mail archive of the barebox mailing list
 help / color / mirror / Atom feed
From: Ahmad Fatoum <a.fatoum@pengutronix.de>
To: barebox@lists.infradead.org
Cc: Ahmad Fatoum <a.fatoum@pengutronix.de>
Subject: [PATCH v3 4/4] usbgadget: add support for USB mass storage gadget
Date: Mon,  3 May 2021 14:45:08 +0200	[thread overview]
Message-ID: <20210503124508.856-5-a.fatoum@pengutronix.de> (raw)
In-Reply-To: <20210503124508.856-1-a.fatoum@pengutronix.de>

This driver is based on the f_mass_storage drivers in Linux v5.11 and
U-Boot v2021.01.

Unlike the U-Boot version, it runs asynchronously without blocking the
bootloader from doing other tasks, like exporting other USB gadgets at
the same time or enabling shell access.

With pollers, enabling this would need a large rework of the code
to be completely callback based, whenever the original Linux code
sleeps waiting for events. With the new bthread support, we can
actually sleep and handover control to other bthreads until there
is actual work to do.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 Documentation/user/usb.rst          |    5 +
 commands/usbgadget.c                |   10 +-
 common/usbgadget.c                  |   10 +-
 drivers/usb/gadget/Kconfig          |   15 +-
 drivers/usb/gadget/Makefile         |    1 +
 drivers/usb/gadget/f_mass_storage.c | 2755 +++++++++++++++++++++++++++
 drivers/usb/gadget/multi.c          |   36 +
 drivers/usb/gadget/storage_common.c |  173 ++
 drivers/usb/gadget/storage_common.h |  245 +++
 include/scsi.h                      |   12 +
 include/usb/gadget-multi.h          |    4 +
 include/usb/mass_storage.h          |   28 +
 include/usb/storage.h               |   87 +
 13 files changed, 3377 insertions(+), 4 deletions(-)
 create mode 100644 drivers/usb/gadget/f_mass_storage.c
 create mode 100644 drivers/usb/gadget/storage_common.c
 create mode 100644 drivers/usb/gadget/storage_common.h
 create mode 100644 include/usb/mass_storage.h
 create mode 100644 include/usb/storage.h

diff --git a/Documentation/user/usb.rst b/Documentation/user/usb.rst
index ca5f8138deda..62f6796c9531 100644
--- a/Documentation/user/usb.rst
+++ b/Documentation/user/usb.rst
@@ -264,6 +264,11 @@ USB Gadget autostart Options
 ``global.usbgadget.acm``
   Boolean flag. If set to 1, CDC ACM function will be created.
   See :ref:`command_usbgadget` -a. (Default 0).
+``global.system.partitions``
+  Common function description for all of DFU, fastboot and USB mass storage
+  gadgets. Both Fastboot and DFU partitions also have dedicated override
+  variables for backwards-compatibility::
+
 ``global.usbgadget.dfu_function``
   Function description for DFU. See :ref:`command_usbgadget` -D [desc].
 ``global.fastboot.partitions``
diff --git a/commands/usbgadget.c b/commands/usbgadget.c
index 07094026db71..290f33eff394 100644
--- a/commands/usbgadget.c
+++ b/commands/usbgadget.c
@@ -21,7 +21,7 @@ static int do_usbgadget(int argc, char *argv[])
 	struct usbgadget_funcs funcs = {};
 	int opt;
 
-	while ((opt = getopt(argc, argv, "asdA::D::b")) > 0) {
+	while ((opt = getopt(argc, argv, "asdA::D::S::b")) > 0) {
 		switch (opt) {
 		case 'a':
 		case 's':
@@ -35,6 +35,10 @@ static int do_usbgadget(int argc, char *argv[])
 			funcs.flags |= USBGADGET_FASTBOOT;
 			funcs.fastboot_opts = optarg;
 			break;
+		case 'S':
+			funcs.flags |= USBGADGET_MASS_STORAGE;
+			funcs.ums_opts = optarg;
+			break;
 		case 'b':
 			funcs.flags |= USBGADGET_EXPORT_BBU;
 			break;
@@ -60,13 +64,15 @@ BAREBOX_CMD_HELP_OPT ("-A <desc>", "Create Android Fastboot function. If 'desc'
 BAREBOX_CMD_HELP_OPT ("-b\t", "include registered barebox update handlers (fastboot specific)")
 BAREBOX_CMD_HELP_OPT ("-D <desc>", "Create DFU function. If 'desc' is not provided, "
 				   "try to use 'global.usbgadget.dfu_function' variable.")
+BAREBOX_CMD_HELP_OPT ("-S <desc>", "Create USB Mass Storage function. If 'desc' is not provided,"
+				   "fallback directly to 'global.system.partitions' variable.")
 BAREBOX_CMD_HELP_OPT ("-d\t", "Disable the currently running gadget")
 BAREBOX_CMD_HELP_END
 
 BAREBOX_CMD_START(usbgadget)
 	.cmd		= do_usbgadget,
 	BAREBOX_CMD_DESC("Create USB Gadget multifunction device")
-	BAREBOX_CMD_OPTS("[-adAD]")
+	BAREBOX_CMD_OPTS("[-adADS]")
 	BAREBOX_CMD_GROUP(CMD_GRP_HWMANIP)
 	BAREBOX_CMD_HELP(cmd_usbgadget_help)
 BAREBOX_CMD_END
diff --git a/common/usbgadget.c b/common/usbgadget.c
index 9bbaa4ea1238..34a685234b95 100644
--- a/common/usbgadget.c
+++ b/common/usbgadget.c
@@ -66,6 +66,14 @@ int usbgadget_register(const struct usbgadget_funcs *funcs)
 		}
 	}
 
+	if (flags & USBGADGET_MASS_STORAGE) {
+		opts->ums_opts.files = parse(funcs->ums_opts);
+		if (IS_ENABLED(CONFIG_USB_GADGET_MASS_STORAGE) && file_list_empty(opts->ums_opts.files)) {
+			file_list_free(opts->ums_opts.files);
+			opts->ums_opts.files = system_partitions_get();
+		}
+	}
+
 	if (flags & USBGADGET_FASTBOOT) {
 		opts->fastboot_opts.files = parse(funcs->fastboot_opts);
 		if (IS_ENABLED(CONFIG_FASTBOOT_BASE) && file_list_empty(opts->fastboot_opts.files)) {
@@ -122,7 +130,7 @@ static int usbgadget_autostart_set(struct param_d *param, void *ctx)
 	if (acm)
 		funcs.flags |= USBGADGET_ACM;
 
-	funcs.flags |= USBGADGET_DFU | USBGADGET_FASTBOOT;
+	funcs.flags |= USBGADGET_DFU | USBGADGET_FASTBOOT | USBGADGET_MASS_STORAGE;
 
 	err = usbgadget_register(&funcs);
 	if (!err)
diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index 4ed6cbbee1b9..574a6821ad04 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -36,10 +36,12 @@ config USB_GADGET_AUTOSTART
 	bool
 	default y
 	prompt "Automatically start usbgadget on boot"
+	select SYSTEM_PARTITIONS if USB_GADGET_MASS_STORAGE
 	help
 	  Enabling this option allows to automatically start a dfu or
 	  fastboot gadget during boot. This behaviour is controlled with
-	  the global.usbgadget.dfu_function and global.fastboot.* variables.
+	  the global.usbgadget.dfu_function, global.system.partitions
+	  and global.fastboot.* variables.
 
 comment "USB Gadget drivers"
 
