drivers/mtd/devices/slram.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*======================================================================

   This driver provides a method to access memory not used by the kernel
   itself (i.e. if the kernel commandline mem=xxx is used). To actually
   use slram at least mtdblock or mtdchar is required (for block or
   character device access).

   Usage:

   if compiled as loadable module:
     modprobe slram map=<name>,<start>,<end/offset>
   if statically linked into the kernel use the following kernel cmd.line
     slram=<name>,<start>,<end/offset>

   <name>: name of the device that will be listed in /proc/mtd
   <start>: start of the memory region, decimal or hex (0xabcdef)
   <end/offset>: end of the memory region. It's possible to use +0x1234
                 to specify the offset instead of the absolute address

   NOTE:
   With slram it's only possible to map a contiguous memory region. Therefore
   if there's a device mapped somewhere in the region specified slram will
   fail to load (see kernel log if modprobe fails).

   -

   Jochen Schaeuble <psionic@psionic.de>

 ======================================================================*/


 #include <linux/module.h>
 #include <linux/uaccess.h>
 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/ptrace.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/timer.h>
 #include <linux/major.h>
 #include <linux/fs.h>
 #include <linux/ioctl.h>
 #include <linux/init.h>
 #include <linux/io.h>

 #include <linux/mtd/mtd.h>

 #define SLRAM_MAX_DEVICES_PARAMS 6		/* 3 parameters / device */
 #define SLRAM_BLK_SZ 0x4000

 #define T(fmt, args...) printk(KERN_DEBUG fmt, ## args)
 #define E(fmt, args...) printk(KERN_NOTICE fmt, ## args)

 typedef struct slram_priv {
 	u_char *start;
 	u_char *end;
 } slram_priv_t;

 typedef struct slram_mtd_list {
 	struct mtd_info *mtdinfo;
 	struct slram_mtd_list *next;
 } slram_mtd_list_t;

 #ifdef MODULE
 static char *map[SLRAM_MAX_DEVICES_PARAMS];

 module_param_array(map, charp, NULL, 0);
 MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\"");
 #else
 static char *map;
 #endif

 static slram_mtd_list_t *slram_mtdlist = NULL;

 static int slram_erase(struct mtd_info *, struct erase_info *);
 static int slram_point(struct mtd_info *, loff_t, size_t, size_t *, void **,
 		resource_size_t *);
 static int slram_unpoint(struct mtd_info *, loff_t, size_t);
 static int slram_read(struct mtd_info *, loff_t, size_t, size_t *, u_char *);
 static int slram_write(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);

 static int slram_erase(struct mtd_info *mtd, struct erase_info *instr)
 {
 	slram_priv_t *priv = mtd->priv;

 	memset(priv->start + instr->addr, 0xff, instr->len);

 	return(0);
 }

 static int slram_point(struct mtd_info *mtd, loff_t from, size_t len,
 		size_t *retlen, void **virt, resource_size_t *phys)
 {
 	slram_priv_t *priv = mtd->priv;

 	*virt = priv->start + from;
 	*retlen = len;
 	return(0);
 }

 static int slram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
 {
 	return 0;
 }

 static int slram_read(struct mtd_info *mtd, loff_t from, size_t len,
 		size_t *retlen, u_char *buf)
 {
 	slram_priv_t *priv = mtd->priv;

 	memcpy(buf, priv->start + from, len);
 	*retlen = len;
 	return(0);
 }

 static int slram_write(struct mtd_info *mtd, loff_t to, size_t len,
 		size_t *retlen, const u_char *buf)
 {
 	slram_priv_t *priv = mtd->priv;

 	memcpy(priv->start + to, buf, len);
 	*retlen = len;
 	return(0);
 }

 /*====================================================================*/

 static int register_device(char *name, unsigned long start, unsigned long length)
 {
 	slram_mtd_list_t **curmtd;

 	curmtd = &slram_mtdlist;
 	while (*curmtd) {
 		curmtd = &(*curmtd)->next;
 	}

 	*curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL);
 	if (!(*curmtd)) {
 		E("slram: Cannot allocate new MTD device.\n");
 		return(-ENOMEM);
 	}
 	(*curmtd)->mtdinfo = kzalloc(sizeof(struct mtd_info), GFP_KERNEL);
 	(*curmtd)->next = NULL;

