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/pagemap.h>
  19 #include <linux/export.h>
  20 #include <linux/leds.h>
  21 #include <linux/slab.h>
  22 #include <linux/suspend.h>
  23
  24 #include <linux/mmc/host.h>
  25 #include <linux/mmc/card.h>
  26
  27 #include "core.h"
  28 #include "host.h"
  29
  30 #define cls_dev_to_mmc_host(d)  container_of(d, struct mmc_host, class_dev)
  31
  32 static void mmc_host_classdev_release(struct device *dev)
  33 {
  34         struct mmc_host *host = cls_dev_to_mmc_host(dev);
  35         kfree(host);
  36 }
  37
  38 static struct class mmc_host_class = {
  39         .name           = "mmc_host",
  40         .dev_release    = mmc_host_classdev_release,
  41 };
  42
  43 int mmc_register_host_class(void)
  44 {
  45         return class_register(&mmc_host_class);
  46 }
  47
  48 void mmc_unregister_host_class(void)
  49 {
  50         class_unregister(&mmc_host_class);
  51 }
  52
  53 static DEFINE_IDR(mmc_host_idr);
  54 static DEFINE_SPINLOCK(mmc_host_lock);
  55
  56 #ifdef CONFIG_MMC_CLKGATE
  57 static ssize_t clkgate_delay_show(struct device *dev,
  58                 struct device_attribute *attr, char *buf)
  59 {
  60         struct mmc_host *host = cls_dev_to_mmc_host(dev);
  61         return snprintf(buf, PAGE_SIZE, "%lu\n", host->clkgate_delay);
  62 }
  63
  64 static ssize_t clkgate_delay_store(struct device *dev,
  65                 struct device_attribute *attr, const char *buf, size_t count)
  66 {
  67         struct mmc_host *host = cls_dev_to_mmc_host(dev);
  68         unsigned long flags, value;
  69
  70         if (kstrtoul(buf, 0, &value))
  71                 return -EINVAL;
  72
  73         spin_lock_irqsave(&host->clk_lock, flags);
  74         host->clkgate_delay = value;
  75         spin_unlock_irqrestore(&host->clk_lock, flags);
  76         return count;
  77 }
  78
  79 /*
  80  * Enabling clock gating will make the core call out to the host
  81  * once up and once down when it performs a request or card operation
  82  * intermingled in any fashion. The driver will see this through
  83  * set_ios() operations with ios.clock field set to 0 to gate (disable)
  84  * the block clock, and to the old frequency to enable it again.
  85  */
  86 static void mmc_host_clk_gate_delayed(struct mmc_host *host)
  87 {
  88         unsigned long tick_ns;
  89         unsigned long freq = host->ios.clock;
  90         unsigned long flags;
  91
  92         if (!freq) {
  93                 pr_debug("%s: frequency set to 0 in disable function, "
  94                          "this means the clock is already disabled.\n",
  95                          mmc_hostname(host));
  96                 return;
  97         }
  98         /*
  99          * New requests may have appeared while we were scheduling,
 100          * then there is no reason to delay the check before
 101          * clk_disable().
 102          */
 103         spin_lock_irqsave(&host->clk_lock, flags);
 104
 105         /*
 106          * Delay n bus cycles (at least 8 from MMC spec) before attempting
 107          * to disable the MCI block clock. The reference count may have
 108          * gone up again after this delay due to rescheduling!
