306 lines
8.1 KiB
C
306 lines
8.1 KiB
C
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/*
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* drivers/mtd/maps/gpio-addr-flash.c
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*
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* Handle the case where a flash device is mostly addressed using physical
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* line and supplemented by GPIOs. This way you can hook up say a 8MiB flash
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* to a 2MiB memory range and use the GPIOs to select a particular range.
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*
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* Copyright © 2000 Nicolas Pitre <nico@cam.org>
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* Copyright © 2005-2009 Analog Devices Inc.
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*
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* Enter bugs at http://blackfin.uclinux.org/
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*
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* Licensed under the GPL-2 or later.
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*/
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#include <linux/gpio.h>
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#include <linux/io.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/mtd/mtd.h>
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#include <linux/mtd/map.h>
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#include <linux/mtd/partitions.h>
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#include <linux/mtd/physmap.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#define pr_devinit(fmt, args...) \
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({ static const char __fmt[] = fmt; printk(__fmt, ## args); })
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#define DRIVER_NAME "gpio-addr-flash"
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#define PFX DRIVER_NAME ": "
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/**
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* struct async_state - keep GPIO flash state
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* @mtd: MTD state for this mapping
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* @map: MTD map state for this flash
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* @gpio_count: number of GPIOs used to address
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* @gpio_addrs: array of GPIOs to twiddle
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* @gpio_values: cached GPIO values
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* @win_size: dedicated memory size (if no GPIOs)
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*/
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struct async_state {
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struct mtd_info *mtd;
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struct map_info map;
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size_t gpio_count;
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unsigned *gpio_addrs;
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int *gpio_values;
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unsigned long win_size;
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};
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#define gf_map_info_to_state(mi) ((struct async_state *)(mi)->map_priv_1)
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/**
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* gf_set_gpios() - set GPIO address lines to access specified flash offset
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* @state: GPIO flash state
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* @ofs: desired offset to access
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*
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* Rather than call the GPIO framework every time, cache the last-programmed
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* value. This speeds up sequential accesses (which are by far the most common
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* type). We rely on the GPIO framework to treat non-zero value as high so
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* that we don't have to normalize the bits.
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*/
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static void gf_set_gpios(struct async_state *state, unsigned long ofs)
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{
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size_t i = 0;
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int value;
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ofs /= state->win_size;
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do {
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value = ofs & (1 << i);
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if (state->gpio_values[i] != value) {
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gpio_set_value(state->gpio_addrs[i], value);
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state->gpio_values[i] = value;
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}
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} while (++i < state->gpio_count);
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}
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/**
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* gf_read() - read a word at the specified offset
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* @map: MTD map state
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* @ofs: desired offset to read
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*/
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static map_word gf_read(struct map_info *map, unsigned long ofs)
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{
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struct async_state *state = gf_map_info_to_state(map);
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uint16_t word;
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map_word test;
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gf_set_gpios(state, ofs);
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word = readw(map->virt + (ofs % state->win_size));
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test.x[0] = word;
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return test;
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}
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/**
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* gf_copy_from() - copy a chunk of data from the flash
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* @map: MTD map state
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* @to: memory to copy to
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* @from: flash offset to copy from
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* @len: how much to copy
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*
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* The "from" region may straddle more than one window, so toggle the GPIOs for
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* each window region before reading its data.
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*/
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static void gf_copy_from(struct map_info *map, void *to, unsigned long from, ssize_t len)
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{
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struct async_state *state = gf_map_info_to_state(map);
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int this_len;
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while (len) {
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if ((from % state->win_size) + len > state->win_size)
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this_len = state->win_size - (from % state->win_size);
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else
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this_len = len;
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gf_set_gpios(state, from);
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memcpy_fromio(to, map->virt + (from % state->win_size),
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this_len);
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len -= this_len;
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from += this_len;
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to += this_len;
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}
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}
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/**
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* gf_write() - write a word at the specified offset
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* @map: MTD map state
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* @ofs: desired offset to write
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*/
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static void gf_write(struct map_info *map, map_word d1, unsigned long ofs)
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{
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struct async_state *state = gf_map_info_to_state(map);
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uint16_t d;
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gf_set_gpios(state, ofs);
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d = d1.x[0];
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writew(d, map->virt + (ofs % state->win_size));
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}
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/**
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* gf_copy_to() - copy a chunk of data to the flash
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* @map: MTD map state
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* @to: flash offset to copy to
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* @from: memory to copy from
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* @len: how much to copy
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*
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* See gf_copy_from() caveat.