 	if ((*curmtd)->mtdinfo)	{
 		(*curmtd)->mtdinfo->priv =
 			kzalloc(sizeof(slram_priv_t), GFP_KERNEL);

 		if (!(*curmtd)->mtdinfo->priv) {
 			kfree((*curmtd)->mtdinfo);
 			(*curmtd)->mtdinfo = NULL;
 		}
 	}

 	if (!(*curmtd)->mtdinfo) {
 		E("slram: Cannot allocate new MTD device.\n");
 		return(-ENOMEM);
 	}

 	if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =
 		memremap(start, length,
 			 MEMREMAP_WB | MEMREMAP_WT | MEMREMAP_WC))) {
 		E("slram: memremap failed\n");
 		return -EIO;
 	}
 	((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end =
 		((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length;


 	(*curmtd)->mtdinfo->name = name;
 	(*curmtd)->mtdinfo->size = length;
 	(*curmtd)->mtdinfo->flags = MTD_CAP_RAM;
 	(*curmtd)->mtdinfo->_erase = slram_erase;
 	(*curmtd)->mtdinfo->_point = slram_point;
 	(*curmtd)->mtdinfo->_unpoint = slram_unpoint;
 	(*curmtd)->mtdinfo->_read = slram_read;
 	(*curmtd)->mtdinfo->_write = slram_write;
 	(*curmtd)->mtdinfo->owner = THIS_MODULE;
 	(*curmtd)->mtdinfo->type = MTD_RAM;
 	(*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ;
 	(*curmtd)->mtdinfo->writesize = 1;

 	if (mtd_device_register((*curmtd)->mtdinfo, NULL, 0))	{
 		E("slram: Failed to register new device\n");
 		memunmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
 		kfree((*curmtd)->mtdinfo->priv);
 		kfree((*curmtd)->mtdinfo);
 		return(-EAGAIN);
 	}
 	T("slram: Registered device %s from %luKiB to %luKiB\n", name,
 			(start / 1024), ((start + length) / 1024));
 	T("slram: Mapped from 0x%p to 0x%p\n",
 			((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start,
 			((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end);
 	return(0);
 }

 static void unregister_devices(void)
 {
 	slram_mtd_list_t *nextitem;

 	while (slram_mtdlist) {
 		nextitem = slram_mtdlist->next;
 		mtd_device_unregister(slram_mtdlist->mtdinfo);
 		memunmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
 		kfree(slram_mtdlist->mtdinfo->priv);
 		kfree(slram_mtdlist->mtdinfo);
 		kfree(slram_mtdlist);
 		slram_mtdlist = nextitem;
 	}
 }

 static unsigned long handle_unit(unsigned long value, char *unit)
 {
 	if ((*unit == 'M') || (*unit == 'm')) {
 		return(value * 1024 * 1024);
 	} else if ((*unit == 'K') || (*unit == 'k')) {
 		return(value * 1024);
 	}
 	return(value);
 }

 static int parse_cmdline(char *devname, char *szstart, char *szlength)
 {
 	char *buffer;
 	unsigned long devstart;
 	unsigned long devlength;

 	if ((!devname) || (!szstart) || (!szlength)) {
 		unregister_devices();
 		return(-EINVAL);
 	}

 	devstart = simple_strtoul(szstart, &buffer, 0);
 	devstart = handle_unit(devstart, buffer);

 	if (*(szlength) != '+') {
 		devlength = simple_strtoul(szlength, &buffer, 0);
 		devlength = handle_unit(devlength, buffer);
 		if (devlength < devstart)
 			goto err_out;

 		devlength -= devstart;
 	} else {
 		devlength = simple_strtoul(szlength + 1, &buffer, 0);
 		devlength = handle_unit(devlength, buffer);
 	}
 	T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n",
 			devname, devstart, devlength);
 	if (devlength % SLRAM_BLK_SZ != 0)
 		goto err_out;

 	if ((devstart = register_device(devname, devstart, devlength))){
 		unregister_devices();
 		return((int)devstart);
 	}
 	return(0);

 err_out:
 	E("slram: Illegal length parameter.\n");
 	return(-EINVAL);
 }

 #ifndef MODULE

 static int __init mtd_slram_setup(char *str)
 {
 	map = str;
 	return(1);
 }

 __setup("slram=", mtd_slram_setup);

 #endif

 static int __init init_slram(void)
 {
 	char *devname;

