drivers/mtd/maps/gpio-addr-flash.c - kernel/windcharger - Git at Google

 /*
  * 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 8MiB flash
  * to a 2MiB memory range and use the GPIOs to select a particular range.
  *
  * Copyright © 2000 Nicolas Pitre <nico@cam.org>
  * Copyright © 2005-2009 Analog Devices Inc.
  *
  * Enter bugs at http://blackfin.uclinux.org/
  *
  * Licensed under the GPL-2 or later.
  */

 #include <linux/gpio.h>
 #include <linux/init.h>
 #include <linux/io.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/slab.h>
 #include <linux/types.h>

 #define pr_devinit(fmt, args...) ({ static const __devinitconst char __fmt[] = fmt; printk(__fmt, ## args); })

 #define DRIVER_NAME "gpio-addr-flash"
 #define PFX DRIVER_NAME ": "

 /**
  * struct async_state - keep GPIO flash state
  *	@mtd:         MTD state for this mapping
  *	@map:         MTD map state for this flash
  *	@gpio_count:  number of GPIOs used to address
  *	@gpio_addrs:  array of GPIOs to twiddle
  *	@gpio_values: cached GPIO values
  *	@win_size:    dedicated memory size (if no GPIOs)
  */
 struct async_state {
 	struct mtd_info *mtd;
 	struct map_info map;
 	size_t gpio_count;
 	unsigned *gpio_addrs;
 	int *gpio_values;
 	unsigned long win_size;
 };
 #define gf_map_info_to_state(mi) ((struct async_state *)(mi)->map_priv_1)

 /**
  * gf_set_gpios() - set GPIO address lines to access specified flash offset
  *	@state: GPIO flash state
  *	@ofs:   desired offset to access
  *
  * Rather than call the GPIO framework every time, cache the last-programmed
  * value.  This speeds up sequential accesses (which are by far the most common
  * type).  We rely on the GPIO framework to treat non-zero value as high so
  * that we don't have to normalize the bits.
  */
 static void gf_set_gpios(struct async_state *state, unsigned long ofs)
 {
 	size_t i = 0;
 	int value;
 	ofs /= state->win_size;
 	do {
 		value = ofs & (1 << i);
 		if (state->gpio_values[i] != value) {
 			gpio_set_value(state->gpio_addrs[i], value);
 			state->gpio_values[i] = value;
 		}
 	} while (++i < state->gpio_count);
 }

 /**
  * gf_read() - read a word at the specified offset
  *	@map: MTD map state
  *	@ofs: desired offset to read
  */
 static map_word gf_read(struct map_info *map, unsigned long ofs)
 {
 	struct async_state *state = gf_map_info_to_state(map);
 	uint16_t word;
 	map_word test;

 	gf_set_gpios(state, ofs);

 	word = readw(map->virt + (ofs % state->win_size));
 	test.x[0] = word;
 	return test;
 }

 /**
  * gf_copy_from() - copy a chunk of data from the flash
  *	@map:  MTD map state
  *	@to:   memory to copy to
  *	@from: flash offset to copy from
  *	@len:  how much to copy
  *
  * We rely on the MTD layer to chunk up copies such that a single request here
  * will not cross a window size.  This allows us to only wiggle the GPIOs once
  * before falling back to a normal memcpy.  Reading the higher layer code shows
  * that this is indeed the case, but add a BUG_ON() to future proof.
  */
 static void gf_copy_from(struct map_info *map, void *to, unsigned long from, ssize_t len)
 {
 	struct async_state *state = gf_map_info_to_state(map);

 	gf_set_gpios(state, from);

 	/* BUG if operation crosses 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);
 }

