target/linux/generic/patches-2.6.25/922-gpiommc.patch

   1 --- /dev/null
   2 +++ b/drivers/mmc/host/gpiommc.c
   3 @@ -0,0 +1,605 @@
   4 +/*
   5 + * Driver an MMC/SD card on a bitbanging GPIO SPI bus.
   6 + * This module hooks up the mmc_spi and spi_gpio modules and also
   7 + * provides a configfs interface.
   8 + *
   9 + * Licensed under the GNU/GPL. See COPYING for details.
  10 + */
  11 +
  12 +#include <linux/mmc/gpiommc.h>
  13 +#include <linux/platform_device.h>
  14 +#include <linux/list.h>
  15 +#include <linux/mutex.h>
  16 +#include <linux/spi/spi_gpio.h>
  17 +#include <linux/configfs.h>
  18 +#include <linux/gpio.h>
  19 +#include <asm/atomic.h>
  20 +
  21 +
  22 +#define PFX                            "gpio-mmc: "
  23 +
  24 +
  25 +struct gpiommc_device {
  26 +       struct platform_device *pdev;
  27 +       struct platform_device *spi_pdev;
  28 +       struct spi_board_info boardinfo;
  29 +};
  30 +
  31 +
  32 +MODULE_DESCRIPTION("GPIO based MMC driver");
  33 +MODULE_LICENSE("GPL");
  34 +
  35 +
  36 +static int gpiommc_boardinfo_setup(struct spi_board_info *bi,
  37 +                                  struct spi_master *master,
  38 +                                  void *data)
  39 +{
  40 +       struct gpiommc_device *d = data;
  41 +       struct gpiommc_platform_data *pdata = d->pdev->dev.platform_data;
  42 +
  43 +       /* Bind the SPI master to the MMC-SPI host driver. */
  44 +       strlcpy(bi->modalias, "mmc_spi", sizeof(bi->modalias));
  45 +
  46 +       bi->max_speed_hz = pdata->max_bus_speed;
  47 +       bi->bus_num = master->bus_num;
  48 +       bi->mode = pdata->mode;
  49 +
  50 +       return 0;
  51 +}
  52 +
  53 +static int gpiommc_probe(struct platform_device *pdev)
  54 +{
  55 +       struct gpiommc_platform_data *mmc_pdata = pdev->dev.platform_data;
  56 +       struct spi_gpio_platform_data spi_pdata;
  57 +       struct gpiommc_device *d;
  58 +       int err;
  59 +
  60 +       err = -ENXIO;
  61 +       if (!mmc_pdata)
  62 +               goto error;
  63 +
  64 +#ifdef CONFIG_MMC_SPI_MODULE
  65 +       err = request_module("mmc_spi");
  66 +       if (err) {
  67 +               printk(KERN_WARNING PFX
  68 +                      "Failed to request mmc_spi module.\n");
  69 +       }
  70 +#endif /* CONFIG_MMC_SPI_MODULE */
  71 +
  72 +       /* Allocate the GPIO-MMC device */
  73 +       err = -ENOMEM;
  74 +       d = kzalloc(sizeof(*d), GFP_KERNEL);
  75 +       if (!d)
  76 +               goto error;
  77 +       d->pdev = pdev;
  78 +
  79 +       /* Create the SPI-GPIO device */
  80 +       d->spi_pdev = platform_device_alloc(SPI_GPIO_PLATDEV_NAME,
  81 +                                           spi_gpio_next_id());
  82 +       if (!d->spi_pdev)
  83 +               goto err_free_d;
  84 +
  85 +       memset(&spi_pdata, 0, sizeof(spi_pdata));
  86 +       spi_pdata.pin_clk = mmc_pdata->pins.gpio_clk;
  87 +       spi_pdata.pin_miso = mmc_pdata->pins.gpio_do;
  88 +       spi_pdata.pin_mosi = mmc_pdata->pins.gpio_di;
  89 +       spi_pdata.pin_cs = mmc_pdata->pins.gpio_cs;
  90 +       spi_pdata.cs_activelow = mmc_pdata->pins.cs_activelow;
  91 +       spi_pdata.no_spi_delay = mmc_pdata->no_spi_delay;
  92 +       spi_pdata.boardinfo_setup = gpiommc_boardinfo_setup;
  93 +       spi_pdata.boardinfo_setup_data = d;
  94 +
  95 +       err = platform_device_add_data(d->spi_pdev, &spi_pdata,
  96 +                                      sizeof(spi_pdata));
  97 +       if (err)
  98 +               goto err_free_pdev;
  99 +       err = platform_device_add(d->spi_pdev);
 100 +       if (err)
 101 +               goto err_free_pdata;
 102 +       platform_set_drvdata(pdev, d);
 103 +
 104 +       printk(KERN_INFO PFX "MMC-Card \"%s\" "
 105 +              "attached to GPIO pins di=%u, do=%u, clk=%u, cs=%u\n",
