[PATCH v3 04/12] scsi: ufs: Add sysfs node to dynamically control clock gating

Subhash Jadavani
2016-12-23T02:40:48Z

From: Sahitya Tummala <stummala@codeaurora.org>

Provide an option to enable/disable clock gating during runtime.
Write 1 or 0 to "clkgate_enable" sysfs node to enable/disable
clock gating.

Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
---
drivers/scsi/ufs/ufshcd.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++-
drivers/scsi/ufs/ufshcd.h | 4 ++++
2 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 2e7c172..2ed82c2 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -970,6 +970,41 @@ static ssize_t ufshcd_clkgate_delay_store(struct device *dev,
return count;
}

+static ssize_t ufshcd_clkgate_enable_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct ufs_hba *hba = dev_get_drvdata(dev);
+
+ return snprintf(buf, PAGE_SIZE, "%d\n", hba->clk_gating.is_enabled);
+}
+
+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);
+ unsigned long flags;
+ u32 value;
+
+ if (kstrtou32(buf, 0, &value))
+ return -EINVAL;
+
+ value = !!value;
+ if (value == hba->clk_gating.is_enabled)
+ goto out;
+
+ if (value) {
+ ufshcd_release(hba);
+ } else {
+ spin_lock_irqsave(hba->host->host_lock, flags);
+ hba->clk_gating.active_reqs++;
+ spin_unlock_irqrestore(hba->host->host_lock, flags);
+ }
+
+ hba->clk_gating.is_enabled = value;
+out:
+ return count;
+}
+
static void ufshcd_init_clk_gating(struct ufs_hba *hba)
{
if (!ufshcd_is_clkgating_allowed(hba))
@@ -979,13 +1014,23 @@ static void ufshcd_init_clk_gating(struct ufs_hba *hba)
INIT_DELAYED_WORK(&hba->clk_gating.gate_work, ufshcd_gate_work);
INIT_WORK(&hba->clk_gating.ungate_work, ufshcd_ungate_work);

+ hba->clk_gating.is_enabled = true;
+
hba->clk_gating.delay_attr.show = ufshcd_clkgate_delay_show;
hba->clk_gating.delay_attr.store = ufshcd_clkgate_delay_store;
sysfs_attr_init(&hba->clk_gating.delay_attr.attr);
hba->clk_gating.delay_attr.attr.name = "clkgate_delay_ms";
- hba->clk_gating.delay_attr.attr.mode = S_IRUGO | S_IWUSR;
+ hba->clk_gating.delay_attr.attr.mode = 0644;
if (device_create_file(hba->dev, &hba->clk_gating.delay_attr))
dev_err(hba->dev, "Failed to create sysfs for clkgate_delay\n");
+
+ hba->clk_gating.enable_attr.show = ufshcd_clkgate_enable_show;
+ hba->clk_gating.enable_attr.store = ufshcd_clkgate_enable_store;
+ sysfs_attr_init(&hba->clk_gating.enable_attr.attr);
+ hba->clk_gating.enable_attr.attr.name = "clkgate_enable";
+ hba->clk_gating.enable_attr.attr.mode = 0644;
+ if (device_create_file(hba->dev, &hba->clk_gating.enable_attr))
+ dev_err(hba->dev, "Failed to create sysfs for clkgate_enable\n");
}

static void ufshcd_exit_clk_gating(struct ufs_hba *hba)
@@ -993,6 +1038,7 @@ static void ufshcd_exit_clk_gating(struct ufs_hba *hba)
if (!ufshcd_is_clkgating_allowed(hba))
return;
device_remove_file(hba->dev, &hba->clk_gating.delay_attr);
+ device_remove_file(hba->dev, &hba->clk_gating.enable_attr);
cancel_work_sync(&hba->clk_gating.ungate_work);
cancel_delayed_work_sync(&hba->clk_gating.gate_work);
}
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 08cd26e..0882ba6 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -320,6 +320,8 @@ enum clk_gating_state {
* @is_suspended: clk gating is suspended when set to 1 which can be used
* during suspend/resume
* @delay_attr: sysfs attribute to control delay_attr
+ * @enable_attr: sysfs attribute to enable/disable clock gating
+ * @is_enabled: Indicates the current status of clock gating
* @active_reqs: number of requests that are pending and should be waited for
* completion before gating clocks.
*/
@@ -330,6 +332,8 @@ struct ufs_clk_gating {
unsigned long delay_ms;
bool is_suspended;
struct device_attribute delay_attr;
+ struct device_attribute enable_attr;
+ bool is_enabled;
int active_reqs;
};

--
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