 #ifndef MODULE
 	char *devstart;
 	char *devlength;

 	if (!map) {
 		E("slram: not enough parameters.\n");
 		return(-EINVAL);
 	}
 	while (map) {
 		devname = devstart = devlength = NULL;

 		if (!(devname = strsep(&map, ","))) {
 			E("slram: No devicename specified.\n");
 			break;
 		}
 		T("slram: devname = %s\n", devname);
 		if ((!map) || (!(devstart = strsep(&map, ",")))) {
 			E("slram: No devicestart specified.\n");
 		}
 		T("slram: devstart = %s\n", devstart);
 		if ((!map) || (!(devlength = strsep(&map, ",")))) {
 			E("slram: No devicelength / -end specified.\n");
 		}
 		T("slram: devlength = %s\n", devlength);
 		if (parse_cmdline(devname, devstart, devlength) != 0) {
 			return(-EINVAL);
 		}
 	}
 #else
 	int count;
 	int i;

 	for (count = 0; count < SLRAM_MAX_DEVICES_PARAMS && map[count];
 			count++) {
 	}

 	if ((count % 3 != 0) || (count == 0)) {
 		E("slram: not enough parameters.\n");
 		return(-EINVAL);
 	}
 	for (i = 0; i < (count / 3); i++) {
 		devname = map[i * 3];

 		if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) {
 			return(-EINVAL);
 		}

 	}
 #endif /* !MODULE */

 	return(0);
 }

 static void __exit cleanup_slram(void)
 {
 	unregister_devices();
 }

 module_init(init_slram);
 module_exit(cleanup_slram);

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
 MODULE_DESCRIPTION("MTD driver for uncached system RAM");
	// SPDX-License-Identifier: GPL-2.0-only
	/*======================================================================

	This driver provides a method to access memory not used by the kernel
	itself (i.e. if the kernel commandline mem=xxx is used). To actually
	use slram at least mtdblock or mtdchar is required (for block or
	character device access).

	Usage:

	if compiled as loadable module:
	modprobe slram map=<name>,<start>,<end/offset>
	if statically linked into the kernel use the following kernel cmd.line
	slram=<name>,<start>,<end/offset>

	<name>: name of the device that will be listed in /proc/mtd
	<start>: start of the memory region, decimal or hex (0xabcdef)
	<end/offset>: end of the memory region. It's possible to use +0x1234
	to specify the offset instead of the absolute address

	NOTE:
	With slram it's only possible to map a contiguous memory region. Therefore
	if there's a device mapped somewhere in the region specified slram will
	fail to load (see kernel log if modprobe fails).

	-

	Jochen Schaeuble <psionic@psionic.de>

	======================================================================*/


	#include <linux/module.h>
	#include <linux/uaccess.h>
	#include <linux/types.h>
	#include <linux/kernel.h>
	#include <linux/ptrace.h>
	#include <linux/slab.h>
	#include <linux/string.h>
	#include <linux/timer.h>
	#include <linux/major.h>
	#include <linux/fs.h>
	#include <linux/ioctl.h>
	#include <linux/init.h>
	#include <linux/io.h>

	#include <linux/mtd/mtd.h>

	#define SLRAM_MAX_DEVICES_PARAMS 6 /* 3 parameters / device */
	#define SLRAM_BLK_SZ 0x4000

	#define T(fmt, args...) printk(KERN_DEBUG fmt, ## args)
	#define E(fmt, args...) printk(KERN_NOTICE fmt, ## args)

	typedef struct slram_priv {
	u_char *start;
	u_char *end;
	} slram_priv_t;

	typedef struct slram_mtd_list {
	struct mtd_info *mtdinfo;
	struct slram_mtd_list *next;
	} slram_mtd_list_t;

	#ifdef MODULE
	static char *map[SLRAM_MAX_DEVICES_PARAMS];

	module_param_array(map, charp, NULL, 0);
	MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\"");
	#else
	static char *map;
	#endif

	static slram_mtd_list_t *slram_mtdlist = NULL;

	static int slram_erase(struct mtd_info , struct erase_info );
	static int slram_point(struct mtd_info , loff_t, size_t, size_t , void **,
	resource_size_t *);
	static int slram_unpoint(struct mtd_info *, loff_t, size_t);
	static int slram_read(struct mtd_info , loff_t, size_t, size_t , u_char *);
	static int slram_write(struct mtd_info , loff_t, size_t, size_t , const u_char *);

	static int slram_erase(struct mtd_info mtd, struct erase_info instr)
	{
	slram_priv_t *priv = mtd->priv;

	memset(priv->start + instr->addr, 0xff, instr->len);

	return(0);
	}

	static int slram_point(struct mtd_info *mtd, loff_t from, size_t len,
	size_t retlen, void virt, resource_size_t phys)
	{
	slram_priv_t *priv = mtd->priv;

	*virt = priv->start + from;
	*retlen = len;
	return(0);
	}

	static int slram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
	{
	return 0;
	}

	static int slram_read(struct mtd_info *mtd, loff_t from, size_t len,
	size_t retlen, u_char buf)
	{
	slram_priv_t *priv = mtd->priv;

	memcpy(buf, priv->start + from, len);
	*retlen = len;
	return(0);
	}

	static int slram_write(struct mtd_info *mtd, loff_t to, size_t len,
	size_t retlen, const u_char buf)
	{
	slram_priv_t *priv = mtd->priv;

	memcpy(priv->start + to, buf, len);
	*retlen = len;
	return(0);
	}

	/====================================================================/

	static int register_device(char *name, unsigned long start, unsigned long length)
	{
	slram_mtd_list_t **curmtd;

	curmtd = &slram_mtdlist;
	while (*curmtd) {
	curmtd = &(*curmtd)->next;
	}

	*curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL);
	if (!(*curmtd)) {
	E("slram: Cannot allocate new MTD device.\n");
	return(-ENOMEM);
	}
	(*curmtd)->mtdinfo = kzalloc(sizeof(struct mtd_info), GFP_KERNEL);
	(*curmtd)->next = NULL;

	if ((*curmtd)->mtdinfo) {
	(*curmtd)->mtdinfo->priv =
	kzalloc(sizeof(slram_priv_t), GFP_KERNEL);

	if (!(*curmtd)->mtdinfo->priv) {
	kfree((*curmtd)->mtdinfo);
	(*curmtd)->mtdinfo = NULL;
	}
	}

	if (!(*curmtd)->mtdinfo) {
	E("slram: Cannot allocate new MTD device.\n");
	return(-ENOMEM);
	}

	if (!(((slram_priv_t )(curmtd)->mtdinfo->priv)->start =
	memremap(start, length,
	MEMREMAP_WB \| MEMREMAP_WT \| MEMREMAP_WC))) {
	E("slram: memremap failed\n");
	return -EIO;
	}
	((slram_priv_t )(curmtd)->mtdinfo->priv)->end =
	((slram_priv_t )(curmtd)->mtdinfo->priv)->start + length;


	(*curmtd)->mtdinfo->name = name;
	(*curmtd)->mtdinfo->size = length;
	(*curmtd)->mtdinfo->flags = MTD_CAP_RAM;
	(*curmtd)->mtdinfo->_erase = slram_erase;
	(*curmtd)->mtdinfo->_point = slram_point;
	(*curmtd)->mtdinfo->_unpoint = slram_unpoint;
	(*curmtd)->mtdinfo->_read = slram_read;
	(*curmtd)->mtdinfo->_write = slram_write;
	(*curmtd)->mtdinfo->owner = THIS_MODULE;
	(*curmtd)->mtdinfo->type = MTD_RAM;
	(*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ;
	(*curmtd)->mtdinfo->writesize = 1;

