Date:	Fri, 15 Aug 2008 16:37:01 +0800
From:	Bryan Wu <cooloney@...nel.org>
To:	dwmw2@...radead.org
Cc:	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Mike Frysinger <vapier.adi@...il.com>,
	Bryan Wu <cooloney@...nel.org>
Subject: [PATCH 1/1] MTD Maps: initial driver for using gpios to assist in addressing of parallel flash as is on the tinyboards

From: Mike Frysinger <vapier.adi@...il.com>

extend driver to handle arbitrary number of gpios

Signed-off-by: Mike Frysinger <vapier.adi@...il.com>
Signed-off-by: Bryan Wu <cooloney@...nel.org>
---
 drivers/mtd/maps/Kconfig           |    9 +
 drivers/mtd/maps/Makefile          |    1 +
 drivers/mtd/maps/gpio-addr-flash.c |  419 ++++++++++++++++++++++++++++++++++++
 3 files changed, 429 insertions(+), 0 deletions(-)
 create mode 100644 drivers/mtd/maps/gpio-addr-flash.c

diff --git a/drivers/mtd/maps/Kconfig b/drivers/mtd/maps/Kconfig
index 50bb046..76f05ad 100644
--- a/drivers/mtd/maps/Kconfig
+++ b/drivers/mtd/maps/Kconfig
@@ -520,6 +520,15 @@ config MTD_BFIN_ASYNC
 
 	  If compiled as a module, it will be called bfin-async-flash.
 
+config MTD_GPIO_ADDR
+	tristate "GPIO-assisted Flash Chip Support"
+	select MTD_PARTITIONS
+	help
+	  Map driver which allows flashes to be partially physically addressed
+	  and assisted by GPIOs.
+
+	  If compiled as a module, it will be called gpio-addr-flash.
+
 config MTD_UCLINUX
 	tristate "Generic uClinux RAM/ROM filesystem support"
 	depends on MTD_PARTITIONS && MTD_RAM && !MMU
diff --git a/drivers/mtd/maps/Makefile b/drivers/mtd/maps/Makefile
index 6cda6df..fdfaa5e 100644
--- a/drivers/mtd/maps/Makefile
+++ b/drivers/mtd/maps/Makefile
@@ -65,3 +65,4 @@ obj-$(CONFIG_MTD_PLATRAM)	+= plat-ram.o
 obj-$(CONFIG_MTD_OMAP_NOR)	+= omap_nor.o
 obj-$(CONFIG_MTD_INTEL_VR_NOR)	+= intel_vr_nor.o
 obj-$(CONFIG_MTD_BFIN_ASYNC)	+= bfin-async-flash.o
+obj-$(CONFIG_MTD_GPIO_ADDR)	+= gpio-addr-flash.o
diff --git a/drivers/mtd/maps/gpio-addr-flash.c b/drivers/mtd/maps/gpio-addr-flash.c
new file mode 100644
index 0000000..eae74d4
--- /dev/null
+++ b/drivers/mtd/maps/gpio-addr-flash.c
@@ -0,0 +1,419 @@
+/*
+ * drivers/mtd/maps/gpio-addr-flash.c
+ *
+ * Handle the case where a flash device is mostly addressed using physical
+ * line and supplemented by GPIOs.  This way you can hook up say a 8meg flash
+ * to a 2meg memory range and use the GPIOs to select a particular range.
+ *
+ * Copyright 2000 Nicolas Pitre <nico@....org>
+ * Copyright 2005-2008 Analog Devices Inc.
