--- /dev/null
+/*
+ * 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/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 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
+ *
+ * The "from" region may straddle more than one window, so toggle the GPIOs for
+ * each window region before reading its data.
+ */
+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);
+
+ int this_len;
+
+ while (len) {
+ if ((from % state->win_size) + len > state->win_size)
+ this_len = state->win_size - (from % state->win_size);
+ else
+ this_len = len;
+
+ gf_set_gpios(state, from);
+ memcpy_fromio(to, map->virt + (from % state->win_size),
+ this_len);
+ len -= this_len;
+ from += this_len;
+ to += this_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);
+
+ int this_len;
+
+ while (len) {
+ if ((to % state->win_size) + len > state->win_size)
+ this_len = state->win_size - (to % state->win_size);
+ else
+ this_len = len;
+
+ gf_set_gpios(state, to);
+ memcpy_toio(map->virt + (to % state->win_size), from, len);
+
+ len -= this_len;
+ to += this_len;
+ from += this_len;
+ }
+}
+
+static const char * const 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 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 = dev_get_platdata(&pdev->dev);
+ 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, NULL,
+ pdata->parts, pdata->nr_parts);
+
+ return 0;
+}
+
+static int 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 = 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");
Code Review / kvmfornfv.git / blobdiff