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/gpio.h>
  17 #include <linux/io.h>
  18 #include <linux/kernel.h>
  19 #include <linux/module.h>
  20 #include <linux/mtd/mtd.h>
  21 #include <linux/mtd/map.h>
  22 #include <linux/mtd/partitions.h>
  23 #include <linux/mtd/physmap.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/slab.h>
  26 #include <linux/types.h>
  27
  28 #define pr_devinit(fmt, args...) \
  29         ({ static const 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  * The "from" region may straddle more than one window, so toggle the GPIOs for
 103  * each window region before reading its data.
 104  */
 105 static void gf_copy_from(struct map_info *map, void *to, unsigned long from, ssize_t len)
 106 {
 107         struct async_state *state = gf_map_info_to_state(map);
 108
 109         int this_len;
 110
 111         while (len) {
 112                 if ((from % state->win_size) + len > state->win_size)
 113                         this_len = state->win_size - (from % state->win_size);
 114                 else
 115                         this_len = len;
 116
 117                 gf_set_gpios(state, from);
 118                 memcpy_fromio(to, map->virt + (from % state->win_size),
 119                          this_len);
 120                 len -= this_len;
 121                 from += this_len;
 122                 to += this_len;
 123         }
 124 }
 125
 126 /**
 127  * gf_write() - write a word at the specified offset
 128  *      @map: MTD map state
 129  *      @ofs: desired offset to write
 130  */
 131 static void gf_write(struct map_info *map, map_word d1, unsigned long ofs)
 132 {
 133         struct async_state *state = gf_map_info_to_state(map);
 134         uint16_t d;
 135
 136         gf_set_gpios(state, ofs);
 137
 138         d = d1.x[0];
 139         writew(d, map->virt + (ofs % state->win_size));
 140 }
 141
 142 /**
 143  * gf_copy_to() - copy a chunk of data to the flash
 144  *      @map:  MTD map state
 145  *      @to:   flash offset to copy to
 146  *      @from: memory to copy from
 147  *      @len:  how much to copy
 148  *
 149  * See gf_copy_from() caveat.
 150  */
 151 static void gf_copy_to(struct map_info *map, unsigned long to,
 152                        const void *from, ssize_t len)
 153 {
 154         struct async_state *state = gf_map_info_to_state(map);
 155
 156         int this_len;
 157
 158         while (len) {
 159                 if ((to % state->win_size) + len > state->win_size)
 160                         this_len = state->win_size - (to % state->win_size);
 161                 else
 162                         this_len = len;
 163
 164                 gf_set_gpios(state, to);
 165                 memcpy_toio(map->virt + (to % state->win_size), from, len);
 166
 167                 len -= this_len;
 168                 to += this_len;
 169                 from += this_len;
 170         }
 171 }
 172
 173 static const char * const part_probe_types[] = {
 174         "cmdlinepart", "RedBoot", NULL };
 175
 176 /**
 177  * gpio_flash_probe() - setup a mapping for a GPIO assisted flash
 178  *      @pdev: platform device
 179  *
 180  * The platform resource layout expected looks something like:
 181  * struct mtd_partition partitions[] = { ... };
 182  * struct physmap_flash_data flash_data = { ... };
 183  * unsigned flash_gpios[] = { GPIO_XX, GPIO_XX, ... };
 184  * struct resource flash_resource[] = {
 185  *      {
 186  *              .name  = "cfi_probe",
 187  *              .start = 0x20000000,
 188  *              .end   = 0x201fffff,
 189  *              .flags = IORESOURCE_MEM,
 190  *      }, {
 191  *              .start = (unsigned long)flash_gpios,
 192  *              .end   = ARRAY_SIZE(flash_gpios),
 193  *              .flags = IORESOURCE_IRQ,
 194  *      }
 195  * };
 196  * struct platform_device flash_device = {
 197  *      .name          = "gpio-addr-flash",
 198  *      .dev           = { .platform_data = &flash_data, },
 199  *      .num_resources = ARRAY_SIZE(flash_resource),
 200  *      .resource      = flash_resource,
 201  *      ...