@@ -57,4 +59,15 @@ config USB_GADGET_FASTBOOT
 	select BANNER
 	select FASTBOOT_BASE
 	prompt "Android Fastboot USB Gadget"
+
+config USB_GADGET_MASS_STORAGE
+	bool
+	select BTHREAD
+	prompt "USB Mass Storage Gadget"
+	help
+	  The Mass Storage Gadget acts as a USB Mass Storage disk drive.
+	  As its storage repository it can use a regular file or a block
+	  device. Multiple storages can be specified at once on
+	  instantiation time.
+
 endif
diff --git a/drivers/usb/gadget/Makefile b/drivers/usb/gadget/Makefile
index 27673fcf0ef6..5ba4920c085a 100644
--- a/drivers/usb/gadget/Makefile
+++ b/drivers/usb/gadget/Makefile
@@ -3,6 +3,7 @@ obj-$(CONFIG_USB_GADGET) += composite.o config.o usbstring.o epautoconf.o udc-co
 obj-$(CONFIG_USB_GADGET_SERIAL) += u_serial.o serial.o f_serial.o f_acm.o
 obj-$(CONFIG_USB_GADGET_DFU) += dfu.o
 obj-$(CONFIG_USB_GADGET_FASTBOOT) += f_fastboot.o
+obj-$(CONFIG_USB_GADGET_MASS_STORAGE) += f_mass_storage.o storage_common.o
 obj-$(CONFIG_USB_GADGET_DRIVER_ARC) += fsl_udc.o
 pbl-$(CONFIG_USB_GADGET_DRIVER_ARC_PBL) += fsl_udc_pbl.o
 obj-$(CONFIG_USB_GADGET_DRIVER_AT91) += at91_udc.o
diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c
new file mode 100644
index 000000000000..07897c02262b
--- /dev/null
+++ b/drivers/usb/gadget/f_mass_storage.c
@@ -0,0 +1,2755 @@
+// SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
+/*
+ * f_mass_storage.c -- Mass Storage USB Composite Function
+ *
+ * Copyright (C) 2003-2008 Alan Stern
+ * Copyright (C) 2009 Samsung Electronics
+ *                    Author: Michal Nazarewicz <m.nazarewicz@samsung.com>
+ * All rights reserved.
+ */
+
+/*
+ * The Mass Storage Function acts as a USB Mass Storage device,
+ * appearing to the host as a disk drive or as a CD-ROM drive.  In
+ * addition to providing an example of a genuinely useful composite
+ * function for a USB device, it also illustrates a technique of
+ * double-buffering for increased throughput.
+ *
+ * Function supports multiple logical units (LUNs).  Backing storage
+ * for each LUN is provided by a regular file or a block device.
+ * Access for each LUN can be limited to read-only.  Moreover, the
+ * function can indicate that LUN is removable and/or CD-ROM.  (The
+ * later implies read-only access.)
+ *
+ * MSF is configured by specifying a fsg_config structure.  It has the
+ * following fields:
+ *
+ *	nluns		Number of LUNs function have (anywhere from 1
+ *				to FSG_MAX_LUNS which is 8).
+ *	luns		An array of LUN configuration values.  This
+ *				should be filled for each LUN that
+ *				function will include (ie. for "nluns"
+ *				LUNs).  Each element of the array has
+ *				the following fields:
+ *	->filename	The path to the backing file for the LUN.
+ *				Required if LUN is not marked as
+ *				removable.
+ *	->ro		Flag specifying access to the LUN shall be
+ *				read-only.  This is implied if CD-ROM
+ *				emulation is enabled as well as when
+ *				it was impossible to open "filename"
+ *				in R/W mode.
+ *	->removable	Flag specifying that LUN shall be indicated as
+ *				being removable.
+ *	->cdrom		Flag specifying that LUN shall be reported as
+ *				being a CD-ROM.
+ *
+ *	lun_name_format	A printf-like format for names of the LUN
+ *				devices.  This determines how the
+ *				directory in sysfs will be named.
+ *				Unless you are using several MSFs in
+ *				a single gadget (as opposed to single
+ *				MSF in many configurations) you may
+ *				leave it as NULL (in which case
+ *				"lun%d" will be used).  In the format
+ *				you can use "%d" to index LUNs for
+ *				MSF's with more than one LUN.  (Beware
+ *				that there is only one integer given
+ *				as an argument for the format and
+ *				specifying invalid format may cause
+ *				unspecified behaviour.)
+ *	thread_name	Name of the kernel thread process used by the
+ *				MSF.  You can safely set it to NULL
+ *				(in which case default "file-storage"
+ *				will be used).
+ *
+ *	vendor_name
+ *	product_name
+ *	release		Information used as a reply to INQUIRY
+ *				request.  To use default set to NULL,
+ *				NULL, 0xffff respectively.  The first
+ *				field should be 8 and the second 16
+ *				characters or less.
+ *
+ *	can_stall	Set to permit function to halt bulk endpoints.
+ *				Disabled on some USB devices known not
+ *				to work correctly.  You should set it
+ *				to true.
+ *
+ * If "removable" is not set for a LUN then a backing file must be
+ * specified.  If it is set, then NULL filename means the LUN's medium
+ * is not loaded (an empty string as "filename" in the fsg_config
+ * structure causes error).  The CD-ROM emulation includes a single
+ * data track and no audio tracks; hence there need be only one
+ * backing file per LUN.  Note also that the CD-ROM block length is
+ * set to 512 rather than the more common value 2048.
+ *
+ *
+ * MSF includes support for module parameters.  If gadget using it
+ * decides to use it, the following module parameters will be
+ * available:
+ *
+ *	file=filename[,filename...]
+ *			Names of the files or block devices used for
+ *				backing storage.
+ *	ro=b[,b...]	Default false, boolean for read-only access.
+ *	removable=b[,b...]
+ *			Default true, boolean for removable media.
+ *	cdrom=b[,b...]	Default false, boolean for whether to emulate
+ *				a CD-ROM drive.
+ *	luns=N		Default N = number of filenames, number of
+ *				LUNs to support.
+ *	stall		Default determined according to the type of
+ *				USB device controller (usually true),
+ *				boolean to permit the driver to halt
+ *				bulk endpoints.
+ *
+ * The module parameters may be prefixed with some string.  You need
+ * to consult gadget's documentation or source to verify whether it is
+ * using those module parameters and if it does what are the prefixes
+ * (look for FSG_MODULE_PARAMETERS() macro usage, what's inside it is
+ * the prefix).
+ *
+ *
+ * Requirements are modest; only a bulk-in and a bulk-out endpoint are
+ * needed.  The memory requirement amounts to two 16K buffers, size
+ * configurable by a parameter.  Support is included for both
+ * full-speed and high-speed operation.
+ *
+ * Note that the driver is slightly non-portable in that it assumes a
+ * single memory/DMA buffer will be useable for bulk-in, bulk-out, and
+ * interrupt-in endpoints.  With most device controllers this isn't an
+ * issue, but there may be some with hardware restrictions that prevent
+ * a buffer from being used by more than one endpoint.
+ *
+ *
+ * The pathnames of the backing files and the ro settings are
+ * available in the attribute files "file" and "ro" in the lun<n> (or
+ * to be more precise in a directory which name comes from
+ * "lun_name_format" option!) subdirectory of the gadget's sysfs
+ * directory.  If the "removable" option is set, writing to these
+ * files will simulate ejecting/loading the medium (writing an empty
+ * line means eject) and adjusting a write-enable tab.  Changes to the
+ * ro setting are not allowed when the medium is loaded or if CD-ROM
+ * emulation is being used.
+ *
+ * When a LUN receive an "eject" SCSI request (Start/Stop Unit),
+ * if the LUN is removable, the backing file is released to simulate
+ * ejection.
+ *
+ *
+ * This function is heavily based on "File-backed Storage Gadget" by
+ * Alan Stern which in turn is heavily based on "Gadget Zero" by David
+ * Brownell.  The driver's SCSI command interface was based on the
+ * "Information technology - Small Computer System Interface - 2"
+ * document from X3T9.2 Project 375D, Revision 10L, 7-SEP-93,
+ * available at <http://www.t10.org/ftp/t10/drafts/s2/s2-r10l.pdf>.
+ * The single exception is opcode 0x23 (READ FORMAT CAPACITIES), which
+ * was based on the "Universal Serial Bus Mass Storage Class UFI
+ * Command Specification" document, Revision 1.0, December 14, 1998,
+ * available at
+ * <http://www.usb.org/developers/devclass_docs/usbmass-ufi10.pdf>.
+ */
+
+/*
+ *				Driver Design
+ *
+ * The MSF is fairly straightforward.  There is a main kernel
+ * thread that handles most of the work.  Interrupt routines field
+ * callbacks from the controller driver: bulk- and interrupt-request
+ * completion notifications, endpoint-0 events, and disconnect events.
+ * Completion events are passed to the main thread by wakeup calls.  Many
+ * ep0 requests are handled at interrupt time, but SetInterface,
+ * SetConfiguration, and device reset requests are forwarded to the
+ * thread in the form of "exceptions" using SIGUSR1 signals (since they
+ * should interrupt any ongoing file I/O operations).
+ *
+ * The thread's main routine implements the standard command/data/status
+ * parts of a SCSI interaction.  It and its subroutines are full of tests
+ * for pending signals/exceptions -- all this polling is necessary since
+ * the kernel has no setjmp/longjmp equivalents.  (Maybe this is an
+ * indication that the driver really wants to be running in userspace.)
+ * An important point is that so long as the thread is alive it keeps an
+ * open reference to the backing file.  This will prevent unmounting
+ * the backing file's underlying filesystem and could cause problems
+ * during system shutdown, for example.  To prevent such problems, the
+ * thread catches INT, TERM, and KILL signals and converts them into
+ * an EXIT exception.
+ *
+ * In normal operation the main thread is started during the gadget's
+ * fsg_bind() callback and stopped during fsg_unbind().  But it can
+ * also exit when it receives a signal, and there's no point leaving
+ * the gadget running when the thread is dead.  At of this moment, MSF
+ * provides no way to deregister the gadget when thread dies -- maybe
+ * a callback functions is needed.
+ *
+ * To provide maximum throughput, the driver uses a circular pipeline of
+ * buffer heads (struct fsg_buffhd).  In principle the pipeline can be
+ * arbitrarily long; in practice the benefits don't justify having more
+ * than 2 stages (i.e., double buffering).  But it helps to think of the
+ * pipeline as being a long one.  Each buffer head contains a bulk-in and
+ * a bulk-out request pointer (since the buffer can be used for both
+ * output and input -- directions always are given from the host's
+ * point of view) as well as a pointer to the buffer and various state
+ * variables.
+ *
+ * Use of the pipeline follows a simple protocol.  There is a variable
+ * (fsg->next_buffhd_to_fill) that points to the next buffer head to use.
+ * At any time that buffer head may still be in use from an earlier
+ * request, so each buffer head has a state variable indicating whether
+ * it is EMPTY, FULL, or BUSY.  Typical use involves waiting for the
+ * buffer head to be EMPTY, filling the buffer either by file I/O or by
+ * USB I/O (during which the buffer head is BUSY), and marking the buffer
+ * head FULL when the I/O is complete.  Then the buffer will be emptied
+ * (again possibly by USB I/O, during which it is marked BUSY) and
+ * finally marked EMPTY again (possibly by a completion routine).
+ *
+ * A module parameter tells the driver to avoid stalling the bulk
+ * endpoints wherever the transport specification allows.  This is
+ * necessary for some UDCs like the SuperH, which cannot reliably clear a
+ * halt on a bulk endpoint.  However, under certain circumstances the
+ * Bulk-only specification requires a stall.  In such cases the driver
+ * will halt the endpoint and set a flag indicating that it should clear
+ * the halt in software during the next device reset.  Hopefully this
+ * will permit everything to work correctly.  Furthermore, although the
+ * specification allows the bulk-out endpoint to halt when the host sends
+ * too much data, implementing this would cause an unavoidable race.
+ * The driver will always use the "no-stall" approach for OUT transfers.
+ *
+ * One subtle point concerns sending status-stage responses for ep0
+ * requests.  Some of these requests, such as device reset, can involve
+ * interrupting an ongoing file I/O operation, which might take an
+ * arbitrarily long time.  During that delay the host might give up on
+ * the original ep0 request and issue a new one.  When that happens the
+ * driver should not notify the host about completion of the original
+ * request, as the host will no longer be waiting for it.  So the driver
+ * assigns to each ep0 request a unique tag, and it keeps track of the
+ * tag value of the request associated with a long-running exception
+ * (device-reset, interface-change, or configuration-change).  When the
+ * exception handler is finished, the status-stage response is submitted
+ * only if the current ep0 request tag is equal to the exception request
+ * tag.  Thus only the most recently received ep0 request will get a
+ * status-stage response.
+ *
+ * Warning: This driver source file is too long.  It ought to be split up
+ * into a header file plus about 3 separate .c files, to handle the details
+ * of the Gadget, USB Mass Storage, and SCSI protocols.
+ */
+
+/* #define VERBOSE_DEBUG */
+/* #define DUMP_MSGS */
+
+#define pr_fmt(fmt) "f_ums: " fmt
+
+#include <common.h>
+#include <unistd.h>
+#include <linux/stat.h>
+#include <linux/wait.h>
+#include <fcntl.h>
+#include <file-list.h>
+#include <dma.h>
+#include <linux/bug.h>
+#include <linux/rwsem.h>
+#include <linux/pagemap.h>
+#include <disks.h>
+#include <scsi.h>
+
+#include <linux/err.h>
+#include <usb/mass_storage.h>
+
+#include <asm/unaligned.h>
+#include <linux/bitops.h>
+#include <usb/gadget.h>
+#include <usb/composite.h>
+#include <linux/bitmap.h>
+#include <linux/completion.h>
+#include <bthread.h>
+#include <sched.h>
+
+
+/*------------------------------------------------------------------------*/
+
+#define FSG_DRIVER_DESC	"ums"
+#define UMS_NAME_LEN 16
+
+#define FSG_DRIVER_VERSION	"2012/06/5"
+
+static const char fsg_string_interface[] = "Mass Storage";
+
+#include "storage_common.h"
+
+/* Static strings, in UTF-8 (for simplicity we use only ASCII characters) */
+struct usb_string		fsg_strings[] = {
+	{FSG_STRING_INTERFACE,		fsg_string_interface},
+	{}
+};
+
+static struct usb_gadget_strings	fsg_stringtab = {
+	.language	= 0x0409,		/* en-us */
+	.strings	= fsg_strings,
+};
+
+/*-------------------------------------------------------------------------*/
+
+struct bthread *thread_task;
+
+struct kref {int x; };
+
+struct fsg_dev;
+
+static struct file_list *ums_files;
+
+/* Data shared by all the FSG instances. */
+struct fsg_common {
+	struct usb_gadget	*gadget;
+	struct fsg_dev		*fsg, *new_fsg;
+
+	struct usb_ep		*ep0;		/* Copy of gadget->ep0 */
+	struct usb_request	*ep0req;	/* Copy of cdev->req */
+	unsigned int		ep0_req_tag;
+
+	struct fsg_buffhd	*next_buffhd_to_fill;
+	struct fsg_buffhd	*next_buffhd_to_drain;
+	struct fsg_buffhd	buffhds[FSG_NUM_BUFFERS];
+
+	int			cmnd_size;
+	u8			cmnd[MAX_COMMAND_SIZE];
+
+	unsigned int		nluns;
+	unsigned int		lun;
+	struct fsg_lun          luns[FSG_MAX_LUNS];
+
+	unsigned int		bulk_out_maxpacket;
+	enum fsg_state		state;		/* For exception handling */
+	unsigned int		exception_req_tag;
+
+	enum data_direction	data_dir;
+	u32			data_size;
+	u32			data_size_from_cmnd;
+	u32			tag;
+	u32			residue;
+	u32			usb_amount_left;
+
+	unsigned int		can_stall:1;
+	unsigned int		phase_error:1;
+	unsigned int		short_packet_received:1;
+	unsigned int		bad_lun_okay:1;
+	unsigned int		running:1;
+
+	struct completion	thread_wakeup_needed;
+
+	/* Callback functions. */
+	const struct fsg_operations	*ops;
+	/* Gadget's private data. */
+	void			*private_data;
+
+	const char *vendor_name;		/*  8 characters or less */
+	const char *product_name;		/* 16 characters or less */
+	u16 release;
+
+	/* Vendor (8 chars), product (16 chars), release (4
+	 * hexadecimal digits) and NUL byte */
+	char inquiry_string[8 + 16 + 4 + 1];
+};
+
+struct fsg_config {
+	unsigned nluns;
+	struct fsg_lun_config {
+		const char *filename;
+		char ro;
+		char removable;
+		char cdrom;
+		char nofua;
+	} luns[FSG_MAX_LUNS];
+
+	/* Callback functions. */
+	const struct fsg_operations     *ops;
+	/* Gadget's private data. */
+	void			*private_data;
+
+	const char *vendor_name;		/*  8 characters or less */
+	const char *product_name;		/* 16 characters or less */
+
+	char			can_stall;
+};
+
+struct fsg_dev {
+	struct usb_function	function;
+	struct usb_gadget	*gadget;	/* Copy of cdev->gadget */
+	struct fsg_common	*common;
+
+	u16			interface_number;
+
+	unsigned int		bulk_in_enabled:1;
+	unsigned int		bulk_out_enabled:1;
+
+	unsigned long		atomic_bitflags;
+#define IGNORE_BULK_OUT		0
+
+	struct usb_ep		*bulk_in;
+	struct usb_ep		*bulk_out;
+};
+
+
+static inline int __fsg_is_set(struct fsg_common *common,
+			       const char *func, unsigned line)
+{
+	if (common->fsg)
+		return 1;
+	ERROR(common, "common->fsg is NULL in %s at %u\n", func, line);
+	WARN_ON(1);
+
+	return 0;
+}
+
+#define fsg_is_set(common) likely(__fsg_is_set(common, __func__, __LINE__))
+
+
+static inline struct fsg_dev *fsg_from_func(struct usb_function *f)
+{
+	return container_of(f, struct fsg_dev, function);
+}
+
+static inline struct f_ums_opts *
+fsg_opts_from_func_inst(const struct usb_function_instance *fi)
+{
+	return container_of(fi, struct f_ums_opts, func_inst);
+}
+
+typedef void (*fsg_routine_t)(struct fsg_dev *);
+
+static int exception_in_progress(struct fsg_common *common)
+{
+	return common->state > FSG_STATE_IDLE;
+}
+
+/* Make bulk-out requests be divisible by the maxpacket size */
+static void set_bulk_out_req_length(struct fsg_common *common,
+		struct fsg_buffhd *bh, unsigned int length)
+{
+	unsigned int	rem;
+
+	bh->bulk_out_intended_length = length;
+	rem = length % common->bulk_out_maxpacket;
+	if (rem > 0)
+		length += common->bulk_out_maxpacket - rem;
+	bh->outreq->length = length;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static struct f_ums_opts ums[14]; // FIXME
+static int ums_count;
+
+static int fsg_set_halt(struct fsg_dev *fsg, struct usb_ep *ep)
+{
+	const char	*name;
+
+	if (ep == fsg->bulk_in)
+		name = "bulk-in";
+	else if (ep == fsg->bulk_out)
+		name = "bulk-out";
+	else
+		name = ep->name;
+	DBG(fsg, "%s set halt\n", name);
+	return usb_ep_set_halt(ep);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* These routines may be called in process context or in_irq */
+
+/* Caller must hold fsg->lock */
+static void wakeup_thread(struct fsg_common *common)
+{
+	complete(&common->thread_wakeup_needed);
+}
+
+static void report_exception(const char *prefix, enum fsg_state state)
+{
+	const char *msg = "<unknown>";
+	switch (state) {
+	/* This one isn't used anywhere */
+	case FSG_STATE_COMMAND_PHASE:
+		msg = "Command Phase";
+		break;
+	case FSG_STATE_DATA_PHASE:
+		msg = "Data Phase";
+		break;
+	case FSG_STATE_STATUS_PHASE:
+		msg = "Status Phase";
+		break;
+
+	case FSG_STATE_IDLE:
+		msg = "Idle";
+		break;
+	case FSG_STATE_ABORT_BULK_OUT:
+		msg = "abort bulk out";
+		break;
+	case FSG_STATE_RESET:
+		msg = "reset";
+		break;
+	case FSG_STATE_INTERFACE_CHANGE:
+		msg = "interface change";
+		break;
+	case FSG_STATE_CONFIG_CHANGE:
+		msg = "config change";
+		break;
+	case FSG_STATE_DISCONNECT:
+		msg = "disconnect";
+		break;
+	case FSG_STATE_EXIT:
+		msg = "exit";
+		break;
+	case FSG_STATE_TERMINATED:
+		msg = "terminated";
+		break;
+	}
+
+	pr_debug("%s: %s\n", prefix, msg);
+}
+
+static void raise_exception(struct fsg_common *common, enum fsg_state new_state)
+{
+	/* Do nothing if a higher-priority exception is already in progress.
+	 * If a lower-or-equal priority exception is in progress, preempt it
+	 * and notify the main thread by sending it a signal. */
+	if (common->state <= new_state) {
+		report_exception("raising", new_state);
+		common->exception_req_tag = common->ep0_req_tag;
+		common->state = new_state;
+		wakeup_thread(common);
+	}
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int ep0_queue(struct fsg_common *common)
+{
+	int	rc;
+
+	rc = usb_ep_queue(common->ep0, common->ep0req);
+	common->ep0->driver_data = common;
+	if (rc != 0 && rc != -ESHUTDOWN) {
+		/* We can't do much more than wait for a reset */
+		WARNING(common, "error in submission: %s --> %d\n",
+			common->ep0->name, rc);
+	}
+	return rc;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* Bulk and interrupt endpoint completion handlers.
+ * These always run in_irq. */
+
+static void bulk_in_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct fsg_common	*common = ep->driver_data;
