linux-kernel - [PATCH V2 6/6] scsi: ufs: host : Introduce phy_power

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Message-ID: <20250318144944.19749-7-quic_nitirawa@quicinc.com>
Date: Tue, 18 Mar 2025 20:19:44 +0530
From: Nitin Rawat <quic_nitirawa@...cinc.com>
To: vkoul@...nel.org, kishon@...nel.org, manivannan.sadhasivam@...aro.org,
        James.Bottomley@...senPartnership.com, martin.petersen@...cle.com,
        konrad.dybcio@....qualcomm.com
Cc: quic_rdwivedi@...cinc.com, linux-arm-msm@...r.kernel.org,
        linux-phy@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-scsi@...r.kernel.org, Nitin Rawat <quic_nitirawa@...cinc.com>,
        Can Guo <quic_cang@...cinc.com>
Subject: [PATCH V2 6/6] scsi: ufs: host : Introduce phy_power_on/off wrapper function

Introduce ufs_qcom_phy_power_on and ufs_qcom_phy_power_off wrapper
functions with mutex protection to ensure safe usage of is_phy_pwr_on
and prevent possible race conditions.

Co-developed-by: Can Guo <quic_cang@...cinc.com>
Signed-off-by: Can Guo <quic_cang@...cinc.com>
Signed-off-by: Nitin Rawat <quic_nitirawa@...cinc.com>
---
 drivers/ufs/host/ufs-qcom.c | 44 +++++++++++++++++++++++++++++++------
 drivers/ufs/host/ufs-qcom.h |  4 ++++
 2 files changed, 41 insertions(+), 7 deletions(-)

diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
index 5c7b6c75d669..8f80724e64b9 100644
--- a/drivers/ufs/host/ufs-qcom.c
+++ b/drivers/ufs/host/ufs-qcom.c
@@ -421,6 +421,38 @@ static u32 ufs_qcom_get_hs_gear(struct ufs_hba *hba)
 	return UFS_HS_G3;
 }

+static int ufs_qcom_phy_power_on(struct ufs_hba *hba)
+{
+	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
+	struct phy *phy = host->generic_phy;
+	int ret = 0;
+
+	guard(mutex)(&host->phy_mutex);
+	if (!host->is_phy_pwr_on) {
+		ret = phy_power_on(phy);
+		if (!ret)
+			host->is_phy_pwr_on = true;
+	}
+
+	return ret;
+}
+
+static int ufs_qcom_phy_power_off(struct ufs_hba *hba)
+{
+	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
+	struct phy *phy = host->generic_phy;
+	int ret = 0;
+
+	guard(mutex)(&host->phy_mutex);
+	if (host->is_phy_pwr_on) {
+		ret = phy_power_off(phy);
+		if (!ret)
+			host->is_phy_pwr_on = false;
+	}
+
+	return ret;
+}
+
 static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
 {
 	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
@@ -449,7 +481,7 @@ static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
 		return ret;

 	if (phy->power_count) {
-		phy_power_off(phy);
+		ufs_qcom_phy_power_off(hba);
 		phy_exit(phy);
 	}

@@ -466,7 +498,7 @@ static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
 		goto out_disable_phy;

 	/* power on phy - start serdes and phy's power and clocks */
-	ret = phy_power_on(phy);
+	ret = ufs_qcom_phy_power_on(hba);
 	if (ret) {
 		dev_err(hba->dev, "%s: phy power on failed, ret = %d\n",
 			__func__, ret);
@@ -1017,7 +1049,6 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
 				 enum ufs_notify_change_status status)
 {
 	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
-	struct phy *phy = host->generic_phy;
 	int err;

 	/*
@@ -1037,7 +1068,7 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
 				/* disable device ref_clk */
 				ufs_qcom_dev_ref_clk_ctrl(host, false);
 			}
-			err = phy_power_off(phy);
+			err = ufs_qcom_phy_power_off(hba);
 			if (err) {
 				dev_err(hba->dev, "phy power off failed, ret=%d\n", err);
 					return err;
@@ -1046,7 +1077,7 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
 		break;
 	case POST_CHANGE:
 		if (on) {
-			err = phy_power_on(phy);
+			err = ufs_qcom_phy_power_on(hba);
 			if (err) {
 				dev_err(hba->dev, "phy power on failed, ret = %d\n", err);
 				return err;
@@ -1233,10 +1264,9 @@ static int ufs_qcom_init(struct ufs_hba *hba)
 static void ufs_qcom_exit(struct ufs_hba *hba)
 {
 	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
-	struct phy *phy = host->generic_phy;

 	ufs_qcom_disable_lane_clks(host);
-	phy_power_off(phy);
+	ufs_qcom_phy_power_off(hba);
 	phy_exit(host->generic_phy);
 }

diff --git a/drivers/ufs/host/ufs-qcom.h b/drivers/ufs/host/ufs-qcom.h
index d0e6ec9128e7..3db29fbcd40b 100644
--- a/drivers/ufs/host/ufs-qcom.h
+++ b/drivers/ufs/host/ufs-qcom.h
@@ -252,6 +252,10 @@ struct ufs_qcom_host {
 	u32 phy_gear;

 	bool esi_enabled;
+	/* flag to check if phy is powered on */
+	bool is_phy_pwr_on;
+	/* Protect the usage of is_phy_pwr_on against racing */
+	struct mutex phy_mutex;
 };

 struct ufs_qcom_drvdata {
--
2.48.1