 106 +              mmc_pdata->name, mmc_pdata->pins.gpio_di,
 107 +              mmc_pdata->pins.gpio_do,
 108 +              mmc_pdata->pins.gpio_clk,
 109 +              mmc_pdata->pins.gpio_cs);
 110 +
 111 +       return 0;
 112 +
 113 +err_free_pdata:
 114 +       kfree(d->spi_pdev->dev.platform_data);
 115 +       d->spi_pdev->dev.platform_data = NULL;
 116 +err_free_pdev:
 117 +       platform_device_put(d->spi_pdev);
 118 +err_free_d:
 119 +       kfree(d);
 120 +error:
 121 +       return err;
 122 +}
 123 +
 124 +static int gpiommc_remove(struct platform_device *pdev)
 125 +{
 126 +       struct gpiommc_device *d = platform_get_drvdata(pdev);
 127 +       struct gpiommc_platform_data *pdata = d->pdev->dev.platform_data;
 128 +
 129 +       platform_device_unregister(d->spi_pdev);
 130 +       printk(KERN_INFO PFX "GPIO based MMC-Card \"%s\" removed\n",
 131 +              pdata->name);
 132 +       platform_device_put(d->spi_pdev);
 133 +
 134 +       return 0;
 135 +}
 136 +
 137 +#ifdef CONFIG_GPIOMMC_CONFIGFS
 138 +
 139 +/* A device that was created through configfs */
 140 +struct gpiommc_configfs_device {
 141 +       struct config_item item;
 142 +       /* The platform device, after registration. */
 143 +       struct platform_device *pdev;
 144 +       /* The configuration */
 145 +       struct gpiommc_platform_data pdata;
 146 +};
 147 +
 148 +#define GPIO_INVALID   -1
 149 +
 150 +static inline bool gpiommc_is_registered(struct gpiommc_configfs_device *dev)
 151 +{
 152 +       return (dev->pdev != NULL);
 153 +}
 154 +
 155 +static inline struct gpiommc_configfs_device *ci_to_gpiommc(struct config_item *item)
 156 +{
 157 +       return item ? container_of(item, struct gpiommc_configfs_device, item) : NULL;
 158 +}
 159 +
 160 +static struct configfs_attribute gpiommc_attr_DI = {
 161 +       .ca_owner = THIS_MODULE,
 162 +       .ca_name = "gpio_data_in",
 163 +       .ca_mode = S_IRUGO | S_IWUSR,
 164 +};
 165 +
 166 +static struct configfs_attribute gpiommc_attr_DO = {
 167 +       .ca_owner = THIS_MODULE,
 168 +       .ca_name = "gpio_data_out",
 169 +       .ca_mode = S_IRUGO | S_IWUSR,
 170 +};
 171 +
 172 +static struct configfs_attribute gpiommc_attr_CLK = {
 173 +       .ca_owner = THIS_MODULE,
 174 +       .ca_name = "gpio_clock",
 175 +       .ca_mode = S_IRUGO | S_IWUSR,
 176 +};
 177 +
 178 +static struct configfs_attribute gpiommc_attr_CS = {
 179 +       .ca_owner = THIS_MODULE,
 180 +       .ca_name = "gpio_chipselect",
 181 +       .ca_mode = S_IRUGO | S_IWUSR,
 182 +};
 183 +
 184 +static struct configfs_attribute gpiommc_attr_CS_activelow = {
 185 +       .ca_owner = THIS_MODULE,
 186 +       .ca_name = "gpio_chipselect_activelow",
 187 +       .ca_mode = S_IRUGO | S_IWUSR,
 188 +};
 189 +
 190 +static struct configfs_attribute gpiommc_attr_spimode = {
 191 +       .ca_owner = THIS_MODULE,
 192 +       .ca_name = "spi_mode",
 193 +       .ca_mode = S_IRUGO | S_IWUSR,
 194 +};
 195 +
 196 +static struct configfs_attribute gpiommc_attr_spidelay = {
 197 +       .ca_owner = THIS_MODULE,
 198 +       .ca_name = "spi_delay",
 199 +       .ca_mode = S_IRUGO | S_IWUSR,
 200 +};
 201 +
 202 +static struct configfs_attribute gpiommc_attr_max_bus_speed = {
 203 +       .ca_owner = THIS_MODULE,
 204 +       .ca_name = "max_bus_speed",
 205 +       .ca_mode = S_IRUGO | S_IWUSR,
 206 +};
 207 +
 208 +static struct configfs_attribute gpiommc_attr_register = {
 209 +       .ca_owner = THIS_MODULE,
 210 +       .ca_name = "register",
 211 +       .ca_mode = S_IRUGO | S_IWUSR,
 212 +};
 213 +
 214 +static struct configfs_attribute *gpiommc_config_attrs[] = {
 215 +       &gpiommc_attr_DI,
 216 +       &gpiommc_attr_DO,
 217 +       &gpiommc_attr_CLK,
 218 +       &gpiommc_attr_CS,
 219 +       &gpiommc_attr_CS_activelow,
 220 +       &gpiommc_attr_spimode,
 221 +       &gpiommc_attr_spidelay,