+	struct fsg_buffhd	*bh = req->context;
+
+	if (req->status || req->actual != req->length)
+		DBG(common, "%s --> %d, %u/%u\n", __func__,
+				req->status, req->actual, req->length);
+	if (req->status == -ECONNRESET)		/* Request was cancelled */
+		usb_ep_fifo_flush(ep);
+
+	/* Hold the lock while we update the request and buffer states */
+	bh->inreq_busy = 0;
+	bh->state = BUF_STATE_EMPTY;
+	wakeup_thread(common);
+}
+
+static void bulk_out_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct fsg_common	*common = ep->driver_data;
+	struct fsg_buffhd	*bh = req->context;
+
+	dump_msg(common, "bulk-out", req->buf, req->actual);
+	if (req->status || req->actual != bh->bulk_out_intended_length)
+		DBG(common, "%s --> %d, %u/%u\n", __func__,
+				req->status, req->actual,
+				bh->bulk_out_intended_length);
+	if (req->status == -ECONNRESET)		/* Request was cancelled */
+		usb_ep_fifo_flush(ep);
+
+	/* Hold the lock while we update the request and buffer states */
+	bh->outreq_busy = 0;
+	bh->state = BUF_STATE_FULL;
+	wakeup_thread(common);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* Ep0 class-specific handlers.  These always run in_irq. */
+
+static int fsg_setup(struct usb_function *f,
+		const struct usb_ctrlrequest *ctrl)
+{
+	struct fsg_dev		*fsg = fsg_from_func(f);
+	struct usb_request	*req = fsg->common->ep0req;
+	u16			w_index = get_unaligned_le16(&ctrl->wIndex);
+	u16			w_value = get_unaligned_le16(&ctrl->wValue);
+	u16			w_length = get_unaligned_le16(&ctrl->wLength);
+
+	if (!fsg_is_set(fsg->common))
+		return -EOPNOTSUPP;
+
+	switch (ctrl->bRequest) {
+
+	case US_BULK_RESET_REQUEST:
+		if (ctrl->bRequestType !=
+		    (USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE))
+			break;
+		if (w_index != fsg->interface_number || w_value != 0)
+			return -EDOM;
+
+		/* Raise an exception to stop the current operation
+		 * and reinitialize our state. */
+		DBG(fsg, "bulk reset request\n");
+		raise_exception(fsg->common, FSG_STATE_RESET);
+		return DELAYED_STATUS;
+
+	case US_BULK_GET_MAX_LUN:
+		if (ctrl->bRequestType !=
+		    (USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE))
+			break;
+		if (w_index != fsg->interface_number || w_value != 0)
+			return -EDOM;
+		VDBG(fsg, "get max LUN\n");
+		*(u8 *) req->buf = fsg->common->nluns - 1;
+
+		/* Respond with data/status */
+		req->length = min((u16)1, w_length);
+		return ep0_queue(fsg->common);
+	}
+
+	VDBG(fsg,
+	     "unknown class-specific control req "
+	     "%02x.%02x v%04x i%04x l%u\n",
+	     ctrl->bRequestType, ctrl->bRequest,
+	     get_unaligned_le16(&ctrl->wValue), w_index, w_length);
+	return -EOPNOTSUPP;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* All the following routines run in process context */
+
+/* Use this for bulk or interrupt transfers, not ep0 */
+static void start_transfer(struct fsg_dev *fsg, struct usb_ep *ep,
+		struct usb_request *req, int *pbusy,
+		enum fsg_buffer_state *state)
+{
+	int	rc;
+
+	if (ep == fsg->bulk_in)
+		dump_msg(fsg, "bulk-in", req->buf, req->length);
+
+	*pbusy = 1;
+	*state = BUF_STATE_BUSY;
+	rc = usb_ep_queue(ep, req);
+	if (rc != 0) {
+		*pbusy = 0;
+		*state = BUF_STATE_EMPTY;
+
+		/* We can't do much more than wait for a reset */
+
+		/* Note: currently the net2280 driver fails zero-length
+		 * submissions if DMA is enabled. */
+		if (rc != -ESHUTDOWN && !(rc == -EOPNOTSUPP &&
+						req->length == 0))
+			WARNING(fsg, "error in submission: %s --> %d\n",
+					ep->name, rc);
+	}
+}
+
+#define START_TRANSFER_OR(common, ep_name, req, pbusy, state)		\
+	if (fsg_is_set(common))						\
+		start_transfer((common)->fsg, (common)->fsg->ep_name,	\
+			       req, pbusy, state);			\
+	else
+
+#define START_TRANSFER(common, ep_name, req, pbusy, state)		\
+	START_TRANSFER_OR(common, ep_name, req, pbusy, state) (void)0
+
+static int sleep_thread(struct fsg_common *common)
+{
+	int ret;
+
+	/* Wait until a signal arrives or we are woken up */
+	ret = wait_for_completion_interruptible(&common->thread_wakeup_needed);
+	if (ret)
+		return ret;
+
+	reinit_completion(&common->thread_wakeup_needed);
+	return 0;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int do_read(struct fsg_common *common)
+{
+	struct fsg_lun		*curlun = &common->luns[common->lun];
+	u32			lba;
+	struct fsg_buffhd	*bh;
+	int			rc;
+	u32			amount_left;
+	loff_t			file_offset;
+	unsigned int		amount;
+	unsigned int		partial_page;
+	ssize_t			nread;
+
+	/* Get the starting Logical Block Address and check that it's
+	 * not too big */
+	if (common->cmnd[0] == SCSI_READ6)
+		lba = get_unaligned_be24(&common->cmnd[1]);
+	else {
+		lba = get_unaligned_be32(&common->cmnd[2]);
+
+		/* We allow DPO (Disable Page Out = don't save data in the
+		 * cache) and FUA (Force Unit Access = don't read from the
+		 * cache), but we don't implement them. */
+		if ((common->cmnd[1] & ~0x18) != 0) {
+			curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
+			return -EINVAL;
+		}
+	}
+	if (lba >= curlun->num_sectors) {
+		curlun->sense_data = SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
+		return -EINVAL;
+	}
+	file_offset = ((loff_t) lba) << 9;
+
+	/* Carry out the file reads */
+	amount_left = common->data_size_from_cmnd;
+	if (unlikely(amount_left == 0))
+		return -EIO;		/* No default reply */
+
+	for (;;) {
+		/* Wait for the next buffer to become available */
+		bh = common->next_buffhd_to_fill;
+		while (bh->state != BUF_STATE_EMPTY) {
+			rc = sleep_thread(common);
+			if (rc)
+				return rc;
+		}
+
+		/* Figure out how much we need to read:
+		 * Try to read the remaining amount.
+		 * But don't read more than the buffer size.
+		 * And don't try to read past the end of the file.
+		 * Finally, if we're not at a page boundary, don't read past
+		 *	the next page.
+		 * If this means reading 0 then we were asked to read past
+		 *	the end of file. */
+		amount = min(amount_left, FSG_BUFLEN);
+		partial_page = file_offset & (PAGE_CACHE_SIZE - 1);
+		if (partial_page > 0)
+			amount = min(amount, (unsigned int) PAGE_CACHE_SIZE -
+					partial_page);
+
+
+		/* If we were asked to read past the end of file,
+		 * end with an empty buffer. */
+		if (amount == 0) {
+			curlun->sense_data =
+					SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
+			curlun->info_valid = 1;
+			bh->inreq->length = 0;
+			bh->state = BUF_STATE_FULL;
+			break;
+		}
+
+		/* Perform the read */
+		nread = pread(ums[common->lun].fd, bh->buf, amount, file_offset);
+
+		VLDBG(curlun, "file read %u @ %llu -> %zd\n", amount,
+				(unsigned long long) file_offset,
+				nread);
+		if (nread <= 0) {
+			const char *err = nread ? strerror(-nread) : "EOF";
+			LDBG(curlun, "error in file read: %s\n", err);
+			nread = 0;
+		} else if (nread < amount) {
+			LDBG(curlun, "partial file read: %d/%u\n",
+					(int) nread, amount);
+			nread -= (nread & 511);	/* Round down to a block */
+		}
+		file_offset  += nread;
+		amount_left  -= nread;
+		common->residue -= nread;
+		bh->inreq->length = nread;
+		bh->state = BUF_STATE_FULL;
+
+		/* If an error occurred, report it and its position */
+		if (nread < amount) {
+			curlun->sense_data = SS_UNRECOVERED_READ_ERROR;
+			curlun->info_valid = 1;
+			break;
+		}
+
+		if (amount_left == 0)
+			break;		/* No more left to read */
+
+		/* Send this buffer and go read some more */
+		bh->inreq->zero = 0;
+		START_TRANSFER_OR(common, bulk_in, bh->inreq,
+			       &bh->inreq_busy, &bh->state)
+			/* Don't know what to do if
+			 * common->fsg is NULL */
+			return -EIO;
+		common->next_buffhd_to_fill = bh->next;
+	}
+
+	return -EIO;		/* No default reply */
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int do_write(struct fsg_common *common)
+{
+	struct fsg_lun		*curlun = &common->luns[common->lun];
+	u32			lba;
+	struct fsg_buffhd	*bh;
+	int			get_some_more;
+	u32			amount_left_to_req, amount_left_to_write;
+	loff_t			usb_offset, file_offset;
+	unsigned int		amount;
+	unsigned int		partial_page;
+	ssize_t			nwritten;
+	int			rc;
+
+	if (curlun->ro) {
+		curlun->sense_data = SS_WRITE_PROTECTED;
+		return -EINVAL;
+	}
+
+	/* Get the starting Logical Block Address and check that it's
+	 * not too big */
+	if (common->cmnd[0] == SCSI_WRITE6)
+		lba = get_unaligned_be24(&common->cmnd[1]);
+	else {
+		lba = get_unaligned_be32(&common->cmnd[2]);
+
+		/* We allow DPO (Disable Page Out = don't save data in the
+		 * cache) and FUA (Force Unit Access = write directly to the
+		 * medium).  We don't implement DPO; we implement FUA by
+		 * performing synchronous output. */
+		if (common->cmnd[1] & ~0x18) {
+			curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
+			return -EINVAL;
+		}
+	}
+	if (lba >= curlun->num_sectors) {
+		curlun->sense_data = SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
+		return -EINVAL;
+	}
+
+	/* Carry out the file writes */
+	get_some_more = 1;
+	file_offset = usb_offset = ((loff_t) lba) << 9;
+	amount_left_to_req = common->data_size_from_cmnd;
+	amount_left_to_write = common->data_size_from_cmnd;
+
+	while (amount_left_to_write > 0) {
+
+		/* Queue a request for more data from the host */
+		bh = common->next_buffhd_to_fill;
+		if (bh->state == BUF_STATE_EMPTY && get_some_more) {
+
+			/* Figure out how much we want to get:
+			 * Try to get the remaining amount.
+			 * But don't get more than the buffer size.
+			 * And don't try to go past the end of the file.
+			 * If we're not at a page boundary,
+			 *	don't go past the next page.
+			 * If this means getting 0, then we were asked
+			 *	to write past the end of file.
+			 * Finally, round down to a block boundary. */
+			amount = min(amount_left_to_req, FSG_BUFLEN);
+			partial_page = usb_offset & (PAGE_CACHE_SIZE - 1);
+			if (partial_page > 0)
+				amount = min(amount,
+	(unsigned int) PAGE_CACHE_SIZE - partial_page);
+
+			if (amount == 0) {
+				get_some_more = 0;
+				curlun->sense_data =
+					SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
+				curlun->info_valid = 1;
+				continue;
+			}
+			amount -= (amount & 511);
+			if (amount == 0) {
+
+				/* Why were we were asked to transfer a
+				 * partial block? */
+				get_some_more = 0;
+				continue;
+			}
+
+			/* Get the next buffer */
+			usb_offset += amount;
+			common->usb_amount_left -= amount;
+			amount_left_to_req -= amount;
+			if (amount_left_to_req == 0)
+				get_some_more = 0;
+
+			/* amount is always divisible by 512, hence by
+			 * the bulk-out maxpacket size */
+			bh->outreq->length = amount;
+			bh->bulk_out_intended_length = amount;
+			bh->outreq->short_not_ok = 1;
+			START_TRANSFER_OR(common, bulk_out, bh->outreq,
+					  &bh->outreq_busy, &bh->state)
+				/* Don't know what to do if
+				 * common->fsg is NULL */
+				return -EIO;
+			common->next_buffhd_to_fill = bh->next;
+			continue;
+		}
+
+		/* Write the received data to the backing file */
+		bh = common->next_buffhd_to_drain;
+		if (bh->state == BUF_STATE_EMPTY && !get_some_more)
+			break;			/* We stopped early */
+		if (bh->state == BUF_STATE_FULL) {
+			common->next_buffhd_to_drain = bh->next;
+			bh->state = BUF_STATE_EMPTY;
+
+			/* Did something go wrong with the transfer? */
+			if (bh->outreq->status != 0) {
+				curlun->sense_data = SS_COMMUNICATION_FAILURE;
+				curlun->info_valid = 1;
+				break;
+			}
+
+			amount = bh->outreq->actual;
+
+			/* Perform the write */
+			nwritten = pwrite(ums[common->lun].fd, bh->buf, amount, file_offset);
+
+			VLDBG(curlun, "file write %u @ %llu -> %zd\n", amount,
+					(unsigned long long) file_offset,
+					nwritten);
+
+			if (nwritten < 0) {
+				LDBG(curlun, "error in file write: %pe\n", ERR_PTR(nwritten));
+				nwritten = 0;
+			} else if (nwritten < amount) {
+				LDBG(curlun, "partial file write: %d/%u\n",
+						(int) nwritten, amount);
+				nwritten -= (nwritten & 511);
+				/* Round down to a block */
+			}
+			file_offset += nwritten;
+			amount_left_to_write -= nwritten;
+			common->residue -= nwritten;
+
+			/* If an error occurred, report it and its position */
+			if (nwritten < amount) {
+				pr_warn("nwritten:%zd amount:%u\n", nwritten,
+				       amount);
+				curlun->sense_data = SS_WRITE_ERROR;
+				curlun->info_valid = 1;
+				break;
+			}
+
+			/* Did the host decide to stop early? */
+			if (bh->outreq->actual != bh->outreq->length) {
+				common->short_packet_received = 1;
+				break;
+			}
+			continue;
+		}
+
+		/* Wait for something to happen */
+		rc = sleep_thread(common);
+		if (rc)
+			return rc;
+	}
+
+	return -EIO;		/* No default reply */
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int do_synchronize_cache(struct fsg_common *common)
+{
+	return 0;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int do_verify(struct fsg_common *common)
+{
+	struct fsg_lun		*curlun = &common->luns[common->lun];
+	u32			lba;
+	u32			verification_length;
+	struct fsg_buffhd	*bh = common->next_buffhd_to_fill;
+	loff_t			file_offset;
+	u32			amount_left;
+	unsigned int		amount;
+	ssize_t			nread;
+
+	/* Get the starting Logical Block Address and check that it's
+	 * not too big */
+	lba = get_unaligned_be32(&common->cmnd[2]);
+	if (lba >= curlun->num_sectors) {
+		curlun->sense_data = SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
+		return -EINVAL;
+	}
+
+	/* We allow DPO (Disable Page Out = don't save data in the
+	 * cache) but we don't implement it. */
+	if (common->cmnd[1] & ~0x10) {
+		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
+		return -EINVAL;
+	}
+
+	verification_length = get_unaligned_be16(&common->cmnd[7]);
+	if (unlikely(verification_length == 0))
+		return -EIO;		/* No default reply */
+
+	/* Prepare to carry out the file verify */
+	amount_left = verification_length << 9;
+	file_offset = ((loff_t) lba) << 9;
+
+	/* Write out all the dirty buffers before invalidating them */
+
+	/* Just try to read the requested blocks */
+	while (amount_left > 0) {
+
+		/* Figure out how much we need to read:
+		 * Try to read the remaining amount, but not more than
+		 * the buffer size.
+		 * And don't try to read past the end of the file.
+		 * If this means reading 0 then we were asked to read
+		 * past the end of file. */
+		amount = min(amount_left, FSG_BUFLEN);
+		if (amount == 0) {
+			curlun->sense_data =
+					SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
+			curlun->info_valid = 1;
+			break;
+		}
+
+		/* Perform the read */
+		nread = pread(ums[common->lun].fd, bh->buf, amount, file_offset);
+
+		VLDBG(curlun, "file read %u @ %llu -> %zd\n", amount,
+				(unsigned long long) file_offset,
+				nread);
+		if (nread <= 0) {
+			const char *err = nread ? strerror(-nread) : "EOF";
+			LDBG(curlun, "error in file read: %s\n", err);
+			nread = 0;
+		} else if (nread < amount) {
+			LDBG(curlun, "partial file verify: %d/%u\n",
+					(int) nread, amount);
+			nread -= (nread & 511);	/* Round down to a sector */
+		}
+		if (nread == 0) {
+			curlun->sense_data = SS_UNRECOVERED_READ_ERROR;
+			curlun->info_valid = 1;
+			break;
+		}
+		file_offset += nread;
+		amount_left -= nread;
+	}
+	return 0;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int do_inquiry(struct fsg_common *common, struct fsg_buffhd *bh)
+{
+	struct fsg_lun *curlun = &common->luns[common->lun];
+	static const char vendor_id[] = "Linux   ";
+	u8	*buf = (u8 *) bh->buf;
+
+	if (!curlun) {		/* Unsupported LUNs are okay */
+		common->bad_lun_okay = 1;
+		memset(buf, 0, 36);
+		buf[0] = 0x7f;		/* Unsupported, no device-type */
+		buf[4] = 31;		/* Additional length */
+		return 36;
+	}
+
+	memset(buf, 0, 8);
+	buf[0] = TYPE_DISK;
+	buf[1] = curlun->removable ? 0x80 : 0;
+	buf[2] = 2;		/* ANSI SCSI level 2 */
+	buf[3] = 2;		/* SCSI-2 INQUIRY data format */
+	buf[4] = 31;		/* Additional length */
+				/* No special options */
+	sprintf((char *) (buf + 8), "%-8s%-16s%04x", (char*) vendor_id ,
+			ums[common->lun].name, (u16) 0xffff);
+
+	return 36;
+}
+
+
+static int do_request_sense(struct fsg_common *common, struct fsg_buffhd *bh)
+{
+	struct fsg_lun	*curlun = &common->luns[common->lun];
+	u8		*buf = (u8 *) bh->buf;
+	u32		sd, sdinfo = 0;
+	int		valid;
+
+	/*
+	 * From the SCSI-2 spec., section 7.9 (Unit attention condition):
+	 *
+	 * If a REQUEST SENSE command is received from an initiator
+	 * with a pending unit attention condition (before the target
+	 * generates the contingent allegiance condition), then the
+	 * target shall either:
+	 *   a) report any pending sense data and preserve the unit
+	 *	attention condition on the logical unit, or,
+	 *   b) report the unit attention condition, may discard any
+	 *	pending sense data, and clear the unit attention
+	 *	condition on the logical unit for that initiator.
+	 *
+	 * FSG normally uses option a); enable this code to use option b).
+	 */
+#if 0
+	if (curlun && curlun->unit_attention_data != SS_NO_SENSE) {
+		curlun->sense_data = curlun->unit_attention_data;
+		curlun->unit_attention_data = SS_NO_SENSE;
+	}
+#endif
+
+	if (!curlun) {		/* Unsupported LUNs are okay */
+		common->bad_lun_okay = 1;
+		sd = SS_LOGICAL_UNIT_NOT_SUPPORTED;
+		valid = 0;
+	} else {
+		sd = curlun->sense_data;
+		valid = curlun->info_valid << 7;
+		curlun->sense_data = SS_NO_SENSE;
+		curlun->info_valid = 0;
+	}
+
+	memset(buf, 0, 18);
+	buf[0] = valid | 0x70;			/* Valid, current error */
+	buf[2] = SK(sd);
+	put_unaligned_be32(sdinfo, &buf[3]);	/* Sense information */
+	buf[7] = 18 - 8;			/* Additional sense length */
+	buf[12] = ASC(sd);
+	buf[13] = ASCQ(sd);
+	return 18;
+}
+
+static int do_read_capacity(struct fsg_common *common, struct fsg_buffhd *bh)
+{
+	struct fsg_lun	*curlun = &common->luns[common->lun];
+	u32		lba = get_unaligned_be32(&common->cmnd[2]);
+	int		pmi = common->cmnd[8];
+	u8		*buf = (u8 *) bh->buf;
+
+	/* Check the PMI and LBA fields */
+	if (pmi > 1 || (pmi == 0 && lba != 0)) {
+		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
+		return -EINVAL;
+	}
+
+	put_unaligned_be32(curlun->num_sectors - 1, &buf[0]);
+						/* Max logical block */
+	put_unaligned_be32(512, &buf[4]);	/* Block length */
+	return 8;
+}
+
+static int do_read_header(struct fsg_common *common, struct fsg_buffhd *bh)
+{
+	struct fsg_lun	*curlun = &common->luns[common->lun];
+	int		msf = common->cmnd[1] & 0x02;
+	u32		lba = get_unaligned_be32(&common->cmnd[2]);
+	u8		*buf = (u8 *) bh->buf;
+
+	if (common->cmnd[1] & ~0x02) {		/* Mask away MSF */
+		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
+		return -EINVAL;
+	}
+	if (lba >= curlun->num_sectors) {
+		curlun->sense_data = SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
+		return -EINVAL;
+	}
+
+	memset(buf, 0, 8);
+	buf[0] = 0x01;		/* 2048 bytes of user data, rest is EC */
+	store_cdrom_address(&buf[4], msf, lba);
+	return 8;
+}
+
+
+static int do_read_toc(struct fsg_common *common, struct fsg_buffhd *bh)
+{
+	struct fsg_lun	*curlun = &common->luns[common->lun];
+	int		msf = common->cmnd[1] & 0x02;
+	int		start_track = common->cmnd[6];
+	u8		*buf = (u8 *) bh->buf;
+
+	if ((common->cmnd[1] & ~0x02) != 0 ||	/* Mask away MSF */
+			start_track > 1) {
+		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
+		return -EINVAL;
+	}
+
+	memset(buf, 0, 20);
+	buf[1] = (20-2);		/* TOC data length */
+	buf[2] = 1;			/* First track number */
+	buf[3] = 1;			/* Last track number */
+	buf[5] = 0x16;			/* Data track, copying allowed */
+	buf[6] = 0x01;			/* Only track is number 1 */
+	store_cdrom_address(&buf[8], msf, 0);
+
+	buf[13] = 0x16;			/* Lead-out track is data */
+	buf[14] = 0xAA;			/* Lead-out track number */
+	store_cdrom_address(&buf[16], msf, curlun->num_sectors);
+
+	return 20;
+}
+
+static int do_mode_sense(struct fsg_common *common, struct fsg_buffhd *bh)
+{
+	struct fsg_lun	*curlun = &common->luns[common->lun];
+	int		mscmnd = common->cmnd[0];
+	u8		*buf = (u8 *) bh->buf;
+	u8		*buf0 = buf;
+	int		pc, page_code;
+	int		changeable_values, all_pages;
+	int		valid_page = 0;
+	int		len, limit;
+
+	if ((common->cmnd[1] & ~0x08) != 0) {	/* Mask away DBD */
+		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
+		return -EINVAL;
+	}
+	pc = common->cmnd[2] >> 6;
+	page_code = common->cmnd[2] & 0x3f;
+	if (pc == 3) {
+		curlun->sense_data = SS_SAVING_PARAMETERS_NOT_SUPPORTED;
+		return -EINVAL;
+	}
+	changeable_values = (pc == 1);
+	all_pages = (page_code == 0x3f);
+
+	/* Write the mode parameter header.  Fixed values are: default
+	 * medium type, no cache control (DPOFUA), and no block descriptors.
