Re: [PATCH] nvmem: Port RAVE SP EEPROM driver from Linux kernel

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

On Mon, Jun 18, 2018 at 10:45:49PM -0700, Andrey Smirnov wrote:
> This is a minimal port of a kernel commit 3b51f47be171 ("nvmem: Add
> RAVE SP EEPROM driver"). All of the changes were kept to a minimum and
> limited to impedance matching between Barebox/Linux driver API.
> 
> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> ---

Applied, thanks

Sascha

>  drivers/nvmem/Kconfig          |   7 +
>  drivers/nvmem/Makefile         |   5 +-
>  drivers/nvmem/rave-sp-eeprom.c | 361 +++++++++++++++++++++++++++++++++
>  3 files changed, 372 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/nvmem/rave-sp-eeprom.c
> 
> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
> index a3797b4aa..38b6f4241 100644
> --- a/drivers/nvmem/Kconfig
> +++ b/drivers/nvmem/Kconfig
> @@ -36,4 +36,11 @@ config IMX_OCOTP_WRITE
>  	  the value of the address by 4.
>  	    mw -l -d /dev/imx-ocotp 0x8C 0x00001234
>  	    mw -l -d /dev/imx-ocotp 0x88 0x56789ABC
> +
> +config RAVE_SP_EEPROM
> +	tristate "Rave SP EEPROM Support"
> +	depends on RAVE_SP_CORE
> +	help
> +	  Say y here to enable Rave SP EEPROM support.
> +
>  endif
> diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
> index 998a9c4b9..716e5dbe8 100644
> --- a/drivers/nvmem/Makefile
> +++ b/drivers/nvmem/Makefile
> @@ -10,4 +10,7 @@ obj-$(CONFIG_NVMEM_SNVS_LPGPR)	+= nvmem_snvs_lpgpr.o
>  nvmem_snvs_lpgpr-y		:= snvs_lpgpr.o
>  
>  obj-$(CONFIG_IMX_OCOTP)		+= nvmem_ocotp.o
> -nvmem_ocotp-y			:= ocotp.o
> \ No newline at end of file
> +nvmem_ocotp-y			:= ocotp.o
> +
> +obj-$(CONFIG_RAVE_SP_EEPROM)	+= nvmem-rave-sp-eeprom.o
> +nvmem-rave-sp-eeprom-y		:= rave-sp-eeprom.o
> \ No newline at end of file
> diff --git a/drivers/nvmem/rave-sp-eeprom.c b/drivers/nvmem/rave-sp-eeprom.c
> new file mode 100644
> index 000000000..5fd429f16
> --- /dev/null
> +++ b/drivers/nvmem/rave-sp-eeprom.c
> @@ -0,0 +1,361 @@
> +/*
> + * EEPROM driver for RAVE SP
> + *
> + * Copyright (C) 2017 Zodiac Inflight Innovations
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation; either version 2 of
> + * the License, or (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <common.h>
> +#include <driver.h>
> +#include <init.h>
> +#include <io.h>
> +#include <of.h>
> +#include <of_device.h>
> +#include <malloc.h>
> +#include <linux/sizes.h>
> +#include <linux/mfd/rave-sp.h>
> +#include <linux/nvmem-provider.h>
> +
> +/**
> + * enum rave_sp_eeprom_access_type - Supported types of EEPROM access
> + *
> + * @RAVE_SP_EEPROM_WRITE:	EEPROM write
> + * @RAVE_SP_EEPROM_READ:	EEPROM read
> + *
> + * Note that values of both constant are chose so that they'd match
> + * similar values from RAVE SP ICD.
> + */
> +enum rave_sp_eeprom_access_type {
> +	RAVE_SP_EEPROM_WRITE = 0,
> +	RAVE_SP_EEPROM_READ  = 1,
> +};
> +
> +/**
> + * enum rave_sp_eeprom_header_size - EEPROM command header sizes
> + *
> + * @RAVE_SP_EEPROM_HEADER_SMALL:	EEPROM header size for "small" devices (< 8K)
> + * @RAVE_SP_EEPROM_HEADER_BIG:		EEPROM header size for "big" devices (> 8K, < 2M)
> + *
> + * Note that values of both constant are chose so that they'd match
> + * similar values from RAVE SP ICD.
