drivers/mmc/core/host.c

   1 /*
   2  *  linux/drivers/mmc/core/host.c
   3  *
   4  *  Copyright (C) 2003 Russell King, All Rights Reserved.
   5  *  Copyright (C) 2007-2008 Pierre Ossman
   6  *  Copyright (C) 2010 Linus Walleij
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  *  MMC host class device management
  13  */
  14
  15 #include <linux/device.h>
  16 #include <linux/err.h>
  17 #include <linux/idr.h>
  18 #include <linux/of.h>
  19 #include <linux/of_gpio.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/export.h>
  22 #include <linux/leds.h>
  23 #include <linux/slab.h>
  24 #include <linux/suspend.h>
  25
  26 #include <linux/mmc/host.h>
  27 #include <linux/mmc/card.h>
  28 #include <linux/mmc/slot-gpio.h>
  29
  30 #include "core.h"
  31 #include "host.h"
  32 #include "slot-gpio.h"
  33 #include "pwrseq.h"
  34
  35 #define cls_dev_to_mmc_host(d)  container_of(d, struct mmc_host, class_dev)
  36
  37 static DEFINE_IDR(mmc_host_idr);
  38 static DEFINE_SPINLOCK(mmc_host_lock);
  39
  40 static void mmc_host_classdev_release(struct device *dev)
  41 {
  42         struct mmc_host *host = cls_dev_to_mmc_host(dev);
  43         spin_lock(&mmc_host_lock);
  44         idr_remove(&mmc_host_idr, host->index);
  45         spin_unlock(&mmc_host_lock);
  46         kfree(host);
  47 }
  48
  49 static struct class mmc_host_class = {
  50         .name           = "mmc_host",
  51         .dev_release    = mmc_host_classdev_release,
  52 };
  53
  54 int mmc_register_host_class(void)
  55 {
  56         return class_register(&mmc_host_class);
  57 }
  58
  59 void mmc_unregister_host_class(void)
  60 {
  61         class_unregister(&mmc_host_class);
  62 }
  63
  64 #ifdef CONFIG_MMC_CLKGATE
  65 static ssize_t clkgate_delay_show(struct device *dev,
  66                 struct device_attribute *attr, char *buf)
  67 {
  68         struct mmc_host *host = cls_dev_to_mmc_host(dev);
  69         return snprintf(buf, PAGE_SIZE, "%lu\n", host->clkgate_delay);
  70 }
  71
  72 static ssize_t clkgate_delay_store(struct device *dev,
  73                 struct device_attribute *attr, const char *buf, size_t count)
  74 {
  75         struct mmc_host *host = cls_dev_to_mmc_host(dev);
  76         unsigned long flags, value;
  77
  78         if (kstrtoul(buf, 0, &value))
  79                 return -EINVAL;
  80
  81         spin_lock_irqsave(&host->clk_lock, flags);
  82         host->clkgate_delay = value;
  83         spin_unlock_irqrestore(&host->clk_lock, flags);
  84         return count;
  85 }
  86
  87 /*
  88  * Enabling clock gating will make the core call out to the host
  89  * once up and once down when it performs a request or card operation
  90  * intermingled in any fashion. The driver will see this through
  91  * set_ios() operations with ios.clock field set to 0 to gate (disable)
  92  * the block clock, and to the old frequency to enable it again.
  93  */
  94 static void mmc_host_clk_gate_delayed(struct mmc_host *host)
  95 {
  96         unsigned long tick_ns;
  97         unsigned long freq = host->ios.clock;
  98         unsigned long flags;
  99
 100         if (!freq) {
 101                 pr_debug("%s: frequency set to 0 in disable function, "
 102                          "this means the clock is already disabled.\n",
 103                          mmc_hostname(host));
 104                 return;
 105         }
 106         /*
 107          * New requests may have appeared while we were scheduling,
 108          * then there is no reason to delay the check before
 109          * clk_disable().
