[PATCH v3 2/2] scsi: ufs: wb: Add Manual Flush sysfs

[Jinyoung CHOI <j-young.choi@xxxxxxxxxxx>]

There is the following quirk to bypass "WB Manual Flush" in Write Booster.

	- UFSHCI_QUIRK_SKIP_MANUAL_WB_FLUSH_CTRL

If this quirk is not set, there is no knob that can control "WB Manual Flush".

There are three flags that control Write Booster Feature.
	1. WB ON/OFF
	2. WB Hibern Flush ON/OFF
	3. WB Flush ON/OFF

The sysfs that controls the WB was implemented. (1)

In the case of "Hibern Flush", it is always good to turn on.
Control may not be required. (2)

Finally, "Manual flush" may be necessary because the Auto-Hibern8 is not
supported in a specific environment.
So the sysfs that controls this is necessary. (3)

Signed-off-by: Jinyoung Choi <j-young.choi@xxxxxxxxxxx>
---
 drivers/ufs/core/ufs-sysfs.c | 44 ++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/drivers/ufs/core/ufs-sysfs.c b/drivers/ufs/core/ufs-sysfs.c
index 6253606b93b4..b1c51d8df9f4 100644
--- a/drivers/ufs/core/ufs-sysfs.c
+++ b/drivers/ufs/core/ufs-sysfs.c
@@ -254,6 +254,48 @@ static ssize_t wb_on_store(struct device *dev, struct device_attribute *attr,
 	return res < 0 ? res : count;
 }
 
+static ssize_t wb_buf_flush_en_show(struct device *dev,
+				    struct device_attribute *attr,
+				    char *buf)
+{
+	struct ufs_hba *hba = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%d\n", hba->dev_info.wb_buf_flush_enabled);
+}
+
+static ssize_t wb_buf_flush_en_store(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, size_t count)
+{
+	struct ufs_hba *hba = dev_get_drvdata(dev);
+	unsigned int wb_buf_flush_en;
+	ssize_t res;
+
+	if (!ufshcd_is_wb_buf_flush_allowed(hba)) {
+		dev_warn(dev, "It is not allowed to control WB buf flush!\n");
+		return -EOPNOTSUPP;
+	}
+
+	if (kstrtouint(buf, 0, &wb_buf_flush_en))
+		return -EINVAL;
+
+	if (wb_buf_flush_en != 0 && wb_buf_flush_en != 1)
+		return -EINVAL;
+
+	down(&hba->host_sem);
+	if (!ufshcd_is_user_access_allowed(hba)) {
+		res = -EBUSY;
+		goto out;
+	}
+
+	ufshcd_rpm_get_sync(hba);
+	res = ufshcd_wb_toggle_buf_flush(hba, wb_buf_flush_en);
+	ufshcd_rpm_put_sync(hba);
+out:
+	up(&hba->host_sem);
+	return res < 0 ? res : count;
+}
+
 static DEVICE_ATTR_RW(rpm_lvl);
 static DEVICE_ATTR_RO(rpm_target_dev_state);
 static DEVICE_ATTR_RO(rpm_target_link_state);
@@ -262,6 +304,7 @@ static DEVICE_ATTR_RO(spm_target_dev_state);
 static DEVICE_ATTR_RO(spm_target_link_state);
 static DEVICE_ATTR_RW(auto_hibern8);
 static DEVICE_ATTR_RW(wb_on);
+static DEVICE_ATTR_RW(wb_buf_flush_en);
 
 static struct attribute *ufs_sysfs_ufshcd_attrs[] = {
 	&dev_attr_rpm_lvl.attr,
@@ -272,6 +315,7 @@ static struct attribute *ufs_sysfs_ufshcd_attrs[] = {
 	&dev_attr_spm_target_link_state.attr,
 	&dev_attr_auto_hibern8.attr,
 	&dev_attr_wb_on.attr,
+	&dev_attr_wb_buf_flush_en.attr,
 	NULL
 };
 
-- 
2.25.1