> + */
> +enum rave_sp_eeprom_header_size {
> +	RAVE_SP_EEPROM_HEADER_SMALL = 4U,
> +	RAVE_SP_EEPROM_HEADER_BIG   = 5U,
> +};
> +
> +#define	RAVE_SP_EEPROM_PAGE_SIZE	32U
> +
> +/**
> + * struct rave_sp_eeprom_page - RAVE SP EEPROM page
> + *
> + * @type:	Access type (see enum rave_sp_eeprom_access_type)
> + * @success:	Success flag (Success = 1, Failure = 0)
> + * @data:	Read data
> + *
> + * Note that the layout of this structure is made to follow the layout
> + * of RSP_*_EEPROM from device's ICD (only the data portion of it due
> + * to how rave_sp_exec() returns data)
> + */
> +struct rave_sp_eeprom_page {
> +	u8  type;
> +	u8  success;
> +	u8  data[RAVE_SP_EEPROM_PAGE_SIZE];
> +} __packed;
> +
> +/**
> + * struct rave_sp_eeprom - RAVE SP EEPROM device
> + *
> + * @sp:			Pointer to parent RAVE SP device
> + * @mutex:		Lock protecting access to EEPROM
> + * @address:		EEPROM device address (first byte of the command to access it)
> + * @header_size:	Size of EEPROM command header for this device
> + */
> +struct rave_sp_eeprom {
> +	struct rave_sp *sp;
> +	u8 address;
> +	unsigned int header_size;
> +};
> +
> +/**
> + * rave_sp_eeprom_io - Low-level part of EEPROM page access
> + *
> + * @eeprom:	EEPROM device to write to
> + * @type:	EEPROM access type (read or write)
> + * @idx:	number of the EEPROM page
> + * @page:	Data to write or buffer to store result (via page->data)
> + *
> + * This function does all of the low-lever work required to perform a
> + * EEPROM access. This includes formatting corredct command payload,
> + * sending it and checking received results.
> + *
> + * Returns zero in case of success or negative error code in
> + * case of failure.
> + */
> +static int rave_sp_eeprom_io(struct rave_sp_eeprom *eeprom,
> +			     enum rave_sp_eeprom_access_type type,
> +			     u16 idx,
> +			     struct rave_sp_eeprom_page *page)
> +{
> +	const bool is_write = type == RAVE_SP_EEPROM_WRITE;
> +	const unsigned int data_size = is_write ? sizeof(page->data) : 0;
> +	const unsigned int cmd_size = eeprom->header_size + data_size;
> +	const unsigned int rsp_size =
> +		is_write ? sizeof(*page) - sizeof(page->data) : sizeof(*page);
> +	unsigned int offset = 0;
> +	u8 cmd[cmd_size];
> +	int ret;
> +
> +	cmd[offset++] = eeprom->address;
> +	cmd[offset++] = 0;
> +	cmd[offset++] = type;
> +	cmd[offset++] = idx;
> +
> +	if (offset < eeprom->header_size)
> +		cmd[offset++] = idx >> 8;
> +	/*
> +	 * Copy our data to write to command buffer first. In case of
> +	 * a read data_size should be zero and memcpy would become a
> +	 * no-op
> +	 */
> +	memcpy(&cmd[offset], page->data, data_size);
> +
> +	ret = rave_sp_exec(eeprom->sp, cmd, cmd_size, page, rsp_size);
> +	if (ret)
> +		return ret;
> +
> +	if (page->type != type)
> +		return -EPROTO;
> +
> +	if (!page->success)
> +		return -EIO;
> +
> +	return 0;
> +}
> +
> +/**
> + * rave_sp_eeprom_page_access - Access single EEPROM page
> + *
> + * @eeprom:	EEPROM device to access
> + * @type:	Access type to perform (read or write)
> + * @offset:	Offset within EEPROM to access
> + * @data:	Data buffer
> + * @data_len:	Size of the data buffer
> + *
> + * This function performs a generic access to a single page or a
> + * portion thereof. Requested access MUST NOT cross the EEPROM page
> + * boundary.