 110          */
 111         spin_lock_irqsave(&host->clk_lock, flags);
 112
 113         /*
 114          * Delay n bus cycles (at least 8 from MMC spec) before attempting
 115          * to disable the MCI block clock. The reference count may have
 116          * gone up again after this delay due to rescheduling!
 117          */
 118         if (!host->clk_requests) {
 119                 spin_unlock_irqrestore(&host->clk_lock, flags);
 120                 tick_ns = DIV_ROUND_UP(1000000000, freq);
 121                 ndelay(host->clk_delay * tick_ns);
 122         } else {
 123                 /* New users appeared while waiting for this work */
 124                 spin_unlock_irqrestore(&host->clk_lock, flags);
 125                 return;
 126         }
 127         mutex_lock(&host->clk_gate_mutex);
 128         spin_lock_irqsave(&host->clk_lock, flags);
 129         if (!host->clk_requests) {
 130                 spin_unlock_irqrestore(&host->clk_lock, flags);
 131                 /* This will set host->ios.clock to 0 */
 132                 mmc_gate_clock(host);
 133                 spin_lock_irqsave(&host->clk_lock, flags);
 134                 pr_debug("%s: gated MCI clock\n", mmc_hostname(host));
 135         }
 136         spin_unlock_irqrestore(&host->clk_lock, flags);
 137         mutex_unlock(&host->clk_gate_mutex);
 138 }
 139
 140 /*
 141  * Internal work. Work to disable the clock at some later point.
 142  */
 143 static void mmc_host_clk_gate_work(struct work_struct *work)
 144 {
 145         struct mmc_host *host = container_of(work, struct mmc_host,
 146                                               clk_gate_work.work);
 147
 148         mmc_host_clk_gate_delayed(host);
 149 }
 150
 151 /**
 152  *      mmc_host_clk_hold - ungate hardware MCI clocks
 153  *      @host: host to ungate.
 154  *
 155  *      Makes sure the host ios.clock is restored to a non-zero value
 156  *      past this call. Increase clock reference count and ungate clock
 157  *      if we're the first user.
 158  */
 159 void mmc_host_clk_hold(struct mmc_host *host)
 160 {
 161         unsigned long flags;
 162
 163         /* cancel any clock gating work scheduled by mmc_host_clk_release() */
 164         cancel_delayed_work_sync(&host->clk_gate_work);
 165         mutex_lock(&host->clk_gate_mutex);
 166         spin_lock_irqsave(&host->clk_lock, flags);
 167         if (host->clk_gated) {
 168                 spin_unlock_irqrestore(&host->clk_lock, flags);
 169                 mmc_ungate_clock(host);
 170                 spin_lock_irqsave(&host->clk_lock, flags);
 171                 pr_debug("%s: ungated MCI clock\n", mmc_hostname(host));
 172         }
 173         host->clk_requests++;
 174         spin_unlock_irqrestore(&host->clk_lock, flags);
 175         mutex_unlock(&host->clk_gate_mutex);
 176 }
 177
 178 /**
 179  *      mmc_host_may_gate_card - check if this card may be gated
 180  *      @card: card to check.
 181  */
 182 static bool mmc_host_may_gate_card(struct mmc_card *card)
 183 {
 184         /* If there is no card we may gate it */
 185         if (!card)
 186                 return true;
 187         /*
 188          * Don't gate SDIO cards! These need to be clocked at all times
 189          * since they may be independent systems generating interrupts
 190          * and other events. The clock requests counter from the core will
 191          * go down to zero since the core does not need it, but we will not
 192          * gate the clock, because there is somebody out there that may still
 193          * be using it.
 194          */
 195         return !(card->quirks & MMC_QUIRK_BROKEN_CLK_GATING);
 196 }
 197
 198 /**
 199  *      mmc_host_clk_release - gate off hardware MCI clocks
 200  *      @host: host to gate.