 222 +       &gpiommc_attr_max_bus_speed,
 223 +       &gpiommc_attr_register,
 224 +       NULL,
 225 +};
 226 +
 227 +static ssize_t gpiommc_config_attr_show(struct config_item *item,
 228 +                                       struct configfs_attribute *attr,
 229 +                                       char *page)
 230 +{
 231 +       struct gpiommc_configfs_device *dev = ci_to_gpiommc(item);
 232 +       ssize_t count = 0;
 233 +       unsigned int gpio;
 234 +       int err = 0;
 235 +
 236 +       if (attr == &gpiommc_attr_DI) {
 237 +               gpio = dev->pdata.pins.gpio_di;
 238 +               if (gpio == GPIO_INVALID)
 239 +                       count = snprintf(page, PAGE_SIZE, "not configured\n");
 240 +               else
 241 +                       count = snprintf(page, PAGE_SIZE, "%u\n", gpio);
 242 +               goto out;
 243 +       }
 244 +       if (attr == &gpiommc_attr_DO) {
 245 +               gpio = dev->pdata.pins.gpio_do;
 246 +               if (gpio == GPIO_INVALID)
 247 +                       count = snprintf(page, PAGE_SIZE, "not configured\n");
 248 +               else
 249 +                       count = snprintf(page, PAGE_SIZE, "%u\n", gpio);
 250 +               goto out;
 251 +       }
 252 +       if (attr == &gpiommc_attr_CLK) {
 253 +               gpio = dev->pdata.pins.gpio_clk;
 254 +               if (gpio == GPIO_INVALID)
 255 +                       count = snprintf(page, PAGE_SIZE, "not configured\n");
 256 +               else
 257 +                       count = snprintf(page, PAGE_SIZE, "%u\n", gpio);
 258 +               goto out;
 259 +       }
 260 +       if (attr == &gpiommc_attr_CS) {
 261 +               gpio = dev->pdata.pins.gpio_cs;
 262 +               if (gpio == GPIO_INVALID)
 263 +                       count = snprintf(page, PAGE_SIZE, "not configured\n");
 264 +               else
 265 +                       count = snprintf(page, PAGE_SIZE, "%u\n", gpio);
 266 +               goto out;
 267 +       }
 268 +       if (attr == &gpiommc_attr_CS_activelow) {
 269 +               count = snprintf(page, PAGE_SIZE, "%u\n",
 270 +                                dev->pdata.pins.cs_activelow);
 271 +               goto out;
 272 +       }
 273 +       if (attr == &gpiommc_attr_spimode) {
 274 +               count = snprintf(page, PAGE_SIZE, "%u\n",
 275 +                                dev->pdata.mode);
 276 +               goto out;
 277 +       }
 278 +       if (attr == &gpiommc_attr_spidelay) {
 279 +               count = snprintf(page, PAGE_SIZE, "%u\n",
 280 +                                !dev->pdata.no_spi_delay);
 281 +               goto out;
 282 +       }
 283 +       if (attr == &gpiommc_attr_max_bus_speed) {
 284 +               count = snprintf(page, PAGE_SIZE, "%u\n",
 285 +                                dev->pdata.max_bus_speed);
 286 +               goto out;
 287 +       }
 288 +       if (attr == &gpiommc_attr_register) {
 289 +               count = snprintf(page, PAGE_SIZE, "%u\n",
 290 +                                gpiommc_is_registered(dev));
 291 +               goto out;
 292 +       }
 293 +       WARN_ON(1);
 294 +       err = -ENOSYS;
 295 +out:
 296 +       return err ? err : count;
 297 +}
 298 +
 299 +static int gpiommc_do_register(struct gpiommc_configfs_device *dev,
 300 +                              const char *name)
 301 +{
 302 +       int err;
 303 +
 304 +       if (gpiommc_is_registered(dev))
 305 +               return 0;
 306 +
 307 +       if (!gpio_is_valid(dev->pdata.pins.gpio_di) ||
 308 +           !gpio_is_valid(dev->pdata.pins.gpio_do) ||
 309 +           !gpio_is_valid(dev->pdata.pins.gpio_clk) ||
 310 +           !gpio_is_valid(dev->pdata.pins.gpio_cs)) {
 311 +               printk(KERN_ERR PFX
 312 +                      "configfs: Invalid GPIO pin number(s)\n");
