mtd/maps: gpio-addr-flash: new driver for GPIO assisted flash addressing (d79c326c) · Commits · e / devices / android_kernel_sony_msm8998

drivers/mtd/maps/Kconfig

+10 −0

Original line number	Diff line number	Diff line
		@@ -484,6 +484,16 @@ 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"
		depends on MTD_COMPLEX_MAPPINGS
		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
		bool "Generic uClinux RAM/ROM filesystem support"
		depends on MTD_PARTITIONS && MTD_RAM=y && !MMU

drivers/mtd/maps/Makefile

+1 −2

Original line number	Diff line number	Diff line
		@@ -58,5 +58,4 @@ 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-$(CONFIG_MTD_RBTX4939) += rbtx4939-flash.o
		obj-$(CONFIG_MTD_VMU) += vmu-flash.o
		obj-$(CONFIG_MTD_GPIO_ADDR) += gpio-addr-flash.o

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

0 → 100644

+311 −0

Original line number	Diff line number	Diff line
		/*
		* 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/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"
		#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);
		}

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

		/**
		* 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)
		{
		int ret;
		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;

		state->gpio_count = gpios->end;
		state->gpio_addrs = (void *)gpios->start;
		state->gpio_values = (void *)(state + 1);
		state->win_size = memory->end - memory->start + 1;
		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 = (void __iomem *)memory->start;
		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;
		}

		#ifdef CONFIG_MTD_PARTITIONS
		ret = parse_mtd_partitions(state->mtd, part_probe_types, &pdata->parts, 0);
		if (ret > 0) {
		pr_devinit(KERN_NOTICE PFX "Using commandline partition definition\n");
		add_mtd_partitions(state->mtd, pdata->parts, ret);
		kfree(pdata->parts);

		} else if (pdata->nr_parts) {
		pr_devinit(KERN_NOTICE PFX "Using board partition definition\n");
		add_mtd_partitions(state->mtd, pdata->parts, pdata->nr_parts);

		} else
		#endif
		{
		pr_devinit(KERN_NOTICE PFX "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 = 0;
		do {
		gpio_free(state->gpio_addrs[i]);
		} while (++i < state->gpio_count);
		#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@gentoo.org>");
		MODULE_DESCRIPTION("MTD map driver for flashes addressed physically and with gpios");
		MODULE_LICENSE("GPL");