 201  *
 202  *      Calls the host driver with ios.clock set to zero as often as possible
 203  *      in order to gate off hardware MCI clocks. Decrease clock reference
 204  *      count and schedule disabling of clock.
 205  */
 206 void mmc_host_clk_release(struct mmc_host *host)
 207 {
 208         unsigned long flags;
 209
 210         spin_lock_irqsave(&host->clk_lock, flags);
 211         host->clk_requests--;
 212         if (mmc_host_may_gate_card(host->card) &&
 213             !host->clk_requests)
 214                 schedule_delayed_work(&host->clk_gate_work,
 215                                       msecs_to_jiffies(host->clkgate_delay));
 216         spin_unlock_irqrestore(&host->clk_lock, flags);
 217 }
 218
 219 /**
 220  *      mmc_host_clk_rate - get current clock frequency setting
 221  *      @host: host to get the clock frequency for.
 222  *
 223  *      Returns current clock frequency regardless of gating.
 224  */
 225 unsigned int mmc_host_clk_rate(struct mmc_host *host)
 226 {
 227         unsigned long freq;
 228         unsigned long flags;
 229
 230         spin_lock_irqsave(&host->clk_lock, flags);
 231         if (host->clk_gated)
 232                 freq = host->clk_old;
 233         else
 234                 freq = host->ios.clock;
 235         spin_unlock_irqrestore(&host->clk_lock, flags);
 236         return freq;
 237 }
 238
 239 /**
 240  *      mmc_host_clk_init - set up clock gating code
 241  *      @host: host with potential clock to control
 242  */
 243 static inline void mmc_host_clk_init(struct mmc_host *host)
 244 {
 245         host->clk_requests = 0;
 246         /* Hold MCI clock for 8 cycles by default */
 247         host->clk_delay = 8;
 248         /*
 249          * Default clock gating delay is 0ms to avoid wasting power.
 250          * This value can be tuned by writing into sysfs entry.
 251          */
 252         host->clkgate_delay = 0;
 253         host->clk_gated = false;
 254         INIT_DELAYED_WORK(&host->clk_gate_work, mmc_host_clk_gate_work);
 255         spin_lock_init(&host->clk_lock);
 256         mutex_init(&host->clk_gate_mutex);
 257 }
 258
 259 /**
 260  *      mmc_host_clk_exit - shut down clock gating code
 261  *      @host: host with potential clock to control
 262  */
 263 static inline void mmc_host_clk_exit(struct mmc_host *host)
 264 {
 265         /*
 266          * Wait for any outstanding gate and then make sure we're
 267          * ungated before exiting.
 268          */
 269         if (cancel_delayed_work_sync(&host->clk_gate_work))
 270                 mmc_host_clk_gate_delayed(host);
 271         if (host->clk_gated)
 272                 mmc_host_clk_hold(host);
 273         /* There should be only one user now */
 274         WARN_ON(host->clk_requests > 1);
 275 }
 276
 277 static inline void mmc_host_clk_sysfs_init(struct mmc_host *host)
 278 {
 279         host->clkgate_delay_attr.show = clkgate_delay_show;
 280         host->clkgate_delay_attr.store = clkgate_delay_store;
 281         sysfs_attr_init(&host->clkgate_delay_attr.attr);
 282         host->clkgate_delay_attr.attr.name = "clkgate_delay";
 283         host->clkgate_delay_attr.attr.mode = S_IRUGO | S_IWUSR;
