PCI: qcom: Add support for tx term offset for rev 2.1.0

Add tx term offset support to pcie qcom driver need in some revision of
the ipq806x SoC. Ipq8064 needs tx term offset set to 7.

Link: https://lore.kernel.org/r/[email protected]
Fixes: 82a8238 ("PCI: qcom: Add Qualcomm PCIe controller driver")
Signed-off-by: Sham Muthayyan <[email protected]>
Signed-off-by: Ansuel Smith <[email protected]>
Signed-off-by: Lorenzo Pieralisi <[email protected]>
Acked-by: Stanimir Varbanov <[email protected]>
Cc: [email protected] # v4.5+

Author: Ansuel

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

@@ -45,7 +45,13 @@
 #define PCIE_CAP_CPL_TIMEOUT_DISABLE		0x10
 
 #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)
+
 #define PCIE20_PARF_PHY_REFCLK			0x4C
+#define PHY_REFCLK_SSP_EN			BIT(16)
+#define PHY_REFCLK_USE_PAD			BIT(12)
+
 #define PCIE20_PARF_DBI_BASE_ADDR		0x168
 #define PCIE20_PARF_SLV_ADDR_SPACE_SIZE		0x16C
 #define PCIE20_PARF_MHI_CLOCK_RESET_CTRL	0x174
@@ -371,9 +377,18 @@ static int qcom_pcie_init_2_1_0(struct qcom_pcie *pcie)
 		writel(PHY_RX0_EQ(4), pcie->parf + PCIE20_PARF_CONFIG_BITS);
 	}
 
+	if (of_device_is_compatible(node, "qcom,pcie-ipq8064")) {
+		/* set TX termination offset */
+		val = readl(pcie->parf + PCIE20_PARF_PHY_CTRL);
+		val &= ~PHY_CTRL_PHY_TX0_TERM_OFFSET_MASK;
+		val |= PHY_CTRL_PHY_TX0_TERM_OFFSET(7);
+		writel(val, pcie->parf + PCIE20_PARF_PHY_CTRL);
+	}
+
 	/* enable external reference clock */
 	val = readl(pcie->parf + PCIE20_PARF_PHY_REFCLK);
-	val |= BIT(16);
+	val &= ~PHY_REFCLK_USE_PAD;
+	val |= PHY_REFCLK_SSP_EN;
 	writel(val, pcie->parf + PCIE20_PARF_PHY_REFCLK);
 
 	/* wait for clock acquisition */