Commit ffad5603 authored by Patrick O'Grady's avatar Patrick O'Grady Committed by Miquel Raynal
Browse files

mtd: phram: Allow the user to set the erase page size. 



Permit the user to specify the erase page size as a parameter.
This solves two problems:

- phram can access images made by mkfs.jffs2.  mkfs.jffs2 won't
create images with erase sizes less than 8KiB; many architectures
define PAGE_SIZE as 4KiB.

- Allows more effective use of small capacity devices.  JFFS2
needs somewhere between 2 and 5 empty pages for garbage collection;
and for an NVRAM part with only 32KiB of space, a smaller erase page
allows much better utilization in applications where garbage collection
is important.

Signed-off-by: default avatarPatrick O'Grady <patrick@baymotion.com>
Reviewed-by: default avatarJoern Engel <joern@logfs.org>
Link: https://lore.kernel.org/lkml/CAJ7m5OqYv_=JB9NhHsqBsa8YU0DFRoP7C+W10PY22wonAGJK=A@mail.gmail.com/


[Guohua Zhong: fix token array index out of bounds and update patch for kernel master branch]
Signed-off-by: default avatarGuohua Zhong <zhongguohua1@huawei.com>
Signed-off-by: default avatarMiquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20201207095529.20896-1-zhongguohua1@huawei.com
parent 1ca71415

drivers/mtd/devices/phram.c

+34 −18
Original line number Diff line number Diff line
@@ -6,14 +6,14 @@ 
 * Usage:

 *

 * one commend line parameter per device, each in the form:

 *   phram=<name>,<start>,<len>

 *   phram=<name>,<start>,<len>[,<erasesize>]

 * <name> may be up to 63 characters.

 * <start> and <len> can be octal, decimal or hexadecimal.  If followed

 * <start>, <len>, and <erasesize> can be octal, decimal or hexadecimal.  If followed

 * by "ki", "Mi" or "Gi", the numbers will be interpreted as kilo, mega or

 * gigabytes.

 * gigabytes. <erasesize> is optional and defaults to PAGE_SIZE.

 *

 * Example:

 *	phram=swap,64Mi,128Mi phram=test,900Mi,1Mi

 *	phram=swap,64Mi,128Mi phram=test,900Mi,1Mi,64Ki

 */



#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -26,6 +26,7 @@ 
#include <linux/moduleparam.h>

#include <linux/slab.h>

#include <linux/mtd/mtd.h>

#include <asm/div64.h>



struct phram_mtd_list {

	struct mtd_info mtd;
@@ -88,7 +89,7 @@ static void unregister_devices(void) 
	}

}



static int register_device(char *name, phys_addr_t start, size_t len)

static int register_device(char *name, phys_addr_t start, size_t len, uint32_t erasesize)

{

	struct phram_mtd_list *new;

	int ret = -ENOMEM;
@@ -115,7 +116,7 @@ static int register_device(char *name, phys_addr_t start, size_t len) 
	new->mtd._write = phram_write;

	new->mtd.owner = THIS_MODULE;

	new->mtd.type = MTD_RAM;

	new->mtd.erasesize = PAGE_SIZE;

	new->mtd.erasesize = erasesize;

	new->mtd.writesize = 1;



	ret = -EAGAIN;
@@ -204,22 +205,23 @@ static inline void kill_final_newline(char *str) 
static int phram_init_called;

/*

 * This shall contain the module parameter if any. It is of the form:

 * - phram=<device>,<address>,<size> for module case

 * - phram.phram=<device>,<address>,<size> for built-in case

 * We leave 64 bytes for the device name, 20 for the address and 20 for the

 * size.

 * Example: phram.phram=rootfs,0xa0000000,512Mi

 * - phram=<device>,<address>,<size>[,<erasesize>] for module case

 * - phram.phram=<device>,<address>,<size>[,<erasesize>] for built-in case

 * We leave 64 bytes for the device name, 20 for the address , 20 for the

 * size and 20 for the erasesize.

 * Example: phram.phram=rootfs,0xa0000000,512Mi,65536

 */

static char phram_paramline[64 + 20 + 20];

static char phram_paramline[64 + 20 + 20 + 20];

#endif



static int phram_setup(const char *val)

{

	char buf[64 + 20 + 20], *str = buf;

	char *token[3];

	char buf[64 + 20 + 20 + 20], *str = buf;

	char *token[4];

	char *name;

	uint64_t start;

	uint64_t len;

	uint64_t erasesize = PAGE_SIZE;

	int i, ret;



	if (strnlen(val, sizeof(buf)) >= sizeof(buf))
@@ -228,7 +230,7 @@ static int phram_setup(const char *val) 
	strcpy(str, val);

	kill_final_newline(str);



	for (i = 0; i < 3; i++)

	for (i = 0; i < 4; i++)

		token[i] = strsep(&str, ",");



	if (str)
@@ -253,11 +255,25 @@ static int phram_setup(const char *val) 
		goto error;

	}



	ret = register_device(name, start, len);

	if (token[3]) {

		ret = parse_num64(&erasesize, token[3]);

		if (ret) {

			parse_err("illegal erasesize\n");

			goto error;

		}

	}



	if (len == 0 || erasesize == 0 || erasesize > len

	    || erasesize > UINT_MAX || do_div(len, (uint32_t)erasesize) != 0) {

		parse_err("illegal erasesize or len\n");

		goto error;

	}



	ret = register_device(name, start, len, (uint32_t)erasesize);

	if (ret)

		goto error;



	pr_info("%s device: %#llx at %#llx\n", name, len, start);

	pr_info("%s device: %#llx at %#llx for erasesize %#llx\n", name, len, start, erasesize);

	return 0;



error:
@@ -298,7 +314,7 @@ static int phram_param_call(const char *val, const struct kernel_param *kp) 
}



module_param_call(phram, phram_param_call, NULL, NULL, 0200);

MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>\"");

MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>[,<erasesize>]\"");





static int __init init_phram(void)

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