 313 +               return -EINVAL;
 314 +       }
 315 +
 316 +       strlcpy(dev->pdata.name, name,
 317 +               sizeof(dev->pdata.name));
 318 +
 319 +       dev->pdev = platform_device_alloc(GPIOMMC_PLATDEV_NAME,
 320 +                                         gpiommc_next_id());
 321 +       if (!dev->pdev)
 322 +               return -ENOMEM;
 323 +       err = platform_device_add_data(dev->pdev, &dev->pdata,
 324 +                                      sizeof(dev->pdata));
 325 +       if (err) {
 326 +               platform_device_put(dev->pdev);
 327 +               return err;
 328 +       }
 329 +       err = platform_device_add(dev->pdev);
 330 +       if (err) {
 331 +               platform_device_put(dev->pdev);
 332 +               return err;
 333 +       }
 334 +
 335 +       return 0;
 336 +}
 337 +
 338 +static void gpiommc_do_unregister(struct gpiommc_configfs_device *dev)
 339 +{
 340 +       if (!gpiommc_is_registered(dev))
 341 +               return;
 342 +
 343 +       platform_device_unregister(dev->pdev);
 344 +       dev->pdev = NULL;
 345 +}
 346 +
 347 +static ssize_t gpiommc_config_attr_store(struct config_item *item,
 348 +                                        struct configfs_attribute *attr,
 349 +                                        const char *page, size_t count)
 350 +{
 351 +       struct gpiommc_configfs_device *dev = ci_to_gpiommc(item);
 352 +       int err = -EINVAL;
 353 +       unsigned long data;
 354 +
 355 +       if (attr == &gpiommc_attr_register) {
 356 +               err = strict_strtoul(page, 10, &data);
 357 +               if (err)
 358 +                       goto out;
 359 +               err = -EINVAL;
 360 +               if (data == 1)
 361 +                       err = gpiommc_do_register(dev, item->ci_name);
 362 +               if (data == 0) {
 363 +                       gpiommc_do_unregister(dev);
 364 +                       err = 0;
 365 +               }
 366 +               goto out;
 367 +       }
 368 +
 369 +       if (gpiommc_is_registered(dev)) {
 370 +               /* The rest of the config parameters can only be set
 371 +                * as long as the device is not registered, yet. */
 372 +               err = -EBUSY;
 373 +               goto out;
 374 +       }
 375 +
 376 +       if (attr == &gpiommc_attr_DI) {
 377 +               err = strict_strtoul(page, 10, &data);
 378 +               if (err)
 379 +                       goto out;
 380 +               err = -EINVAL;
 381 +               if (!gpio_is_valid(data))
 382 +                       goto out;
 383 +               dev->pdata.pins.gpio_di = data;
 384 +               err = 0;
 385 +               goto out;
 386 +       }
 387 +       if (attr == &gpiommc_attr_DO) {
 388 +               err = strict_strtoul(page, 10, &data);
 389 +               if (err)
 390 +                       goto out;
 391 +               err = -EINVAL;
 392 +               if (!gpio_is_valid(data))
 393 +                       goto out;
 394 +               dev->pdata.pins.gpio_do = data;
 395 +               err = 0;
 396 +               goto out;
 397 +       }
 398 +       if (attr == &gpiommc_attr_CLK) {
 399 +               err = strict_strtoul(page, 10, &data);
 400 +               if (err)
 401 +                       goto out;
 402 +               err = -EINVAL;
 403 +               if (!gpio_is_valid(data))
 404 +                       goto out;
 405 +               dev->pdata.pins.gpio_clk = data;
 406 +               err = 0;
 407 +               goto out;
 408 +       }
 409 +       if (attr == &gpiommc_attr_CS) {
 410 +               err = strict_strtoul(page, 10, &data);
 411 +               if (err)
 412 +                       goto out;
 413 +               err = -EINVAL;
 414 +               if (!gpio_is_valid(data))
