/*
 * mtdram - a test mtd device
 * Author: Alexander Larsson <alex@cendio.se>
 *
 * Copyright (c) 1999 Alexander Larsson <alex@cendio.se>
 * Copyright (c) 2005 Joern Engel <joern@wh.fh-wedel.de>
 *
 * This code is GPL
 *
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/ioport.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/mtdram.h>

static unsigned long total_size = CONFIG_MTDRAM_TOTAL_SIZE;
static unsigned long erase_size = CONFIG_MTDRAM_ERASE_SIZE;
static unsigned long writebuf_size = 64;
#define MTDRAM_TOTAL_SIZE (total_size * 1024)
#define MTDRAM_ERASE_SIZE (erase_size * 1024)

module_param(total_size, ulong, 0);
MODULE_PARM_DESC(total_size, "Total device size in KiB");
module_param(erase_size, ulong, 0);
MODULE_PARM_DESC(erase_size, "Device erase block size in KiB");
module_param(writebuf_size, ulong, 0);
MODULE_PARM_DESC(writebuf_size, "Device write buf size in Bytes (Default: 64)");

// We could store these in the mtd structure, but we only support 1 device..
static struct mtd_info *mtd_info;

static int check_offs_len(struct mtd_info *mtd, loff_t ofs, uint64_t len)
{
        int ret = 0;

        /* Start address must align on block boundary */
        if (mtd_mod_by_eb(ofs, mtd)) {
                pr_debug("%s: unaligned address\n", __func__);
                ret = -EINVAL;
        }

        /* Length must align on block boundary */
        if (mtd_mod_by_eb(len, mtd)) {
                pr_debug("%s: length not block aligned\n", __func__);
                ret = -EINVAL;
        }

        return ret;
}

static int ram_erase(struct mtd_info *mtd, struct erase_info *instr)
{
        if (check_offs_len(mtd, instr->addr, instr->len))
                return -EINVAL;
        memset((char *)mtd->priv + instr->addr, 0xff, instr->len);

        return 0;
}

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

        if (phys) {
                /* limit retlen to the number of contiguous physical pages */
                unsigned long page_ofs = offset_in_page(*virt);
                void *addr = *virt - page_ofs;
                unsigned long pfn1, pfn0 = vmalloc_to_pfn(addr);

                *phys = __pfn_to_phys(pfn0) + page_ofs;
                len += page_ofs;
                while (len > PAGE_SIZE) {
                        len -= PAGE_SIZE;
                        addr += PAGE_SIZE;
                        pfn0++;
                        pfn1 = vmalloc_to_pfn(addr);
                        if (pfn1 != pfn0) {
                                *retlen = addr - *virt;
                                break;
                        }
                }
        }

        return 0;
}

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

static int ram_read(struct mtd_info *mtd, loff_t from, size_t len,
                size_t *retlen, u_char *buf)
{
        memcpy(buf, mtd->priv + from, len);
        *retlen = len;
        return 0;
}

static int ram_write(struct mtd_info *mtd, loff_t to, size_t len,
                size_t *retlen, const u_char *buf)
{
        memcpy((char *)mtd->priv + to, buf, len);
        *retlen = len;
        return 0;
}

static void __exit cleanup_mtdram(void)
{
        if (mtd_info) {
                mtd_device_unregister(mtd_info);
                vfree(mtd_info->priv);
                kfree(mtd_info);
        }
}

int mtdram_init_device(struct mtd_info *mtd, void *mapped_address,
                unsigned long size, const char *name)
{
        memset(mtd, 0, sizeof(*mtd));

        /* Setup the MTD structure */
        mtd->name = name;
        mtd->type = MTD_RAM;
        mtd->flags = MTD_CAP_RAM;
        mtd->size = size;
        mtd->writesize = 1;
        mtd->writebufsize = writebuf_size;
        mtd->erasesize = MTDRAM_ERASE_SIZE;
        mtd->priv = mapped_address;

        mtd->owner = THIS_MODULE;
        mtd->_erase = ram_erase;
        mtd->_point = ram_point;
        mtd->_unpoint = ram_unpoint;
        mtd->_read = ram_read;
        mtd->_write = ram_write;

        if (mtd_device_register(mtd, NULL, 0))
                return -EIO;

        return 0;
}

static int __init init_mtdram(void)
{
        void *addr;
        int err;

        if (!total_size)
                return -EINVAL;

        /* Allocate some memory */
        mtd_info = kmalloc_obj(struct mtd_info);
        if (!mtd_info)
                return -ENOMEM;

        addr = vmalloc(MTDRAM_TOTAL_SIZE);
        if (!addr) {
                kfree(mtd_info);
                mtd_info = NULL;
                return -ENOMEM;
        }
        err = mtdram_init_device(mtd_info, addr, MTDRAM_TOTAL_SIZE, "mtdram test device");
        if (err) {
                vfree(addr);
                kfree(mtd_info);
                mtd_info = NULL;
                return err;
        }
        memset(mtd_info->priv, 0xff, MTDRAM_TOTAL_SIZE);
        return err;
}

module_init(init_mtdram);
module_exit(cleanup_mtdram);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Alexander Larsson <alexl@redhat.com>");
MODULE_DESCRIPTION("Simulated MTD driver for testing");