block/blk-pm.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include <linux/blk-mq.h>
   4 #include <linux/blk-pm.h>
   5 #include <linux/blkdev.h>
   6 #include <linux/pm_runtime.h>
   7 #include "blk-mq.h"
   8 #include "blk-mq-tag.h"
   9
  10 /**
  11  * blk_pm_runtime_init - Block layer runtime PM initialization routine
  12  * @q: the queue of the device
  13  * @dev: the device the queue belongs to
  14  *
  15  * Description:
  16  *    Initialize runtime-PM-related fields for @q and start auto suspend for
  17  *    @dev. Drivers that want to take advantage of request-based runtime PM
  18  *    should call this function after @dev has been initialized, and its
  19  *    request queue @q has been allocated, and runtime PM for it can not happen
  20  *    yet(either due to disabled/forbidden or its usage_count > 0). In most
  21  *    cases, driver should call this function before any I/O has taken place.
  22  *
  23  *    This function takes care of setting up using auto suspend for the device,
  24  *    the autosuspend delay is set to -1 to make runtime suspend impossible
  25  *    until an updated value is either set by user or by driver. Drivers do
  26  *    not need to touch other autosuspend settings.
  27  *
  28  *    The block layer runtime PM is request based, so only works for drivers
  29  *    that use request as their IO unit instead of those directly use bio's.
  30  */
  31 void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
  32 {
  33         q->dev = dev;
  34         q->rpm_status = RPM_ACTIVE;
  35         pm_runtime_set_autosuspend_delay(q->dev, -1);
  36         pm_runtime_use_autosuspend(q->dev);
  37 }
  38 EXPORT_SYMBOL(blk_pm_runtime_init);
  39
  40 /**
  41  * blk_pre_runtime_suspend - Pre runtime suspend check
  42  * @q: the queue of the device
  43  *
  44  * Description:
  45  *    This function will check if runtime suspend is allowed for the device
  46  *    by examining if there are any requests pending in the queue. If there
  47  *    are requests pending, the device can not be runtime suspended; otherwise,
  48  *    the queue's status will be updated to SUSPENDING and the driver can
  49  *    proceed to suspend the device.
  50  *
  51  *    For the not allowed case, we mark last busy for the device so that
  52  *    runtime PM core will try to autosuspend it some time later.
  53  *
  54  *    This function should be called near the start of the device's
  55  *    runtime_suspend callback.
  56  *
  57  * Return:
  58  *    0         - OK to runtime suspend the device
  59  *    -EBUSY    - Device should not be runtime suspended
  60  */
  61 int blk_pre_runtime_suspend(struct request_queue *q)
  62 {
  63         int ret = 0;
  64
  65         if (!q->dev)
  66                 return ret;
  67
  68         WARN_ON_ONCE(q->rpm_status != RPM_ACTIVE);
  69
  70         /*
  71          * Increase the pm_only counter before checking whether any
  72          * non-PM blk_queue_enter() calls are in progress to avoid that any
  73          * new non-PM blk_queue_enter() calls succeed before the pm_only
  74          * counter is decreased again.
  75          */
  76         blk_set_pm_only(q);
  77         ret = -EBUSY;
  78         /* Switch q_usage_counter from per-cpu to atomic mode. */
  79         blk_freeze_queue_start(q);
  80         /*
  81          * Wait until atomic mode has been reached. Since that
  82          * involves calling call_rcu(), it is guaranteed that later
  83          * blk_queue_enter() calls see the pm-only state. See also
  84          * http://lwn.net/Articles/573497/.
  85          */
  86         percpu_ref_switch_to_atomic_sync(&q->q_usage_counter);
  87         if (percpu_ref_is_zero(&q->q_usage_counter))
  88                 ret = 0;
  89         /* Switch q_usage_counter back to per-cpu mode. */
  90         blk_mq_unfreeze_queue(q);
  91
  92         spin_lock_irq(&q->queue_lock);
  93         if (ret < 0)
  94                 pm_runtime_mark_last_busy(q->dev);
  95         else
  96                 q->rpm_status = RPM_SUSPENDING;
  97         spin_unlock_irq(&q->queue_lock);
  98
  99         if (ret)
 100                 blk_clear_pm_only(q);
 101
 102         return ret;
 103 }
 104 EXPORT_SYMBOL(blk_pre_runtime_suspend);
 105
 106 /**
 107  * blk_post_runtime_suspend - Post runtime suspend processing
 108  * @q: the queue of the device
 109  * @err: return value of the device's runtime_suspend function
 110  *
 111  * Description:
 112  *    Update the queue's runtime status according to the return value of the
 113  *    device's runtime suspend function and mark last busy for the device so
 114  *    that PM core will try to auto suspend the device at a later time.
