[PATCH v4 3/5] PCI: qcom: Power down PHY via PARF_PHY_CTRL before disabling rails/clocks

[Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>]

Some Qcom PCIe controller variants bring the PHY out of test power-down
(PHY_TEST_PWR_DOWN) during init. When the link is later transitioned
towards D3cold and the driver disables PCIe clocks and/or regulators
without explicitly re-asserting PHY_TEST_PWR_DOWN, the PHY can remain
partially powered, leading to avoidable power leakage.

Update the init-path comments to reflect that PARF_PHY_CTRL is used to
power the PHY on. Also, for controller revisions that enable PHY power
in init (2.3.2, 2.3.3, 2.7.0 and 2.9.0), explicitly power the PHY down
via PARF_PHY_CTRL in the deinit path before disabling clocks/regulators.

This ensures the PHY is put into a defined low-power state prior to
removing its supplies, preventing leakage when entering D3cold.

Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 32 +++++++++++++++++++++++++++++---
 1 file changed, 29 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index b00bf46637a5ff803a845719c5b0b5b82739244b..c14c3eb70f356b6ad8a2ffe48b107327d2babf77 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -513,7 +513,7 @@ static int qcom_pcie_post_init_2_1_0(struct qcom_pcie *pcie)
 	u32 val;
 	int ret;
 
-	/* enable PCIe clocks and resets */
+	/* Force PHY out of lowest power state */
 	val = readl(pcie->parf + PARF_PHY_CTRL);
 	val &= ~PHY_TEST_PWR_DOWN;
 	writel(val, pcie->parf + PARF_PHY_CTRL);
@@ -680,6 +680,12 @@ static int qcom_pcie_get_resources_2_3_2(struct qcom_pcie *pcie)
 static void qcom_pcie_deinit_2_3_2(struct qcom_pcie *pcie)
 {
 	struct qcom_pcie_resources_2_3_2 *res = &pcie->res.v2_3_2;
+	u32 val;
+
+	/* Force PHY to lowest power state*/
+	val = readl(pcie->parf + PARF_PHY_CTRL);
+	val |= PHY_TEST_PWR_DOWN;
+	writel(val, pcie->parf + PARF_PHY_CTRL);
 
 	clk_bulk_disable_unprepare(res->num_clks, res->clks);
 	regulator_bulk_disable(ARRAY_SIZE(res->supplies), res->supplies);
@@ -712,7 +718,7 @@ static int qcom_pcie_post_init_2_3_2(struct qcom_pcie *pcie)
 {
 	u32 val;
 
-	/* enable PCIe clocks and resets */
+	/* Force PHY out of lowest power state */
 	val = readl(pcie->parf + PARF_PHY_CTRL);
 	val &= ~PHY_TEST_PWR_DOWN;
 	writel(val, pcie->parf + PARF_PHY_CTRL);
@@ -844,6 +850,12 @@ static int qcom_pcie_get_resources_2_3_3(struct qcom_pcie *pcie)
 static void qcom_pcie_deinit_2_3_3(struct qcom_pcie *pcie)
 {
 	struct qcom_pcie_resources_2_3_3 *res = &pcie->res.v2_3_3;
+	u32 val;
+
+	/* Force PHY to lowest power state */
+	val = readl(pcie->parf + PARF_PHY_CTRL);
+	val |= PHY_TEST_PWR_DOWN;
+	writel(val, pcie->parf + PARF_PHY_CTRL);
 
 	clk_bulk_disable_unprepare(res->num_clks, res->clks);
 }
@@ -899,6 +911,7 @@ static int qcom_pcie_post_init_2_3_3(struct qcom_pcie *pcie)
 	u16 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
 	u32 val;
 
+	/* Force PHY out of lowest power state */
 	val = readl(pcie->parf + PARF_PHY_CTRL);
 	val &= ~PHY_TEST_PWR_DOWN;
 	writel(val, pcie->parf + PARF_PHY_CTRL);
@@ -994,7 +1007,7 @@ static int qcom_pcie_init_2_7_0(struct qcom_pcie *pcie)
 	/* configure PCIe to RC mode */
 	writel(DEVICE_TYPE_RC, pcie->parf + PARF_DEVICE_TYPE);
 
-	/* enable PCIe clocks and resets */
+	/* Force PHY out of lowest power state */
 	val = readl(pcie->parf + PARF_PHY_CTRL);
 	val &= ~PHY_TEST_PWR_DOWN;
 	writel(val, pcie->parf + PARF_PHY_CTRL);
@@ -1065,6 +1078,12 @@ static void qcom_pcie_host_post_init_2_7_0(struct qcom_pcie *pcie)
 static void qcom_pcie_deinit_2_7_0(struct qcom_pcie *pcie)
 {
 	struct qcom_pcie_resources_2_7_0 *res = &pcie->res.v2_7_0;
+	u32 val;
+
+	/* Force PHY to lowest power state */
+	val = readl(pcie->parf + PARF_PHY_CTRL);
+	val |= PHY_TEST_PWR_DOWN;
+	writel(val, pcie->parf + PARF_PHY_CTRL);
 
 	clk_bulk_disable_unprepare(res->num_clks, res->clks);
 
@@ -1169,6 +1188,12 @@ static int qcom_pcie_get_resources_2_9_0(struct qcom_pcie *pcie)
 static void qcom_pcie_deinit_2_9_0(struct qcom_pcie *pcie)
 {
 	struct qcom_pcie_resources_2_9_0 *res = &pcie->res.v2_9_0;
+	u32 val;
+
+	/* Force PHY to lowest power state */
+	val = readl(pcie->parf + PARF_PHY_CTRL);
+	val |= PHY_TEST_PWR_DOWN;
+	writel(val, pcie->parf + PARF_PHY_CTRL);
 
 	clk_bulk_disable_unprepare(res->num_clks, res->clks);
 }
@@ -1209,6 +1234,7 @@ static int qcom_pcie_post_init_2_9_0(struct qcom_pcie *pcie)
 	u32 val;
 	int i;
 
+	/* Force PHY out of lowest power state */
 	val = readl(pcie->parf + PARF_PHY_CTRL);
 	val &= ~PHY_TEST_PWR_DOWN;
 	writel(val, pcie->parf + PARF_PHY_CTRL);

-- 
2.34.1