Commit c4dfa25a authored by Alban Bedel's avatar Alban Bedel Committed by Greg Kroah-Hartman
Browse files

mtd: add support for reading MTD devices via the nvmem API 



Allow drivers that use the nvmem API to read data stored on MTD devices.
For this the mtd devices are registered as read-only NVMEM providers.

We don't support device tree systems for now.

Signed-off-by: default avatarAlban Bedel <albeu@free.fr>
[Bartosz:
  - include linux/nvmem-provider.h
  - set the name of the nvmem provider
  - set no_of_node to true in nvmem_config
  - don't check the return value of nvmem_unregister() - it cannot fail
  - tweaked the commit message]
Signed-off-by: default avatarBartosz Golaszewski <bgolaszewski@baylibre.com>
Acked-by: default avatarBoris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 517f14d9

drivers/mtd/Kconfig

+1 −0
Original line number Diff line number Diff line 
menuconfig MTD

	tristate "Memory Technology Device (MTD) support"

	imply NVMEM

	help

	  Memory Technology Devices are flash, RAM and similar chips, often

	  used for solid state file systems on embedded devices. This option

drivers/mtd/mtdcore.c

+56 −0
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ 
#include <linux/reboot.h>

#include <linux/leds.h>

#include <linux/debugfs.h>

#include <linux/nvmem-provider.h>



#include <linux/mtd/mtd.h>

#include <linux/mtd/partitions.h>
@@ -488,6 +489,50 @@ int mtd_pairing_groups(struct mtd_info *mtd) 
}

EXPORT_SYMBOL_GPL(mtd_pairing_groups);



static int mtd_nvmem_reg_read(void *priv, unsigned int offset,

			      void *val, size_t bytes)

{

	struct mtd_info *mtd = priv;

	size_t retlen;

	int err;



	err = mtd_read(mtd, offset, bytes, &retlen, val);

	if (err && err != -EUCLEAN)

		return err;



	return retlen == bytes ? 0 : -EIO;

}



static int mtd_nvmem_add(struct mtd_info *mtd)

{

	struct nvmem_config config = {};



	config.dev = &mtd->dev;

	config.name = mtd->name;

	config.owner = THIS_MODULE;

	config.reg_read = mtd_nvmem_reg_read;

	config.size = mtd->size;

	config.word_size = 1;

	config.stride = 1;

	config.read_only = true;

	config.root_only = true;

	config.no_of_node = true;

	config.priv = mtd;



	mtd->nvmem = nvmem_register(&config);

	if (IS_ERR(mtd->nvmem)) {

		/* Just ignore if there is no NVMEM support in the kernel */

		if (PTR_ERR(mtd->nvmem) == -ENOSYS) {

			mtd->nvmem = NULL;

		} else {

			dev_err(&mtd->dev, "Failed to register NVMEM device\n");

			return PTR_ERR(mtd->nvmem);

		}

	}



	return 0;

}



static struct dentry *dfs_dir_mtd;



/**
@@ -570,6 +615,11 @@ int add_mtd_device(struct mtd_info *mtd) 
	if (error)

		goto fail_added;



	/* Add the nvmem provider */

	error = mtd_nvmem_add(mtd);

	if (error)

		goto fail_nvmem_add;



	if (!IS_ERR_OR_NULL(dfs_dir_mtd)) {

		mtd->dbg.dfs_dir = debugfs_create_dir(dev_name(&mtd->dev), dfs_dir_mtd);

		if (IS_ERR_OR_NULL(mtd->dbg.dfs_dir)) {
@@ -595,6 +645,8 @@ int add_mtd_device(struct mtd_info *mtd) 
	__module_get(THIS_MODULE);

	return 0;



fail_nvmem_add:

	device_unregister(&mtd->dev);

fail_added:

	of_node_put(mtd_get_of_node(mtd));

	idr_remove(&mtd_idr, i);
@@ -637,6 +689,10 @@ int del_mtd_device(struct mtd_info *mtd) 
		       mtd->index, mtd->name, mtd->usecount);

		ret = -EBUSY;

	} else {

		/* Try to remove the NVMEM provider */

		if (mtd->nvmem)

			nvmem_unregister(mtd->nvmem);



		device_unregister(&mtd->dev);



		idr_remove(&mtd_idr, mtd->index);

include/linux/mtd/mtd.h

+2 −0
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ 
#include <linux/notifier.h>

#include <linux/device.h>

#include <linux/of.h>

#include <linux/nvmem-provider.h>



#include <mtd/mtd-abi.h>
@@ -341,6 +342,7 @@ struct mtd_info { 
	struct device dev;

	int usecount;

	struct mtd_debug_info dbg;

	struct nvmem_device *nvmem;

};



int mtd_ooblayout_ecc(struct mtd_info *mtd, int section,

CRA Git | Maintained and supported by SUSTech CRA and CCSE