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

   1 /*
   2  * drivers/mtd/maps/gpio-addr-flash.c
   3  *
   4  * Handle the case where a flash device is mostly addressed using physical
   5  * line and supplemented by GPIOs.  This way you can hook up say a 8MiB flash
   6  * to a 2MiB memory range and use the GPIOs to select a particular range.
   7  *
   8  * Copyright © 2000 Nicolas Pitre <nico@cam.org>
   9  * Copyright © 2005-2009 Analog Devices Inc.
  10  *
  11  * Enter bugs at http://blackfin.uclinux.org/
  12  *
  13  * Licensed under the GPL-2 or later.
  14  */
  15
  16 #include <linux/init.h>
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/mtd/mtd.h>
  20 #include <linux/mtd/map.h>
  21 #include <linux/mtd/partitions.h>
  22 #include <linux/mtd/physmap.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/types.h>
  25
  26 #include <asm/gpio.h>
  27 #include <asm/io.h>
  28
  29 #define pr_devinit(fmt, args...) ({ static const __devinitconst char __fmt[] = fmt; printk(__fmt, ## args); })
  30
  31 #define DRIVER_NAME "gpio-addr-flash"
  32 #define PFX DRIVER_NAME ": "
  33
  34 /**
  35  * struct async_state - keep GPIO flash state
  36  *      @mtd:         MTD state for this mapping
  37  *      @map:         MTD map state for this flash
  38  *      @gpio_count:  number of GPIOs used to address
  39  *      @gpio_addrs:  array of GPIOs to twiddle
  40  *      @gpio_values: cached GPIO values
  41  *      @win_size:    dedicated memory size (if no GPIOs)
  42  */
  43 struct async_state {
  44         struct mtd_info *mtd;
  45         struct map_info map;
  46         size_t gpio_count;
  47         unsigned *gpio_addrs;
  48         int *gpio_values;
  49         unsigned long win_size;
  50 };
  51 #define gf_map_info_to_state(mi) ((struct async_state *)(mi)->map_priv_1)
  52
  53 /**
  54  * gf_set_gpios() - set GPIO address lines to access specified flash offset
  55  *      @state: GPIO flash state
  56  *      @ofs:   desired offset to access
  57  *
  58  * Rather than call the GPIO framework every time, cache the last-programmed
  59  * value.  This speeds up sequential accesses (which are by far the most common
  60  * type).  We rely on the GPIO framework to treat non-zero value as high so
  61  * that we don't have to normalize the bits.
  62  */
  63 static void gf_set_gpios(struct async_state *state, unsigned long ofs)
  64 {
  65         size_t i = 0;
  66         int value;
  67         ofs /= state->win_size;
  68         do {
  69                 value = ofs & (1 << i);
  70                 if (state->gpio_values[i] != value) {
  71                         gpio_set_value(state->gpio_addrs[i], value);
  72                         state->gpio_values[i] = value;
  73                 }
  74         } while (++i < state->gpio_count);
  75 }
  76
  77 /**
  78  * gf_read() - read a word at the specified offset
  79  *      @map: MTD map state
  80  *      @ofs: desired offset to read
  81  */
  82 static map_word gf_read(struct map_info *map, unsigned long ofs)
  83 {
  84         struct async_state *state = gf_map_info_to_state(map);
  85         uint16_t word;
  86         map_word test;
  87
  88         gf_set_gpios(state, ofs);
  89
  90         word = readw(map->virt + (ofs % state->win_size));
  91         test.x[0] = word;
  92         return test;
  93 }
  94
  95 /**
  96  * gf_copy_from() - copy a chunk of data from the flash
  97  *      @map:  MTD map state
  98  *      @to:   memory to copy to
  99  *      @from: flash offset to copy from
 100  *      @len:  how much to copy
 101  *
 102  * We rely on the MTD layer to chunk up copies such that a single request here
 103  * will not cross a window size.  This allows us to only wiggle the GPIOs once
 104  * before falling back to a normal memcpy.  Reading the higher layer code shows
 105  * that this is indeed the case, but add a BUG_ON() to future proof.