+	 * The only variable value is the WriteProtect bit.  We will fill in
+	 * the mode data length later. */
+	memset(buf, 0, 8);
+	if (mscmnd == SCSI_MODE_SEN6) {
+		buf[2] = (curlun->ro ? 0x80 : 0x00);		/* WP, DPOFUA */
+		buf += 4;
+		limit = 255;
+	} else {			/* SCSI_MODE_SEN10 */
+		buf[3] = (curlun->ro ? 0x80 : 0x00);		/* WP, DPOFUA */
+		buf += 8;
+		limit = 65535;		/* Should really be FSG_BUFLEN */
+	}
+
+	/* No block descriptors */
+
+	/* The mode pages, in numerical order.  The only page we support
+	 * is the Caching page. */
+	if (page_code == 0x08 || all_pages) {
+		valid_page = 1;
+		buf[0] = 0x08;		/* Page code */
+		buf[1] = 10;		/* Page length */
+		memset(buf+2, 0, 10);	/* None of the fields are changeable */
+
+		if (!changeable_values) {
+			buf[2] = 0x04;	/* Write cache enable, */
+					/* Read cache not disabled */
+					/* No cache retention priorities */
+			put_unaligned_be16(0xffff, &buf[4]);
+					/* Don't disable prefetch */
+					/* Minimum prefetch = 0 */
+			put_unaligned_be16(0xffff, &buf[8]);
+					/* Maximum prefetch */
+			put_unaligned_be16(0xffff, &buf[10]);
+					/* Maximum prefetch ceiling */
+		}
+		buf += 12;
+	}
+
+	/* Check that a valid page was requested and the mode data length
+	 * isn't too long. */
+	len = buf - buf0;
+	if (!valid_page || len > limit) {
+		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
+		return -EINVAL;
+	}
+
+	/*  Store the mode data length */
+	if (mscmnd == SCSI_MODE_SEN6)
+		buf0[0] = len - 1;
+	else
+		put_unaligned_be16(len - 2, buf0);
+	return len;
+}
+
+
+static int do_start_stop(struct fsg_common *common)
+{
+	struct fsg_lun	*curlun = &common->luns[common->lun];
+
+	if (!curlun) {
+		return -EINVAL;
+	} else if (!curlun->removable) {
+		curlun->sense_data = SS_INVALID_COMMAND;
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int do_prevent_allow(struct fsg_common *common)
+{
+	struct fsg_lun	*curlun = &common->luns[common->lun];
+	int		prevent;
+
+	if (!curlun->removable) {
+		curlun->sense_data = SS_INVALID_COMMAND;
+		return -EINVAL;
+	}
+
+	prevent = common->cmnd[4] & 0x01;
+	if ((common->cmnd[4] & ~0x01) != 0) {	/* Mask away Prevent */
+		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
+		return -EINVAL;
+	}
+
+	if (curlun->prevent_medium_removal && !prevent)
+		fsg_lun_fsync_sub(curlun);
+	curlun->prevent_medium_removal = prevent;
+	return 0;
+}
+
+
+static int do_read_format_capacities(struct fsg_common *common,
+			struct fsg_buffhd *bh)
+{
+	struct fsg_lun	*curlun = &common->luns[common->lun];
+	u8		*buf = (u8 *) bh->buf;
+
+	buf[0] = buf[1] = buf[2] = 0;
+	buf[3] = 8;	/* Only the Current/Maximum Capacity Descriptor */
+	buf += 4;
+
+	put_unaligned_be32(curlun->num_sectors, &buf[0]);
+						/* Number of blocks */
+	put_unaligned_be32(512, &buf[4]);	/* Block length */
+	buf[4] = 0x02;				/* Current capacity */
+	return 12;
+}
+
+
+static int do_mode_select(struct fsg_common *common, struct fsg_buffhd *bh)
+{
+	struct fsg_lun	*curlun = &common->luns[common->lun];
+
+	/* We don't support MODE SELECT */
+	if (curlun)
+		curlun->sense_data = SS_INVALID_COMMAND;
+	return -EINVAL;
+}
+
+
+/*-------------------------------------------------------------------------*/
+
+static int halt_bulk_in_endpoint(struct fsg_dev *fsg)
+{
+	int	rc;
+
+	rc = fsg_set_halt(fsg, fsg->bulk_in);
+	if (rc == -EAGAIN)
+		VDBG(fsg, "delayed bulk-in endpoint halt\n");
+	while (rc != 0) {
+		if (rc != -EAGAIN) {
+			WARNING(fsg, "usb_ep_set_halt -> %d\n", rc);
+			rc = 0;
+			break;
+		}
+
+		rc = usb_ep_set_halt(fsg->bulk_in);
+	}
+	return rc;
+}
+
+static int wedge_bulk_in_endpoint(struct fsg_dev *fsg)
+{
+	int	rc;
+
+	DBG(fsg, "bulk-in set wedge\n");
+	rc = 0; /* usb_ep_set_wedge(fsg->bulk_in); */
+	if (rc == -EAGAIN)
+		VDBG(fsg, "delayed bulk-in endpoint wedge\n");
+	while (rc != 0) {
+		if (rc != -EAGAIN) {
+			WARNING(fsg, "usb_ep_set_wedge -> %d\n", rc);
+			rc = 0;
+			break;
+		}
+	}
+	return rc;
+}
+
+static int pad_with_zeros(struct fsg_dev *fsg)
+{
+	struct fsg_buffhd	*bh = fsg->common->next_buffhd_to_fill;
+	u32			nkeep = bh->inreq->length;
+	u32			nsend;
+	int			rc;
+
+	bh->state = BUF_STATE_EMPTY;		/* For the first iteration */
+	fsg->common->usb_amount_left = nkeep + fsg->common->residue;
+	while (fsg->common->usb_amount_left > 0) {
+
+		/* Wait for the next buffer to be free */
+		while (bh->state != BUF_STATE_EMPTY) {
+			rc = sleep_thread(fsg->common);
+			if (rc)
+				return rc;
+		}
+
+		nsend = min(fsg->common->usb_amount_left, FSG_BUFLEN);
+		memset(bh->buf + nkeep, 0, nsend - nkeep);
+		bh->inreq->length = nsend;
+		bh->inreq->zero = 0;
+		start_transfer(fsg, fsg->bulk_in, bh->inreq,
+				&bh->inreq_busy, &bh->state);
+		bh = fsg->common->next_buffhd_to_fill = bh->next;
+		fsg->common->usb_amount_left -= nsend;
+		nkeep = 0;
+	}
+	return 0;
+}
+
+static int throw_away_data(struct fsg_common *common)
+{
+	struct fsg_buffhd	*bh;
+	u32			amount;
+	int			rc;
+
+	for (bh = common->next_buffhd_to_drain;
+	     bh->state != BUF_STATE_EMPTY || common->usb_amount_left > 0;
+	     bh = common->next_buffhd_to_drain) {
+
+		/* Throw away the data in a filled buffer */
+		if (bh->state == BUF_STATE_FULL) {
+			bh->state = BUF_STATE_EMPTY;
+			common->next_buffhd_to_drain = bh->next;
+
+			/* A short packet or an error ends everything */
+			if (bh->outreq->actual != bh->outreq->length ||
+					bh->outreq->status != 0) {
+				raise_exception(common,
+						FSG_STATE_ABORT_BULK_OUT);
+				return -EPIPE;
+			}
+			continue;
+		}
+
+		/* Try to submit another request if we need one */
+		bh = common->next_buffhd_to_fill;
+		if (bh->state == BUF_STATE_EMPTY
+		 && common->usb_amount_left > 0) {
+			amount = min(common->usb_amount_left, FSG_BUFLEN);
+
+			/* amount is always divisible by 512, hence by
+			 * the bulk-out maxpacket size */
+			bh->outreq->length = amount;
+			bh->bulk_out_intended_length = amount;
+			bh->outreq->short_not_ok = 1;
+			START_TRANSFER_OR(common, bulk_out, bh->outreq,
+					  &bh->outreq_busy, &bh->state)
+				/* Don't know what to do if
+				 * common->fsg is NULL */
+				return -EIO;
+			common->next_buffhd_to_fill = bh->next;
+			common->usb_amount_left -= amount;
+			continue;
+		}
+
+		/* Otherwise wait for something to happen */
+		rc = sleep_thread(common);
+		if (rc)
+			return rc;
+	}
+	return 0;
+}
+
+
+static int finish_reply(struct fsg_common *common)
+{
+	struct fsg_buffhd	*bh = common->next_buffhd_to_fill;
+	int			rc = 0;
+
+	switch (common->data_dir) {
+	case DATA_DIR_NONE:
+		break;			/* Nothing to send */
+
+	/* If we don't know whether the host wants to read or write,
+	 * this must be CB or CBI with an unknown command.  We mustn't
+	 * try to send or receive any data.  So stall both bulk pipes
+	 * if we can and wait for a reset. */
+	case DATA_DIR_UNKNOWN:
+		if (!common->can_stall) {
+			/* Nothing */
+		} else if (fsg_is_set(common)) {
+			fsg_set_halt(common->fsg, common->fsg->bulk_out);
+			rc = halt_bulk_in_endpoint(common->fsg);
+		} else {
+			/* Don't know what to do if common->fsg is NULL */
+			rc = -EIO;
+		}
+		break;
+
+	/* All but the last buffer of data must have already been sent */
+	case DATA_DIR_TO_HOST:
+		if (common->data_size == 0) {
+			/* Nothing to send */
+
+		/* If there's no residue, simply send the last buffer */
+		} else if (common->residue == 0) {
+			bh->inreq->zero = 0;
+			START_TRANSFER_OR(common, bulk_in, bh->inreq,
+					  &bh->inreq_busy, &bh->state)
+				return -EIO;
+			common->next_buffhd_to_fill = bh->next;
+
+		/* For Bulk-only, if we're allowed to stall then send the
+		 * short packet and halt the bulk-in endpoint.  If we can't
+		 * stall, pad out the remaining data with 0's. */
+		} else if (common->can_stall) {
+			bh->inreq->zero = 1;
+			START_TRANSFER_OR(common, bulk_in, bh->inreq,
+					  &bh->inreq_busy, &bh->state)
+				/* Don't know what to do if
+				 * common->fsg is NULL */
+				rc = -EIO;
+			common->next_buffhd_to_fill = bh->next;
+			if (common->fsg)
+				rc = halt_bulk_in_endpoint(common->fsg);
+		} else if (fsg_is_set(common)) {
+			rc = pad_with_zeros(common->fsg);
+		} else {
+			/* Don't know what to do if common->fsg is NULL */
+			rc = -EIO;
+		}
+		break;
+
+	/* We have processed all we want from the data the host has sent.
+	 * There may still be outstanding bulk-out requests. */
+	case DATA_DIR_FROM_HOST:
+		if (common->residue == 0) {
+			/* Nothing to receive */
+
+		/* Did the host stop sending unexpectedly early? */
+		} else if (common->short_packet_received) {
+			raise_exception(common, FSG_STATE_ABORT_BULK_OUT);
+			rc = -EPIPE;
+
+		/* We haven't processed all the incoming data.  Even though
+		 * we may be allowed to stall, doing so would cause a race.
+		 * The controller may already have ACK'ed all the remaining
+		 * bulk-out packets, in which case the host wouldn't see a
+		 * STALL.  Not realizing the endpoint was halted, it wouldn't
+		 * clear the halt -- leading to problems later on. */
+#if 0
+		} else if (common->can_stall) {
+			if (fsg_is_set(common))
+				fsg_set_halt(common->fsg,
+					     common->fsg->bulk_out);
+			raise_exception(common, FSG_STATE_ABORT_BULK_OUT);
+			rc = -EPIPE;
+#endif
+
+		/* We can't stall.  Read in the excess data and throw it
+		 * all away. */
+		} else {
+			rc = throw_away_data(common);
+		}
+		break;
+	}
+	return rc;
+}
+
+
+static int send_status(struct fsg_common *common)
+{
+	struct fsg_lun		*curlun = &common->luns[common->lun];
+	struct fsg_buffhd	*bh;
+	struct bulk_cs_wrap	*csw;
+	int			rc;
+	u8			status = US_BULK_STAT_OK;
+	u32			sd, sdinfo = 0;
+
+	/* Wait for the next buffer to become available */
+	bh = common->next_buffhd_to_fill;
+	while (bh->state != BUF_STATE_EMPTY) {
+		rc = sleep_thread(common);
+		if (rc)
+			return rc;
+	}
+
+	if (curlun)
+		sd = curlun->sense_data;
+	else if (common->bad_lun_okay)
+		sd = SS_NO_SENSE;
+	else
+		sd = SS_LOGICAL_UNIT_NOT_SUPPORTED;
+
+	if (common->phase_error) {
+		DBG(common, "sending phase-error status\n");
+		status = US_BULK_STAT_PHASE;
+		sd = SS_INVALID_COMMAND;
+	} else if (sd != SS_NO_SENSE) {
+		DBG(common, "sending command-failure status\n");
+		status = US_BULK_STAT_FAIL;
+		VDBG(common, "  sense data: SK x%02x, ASC x%02x, ASCQ x%02x;"
+			"  info x%x\n",
+			SK(sd), ASC(sd), ASCQ(sd), sdinfo);
+	}
+
+	/* Store and send the Bulk-only CSW */
+	csw = (void *)bh->buf;
+
+	csw->Signature = cpu_to_le32(US_BULK_CS_SIGN);
+	csw->Tag = common->tag;
+	csw->Residue = cpu_to_le32(common->residue);
+	csw->Status = status;
+
+	bh->inreq->length = US_BULK_CS_WRAP_LEN;
+	bh->inreq->zero = 0;
+	START_TRANSFER_OR(common, bulk_in, bh->inreq,
+			  &bh->inreq_busy, &bh->state)
+		/* Don't know what to do if common->fsg is NULL */
+		return -EIO;
+
+	common->next_buffhd_to_fill = bh->next;
+	return 0;
+}
+
+
+/*-------------------------------------------------------------------------*/
+
+/* Check whether the command is properly formed and whether its data size
+ * and direction agree with the values we already have. */
+static int check_command(struct fsg_common *common, int cmnd_size,
+		enum data_direction data_dir, unsigned int mask,
+		int needs_medium, const char *name)
+{
+	int			i;
+	int			lun = common->cmnd[1] >> 5;
+	static const char	dirletter[4] = {'u', 'o', 'i', 'n'};
+	char			hdlen[20];
+	struct fsg_lun		*curlun;
+
+	hdlen[0] = 0;
+	if (common->data_dir != DATA_DIR_UNKNOWN)
+		sprintf(hdlen, ", H%c=%u", dirletter[(int) common->data_dir],
+				common->data_size);
+	VDBG(common, "SCSI command: %s;  Dc=%d, D%c=%u;  Hc=%d%s\n",
+	     name, cmnd_size, dirletter[(int) data_dir],
+	     common->data_size_from_cmnd, common->cmnd_size, hdlen);
+
+	/* We can't reply at all until we know the correct data direction
+	 * and size. */
+	if (common->data_size_from_cmnd == 0)
+		data_dir = DATA_DIR_NONE;
+	if (common->data_size < common->data_size_from_cmnd) {
+		/* Host data size < Device data size is a phase error.
+		 * Carry out the command, but only transfer as much as
+		 * we are allowed. */
+		common->data_size_from_cmnd = common->data_size;
+		common->phase_error = 1;
+	}
+	common->residue = common->data_size;
+	common->usb_amount_left = common->data_size;
+
+	/* Conflicting data directions is a phase error */
+	if (common->data_dir != data_dir
+	 && common->data_size_from_cmnd > 0) {
+		common->phase_error = 1;
+		return -EINVAL;
+	}
+
+	/* Verify the length of the command itself */
+	if (cmnd_size != common->cmnd_size) {
+
+		/* Special case workaround: There are plenty of buggy SCSI
+		 * implementations. Many have issues with cbw->Length
+		 * field passing a wrong command size. For those cases we
+		 * always try to work around the problem by using the length
+		 * sent by the host side provided it is at least as large
+		 * as the correct command length.
+		 * Examples of such cases would be MS-Windows, which issues
+		 * REQUEST SENSE with cbw->Length == 12 where it should
+		 * be 6, and xbox360 issuing INQUIRY, TEST UNIT READY and
+		 * REQUEST SENSE with cbw->Length == 10 where it should
+		 * be 6 as well.
+		 */
+		if (cmnd_size <= common->cmnd_size) {
+			DBG(common, "%s is buggy! Expected length %d "
+			    "but we got %d\n", name,
+			    cmnd_size, common->cmnd_size);
+			cmnd_size = common->cmnd_size;
+		} else {
+			common->phase_error = 1;
+			return -EINVAL;
+		}
+	}
+
+	/* Check that the LUN values are consistent */
+	if (common->lun != lun)
+		DBG(common, "using LUN %d from CBW, not LUN %d from CDB\n",
+		    common->lun, lun);
+
+	/* Check the LUN */
+	if (common->lun < common->nluns) {
+		curlun = &common->luns[common->lun];
+		if (common->cmnd[0] != SCSI_REQ_SENSE) {
+			curlun->sense_data = SS_NO_SENSE;
+			curlun->info_valid = 0;
+		}
+	} else {
+		curlun = NULL;
+		common->bad_lun_okay = 0;
+
+		/* INQUIRY and REQUEST SENSE commands are explicitly allowed
+		 * to use unsupported LUNs; all others may not. */
+		if (common->cmnd[0] != SCSI_INQUIRY &&
+		    common->cmnd[0] != SCSI_REQ_SENSE) {
+			DBG(common, "unsupported LUN %d\n", common->lun);
+			return -EINVAL;
+		}
+	}
+#if 0
+	/* If a unit attention condition exists, only INQUIRY and
+	 * REQUEST SENSE commands are allowed; anything else must fail. */
+	if (curlun && curlun->unit_attention_data != SS_NO_SENSE &&
+			common->cmnd[0] != SCSI_INQUIRY &&
+			common->cmnd[0] != SCSI_REQ_SENSE) {
+		curlun->sense_data = curlun->unit_attention_data;
+		curlun->unit_attention_data = SS_NO_SENSE;
+		return -EINVAL;
+	}
+#endif
+	/* Check that only command bytes listed in the mask are non-zero */
+	common->cmnd[1] &= 0x1f;			/* Mask away the LUN */
+	for (i = 1; i < cmnd_size; ++i) {
+		if (common->cmnd[i] && !(mask & (1 << i))) {
+			if (curlun)
+				curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static int do_scsi_command(struct fsg_common *common)
+{
+	struct fsg_buffhd	*bh;
+	int			rc;
+	int			reply = -EINVAL;
+	int			i;
+	static char		unknown[16];
+	struct fsg_lun		*curlun = &common->luns[common->lun];
+
+	dump_cdb(common);
+
+	/* Wait for the next buffer to become available for data or status */
+	bh = common->next_buffhd_to_fill;
+	common->next_buffhd_to_drain = bh;
+	while (bh->state != BUF_STATE_EMPTY) {
+		rc = sleep_thread(common);
+		if (rc)
+			return rc;
+	}
+	common->phase_error = 0;
+	common->short_packet_received = 0;
+
+	down_read(&common->filesem);	/* We're using the backing file */
+	switch (common->cmnd[0]) {
+
+	case SCSI_INQUIRY:
+		common->data_size_from_cmnd = common->cmnd[4];
+		reply = check_command(common, 6, DATA_DIR_TO_HOST,
+				      (1<<4), 0,
+				      "INQUIRY");
+		if (reply == 0)
+			reply = do_inquiry(common, bh);
+		break;
+
+	case SCSI_MODE_SEL6:
+		common->data_size_from_cmnd = common->cmnd[4];
+		reply = check_command(common, 6, DATA_DIR_FROM_HOST,
+				      (1<<1) | (1<<4), 0,
+				      "MODE SELECT(6)");
+		if (reply == 0)
+			reply = do_mode_select(common, bh);
+		break;
+
+	case SCSI_MODE_SEL10:
+		common->data_size_from_cmnd =
+			get_unaligned_be16(&common->cmnd[7]);
+		reply = check_command(common, 10, DATA_DIR_FROM_HOST,
+				      (1<<1) | (3<<7), 0,
+				      "MODE SELECT(10)");
+		if (reply == 0)
+			reply = do_mode_select(common, bh);
+		break;
+
+	case SCSI_MODE_SEN6:
+		common->data_size_from_cmnd = common->cmnd[4];
+		reply = check_command(common, 6, DATA_DIR_TO_HOST,
+				      (1<<1) | (1<<2) | (1<<4), 0,
+				      "MODE SENSE(6)");
+		if (reply == 0)
+			reply = do_mode_sense(common, bh);
+		break;
+
+	case SCSI_MODE_SEN10:
+		common->data_size_from_cmnd =
+			get_unaligned_be16(&common->cmnd[7]);
+		reply = check_command(common, 10, DATA_DIR_TO_HOST,
+				      (1<<1) | (1<<2) | (3<<7), 0,
+				      "MODE SENSE(10)");
+		if (reply == 0)
+			reply = do_mode_sense(common, bh);
+		break;
+
+	case SCSI_MED_REMOVL:
+		common->data_size_from_cmnd = 0;
+		reply = check_command(common, 6, DATA_DIR_NONE,
+				      (1<<4), 0,
+				      "PREVENT-ALLOW MEDIUM REMOVAL");
+		if (reply == 0)
+			reply = do_prevent_allow(common);
+		break;
+
+	case SCSI_READ6:
+		i = common->cmnd[4];
+		common->data_size_from_cmnd = (i == 0 ? 256 : i) << 9;
+		reply = check_command(common, 6, DATA_DIR_TO_HOST,
+				      (7<<1) | (1<<4), 1,
+				      "READ(6)");
+		if (reply == 0)
+			reply = do_read(common);
+		break;
+
+	case SCSI_READ10:
+		common->data_size_from_cmnd =
+				get_unaligned_be16(&common->cmnd[7]) << 9;
+		reply = check_command(common, 10, DATA_DIR_TO_HOST,
+				      (1<<1) | (0xf<<2) | (3<<7), 1,
+				      "READ(10)");
+		if (reply == 0)
+			reply = do_read(common);
+		break;
+
+	case SCSI_READ12:
+		common->data_size_from_cmnd =
+				get_unaligned_be32(&common->cmnd[6]) << 9;
+		reply = check_command(common, 12, DATA_DIR_TO_HOST,
+				      (1<<1) | (0xf<<2) | (0xf<<6), 1,
+				      "READ(12)");
+		if (reply == 0)
+			reply = do_read(common);
+		break;
+
+	case SCSI_RD_CAPAC:
+		common->data_size_from_cmnd = 8;
+		reply = check_command(common, 10, DATA_DIR_TO_HOST,
+				      (0xf<<2) | (1<<8), 1,
+				      "READ CAPACITY");
+		if (reply == 0)
+			reply = do_read_capacity(common, bh);
+		break;
+
+	case SCSI_RD_HEADER:
+		if (!common->luns[common->lun].cdrom)
+			goto unknown_cmnd;
+		common->data_size_from_cmnd =
+			get_unaligned_be16(&common->cmnd[7]);
+		reply = check_command(common, 10, DATA_DIR_TO_HOST,
+				      (3<<7) | (0x1f<<1), 1,
+				      "READ HEADER");
+		if (reply == 0)
+			reply = do_read_header(common, bh);
+		break;
+
+	case SCSI_RD_TOC:
+		if (!common->luns[common->lun].cdrom)
+			goto unknown_cmnd;
+		common->data_size_from_cmnd =
+			get_unaligned_be16(&common->cmnd[7]);
+		reply = check_command(common, 10, DATA_DIR_TO_HOST,
+				      (7<<6) | (1<<1), 1,
+				      "READ TOC");
+		if (reply == 0)
+			reply = do_read_toc(common, bh);
+		break;
+
+	case SCSI_RD_FMT_CAPAC:
+		common->data_size_from_cmnd =
+			get_unaligned_be16(&common->cmnd[7]);
+		reply = check_command(common, 10, DATA_DIR_TO_HOST,
+				      (3<<7), 1,
+				      "READ FORMAT CAPACITIES");
+		if (reply == 0)
+			reply = do_read_format_capacities(common, bh);
+		break;
+
+	case SCSI_REQ_SENSE:
+		common->data_size_from_cmnd = common->cmnd[4];
+		reply = check_command(common, 6, DATA_DIR_TO_HOST,
+				      (1<<4), 0,
+				      "REQUEST SENSE");
+		if (reply == 0)
+			reply = do_request_sense(common, bh);
+		break;
+
+	case SCSI_START_STP:
+		common->data_size_from_cmnd = 0;
+		reply = check_command(common, 6, DATA_DIR_NONE,
+				      (1<<1) | (1<<4), 0,
+				      "START-STOP UNIT");
+		if (reply == 0)
+			reply = do_start_stop(common);
+		break;
+
+	case SCSI_SYNC_CACHE:
+		common->data_size_from_cmnd = 0;
+		reply = check_command(common, 10, DATA_DIR_NONE,
+				      (0xf<<2) | (3<<7), 1,
+				      "SYNCHRONIZE CACHE");
+		if (reply == 0)
+			reply = do_synchronize_cache(common);
+		break;
+
+	case SCSI_TST_U_RDY:
+		common->data_size_from_cmnd = 0;
+		reply = check_command(common, 6, DATA_DIR_NONE,
+				0, 1,
+				"TEST UNIT READY");
+		break;
+
+	/* Although optional, this command is used by MS-Windows.  We
+	 * support a minimal version: BytChk must be 0. */
+	case SCSI_VERIFY:
+		common->data_size_from_cmnd = 0;
+		reply = check_command(common, 10, DATA_DIR_NONE,
+				      (1<<1) | (0xf<<2) | (3<<7), 1,
+				      "VERIFY");
+		if (reply == 0)
+			reply = do_verify(common);
+		break;
+
+	case SCSI_WRITE6:
+		i = common->cmnd[4];
+		common->data_size_from_cmnd = (i == 0 ? 256 : i) << 9;