 /**
  * gf_write() - write a word at the specified offset
  *	@map: MTD map state
  *	@ofs: desired offset to write
  */
 static void gf_write(struct map_info *map, map_word d1, unsigned long ofs)
 {
 	struct async_state *state = gf_map_info_to_state(map);
 	uint16_t d;

 	gf_set_gpios(state, ofs);

 	d = d1.x[0];
 	writew(d, map->virt + (ofs % state->win_size));
 }

 /**
  * gf_copy_to() - copy a chunk of data to the flash
  *	@map:  MTD map state
  *	@to:   flash offset to copy to
  *	@from: memory to copy from
  *	@len:  how much to copy
  *
  * See gf_copy_from() caveat.
  */
 static void gf_copy_to(struct map_info *map, unsigned long to, const void *from, ssize_t len)
 {
 	struct async_state *state = gf_map_info_to_state(map);

 	gf_set_gpios(state, to);

 	/* BUG if operation crosses 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);
 }

 static const char *part_probe_types[] = { "cmdlinepart", "RedBoot", NULL };

 /**
  * gpio_flash_probe() - setup a mapping for a GPIO assisted flash
  *	@pdev: platform device
  *
  * The platform resource layout expected looks something like:
  * struct mtd_partition partitions[] = { ... };
  * struct physmap_flash_data flash_data = { ... };
  * unsigned flash_gpios[] = { GPIO_XX, GPIO_XX, ... };
  * struct resource flash_resource[] = {
  *	{
  *		.name  = "cfi_probe",
  *		.start = 0x20000000,
  *		.end   = 0x201fffff,
  *		.flags = IORESOURCE_MEM,
  *	}, {
  *		.start = (unsigned long)flash_gpios,
  *		.end   = ARRAY_SIZE(flash_gpios),
  *		.flags = IORESOURCE_IRQ,
  *	}
  * };
  * struct platform_device flash_device = {
  *	.name          = "gpio-addr-flash",
  *	.dev           = { .platform_data = &flash_data, },
  *	.num_resources = ARRAY_SIZE(flash_resource),
  *	.resource      = flash_resource,
  *	...
  * };
  */
 static int __devinit gpio_flash_probe(struct platform_device *pdev)
 {
 	size_t i, arr_size;
 	struct physmap_flash_data *pdata;
 	struct resource *memory;
 	struct resource *gpios;
 	struct async_state *state;

 	pdata = pdev->dev.platform_data;
 	memory = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	gpios = platform_get_resource(pdev, IORESOURCE_IRQ, 0);

 	if (!memory || !gpios || !gpios->end)
 		return -EINVAL;

 	arr_size = sizeof(int) * gpios->end;
 	state = kzalloc(sizeof(*state) + arr_size, GFP_KERNEL);
 	if (!state)
 		return -ENOMEM;

 	/*
 	 * We cast start/end to known types in the boards file, so cast
 	 * away their pointer types here to the known types (gpios->xxx).
 	 */
 	state->gpio_count     = gpios->end;
 	state->gpio_addrs     = (void *)(unsigned long)gpios->start;
 	state->gpio_values    = (void *)(state + 1);
 	state->win_size       = resource_size(memory);
 	memset(state->gpio_values, 0xff, arr_size);

 	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       = ioremap_nocache(memory->start, state->map.size);
 	state->map.phys       = NO_XIP;
 	state->map.map_priv_1 = (unsigned long)state;

 	platform_set_drvdata(pdev, state);

 	i = 0;
 	do {
 		if (gpio_request(state->gpio_addrs[i], DRIVER_NAME)) {
 			pr_devinit(KERN_ERR PFX "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);
 	} while (++i < state->gpio_count);

 	pr_devinit(KERN_NOTICE PFX "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;
 	}


 	mtd_device_parse_register(state->mtd, part_probe_types, 0,
 			pdata->parts, pdata->nr_parts);

 	return 0;
 }

 static int __devexit gpio_flash_remove(struct platform_device *pdev)
 {
 	struct async_state *state = platform_get_drvdata(pdev);
 	size_t i = 0;
 	do {
 		gpio_free(state->gpio_addrs[i]);
 	} while (++i < state->gpio_count);
 	mtd_device_unregister(state->mtd);
 	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,
 	},
 };

 module_platform_driver(gpio_flash_driver);

 MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.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 8MiB flash
	* to a 2MiB memory range and use the GPIOs to select a particular range.
	*
	* Copyright © 2000 Nicolas Pitre <nico@cam.org>
	* Copyright © 2005-2009 Analog Devices Inc.
	*
	* Enter bugs at http://blackfin.uclinux.org/
	*
	* Licensed under the GPL-2 or later.
	*/

	#include <linux/gpio.h>
	#include <linux/init.h>
	#include <linux/io.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/slab.h>
	#include <linux/types.h>

	#define pr_devinit(fmt, args...) ({ static const __devinitconst char __fmt[] = fmt; printk(__fmt, ## args); })

	#define DRIVER_NAME "gpio-addr-flash"
	#define PFX DRIVER_NAME ": "

	/**
	* struct async_state - keep GPIO flash state
	* @mtd: MTD state for this mapping
	* @map: MTD map state for this flash
	* @gpio_count: number of GPIOs used to address
	* @gpio_addrs: array of GPIOs to twiddle
	* @gpio_values: cached GPIO values
	* @win_size: dedicated memory size (if no GPIOs)
	*/
	struct async_state {
	struct mtd_info *mtd;
	struct map_info map;
	size_t gpio_count;
	unsigned *gpio_addrs;
	int *gpio_values;
	unsigned long win_size;
	};
	#define gf_map_info_to_state(mi) ((struct async_state *)(mi)->map_priv_1)

	/**
	* gf_set_gpios() - set GPIO address lines to access specified flash offset
	* @state: GPIO flash state
	* @ofs: desired offset to access
	*
	* Rather than call the GPIO framework every time, cache the last-programmed
	* value. This speeds up sequential accesses (which are by far the most common
	* type). We rely on the GPIO framework to treat non-zero value as high so
	* that we don't have to normalize the bits.
	*/
	static void gf_set_gpios(struct async_state *state, unsigned long ofs)
	{
	size_t i = 0;
	int value;
	ofs /= state->win_size;
	do {
	value = ofs & (1 << i);
	if (state->gpio_values[i] != value) {
	gpio_set_value(state->gpio_addrs[i], value);
	state->gpio_values[i] = value;
	}
	} while (++i < state->gpio_count);
	}

	/**
	* gf_read() - read a word at the specified offset
	* @map: MTD map state
	* @ofs: desired offset to read
	*/
	static map_word gf_read(struct map_info *map, unsigned long ofs)
	{
	struct async_state *state = gf_map_info_to_state(map);
	uint16_t word;
	map_word test;

	gf_set_gpios(state, ofs);

	word = readw(map->virt + (ofs % state->win_size));
	test.x[0] = word;
	return test;
	}

	/**
	* gf_copy_from() - copy a chunk of data from the flash
	* @map: MTD map state
	* @to: memory to copy to
	* @from: flash offset to copy from
	* @len: how much to copy
	*
	* We rely on the MTD layer to chunk up copies such that a single request here
	* will not cross a window size. This allows us to only wiggle the GPIOs once
	* before falling back to a normal memcpy. Reading the higher layer code shows
	* that this is indeed the case, but add a BUG_ON() to future proof.
	*/
	static void gf_copy_from(struct map_info map, void to, unsigned long from, ssize_t len)
	{
	struct async_state *state = gf_map_info_to_state(map);

	gf_set_gpios(state, from);

	/* BUG if operation crosses 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);
	}