 202  * };
 203  */
 204 static int gpio_flash_probe(struct platform_device *pdev)
 205 {
 206         size_t i, arr_size;
 207         struct physmap_flash_data *pdata;
 208         struct resource *memory;
 209         struct resource *gpios;
 210         struct async_state *state;
 211
 212         pdata = dev_get_platdata(&pdev->dev);
 213         memory = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 214         gpios = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 215
 216         if (!memory || !gpios || !gpios->end)
 217                 return -EINVAL;
 218
 219         arr_size = sizeof(int) * gpios->end;
 220         state = kzalloc(sizeof(*state) + arr_size, GFP_KERNEL);
 221         if (!state)
 222                 return -ENOMEM;
 223
 224         /*
 225          * We cast start/end to known types in the boards file, so cast
 226          * away their pointer types here to the known types (gpios->xxx).
 227          */
 228         state->gpio_count     = gpios->end;
 229         state->gpio_addrs     = (void *)(unsigned long)gpios->start;
 230         state->gpio_values    = (void *)(state + 1);
 231         state->win_size       = resource_size(memory);
 232         memset(state->gpio_values, 0xff, arr_size);
 233
 234         state->map.name       = DRIVER_NAME;
 235         state->map.read       = gf_read;
 236         state->map.copy_from  = gf_copy_from;
 237         state->map.write      = gf_write;
 238         state->map.copy_to    = gf_copy_to;
 239         state->map.bankwidth  = pdata->width;
 240         state->map.size       = state->win_size * (1 << state->gpio_count);
 241         state->map.virt       = ioremap_nocache(memory->start, state->map.size);
 242         state->map.phys       = NO_XIP;
 243         state->map.map_priv_1 = (unsigned long)state;
 244
 245         platform_set_drvdata(pdev, state);
 246
 247         i = 0;
 248         do {
 249                 if (gpio_request(state->gpio_addrs[i], DRIVER_NAME)) {
 250                         pr_devinit(KERN_ERR PFX "failed to request gpio %d\n",
 251                                 state->gpio_addrs[i]);
 252                         while (i--)
 253                                 gpio_free(state->gpio_addrs[i]);
 254                         kfree(state);
 255                         return -EBUSY;
 256                 }
 257                 gpio_direction_output(state->gpio_addrs[i], 0);
 258         } while (++i < state->gpio_count);
 259
 260         pr_devinit(KERN_NOTICE PFX "probing %d-bit flash bus\n",
 261                 state->map.bankwidth * 8);
 262         state->mtd = do_map_probe(memory->name, &state->map);
 263         if (!state->mtd) {
 264                 for (i = 0; i < state->gpio_count; ++i)
 265                         gpio_free(state->gpio_addrs[i]);
 266                 kfree(state);
 267                 return -ENXIO;
 268         }
 269         state->mtd->dev.parent = &pdev->dev;
 270
 271         mtd_device_parse_register(state->mtd, part_probe_types, NULL,
 272                                   pdata->parts, pdata->nr_parts);
 273
 274         return 0;
 275 }
 276
 277 static int gpio_flash_remove(struct platform_device *pdev)
 278 {
 279         struct async_state *state = platform_get_drvdata(pdev);
 280         size_t i = 0;
 281         do {
 282                 gpio_free(state->gpio_addrs[i]);
 283         } while (++i < state->gpio_count);
 284         mtd_device_unregister(state->mtd);
 285         map_destroy(state->mtd);
 286         kfree(state);
 287         return 0;
 288 }
 289
 290 static struct platform_driver gpio_flash_driver = {
 291         .probe          = gpio_flash_probe,
 292         .remove         = gpio_flash_remove,
 293         .driver         = {
 294                 .name   = DRIVER_NAME,
 295         },
 296 };
 297
 298 module_platform_driver(gpio_flash_driver);
 299
 300 MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
 301 MODULE_DESCRIPTION("MTD map driver for flashes addressed physically and with gpios");
 302 MODULE_LICENSE("GPL");