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 spin_lock_irq(&q->queue_lock); 71 q->rpm_status = RPM_SUSPENDING; 72 spin_unlock_irq(&q->queue_lock); 73 74 /* 75 * Increase the pm_only counter before checking whether any 76 * non-PM blk_queue_enter() calls are in progress to avoid that any 77 * new non-PM blk_queue_enter() calls succeed before the pm_only 78 * counter is decreased again. 79 */ 80 blk_set_pm_only(q); 81 ret = -EBUSY; 82 /* Switch q_usage_counter from per-cpu to atomic mode. */ 83 blk_freeze_queue_start(q); 84 /* 85 * Wait until atomic mode has been reached. Since that 86 * involves calling call_rcu(), it is guaranteed that later 87 * blk_queue_enter() calls see the pm-only state. See also 88 * http://lwn.net/Articles/573497/. 89 */ 90 percpu_ref_switch_to_atomic_sync(&q->q_usage_counter); 91 if (percpu_ref_is_zero(&q->q_usage_counter)) 92 ret = 0; 93 /* Switch q_usage_counter back to per-cpu mode. */ 94 blk_mq_unfreeze_queue(q); 95 96 if (ret < 0) { 97 spin_lock_irq(&q->queue_lock); 98 q->rpm_status = RPM_ACTIVE; 99 pm_runtime_mark_last_busy(q->dev); 100 spin_unlock_irq(&q->queue_lock); 101 102 blk_clear_pm_only(q); 103 } 104 105 return ret; 106 } 107 EXPORT_SYMBOL(blk_pre_runtime_suspend); 108 109 /** 110 * blk_post_runtime_suspend - Post runtime suspend processing 111 * @q: the queue of the device 112 * @err: return value of the device's runtime_suspend function 113 * 114 * Description: 115 * Update the queue's runtime status according to the return value of the 116 * device's runtime suspend function and mark last busy for the device so 117 * that PM core will try to auto suspend the device at a later time. 118 * 119 * This function should be called near the end of the device's 120 * runtime_suspend callback. 121 */ 122 void blk_post_runtime_suspend(struct request_queue *q, int err) 123 { 124 if (!q->dev) 125 return; 126 127 spin_lock_irq(&q->queue_lock); 128 if (!err) { 129 q->rpm_status = RPM_SUSPENDED; 130 } else { 131 q->rpm_status = RPM_ACTIVE; 132 pm_runtime_mark_last_busy(q->dev); 133 } 134 spin_unlock_irq(&q->queue_lock); 135 136 if (err) 137 blk_clear_pm_only(q); 138 } 139 EXPORT_SYMBOL(blk_post_runtime_suspend); 140 141 /** 142 * blk_pre_runtime_resume - Pre runtime resume processing 143 * @q: the queue of the device 144 * 145 * Description: 146 * Update the queue's runtime status to RESUMING in preparation for the 147 * runtime resume of the device. 148 * 149 * This function should be called near the start of the device's 150 * runtime_resume callback. 151 */ 152 void blk_pre_runtime_resume(struct request_queue *q) 153 { 154 if (!q->dev) 155 return; 156 157 spin_lock_irq(&q->queue_lock); 158 q->rpm_status = RPM_RESUMING; 159 spin_unlock_irq(&q->queue_lock); 160 } 161 EXPORT_SYMBOL(blk_pre_runtime_resume); 162 163 /** 164 * blk_post_runtime_resume - Post runtime resume processing 165 * @q: the queue of the device 166 * 167 * Description: 168 * For historical reasons, this routine merely calls blk_set_runtime_active() 169 * to do the real work of restarting the queue. It does this regardless of 170 * whether the device's runtime-resume succeeded; even if it failed the 171 * driver or error handler will need to communicate with the device. 172 * 173 * This function should be called near the end of the device's 174 * runtime_resume callback. 175 */ 176 void blk_post_runtime_resume(struct request_queue *q) 177 { 178 blk_set_runtime_active(q); 179 } 180 EXPORT_SYMBOL(blk_post_runtime_resume); 181 182 /** 183 * blk_set_runtime_active - Force runtime status of the queue to be active 184 * @q: the queue of the device 185 * 186 * If the device is left runtime suspended during system suspend the resume 187 * hook typically resumes the device and corrects runtime status 188 * accordingly. However, that does not affect the queue runtime PM status 189 * which is still "suspended". This prevents processing requests from the 190 * queue. 191 * 192 * This function can be used in driver's resume hook to correct queue 193 * runtime PM status and re-enable peeking requests from the queue. It 194 * should be called before first request is added to the queue. 195 * 196 * This function is also called by blk_post_runtime_resume() for 197 * runtime resumes. It does everything necessary to restart the queue. 198 */ 199 void blk_set_runtime_active(struct request_queue *q) 200 { 201 int old_status; 202 203 if (!q->dev) 204 return; 205 206 spin_lock_irq(&q->queue_lock); 207 old_status = q->rpm_status; 208 q->rpm_status = RPM_ACTIVE; 209 pm_runtime_mark_last_busy(q->dev); 210 pm_request_autosuspend(q->dev); 211 spin_unlock_irq(&q->queue_lock); 212 213 if (old_status != RPM_ACTIVE) 214 blk_clear_pm_only(q); 215 } 216 EXPORT_SYMBOL(blk_set_runtime_active); 217