	/**
	* gf_write() - write a word at the specified offset
	* @map: MTD map state
	* @ofs: desired offset to write
	*/
	static void gf_write(struct map_info *map, map_word d1, unsigned long ofs)
	{
	struct async_state *state = gf_map_info_to_state(map);
	uint16_t d;

	gf_set_gpios(state, ofs);

	d = d1.x[0];
	writew(d, map->virt + (ofs % state->win_size));
	}

	/**
	* gf_copy_to() - copy a chunk of data to the flash
	* @map: MTD map state
	* @to: flash offset to copy to
	* @from: memory to copy from
	* @len: how much to copy
	*
	* See gf_copy_from() caveat.
	*/
	static void gf_copy_to(struct map_info map, unsigned long to, const void from, ssize_t len)
	{
	struct async_state *state = gf_map_info_to_state(map);

	gf_set_gpios(state, to);

	/* BUG if operation crosses 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);
	}

	static const char *part_probe_types[] = { "cmdlinepart", "RedBoot", NULL };

	/**
	* gpio_flash_probe() - setup a mapping for a GPIO assisted flash
	* @pdev: platform device
	*
	* The platform resource layout expected looks something like:
	* struct mtd_partition partitions[] = { ... };
	* struct physmap_flash_data flash_data = { ... };
	* unsigned flash_gpios[] = { GPIO_XX, GPIO_XX, ... };
	* struct resource flash_resource[] = {
	* {
	* .name = "cfi_probe",
	* .start = 0x20000000,
	* .end = 0x201fffff,
	* .flags = IORESOURCE_MEM,
	* }, {
	* .start = (unsigned long)flash_gpios,
	* .end = ARRAY_SIZE(flash_gpios),
	* .flags = IORESOURCE_IRQ,
	* }
	* };
	* struct platform_device flash_device = {
	* .name = "gpio-addr-flash",
	* .dev = { .platform_data = &flash_data, },
	* .num_resources = ARRAY_SIZE(flash_resource),
	* .resource = flash_resource,
	* ...
	* };
	*/
	static int __devinit gpio_flash_probe(struct platform_device *pdev)
	{
	size_t i, arr_size;
	struct physmap_flash_data *pdata;
	struct resource *memory;
	struct resource *gpios;
	struct async_state *state;

	pdata = pdev->dev.platform_data;
	memory = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	gpios = platform_get_resource(pdev, IORESOURCE_IRQ, 0);

	if (!memory \|\| !gpios \|\| !gpios->end)
	return -EINVAL;

	arr_size = sizeof(int) * gpios->end;
	state = kzalloc(sizeof(*state) + arr_size, GFP_KERNEL);
	if (!state)
	return -ENOMEM;

	/*
	* We cast start/end to known types in the boards file, so cast
	* away their pointer types here to the known types (gpios->xxx).
	*/
	state->gpio_count = gpios->end;
	state->gpio_addrs = (void *)(unsigned long)gpios->start;
	state->gpio_values = (void *)(state + 1);
	state->win_size = resource_size(memory);
	memset(state->gpio_values, 0xff, arr_size);

	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 = ioremap_nocache(memory->start, state->map.size);
	state->map.phys = NO_XIP;
	state->map.map_priv_1 = (unsigned long)state;

	platform_set_drvdata(pdev, state);

	i = 0;
	do {
	if (gpio_request(state->gpio_addrs[i], DRIVER_NAME)) {
	pr_devinit(KERN_ERR PFX "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);
	} while (++i < state->gpio_count);

	pr_devinit(KERN_NOTICE PFX "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;
	}


	mtd_device_parse_register(state->mtd, part_probe_types, 0,
	pdata->parts, pdata->nr_parts);

	return 0;
	}

	static int __devexit gpio_flash_remove(struct platform_device *pdev)
	{
	struct async_state *state = platform_get_drvdata(pdev);
	size_t i = 0;
	do {
	gpio_free(state->gpio_addrs[i]);
	} while (++i < state->gpio_count);
	mtd_device_unregister(state->mtd);
	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,
	},
	};

	module_platform_driver(gpio_flash_driver);

	MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
	MODULE_DESCRIPTION("MTD map driver for flashes addressed physically and with gpios");
	MODULE_LICENSE("GPL");