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 */
blk_pm_runtime_init(struct request_queue * q,struct device * dev)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 */
blk_pre_runtime_suspend(struct request_queue * q)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 */
blk_post_runtime_suspend(struct request_queue * q,int err)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 */
blk_pre_runtime_resume(struct request_queue * q)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 * @err: return value of the device's runtime_resume function
167 *
168 * Description:
169 * Update the queue's runtime status according to the return value of the
170 * device's runtime_resume function. If the resume was successful, call
171 * blk_set_runtime_active() to do the real work of restarting the queue.
172 *
173 * This function should be called near the end of the device's
174 * runtime_resume callback.
175 */
blk_post_runtime_resume(struct request_queue * q,int err)176 void blk_post_runtime_resume(struct request_queue *q, int err)
177 {
178 if (!q->dev)
179 return;
180 if (!err) {
181 blk_set_runtime_active(q);
182 } else {
183 spin_lock_irq(&q->queue_lock);
184 q->rpm_status = RPM_SUSPENDED;
185 spin_unlock_irq(&q->queue_lock);
186 }
187 }
188 EXPORT_SYMBOL(blk_post_runtime_resume);
189
190 /**
191 * blk_set_runtime_active - Force runtime status of the queue to be active
192 * @q: the queue of the device
193 *
194 * If the device is left runtime suspended during system suspend the resume
195 * hook typically resumes the device and corrects runtime status
196 * accordingly. However, that does not affect the queue runtime PM status
197 * which is still "suspended". This prevents processing requests from the
198 * queue.
199 *
200 * This function can be used in driver's resume hook to correct queue
201 * runtime PM status and re-enable peeking requests from the queue. It
202 * should be called before first request is added to the queue.
203 *
204 * This function is also called by blk_post_runtime_resume() for successful
205 * runtime resumes. It does everything necessary to restart the queue.
206 */
blk_set_runtime_active(struct request_queue * q)207 void blk_set_runtime_active(struct request_queue *q)
208 {
209 int old_status;
210
211 if (!q->dev)
212 return;
213
214 spin_lock_irq(&q->queue_lock);
215 old_status = q->rpm_status;
216 q->rpm_status = RPM_ACTIVE;
217 pm_runtime_mark_last_busy(q->dev);
218 pm_request_autosuspend(q->dev);
219 spin_unlock_irq(&q->queue_lock);
220
221 if (old_status != RPM_ACTIVE)
222 blk_clear_pm_only(q);
223 }
224 EXPORT_SYMBOL(blk_set_runtime_active);
225
