drivers/mtd/maps/tsunami_flash.c

// SPDX-License-Identifier: GPL-2.0
/*
 * tsunami_flash.c
 *
 * flash chip on alpha ds10...
 */
#include <asm/io.h>
#include <asm/core_tsunami.h>
#include <linux/init.h>
#include <linux/mtd/map.h>
#include <linux/mtd/mtd.h>

#define FLASH_ENABLE_PORT 0x00C00001
#define FLASH_ENABLE_BYTE 0x01
#define FLASH_DISABLE_BYTE 0x00

#define MAX_TIG_FLASH_SIZE (12*1024*1024)
static inline map_word tsunami_flash_read8(struct map_info *map, unsigned long offset)
{
	map_word val;
	val.x[0] = tsunami_tig_readb(offset);
	return val;
}

static void tsunami_flash_write8(struct map_info *map, map_word value, unsigned long offset)
{
	tsunami_tig_writeb(value.x[0], offset);
}

static void tsunami_flash_copy_from(
	struct map_info *map, void *addr, unsigned long offset, ssize_t len)
{
	unsigned char *dest;
	dest = addr;
	while(len && (offset < MAX_TIG_FLASH_SIZE)) {
		*dest = tsunami_tig_readb(offset);
		offset++;
		dest++;
		len--;
	}
}

static void tsunami_flash_copy_to(
	struct map_info *map, unsigned long offset,
	const void *addr, ssize_t len)
{
	const unsigned char *src;
	src = addr;
	while(len && (offset < MAX_TIG_FLASH_SIZE)) {
		tsunami_tig_writeb(*src, offset);
		offset++;
		src++;
		len--;
	}
}

/*
 * Deliberately don't provide operations wider than 8 bits.  I don't
 * have then and it scares me to think how you could mess up if
 * you tried to use them.   Buswidth is correctly so I'm safe.
 */
static struct map_info tsunami_flash_map = {
	.name = "flash chip on the Tsunami TIG bus",
	.size = MAX_TIG_FLASH_SIZE,
	.phys = NO_XIP,
	.bankwidth = 1,
	.read = tsunami_flash_read8,
	.copy_from = tsunami_flash_copy_from,
	.write = tsunami_flash_write8,
	.copy_to = tsunami_flash_copy_to,
};

static struct mtd_info *tsunami_flash_mtd;

static void __exit  cleanup_tsunami_flash(void)
{
	struct mtd_info *mtd;
	mtd = tsunami_flash_mtd;
	if (mtd) {
		mtd_device_unregister(mtd);
		map_destroy(mtd);
	}
	tsunami_flash_mtd = 0;
}

static const char * const rom_probe_types[] = {
	"cfi_probe", "jedec_probe", "map_rom", NULL };

static int __init init_tsunami_flash(void)
{
	const char * const *type;

	tsunami_tig_writeb(FLASH_ENABLE_BYTE, FLASH_ENABLE_PORT);

	tsunami_flash_mtd = 0;
	type = rom_probe_types;
	for(; !tsunami_flash_mtd && *type; type++) {
		tsunami_flash_mtd = do_map_probe(*type, &tsunami_flash_map);
	}
	if (tsunami_flash_mtd) {
		tsunami_flash_mtd->owner = THIS_MODULE;
		mtd_device_register(tsunami_flash_mtd, NULL, 0);
		return 0;
	}
	return -ENXIO;
}

module_init(init_tsunami_flash);
module_exit(cleanup_tsunami_flash);