drivers/mtd/chips/map_rom.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Common code to handle map devices which are simple ROM
   4  * (C) 2000 Red Hat.
   5  */
   6
   7 #include <linux/module.h>
   8 #include <linux/types.h>
   9 #include <linux/kernel.h>
  10 #include <asm/io.h>
  11 #include <asm/byteorder.h>
  12 #include <linux/errno.h>
  13 #include <linux/slab.h>
  14 #include <linux/init.h>
  15 #include <linux/of.h>
  16 #include <linux/mtd/mtd.h>
  17 #include <linux/mtd/map.h>
  18
  19 static int maprom_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
  20 static int maprom_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
  21 static void maprom_nop (struct mtd_info *);
  22 static struct mtd_info *map_rom_probe(struct map_info *map);
  23 static int maprom_erase (struct mtd_info *mtd, struct erase_info *info);
  24 static int maprom_point (struct mtd_info *mtd, loff_t from, size_t len,
  25                          size_t *retlen, void **virt, resource_size_t *phys);
  26 static int maprom_unpoint(struct mtd_info *mtd, loff_t from, size_t len);
  27
  28
  29 static struct mtd_chip_driver maprom_chipdrv = {
  30         .probe  = map_rom_probe,
  31         .name   = "map_rom",
  32         .module = THIS_MODULE
  33 };
  34
  35 static unsigned int default_erasesize(struct map_info *map)
  36 {
  37         const __be32 *erase_size = NULL;
  38
  39         erase_size = of_get_property(map->device_node, "erase-size", NULL);
  40
  41         return !erase_size ? map->size : be32_to_cpu(*erase_size);
  42 }
  43
  44 static struct mtd_info *map_rom_probe(struct map_info *map)
  45 {
  46         struct mtd_info *mtd;
  47
  48         mtd = kzalloc(sizeof(*mtd), GFP_KERNEL);
  49         if (!mtd)
  50                 return NULL;
  51
  52         map->fldrv = &maprom_chipdrv;
  53         mtd->priv = map;
  54         mtd->name = map->name;
  55         mtd->type = MTD_ROM;
  56         mtd->size = map->size;
  57         mtd->_point = maprom_point;
  58         mtd->_unpoint = maprom_unpoint;
  59         mtd->_read = maprom_read;
  60         mtd->_write = maprom_write;
  61         mtd->_sync = maprom_nop;
  62         mtd->_erase = maprom_erase;
  63         mtd->flags = MTD_CAP_ROM;
  64         mtd->erasesize = default_erasesize(map);
  65         mtd->writesize = 1;
  66         mtd->writebufsize = 1;
  67
  68         __module_get(THIS_MODULE);
  69         return mtd;
  70 }
  71
  72
  73 static int maprom_point(struct mtd_info *mtd, loff_t from, size_t len,
  74                         size_t *retlen, void **virt, resource_size_t *phys)
  75 {
  76         struct map_info *map = mtd->priv;
  77
  78         if (!map->virt)
  79                 return -EINVAL;
  80         *virt = map->virt + from;
  81         if (phys)
  82                 *phys = map->phys + from;
  83         *retlen = len;
  84         return 0;
  85 }
  86
  87 static int maprom_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
  88 {
  89         return 0;
  90 }
  91
  92 static int maprom_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
  93 {
  94         struct map_info *map = mtd->priv;
  95
  96         map_copy_from(map, buf, from, len);
  97         *retlen = len;
  98         return 0;
  99 }
 100
 101 static void maprom_nop(struct mtd_info *mtd)
 102 {
 103         /* Nothing to see here */
 104 }
 105
 106 static int maprom_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
 107 {
 108         return -EROFS;
 109 }
 110
 111 static int maprom_erase (struct mtd_info *mtd, struct erase_info *info)
 112 {
 113         /* We do our best 8) */
 114         return -EROFS;
 115 }
 116
 117 static int __init map_rom_init(void)
 118 {
 119         register_mtd_chip_driver(&maprom_chipdrv);
 120         return 0;
 121 }
 122
 123 static void __exit map_rom_exit(void)
 124 {
 125         unregister_mtd_chip_driver(&maprom_chipdrv);
 126 }
 127
 128 module_init(map_rom_init);
 129 module_exit(map_rom_exit);
 130
 131 MODULE_LICENSE("GPL");
 132 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 133 MODULE_DESCRIPTION("MTD chip driver for ROM chips");