 415 +                       goto out;
 416 +               dev->pdata.pins.gpio_cs = data;
 417 +               err = 0;
 418 +               goto out;
 419 +       }
 420 +       if (attr == &gpiommc_attr_CS_activelow) {
 421 +               err = strict_strtoul(page, 10, &data);
 422 +               if (err)
 423 +                       goto out;
 424 +               err = -EINVAL;
 425 +               if (data != 0 && data != 1)
 426 +                       goto out;
 427 +               dev->pdata.pins.cs_activelow = data;
 428 +               err = 0;
 429 +               goto out;
 430 +       }
 431 +       if (attr == &gpiommc_attr_spimode) {
 432 +               err = strict_strtoul(page, 10, &data);
 433 +               if (err)
 434 +                       goto out;
 435 +               err = -EINVAL;
 436 +               switch (data) {
 437 +               case 0:
 438 +                       dev->pdata.mode = SPI_MODE_0;
 439 +                       break;
 440 +               case 1:
 441 +                       dev->pdata.mode = SPI_MODE_1;
 442 +                       break;
 443 +               case 2:
 444 +                       dev->pdata.mode = SPI_MODE_2;
 445 +                       break;
 446 +               case 3:
 447 +                       dev->pdata.mode = SPI_MODE_3;
 448 +                       break;
 449 +               default:
 450 +                       goto out;
 451 +               }
 452 +               err = 0;
 453 +               goto out;
 454 +       }
 455 +       if (attr == &gpiommc_attr_spidelay) {
 456 +               err = strict_strtoul(page, 10, &data);
 457 +               if (err)
 458 +                       goto out;
 459 +               err = -EINVAL;
 460 +               if (data != 0 && data != 1)
 461 +                       goto out;
 462 +               dev->pdata.no_spi_delay = !data;
 463 +               err = 0;
 464 +               goto out;
 465 +       }
 466 +       if (attr == &gpiommc_attr_max_bus_speed) {
 467 +               err = strict_strtoul(page, 10, &data);
 468 +               if (err)
 469 +                       goto out;
 470 +               err = -EINVAL;
 471 +               if (data > UINT_MAX)
 472 +                       goto out;
 473 +               dev->pdata.max_bus_speed = data;
 474 +               err = 0;
 475 +               goto out;
 476 +       }
 477 +       WARN_ON(1);
 478 +       err = -ENOSYS;
 479 +out:
 480 +       return err ? err : count;
 481 +}
 482 +
 483 +static void gpiommc_config_item_release(struct config_item *item)
 484 +{
 485 +       struct gpiommc_configfs_device *dev = ci_to_gpiommc(item);
 486 +
 487 +       kfree(dev);
 488 +}
 489 +
 490 +static struct configfs_item_operations gpiommc_config_item_ops = {
 491 +       .release                = gpiommc_config_item_release,
 492 +       .show_attribute         = gpiommc_config_attr_show,
 493 +       .store_attribute        = gpiommc_config_attr_store,
 494 +};
 495 +
 496 +static struct config_item_type gpiommc_dev_ci_type = {
 497 +       .ct_item_ops    = &gpiommc_config_item_ops,
 498 +       .ct_attrs       = gpiommc_config_attrs,
 499 +       .ct_owner       = THIS_MODULE,
 500 +};
 501 +
 502 +static struct config_item *gpiommc_make_item(struct config_group *group,
 503 +                                            const char *name)
 504 +{
 505 +       struct gpiommc_configfs_device *dev;
 506 +
 507 +       if (strlen(name) > GPIOMMC_MAX_NAMELEN) {
 508 +               printk(KERN_ERR PFX "configfs: device name too long\n");
 509 +               return NULL;
 510 +       }
 511 +
 512 +       dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 513 +       if (!dev)
 514 +               return NULL;
 515 +
 516 +       config_item_init_type_name(&dev->item, name,
 517 +                                  &gpiommc_dev_ci_type);