+		reply = check_command(common, 6, DATA_DIR_FROM_HOST,
+				      (7<<1) | (1<<4), 1,
+				      "WRITE(6)");
+		if (reply == 0)
+			reply = do_write(common);
+		break;
+
+	case SCSI_WRITE10:
+		common->data_size_from_cmnd =
+				get_unaligned_be16(&common->cmnd[7]) << 9;
+		reply = check_command(common, 10, DATA_DIR_FROM_HOST,
+				      (1<<1) | (0xf<<2) | (3<<7), 1,
+				      "WRITE(10)");
+		if (reply == 0)
+			reply = do_write(common);
+		break;
+
+	case SCSI_WRITE12:
+		common->data_size_from_cmnd =
+				get_unaligned_be32(&common->cmnd[6]) << 9;
+		reply = check_command(common, 12, DATA_DIR_FROM_HOST,
+				      (1<<1) | (0xf<<2) | (0xf<<6), 1,
+				      "WRITE(12)");
+		if (reply == 0)
+			reply = do_write(common);
+		break;
+
+	/* Some mandatory commands that we recognize but don't implement.
+	 * They don't mean much in this setting.  It's left as an exercise
+	 * for anyone interested to implement RESERVE and RELEASE in terms
+	 * of Posix locks. */
+	case SCSI_FORMAT:
+	case SCSI_RELEASE:
+	case SCSI_RESERVE:
+	case SCSI_SEND_DIAG:
+		/* Fall through */
+
+	default:
+unknown_cmnd:
+		common->data_size_from_cmnd = 0;
+		sprintf(unknown, "Unknown x%02x", common->cmnd[0]);
+		reply = check_command(common, common->cmnd_size,
+				      DATA_DIR_UNKNOWN, 0xff, 0, unknown);
+		if (reply == 0) {
+			curlun->sense_data = SS_INVALID_COMMAND;
+			reply = -EINVAL;
+		}
+		break;
+	}
+	up_read(&common->filesem);
+
+	if (reply == -EPIPE)
+		return -EPIPE;
+
+	/* Set up the single reply buffer for finish_reply() */
+	if (reply == -EINVAL)
+		reply = 0;		/* Error reply length */
+	if (reply >= 0 && common->data_dir == DATA_DIR_TO_HOST) {
+		reply = min((u32) reply, common->data_size_from_cmnd);
+		bh->inreq->length = reply;
+		bh->state = BUF_STATE_FULL;
+		common->residue -= reply;
+	}				/* Otherwise it's already set */
+
+	return 0;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int received_cbw(struct fsg_dev *fsg, struct fsg_buffhd *bh)
+{
+	struct usb_request	*req = bh->outreq;
+	struct bulk_cb_wrap	*cbw = req->buf;
+	struct fsg_common	*common = fsg->common;
+
+	/* Was this a real packet?  Should it be ignored? */
+	if (req->status || test_bit(IGNORE_BULK_OUT, &fsg->atomic_bitflags))
+		return -EINVAL;
+
+	/* Is the CBW valid? */
+	if (req->actual != US_BULK_CB_WRAP_LEN ||
+			cbw->Signature != cpu_to_le32(
+				US_BULK_CB_SIGN)) {
+		DBG(fsg, "invalid CBW: len %u sig 0x%x\n",
+				req->actual,
+				le32_to_cpu(cbw->Signature));
+
+		/* The Bulk-only spec says we MUST stall the IN endpoint
+		 * (6.6.1), so it's unavoidable.  It also says we must
+		 * retain this state until the next reset, but there's
+		 * no way to tell the controller driver it should ignore
+		 * Clear-Feature(HALT) requests.
+		 *
+		 * We aren't required to halt the OUT endpoint; instead
+		 * we can simply accept and discard any data received
+		 * until the next reset. */
+		wedge_bulk_in_endpoint(fsg);
+		set_bit(IGNORE_BULK_OUT, &fsg->atomic_bitflags);
+		return -EINVAL;
+	}
+
+	/* Is the CBW meaningful? */
+	if (cbw->Lun >= FSG_MAX_LUNS || cbw->Flags & ~US_BULK_FLAG_IN ||
+			cbw->Length <= 0 || cbw->Length > MAX_COMMAND_SIZE) {
+		DBG(fsg, "non-meaningful CBW: lun = %u, flags = 0x%x, "
+				"cmdlen %u\n",
+				cbw->Lun, cbw->Flags, cbw->Length);
+
+		/* We can do anything we want here, so let's stall the
+		 * bulk pipes if we are allowed to. */
+		if (common->can_stall) {
+			fsg_set_halt(fsg, fsg->bulk_out);
+			halt_bulk_in_endpoint(fsg);
+		}
+		return -EINVAL;
+	}
+
+	/* Save the command for later */
+	common->cmnd_size = cbw->Length;
+	memcpy(common->cmnd, cbw->CDB, common->cmnd_size);
+	if (cbw->Flags & US_BULK_FLAG_IN)
+		common->data_dir = DATA_DIR_TO_HOST;
+	else
+		common->data_dir = DATA_DIR_FROM_HOST;
+	common->data_size = le32_to_cpu(cbw->DataTransferLength);
+	if (common->data_size == 0)
+		common->data_dir = DATA_DIR_NONE;
+	common->lun = cbw->Lun;
+	common->tag = cbw->Tag;
+	return 0;
+}
+
+
+static int get_next_command(struct fsg_common *common)
+{
+	struct fsg_buffhd	*bh;
+	int			rc = 0;
+
+	/* Wait for the next buffer to become available */
+	bh = common->next_buffhd_to_fill;
+	while (bh->state != BUF_STATE_EMPTY) {
+		rc = sleep_thread(common);
+		if (rc)
+			return rc;
+	}
+
+	/* Queue a request to read a Bulk-only CBW */
+	set_bulk_out_req_length(common, bh, US_BULK_CB_WRAP_LEN);
+	bh->outreq->short_not_ok = 1;
+	START_TRANSFER_OR(common, bulk_out, bh->outreq,
+			  &bh->outreq_busy, &bh->state)
+		/* Don't know what to do if common->fsg is NULL */
+		return -EIO;
+
+	/* We will drain the buffer in software, which means we
+	 * can reuse it for the next filling.  No need to advance
+	 * next_buffhd_to_fill. */
+
+	/* Wait for the CBW to arrive */
+	while (bh->state != BUF_STATE_FULL) {
+		rc = sleep_thread(common);
+		if (rc)
+			return rc;
+	}
+
+	rc = fsg_is_set(common) ? received_cbw(common->fsg, bh) : -EIO;
+	bh->state = BUF_STATE_EMPTY;
+
+	return rc;
+}
+
+
+/*-------------------------------------------------------------------------*/
+
+static int enable_endpoint(struct fsg_common *common, struct usb_ep *ep)
+{
+	int	rc;
+
+	ep->driver_data = common;
+	rc = usb_ep_enable(ep);
+	if (rc)
+		ERROR(common, "can't enable %s, result %d\n", ep->name, rc);
+	return rc;
+}
+
+static int alloc_request(struct fsg_common *common, struct usb_ep *ep,
+		struct usb_request **preq)
+{
+	*preq = usb_ep_alloc_request(ep);
+	if (*preq)
+		return 0;
+	ERROR(common, "can't allocate request for %s\n", ep->name);
+	return -ENOMEM;
+}
+
+/* Reset interface setting and re-init endpoint state (toggle etc). */
+static int do_set_interface(struct fsg_common *common, struct fsg_dev *new_fsg)
+{
+	struct fsg_dev *fsg;
+	int i, rc = 0;
+
+	if (common->running)
+		DBG(common, "reset interface\n");
+
+reset:
+	/* Deallocate the requests */
+	if (common->fsg) {
+		fsg = common->fsg;
+
+		for (i = 0; i < FSG_NUM_BUFFERS; ++i) {
+			struct fsg_buffhd *bh = &common->buffhds[i];
+
+			if (bh->inreq) {
+				usb_ep_free_request(fsg->bulk_in, bh->inreq);
+				bh->inreq = NULL;
+			}
+			if (bh->outreq) {
+				usb_ep_free_request(fsg->bulk_out, bh->outreq);
+				bh->outreq = NULL;
+			}
+		}
+
+		/* Disable the endpoints */
+		if (fsg->bulk_in_enabled) {
+			usb_ep_disable(fsg->bulk_in);
+			fsg->bulk_in_enabled = 0;
+		}
+		if (fsg->bulk_out_enabled) {
+			usb_ep_disable(fsg->bulk_out);
+			fsg->bulk_out_enabled = 0;
+		}
+
+		common->fsg = NULL;
+	}
+
+	common->running = 0;
+	if (!new_fsg || rc)
+		return rc;
+
+	common->fsg = new_fsg;
+	fsg = common->fsg;
+
+	/* Enable the endpoints */
+	fsg->bulk_in->desc = fsg_ep_desc(common->gadget,
+					 &fsg_fs_bulk_in_desc, &fsg_hs_bulk_in_desc);
+	rc = enable_endpoint(common, fsg->bulk_in);
+	if (rc)
+		goto reset;
+	fsg->bulk_in_enabled = 1;
+
+	fsg->bulk_out->desc = fsg_ep_desc(common->gadget,
+					  &fsg_fs_bulk_out_desc, &fsg_hs_bulk_out_desc);
+	rc = enable_endpoint(common, fsg->bulk_out);
+	if (rc)
+		goto reset;
+	fsg->bulk_out_enabled = 1;
+	common->bulk_out_maxpacket = 512;
+	clear_bit(IGNORE_BULK_OUT, &fsg->atomic_bitflags);
+
+	/* Allocate the requests */
+	for (i = 0; i < FSG_NUM_BUFFERS; ++i) {
+		struct fsg_buffhd	*bh = &common->buffhds[i];
+
+		rc = alloc_request(common, fsg->bulk_in, &bh->inreq);
+		if (rc)
+			goto reset;
+		rc = alloc_request(common, fsg->bulk_out, &bh->outreq);
+		if (rc)
+			goto reset;
+		bh->inreq->buf = bh->outreq->buf = bh->buf;
+		bh->inreq->context = bh->outreq->context = bh;
+		bh->inreq->complete = bulk_in_complete;
+		bh->outreq->complete = bulk_out_complete;
+	}
+
+	common->running = 1;
+
+	return rc;
+}
+
+
+/****************************** ALT CONFIGS ******************************/
+
+
+static int fsg_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
+{
+	struct fsg_dev *fsg = fsg_from_func(f);
+	fsg->common->new_fsg = fsg;
+	raise_exception(fsg->common, FSG_STATE_CONFIG_CHANGE);
+	return 0;
+}
+
+static void fsg_disable(struct usb_function *f)
+{
+	struct fsg_dev *fsg = fsg_from_func(f);
+	fsg->common->new_fsg = NULL;
+	raise_exception(fsg->common, FSG_STATE_CONFIG_CHANGE);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static void handle_exception(struct fsg_common *common)
+{
+	int			i;
+	struct fsg_buffhd	*bh;
+	enum fsg_state		old_state;
+	struct fsg_lun		*curlun;
+	unsigned int		exception_req_tag;
+
+	/* Cancel all the pending transfers */
+	if (common->fsg) {
+		for (i = 0; i < FSG_NUM_BUFFERS; ++i) {
+			bh = &common->buffhds[i];
+			if (bh->inreq_busy)
+				usb_ep_dequeue(common->fsg->bulk_in, bh->inreq);
+			if (bh->outreq_busy)
+				usb_ep_dequeue(common->fsg->bulk_out,
+					       bh->outreq);
+		}
+
+		/* Wait until everything is idle */
+		for (;;) {
+			int num_active = 0;
+			for (i = 0; i < FSG_NUM_BUFFERS; ++i) {
+				bh = &common->buffhds[i];
+				num_active += bh->inreq_busy + bh->outreq_busy;
+			}
+			if (num_active == 0)
+				break;
+			if (sleep_thread(common))
+				return;
+		}
+
+		/* Clear out the controller's fifos */
+		if (common->fsg->bulk_in_enabled)
+			usb_ep_fifo_flush(common->fsg->bulk_in);
+		if (common->fsg->bulk_out_enabled)
+			usb_ep_fifo_flush(common->fsg->bulk_out);
+	}
+
+	/* Reset the I/O buffer states and pointers, the SCSI
+	 * state, and the exception.  Then invoke the handler. */
+
+	for (i = 0; i < FSG_NUM_BUFFERS; ++i) {
+		bh = &common->buffhds[i];
+		bh->state = BUF_STATE_EMPTY;
+	}
+	common->next_buffhd_to_fill = &common->buffhds[0];
+	common->next_buffhd_to_drain = &common->buffhds[0];
+	exception_req_tag = common->exception_req_tag;
+	old_state = common->state;
+
+	report_exception("handling", old_state);
+
+	if (old_state == FSG_STATE_ABORT_BULK_OUT)
+		common->state = FSG_STATE_STATUS_PHASE;
+	else {
+		for (i = 0; i < common->nluns; ++i) {
+			curlun = &common->luns[i];
+			curlun->sense_data = SS_NO_SENSE;
+			curlun->info_valid = 0;
+		}
+		common->state = FSG_STATE_IDLE;
+	}
+
+	/* Carry out any extra actions required for the exception */
+	switch (old_state) {
+	case FSG_STATE_ABORT_BULK_OUT:
+		send_status(common);
+
+		if (common->state == FSG_STATE_STATUS_PHASE)
+			common->state = FSG_STATE_IDLE;
+		break;
+
+	case FSG_STATE_RESET:
+		/* In case we were forced against our will to halt a
+		 * bulk endpoint, clear the halt now.  (The SuperH UDC
+		 * requires this.) */
+		if (!fsg_is_set(common))
+			break;
+		if (test_and_clear_bit(IGNORE_BULK_OUT,
+				       &common->fsg->atomic_bitflags))
+			usb_ep_clear_halt(common->fsg->bulk_in);
+
+		if (common->ep0_req_tag == exception_req_tag)
+			ep0_queue(common);	/* Complete the status stage */
+
+		break;
+
+	case FSG_STATE_CONFIG_CHANGE:
+		do_set_interface(common, common->new_fsg);
+		break;
+
+	case FSG_STATE_EXIT:
+	case FSG_STATE_TERMINATED:
+		do_set_interface(common, NULL);		/* Free resources */
+		common->state = FSG_STATE_TERMINATED;	/* Stop the thread */
+		break;
+
+	case FSG_STATE_INTERFACE_CHANGE:
+	case FSG_STATE_DISCONNECT:
+	case FSG_STATE_COMMAND_PHASE:
+	case FSG_STATE_DATA_PHASE:
+	case FSG_STATE_STATUS_PHASE:
+	case FSG_STATE_IDLE:
+		break;
+	}
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int fsg_main_thread(void *common_)
+{
+	struct fsg_common	*common = common_;
+	int ret = 0;
+
+	/* The main loop */
+	while (common->state != FSG_STATE_TERMINATED) {
+		if (exception_in_progress(common)) {
+			handle_exception(common);
+			continue;
+		}
+
+		if (!common->running) {
+			ret = sleep_thread(common);
+			if (ret)
+				break;
+			continue;
+		}
+
+		ret = get_next_command(common);
+		if (ret)
+			continue;
+
+		if (!exception_in_progress(common))
+			common->state = FSG_STATE_DATA_PHASE;
+
+		if (do_scsi_command(common) || finish_reply(common))
+			continue;
+
+		if (!exception_in_progress(common))
+			common->state = FSG_STATE_STATUS_PHASE;
+
+		if (send_status(common))
+			continue;
+
+		if (!exception_in_progress(common))
+			common->state = FSG_STATE_IDLE;
+	}
+
+	if (ret && ret != -ERESTARTSYS) {
+		pr_warn("%s: error %pe\n", __func__, ERR_PTR(ret));
+		return ret;
+	}
+
+	return 0;
+}
+
+static void fsg_common_release(struct fsg_common *common);
+
+static struct fsg_common *fsg_common_setup(void)
+{
+	struct fsg_common *common;
+
+	/* Allocate? */
+	common = calloc(sizeof(*common), 1);
+	if (!common)
+		return NULL;
+
+	common->ops = NULL;
+	common->private_data = NULL;
+
+	return common;
+}
+
+static int fsg_common_init(struct fsg_common *common,
+			   struct usb_composite_dev *cdev)
+{
+	struct usb_gadget *gadget = cdev->gadget;
+	struct file_list_entry *fentry;
+	struct fsg_buffhd *bh;
+	int nluns, i, fd = -1, rc;
+
+	ums_count = 0;
+
+	common->gadget = gadget;
+	common->ep0 = gadget->ep0;
+	common->ep0req = cdev->req;
+
+	thread_task = bthread_run(fsg_main_thread, common, "file-storage");
+	if (IS_ERR(thread_task))
+		return PTR_ERR(thread_task);
+
+	file_list_detect_all(ums_files);
+
+	file_list_for_each_entry(ums_files, fentry) {
+		unsigned flags = O_RDWR;
+		struct stat st;
+
+		if (fentry->flags) {
+			pr_err("flags not supported\n");
+			return -ENOSYS;
+		}
+
+		fd = open(fentry->filename, flags);
+		if (fd < 0) {
+			pr_err("open('%s') failed: %pe\n",
+			       fentry->filename, ERR_PTR(fd));
+			return fd;
+		}
+
+		rc = fstat(fd, &st);
+		if (rc < 0) {
+			pr_err("stat('%s') failed: %pe\n",
+			       fentry->filename, ERR_PTR(rc));
+			goto close;
+		}
+
+		if (st.st_size % SECTOR_SIZE != 0) {
+			pr_err("exporting '%s' failed: invalid block size\n",
+			       fentry->filename);
+			goto close;
+		}
+
+		ums[ums_count].fd = fd;
+		ums[ums_count].num_sectors = st.st_size / SECTOR_SIZE;
+
+		strlcpy(ums[ums_count].name, fentry->name, sizeof(ums[ums_count].name));
+
+		DBG(common, "LUN %d, %s sector_count %#x\n",
+			ums_count, fentry->name, ums[ums_count].num_sectors);
+
+		ums_count++;
+	}
+
+	/* Find out how many LUNs there should be */
+	nluns = ums_count;
+	if (nluns < 1 || nluns > FSG_MAX_LUNS) {
+		pr_warn("invalid number of LUNs: %u\n", nluns);
+		rc = -EINVAL;
+		goto close;
+	}
+
+	/* Maybe allocate device-global string IDs, and patch descriptors */
+	if (fsg_strings[FSG_STRING_INTERFACE].id == 0) {
+		rc = usb_string_id(cdev);
+		if (unlikely(rc < 0))
+			goto error_release;
+		fsg_strings[FSG_STRING_INTERFACE].id = rc;
+		fsg_intf_desc.iInterface = rc;
+	}
+
+	common->nluns = nluns;
+
+	for (i = 0; i < nluns; i++) {
+		common->luns[i].removable = 1;
+
+		rc = fsg_lun_open(&common->luns[i], ums[i].num_sectors, "");
+		if (rc)
+			goto error_luns;
+	}
+	common->lun = 0;
+
+	/* Data buffers cyclic list */
+	bh = common->buffhds;
+
+	i = FSG_NUM_BUFFERS;
+	goto buffhds_first_it;
+	do {
+		bh->next = bh + 1;
+		++bh;
+buffhds_first_it:
+		bh->inreq_busy = 0;
+		bh->outreq_busy = 0;
+		bh->buf = dma_alloc(FSG_BUFLEN);
+		if (unlikely(!bh->buf)) {
+			rc = -ENOMEM;
+			goto error_release;
+		}
+	} while (--i);
+	bh->next = common->buffhds;
+
+	snprintf(common->inquiry_string, sizeof common->inquiry_string,
+		 "%-8s%-16s%04x",
+		 "Linux   ",
+		 "File-Store Gadget",
+		 0xffff);
+
+	/* Some peripheral controllers are known not to be able to
+	 * halt bulk endpoints correctly.  If one of them is present,
+	 * disable stalls.
+	 */
+
+	/* Information */
+	DBG(common, FSG_DRIVER_DESC ", version: " FSG_DRIVER_VERSION "\n");
+	DBG(common, "Number of LUNs=%d\n", common->nluns);
+
+	return 0;
+
+error_luns:
+	common->nluns = i + 1;
+error_release:
+	common->state = FSG_STATE_TERMINATED;	/* The thread is dead */
+	fsg_common_release(common);
+close:
+	close(fd);
+	return rc;
+}
+
+static void fsg_common_release(struct fsg_common *common)
+{
+	struct fsg_buffhd *bh;
+	unsigned i;
+
+	/* If the thread isn't already dead, tell it to exit now */
+	if (common->state != FSG_STATE_TERMINATED) {
+		raise_exception(common, FSG_STATE_EXIT);
+		bthread_stop(thread_task);
+		bthread_free(thread_task);
+	}
+
+	bh = common->buffhds;
+	i = FSG_NUM_BUFFERS;
+
+	do {
+		dma_free(bh->buf);
+	} while (++bh, --i);
+
+	ums_count = 0;
+}
+
+
+static void fsg_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct fsg_dev		*fsg = fsg_from_func(f);
+	struct fsg_common	*common = fsg->common;
+	int i;
+
+	DBG(fsg, "unbind\n");
+
+	if (fsg->common->fsg == fsg) {
+		fsg->common->new_fsg = NULL;
+		raise_exception(fsg->common, FSG_STATE_CONFIG_CHANGE);
+
+		bthread_stop(thread_task);
+		while (common->fsg == fsg)
+			bthread_reschedule();
+	}
+
+	usb_free_all_descriptors(&fsg->function);
+
+	for (i = 0; i < ums_count; i++)
+		close(ums[i].fd);
+
+	fsg_common_release(fsg->common);
+
+	ums_files = NULL;
+}
+
+static int fsg_bind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct fsg_dev		*fsg = fsg_from_func(f);
+	struct usb_gadget	*gadget = c->cdev->gadget;
+	int			ret;
+	struct usb_ep		*ep;
+	struct usb_descriptor_header **hs_function = NULL;
+	struct fsg_common	*common = fsg->common;
+
+	if (!ums_files) {
+		struct f_ums_opts *opts = container_of(f->fi, struct f_ums_opts, func_inst);
+
+		ums_files = opts->files;
+	}
+
+	fsg->gadget = gadget;
+
+	DBG(fsg, "bind\n");
+
+	ret = fsg_common_init(common, c->cdev);
+	if (ret)
+		goto remove_ums_files;
+
+	/* New interface */
+	ret = usb_interface_id(c, f);
+	if (ret < 0)
+		goto fsg_common_release;
+	fsg_intf_desc.bInterfaceNumber = ret;
+	fsg->interface_number = ret;
+
+	ret = -EOPNOTSUPP;
+
+	/* Find all the endpoints we will use */
+	ep = usb_ep_autoconfig(gadget, &fsg_fs_bulk_in_desc);
+	if (!ep)
+		goto autoconf_fail;
+
+	ep->driver_data = common;	/* claim the endpoint */
+	fsg->bulk_in = ep;
+
+	ep = usb_ep_autoconfig(gadget, &fsg_fs_bulk_out_desc);
+	if (!ep)
+		goto autoconf_fail;
+
+	ep->driver_data = common;	/* claim the endpoint */
+	fsg->bulk_out = ep;
+
+	if (gadget_is_dualspeed(gadget)) {
+		/* Assume endpoint addresses are the same for both speeds */
+		fsg_hs_bulk_in_desc.bEndpointAddress =
+			fsg_fs_bulk_in_desc.bEndpointAddress;
+		fsg_hs_bulk_out_desc.bEndpointAddress =
+			fsg_fs_bulk_out_desc.bEndpointAddress;
+		hs_function = fsg_hs_function;
+	}
+
+	/* Copy descriptors */
+	return usb_assign_descriptors(f, fsg_fs_function, hs_function, NULL);
+
+autoconf_fail:
+	ERROR(fsg, "unable to autoconfigure all endpoints\n");
+fsg_common_release:
+	fsg_common_release(common);
+remove_ums_files:
+	ums_files = NULL;
+
+	return ret;
+}
+
+
+/****************************** ADD FUNCTION ******************************/
+
+static struct usb_gadget_strings *fsg_strings_array[] = {
+	&fsg_stringtab,
+	NULL,
+};
+
+static void fsg_free(struct usb_function *f)
+{
+	struct fsg_dev *fsg;
+
+	fsg = container_of(f, struct fsg_dev, function);
+
+	kfree(fsg);
+}
+
+static struct usb_function *fsg_alloc(struct usb_function_instance *fi)
+{
+	struct f_ums_opts *opts = fsg_opts_from_func_inst(fi);
+	struct fsg_common *common = opts->common;
+	struct fsg_dev *fsg;
+
+	fsg = kzalloc(sizeof(*fsg), GFP_KERNEL);
+	if (!fsg)
+		return ERR_PTR(-ENOMEM);
+
+	fsg->function.name = FSG_DRIVER_DESC;
+	fsg->function.strings = fsg_strings_array;
+	/* descriptors are per-instance copies */
+	fsg->function.bind = fsg_bind;
+	fsg->function.set_alt = fsg_set_alt;
+	fsg->function.setup = fsg_setup;
+	fsg->function.disable = fsg_disable;
+	fsg->function.unbind = fsg_unbind;
+	fsg->function.free_func = fsg_free;
+
+	fsg->common = common;
+	common->fsg = fsg;
+
+	return &fsg->function;
+}
+
+static void fsg_free_instance(struct usb_function_instance *fi)
+{
+	struct f_ums_opts *opts = fsg_opts_from_func_inst(fi);
+
+	kfree(opts->common);
+	kfree(opts);
+}
+
+static struct usb_function_instance *fsg_alloc_inst(void)
+{
+	struct f_ums_opts *opts;
+
+	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
+	if (!opts)
+		return ERR_PTR(-ENOMEM);
+
+	opts->func_inst.free_func_inst = fsg_free_instance;
+
+	opts->common = fsg_common_setup();
+	if (!opts->common) {
+		free(opts);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	return &opts->func_inst;
+}
+
+DECLARE_USB_FUNCTION_INIT(ums, fsg_alloc_inst, fsg_alloc);
diff --git a/drivers/usb/gadget/multi.c b/drivers/usb/gadget/multi.c
index 144ac0624be2..04b3c2604ef3 100644
--- a/drivers/usb/gadget/multi.c
+++ b/drivers/usb/gadget/multi.c
@@ -60,6 +60,8 @@ static struct usb_function_instance *fi_dfu;
 static struct usb_function *f_dfu;
 static struct usb_function_instance *fi_fastboot;
 static struct usb_function *f_fastboot;
+static struct usb_function_instance *fi_ums;
+static struct usb_function *f_ums;
 
