linux-kernel - [PATCH v4 06/12] PCI: qcom-ep: Gate Master AXI clock to MHI bus during L1SS

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Message-Id: <20220914075350.7992-7-manivannan.sadhasivam@linaro.org>
Date:   Wed, 14 Sep 2022 13:23:44 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     lpieralisi@...nel.org, robh@...nel.org, andersson@...nel.org
Cc:     kw@...ux.com, bhelgaas@...gle.com, linux-pci@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        konrad.dybcio@...ainline.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, devicetree@...r.kernel.org,
        dmitry.baryshkov@...aro.org,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Subject: [PATCH v4 06/12] PCI: qcom-ep: Gate Master AXI clock to MHI bus during L1SS

During L1SS, gate the Master clock supplied to the MHI bus to save power.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
---
 drivers/pci/controller/dwc/pcie-qcom-ep.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
index 2dc6d4e44aff..526e98ea23f6 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
@@ -27,6 +27,7 @@
 #define PARF_SYS_CTRL				0x00
 #define PARF_DB_CTRL				0x10
 #define PARF_PM_CTRL				0x20
+#define PARF_MHI_CLOCK_RESET_CTRL		0x174
 #define PARF_MHI_BASE_ADDR_LOWER		0x178
 #define PARF_MHI_BASE_ADDR_UPPER		0x17c
 #define PARF_DEBUG_INT_EN			0x190
@@ -89,6 +90,9 @@
 #define PARF_PM_CTRL_READY_ENTR_L23		BIT(2)
 #define PARF_PM_CTRL_REQ_NOT_ENTR_L1		BIT(5)
 
+/* PARF_MHI_CLOCK_RESET_CTRL fields */
+#define PARF_MSTR_AXI_CLK_EN			BIT(1)
+
 /* PARF_AXI_MSTR_RD_HALT_NO_WRITES register fields */
 #define PARF_AXI_MSTR_RD_HALT_NO_WRITE_EN	BIT(0)
 
@@ -394,6 +398,11 @@ static int qcom_pcie_perst_deassert(struct dw_pcie *pci)
 		       pcie_ep->parf + PARF_MHI_BASE_ADDR_LOWER);
 	writel_relaxed(0, pcie_ep->parf + PARF_MHI_BASE_ADDR_UPPER);
 
+	/* Gate Master AXI clock to MHI bus during L1SS */
+	val = readl_relaxed(pcie_ep->parf + PARF_MHI_CLOCK_RESET_CTRL);
+	val &= ~PARF_MSTR_AXI_CLK_EN;
+	val = readl_relaxed(pcie_ep->parf + PARF_MHI_CLOCK_RESET_CTRL);
+
 	dw_pcie_ep_init_notify(&pcie_ep->pci.ep);
 
 	/* Enable LTSSM */
-- 
2.25.1