 518 +
 519 +       /* Assign default configuration */
 520 +       dev->pdata.pins.gpio_di = GPIO_INVALID;
 521 +       dev->pdata.pins.gpio_do = GPIO_INVALID;
 522 +       dev->pdata.pins.gpio_clk = GPIO_INVALID;
 523 +       dev->pdata.pins.gpio_cs = GPIO_INVALID;
 524 +       dev->pdata.pins.cs_activelow = 1;
 525 +       dev->pdata.mode = SPI_MODE_0;
 526 +       dev->pdata.no_spi_delay = 0;
 527 +       dev->pdata.max_bus_speed = 5000000; /* 5 MHz */
 528 +
 529 +       return &(dev->item);
 530 +}
 531 +
 532 +static void gpiommc_drop_item(struct config_group *group,
 533 +                             struct config_item *item)
 534 +{
 535 +       struct gpiommc_configfs_device *dev = ci_to_gpiommc(item);
 536 +
 537 +       gpiommc_do_unregister(dev);
 538 +       kfree(dev);
 539 +}
 540 +
 541 +static struct configfs_group_operations gpiommc_ct_group_ops = {
 542 +       .make_item      = gpiommc_make_item,
 543 +       .drop_item      = gpiommc_drop_item,
 544 +};
 545 +
 546 +static struct config_item_type gpiommc_ci_type = {
 547 +       .ct_group_ops   = &gpiommc_ct_group_ops,
 548 +       .ct_owner       = THIS_MODULE,
 549 +};
 550 +
 551 +static struct configfs_subsystem gpiommc_subsys = {
 552 +       .su_group = {
 553 +               .cg_item = {
 554 +                       .ci_namebuf = GPIOMMC_PLATDEV_NAME,
 555 +                       .ci_type = &gpiommc_ci_type,
 556 +               },
 557 +       },
 558 +       .su_mutex = __MUTEX_INITIALIZER(gpiommc_subsys.su_mutex),
 559 +};
 560 +
 561 +#endif /* CONFIG_GPIOMMC_CONFIGFS */
 562 +
 563 +static struct platform_driver gpiommc_plat_driver = {
 564 +       .probe  = gpiommc_probe,
 565 +       .remove = gpiommc_remove,
 566 +       .driver = {
 567 +               .name   = GPIOMMC_PLATDEV_NAME,
 568 +               .owner  = THIS_MODULE,
 569 +       },
 570 +};
 571 +
 572 +int gpiommc_next_id(void)
 573 +{
 574 +       static atomic_t counter = ATOMIC_INIT(-1);
 575 +
 576 +       return atomic_inc_return(&counter);
 577 +}
 578 +EXPORT_SYMBOL(gpiommc_next_id);
 579 +
 580 +static int __init gpiommc_modinit(void)
 581 +{
 582 +       int err;
 583 +
 584 +       err = platform_driver_register(&gpiommc_plat_driver);
 585 +       if (err)
 586 +               return err;
 587 +
 588 +#ifdef CONFIG_GPIOMMC_CONFIGFS
 589 +       config_group_init(&gpiommc_subsys.su_group);
 590 +       err = configfs_register_subsystem(&gpiommc_subsys);
 591 +       if (err) {
 592 +               platform_driver_unregister(&gpiommc_plat_driver);
 593 +               return err;
 594 +       }
 595 +#endif /* CONFIG_GPIOMMC_CONFIGFS */
 596 +
 597 +       return 0;
 598 +}
 599 +module_init(gpiommc_modinit);
 600 +
 601 +static void __exit gpiommc_modexit(void)
 602 +{
 603 +#ifdef CONFIG_GPIOMMC_CONFIGFS
 604 +       configfs_unregister_subsystem(&gpiommc_subsys);
 605 +#endif
 606 +       platform_driver_unregister(&gpiommc_plat_driver);
 607 +}
 608 +module_exit(gpiommc_modexit);
 609 --- a/drivers/mmc/host/Kconfig
 610 +++ b/drivers/mmc/host/Kconfig
 611 @@ -130,3 +130,27 @@ config MMC_SPI
 612
 613           If unsure, or if your system has no SPI master driver, say N.
 614
 615 +config GPIOMMC
 616 +       tristate "MMC/SD over GPIO-based SPI"
 617 +       depends on MMC && MMC_SPI && SPI_GPIO
 618 +       help
 619 +         This driver hooks up the mmc_spi and spi_gpio modules so that
 620 +         MMC/SD cards can be used on a GPIO based bus by bitbanging
 621 +         the SPI protocol in software.
 622 +
 623 +         This driver provides a configfs interface to dynamically create
 624 +         and destroy GPIO-based MMC/SD card devices. It also provides
 625 +         a platform device interface API.
 626 +         See Documentation/gpiommc.txt for details.
 627 +
 628 +         The module will be called gpiommc.
