/* * 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, }, }; 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");