 284         if (device_create_file(&host->class_dev, &host->clkgate_delay_attr))
 285                 pr_err("%s: Failed to create clkgate_delay sysfs entry\n",
 286                                 mmc_hostname(host));
 287 }
 288 #else
 289
 290 static inline void mmc_host_clk_init(struct mmc_host *host)
 291 {
 292 }
 293
 294 static inline void mmc_host_clk_exit(struct mmc_host *host)
 295 {
 296 }
 297
 298 static inline void mmc_host_clk_sysfs_init(struct mmc_host *host)
 299 {
 300 }
 301
 302 #endif
 303
 304 void mmc_retune_enable(struct mmc_host *host)
 305 {
 306         host->can_retune = 1;
 307         if (host->retune_period)
 308                 mod_timer(&host->retune_timer,
 309                           jiffies + host->retune_period * HZ);
 310 }
 311
 312 void mmc_retune_disable(struct mmc_host *host)
 313 {
 314         host->can_retune = 0;
 315         del_timer_sync(&host->retune_timer);
 316         host->retune_now = 0;
 317         host->need_retune = 0;
 318 }
 319
 320 void mmc_retune_timer_stop(struct mmc_host *host)
 321 {
 322         del_timer_sync(&host->retune_timer);
 323 }
 324 EXPORT_SYMBOL(mmc_retune_timer_stop);
 325
 326 void mmc_retune_hold(struct mmc_host *host)
 327 {
 328         if (!host->hold_retune)
 329                 host->retune_now = 1;
 330         host->hold_retune += 1;
 331 }
 332
 333 void mmc_retune_release(struct mmc_host *host)
 334 {
 335         if (host->hold_retune)
 336                 host->hold_retune -= 1;
 337         else
 338                 WARN_ON(1);
 339 }
 340
 341 int mmc_retune(struct mmc_host *host)
 342 {
 343         bool return_to_hs400 = false;
 344         int err;
 345
 346         if (host->retune_now)
 347                 host->retune_now = 0;
 348         else
 349                 return 0;
 350
 351         if (!host->need_retune || host->doing_retune || !host->card)
 352                 return 0;
 353
 354         host->need_retune = 0;
 355
 356         host->doing_retune = 1;
 357
 358         if (host->ios.timing == MMC_TIMING_MMC_HS400) {
 359                 err = mmc_hs400_to_hs200(host->card);
 360                 if (err)
 361                         goto out;
 362
 363                 return_to_hs400 = true;
 364
 365                 if (host->ops->prepare_hs400_tuning)
 366                         host->ops->prepare_hs400_tuning(host, &host->ios);
 367         }
 368
 369         err = mmc_execute_tuning(host->card);
 370         if (err)
 371                 goto out;
 372
 373         if (return_to_hs400)
 374                 err = mmc_hs200_to_hs400(host->card);
 375 out:
 376         host->doing_retune = 0;
 377
 378         return err;
 379 }
 380
 381 static void mmc_retune_timer(unsigned long data)
 382 {
 383         struct mmc_host *host = (struct mmc_host *)data;
 384
 385         mmc_retune_needed(host);
 386 }
 387
 388 /**
 389  *      mmc_of_parse() - parse host's device-tree node
 390  *      @host: host whose node should be parsed.
 391  *
 392  * To keep the rest of the MMC subsystem unaware of whether DT has been
 393  * used to to instantiate and configure this host instance or not, we
 394  * parse the properties and set respective generic mmc-host flags and
 395  * parameters.