 629 +
 630 +         If unsure, say N.
 631 +
 632 +config GPIOMMC_CONFIGFS
 633 +       bool
 634 +       depends on GPIOMMC && CONFIGFS_FS
 635 +       default y
 636 +       help
 637 +         This option automatically enables configfs support for gpiommc
 638 +         if configfs is available.
 639 --- a/drivers/mmc/host/Makefile
 640 +++ b/drivers/mmc/host/Makefile
 641 @@ -17,4 +17,4 @@ obj-$(CONFIG_MMC_OMAP)                += omap.o
 642  obj-$(CONFIG_MMC_AT91)         += at91_mci.o
 643  obj-$(CONFIG_MMC_TIFM_SD)      += tifm_sd.o
 644  obj-$(CONFIG_MMC_SPI)          += mmc_spi.o
 645 -
 646 +obj-$(CONFIG_GPIOMMC)          += gpiommc.o
 647 --- /dev/null
 648 +++ b/include/linux/mmc/gpiommc.h
 649 @@ -0,0 +1,69 @@
 650 +/*
 651 + * Device driver for MMC/SD cards driven over a GPIO bus.
 652 + *
 653 + * Licensed under the GNU/GPL version 2.
 654 + */
 655 +#ifndef LINUX_GPIOMMC_H_
 656 +#define LINUX_GPIOMMC_H_
 657 +
 658 +#include <linux/types.h>
 659 +
 660 +
 661 +#define GPIOMMC_MAX_NAMELEN            15
 662 +#define GPIOMMC_MAX_NAMELEN_STR                __stringify(GPIOMMC_MAX_NAMELEN)
 663 +
 664 +/**
 665 + * struct gpiommc_pins - Hardware pin assignments
 666 + *
 667 + * @gpio_di: The GPIO number of the DATA IN pin
 668 + * @gpio_do: The GPIO number of the DATA OUT pin
 669 + * @gpio_clk: The GPIO number of the CLOCK pin
 670 + * @gpio_cs: The GPIO number of the CHIPSELECT pin
 671 + * @cs_activelow: If true, the chip is considered selected if @gpio_cs is low.
 672 + */
 673 +struct gpiommc_pins {
 674 +       unsigned int gpio_di;
 675 +       unsigned int gpio_do;
 676 +       unsigned int gpio_clk;
 677 +       unsigned int gpio_cs;
 678 +       bool cs_activelow;
 679 +};
 680 +
 681 +/**
 682 + * struct gpiommc_platform_data - Platform data for a MMC-over-SPI-GPIO device.
 683 + *
 684 + * @name: The unique name string of the device.
 685 + * @pins: The hardware pin assignments.
 686 + * @mode: The hardware mode. This is either SPI_MODE_0,
 687 + *        SPI_MODE_1, SPI_MODE_2 or SPI_MODE_3. See the SPI documentation.
 688 + * @no_spi_delay: Do not use delays in the lowlevel SPI bitbanging code.
 689 + *                This is not standards compliant, but may be required for some
 690 + *                embedded machines to gain reasonable speed.
 691 + * @max_bus_speed: The maximum speed of the SPI bus, in Hertz.
 692 + */
 693 +struct gpiommc_platform_data {
 694 +       char name[GPIOMMC_MAX_NAMELEN + 1];
 695 +       struct gpiommc_pins pins;
 696 +       u8 mode;
 697 +       bool no_spi_delay;
 698 +       unsigned int max_bus_speed;
 699 +};
 700 +
 701 +/**
 702 + * GPIOMMC_PLATDEV_NAME - The platform device name string.
 703 + *
 704 + * The name string that has to be used for platform_device_alloc
 705 + * when allocating a gpiommc device.
 706 + */
 707 +#define GPIOMMC_PLATDEV_NAME   "gpiommc"
 708 +
 709 +/**
 710 + * gpiommc_next_id - Get another platform device ID number.
 711 + *
 712 + * This returns the next platform device ID number that has to be used
 713 + * for platform_device_alloc. The ID is opaque and should not be used for
 714 + * anything else.
 715 + */
 716 +int gpiommc_next_id(void);
 717 +
 718 +#endif /* LINUX_GPIOMMC_H_ */
 719 --- /dev/null
 720 +++ b/Documentation/gpiommc.txt
 721 @@ -0,0 +1,97 @@
 722 +GPIOMMC - Driver for an MMC/SD card on a bitbanging GPIO SPI bus
 723 +================================================================
 724 +
 725 +The gpiommc module hooks up the mmc_spi and spi_gpio modules for running an
 726 +MMC or SD card on GPIO pins.