 static struct usb_configuration config = {
 	.bConfigurationValue	= 1,
@@ -139,6 +141,31 @@ static int multi_bind_fastboot(struct usb_composite_dev *cdev)
 	return usb_add_function(&config, f_fastboot);
 }
 
+static int multi_bind_ums(struct usb_composite_dev *cdev)
+{
+	int ret;
+	struct f_ums_opts *opts;
+
+	fi_ums = usb_get_function_instance("ums");
+	if (IS_ERR(fi_ums)) {
+		ret = PTR_ERR(fi_ums);
+		fi_ums = NULL;
+		return ret;
+	}
+
+	opts = container_of(fi_ums, struct f_ums_opts, func_inst);
+	opts->files = gadget_multi_opts->ums_opts.files;
+
+	f_ums = usb_get_function(fi_ums);
+	if (IS_ERR(f_ums)) {
+		ret = PTR_ERR(f_ums);
+		f_ums = NULL;
+		return ret;
+	}
+
+	return usb_add_function(&config, f_ums);
+}
+
 static int multi_unbind(struct usb_composite_dev *cdev)
 {
 	if (gadget_multi_opts->create_acm) {
@@ -205,6 +232,13 @@ static int multi_bind(struct usb_composite_dev *cdev)
 			goto out;
 	}
 