+ *
+ * Enter bugs at http://blackfin.uclinux.org/
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#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/mtd/physmap.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+#include <asm/gpio.h>
+#include <asm/io.h>
+
+#define pr_devinit(fmt, args...) ({ static const __devinitconst char __fmt[] = fmt; printk(__fmt, ## args); })
+
+#define DRIVER_NAME "gpio-addr-flash"
+
+struct async_state {
+	struct mtd_info *mtd;
+	struct map_info map;
+	size_t gpio_count;
+	unsigned *gpio_addrs;
+	unsigned long win_size;
+};
+
+static void gf_set_gpios(struct async_state *state, unsigned long ofs)
+{
+	size_t i;
+	for (i = 0; i < state->gpio_count; ++i)
+		gpio_set_value(state->gpio_addrs[i], !!((ofs / state->win_size) & (1 << i)));
+}
+
+static map_word gf_read(struct map_info *map, unsigned long ofs)
+{
+	struct async_state *state = (struct async_state *)map->map_priv_1;
+	u16 word;
+	map_word test;
+
+	gf_set_gpios(state, ofs);
+
+	word = readw(map->virt + (ofs % state->win_size));
+	test.x[0] = word;
+	return test;
+}
+
+static void gf_copy_from(struct map_info *map, void *to, unsigned long from, ssize_t len)
+{
+	struct async_state *state = (struct async_state *)map->map_priv_1;
+
+	gf_set_gpios(state, from);
+
+	/* BUG if operation crosss the win_size */
+	BUG_ON(!((from + len) % state->win_size <= (from + len)));
+
+	/* operation does not cross the win_size, so one shot it */
+	memcpy_fromio(to, map->virt + (from % state->win_size), len);
+}
+
+static void gf_write(struct map_info *map, map_word d1, unsigned long ofs)
+{
+	struct async_state *state = (struct async_state *)map->map_priv_1;
+	u16 d;
+
+	gf_set_gpios(state, ofs);
+
+	d = d1.x[0];
+	writew(d, map->virt + (ofs % state->win_size));
+}
+
+static void gf_copy_to(struct map_info *map, unsigned long to, const void *from, ssize_t len)
+{
+	struct async_state *state = (struct async_state *)map->map_priv_1;
+
+	gf_set_gpios(state, to);
+
+	/* BUG if operation crosss the win_size */
+	BUG_ON(!((to + len) % state->win_size <= (to + len)));
+
+	/* operation does not cross the win_size, so one shot it */
+	memcpy_toio(map->virt + (to % state->win_size), from, len);
+}
+
+#ifdef CONFIG_MTD_PARTITIONS
+static const char *part_probe_types[] = { "cmdlinepart", "RedBoot", NULL };
+#endif
+
+static int __devinit gpio_flash_probe(struct platform_device *pdev)
+{
+	int ret;
+	size_t i;
+	struct physmap_flash_data *pdata = pdev->dev.platform_data;
+	struct resource *memory = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	struct resource *gpios = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	struct async_state *state;
+
+	state = kzalloc(sizeof(*state) + sizeof(unsigned) * gpios->end, GFP_KERNEL);
+	if (!state)
+		return -ENOMEM;
+
+	state->gpio_count     = gpios->end;
+	state->gpio_addrs     = (void *)(state + 1);
+	state->win_size       = memory->end - memory->start + 1;
+	memcpy(state->gpio_addrs, (void *)gpios->start, sizeof(unsigned) * state->gpio_count);
+
+	state->map.name       = DRIVER_NAME;
+	state->map.read       = gf_read;
+	state->map.copy_from  = gf_copy_from;
+	state->map.write      = gf_write;
+	state->map.copy_to    = gf_copy_to;
+	state->map.bankwidth  = pdata->width;
+	state->map.size       = state->win_size * (1 << state->gpio_count);
+	state->map.virt       = (void __iomem *)memory->start;
+	state->map.phys       = memory->start;
+	state->map.map_priv_1 = (unsigned long)state;
+
+	platform_set_drvdata(pdev, state);
+
+	for (i = 0; i < state->gpio_count; ++i) {
+		if (gpio_request(state->gpio_addrs[i], DRIVER_NAME)) {
+			pr_devinit(KERN_ERR DRIVER_NAME ": Failed to request gpio %d\n", state->gpio_addrs[i]);
+			while (i--)
+				gpio_free(state->gpio_addrs[i]);
+			kfree(state);
+			return -EBUSY;
+		}
+		gpio_direction_output(state->gpio_addrs[i], 0);
+	}
+
+	pr_devinit(KERN_NOTICE DRIVER_NAME ": probing %d-bit flash bus\n", state->map.bankwidth * 8);
+	state->mtd = do_map_probe(memory->name, &state->map);
+	if (!state->mtd) {
+		for (i = 0; i < state->gpio_count; ++i)