> + *
> + * Returns zero in case of success or negative error code in
> + * case of failure.
> + */
> +static int
> +rave_sp_eeprom_page_access(struct rave_sp_eeprom *eeprom,
> +			   enum rave_sp_eeprom_access_type type,
> +			   unsigned int offset, u8 *data,
> +			   size_t data_len)
> +{
> +	const unsigned int page_offset = offset % RAVE_SP_EEPROM_PAGE_SIZE;
> +	const unsigned int page_nr     = offset / RAVE_SP_EEPROM_PAGE_SIZE;
> +	struct rave_sp_eeprom_page page;
> +	int ret;
> +
> +	/*
> +	 * This function will not work if data access we've been asked
> +	 * to do is crossing EEPROM page boundary. Normally this
> +	 * should never happen and getting here would indicate a bug
> +	 * in the code.
> +	 */
> +	if (WARN_ON(data_len > sizeof(page.data) - page_offset))
> +		return -EINVAL;
> +
> +	if (type == RAVE_SP_EEPROM_WRITE) {
> +		/*
> +		 * If doing a partial write we need to do a read first
> +		 * to fill the rest of the page with correct data.
> +		 */
> +		if (data_len < RAVE_SP_EEPROM_PAGE_SIZE) {
> +			ret = rave_sp_eeprom_io(eeprom, RAVE_SP_EEPROM_READ,
> +						page_nr, &page);
> +			if (ret)
> +				return ret;
> +		}
> +
> +		memcpy(&page.data[page_offset], data, data_len);
> +	}
> +
> +	ret = rave_sp_eeprom_io(eeprom, type, page_nr, &page);
> +	if (ret)
> +		return ret;
> +
> +	/*
> +	 * Since we receive the result of the read via 'page.data'
> +	 * buffer we need to copy that to 'data'
> +	 */
> +	if (type == RAVE_SP_EEPROM_READ)
> +		memcpy(data, &page.data[page_offset], data_len);
> +
> +	return 0;
> +}
> +
> +/**
> + * rave_sp_eeprom_access - Access EEPROM data
> + *
> + * @eeprom:	EEPROM device to access
> + * @type:	Access type to perform (read or write)
> + * @offset:	Offset within EEPROM to access
> + * @data:	Data buffer
> + * @data_len:	Size of the data buffer
> + *
> + * This function performs a generic access (either read or write) at
> + * arbitrary offset (not necessary page aligned) of arbitrary length
> + * (is not constrained by EEPROM page size).
> + *
> + * Returns zero in case of success or negative error code in case of
> + * failure.
> + */
> +static int rave_sp_eeprom_access(struct rave_sp_eeprom *eeprom,
> +				 enum rave_sp_eeprom_access_type type,
> +				 unsigned int offset, u8 *data,
> +				 unsigned int data_len)
> +{
> +	unsigned int residue;
> +	unsigned int chunk;
> +	unsigned int head;
> +	int ret;
> +
> +	head    = offset % RAVE_SP_EEPROM_PAGE_SIZE;
> +	residue = data_len;
> +
> +	do {
> +		/*
> +		 * First iteration, if we are doing an access that is
> +		 * not 32-byte aligned, we need to access only data up
> +		 * to a page boundary to avoid corssing it in
> +		 * rave_sp_eeprom_page_access()
> +		 */
> +		if (head) {
> +			chunk = RAVE_SP_EEPROM_PAGE_SIZE - head;
> +			/*
> +			 * This can only happen once per
> +			 * rave_sp_eeprom_access() call, so we set
> +			 * head to zero to process all the other
> +			 * iterations normally.
