[PATCH v8 10/12] phy: qcom: qmp-usbc: Add USB/DP exclude handling

[Xiangxu Yin via B4 Relay <devnull+xiangxu.yin.oss.qualcomm.com@kernel.org>]

From: Xiangxu Yin <xiangxu.yin@oss.qualcomm.com>

When both USB and DP PHY modes are enabled simultaneously on the same
QMP USBC PHY, it can lead to hardware misconfiguration and undefined
behavior. This happens because the PHY resources are not designed to
operate in both modes at the same time.

To prevent this, introduce a mutual exclusion check between USB and DP
PHY modes.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Xiangxu Yin <xiangxu.yin@oss.qualcomm.com>
---
 drivers/phy/qualcomm/phy-qcom-qmp-usbc.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-usbc.c b/drivers/phy/qualcomm/phy-qcom-qmp-usbc.c
index 1ac755825313..b1a2380401ff 100644
--- a/drivers/phy/qualcomm/phy-qcom-qmp-usbc.c
+++ b/drivers/phy/qualcomm/phy-qcom-qmp-usbc.c
@@ -666,6 +666,19 @@ static int qmp_usbc_usb_power_off(struct phy *phy)
 	return 0;
 }
 
+static int qmp_usbc_check_phy_status(struct qmp_usbc *qmp, bool is_dp)
+{
+	if ((is_dp && qmp->usb_init_count) ||
+	    (!is_dp && qmp->dp_init_count)) {
+		dev_err(qmp->dev,
+			"PHY is configured for %s, can not enable %s\n",
+			is_dp ? "USB" : "DP", is_dp ? "DP" : "USB");
+		return -EBUSY;
+	}
+
+	return 0;
+}
+
 static int qmp_usbc_usb_enable(struct phy *phy)
 {
 	struct qmp_usbc *qmp = phy_get_drvdata(phy);
@@ -673,6 +686,10 @@ static int qmp_usbc_usb_enable(struct phy *phy)
 
 	mutex_lock(&qmp->phy_mutex);
 
+	ret = qmp_usbc_check_phy_status(qmp, false);
+	if (ret)
+		goto out_unlock;
+
 	ret = qmp_usbc_com_init(phy);
 	if (ret)
 		goto out_unlock;
@@ -726,6 +743,10 @@ static int qmp_usbc_dp_enable(struct phy *phy)
 
 	mutex_lock(&qmp->phy_mutex);
 
+	ret = qmp_usbc_check_phy_status(qmp, true);
+	if (ret)
+		goto dp_init_unlock;
+
 	ret = qmp_usbc_com_init(phy);
 	if (ret)
 		goto dp_init_unlock;

-- 
2.34.1