 109          */
 110         if (!host->clk_requests) {
 111                 spin_unlock_irqrestore(&host->clk_lock, flags);
 112                 tick_ns = DIV_ROUND_UP(1000000000, freq);
 113                 ndelay(host->clk_delay * tick_ns);
 114         } else {
 115                 /* New users appeared while waiting for this work */
 116                 spin_unlock_irqrestore(&host->clk_lock, flags);
 117                 return;
 118         }
 119         mutex_lock(&host->clk_gate_mutex);
 120         spin_lock_irqsave(&host->clk_lock, flags);
 121         if (!host->clk_requests) {
 122                 spin_unlock_irqrestore(&host->clk_lock, flags);
 123                 /* This will set host->ios.clock to 0 */
 124                 mmc_gate_clock(host);
 125                 spin_lock_irqsave(&host->clk_lock, flags);
 126                 pr_debug("%s: gated MCI clock\n", mmc_hostname(host));
 127         }
 128         spin_unlock_irqrestore(&host->clk_lock, flags);
 129         mutex_unlock(&host->clk_gate_mutex);
 130 }
 131
 132 /*
 133  * Internal work. Work to disable the clock at some later point.
 134  */
 135 static void mmc_host_clk_gate_work(struct work_struct *work)
 136 {
 137         struct mmc_host *host = container_of(work, struct mmc_host,
 138                                               clk_gate_work.work);
 139
 140         mmc_host_clk_gate_delayed(host);
 141 }
 142
 143 /**
 144  *      mmc_host_clk_hold - ungate hardware MCI clocks
 145  *      @host: host to ungate.
 146  *
 147  *      Makes sure the host ios.clock is restored to a non-zero value
 148  *      past this call. Increase clock reference count and ungate clock
 149  *      if we're the first user.
 150  */
 151 void mmc_host_clk_hold(struct mmc_host *host)
 152 {
 153         unsigned long flags;
 154
 155         /* cancel any clock gating work scheduled by mmc_host_clk_release() */
 156         cancel_delayed_work_sync(&host->clk_gate_work);
 157         mutex_lock(&host->clk_gate_mutex);
 158         spin_lock_irqsave(&host->clk_lock, flags);
 159         if (host->clk_gated) {
 160                 spin_unlock_irqrestore(&host->clk_lock, flags);
 161                 mmc_ungate_clock(host);
 162                 spin_lock_irqsave(&host->clk_lock, flags);
 163                 pr_debug("%s: ungated MCI clock\n", mmc_hostname(host));
 164         }
 165         host->clk_requests++;
 166         spin_unlock_irqrestore(&host->clk_lock, flags);
 167         mutex_unlock(&host->clk_gate_mutex);
 168 }
 169
 170 /**
 171  *      mmc_host_may_gate_card - check if this card may be gated
 172  *      @card: card to check.
 173  */
 174 static bool mmc_host_may_gate_card(struct mmc_card *card)
 175 {
 176         /* If there is no card we may gate it */
 177         if (!card)
 178                 return true;
 179         /*
 180          * Don't gate SDIO cards! These need to be clocked at all times
 181          * since they may be independent systems generating interrupts
 182          * and other events. The clock requests counter from the core will
 183          * go down to zero since the core does not need it, but we will not
 184          * gate the clock, because there is somebody out there that may still
 185          * be using it.
 186          */
 187         return !(card->quirks & MMC_QUIRK_BROKEN_CLK_GATING);
 188 }
 189
 190 /**
 191  *      mmc_host_clk_release - gate off hardware MCI clocks
 192  *      @host: host to gate.
 193  *
 194  *      Calls the host driver with ios.clock set to zero as often as possible
 195  *      in order to gate off hardware MCI clocks. Decrease clock reference
 196  *      count and schedule disabling of clock.
 197  */
 198 void mmc_host_clk_release(struct mmc_host *host)
 199 {
 200         unsigned long flags;
 201
 202         spin_lock_irqsave(&host->clk_lock, flags);
 203         host->clk_requests--;
 204         if (mmc_host_may_gate_card(host->card) &&
 205             !host->clk_requests)
 206                 queue_delayed_work(system_nrt_wq, &host->clk_gate_work,
 207                                 msecs_to_jiffies(host->clkgate_delay));
 208         spin_unlock_irqrestore(&host->clk_lock, flags);
 209 }
 210
 211 /**
 212  *      mmc_host_clk_rate - get current clock frequency setting
 213  *      @host: host to get the clock frequency for.