 106  */
 107 static void gf_copy_from(struct map_info *map, void *to, unsigned long from, ssize_t len)
 108 {
 109         struct async_state *state = gf_map_info_to_state(map);
 110
 111         gf_set_gpios(state, from);
 112
 113         /* BUG if operation crosses the win_size */
 114         BUG_ON(!((from + len) % state->win_size <= (from + len)));
 115
 116         /* operation does not cross the win_size, so one shot it */
 117         memcpy_fromio(to, map->virt + (from % state->win_size), len);
 118 }
 119
 120 /**
 121  * gf_write() - write a word at the specified offset
 122  *      @map: MTD map state
 123  *      @ofs: desired offset to write
 124  */
 125 static void gf_write(struct map_info *map, map_word d1, unsigned long ofs)
 126 {
 127         struct async_state *state = gf_map_info_to_state(map);
 128         uint16_t d;
 129
 130         gf_set_gpios(state, ofs);
 131
 132         d = d1.x[0];
 133         writew(d, map->virt + (ofs % state->win_size));
 134 }
 135
 136 /**
 137  * gf_copy_to() - copy a chunk of data to the flash
 138  *      @map:  MTD map state
 139  *      @to:   flash offset to copy to
 140  *      @from: memory to copy from
 141  *      @len:  how much to copy
 142  *
 143  * See gf_copy_from() caveat.
 144  */
 145 static void gf_copy_to(struct map_info *map, unsigned long to, const void *from, ssize_t len)
 146 {
 147         struct async_state *state = gf_map_info_to_state(map);
 148
 149         gf_set_gpios(state, to);
 150
 151         /* BUG if operation crosses the win_size */
 152         BUG_ON(!((to + len) % state->win_size <= (to + len)));
 153
 154         /* operation does not cross the win_size, so one shot it */
 155         memcpy_toio(map->virt + (to % state->win_size), from, len);
 156 }
 157
 158 #ifdef CONFIG_MTD_PARTITIONS
 159 static const char *part_probe_types[] = { "cmdlinepart", "RedBoot", NULL };
 160 #endif
 161
 162 /**
 163  * gpio_flash_probe() - setup a mapping for a GPIO assisted flash
 164  *      @pdev: platform device
 165  *
 166  * The platform resource layout expected looks something like:
 167  * struct mtd_partition partitions[] = { ... };
 168  * struct physmap_flash_data flash_data = { ... };
 169  * unsigned flash_gpios[] = { GPIO_XX, GPIO_XX, ... };
 170  * struct resource flash_resource[] = {
 171  *      {
 172  *              .name  = "cfi_probe",
 173  *              .start = 0x20000000,
 174  *              .end   = 0x201fffff,
 175  *              .flags = IORESOURCE_MEM,
 176  *      }, {
 177  *              .start = (unsigned long)flash_gpios,
 178  *              .end   = ARRAY_SIZE(flash_gpios),
 179  *              .flags = IORESOURCE_IRQ,
 180  *      }
 181  * };
 182  * struct platform_device flash_device = {
 183  *      .name          = "gpio-addr-flash",
 184  *      .dev           = { .platform_data = &flash_data, },
 185  *      .num_resources = ARRAY_SIZE(flash_resource),
 186  *      .resource      = flash_resource,
 187  *      ...