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*/
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static void gf_copy_to(struct map_info *map, unsigned long to,
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const void *from, ssize_t len)
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{
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struct async_state *state = gf_map_info_to_state(map);
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int this_len;
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while (len) {
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if ((to % state->win_size) + len > state->win_size)
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this_len = state->win_size - (to % state->win_size);
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else
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this_len = len;
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gf_set_gpios(state, to);
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memcpy_toio(map->virt + (to % state->win_size), from, len);
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len -= this_len;
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to += this_len;
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from += this_len;
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}
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}
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static const char * const part_probe_types[] = {
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"cmdlinepart", "RedBoot", NULL };
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/**
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* gpio_flash_probe() - setup a mapping for a GPIO assisted flash
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* @pdev: platform device
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*
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* The platform resource layout expected looks something like:
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* struct mtd_partition partitions[] = { ... };
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* struct physmap_flash_data flash_data = { ... };
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* unsigned flash_gpios[] = { GPIO_XX, GPIO_XX, ... };
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* struct resource flash_resource[] = {
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* {
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* .name = "cfi_probe",
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* .start = 0x20000000,
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* .end = 0x201fffff,
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* .flags = IORESOURCE_MEM,
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* }, {
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* .start = (unsigned long)flash_gpios,
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* .end = ARRAY_SIZE(flash_gpios),
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* .flags = IORESOURCE_IRQ,
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* }
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* };
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* struct platform_device flash_device = {
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* .name = "gpio-addr-flash",
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* .dev = { .platform_data = &flash_data, },
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* .num_resources = ARRAY_SIZE(flash_resource),
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* .resource = flash_resource,
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* ...
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* };
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*/
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static int gpio_flash_probe(struct platform_device *pdev)
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{
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size_t i, arr_size;
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struct physmap_flash_data *pdata;
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struct resource *memory;
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struct resource *gpios;
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struct async_state *state;
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pdata = dev_get_platdata(&pdev->dev);
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memory = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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gpios = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
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if (!memory || !gpios || !gpios->end)
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return -EINVAL;
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arr_size = sizeof(int) * gpios->end;
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state = kzalloc(sizeof(*state) + arr_size, GFP_KERNEL);
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if (!state)
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return -ENOMEM;
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/*
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* We cast start/end to known types in the boards file, so cast
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* away their pointer types here to the known types (gpios->xxx).
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*/
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state->gpio_count = gpios->end;
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state->gpio_addrs = (void *)(unsigned long)gpios->start;
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state->gpio_values = (void *)(state + 1);
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state->win_size = resource_size(memory);
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memset(state->gpio_values, 0xff, arr_size);
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state->map.name = DRIVER_NAME;
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state->map.read = gf_read;
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state->map.copy_from = gf_copy_from;
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state->map.write = gf_write;
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state->map.copy_to = gf_copy_to;
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state->map.bankwidth = pdata->width;
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state->map.size = state->win_size * (1 << state->gpio_count);
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state->map.virt = ioremap_nocache(memory->start, state->win_size);
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if (!state->map.virt)
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return -ENOMEM;
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state->map.phys = NO_XIP;
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state->map.map_priv_1 = (unsigned long)state;
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platform_set_drvdata(pdev, state);
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i = 0;
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do {
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if (gpio_request(state->gpio_addrs[i], DRIVER_NAME)) {
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pr_devinit(KERN_ERR PFX "failed to request gpio %d\n",
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state->gpio_addrs[i]);
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while (i--)
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gpio_free(state->gpio_addrs[i]);
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kfree(state);
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return -EBUSY;
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}
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gpio_direction_output(state->gpio_addrs[i], 0);
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} while (++i < state->gpio_count);
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pr_devinit(KERN_NOTICE PFX "probing %d-bit flash bus\n",
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state->map.bankwidth * 8);
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state->mtd = do_map_probe(memory->name, &state->map);
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if (!state->mtd) {
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for (i = 0; i < state->gpio_count; ++i)
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gpio_free(state->gpio_addrs[i]);
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kfree(state);
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return -ENXIO;
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}
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state->mtd->dev.parent = &pdev->dev;
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mtd_device_parse_register(state->mtd, part_probe_types, NULL,
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pdata->parts, pdata->nr_parts);
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return 0;
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}
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static int gpio_flash_remove(struct platform_device *pdev)
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{
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struct async_state *state = platform_get_drvdata(pdev);
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size_t i = 0;
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do {
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gpio_free(state->gpio_addrs[i]);
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} while (++i < state->gpio_count);
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mtd_device_unregister(state->mtd);
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map_destroy(state->mtd);
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kfree(state);
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return 0;
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}
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static struct platform_driver gpio_flash_driver = {
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.probe = gpio_flash_probe,
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.remove = gpio_flash_remove,
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.driver = {
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.name = DRIVER_NAME,
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},
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};
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module_platform_driver(gpio_flash_driver);
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MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
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MODULE_DESCRIPTION("MTD map driver for flashes addressed physically and with gpios");
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MODULE_LICENSE("GPL");
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