// SPDX-License-Identifier: GPL-2.0
/*
 * Common code to handle map devices which are simple ROM
 * (C) 2000 Red Hat.
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <asm/io.h>
#include <asm/byteorder.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/of.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/map.h>

static int maprom_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
static int maprom_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
static void maprom_nop (struct mtd_info *);
static struct mtd_info *map_rom_probe(struct map_info *map);
static int maprom_erase (struct mtd_info *mtd, struct erase_info *info);
static int maprom_point (struct mtd_info *mtd, loff_t from, size_t len,
                         size_t *retlen, void **virt, resource_size_t *phys);
static int maprom_unpoint(struct mtd_info *mtd, loff_t from, size_t len);


static struct mtd_chip_driver maprom_chipdrv = {
        .probe  = map_rom_probe,
        .name   = "map_rom",
        .module = THIS_MODULE
};

static unsigned int default_erasesize(struct map_info *map)
{
        const __be32 *erase_size = NULL;

        erase_size = of_get_property(map->device_node, "erase-size", NULL);

        return !erase_size ? map->size : be32_to_cpu(*erase_size);
}

static struct mtd_info *map_rom_probe(struct map_info *map)
{
        struct mtd_info *mtd;

        mtd = kzalloc_obj(*mtd);
        if (!mtd)
                return NULL;

        map->fldrv = &maprom_chipdrv;
        mtd->priv = map;
        mtd->name = map->name;
        mtd->type = MTD_ROM;
        mtd->size = map->size;
        mtd->_point = maprom_point;
        mtd->_unpoint = maprom_unpoint;
        mtd->_read = maprom_read;
        mtd->_write = maprom_write;
        mtd->_sync = maprom_nop;
        mtd->_erase = maprom_erase;
        mtd->flags = MTD_CAP_ROM;
        mtd->erasesize = default_erasesize(map);
        mtd->writesize = 1;
        mtd->writebufsize = 1;

        __module_get(THIS_MODULE);
        return mtd;
}


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

        if (!map->virt)
                return -EINVAL;
        *virt = map->virt + from;
        if (phys)
                *phys = map->phys + from;
        *retlen = len;
        return 0;
}

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

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

        map_copy_from(map, buf, from, len);
        *retlen = len;
        return 0;
}

static void maprom_nop(struct mtd_info *mtd)
{
        /* Nothing to see here */
}

static int maprom_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
{
        return -EROFS;
}

static int maprom_erase (struct mtd_info *mtd, struct erase_info *info)
{
        /* We do our best 8) */
        return -EROFS;
}

static int __init map_rom_init(void)
{
        register_mtd_chip_driver(&maprom_chipdrv);
        return 0;
}

static void __exit map_rom_exit(void)
{
        unregister_mtd_chip_driver(&maprom_chipdrv);
}

module_init(map_rom_init);
module_exit(map_rom_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
MODULE_DESCRIPTION("MTD chip driver for ROM chips");