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

  $Id: slram.c,v 1.1.1.1 2004-04-15 01:52:00 phoenix 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 MODULE

static char *map[SLRAM_MAX_DEVICES_PARAMS];

#else

static char *map;

#endif

MODULE_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;

        if (instr->callback) {

                (*(instr->callback))(instr);

        }

        else {

                kfree(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->module = 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 MODULE

static int __init mtd_slram_setup(char *str)

{

        map = str;

        return(1);

}

__setup("slram=", mtd_slram_setup);

#endif

int 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");