[PATCH v4 4/7] scsi: ufs: wb: Add explicit flush sysfs attribute

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

There is the following quirk to bypass "WB 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 Flush".

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

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

Reviewed-by: Avri Altman <avri.altman@xxxxxxx>
Signed-off-by: Jinyoung Choi <j-young.choi@xxxxxxxxxxx>
---
 drivers/ufs/core/ufs-sysfs.c | 45 ++++++++++++++++++++++++++++++++++++
 drivers/ufs/core/ufshcd.c    |  9 ++++----
 include/ufs/ufshcd.h         |  1 +
 3 files changed, 51 insertions(+), 4 deletions(-)

diff --git a/drivers/ufs/core/ufs-sysfs.c b/drivers/ufs/core/ufs-sysfs.c
index 0a088b47d557..e7800e49998a 100644
--- a/drivers/ufs/core/ufs-sysfs.c
+++ b/drivers/ufs/core/ufs-sysfs.c
@@ -254,6 +254,49 @@ 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_allowed(hba) &&
+	   !(hba->quirks & UFSHCI_QUIRK_SKIP_MANUAL_WB_FLUSH_CTRL)) {
+		dev_warn(dev, "It is not allowed to configure 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 +305,7 @@ 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 +316,7 @@ 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
 };
 
diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 52377fedae49..a8a797e0033d 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -267,7 +267,6 @@ static inline int ufshcd_config_vreg_hpm(struct ufs_hba *hba,
 static int ufshcd_try_to_abort_task(struct ufs_hba *hba, int tag);
 static void ufshcd_wb_toggle_buf_flush_during_h8(struct ufs_hba *hba,
 						 bool enable);
-static void ufshcd_wb_toggle_buf_flush(struct ufs_hba *hba, bool enable);
 static void ufshcd_hba_vreg_set_lpm(struct ufs_hba *hba);
 static void ufshcd_hba_vreg_set_hpm(struct ufs_hba *hba);
 
@@ -5767,24 +5766,26 @@ static void ufshcd_wb_toggle_buf_flush_during_h8(struct ufs_hba *hba,
 			__func__, enable ? "enabled" : "disabled");
 }
 
-static void ufshcd_wb_toggle_buf_flush(struct ufs_hba *hba, bool enable)
+int ufshcd_wb_toggle_buf_flush(struct ufs_hba *hba, bool enable)
 {
 	int ret;
 
 	if (hba->dev_info.wb_buf_flush_enabled == enable)
-		return;
+		return 0;
 
 	ret = __ufshcd_wb_toggle(hba, enable, QUERY_FLAG_IDN_WB_BUFF_FLUSH_EN);
 	if (ret) {
 		dev_err(hba->dev, "%s WB-Buf Flush %s failed %d\n", __func__,
 			enable ? "enable" : "disable", ret);
-		return;
+		return ret;
 	}
 
 	hba->dev_info.wb_buf_flush_enabled = enable;
 
 	dev_dbg(hba->dev, "%s WB-Buf Flush %s\n",
 			__func__, enable ? "enabled" : "disabled");
+
+	return ret;
 }
 
 static bool ufshcd_wb_presrv_usrspc_keep_vcc_on(struct ufs_hba *hba,
diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index 7fe1a926cd99..94bcfec98fb8 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -1211,6 +1211,7 @@ int ufshcd_exec_raw_upiu_cmd(struct ufs_hba *hba,
 			     enum query_opcode desc_op);
 
 int ufshcd_wb_toggle(struct ufs_hba *hba, bool enable);
+int ufshcd_wb_toggle_buf_flush(struct ufs_hba *hba, bool enable);
 int ufshcd_suspend_prepare(struct device *dev);
 int __ufshcd_suspend_prepare(struct device *dev, bool rpm_ok_for_spm);
 void ufshcd_resume_complete(struct device *dev);
-- 
2.25.1