mtd: NOR flash driver for OMAP-L137/AM17x

OMAP-L137/AM17x has limited number of dedicated EMIFA
address pins, enough to interface directly to an SDRAM.
If a device such as an asynchronous flash needs to be
attached to the EMIFA, then either GPIO pins or a chip
select may be used to control the flash device's upper
address lines.

This patch adds support for the NOR flash on the OMAP-L137/
AM17x user interface daughter board using the latch-addr-flash
MTD mapping driver which allows flashes to be partially
physically addressed. The upper address lines are set by
a board specific code which is a separate patch.

Signed-off-by: David Griego <[e-mail]>
Signed-off-by: Aleksey Makarov <[e-mail]>
Signed-off-by: Sergei Shtylyov <[e-mail]>
Signed-off-by: Savinay Dharmappa <[e-mail]>
Signed-off-by: Artem Bityutskiy <[e-mail]>
Signed-off-by: David Woodhouse <[e-mail]>

drivers/mtd/maps/Kconfig

···
 
 	  When built as a module, it will be called pismo.ko
 
+config MTD_LATCH_ADDR
+        tristate "Latch-assisted Flash Chip Support"
+        depends on MTD_COMPLEX_MAPPINGS
+        help
+          Map driver which allows flashes to be partially physically addressed
+          and have the upper address lines set by a board specific code.
+
+          If compiled as a module, it will be called latch-addr-flash.
+
 endmenu

drivers/mtd/maps/Makefile

···
 obj-$(CONFIG_MTD_VMU)		+= vmu-flash.o
 obj-$(CONFIG_MTD_GPIO_ADDR)	+= gpio-addr-flash.o
 obj-$(CONFIG_MTD_BCM963XX)	+= bcm963xx-flash.o
+obj-$(CONFIG_MTD_LATCH_ADDR)	+= latch-addr-flash.o

