mtd: do not use plain 0 as NULL

[deliverable/linux.git] / drivers / mtd / maps / dc21285.c

/*
 * MTD map driver for flash on the DC21285 (the StrongARM-110 companion chip)
 *
 * (C) 2000  Nicolas Pitre <nico@fluxnic.net>
 *
 * This code is GPL
 */
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/slab.h>

#include <linux/mtd/mtd.h>
#include <linux/mtd/map.h>
#include <linux/mtd/partitions.h>

#include <asm/io.h>
#include <asm/hardware/dec21285.h>
#include <asm/mach-types.h>


static struct mtd_info *dc21285_mtd;

#ifdef CONFIG_ARCH_NETWINDER
/*
 * This is really ugly, but it seams to be the only
 * realiable way to do it, as the cpld state machine
 * is unpredictible. So we have a 25us penalty per
 * write access.
 */
static void nw_en_write(void)
{
	unsigned long flags;

	/*
	 * we want to write a bit pattern XXX1 to Xilinx to enable
	 * the write gate, which will be open for about the next 2ms.
	 */
	spin_lock_irqsave(&nw_gpio_lock, flags);
	nw_cpld_modify(CPLD_FLASH_WR_ENABLE, CPLD_FLASH_WR_ENABLE);
	spin_unlock_irqrestore(&nw_gpio_lock, flags);

	/*
	 * let the ISA bus to catch on...
	 */
	udelay(25);
}
#else
#define nw_en_write() do { } while (0)
#endif

static map_word dc21285_read8(struct map_info *map, unsigned long ofs)
{
	map_word val;
	val.x[0] = *(uint8_t*)(map->virt + ofs);
	return val;
}

static map_word dc21285_read16(struct map_info *map, unsigned long ofs)
{
	map_word val;
	val.x[0] = *(uint16_t*)(map->virt + ofs);
	return val;
}

static map_word dc21285_read32(struct map_info *map, unsigned long ofs)
{
	map_word val;
	val.x[0] = *(uint32_t*)(map->virt + ofs);
	return val;
}

static void dc21285_copy_from(struct map_info *map, void *to, unsigned long from, ssize_t len)
{
	memcpy(to, (void*)(map->virt + from), len);
}

static void dc21285_write8(struct map_info *map, const map_word d, unsigned long adr)
{
	if (machine_is_netwinder())
		nw_en_write();
	*CSR_ROMWRITEREG = adr & 3;
	adr &= ~3;
	*(uint8_t*)(map->virt + adr) = d.x[0];
}

static void dc21285_write16(struct map_info *map, const map_word d, unsigned long adr)
{
	if (machine_is_netwinder())
		nw_en_write();
	*CSR_ROMWRITEREG = adr & 3;
	adr &= ~3;
	*(uint16_t*)(map->virt + adr) = d.x[0];
}

static void dc21285_write32(struct map_info *map, const map_word d, unsigned long adr)
{
	if (machine_is_netwinder())
		nw_en_write();
	*(uint32_t*)(map->virt + adr) = d.x[0];
}

static void dc21285_copy_to_32(struct map_info *map, unsigned long to, const void *from, ssize_t len)
{
	while (len > 0) {
		map_word d;
		d.x[0] = *((uint32_t*)from);
		dc21285_write32(map, d, to);
		from += 4;
		to += 4;
		len -= 4;
	}
}

static void dc21285_copy_to_16(struct map_info *map, unsigned long to, const void *from, ssize_t len)
{
	while (len > 0) {
		map_word d;
		d.x[0] = *((uint16_t*)from);
		dc21285_write16(map, d, to);
		from += 2;
		to += 2;
		len -= 2;
	}
}

static void dc21285_copy_to_8(struct map_info *map, unsigned long to, const void *from, ssize_t len)
{
	map_word d;
	d.x[0] = *((uint8_t*)from);
	dc21285_write8(map, d, to);
	from++;
	to++;
	len--;
}

static struct map_info dc21285_map = {
	.name = "DC21285 flash",
	.phys = NO_XIP,
	.size = 16*1024*1024,
	.copy_from = dc21285_copy_from,
};


/* Partition stuff */
static const char *probes[] = { "RedBoot", "cmdlinepart", NULL };

static int __init init_dc21285(void)
{
	/* Determine bankwidth */
	switch (*CSR_SA110_CNTL & (3<<14)) {
		case SA110_CNTL_ROMWIDTH_8:
			dc21285_map.bankwidth = 1;
			dc21285_map.read = dc21285_read8;
			dc21285_map.write = dc21285_write8;
			dc21285_map.copy_to = dc21285_copy_to_8;
			break;
		case SA110_CNTL_ROMWIDTH_16:
			dc21285_map.bankwidth = 2;
			dc21285_map.read = dc21285_read16;
			dc21285_map.write = dc21285_write16;
			dc21285_map.copy_to = dc21285_copy_to_16;
			break;
		case SA110_CNTL_ROMWIDTH_32:
			dc21285_map.bankwidth = 4;
			dc21285_map.read = dc21285_read32;
			dc21285_map.write = dc21285_write32;
			dc21285_map.copy_to = dc21285_copy_to_32;
			break;
		default:
			printk (KERN_ERR "DC21285 flash: undefined bankwidth\n");
			return -ENXIO;
	}
	printk (KERN_NOTICE "DC21285 flash support (%d-bit bankwidth)\n",
		dc21285_map.bankwidth*8);

	/* Let's map the flash area */
	dc21285_map.virt = ioremap(DC21285_FLASH, 16*1024*1024);
	if (!dc21285_map.virt) {
		printk("Failed to ioremap\n");
		return -EIO;
	}

	if (machine_is_ebsa285()) {
		dc21285_mtd = do_map_probe("cfi_probe", &dc21285_map);
	} else {
		dc21285_mtd = do_map_probe("jedec_probe", &dc21285_map);
	}

	if (!dc21285_mtd) {
		iounmap(dc21285_map.virt);
		return -ENXIO;
	}

	dc21285_mtd->owner = THIS_MODULE;

	mtd_device_parse_register(dc21285_mtd, probes, NULL, NULL, 0);

	if(machine_is_ebsa285()) {
		/*
		 * Flash timing is determined with bits 19-16 of the
		 * CSR_SA110_CNTL.  The value is the number of wait cycles, or
		 * 0 for 16 cycles (the default).  Cycles are 20 ns.
		 * Here we use 7 for 140 ns flash chips.
		 */
		/* access time */
		*CSR_SA110_CNTL = ((*CSR_SA110_CNTL & ~0x000f0000) | (7 << 16));
		/* burst time */
		*CSR_SA110_CNTL = ((*CSR_SA110_CNTL & ~0x00f00000) | (7 << 20));
		/* tristate time */
		*CSR_SA110_CNTL = ((*CSR_SA110_CNTL & ~0x0f000000) | (7 << 24));
	}

	return 0;
}

static void __exit cleanup_dc21285(void)
{
	mtd_device_unregister(dc21285_mtd);
	map_destroy(dc21285_mtd);
	iounmap(dc21285_map.virt);
}

module_init(init_dc21285);
module_exit(cleanup_dc21285);


MODULE_LICENSE("GPL");
MODULE_AUTHOR("Nicolas Pitre <nico@fluxnic.net>");
MODULE_DESCRIPTION("MTD map driver for DC21285 boards");