+	if (gadget_multi_opts->ums_opts.files) {
+		printf("%s: creating USB Mass Storage function\n", __func__);
+		ret = multi_bind_ums(cdev);
+		if (ret)
+			goto out;
+	}
+
 	if (gadget_multi_opts->create_acm) {
 		printf("%s: creating ACM function\n", __func__);
 		ret = multi_bind_acm(cdev);
@@ -273,6 +307,7 @@ unsigned usb_multi_count_functions(struct f_multi_opts *opts)
 	count += !file_list_empty(opts->fastboot_opts.files) ||
 		opts->fastboot_opts.export_bbu;
 	count += !file_list_empty(opts->dfu_opts.files);
+	count += !file_list_empty(opts->ums_opts.files);
 	count += opts->create_acm;
 
 	return count;
@@ -282,6 +317,7 @@ void usb_multi_opts_release(struct f_multi_opts *opts)
 {
 	file_list_free(opts->fastboot_opts.files);
 	file_list_free(opts->dfu_opts.files);
+	file_list_free(opts->ums_opts.files);
 
 	free(opts);
 }
diff --git a/drivers/usb/gadget/storage_common.c b/drivers/usb/gadget/storage_common.c
new file mode 100644
index 000000000000..88cd745063e4
--- /dev/null
+++ b/drivers/usb/gadget/storage_common.c
@@ -0,0 +1,173 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * storage_common.c -- Common definitions for mass storage functionality
+ *
+ * Copyright (C) 2003-2008 Alan Stern
+ * Copyeight (C) 2009 Samsung Electronics
+ * Author: Michal Nazarewicz (m.nazarewicz@samsung.com)
+ *
+ * Ported to u-boot:
+ * Andrzej Pietrasiewicz <andrzej.p@samsung.com>
+ *
+ * Code refactoring & cleanup:
+ * Łukasz Majewski <l.majewski@samsung.com>
+ */
+
+#include "storage_common.h"
+
+/*
+ * This file requires the following identifiers used in USB strings to
+ * be defined (each of type pointer to char):
+ *  - fsg_string_manufacturer -- name of the manufacturer
+ *  - fsg_string_product      -- name of the product
+ *  - fsg_string_serial       -- product's serial
+ *  - fsg_string_config       -- name of the configuration
+ *  - fsg_string_interface    -- name of the interface
+ * The first four are only needed when FSG_DESCRIPTORS_DEVICE_STRINGS
+ * macro is defined prior to including this file.
+ */
+
+/* There is only one interface. */
+
+struct usb_interface_descriptor fsg_intf_desc = {
+	.bLength =		sizeof fsg_intf_desc,
+	.bDescriptorType =	USB_DT_INTERFACE,
+
+	.bNumEndpoints =	2,		/* Adjusted during fsg_bind() */
+	.bInterfaceClass =	USB_CLASS_MASS_STORAGE,
+	.bInterfaceSubClass =	USB_SC_SCSI,	/* Adjusted during fsg_bind() */
+	.bInterfaceProtocol =	USB_PR_BULK,	/* Adjusted during fsg_bind() */
+	.iInterface =		FSG_STRING_INTERFACE,
+};
+
+/*
+ * Three full-speed endpoint descriptors: bulk-in, bulk-out, and
+ * interrupt-in.
+ */
+
+struct usb_endpoint_descriptor fsg_fs_bulk_in_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	/* wMaxPacketSize set by autoconfiguration */
+};
+
+struct usb_endpoint_descriptor fsg_fs_bulk_out_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	/* wMaxPacketSize set by autoconfiguration */
+};
+
+struct usb_descriptor_header *fsg_fs_function[] = {
+	(struct usb_descriptor_header *) &fsg_intf_desc,
+	(struct usb_descriptor_header *) &fsg_fs_bulk_in_desc,
+	(struct usb_descriptor_header *) &fsg_fs_bulk_out_desc,
+	NULL,
+};
+
+/*
+ * USB 2.0 devices need to expose both high speed and full speed
+ * descriptors, unless they only run at full speed.
+ *
+ * That means alternate endpoint descriptors (bigger packets)
+ * and a "device qualifier" ... plus more construction options
+ * for the configuration descriptor.
+ */
+struct usb_endpoint_descriptor fsg_hs_bulk_in_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	/* bEndpointAddress copied from fs_bulk_in_desc during fsg_bind() */
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(512),
+};
+
+struct usb_endpoint_descriptor fsg_hs_bulk_out_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	/* bEndpointAddress copied from fs_bulk_out_desc during fsg_bind() */
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(512),
+	.bInterval =		1,	/* NAK every 1 uframe */
+};
+
+struct usb_descriptor_header *fsg_hs_function[] = {
+	(struct usb_descriptor_header *) &fsg_intf_desc,
+	(struct usb_descriptor_header *) &fsg_hs_bulk_in_desc,
+	(struct usb_descriptor_header *) &fsg_hs_bulk_out_desc,
+	NULL,
+};
+
+/* Maxpacket and other transfer characteristics vary by speed. */
+struct usb_endpoint_descriptor *
+fsg_ep_desc(struct usb_gadget *g, struct usb_endpoint_descriptor *fs,
+		struct usb_endpoint_descriptor *hs)
+{
+	if (gadget_is_dualspeed(g) && g->speed == USB_SPEED_HIGH)
+		return hs;
+	return fs;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * If the next two routines are called while the gadget is registered,
+ * the caller must own fsg->filesem for writing.
+ */
+
+int fsg_lun_open(struct fsg_lun *curlun, unsigned int num_sectors,
+		 const char *filename)
+{
+	int				ro;
+
+	/* R/W if we can, R/O if we must */
+	ro = curlun->initially_ro;
+
+	curlun->ro = ro;
+	curlun->file_length = num_sectors << 9;
+	curlun->num_sectors = num_sectors;
+	debug("open backing file: %s\n", filename);
+
+	return 0;
+}
+
+void fsg_lun_close(struct fsg_lun *curlun)
+{
+}
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * Sync the file data, don't bother with the metadata.
+ * This code was copied from fs/buffer.c:sys_fdatasync().
+ */
+int fsg_lun_fsync_sub(struct fsg_lun *curlun)
+{
+	return 0;
+}
+
+void store_cdrom_address(u8 *dest, int msf, u32 addr)
+{
+	if (msf) {
+		/* Convert to Minutes-Seconds-Frames */
+		addr >>= 2;		/* Convert to 2048-byte frames */
+		addr += 2*75;		/* Lead-in occupies 2 seconds */
+		dest[3] = addr % 75;	/* Frames */
+		addr /= 75;
+		dest[2] = addr % 60;	/* Seconds */
+		addr /= 60;
+		dest[1] = addr;		/* Minutes */
+		dest[0] = 0;		/* Reserved */
+	} else {
+		/* Absolute sector */
+		put_unaligned_be32(addr, dest);
+	}
+}
+
+/*-------------------------------------------------------------------------*/
diff --git a/drivers/usb/gadget/storage_common.h b/drivers/usb/gadget/storage_common.h
new file mode 100644
index 000000000000..ce07a7dac72c
--- /dev/null
+++ b/drivers/usb/gadget/storage_common.h
@@ -0,0 +1,245 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef USB_STORAGE_COMMON_H
+#define USB_STORAGE_COMMON_H
+
+#include <driver.h>
+#include <usb/storage.h>
+#include <asm/unaligned.h>
+#include <usb/mass_storage.h>
+
+#ifndef DEBUG
+#undef VERBOSE_DEBUG
+#undef DUMP_MSGS
+#endif /* !DEBUG */
+
+#define VLDBG(lun, fmt, args...)  dev_vdbg(&(lun)->dev, fmt, ## args)
+#define LDBG(lun, fmt, args...)   dev_dbg (&(lun)->dev, fmt, ## args)
+#define LERROR(lun, fmt, args...) dev_err (&(lun)->dev, fmt, ## args)
+#define LWARN(lun, fmt, args...)  dev_warn(&(lun)->dev, fmt, ## args)
+#define LINFO(lun, fmt, args...)  dev_info(&(lun)->dev, fmt, ## args)
+
+/*
+ * Keep those macros in sync with those in
+ * include/linux/usb/composite.h or else GCC will complain.  If they
+ * are identical (the same names of arguments, white spaces in the
+ * same places) GCC will allow redefinition otherwise (even if some
+ * white space is removed or added) warning will be issued.
+ *
+ * Those macros are needed here because File Storage Gadget does not
+ * include the composite.h header.  For composite gadgets those macros
+ * are redundant since composite.h is included any way.
+ *
+ * One could check whether those macros are already defined (which
+ * would indicate composite.h had been included) or not (which would
+ * indicate we were in FSG) but this is not done because a warning is
+ * desired if definitions here differ from the ones in composite.h.
+ *
+ * We want the definitions to match and be the same in File Storage
+ * Gadget as well as Mass Storage Function (and so composite gadgets
+ * using MSF).  If someone changes them in composite.h it will produce
+ * a warning in this file when building MSF.
+ */
+
+#define DBG(d, fmt, args...) \
+	dev_dbg(&(d)->gadget->dev , fmt , ## args)
+#define VDBG(d, fmt, args...) \
+	dev_vdbg(&(d)->gadget->dev , fmt , ## args)
+#define ERROR(d, fmt, args...) \
+	dev_err(&(d)->gadget->dev , fmt , ## args)
+#define WARNING(d, fmt, args...) \
+	dev_warn(&(d)->gadget->dev , fmt , ## args)
+#define INFO(d, fmt, args...) \
+	dev_info(&(d)->gadget->dev , fmt , ## args)
+
+#ifdef DUMP_MSGS
+
+/* dump_msg(fsg, const char * label, const u8 * buf, unsigned length); */
+# define dump_msg(fsg, label, buf, length) do {                         \
+	if (length < 512) {						\
+		DBG(fsg, "%s, length %u:\n", label, length);		\
+		print_hex_dump("", DUMP_PREFIX_OFFSET,	\
+			       16, 1, buf, length, 0);			\
+	}								\
+} while (0)
+
+#  define dump_cdb(fsg) do { } while (0)
+
+#else
+
+#  define dump_msg(fsg, /* const char * */ label, \
+		   /* const u8 * */ buf, /* unsigned */ length) do { } while (0)
+
+#  ifdef VERBOSE_DEBUG
+
+#    define dump_cdb(fsg)						\
+	print_hex_dump("SCSI CDB: ", DUMP_PREFIX_NONE,	\
+		       16, 1, (fsg)->cmnd, (fsg)->cmnd_size, 0)		\
+
+#  else
+
+#    define dump_cdb(fsg) do { } while (0)
+
+#  endif /* VERBOSE_DEBUG */
+
+#endif /* DUMP_MSGS */
+
+/*
+ * Thanks to NetChip Technologies for donating this product ID.
+ *
+ * DO NOT REUSE THESE IDs with any other driver!!  Ever!!
+ * Instead:  allocate your own, using normal USB-IF procedures.
+ */
+
+#define FSG_VENDOR_ID	0x0525	/* NetChip */
+#define FSG_PRODUCT_ID	0xa4a5	/* Linux-USB File-backed Storage Gadget */
+
+/* Length of a SCSI Command Data Block */
+#define MAX_COMMAND_SIZE	16
+
+/* SCSI Sense Key/Additional Sense Code/ASC Qualifier values */
+#define SS_NO_SENSE				0
+#define SS_COMMUNICATION_FAILURE		0x040800
+#define SS_INVALID_COMMAND			0x052000
+#define SS_INVALID_FIELD_IN_CDB			0x052400
+#define SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE	0x052100
+#define SS_LOGICAL_UNIT_NOT_SUPPORTED		0x052500
+#define SS_MEDIUM_NOT_PRESENT			0x023a00
+#define SS_MEDIUM_REMOVAL_PREVENTED		0x055302
+#define SS_NOT_READY_TO_READY_TRANSITION	0x062800
+#define SS_RESET_OCCURRED			0x062900
+#define SS_SAVING_PARAMETERS_NOT_SUPPORTED	0x053900
+#define SS_UNRECOVERED_READ_ERROR		0x031100
+#define SS_WRITE_ERROR				0x030c02
+#define SS_WRITE_PROTECTED			0x072700
+
+#define SK(x)		((u8) ((x) >> 16))	/* Sense Key byte, etc. */
+#define ASC(x)		((u8) ((x) >> 8))
+#define ASCQ(x)		((u8) (x))
+
+/*-------------------------------------------------------------------------*/
+
+struct fsg_lun {
+	loff_t		file_length;
+	loff_t		num_sectors;
+
+	unsigned int	initially_ro:1;
+	unsigned int	ro:1;
+	unsigned int	removable:1;
+	unsigned int	cdrom:1;
+	unsigned int	prevent_medium_removal:1;
+	unsigned int	registered:1;
+	unsigned int	info_valid:1;
+	unsigned int	nofua:1;
+
+	u32		sense_data;
+	u32		sense_data_info;
+	u32		unit_attention_data;
+
+	struct device_d	dev;
+};
+
+#define fsg_lun_is_open(curlun)	((curlun)->filp != NULL)
+
+/* Big enough to hold our biggest descriptor */
+#define EP0_BUFSIZE	256
+#define DELAYED_STATUS	(EP0_BUFSIZE + 999)	/* An impossibly large value */
+
+/* Number of buffers we will use.  2 is enough for double-buffering */
+#define FSG_NUM_BUFFERS	2
+
+/* Default size of buffer length. */
+#define FSG_BUFLEN	((u32)131072)
+
+/* Maximal number of LUNs supported in mass storage function */
+#define FSG_MAX_LUNS	8
+
+enum fsg_buffer_state {
+	BUF_STATE_EMPTY = 0,
+	BUF_STATE_FULL,
+	BUF_STATE_BUSY
+};
+
+/*
+ * When FSG_BUFFHD_STATIC_BUFFER is defined when this file is included
+ * the fsg_buffhd structure's buf field will be an array of FSG_BUFLEN
+ * characters rather then a pointer to void.
+ */
+
+struct fsg_buffhd {
+	void				*buf;
+	enum fsg_buffer_state		state;
+	struct fsg_buffhd		*next;
+
+	/*
+	 * The NetChip 2280 is faster, and handles some protocol faults
+	 * better, if we don't submit any short bulk-out read requests.
+	 * So we will record the intended request length here.
+	 */
+	unsigned int			bulk_out_intended_length;
+
+	struct usb_request		*inreq;
+	int				inreq_busy;
+	struct usb_request		*outreq;
+	int				outreq_busy;
+};
+
+enum fsg_state {
+	/* This one isn't used anywhere */
+	FSG_STATE_COMMAND_PHASE = -10,
+	FSG_STATE_DATA_PHASE,
+	FSG_STATE_STATUS_PHASE,
+
+	FSG_STATE_IDLE = 0,
+	FSG_STATE_ABORT_BULK_OUT,
+	FSG_STATE_RESET,
+	FSG_STATE_INTERFACE_CHANGE,
+	FSG_STATE_CONFIG_CHANGE,
+	FSG_STATE_DISCONNECT,
+	FSG_STATE_EXIT,
+	FSG_STATE_TERMINATED
+};
+
+enum data_direction {
+	DATA_DIR_UNKNOWN = 0,
+	DATA_DIR_FROM_HOST,
+	DATA_DIR_TO_HOST,
+	DATA_DIR_NONE
+};
+
+/*-------------------------------------------------------------------------*/
+
+static inline u32 get_unaligned_be24(u8 *buf)
+{
+	return 0xffffff & (u32) get_unaligned_be32(buf - 1);
+}
+
+/*-------------------------------------------------------------------------*/
+
+enum {
+	FSG_STRING_INTERFACE
+};
+
+/*-------------------------------------------------------------------------*/
+
+extern struct usb_interface_descriptor fsg_intf_desc;
+
+extern struct usb_endpoint_descriptor fsg_fs_bulk_in_desc;
+extern struct usb_endpoint_descriptor fsg_fs_bulk_out_desc;
+extern struct usb_descriptor_header *fsg_fs_function[];
+
+extern struct usb_endpoint_descriptor fsg_hs_bulk_in_desc;
+extern struct usb_endpoint_descriptor fsg_hs_bulk_out_desc;
+extern struct usb_descriptor_header *fsg_hs_function[];
+
+int fsg_lun_open(struct fsg_lun *curlun, unsigned int num_sectors,
+		 const char *filename);
+void fsg_lun_close(struct fsg_lun *curlun);
+
+struct usb_endpoint_descriptor *
+fsg_ep_desc(struct usb_gadget *g, struct usb_endpoint_descriptor *fs,
+		struct usb_endpoint_descriptor *hs);
+int fsg_lun_fsync_sub(struct fsg_lun *curlun);
+void store_cdrom_address(u8 *dest, int msf, u32 addr);
+
+#endif /* USB_STORAGE_COMMON_H */
diff --git a/include/scsi.h b/include/scsi.h
index f84513b813e9..23fc7abbaf42 100644
--- a/include/scsi.h
+++ b/include/scsi.h
@@ -109,12 +109,15 @@
 #define SCSI_MED_REMOVL	0x1E		/* Prevent/Allow medium Removal (O) */
 #define SCSI_READ6	0x08		/* Read 6-byte (MANDATORY) */
 #define SCSI_READ10	0x28		/* Read 10-byte (MANDATORY) */
+#define SCSI_READ12	0xA8		/* Read 12-byte (O) */
 #define SCSI_READ16	0x88		/* Read 16-byte (O) */
 #define SCSI_RD_CAPAC	0x25		/* Read Capacity (MANDATORY) */
+#define SCSI_RD_FMT_CAPAC	0x23
 #define SCSI_RD_DEFECT	0x37		/* Read Defect Data (O) */
 #define SCSI_READ_LONG	0x3E		/* Read Long (O) */
 #define SCSI_REASS_BLK	0x07		/* Reassign Blocks (O) */
 #define SCSI_RCV_DIAG	0x1C		/* Receive Diagnostic Results (O) */
+#define SCSI_RESERVE	0x16
 #define SCSI_RELEASE	0x17		/* Release Unit (MANDATORY) */
 #define SCSI_REZERO	0x01		/* Rezero Unit (O) */
 #define SCSI_SRCH_DAT_E	0x31		/* Search Data Equal (O) */
@@ -129,10 +132,13 @@
 #define SCSI_VERIFY	0x2F		/* Verify (O) */
 #define SCSI_WRITE6	0x0A		/* Write 6-Byte (MANDATORY) */
 #define SCSI_WRITE10	0x2A		/* Write 10-Byte (MANDATORY) */
+#define SCSI_WRITE12	0xAA		/* Write 12-Byte (O) */
 #define SCSI_WRITE16	0x8A		/* Write 16-Byte (O) */
 #define SCSI_WRT_VERIFY	0x2E		/* Write and Verify (O) */
 #define SCSI_WRITE_LONG	0x3F		/* Write Long (O) */
 #define SCSI_WRITE_SAME	0x41		/* Write Same (O) */
+#define SCSI_RD_TOC	0x43
+#define SCSI_RD_HEADER	0x44
 