 396  */
 397 int mmc_of_parse(struct mmc_host *host)
 398 {
 399         struct device_node *np;
 400         u32 bus_width;
 401         int ret;
 402         bool cd_cap_invert, cd_gpio_invert = false;
 403         bool ro_cap_invert, ro_gpio_invert = false;
 404
 405         if (!host->parent || !host->parent->of_node)
 406                 return 0;
 407
 408         np = host->parent->of_node;
 409
 410         /* "bus-width" is translated to MMC_CAP_*_BIT_DATA flags */
 411         if (of_property_read_u32(np, "bus-width", &bus_width) < 0) {
 412                 dev_dbg(host->parent,
 413                         "\"bus-width\" property is missing, assuming 1 bit.\n");
 414                 bus_width = 1;
 415         }
 416
 417         switch (bus_width) {
 418         case 8:
 419                 host->caps |= MMC_CAP_8_BIT_DATA;
 420                 /* Hosts capable of 8-bit transfers can also do 4 bits */
 421         case 4:
 422                 host->caps |= MMC_CAP_4_BIT_DATA;
 423                 break;
 424         case 1:
 425                 break;
 426         default:
 427                 dev_err(host->parent,
 428                         "Invalid \"bus-width\" value %u!\n", bus_width);
 429                 return -EINVAL;
 430         }
 431
 432         /* f_max is obtained from the optional "max-frequency" property */
 433         of_property_read_u32(np, "max-frequency", &host->f_max);
 434
 435         /*
 436          * Configure CD and WP pins. They are both by default active low to
 437          * match the SDHCI spec. If GPIOs are provided for CD and / or WP, the
 438          * mmc-gpio helpers are used to attach, configure and use them. If
 439          * polarity inversion is specified in DT, one of MMC_CAP2_CD_ACTIVE_HIGH
 440          * and MMC_CAP2_RO_ACTIVE_HIGH capability-2 flags is set. If the
 441          * "broken-cd" property is provided, the MMC_CAP_NEEDS_POLL capability
 442          * is set. If the "non-removable" property is found, the
 443          * MMC_CAP_NONREMOVABLE capability is set and no card-detection
 444          * configuration is performed.
 445          */
 446
 447         /* Parse Card Detection */
 448         if (of_property_read_bool(np, "non-removable")) {
 449                 host->caps |= MMC_CAP_NONREMOVABLE;
 450         } else {
 451                 cd_cap_invert = of_property_read_bool(np, "cd-inverted");
 452
 453                 if (of_property_read_bool(np, "broken-cd"))
 454                         host->caps |= MMC_CAP_NEEDS_POLL;
 455
 456                 ret = mmc_gpiod_request_cd(host, "cd", 0, true,
 457                                            0, &cd_gpio_invert);
 458                 if (!ret)
 459                         dev_info(host->parent, "Got CD GPIO\n");
 460                 else if (ret != -ENOENT && ret != -ENOSYS)
 461                         return ret;
 462
 463                 /*
 464                  * There are two ways to flag that the CD line is inverted:
 465                  * through the cd-inverted flag and by the GPIO line itself
 466                  * being inverted from the GPIO subsystem. This is a leftover
 467                  * from the times when the GPIO subsystem did not make it
 468                  * possible to flag a line as inverted.
 469                  *
 470                  * If the capability on the host AND the GPIO line are
 471                  * both inverted, the end result is that the CD line is
 472                  * not inverted.
 473                  */
 474                 if (cd_cap_invert ^ cd_gpio_invert)