 727 +
 728 +Two interfaces for registering a new MMC/SD card device are provided:
 729 +A static platform-device based mechanism and a dynamic configfs based interface.
 730 +
 731 +
 732 +Registering devices via platform-device
 733 +=======================================
 734 +
 735 +The platform-device interface is used for registering MMC/SD devices that are
 736 +part of the hardware platform. This is most useful only for embedded machines
 737 +with MMC/SD devices statically connected to the platform GPIO bus.
 738 +
 739 +The data structures are declared in <linux/mmc/gpiommc.h>.
 740 +
 741 +To register a new device, define an instance of struct gpiommc_platform_data.
 742 +This structure holds any information about how the device is hooked up to the
 743 +GPIO pins and what hardware modes the device supports. See the docbook-style
 744 +documentation in the header file for more information on the struct fields.
 745 +
 746 +Then allocate a new instance of a platform device by doing:
 747 +
 748 +       pdev = platform_device_alloc(GPIOMMC_PLATDEV_NAME, gpiommc_next_id());
 749 +
 750 +This will allocate the platform device data structures and hook it up to the
 751 +gpiommc driver.
 752 +Then add the gpiommc_platform_data to the platform device.
 753 +
 754 +       err = platform_device_add_data(pdev, pdata, sizeof(struct gpiommc_platform_data));
 755 +
 756 +You may free the local instance of struct gpiommc_platform_data now. (So the
 757 +struct may be allocated on the stack, too).
 758 +Now simply register the platform device.
 759 +
 760 +       err = platform_device_add(pdev);
 761 +
 762 +Done. The gpiommc probe routine will be invoked now and you should see a kernel
 763 +log message for the added device.
 764 +
 765 +
 766 +Registering devices via configfs
 767 +================================
 768 +
 769 +MMC/SD cards connected via GPIO often are a pretty dynamic thing, as for example
 770 +selfmade hacks for soldering an MMC/SD card to standard GPIO pins on embedded
 771 +hardware are a common situation.
 772 +So we provide a dynamic interface to conveniently handle adding and removing
 773 +devices from userspace, without the need to recompile the kernel.
 774 +
 775 +The "gpiommc" subdirectory at the configfs mountpoint is used for handling
 776 +the dynamic configuration.
 777 +
 778 +To create a new device, it must first be allocated with mkdir.
 779 +The following command will allocate a device named "my_mmc":
 780 +       mkdir /config/gpiommc/my_mmc
 781 +
 782 +There are several configuration files available in the new
 783 +/config/gpiommc/my_mmc/ directory:
 784 +
 785 +gpio_data_in                   = The SPI data-IN GPIO pin number.
 786 +gpio_data_out                  = The SPI data-OUT GPIO pin number.
 787 +gpio_clock                     = The SPI Clock GPIO pin number.
 788 +gpio_chipselect                        = The SPI Chipselect GPIO pin number.
 789 +gpio_chipselect_activelow      = Boolean. If 0, Chipselect is active-HIGH.
 790 +                                 If 1, Chipselect is active-LOW.
 791 +spi_mode                       = The SPI data mode. Can be 0-3.
 792 +spi_delay                      = Enable all delays in the lowlevel bitbanging.
 793 +max_bus_speed                  = The maximum SPI bus speed. In Hertz.
 794 +
 795 +register                       = Not a configuration parameter.
 796 +                                 Used to register the configured card
 797 +                                 with the kernel.
 798 +
 799 +The device must first get configured and then registered by writing "1" to
 800 +the "register" file.
 801 +The configuration parameters "gpio_data_in", "gpio_data_out", "gpio_clock"
 802 +and "gpio_chipselect" are essential and _must_ be configured before writing
 803 +"1" to the "register" file. The registration will fail, otherwise.
 804 +
 805 +The default values for the other parameters are:
 806 +gpio_chipselect_activelow      = 1             (CS active-LOW)
 807 +spi_mode                       = 0             (SPI_MODE_0)
 808 +spi_delay                      = 1             (enabled)
 809 +max_bus_speed                  = 5000000       (5 Mhz)
 810 +
 811 +Configuration values can not be changed after registration. To unregister
 812 +the device, write a "0" to the "register" file. The configuration can be
 813 +changed again after unregistering.
 814 +
 815 +To completely remove the device, simply rmdir the directory
 816 +(/config/gpiommc/my_mmc in this example).
 817 +There's no need to first unregister the device before removing it. That will
 818 +be done automatically.