[PATCH v6 2/4] block: add runtime pm helpers

[Aaron Lu <aaron.lu@xxxxxxxxx>]

From: Lin Ming <ming.m.lin@xxxxxxxxx>

Add runtime pm helper functions:

void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
  - Initialization function for drivers to call.

int blk_pre_runtime_suspend(struct request_queue *q)
  - If any requests are in the queue, return -EBUSY.
    Otherwise set q->rpm_status to RPM_SUSPENDING and return 0.

void blk_post_runtime_suspend(struct request_queue *q, int err)
  - If the suspend succeeded then set q->rpm_status to RPM_SUSPENDED.
    Otherwise set it to RPM_ACTIVE.

void blk_pre_runtime_resume(struct request_queue *q)
  - Set q->rpm_status to RPM_RESUMING.

void blk_post_runtime_resume(struct request_queue *q, int err)
  - If the resume succeeded then set q->rpm_status to RPM_ACTIVE
    and call __blk_run_queue.
    Otherwise set q->rpm_status to RPM_SUSPENDED.

[aaron.lu@xxxxxxxxx: do not touch last busy in these helper functions]
Signed-off-by: Lin Ming <ming.m.lin@xxxxxxxxx>
Signed-off-by: Aaron Lu <aaron.lu@xxxxxxxxx>
---
 block/blk-core.c       | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/blkdev.h | 28 +++++++++++++++++++++++++
 2 files changed, 83 insertions(+)

diff --git a/block/blk-core.c b/block/blk-core.c
index c973249..6fc24bb 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -3055,6 +3055,61 @@ void blk_finish_plug(struct blk_plug *plug)
 }
 EXPORT_SYMBOL(blk_finish_plug);
 
+#ifdef CONFIG_PM_RUNTIME
+void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
+{
+	q->dev = dev;
+	q->rpm_status = RPM_ACTIVE;
+	pm_runtime_use_autosuspend(q->dev);
+}
+EXPORT_SYMBOL(blk_pm_runtime_init);
+
+int blk_pre_runtime_suspend(struct request_queue *q)
+{
+	int ret = 0;
+
+	spin_lock_irq(q->queue_lock);
+	if (q->nr_pending)
+		ret = -EBUSY;
+	else
+		q->rpm_status = RPM_SUSPENDING;
+	spin_unlock_irq(q->queue_lock);
+	return ret;
+}
+EXPORT_SYMBOL(blk_pre_runtime_suspend);
+
+void blk_post_runtime_suspend(struct request_queue *q, int err)
+{
+	spin_lock_irq(q->queue_lock);
+	if (!err)
+		q->rpm_status = RPM_SUSPENDED;
+	else
+		q->rpm_status = RPM_ACTIVE;
+	spin_unlock_irq(q->queue_lock);
+}
+EXPORT_SYMBOL(blk_post_runtime_suspend);
+
+void blk_pre_runtime_resume(struct request_queue *q)
+{
+	spin_lock_irq(q->queue_lock);
+	q->rpm_status = RPM_RESUMING;
+	spin_unlock_irq(q->queue_lock);
+}
+EXPORT_SYMBOL(blk_pre_runtime_resume);
+
+void blk_post_runtime_resume(struct request_queue *q, int err)
+{
+	spin_lock_irq(q->queue_lock);
+	if (!err) {
+		q->rpm_status = RPM_ACTIVE;
+		__blk_run_queue(q);
+	} else
+		q->rpm_status = RPM_SUSPENDED;
+	spin_unlock_irq(q->queue_lock);
+}
+EXPORT_SYMBOL(blk_post_runtime_resume);
+#endif
+
 int __init blk_dev_init(void)
 {
 	BUILD_BUG_ON(__REQ_NR_BITS > 8 *
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index f94bc83..a96e144 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -19,6 +19,7 @@
 #include <linux/gfp.h>
 #include <linux/bsg.h>
 #include <linux/smp.h>
+#include <linux/pm_runtime.h>
 
 #include <asm/scatterlist.h>
 
@@ -360,6 +361,12 @@ struct request_queue {
 	 */
 	struct kobject kobj;
 
+#ifdef CONFIG_PM_RUNTIME
+	struct device		*dev;
+	int			rpm_status;
+	unsigned int		nr_pending;
+#endif
+
 	/*
 	 * queue settings
 	 */
@@ -959,6 +966,27 @@ struct request_queue *blk_alloc_queue_node(gfp_t, int);
 extern void blk_put_queue(struct request_queue *);
 
 /*
+ * block layer runtime pm functions
+ */
+#ifdef CONFIG_PM_RUNTIME
+extern void blk_pm_runtime_init(struct request_queue *q, struct device *dev);
+extern int blk_pre_runtime_suspend(struct request_queue *q);
+extern void blk_post_runtime_suspend(struct request_queue *q, int err);
+extern void blk_pre_runtime_resume(struct request_queue *q);
+extern void blk_post_runtime_resume(struct request_queue *q, int err);
+#else
+static inline void blk_pm_runtime_init(struct request_queue *q,
+	struct device *dev) {}
+static inline int blk_pre_runtime_suspend(struct request_queue *q)
+{
+	return -ENOSYS;
+}
+static inline void blk_post_runtime_suspend(struct request_queue *q, int err) {}
+static inline void blk_pre_runtime_resume(struct request_queue *q) {}
+static inline void blk_post_runtime_resume(struct request_queue *q, int err) {}
+#endif
+
+/*
  * blk_plug permits building a queue of related requests by holding the I/O
  * fragments for a short period. This allows merging of sequential requests
  * into single larger request. As the requests are moved from a per-task list to
-- 
1.7.11.7

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