// SPDX-License-Identifier: GPL-2.0/* * Common code to handle map devices which are simple RAM * (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/mtd/mtd.h>#include <linux/mtd/map.h>  static int mapram_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);static int mapram_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);static int mapram_erase (struct mtd_info *, struct erase_info *);static void mapram_nop (struct mtd_info *);static struct mtd_info *map_ram_probe(struct map_info *map);static int mapram_point (struct mtd_info *mtd, loff_t from, size_t len,			 size_t *retlen, void **virt, resource_size_t *phys);static int mapram_unpoint(struct mtd_info *mtd, loff_t from, size_t len);  static struct mtd_chip_driver mapram_chipdrv = {	.probe	= map_ram_probe,	.name	= "map_ram",	.module	= THIS_MODULE}; static struct mtd_info *map_ram_probe(struct map_info *map){	struct mtd_info *mtd; 	/* Check the first byte is RAM */#if 0	map_write8(map, 0x55, 0);	if (map_read8(map, 0) != 0x55)		return NULL; 	map_write8(map, 0xAA, 0);	if (map_read8(map, 0) != 0xAA)		return NULL; 	/* Check the last byte is RAM */	map_write8(map, 0x55, map->size-1);	if (map_read8(map, map->size-1) != 0x55)		return NULL; 	map_write8(map, 0xAA, map->size-1);	if (map_read8(map, map->size-1) != 0xAA)		return NULL;#endif	/* OK. It seems to be RAM. */ 	mtd = kzalloc_obj(*mtd);	if (!mtd)		return NULL; 	map->fldrv = &mapram_chipdrv;	mtd->priv = map;	mtd->name = map->name;	mtd->type = MTD_RAM;	mtd->size = map->size;	mtd->_erase = mapram_erase;	mtd->_read = mapram_read;	mtd->_write = mapram_write;	mtd->_panic_write = mapram_write;	mtd->_sync = mapram_nop;	mtd->flags = MTD_CAP_RAM;	mtd->writesize = 1; 	/* Disable direct access when NO_XIP is set */	if (map->phys != NO_XIP) {		mtd->_point = mapram_point;		mtd->_unpoint = mapram_unpoint;	} 	mtd->erasesize = PAGE_SIZE; 	while(mtd->size & (mtd->erasesize - 1))		mtd->erasesize >>= 1; 	__module_get(THIS_MODULE);	return mtd;} static int mapram_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 mapram_unpoint(struct mtd_info *mtd, loff_t from, size_t len){	return 0;} static int mapram_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 int mapram_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf){	struct map_info *map = mtd->priv; 	map_copy_to(map, to, buf, len);	*retlen = len;	return 0;} static int mapram_erase (struct mtd_info *mtd, struct erase_info *instr){	/* Yeah, it's inefficient. Who cares? It's faster than a _real_	   flash erase. */	struct map_info *map = mtd->priv;	map_word allff;	unsigned long i; 	allff = map_word_ff(map);	for (i=0; i<instr->len; i += map_bankwidth(map))		map_write(map, allff, instr->addr + i);	return 0;} static void mapram_nop(struct mtd_info *mtd){	/* Nothing to see here */} static int __init map_ram_init(void){	register_mtd_chip_driver(&mapram_chipdrv);	return 0;} static void __exit map_ram_exit(void){	unregister_mtd_chip_driver(&mapram_chipdrv);} module_init(map_ram_init);module_exit(map_ram_exit); MODULE_LICENSE("GPL");MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");MODULE_DESCRIPTION("MTD chip driver for RAM chips");