 214  *
 215  *      Returns current clock frequency regardless of gating.
 216  */
 217 unsigned int mmc_host_clk_rate(struct mmc_host *host)
 218 {
 219         unsigned long freq;
 220         unsigned long flags;
 221
 222         spin_lock_irqsave(&host->clk_lock, flags);
 223         if (host->clk_gated)
 224                 freq = host->clk_old;
 225         else
 226                 freq = host->ios.clock;
 227         spin_unlock_irqrestore(&host->clk_lock, flags);
 228         return freq;
 229 }
 230
 231 /**
 232  *      mmc_host_clk_init - set up clock gating code
 233  *      @host: host with potential clock to control
 234  */
 235 static inline void mmc_host_clk_init(struct mmc_host *host)
 236 {
 237         host->clk_requests = 0;
 238         /* Hold MCI clock for 8 cycles by default */
 239         host->clk_delay = 8;
 240         /*
 241          * Default clock gating delay is 0ms to avoid wasting power.
 242          * This value can be tuned by writing into sysfs entry.
 243          */
 244         host->clkgate_delay = 0;
 245         host->clk_gated = false;
 246         INIT_DELAYED_WORK(&host->clk_gate_work, mmc_host_clk_gate_work);
 247         spin_lock_init(&host->clk_lock);
 248         mutex_init(&host->clk_gate_mutex);
 249 }
 250
 251 /**
 252  *      mmc_host_clk_exit - shut down clock gating code
 253  *      @host: host with potential clock to control
 254  */
 255 static inline void mmc_host_clk_exit(struct mmc_host *host)
 256 {
 257         /*
 258          * Wait for any outstanding gate and then make sure we're
 259          * ungated before exiting.
 260          */
 261         if (cancel_delayed_work_sync(&host->clk_gate_work))
 262                 mmc_host_clk_gate_delayed(host);
 263         if (host->clk_gated)
 264                 mmc_host_clk_hold(host);
 265         /* There should be only one user now */
 266         WARN_ON(host->clk_requests > 1);
 267 }
 268
 269 static inline void mmc_host_clk_sysfs_init(struct mmc_host *host)
 270 {
 271         host->clkgate_delay_attr.show = clkgate_delay_show;
 272         host->clkgate_delay_attr.store = clkgate_delay_store;
 273         sysfs_attr_init(&host->clkgate_delay_attr.attr);
 274         host->clkgate_delay_attr.attr.name = "clkgate_delay";
 275         host->clkgate_delay_attr.attr.mode = S_IRUGO | S_IWUSR;
 276         if (device_create_file(&host->class_dev, &host->clkgate_delay_attr))
 277                 pr_err("%s: Failed to create clkgate_delay sysfs entry\n",
 278                                 mmc_hostname(host));
 279 }
 280 #else
 281
 282 static inline void mmc_host_clk_init(struct mmc_host *host)
 283 {
 284 }
 285
 286 static inline void mmc_host_clk_exit(struct mmc_host *host)
 287 {
 288 }
 289
 290 static inline void mmc_host_clk_sysfs_init(struct mmc_host *host)
 291 {
 292 }
 293
 294 #endif
 295
 296 /**
 297  *      mmc_alloc_host - initialise the per-host structure.
 298  *      @extra: sizeof private data structure
 299  *      @dev: pointer to host device model structure
 300  *
 301  *      Initialise the per-host structure.
