[PATCH v2 2/4] base: add class device support

[Sascha Hauer <s.hauer@pengutronix.de>]

This introduces the concept of class devices in barebox. Class devices
group together devices of the same type. Several subsystems like
watchdog and network devices have a struct device embedded in their
subsystem specific struct anyway, so we can use this as a class device.
As these class devices are collected on a list we can use this list to
iterate over all network/watchdog devices and thus free the subsystems
from the burden of keeping a list themselves.

There is a 'class' command added in this patch which can be used to show
all registered classes along with the devices registered for each class.

The classes known at compile time can be collected on a linker list
using the macro DEFINE_DEV_CLASS(). That way registering classes does
not need an additional initcall and also no care has to be taken that
this initcalls runs before the first user adds devices to a new class.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 commands/Kconfig                  |  6 +++++
 commands/Makefile                 |  1 +
 commands/class.c                  | 30 ++++++++++++++++++++++
 drivers/base/Makefile             |  1 +
 drivers/base/class.c              | 41 +++++++++++++++++++++++++++++++
 include/asm-generic/barebox.lds.h |  7 ++++++
 include/device.h                  | 21 ++++++++++++++++
 7 files changed, 107 insertions(+)
 create mode 100644 commands/class.c
 create mode 100644 drivers/base/class.c

diff --git a/commands/Kconfig b/commands/Kconfig
index 899673bfee..c9c4be67e0 100644
--- a/commands/Kconfig
+++ b/commands/Kconfig
@@ -68,6 +68,12 @@ config CMD_BOOTROM
 
 	  bootrom [-la]
 
+config CMD_CLASS
+	tristate
+	prompt "class"
+	help
+	  Show information about registered device classes
+
 config CMD_DEVINFO
 	tristate
 	default y
diff --git a/commands/Makefile b/commands/Makefile
index 30e1f8403e..f65187703f 100644
--- a/commands/Makefile
+++ b/commands/Makefile
@@ -115,6 +115,7 @@ obj-$(CONFIG_CMD_BAREBOX_UPDATE)+= barebox-update.o
 obj-$(CONFIG_CMD_MIITOOL)	+= miitool.o
 obj-$(CONFIG_CMD_DETECT)	+= detect.o
 obj-$(CONFIG_CMD_BOOT)		+= boot.o
+obj-$(CONFIG_CMD_CLASS)		+= class.o
 obj-$(CONFIG_CMD_DEVINFO)	+= devinfo.o
 obj-$(CONFIG_CMD_DEVUNBIND)	+= devunbind.o
 obj-$(CONFIG_CMD_DEVLOOKUP)	+= devlookup.o
diff --git a/commands/class.c b/commands/class.c
new file mode 100644
index 0000000000..f5d67b012f
--- /dev/null
+++ b/commands/class.c
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <common.h>
+#include <command.h>
+#include <complete.h>
+
+static int do_class(int argc, char *argv[])
+{
+	struct class *class;
+	struct device *dev;
+
+	class_for_each(class) {
+		printf("%s:\n", class->name);
+		class_for_each_device(class, dev) {
+			printf("    %s\n", dev_name(dev));
+		}
+	}
+
+	return 0;
+}
+
+BAREBOX_CMD_HELP_START(class)
+BAREBOX_CMD_HELP_TEXT("Show information about registered classes and their devices")
+BAREBOX_CMD_HELP_END
+
+BAREBOX_CMD_START(class)
+	.cmd = do_class,
+	BAREBOX_CMD_DESC("show information about classes")
+	BAREBOX_CMD_GROUP(CMD_GRP_INFO)
+	BAREBOX_CMD_COMPLETE(empty_complete)
+BAREBOX_CMD_END
diff --git a/drivers/base/Makefile b/drivers/base/Makefile
index acc53763da..94b677eea0 100644
--- a/drivers/base/Makefile
+++ b/drivers/base/Makefile
@@ -3,6 +3,7 @@ obj-y	+= bus.o
 obj-y	+= driver.o
 obj-y	+= platform.o
 obj-y	+= resource.o
+obj-y	+= class.o
 obj-y	+= regmap/
 
 obj-$(CONFIG_PM_GENERIC_DOMAINS) += power.o
diff --git a/drivers/base/class.c b/drivers/base/class.c
new file mode 100644
index 0000000000..6757d34140
--- /dev/null
+++ b/drivers/base/class.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <device.h>
+#include <driver.h>
+#include <linux/list.h>
+
+LIST_HEAD(class_list);
+
+static int class_register(struct class *class)
+{
+	list_add_tail(&class->list, &class_list);
+
+	return 0;
+}
+
+int class_add_device(struct class *class, struct device *dev)
+{
+	list_add_tail(&dev->class_list, &class->devices);
+
+	return 0;
+}
+
+void class_remove_device(struct class *class, struct device *dev)
+{
+	list_del(&class->devices);
+}
+
+extern struct class __barebox_class_start;
+extern struct class __barebox_class_end;
+
+static int register_classes(void)
+{
+	struct class *c;
+
+	for (c = &__barebox_class_start;
+	     c != &__barebox_class_end;
+	     c++)
+		class_register(c);
+
+	return 0;
+}
+device_initcall(register_classes);
diff --git a/include/asm-generic/barebox.lds.h b/include/asm-generic/barebox.lds.h
index d3736ebaed..8bbf5907cd 100644
--- a/include/asm-generic/barebox.lds.h
+++ b/include/asm-generic/barebox.lds.h
@@ -70,6 +70,12 @@
 	KEEP(*(SORT_BY_NAME(.barebox_magicvar*)))	\
 	__barebox_magicvar_end = .;
 
+#define BAREBOX_CLASSES				\
+	STRUCT_ALIGN();				\
+	__barebox_class_start = .;		\
+	KEEP(*(SORT_BY_NAME(.barebox_class*)))	\
+	__barebox_class_end = .;
+
 #define BAREBOX_CLK_TABLE			\
 	STRUCT_ALIGN();				\
 	__clk_of_table_start = .;		\
@@ -138,6 +144,7 @@
 	BAREBOX_SYMS				\
 	KERNEL_CTORS()				\
 	BAREBOX_MAGICVARS			\
+	BAREBOX_CLASSES				\
 	BAREBOX_CLK_TABLE			\
 	BAREBOX_DTB				\
 	BAREBOX_RSA_KEYS			\
diff --git a/include/device.h b/include/device.h
index ad1bc7ca1e..992ac7aa7b 100644
--- a/include/device.h
+++ b/include/device.h
@@ -76,6 +76,8 @@ struct device {
 
 	struct list_head cdevs;
 
+	struct list_head class_list;
+
 	const struct platform_device_id *id_entry;
 	union {
 		struct device_node *device_node;
@@ -102,6 +104,25 @@ struct device {
 	char *deferred_probe_reason;
 };
 
+struct class {
+	const char *name;
+	struct list_head devices;
+	struct list_head list;
+};
+
+#define DEFINE_DEV_CLASS(_name, _classname)					\
+	struct class _name __ll_elem(.barebox_class_##_name) = {		\
+		.name = _classname,						\
+		.devices = LIST_HEAD_INIT(_name.devices),			\
+	}
+
+int class_add_device(struct class *class, struct device *dev);
+void class_remove_device(struct class *class, struct device *dev);
+
+extern struct list_head class_list;
+#define class_for_each_device(class, dev) list_for_each_entry(dev, &class->devices, class_list)
+#define class_for_each(class) list_for_each_entry(class, &class_list, list)
+
 struct device_alias {
 	struct device *dev;
 	struct list_head list;
-- 
2.39.2