> +			 */
> +			head  = 0;
> +		} else {
> +			chunk = RAVE_SP_EEPROM_PAGE_SIZE;
> +		}
> +
> +		/*
> +		 * We should never read more that 'residue' bytes
> +		 */
> +		chunk = min(chunk, residue);
> +		ret = rave_sp_eeprom_page_access(eeprom, type, offset,
> +						 data, chunk);
> +		if (ret)
> +			return ret;
> +
> +		residue -= chunk;
> +		offset  += chunk;
> +		data    += chunk;
> +	} while (residue);
> +
> +	return 0;
> +}
> +
> +static int rave_sp_eeprom_read(struct device_d *dev, const int offset,
> +			       void *val, int bytes)
> +{
> +	return rave_sp_eeprom_access(dev->parent->priv,
> +				     RAVE_SP_EEPROM_READ,
> +				     offset, val, bytes);
> +}
> +
> +static int rave_sp_eeprom_write(struct device_d *dev, const int offset,
> +				const void *val, int bytes)
> +{
> +	return rave_sp_eeprom_access(dev->parent->priv,
> +				     RAVE_SP_EEPROM_WRITE,
> +				     offset, (void *)val, bytes);
> +}
> +
> +static const struct nvmem_bus rave_sp_eeprom_nvmem_bus = {
> +	.write = rave_sp_eeprom_write,
> +	.read  = rave_sp_eeprom_read,
> +};
> +
> +static int rave_sp_eeprom_probe(struct device_d *dev)
> +{
> +	struct rave_sp *sp = dev->parent->priv;
> +	struct nvmem_config config = { 0 };
> +	struct rave_sp_eeprom *eeprom;
> +	struct nvmem_device *nvmem;
> +	u32 reg[2], size;
> +
> +	if (of_property_read_u32_array(dev->device_node,
> +				       "reg", reg, ARRAY_SIZE(reg))) {
> +		dev_err(dev, "Failed to parse \"reg\" property\n");
> +		return -EINVAL;
> +	}
> +
> +	size = reg[1];
> +	/*
> +	 * Per ICD, we have no more than 2 bytes to specify EEPROM
> +	 * page.
> +	 */
> +	if (size > U16_MAX * RAVE_SP_EEPROM_PAGE_SIZE) {
> +		dev_err(dev, "Specified size is too big\n");
> +		return -EINVAL;
> +	}
> +
> +	eeprom = xzalloc(sizeof(*eeprom));
> +	eeprom->address = reg[0];
> +	eeprom->sp      = sp;
> +
> +	dev->priv = eeprom;
> +
> +	if (size > SZ_8K)
> +		eeprom->header_size = RAVE_SP_EEPROM_HEADER_BIG;
> +	else
> +		eeprom->header_size = RAVE_SP_EEPROM_HEADER_SMALL;
> +
> +	config.name      = dev_name(dev);
> +	config.dev       = dev;
> +	config.word_size = 1;
> +	config.stride    = 1;
> +	config.size      = reg[1];
> +	config.bus       = &rave_sp_eeprom_nvmem_bus;
> +
> +	nvmem = nvmem_register(&config);
> +	if (IS_ERR(nvmem)) {
> +		free(eeprom);
> +		return PTR_ERR(nvmem);
> +	}
> +
> +	return 0;
> +}
> +
> +static __maybe_unused const struct of_device_id rave_sp_eeprom_of_match[] = {
> +	{ .compatible = "zii,rave-sp-eeprom" },
> +	{}
> +};
> +
> +static struct driver_d rave_sp_eeprom_driver = {
> +	.name = "rave-sp-eeprom",
> +	.probe = rave_sp_eeprom_probe,
> +	.of_compatible = DRV_OF_COMPAT(rave_sp_eeprom_of_match),
> +};
> +console_platform_driver(rave_sp_eeprom_driver);
> -- 
> 2.17.1
> 
> 
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