 302  */
 303 struct mmc_host *mmc_alloc_host(int extra, struct device *dev)
 304 {
 305         int err;
 306         struct mmc_host *host;
 307
 308         if (!idr_pre_get(&mmc_host_idr, GFP_KERNEL))
 309                 return NULL;
 310
 311         host = kzalloc(sizeof(struct mmc_host) + extra, GFP_KERNEL);
 312         if (!host)
 313                 return NULL;
 314
 315         spin_lock(&mmc_host_lock);
 316         err = idr_get_new(&mmc_host_idr, host, &host->index);
 317         spin_unlock(&mmc_host_lock);
 318         if (err)
 319                 goto free;
 320
 321         dev_set_name(&host->class_dev, "mmc%d", host->index);
 322
 323         host->parent = dev;
 324         host->class_dev.parent = dev;
 325         host->class_dev.class = &mmc_host_class;
 326         device_initialize(&host->class_dev);
 327
 328         mmc_host_clk_init(host);
 329
 330         spin_lock_init(&host->lock);
 331         init_waitqueue_head(&host->wq);
 332         INIT_DELAYED_WORK(&host->detect, mmc_rescan);
 333 #ifdef CONFIG_PM
 334         host->pm_notify.notifier_call = mmc_pm_notify;
 335 #endif
 336
 337         /*
 338          * By default, hosts do not support SGIO or large requests.
 339          * They have to set these according to their abilities.
 340          */
 341         host->max_segs = 1;
 342         host->max_seg_size = PAGE_CACHE_SIZE;
 343
 344         host->max_req_size = PAGE_CACHE_SIZE;
 345         host->max_blk_size = 512;
 346         host->max_blk_count = PAGE_CACHE_SIZE / 512;
 347
 348         return host;
 349
 350 free:
 351         kfree(host);
 352         return NULL;
 353 }
 354
 355 EXPORT_SYMBOL(mmc_alloc_host);
 356
 357 /**
 358  *      mmc_add_host - initialise host hardware
 359  *      @host: mmc host
 360  *
 361  *      Register the host with the driver model. The host must be
 362  *      prepared to start servicing requests before this function
 363  *      completes.
 364  */
 365 int mmc_add_host(struct mmc_host *host)
 366 {
 367         int err;
 368
 369         WARN_ON((host->caps & MMC_CAP_SDIO_IRQ) &&
 370                 !host->ops->enable_sdio_irq);
 371
 372         err = device_add(&host->class_dev);
 373         if (err)
 374                 return err;
 375
 376         led_trigger_register_simple(dev_name(&host->class_dev), &host->led);
 377
 378 #ifdef CONFIG_DEBUG_FS
 379         mmc_add_host_debugfs(host);
 380 #endif
 381         mmc_host_clk_sysfs_init(host);
 382
 383         mmc_start_host(host);
 384         register_pm_notifier(&host->pm_notify);
 385
 386         return 0;
 387 }
 388
 389 EXPORT_SYMBOL(mmc_add_host);
 390
 391 /**
 392  *      mmc_remove_host - remove host hardware
 393  *      @host: mmc host
 394  *
 395  *      Unregister and remove all cards associated with this host,
 396  *      and power down the MMC bus. No new requests will be issued
 397  *      after this function has returned.
 398  */
 399 void mmc_remove_host(struct mmc_host *host)
 400 {
 401         unregister_pm_notifier(&host->pm_notify);
 402         mmc_stop_host(host);
 403
 404 #ifdef CONFIG_DEBUG_FS
 405         mmc_remove_host_debugfs(host);
 406 #endif
 407
 408         device_del(&host->class_dev);
 409
 410         led_trigger_unregister_simple(host->led);
 411
 412         mmc_host_clk_exit(host);
 413 }
 414
 415 EXPORT_SYMBOL(mmc_remove_host);
 416
 417 /**
 418  *      mmc_free_host - free the host structure
 419  *      @host: mmc host
 420  *
 421  *      Free the host once all references to it have been dropped.
 422  */
 423 void mmc_free_host(struct mmc_host *host)
 424 {
 425         spin_lock(&mmc_host_lock);
 426         idr_remove(&mmc_host_idr, host->index);
 427         spin_unlock(&mmc_host_lock);
 428
 429         put_device(&host->class_dev);
 430 }
 431
 432 EXPORT_SYMBOL(mmc_free_host);