PCI: qcom: Allow ASPM L1 and substates for 2.7.0

Allow ASPM L1 and its substates.  By default this is disabled in the qcom
specific hardware.  Enable it explicitly only for controllers belonging to
2_7_0.

This does not affect any link capability registers; it will allow the link
transitions to L1 and its substates only if they are already supported.

Link: https://lore.kernel.org/r/1657886366-32685-1-git-send-email-quic_krichai@quicinc.comSigned-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Acked-by: Stanimir Varbanov <svarbanov@mm-sol.com>

drivers/pci/controller/dwc/pcie-qcom.c

@@ -41,6 +41,9 @@
 #define L23_CLK_RMV_DIS				BIT(2)
 #define L1_CLK_RMV_DIS				BIT(1)
 
+#define PCIE20_PARF_PM_CTRL			0x20
+#define REQ_NOT_ENTR_L1				BIT(5)
+
 #define PCIE20_PARF_PHY_CTRL			0x40
 #define PHY_CTRL_PHY_TX0_TERM_OFFSET_MASK	GENMASK(20, 16)
 #define PHY_CTRL_PHY_TX0_TERM_OFFSET(x)		((x) << 16)
@@ -1265,6 +1268,11 @@ static int qcom_pcie_init_2_7_0(struct qcom_pcie *pcie)
 	val |= BIT(4);
 	writel(val, pcie->parf + PCIE20_PARF_MHI_CLOCK_RESET_CTRL);
 
+	/* Enable L1 and L1SS */
+	val = readl(pcie->parf + PCIE20_PARF_PM_CTRL);
+	val &= ~REQ_NOT_ENTR_L1;
+	writel(val, pcie->parf + PCIE20_PARF_PM_CTRL);
+
 	if (IS_ENABLED(CONFIG_PCI_MSI)) {
 		val = readl(pcie->parf + PCIE20_PARF_AXI_MSTR_WR_ADDR_HALT);
 		val |= BIT(31);