+			gpio_free(state->gpio_addrs[i]);
+		kfree(state);
+		return -ENXIO;
+	}
+
+#ifdef CONFIG_MTD_PARTITIONS
+	ret = parse_mtd_partitions(state->mtd, part_probe_types, &pdata->parts, 0);
+	if (ret > 0) {
+		pr_devinit(KERN_NOTICE DRIVER_NAME ": Using commandline partition definition\n");
+		add_mtd_partitions(state->mtd, pdata->parts, ret);
+
+	} else if (pdata->nr_parts) {
+		pr_devinit(KERN_NOTICE DRIVER_NAME ": Using board partition definition\n");
+		add_mtd_partitions(state->mtd, pdata->parts, pdata->nr_parts);
+
+	} else
+#endif
+	{
+		pr_devinit(KERN_NOTICE DRIVER_NAME ": no partition info available, registering whole flash at once\n");
+		add_mtd_device(state->mtd);
+	}
+
+	return 0;
+}
+
+static int __devexit gpio_flash_remove(struct platform_device *pdev)
+{
+	struct async_state *state = platform_get_drvdata(pdev);
+	size_t i;
+	for (i = 0; i < state->gpio_count; ++i)
+		gpio_free(state->gpio_addrs[i]);
+#ifdef CONFIG_MTD_PARTITIONS
+	del_mtd_partitions(state->mtd);
+#endif
+	map_destroy(state->mtd);
+	kfree(state);
+	return 0;
+}
+
+static struct platform_driver gpio_flash_driver = {
+	.probe		= gpio_flash_probe,
+	.remove		= __devexit_p(gpio_flash_remove),
+	.driver		= {
+		.name	= DRIVER_NAME,
+	},
+};
+
+static int __init gpio_flash_init(void)
+{
+	return platform_driver_register(&gpio_flash_driver);
+}
+module_init(gpio_flash_init);
+
+static void __exit gpio_flash_exit(void)
+{
+	platform_driver_unregister(&gpio_flash_driver);
+}
+module_exit(gpio_flash_exit);
+
+MODULE_AUTHOR("Mike Frysinger <vapier@...too.org>");
+MODULE_DESCRIPTION("MTD map driver for flashes addressed physically and with gpios");
+MODULE_LICENSE("GPL");
+/*
+ * drivers/mtd/maps/gpio-addr-flash.c
+ *
+ * Handle the case where a flash device is mostly addressed using physical
+ * line and supplemented by GPIOs.  This way you can hook up say a 8meg flash
+ * to a 2meg memory range and use the GPIOs to select a particular range.
+ *
+ * Copyright 2000 Nicolas Pitre <nico@....org>
+ * Copyright 2005-2008 Analog Devices Inc.
+ *
+ * Enter bugs at http://blackfin.uclinux.org/
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#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/mtd/physmap.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+#include <asm/gpio.h>
+#include <asm/io.h>
+
+#define stamp(fmt, args...) pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args)
+#define stampit() stamp("here i am")
+#define pr_devinit(fmt, args...) ({ static const __devinitconst char __fmt[] = fmt; printk(__fmt, ## args); })
+
+#define DRIVER_NAME "gpio-addr-flash"
+
+struct async_state {
+	struct mtd_info *mtd;
+	struct map_info map;
+	unsigned gpio_addr;
+	unsigned long boundary;
+};
+
+static map_word gf_read(struct map_info *map, unsigned long ofs)
+{
+	struct async_state *state = (struct async_state *)map->map_priv_1;
+	u16 word;
+	map_word test;
+
+	stamp("gpio: %i, ofs = %lx", !!(ofs >= state->boundary), ofs);
+
+	gpio_set_value(state->gpio_addr, !!(ofs >= state->boundary));
+
+	word = readw(map->virt + (ofs % state->boundary));
+
+	test.x[0] = word;
+	return test;
+}
+
+static void gf_copy_from(struct map_info *map, void *to, unsigned long from, ssize_t len)
+{
+	struct async_state *state = (struct async_state *)map->map_priv_1;
+
+	stamp("gpio: %i, to = %p, from = %lx, len = %lx", !!(from >= state->boundary), to, from, len);
+
+	gpio_set_value(state->gpio_addr, !!(from >= state->boundary));
+
+	if ((from + len) % state->boundary <= (from + len)) {
+		/* operation does not cross the boundary, so one shot it */
+		memcpy(to, map->virt + (from % state->boundary), len);
+	} else {
+		/* operation does cross the boundary, so break it up */
+		stamp("two shot");
+		memcpy(to, map->virt + from, state->boundary - from);
+		gpio_set_value(state->gpio_addr, 1);
+		memcpy(to, map->virt + state->boundary, (from + len) % state->boundary);
+	}
+}
+
+static void gf_write(struct map_info *map, map_word d1, unsigned long ofs)
+{
+	struct async_state *state = (struct async_state *)map->map_priv_1;
+	u16 d;
+