 475                         host->caps2 |= MMC_CAP2_CD_ACTIVE_HIGH;
 476         }
 477
 478         /* Parse Write Protection */
 479         ro_cap_invert = of_property_read_bool(np, "wp-inverted");
 480
 481         ret = mmc_gpiod_request_ro(host, "wp", 0, false, 0, &ro_gpio_invert);
 482         if (!ret)
 483                 dev_info(host->parent, "Got WP GPIO\n");
 484         else if (ret != -ENOENT && ret != -ENOSYS)
 485                 return ret;
 486
 487         if (of_property_read_bool(np, "disable-wp"))
 488                 host->caps2 |= MMC_CAP2_NO_WRITE_PROTECT;
 489
 490         /* See the comment on CD inversion above */
 491         if (ro_cap_invert ^ ro_gpio_invert)
 492                 host->caps2 |= MMC_CAP2_RO_ACTIVE_HIGH;
 493
 494         if (of_property_read_bool(np, "cap-sd-highspeed"))
 495                 host->caps |= MMC_CAP_SD_HIGHSPEED;
 496         if (of_property_read_bool(np, "cap-mmc-highspeed"))
 497                 host->caps |= MMC_CAP_MMC_HIGHSPEED;
 498         if (of_property_read_bool(np, "sd-uhs-sdr12"))
 499                 host->caps |= MMC_CAP_UHS_SDR12;
 500         if (of_property_read_bool(np, "sd-uhs-sdr25"))
 501                 host->caps |= MMC_CAP_UHS_SDR25;
 502         if (of_property_read_bool(np, "sd-uhs-sdr50"))
 503                 host->caps |= MMC_CAP_UHS_SDR50;
 504         if (of_property_read_bool(np, "sd-uhs-sdr104"))
 505                 host->caps |= MMC_CAP_UHS_SDR104;
 506         if (of_property_read_bool(np, "sd-uhs-ddr50"))
 507                 host->caps |= MMC_CAP_UHS_DDR50;
 508         if (of_property_read_bool(np, "cap-power-off-card"))
 509                 host->caps |= MMC_CAP_POWER_OFF_CARD;
 510         if (of_property_read_bool(np, "cap-sdio-irq"))
 511                 host->caps |= MMC_CAP_SDIO_IRQ;
 512         if (of_property_read_bool(np, "full-pwr-cycle"))
 513                 host->caps2 |= MMC_CAP2_FULL_PWR_CYCLE;
 514         if (of_property_read_bool(np, "keep-power-in-suspend"))
 515                 host->pm_caps |= MMC_PM_KEEP_POWER;
 516         if (of_property_read_bool(np, "enable-sdio-wakeup"))
 517                 host->pm_caps |= MMC_PM_WAKE_SDIO_IRQ;
 518         if (of_property_read_bool(np, "mmc-ddr-1_8v"))
 519                 host->caps |= MMC_CAP_1_8V_DDR;
 520         if (of_property_read_bool(np, "mmc-ddr-1_2v"))
 521                 host->caps |= MMC_CAP_1_2V_DDR;
 522         if (of_property_read_bool(np, "mmc-hs200-1_8v"))
 523                 host->caps2 |= MMC_CAP2_HS200_1_8V_SDR;
 524         if (of_property_read_bool(np, "mmc-hs200-1_2v"))
 525                 host->caps2 |= MMC_CAP2_HS200_1_2V_SDR;
 526         if (of_property_read_bool(np, "mmc-hs400-1_8v"))
 527                 host->caps2 |= MMC_CAP2_HS400_1_8V | MMC_CAP2_HS200_1_8V_SDR;
 528         if (of_property_read_bool(np, "mmc-hs400-1_2v"))
 529                 host->caps2 |= MMC_CAP2_HS400_1_2V | MMC_CAP2_HS200_1_2V_SDR;
 530
 531         host->dsr_req = !of_property_read_u32(np, "dsr", &host->dsr);
 532         if (host->dsr_req && (host->dsr & ~0xffff)) {
 533                 dev_err(host->parent,
 534                         "device tree specified broken value for DSR: 0x%x, ignoring\n",
 535                         host->dsr);
 536                 host->dsr_req = 0;
 537         }
 538
 539         return mmc_pwrseq_alloc(host);
 540 }
 541
 542 EXPORT_SYMBOL(mmc_of_parse);
 543
 544 /**
 545  *      mmc_alloc_host - initialise the per-host structure.
 546  *      @extra: sizeof private data structure
 547  *      @dev: pointer to host device model structure
 548  *
 549  *      Initialise the per-host structure.
