[PATCH 3/7] ufs: core: Redirect clock gating to RPM

[Bart Van Assche <bvanassche@acm.org>]

Let the clkgate_enable and clkgate_delay_ms sysfs attributes control
runtime power management instead of clock gating. Enable runtime power
management if either UFSHCD_CAP_RPM_AUTOSUSPEND or UFSHCD_CAP_CLK_GATING
have been set.

This patch prepares for removing the clock gating code because:
- The functionality of the clock gating code is identical to the runtime
  power management code. Both track the number of SCSI commands that are in
  progress, gate clocks, disable VCC and VCCQ and trigger link hibernation
  after a delay if no commands are in progress.
- The runtime power management code is more efficient because it uses a
  per-CPU counter while the clock gating code uses a single counter that
  is protected by a spinlock. Every spinlock in the I/O path has a
  measurable performance impact. Additionally, the clock gating code
  sets the BLK_MQ_F_BLOCKING flag for all SCSI request queues. This flag
  increases the amount of time spent in the block layer on processing
  requests.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/ufs/core/ufshcd.c | 49 +++++++++++++++++++++++++--------------
 include/ufs/ufshcd.h      |  2 +-
 2 files changed, 32 insertions(+), 19 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 2ee1947af797..900b945444d1 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -2107,18 +2107,31 @@ void ufshcd_release(struct ufs_hba *hba)
 }
 EXPORT_SYMBOL_GPL(ufshcd_release);
 
+/* The struct device instance that controls RPM for the UFS device. */
+static inline struct device *ufs_rpm_dev(struct ufs_hba *hba)
+{
+	return &hba->ufs_device_wlun->sdev_gendev;
+}
+
 static ssize_t ufshcd_clkgate_delay_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct ufs_hba *hba = dev_get_drvdata(dev);
+	struct device *rpm_dev = ufs_rpm_dev(hba);
 
-	return sysfs_emit(buf, "%lu\n", hba->clk_gating.delay_ms);
+	if (!rpm_dev->power.use_autosuspend)
+		return -EIO;
+
+	return sysfs_emit(buf, "%u\n", rpm_dev->power.autosuspend_delay);
 }
 
 void ufshcd_clkgate_delay_set(struct ufs_hba *hba, unsigned long value)
 {
-	guard(spinlock_irqsave)(&hba->clk_gating.lock);
-	hba->clk_gating.delay_ms = value;
+	struct device *rpm_dev = ufs_rpm_dev(hba);
+
+	device_lock(rpm_dev);
+	pm_runtime_set_autosuspend_delay(rpm_dev, value);
+	device_unlock(rpm_dev);
 }
 EXPORT_SYMBOL_GPL(ufshcd_clkgate_delay_set);
 
@@ -2126,8 +2139,12 @@ static ssize_t ufshcd_clkgate_delay_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t count)
 {
 	struct ufs_hba *hba = dev_get_drvdata(dev);
+	struct device *rpm_dev = ufs_rpm_dev(hba);
 	unsigned long value;
 
+	if (!rpm_dev->power.use_autosuspend)
+		return -EIO;
+
 	if (kstrtoul(buf, 0, &value))
 		return -EINVAL;
 
@@ -2140,31 +2157,27 @@ static ssize_t ufshcd_clkgate_enable_show(struct device *dev,
 {
 	struct ufs_hba *hba = dev_get_drvdata(dev);
 
-	return sysfs_emit(buf, "%d\n", hba->clk_gating.is_enabled);
+	return sysfs_emit(buf, "%d\n", ufs_rpm_dev(hba)->power.runtime_auto);
 }
 
 static ssize_t ufshcd_clkgate_enable_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t count)
 {
 	struct ufs_hba *hba = dev_get_drvdata(dev);
-	u32 value;
-
-	if (kstrtou32(buf, 0, &value))
-		return -EINVAL;
-
-	value = !!value;
-
-	guard(spinlock_irqsave)(&hba->clk_gating.lock);
+	struct device *rpm_dev = ufs_rpm_dev(hba);
+	bool value;
+	int err;
 
-	if (value == hba->clk_gating.is_enabled)
-		return count;
+	err = kstrtobool(buf, &value);
+	if (err)
+		return err;
 
+	device_lock(rpm_dev);
 	if (value)
-		__ufshcd_release(hba);
+		pm_runtime_allow(rpm_dev);
 	else
-		hba->clk_gating.active_reqs++;
-
-	hba->clk_gating.is_enabled = value;
+		pm_runtime_forbid(rpm_dev);
+	device_unlock(rpm_dev);
 
 	return count;
 }
diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index b4aef7acd351..dac07a5cd998 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -1224,7 +1224,7 @@ static inline bool ufshcd_can_autobkops_during_suspend(struct ufs_hba *hba)
 }
 static inline bool ufshcd_is_rpm_autosuspend_allowed(struct ufs_hba *hba)
 {
-	return hba->caps & UFSHCD_CAP_RPM_AUTOSUSPEND;
+	return hba->caps & (UFSHCD_CAP_RPM_AUTOSUSPEND | UFSHCD_CAP_CLK_GATING);
 }
 
 static inline bool ufshcd_is_intr_aggr_allowed(struct ufs_hba *hba)