 #define SERVICE_ACTION_IN_16	0x9e
 /* values for service action in */
@@ -170,4 +176,10 @@ void scsi_init(void);
 #define FALSE 0
 #endif
 
+/*
+ *  DEVICE TYPES
+ */
+
+#define TYPE_DISK           0x00
+
 #endif /* _SCSI_H */
diff --git a/include/usb/gadget-multi.h b/include/usb/gadget-multi.h
index 482aee11d047..79b24ca4df72 100644
--- a/include/usb/gadget-multi.h
+++ b/include/usb/gadget-multi.h
@@ -4,10 +4,12 @@
 #include <usb/fastboot.h>
 #include <usb/dfu.h>
 #include <usb/usbserial.h>
+#include <usb/mass_storage.h>
 
 struct f_multi_opts {
 	struct fastboot_opts fastboot_opts;
 	struct f_dfu_opts dfu_opts;
+	struct f_ums_opts ums_opts;
 	bool create_acm;
 	void (*release)(struct f_multi_opts *opts);
 };
@@ -21,11 +23,13 @@ unsigned usb_multi_count_functions(struct f_multi_opts *opts);
 #define USBGADGET_ACM		(1 << 1)
 #define USBGADGET_DFU		(1 << 2)
 #define USBGADGET_FASTBOOT	(1 << 3)
+#define USBGADGET_MASS_STORAGE	(1 << 4)
 
 struct usbgadget_funcs {
 	int flags;
 	const char *fastboot_opts;
 	const char *dfu_opts;
+	const char *ums_opts;
 };
 
 int usbgadget_register(const struct usbgadget_funcs *funcs);
diff --git a/include/usb/mass_storage.h b/include/usb/mass_storage.h
new file mode 100644
index 000000000000..084b3c8e8f31
--- /dev/null
+++ b/include/usb/mass_storage.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) 2011 Samsung Electrnoics
+ * Lukasz Majewski <l.majewski@samsung.com>
+ */
+
+#ifndef __USB_MASS_STORAGE_H__
+#define __USB_MASS_STORAGE_H__
+
+#include <usb/composite.h>
+
+/* Wait at maximum 60 seconds for cable connection */
+#define UMS_CABLE_READY_TIMEOUT	60
+
+struct fsg_common;
+
+struct f_ums_opts {
+	struct usb_function_instance func_inst;
+	struct fsg_common *common;
+	struct file_list *files;
+	unsigned int num_sectors;
+	int fd;
+	char name[16];
+};
+
+int usb_ums_register(struct f_ums_opts *);
+
+#endif /* __USB_MASS_STORAGE_H__ */
diff --git a/include/usb/storage.h b/include/usb/storage.h
new file mode 100644
index 000000000000..e0240f864548
--- /dev/null
+++ b/include/usb/storage.h
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef __LINUX_USB_STORAGE_H
+#define __LINUX_USB_STORAGE_H
+
+/*
+ * linux/usb/storage.h
+ *
+ * Copyright Matthew Wilcox for Intel Corp, 2010
+ *
+ * This file contains definitions taken from the
+ * USB Mass Storage Class Specification Overview
+ *
+ * Distributed under the terms of the GNU GPL, version two.
+ */
+
+/* Storage subclass codes */
+
+#define USB_SC_RBC	0x01		/* Typically, flash devices */
+#define USB_SC_8020	0x02		/* CD-ROM */
+#define USB_SC_QIC	0x03		/* QIC-157 Tapes */
+#define USB_SC_UFI	0x04		/* Floppy */
+#define USB_SC_8070	0x05		/* Removable media */
+#define USB_SC_SCSI	0x06		/* Transparent */
+#define USB_SC_LOCKABLE	0x07		/* Password-protected */
+
+#define USB_SC_ISD200	0xf0		/* ISD200 ATA */
+#define USB_SC_CYP_ATACB	0xf1	/* Cypress ATACB */
+#define USB_SC_DEVICE	0xff		/* Use device's value */
+
+/* Storage protocol codes */
+
+#define USB_PR_CBI	0x00		/* Control/Bulk/Interrupt */
+#define USB_PR_CB	0x01		/* Control/Bulk w/o interrupt */
+#define USB_PR_BULK	0x50		/* bulk only */
+#define USB_PR_UAS	0x62		/* USB Attached SCSI */
+
+#define USB_PR_USBAT	0x80		/* SCM-ATAPI bridge */
+#define USB_PR_EUSB_SDDR09	0x81	/* SCM-SCSI bridge for SDDR-09 */
+#define USB_PR_SDDR55	0x82		/* SDDR-55 (made up) */
+#define USB_PR_DPCM_USB	0xf0		/* Combination CB/SDDR09 */
+#define USB_PR_FREECOM	0xf1		/* Freecom */
+#define USB_PR_DATAFAB	0xf2		/* Datafab chipsets */
+#define USB_PR_JUMPSHOT	0xf3		/* Lexar Jumpshot */
+#define USB_PR_ALAUDA	0xf4		/* Alauda chipsets */
+#define USB_PR_KARMA	0xf5		/* Rio Karma */
+
+#define USB_PR_DEVICE	0xff		/* Use device's value */
+
+/*
+ * Bulk only data structures
+ */
+
+/* command block wrapper */
+struct bulk_cb_wrap {
+	__le32	Signature;		/* contains 'USBC' */
+	__u32	Tag;			/* unique per command id */
+	__le32	DataTransferLength;	/* size of data */
+	__u8	Flags;			/* direction in bit 0 */
+	__u8	Lun;			/* LUN normally 0 */
+	__u8	Length;			/* length of the CDB */
+	__u8	CDB[16];		/* max command */
+};
+
+#define US_BULK_CB_WRAP_LEN	31
+#define US_BULK_CB_SIGN		0x43425355	/* spells out 'USBC' */
+#define US_BULK_FLAG_IN		(1 << 7)
+#define US_BULK_FLAG_OUT	0
+
+/* command status wrapper */
+struct bulk_cs_wrap {
+	__le32	Signature;	/* contains 'USBS' */
+	__u32	Tag;		/* same as original command */
+	__le32	Residue;	/* amount not transferred */
+	__u8	Status;		/* see below */
+};
+
+#define US_BULK_CS_WRAP_LEN	13
+#define US_BULK_CS_SIGN		0x53425355      /* spells out 'USBS' */
+#define US_BULK_STAT_OK		0
+#define US_BULK_STAT_FAIL	1
+#define US_BULK_STAT_PHASE	2
+
+/* bulk-only class specific requests */
+#define US_BULK_RESET_REQUEST   0xff
+#define US_BULK_GET_MAX_LUN     0xfe
+
+#endif
-- 
2.29.2


_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox

      parent reply	other threads:[~2021-05-03 12:48 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-03 12:45 [PATCH v3 0/4] " Ahmad Fatoum
2021-05-03 12:45 ` [PATCH v3 1/4] bthread: implement basic Linux-like completion API Ahmad Fatoum
2021-05-03 12:45 ` [PATCH v3 2/4] slice: reschedule bthreads doing File I/O in command context Ahmad Fatoum
2021-05-03 12:45 ` [PATCH v3 3/4] usbgadget: refactor usbgadget_register to accept array Ahmad Fatoum
2021-05-03 12:45 ` Ahmad Fatoum [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210503124508.856-5-a.fatoum@pengutronix.de \
    --to=a.fatoum@pengutronix.de \
    --cc=barebox@lists.infradead.org \
    --subject='Re: [PATCH v3 4/4] usbgadget: add support for USB mass storage gadget' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox