/*======================================================================  $Id: slram.c,v 1.2 2007/09/21 03:09:24 quy Exp $  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 contigous memory region. Therfore  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 <asm/uaccess.h>#include <linux/types.h>#include <linux/kernel.h>#include <linux/sched.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 <asm/io.h>#include <asm/system.h>#include <linux/mtd/mtd.h>#define SLRAM_MAX_DEVICES_PARAMS 6		/* 3 parameters / device */#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 MODULEstatic char *map[SLRAM_MAX_DEVICES_PARAMS];#elsestatic char *map;#endifMODULE_PARM(map, "3-" __MODULE_STRING(SLRAM_MAX_DEVICES_PARAMS) "s");MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\"");static slram_mtd_list_t *slram_mtdlist = NULL;int slram_erase(struct mtd_info *, struct erase_info *);int slram_point(struct mtd_info *, loff_t, size_t, size_t *, u_char **);void slram_unpoint(struct mtd_info *, u_char *, loff_t,	size_t);int slram_read(struct mtd_info *, loff_t, size_t, size_t *, u_char *);int slram_write(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);int slram_erase(struct mtd_info *mtd, struct erase_info *instr){	slram_priv_t *priv = mtd->priv;	if (instr->addr + instr->len > mtd->size) {		return(-EINVAL);	}		memset(priv->start + instr->addr, 0xff, instr->len);	/* This'll catch a few races. Free the thing before returning :) 	 * I don't feel at all ashamed. This kind of thing is possible anyway	 * with flash, but unlikely.	 */	instr->state = MTD_ERASE_DONE;	mtd_erase_callback(instr);	return(0);}int slram_point(struct mtd_info *mtd, loff_t from, size_t len,		size_t *retlen, u_char **mtdbuf){	slram_priv_t *priv = (slram_priv_t *)mtd->priv;	*mtdbuf = priv->start + from;	*retlen = len;	return(0);}void slram_unpoint(struct mtd_info *mtd, u_char *addr, loff_t from, size_t len){}int slram_read(struct mtd_info *mtd, loff_t from, size_t len,		size_t *retlen, u_char *buf){	slram_priv_t *priv = (slram_priv_t *)mtd->priv;		memcpy(buf, priv->start + from, len);	*retlen = len;	return(0);}int slram_write(struct mtd_info *mtd, loff_t to, size_t len,		size_t *retlen, const u_char *buf){	slram_priv_t *priv = (slram_priv_t *)mtd->priv;	memcpy(priv->start + to, buf, len);	*retlen = len;	return(0);}/*====================================================================*/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 = kmalloc(sizeof(struct mtd_info), GFP_KERNEL);	(*curmtd)->next = NULL;		if ((*curmtd)->mtdinfo)	{		memset((char *)(*curmtd)->mtdinfo, 0, sizeof(struct mtd_info));		(*curmtd)->mtdinfo->priv =			(void *)kmalloc(sizeof(slram_priv_t), GFP_KERNEL);				if (!(*curmtd)->mtdinfo->priv) {			kfree((*curmtd)->mtdinfo);			(*curmtd)->mtdinfo = NULL;		} else {			memset((*curmtd)->mtdinfo->priv,0,sizeof(slram_priv_t));		}	}	if (!(*curmtd)->mtdinfo) {		E("slram: Cannot allocate new MTD device.\n");		return(-ENOMEM);	}		if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =				ioremap(start, length))) {		E("slram: ioremap 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_CLEAR_BITS | MTD_SET_BITS |					MTD_WRITEB_WRITEABLE | MTD_VOLATILE;        (*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 = 0x0;	if (add_mtd_device((*curmtd)->mtdinfo))	{		E("slram: Failed to register new device\n");		iounmap(((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);	}void unregister_devices(void){	slram_mtd_list_t *nextitem;	while (slram_mtdlist) {		nextitem = slram_mtdlist->next;		del_mtd_device(slram_mtdlist->mtdinfo);		iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);		kfree(slram_mtdlist->mtdinfo->priv);		kfree(slram_mtdlist->mtdinfo);		kfree(slram_mtdlist);		slram_mtdlist = nextitem;	}}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);}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) - 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 ((devstart < 0) || (devlength < 0)) {		E("slram: Illegal start / length parameter.\n");		return(-EINVAL);	}		if ((devstart = register_device(devname, devstart, devlength))){		unregister_devices();		return((int)devstart);	}	return(0);}#ifndef MODULEstatic int __init mtd_slram_setup(char *str){	map = str;	return(1);}__setup("slram=", mtd_slram_setup);#endifint init_slram(void){	char *devname;	int i;#ifndef MODULE	char *devstart;	char *devlength;	i = 0;	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;		for (count = 0; (map[count]) && (count < SLRAM_MAX_DEVICES_PARAMS);			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");