/**
 * $Id: phram.c,v 1.11 2005/01/05 18:05:13 dwmw2 Exp $
 *
 * Copyright (c) ????           Jochen Schäuble <psionic@psionic.de>
 * Copyright (c) 2003-2004      Jörn Engel <joern@wh.fh-wedel.de>
 *
 * Usage:
 *
 * one commend line parameter per device, each in the form:
 *   phram=<name>,<start>,<len>
 * <name> may be up to 63 characters.
 * <start> and <len> can be octal, decimal or hexadecimal.  If followed
 * by "ki", "Mi" or "Gi", the numbers will be interpreted as kilo, mega or
 * gigabytes.
 *
 * Example:
 *      phram=swap,64Mi,128Mi phram=test,900Mi,1Mi
 *
 */

#include <asm/io.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/mtd/mtd.h>

#define ERROR(fmt, args...) printk(KERN_ERR "phram: " fmt , ## args)

struct phram_mtd_list {
        struct mtd_info mtd;
        struct list_head list;
};

static LIST_HEAD(phram_list);



static int phram_erase(struct mtd_info *mtd, struct erase_info *instr)
{
        u_char *start = mtd->priv;

        if (instr->addr + instr->len > mtd->size)
                return -EINVAL;
        
        memset(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;
}

static int phram_point(struct mtd_info *mtd, loff_t from, size_t len,
                size_t *retlen, u_char **mtdbuf)
{
        u_char *start = mtd->priv;

        if (from + len > mtd->size)
                return -EINVAL;
        
        *mtdbuf = start + from;
        *retlen = len;
        return 0;
}

static void phram_unpoint(struct mtd_info *mtd, u_char *addr, loff_t from, size_t len)
{
}

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

        if (from + len > mtd->size)
                return -EINVAL;
        
        memcpy(buf, start + from, len);

        *retlen = len;
        return 0;
}

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

        if (to + len > mtd->size)
                return -EINVAL;
        
        memcpy(start + to, buf, len);

        *retlen = len;
        return 0;
}



static void unregister_devices(void)
{
        struct phram_mtd_list *this;

        list_for_each_entry(this, &phram_list, list) {
                del_mtd_device(&this->mtd);
                iounmap(this->mtd.priv);
                kfree(this);
        }
}

static int register_device(char *name, unsigned long start, unsigned long len)
{
        struct phram_mtd_list *new;
        int ret = -ENOMEM;

        new = kmalloc(sizeof(*new), GFP_KERNEL);
        if (!new)
                goto out0;

        memset(new, 0, sizeof(*new));

        ret = -EIO;
        new->mtd.priv = ioremap(start, len);
        if (!new->mtd.priv) {
                ERROR("ioremap failed\n");
                goto out1;
        }


        new->mtd.name = name;
        new->mtd.size = len;
        new->mtd.flags = MTD_CAP_RAM | MTD_ERASEABLE | MTD_VOLATILE;
        new->mtd.erase = phram_erase;
        new->mtd.point = phram_point;
        new->mtd.unpoint = phram_unpoint;
        new->mtd.read = phram_read;
        new->mtd.write = phram_write;
        new->mtd.owner = THIS_MODULE;
        new->mtd.type = MTD_RAM;
        new->mtd.erasesize = 0;

        ret = -EAGAIN;
        if (add_mtd_device(&new->mtd)) {
                ERROR("Failed to register new device\n");
                goto out2;
        }

        list_add_tail(&new->list, &phram_list);
        return 0;       

out2:
        iounmap(new->mtd.priv);
out1:
        kfree(new);
out0:
        return ret;
}

static int ustrtoul(const char *cp, char **endp, unsigned int base)
{
        unsigned long result = simple_strtoul(cp, endp, base);

        switch (**endp) {
        case 'G':
                result *= 1024;
        case 'M':
                result *= 1024;
        case 'k':
                result *= 1024;
        /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
                if ((*endp)[1] == 'i')
                        (*endp) += 2;
        }
        return result;
}

static int parse_num32(uint32_t *num32, const char *token)
{
        char *endp;
        unsigned long n;

        n = ustrtoul(token, &endp, 0);
        if (*endp)
                return -EINVAL;

        *num32 = n;
        return 0;
}

static int parse_name(char **pname, const char *token)
{
        size_t len;
        char *name;

        len = strlen(token) + 1;
        if (len > 64)
                return -ENOSPC;

        name = kmalloc(len, GFP_KERNEL);
        if (!name)
                return -ENOMEM;

        strcpy(name, token);

        *pname = name;
        return 0;
}

#define parse_err(fmt, args...) do {    \
        ERROR(fmt , ## args);   \
        return 0;               \
} while (0)

static int phram_setup(const char *val, struct kernel_param *kp)
{
        char buf[64+12+12], *str = buf;
        char *token[3];
        char *name;
        uint32_t start;
        uint32_t len;
        int i, ret;

        if (strnlen(val, sizeof(buf)) >= sizeof(buf))
                parse_err("parameter too long\n");

        strcpy(str, val);

        for (i=0; i<3; i++)
                token[i] = strsep(&str, ",");

        if (str)
                parse_err("too many arguments\n");

        if (!token[2])
                parse_err("not enough arguments\n");

        ret = parse_name(&name, token[0]);
        if (ret == -ENOMEM)
                parse_err("out of memory\n");
        if (ret == -ENOSPC)
                parse_err("name too long\n");
        if (ret)
                return 0;

        ret = parse_num32(&start, token[1]);
        if (ret)
                parse_err("illegal start address\n");

        ret = parse_num32(&len, token[2]);
        if (ret)
                parse_err("illegal device length\n");

        register_device(name, start, len);

        return 0;
}

module_param_call(phram, phram_setup, NULL, NULL, 000);
MODULE_PARM_DESC(phram,"Memory region to map. \"map=<name>,<start>,<length>\"");


static int __init init_phram(void)
{
        return 0;
}

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

module_init(init_phram);
module_exit(cleanup_phram);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jörn Engel <joern@wh.fh-wedel.de>");
MODULE_DESCRIPTION("MTD driver for physical RAM");