 550  */
 551 struct mmc_host *mmc_alloc_host(int extra, struct device *dev)
 552 {
 553         int err;
 554         struct mmc_host *host;
 555
 556         host = kzalloc(sizeof(struct mmc_host) + extra, GFP_KERNEL);
 557         if (!host)
 558                 return NULL;
 559
 560         /* scanning will be enabled when we're ready */
 561         host->rescan_disable = 1;
 562         idr_preload(GFP_KERNEL);
 563         spin_lock(&mmc_host_lock);
 564         err = idr_alloc(&mmc_host_idr, host, 0, 0, GFP_NOWAIT);
 565         if (err >= 0)
 566                 host->index = err;
 567         spin_unlock(&mmc_host_lock);
 568         idr_preload_end();
 569         if (err < 0) {
 570                 kfree(host);
 571                 return NULL;
 572         }
 573
 574         dev_set_name(&host->class_dev, "mmc%d", host->index);
 575
 576         host->parent = dev;
 577         host->class_dev.parent = dev;
 578         host->class_dev.class = &mmc_host_class;
 579         device_initialize(&host->class_dev);
 580
 581         if (mmc_gpio_alloc(host)) {
 582                 put_device(&host->class_dev);
 583                 return NULL;
 584         }
 585
 586         mmc_host_clk_init(host);
 587
 588         spin_lock_init(&host->lock);
 589         init_waitqueue_head(&host->wq);
 590         INIT_DELAYED_WORK(&host->detect, mmc_rescan);
 591 #ifdef CONFIG_PM
 592         host->pm_notify.notifier_call = mmc_pm_notify;
 593 #endif
 594         setup_timer(&host->retune_timer, mmc_retune_timer, (unsigned long)host);
 595
 596         /*
 597          * By default, hosts do not support SGIO or large requests.
 598          * They have to set these according to their abilities.
 599          */
 600         host->max_segs = 1;
 601         host->max_seg_size = PAGE_CACHE_SIZE;
 602
 603         host->max_req_size = PAGE_CACHE_SIZE;
 604         host->max_blk_size = 512;
 605         host->max_blk_count = PAGE_CACHE_SIZE / 512;
 606
 607         return host;
 608 }
 609
 610 EXPORT_SYMBOL(mmc_alloc_host);
 611
 612 /**
 613  *      mmc_add_host - initialise host hardware
 614  *      @host: mmc host
 615  *
 616  *      Register the host with the driver model. The host must be
 617  *      prepared to start servicing requests before this function
 618  *      completes.
 619  */
 620 int mmc_add_host(struct mmc_host *host)
 621 {
 622         int err;
 623
 624         WARN_ON((host->caps & MMC_CAP_SDIO_IRQ) &&
 625                 !host->ops->enable_sdio_irq);
 626
 627         err = device_add(&host->class_dev);
 628         if (err)
 629                 return err;
 630
 631         led_trigger_register_simple(dev_name(&host->class_dev), &host->led);
 632
 633 #ifdef CONFIG_DEBUG_FS
 634         mmc_add_host_debugfs(host);
 635 #endif
 636         mmc_host_clk_sysfs_init(host);
 637
 638         mmc_start_host(host);
 639         register_pm_notifier(&host->pm_notify);
 640
 641         return 0;
 642 }
 643
 644 EXPORT_SYMBOL(mmc_add_host);
 645
 646 /**
 647  *      mmc_remove_host - remove host hardware
 648  *      @host: mmc host
 649  *
 650  *      Unregister and remove all cards associated with this host,
 651  *      and power down the MMC bus. No new requests will be issued
 652  *      after this function has returned.
 653  */
 654 void mmc_remove_host(struct mmc_host *host)
 655 {
 656         unregister_pm_notifier(&host->pm_notify);
 657         mmc_stop_host(host);
 658
 659 #ifdef CONFIG_DEBUG_FS
 660         mmc_remove_host_debugfs(host);
 661 #endif
 662
 663         device_del(&host->class_dev);
 664
 665         led_trigger_unregister_simple(host->led);
 666
 667         mmc_host_clk_exit(host);
 668 }
 669
 670 EXPORT_SYMBOL(mmc_remove_host);
 671
 672 /**
 673  *      mmc_free_host - free the host structure
 674  *      @host: mmc host
 675  *
 676  *      Free the host once all references to it have been dropped.
 677  */
 678 void mmc_free_host(struct mmc_host *host)
 679 {
 680         mmc_pwrseq_free(host);
 681         put_device(&host->class_dev);
 682 }
 683
 684 EXPORT_SYMBOL(mmc_free_host);