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.

Link: https://lore.kernel.org/r/20220914075350.7992-7-manivannan.sadhasivam@linaro.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>

diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
index d4f2437..5502e62 100644 (file)
--- 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 */