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1// SPDX-License-Identifier: GPL-2.02/*3 * Common code to handle map devices which are simple RAM4 * (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/mtd/mtd.h>16#include <linux/mtd/map.h>17 18 19static int mapram_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);20static int mapram_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);21static int mapram_erase (struct mtd_info *, struct erase_info *);22static void mapram_nop (struct mtd_info *);23static struct mtd_info *map_ram_probe(struct map_info *map);24static int mapram_point (struct mtd_info *mtd, loff_t from, size_t len,25 size_t *retlen, void **virt, resource_size_t *phys);26static int mapram_unpoint(struct mtd_info *mtd, loff_t from, size_t len);27 28 29static struct mtd_chip_driver mapram_chipdrv = {30 .probe = map_ram_probe,31 .name = "map_ram",32 .module = THIS_MODULE33};34 35static struct mtd_info *map_ram_probe(struct map_info *map)36{37 struct mtd_info *mtd;38 39 /* Check the first byte is RAM */40#if 041 map_write8(map, 0x55, 0);42 if (map_read8(map, 0) != 0x55)43 return NULL;44 45 map_write8(map, 0xAA, 0);46 if (map_read8(map, 0) != 0xAA)47 return NULL;48 49 /* Check the last byte is RAM */50 map_write8(map, 0x55, map->size-1);51 if (map_read8(map, map->size-1) != 0x55)52 return NULL;53 54 map_write8(map, 0xAA, map->size-1);55 if (map_read8(map, map->size-1) != 0xAA)56 return NULL;57#endif58 /* OK. It seems to be RAM. */59 60 mtd = kzalloc(sizeof(*mtd), GFP_KERNEL);61 if (!mtd)62 return NULL;63 64 map->fldrv = &mapram_chipdrv;65 mtd->priv = map;66 mtd->name = map->name;67 mtd->type = MTD_RAM;68 mtd->size = map->size;69 mtd->_erase = mapram_erase;70 mtd->_read = mapram_read;71 mtd->_write = mapram_write;72 mtd->_panic_write = mapram_write;73 mtd->_sync = mapram_nop;74 mtd->flags = MTD_CAP_RAM;75 mtd->writesize = 1;76 77 /* Disable direct access when NO_XIP is set */78 if (map->phys != NO_XIP) {79 mtd->_point = mapram_point;80 mtd->_unpoint = mapram_unpoint;81 }82 83 mtd->erasesize = PAGE_SIZE;84 while(mtd->size & (mtd->erasesize - 1))85 mtd->erasesize >>= 1;86 87 __module_get(THIS_MODULE);88 return mtd;89}90 91static int mapram_point(struct mtd_info *mtd, loff_t from, size_t len,92 size_t *retlen, void **virt, resource_size_t *phys)93{94 struct map_info *map = mtd->priv;95 96 if (!map->virt)97 return -EINVAL;98 *virt = map->virt + from;99 if (phys)100 *phys = map->phys + from;101 *retlen = len;102 return 0;103}104 105static int mapram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)106{107 return 0;108}109 110static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)111{112 struct map_info *map = mtd->priv;113 114 map_copy_from(map, buf, from, len);115 *retlen = len;116 return 0;117}118 119static int mapram_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)120{121 struct map_info *map = mtd->priv;122 123 map_copy_to(map, to, buf, len);124 *retlen = len;125 return 0;126}127 128static int mapram_erase (struct mtd_info *mtd, struct erase_info *instr)129{130 /* Yeah, it's inefficient. Who cares? It's faster than a _real_131 flash erase. */132 struct map_info *map = mtd->priv;133 map_word allff;134 unsigned long i;135 136 allff = map_word_ff(map);137 for (i=0; i<instr->len; i += map_bankwidth(map))138 map_write(map, allff, instr->addr + i);139 return 0;140}141 142static void mapram_nop(struct mtd_info *mtd)143{144 /* Nothing to see here */145}146 147static int __init map_ram_init(void)148{149 register_mtd_chip_driver(&mapram_chipdrv);150 return 0;151}152 153static void __exit map_ram_exit(void)154{155 unregister_mtd_chip_driver(&mapram_chipdrv);156}157 158module_init(map_ram_init);159module_exit(map_ram_exit);160 161MODULE_LICENSE("GPL");162MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");163MODULE_DESCRIPTION("MTD chip driver for RAM chips");164