 188  * };
 189  */
 190 static int __devinit gpio_flash_probe(struct platform_device *pdev)
 191 {
 192         int ret;
 193         size_t i, arr_size;
 194         struct physmap_flash_data *pdata;
 195         struct resource *memory;
 196         struct resource *gpios;
 197         struct async_state *state;
 198
 199         pdata = pdev->dev.platform_data;
 200         memory = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 201         gpios = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 202
 203         if (!memory || !gpios || !gpios->end)
 204                 return -EINVAL;
 205
 206         arr_size = sizeof(int) * gpios->end;
 207         state = kzalloc(sizeof(*state) + arr_size, GFP_KERNEL);
 208         if (!state)
 209                 return -ENOMEM;
 210
 211         state->gpio_count     = gpios->end;
 212         state->gpio_addrs     = (void *)gpios->start;
 213         state->gpio_values    = (void *)(state + 1);
 214         state->win_size       = memory->end - memory->start + 1;
 215         memset(state->gpio_values, 0xff, arr_size);
 216
 217         state->map.name       = DRIVER_NAME;
 218         state->map.read       = gf_read;
 219         state->map.copy_from  = gf_copy_from;
 220         state->map.write      = gf_write;
 221         state->map.copy_to    = gf_copy_to;
 222         state->map.bankwidth  = pdata->width;
 223         state->map.size       = state->win_size * (1 << state->gpio_count);
 224         state->map.virt       = (void __iomem *)memory->start;
 225         state->map.phys       = NO_XIP;
 226         state->map.map_priv_1 = (unsigned long)state;
 227
 228         platform_set_drvdata(pdev, state);
 229
 230         i = 0;
 231         do {
 232                 if (gpio_request(state->gpio_addrs[i], DRIVER_NAME)) {
 233                         pr_devinit(KERN_ERR PFX "failed to request gpio %d\n",
 234                                 state->gpio_addrs[i]);
 235                         while (i--)
 236                                 gpio_free(state->gpio_addrs[i]);
 237                         kfree(state);
 238                         return -EBUSY;
 239                 }
 240                 gpio_direction_output(state->gpio_addrs[i], 0);
 241         } while (++i < state->gpio_count);
 242
 243         pr_devinit(KERN_NOTICE PFX "probing %d-bit flash bus\n",
 244                 state->map.bankwidth * 8);
 245         state->mtd = do_map_probe(memory->name, &state->map);
 246         if (!state->mtd) {
 247                 for (i = 0; i < state->gpio_count; ++i)
 248                         gpio_free(state->gpio_addrs[i]);
 249                 kfree(state);
 250                 return -ENXIO;
 251         }
 252
 253 #ifdef CONFIG_MTD_PARTITIONS
 254         ret = parse_mtd_partitions(state->mtd, part_probe_types, &pdata->parts, 0);
 255         if (ret > 0) {
 256                 pr_devinit(KERN_NOTICE PFX "Using commandline partition definition\n");
 257                 add_mtd_partitions(state->mtd, pdata->parts, ret);
 258                 kfree(pdata->parts);
 259
 260         } else if (pdata->nr_parts) {
 261                 pr_devinit(KERN_NOTICE PFX "Using board partition definition\n");
 262                 add_mtd_partitions(state->mtd, pdata->parts, pdata->nr_parts);
 263
 264         } else
 265 #endif
 266         {
 267                 pr_devinit(KERN_NOTICE PFX "no partition info available, registering whole flash at once\n");
 268                 add_mtd_device(state->mtd);
 269         }
 270
 271         return 0;
 272 }
 273
 274 static int __devexit gpio_flash_remove(struct platform_device *pdev)
 275 {
 276         struct async_state *state = platform_get_drvdata(pdev);
 277         size_t i = 0;
 278         do {
 279                 gpio_free(state->gpio_addrs[i]);
 280         } while (++i < state->gpio_count);
 281 #ifdef CONFIG_MTD_PARTITIONS
 282         del_mtd_partitions(state->mtd);
 283 #endif
 284         map_destroy(state->mtd);
 285         kfree(state);
 286         return 0;
 287 }
 288
 289 static struct platform_driver gpio_flash_driver = {
 290         .probe          = gpio_flash_probe,
 291         .remove         = __devexit_p(gpio_flash_remove),
 292         .driver         = {
 293                 .name   = DRIVER_NAME,
 294         },
 295 };
 296
 297 static int __init gpio_flash_init(void)
 298 {
 299         return platform_driver_register(&gpio_flash_driver);
 300 }
 301 module_init(gpio_flash_init);
 302
 303 static void __exit gpio_flash_exit(void)
 304 {
 305         platform_driver_unregister(&gpio_flash_driver);
 306 }
 307 module_exit(gpio_flash_exit);
 308
 309 MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
 310 MODULE_DESCRIPTION("MTD map driver for flashes addressed physically and with gpios");
 311 MODULE_LICENSE("GPL");