 115  *
 116  *    This function should be called near the end of the device's
 117  *    runtime_suspend callback.
 118  */
 119 void blk_post_runtime_suspend(struct request_queue *q, int err)
 120 {
 121         if (!q->dev)
 122                 return;
 123
 124         spin_lock_irq(&q->queue_lock);
 125         if (!err) {
 126                 q->rpm_status = RPM_SUSPENDED;
 127         } else {
 128                 q->rpm_status = RPM_ACTIVE;
 129                 pm_runtime_mark_last_busy(q->dev);
 130         }
 131         spin_unlock_irq(&q->queue_lock);
 132
 133         if (err)
 134                 blk_clear_pm_only(q);
 135 }
 136 EXPORT_SYMBOL(blk_post_runtime_suspend);
 137
 138 /**
 139  * blk_pre_runtime_resume - Pre runtime resume processing
 140  * @q: the queue of the device
 141  *
 142  * Description:
 143  *    Update the queue's runtime status to RESUMING in preparation for the
 144  *    runtime resume of the device.
 145  *
 146  *    This function should be called near the start of the device's
 147  *    runtime_resume callback.
 148  */
 149 void blk_pre_runtime_resume(struct request_queue *q)
 150 {
 151         if (!q->dev)
 152                 return;
 153
 154         spin_lock_irq(&q->queue_lock);
 155         q->rpm_status = RPM_RESUMING;
 156         spin_unlock_irq(&q->queue_lock);
 157 }
 158 EXPORT_SYMBOL(blk_pre_runtime_resume);
 159
 160 /**
 161  * blk_post_runtime_resume - Post runtime resume processing
 162  * @q: the queue of the device
 163  * @err: return value of the device's runtime_resume function
 164  *
 165  * Description:
 166  *    Update the queue's runtime status according to the return value of the
 167  *    device's runtime_resume function. If the resume was successful, call
 168  *    blk_set_runtime_active() to do the real work of restarting the queue.
 169  *
 170  *    This function should be called near the end of the device's
 171  *    runtime_resume callback.
 172  */
 173 void blk_post_runtime_resume(struct request_queue *q, int err)
 174 {
 175         if (!q->dev)
 176                 return;
 177         if (!err) {
 178                 blk_set_runtime_active(q);
 179         } else {
 180                 spin_lock_irq(&q->queue_lock);
 181                 q->rpm_status = RPM_SUSPENDED;
 182                 spin_unlock_irq(&q->queue_lock);
 183         }
 184 }
 185 EXPORT_SYMBOL(blk_post_runtime_resume);
 186
 187 /**
 188  * blk_set_runtime_active - Force runtime status of the queue to be active
 189  * @q: the queue of the device
 190  *
 191  * If the device is left runtime suspended during system suspend the resume
 192  * hook typically resumes the device and corrects runtime status
 193  * accordingly. However, that does not affect the queue runtime PM status
 194  * which is still "suspended". This prevents processing requests from the
 195  * queue.
 196  *
 197  * This function can be used in driver's resume hook to correct queue
 198  * runtime PM status and re-enable peeking requests from the queue. It
 199  * should be called before first request is added to the queue.
 200  *
 201  * This function is also called by blk_post_runtime_resume() for successful
 202  * runtime resumes.  It does everything necessary to restart the queue.
 203  */
 204 void blk_set_runtime_active(struct request_queue *q)
 205 {
 206         int old_status;
 207
 208         if (!q->dev)
 209                 return;
 210
 211         spin_lock_irq(&q->queue_lock);
 212         old_status = q->rpm_status;
 213         q->rpm_status = RPM_ACTIVE;
 214         pm_runtime_mark_last_busy(q->dev);
 215         pm_request_autosuspend(q->dev);
 216         spin_unlock_irq(&q->queue_lock);
 217
 218         if (old_status != RPM_ACTIVE)
 219                 blk_clear_pm_only(q);
 220 }
 221 EXPORT_SYMBOL(blk_set_runtime_active);