drivers/mtd/maps/latch-addr-flash.c

···
+/*
+ * Interface for NOR flash driver whose high address lines are latched
+ *
+ * Copyright © 2000 Nicolas Pitre <[e-mail]>
+ * Copyright © 2005-2008 Analog Devices Inc.
+ * Copyright © 2008 MontaVista Software, Inc. <[e-mail]>
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2. This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/map.h>
+#include <linux/mtd/partitions.h>
+#include <linux/platform_device.h>
+#include <linux/mtd/latch-addr-flash.h>
+#include <linux/slab.h>
+
+#define DRIVER_NAME "latch-addr-flash"
+
+struct latch_addr_flash_info {
+	struct mtd_info		*mtd;
+	struct map_info		map;
+	struct resource		*res;
+
+	void			(*set_window)(unsigned long offset, void *data);
+	void			*data;
+
+	/* cache; could be found out of res */
+	unsigned long		win_mask;
+
+	int			nr_parts;
+	struct mtd_partition	*parts;
+
+	spinlock_t		lock;
+};
+
+static map_word lf_read(struct map_info *map, unsigned long ofs)
+{
+	struct latch_addr_flash_info *info;
+	map_word datum;
+
+	info = (struct latch_addr_flash_info *)map->map_priv_1;
+
+	spin_lock(&info->lock);
+
+	info->set_window(ofs, info->data);
+	datum = inline_map_read(map, info->win_mask & ofs);
+
+	spin_unlock(&info->lock);
+
+	return datum;
+}
+
+static void lf_write(struct map_info *map, map_word datum, unsigned long ofs)
+{
+	struct latch_addr_flash_info *info;
+
+	info = (struct latch_addr_flash_info *)map->map_priv_1;
+
+	spin_lock(&info->lock);
+
+	info->set_window(ofs, info->data);
+	inline_map_write(map, datum, info->win_mask & ofs);
+
+	spin_unlock(&info->lock);
+}
+
+static void lf_copy_from(struct map_info *map, void *to,
+		unsigned long from, ssize_t len)
+{
+	struct latch_addr_flash_info *info =
+		(struct latch_addr_flash_info *) map->map_priv_1;
+	unsigned n;
+
+	while (len > 0) {
+		n = info->win_mask + 1 - (from & info->win_mask);
+		if (n > len)
+			n = len;
+
+		spin_lock(&info->lock);
+
+		info->set_window(from, info->data);
+		memcpy_fromio(to, map->virt + (from & info->win_mask), n);
+
+		spin_unlock(&info->lock);
+
+		to += n;
+		from += n;
+		len -= n;
+	}
+}
+
+static char *rom_probe_types[] = { "cfi_probe", NULL };
+
+static char *part_probe_types[] = { "cmdlinepart", NULL };
+
+static int latch_addr_flash_remove(struct platform_device *dev)
+{
+	struct latch_addr_flash_info *info;
+	struct latch_addr_flash_data *latch_addr_data;
+
+	info = platform_get_drvdata(dev);
+	if (info == NULL)
+		return 0;
+	platform_set_drvdata(dev, NULL);
+
+	latch_addr_data = dev->dev.platform_data;
+
+	if (info->mtd != NULL) {
+		if (mtd_has_partitions()) {
+			if (info->nr_parts) {
+				del_mtd_partitions(info->mtd);
+				kfree(info->parts);
+			} else if (latch_addr_data->nr_parts) {
+				del_mtd_partitions(info->mtd);
+			} else {
+				del_mtd_device(info->mtd);
+			}
+		} else {
+			del_mtd_device(info->mtd);
+		}
+		map_destroy(info->mtd);
+	}
+
+	if (info->map.virt != NULL)
+		iounmap(info->map.virt);
+
+	if (info->res != NULL)
+		release_mem_region(info->res->start, resource_size(info->res));
+
+	kfree(info);
+
+	if (latch_addr_data->done)
+		latch_addr_data->done(latch_addr_data->data);
+
+	return 0;
+}
+
+static int __devinit latch_addr_flash_probe(struct platform_device *dev)
+{
+	struct latch_addr_flash_data *latch_addr_data;
+	struct latch_addr_flash_info *info;
+	resource_size_t win_base = dev->resource->start;
+	resource_size_t win_size = resource_size(dev->resource);
+	char **probe_type;
+	int chipsel;
+	int err;
+
+	latch_addr_data = dev->dev.platform_data;
+	if (latch_addr_data == NULL)
+		return -ENODEV;
+
+	pr_notice("latch-addr platform flash device: %#llx byte "
+		  "window at %#.8llx\n",
+		  (unsigned long long)win_size, (unsigned long long)win_base);
+
+	chipsel = dev->id;
+
+	if (latch_addr_data->init) {
+		err = latch_addr_data->init(latch_addr_data->data, chipsel);
+		if (err != 0)
+			return err;
+	}
+
+	info = kzalloc(sizeof(struct latch_addr_flash_info), GFP_KERNEL);
+	if (info == NULL) {
+		err = -ENOMEM;
+		goto done;
+	}
+
+	platform_set_drvdata(dev, info);
+
+	info->res = request_mem_region(win_base, win_size, DRIVER_NAME);
+	if (info->res == NULL) {
+		dev_err(&dev->dev, "Could not reserve memory region\n");
+		err = -EBUSY;
+		goto free_info;
+	}
+
+	info->map.name		= DRIVER_NAME;
+	info->map.size		= latch_addr_data->size;
+	info->map.bankwidth	= latch_addr_data->width;
+
+	info->map.phys		= NO_XIP;
+	info->map.virt		= ioremap(win_base, win_size);
+	if (!info->map.virt) {
+		err = -ENOMEM;
+		goto free_res;
+	}
+
+	info->map.map_priv_1	= (unsigned long)info;
+
+	info->map.read		= lf_read;
+	info->map.copy_from	= lf_copy_from;
+	info->map.write		= lf_write;
+	info->set_window	= latch_addr_data->set_window;
+	info->data		= latch_addr_data->data;
+	info->win_mask		= win_size - 1;
+
+	spin_lock_init(&info->lock);
+
+	for (probe_type = rom_probe_types; !info->mtd && *probe_type;
+		probe_type++)
+		info->mtd = do_map_probe(*probe_type, &info->map);
+
+	if (info->mtd == NULL) {
+		dev_err(&dev->dev, "map_probe failed\n");
+		err = -ENODEV;
+		goto iounmap;
+	}
+	info->mtd->owner = THIS_MODULE;
+
+	if (mtd_has_partitions()) {
+
+		err = parse_mtd_partitions(info->mtd,
+					   (const char **)part_probe_types,
+					   &info->parts, 0);
+		if (err > 0) {
+			add_mtd_partitions(info->mtd, info->parts, err);
+			return 0;
+		}
+		if (latch_addr_data->nr_parts) {
+			pr_notice("Using latch-addr-flash partition information\n");
+			add_mtd_partitions(info->mtd, latch_addr_data->parts,
+					latch_addr_data->nr_parts);
+			return 0;
+		}
+	}
+	add_mtd_device(info->mtd);
+	return 0;
+
+iounmap:
+	iounmap(info->map.virt);
+free_res:
+	release_mem_region(info->res->start, resource_size(info->res));
+free_info:
+	kfree(info);
+done:
+	if (latch_addr_data->done)
+		latch_addr_data->done(latch_addr_data->data);
+	return err;
+}
+
+static struct platform_driver latch_addr_flash_driver = {
+	.probe		= latch_addr_flash_probe,
+	.remove		= __devexit_p(latch_addr_flash_remove),
+	.driver		= {
+		.name	= DRIVER_NAME,
+	},
+};
+
+static int __init latch_addr_flash_init(void)
+{
+	return platform_driver_register(&latch_addr_flash_driver);
+}
+module_init(latch_addr_flash_init);
+
+static void __exit latch_addr_flash_exit(void)
+{
+	platform_driver_unregister(&latch_addr_flash_driver);
+}
+module_exit(latch_addr_flash_exit);
+
+MODULE_AUTHOR("David Griego <[e-mail]>");
+MODULE_DESCRIPTION("MTD map driver for flashes addressed physically with upper "
+		"address lines being set board specifically");
+MODULE_LICENSE("GPL v2");

include/linux/mtd/latch-addr-flash.h

···
+/*
+ * Interface for NOR flash driver whose high address lines are latched
+ *
+ * Copyright © 2008 MontaVista Software, Inc. <[e-mail]>
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2. This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ */
+#ifndef __LATCH_ADDR_FLASH__
+#define __LATCH_ADDR_FLASH__
+
+struct map_info;
+struct mtd_partition;
+
+struct latch_addr_flash_data {
+	unsigned int		width;
+	unsigned int		size;
+
+	int			(*init)(void *data, int cs);
+	void			(*done)(void *data);
+	void			(*set_window)(unsigned long offset, void *data);
+	void			*data;
+
+	unsigned int		nr_parts;
+	struct mtd_partition	*parts;
+};
+
+#endif