+	stamp("gpio: %i, ofs = %lx", !!(ofs >= state->boundary), ofs);
+
+	d = d1.x[0];
+
+	gpio_set_value(state->gpio_addr, !!(ofs >= state->boundary));
+
+	writew(d, map->virt + (ofs % state->boundary));
+}
+
+static void gf_copy_to(struct map_info *map, unsigned long to, const void *from, ssize_t len)
+{
+	struct async_state *state = (struct async_state *)map->map_priv_1;
+
+	stamp("gpio: %i, to = %lx, from = %p, len = %lx", !!(to >= state->boundary), to, from, len);
+
+	gpio_set_value(state->gpio_addr, !!(to >= state->boundary));
+
+	if ((to + len) % state->boundary <= (to + len)) {
+		/* operation does not cross the boundary, so one shot it */
+		memcpy(map->virt + (to % state->boundary), from, len);
+	} else {
+		/* operation does cross the boundary, so break it up */
+		stamp("two shot");
+		memcpy(map->virt + to, from, state->boundary - to);
+		gpio_set_value(state->gpio_addr, 1);
+		memcpy(map->virt + state->boundary, from, (to + len) % state->boundary);
+	}
+}
+
+#ifdef CONFIG_MTD_PARTITIONS
+static const char *part_probe_types[] = { "cmdlinepart", "RedBoot", NULL };
+#endif
+
+static int __devinit gpio_flash_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct physmap_flash_data *pdata = pdev->dev.platform_data;
+	struct resource *memory = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	struct async_state *state;
+
+	state = kzalloc(sizeof(*state), GFP_KERNEL);
+	if (!state)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, state);
+
+	state->map.name       = DRIVER_NAME;
+	state->map.read       = gf_read;
+	state->map.copy_from  = gf_copy_from;
+	state->map.write      = gf_write;
+	state->map.copy_to    = gf_copy_to;
+	state->map.bankwidth  = pdata->width;
+	state->map.size       = (memory->end - memory->start + 1) * 2;
+	state->map.virt       = (void __iomem *)memory->start;
+	state->map.phys       = memory->start;
+	state->map.map_priv_1 = (unsigned long)state;
+	state->gpio_addr      = platform_get_irq(pdev, 0);
+	state->boundary       = memory->end - memory->start + 1;
+
+	if (gpio_request(state->gpio_addr, DRIVER_NAME)) {
+		pr_devinit(KERN_ERR DRIVER_NAME ": Failed to request gpio %d\n", state->gpio_addr);
+		kfree(state);
+		return -EBUSY;
+	}
+	gpio_direction_output(state->gpio_addr, 0);
+
+	pr_devinit(KERN_NOTICE DRIVER_NAME ": probing %d-bit flash bus\n", state->map.bankwidth * 8);
+	state->mtd = do_map_probe(memory->name, &state->map);
+	if (!state->mtd) {
+		gpio_free(state->gpio_addr);
+		kfree(state);
+		return -ENXIO;
+	}
+
+#ifdef CONFIG_MTD_PARTITIONS
+	ret = parse_mtd_partitions(state->mtd, part_probe_types, &pdata->parts, 0);
+	if (ret > 0) {
+		pr_devinit(KERN_NOTICE DRIVER_NAME ": Using commandline partition definition\n");
+		add_mtd_partitions(state->mtd, pdata->parts, ret);
+
+	} else if (pdata->nr_parts) {
+		pr_devinit(KERN_NOTICE DRIVER_NAME ": Using board partition definition\n");
+		add_mtd_partitions(state->mtd, pdata->parts, pdata->nr_parts);
+
+	} else
+#endif
+	{
+		pr_devinit(KERN_NOTICE DRIVER_NAME ": no partition info available, registering whole flash at once\n");
+		add_mtd_device(state->mtd);
+	}
+
+	return 0;
+}
+
+static int __devexit gpio_flash_remove(struct platform_device *pdev)
+{
+	struct async_state *state = platform_get_drvdata(pdev);
+	gpio_free(state->gpio_addr);
+#ifdef CONFIG_MTD_PARTITIONS
+	del_mtd_partitions(state->mtd);
+#endif
+	map_destroy(state->mtd);
+	kfree(state);
+	return 0;
+}
+
+static struct platform_driver gpio_flash_driver = {
+	.probe		= gpio_flash_probe,
+	.remove		= __devexit_p(gpio_flash_remove),
+	.driver		= {
+		.name	= DRIVER_NAME,
+	},
+};
+
+static int __init gpio_flash_init(void)
+{
+	return platform_driver_register(&gpio_flash_driver);
+}
+module_init(gpio_flash_init);
+
+static void __exit gpio_flash_exit(void)
+{
+	platform_driver_unregister(&gpio_flash_driver);
+}
+module_exit(gpio_flash_exit);
+
+MODULE_AUTHOR("Mike Frysinger <vapier@...too.org>");
+MODULE_DESCRIPTION("MTD map driver for flashes addressed physically and with gpios");
+MODULE_LICENSE("GPL");
-- 
1.5.6
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