	if (mtd_device_register((*curmtd)->mtdinfo, NULL, 0)) {
	E("slram: Failed to register new device\n");
	memunmap(((slram_priv_t )(curmtd)->mtdinfo->priv)->start);
	kfree((*curmtd)->mtdinfo->priv);
	kfree((*curmtd)->mtdinfo);
	return(-EAGAIN);
	}
	T("slram: Registered device %s from %luKiB to %luKiB\n", name,
	(start / 1024), ((start + length) / 1024));
	T("slram: Mapped from 0x%p to 0x%p\n",
	((slram_priv_t )(curmtd)->mtdinfo->priv)->start,
	((slram_priv_t )(curmtd)->mtdinfo->priv)->end);
	return(0);
	}

	static void unregister_devices(void)
	{
	slram_mtd_list_t *nextitem;

	while (slram_mtdlist) {
	nextitem = slram_mtdlist->next;
	mtd_device_unregister(slram_mtdlist->mtdinfo);
	memunmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
	kfree(slram_mtdlist->mtdinfo->priv);
	kfree(slram_mtdlist->mtdinfo);
	kfree(slram_mtdlist);
	slram_mtdlist = nextitem;
	}
	}

	static unsigned long handle_unit(unsigned long value, char *unit)
	{
	if ((unit == 'M') \|\| (unit == 'm')) {
	return(value * 1024 * 1024);
	} else if ((unit == 'K') \|\| (unit == 'k')) {
	return(value * 1024);
	}
	return(value);
	}

	static int parse_cmdline(char devname, char szstart, char *szlength)
	{
	char *buffer;
	unsigned long devstart;
	unsigned long devlength;

	if ((!devname) \|\| (!szstart) \|\| (!szlength)) {
	unregister_devices();
	return(-EINVAL);
	}

	devstart = simple_strtoul(szstart, &buffer, 0);
	devstart = handle_unit(devstart, buffer);

	if (*(szlength) != '+') {
	devlength = simple_strtoul(szlength, &buffer, 0);
	devlength = handle_unit(devlength, buffer);
	if (devlength < devstart)
	goto err_out;

	devlength -= devstart;
	} else {
	devlength = simple_strtoul(szlength + 1, &buffer, 0);
	devlength = handle_unit(devlength, buffer);
	}
	T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n",
	devname, devstart, devlength);
	if (devlength % SLRAM_BLK_SZ != 0)
	goto err_out;

	if ((devstart = register_device(devname, devstart, devlength))){
	unregister_devices();
	return((int)devstart);
	}
	return(0);

	err_out:
	E("slram: Illegal length parameter.\n");
	return(-EINVAL);
	}

	#ifndef MODULE

	static int __init mtd_slram_setup(char *str)
	{
	map = str;
	return(1);
	}

	__setup("slram=", mtd_slram_setup);

	#endif

	static int __init init_slram(void)
	{
	char *devname;

	#ifndef MODULE
	char *devstart;
	char *devlength;

	if (!map) {
	E("slram: not enough parameters.\n");
	return(-EINVAL);
	}
	while (map) {
	devname = devstart = devlength = NULL;

	if (!(devname = strsep(&map, ","))) {
	E("slram: No devicename specified.\n");
	break;
	}
	T("slram: devname = %s\n", devname);
	if ((!map) \|\| (!(devstart = strsep(&map, ",")))) {
	E("slram: No devicestart specified.\n");
	}
	T("slram: devstart = %s\n", devstart);
	if ((!map) \|\| (!(devlength = strsep(&map, ",")))) {
	E("slram: No devicelength / -end specified.\n");
	}
	T("slram: devlength = %s\n", devlength);
	if (parse_cmdline(devname, devstart, devlength) != 0) {
	return(-EINVAL);
	}
	}
	#else
	int count;
	int i;

	for (count = 0; count < SLRAM_MAX_DEVICES_PARAMS && map[count];
	count++) {
	}

	if ((count % 3 != 0) \|\| (count == 0)) {
	E("slram: not enough parameters.\n");
	return(-EINVAL);
	}
	for (i = 0; i < (count / 3); i++) {
	devname = map[i * 3];

	if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) {
	return(-EINVAL);
	}

	}
	#endif /* !MODULE */

	return(0);
	}

	static void __exit cleanup_slram(void)
	{
	unregister_devices();
	}

	module_init(init_slram);
	module_exit(cleanup_slram);

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
	MODULE_DESCRIPTION("MTD driver for uncached system RAM");