PCI: qcom: Define some PARF params needed for ipq8064 SoC

Set some specific value for Tx De-Emphasis, Tx Swing and Rx equalization
needed on some ipq8064 based device (Netgear R7800 for example). Without
this the system locks on kernel load.

Link: https://lore.kernel.org/r/20200615210608.21469-8-ansuelsmth@gmail.com
Fixes: 82a823833f ("PCI: qcom: Add Qualcomm PCIe controller driver")
Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Stanimir Varbanov <svarbanov@mm-sol.com>
Cc: stable@vger.kernel.org # v4.5+

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

@@ -77,6 +77,18 @@
 #define DBI_RO_WR_EN				1
 
 #define PERST_DELAY_US				1000
+/* PARF registers */
+#define PCIE20_PARF_PCS_DEEMPH			0x34
+#define PCS_DEEMPH_TX_DEEMPH_GEN1(x)		((x) << 16)
+#define PCS_DEEMPH_TX_DEEMPH_GEN2_3_5DB(x)	((x) << 8)
+#define PCS_DEEMPH_TX_DEEMPH_GEN2_6DB(x)	((x) << 0)
+
+#define PCIE20_PARF_PCS_SWING			0x38
+#define PCS_SWING_TX_SWING_FULL(x)		((x) << 8)
+#define PCS_SWING_TX_SWING_LOW(x)		((x) << 0)
+
+#define PCIE20_PARF_CONFIG_BITS		0x50
+#define PHY_RX0_EQ(x)				((x) << 24)
 
 #define PCIE20_v3_PARF_SLV_ADDR_SPACE_SIZE	0x358
 #define SLV_ADDR_SPACE_SZ			0x10000000
@@ -293,6 +305,7 @@ static int qcom_pcie_init_2_1_0(struct qcom_pcie *pcie)
 	struct qcom_pcie_resources_2_1_0 *res = &pcie->res.v2_1_0;
 	struct dw_pcie *pci = pcie->pci;
 	struct device *dev = pci->dev;
+	struct device_node *node = dev->of_node;
 	u32 val;
 	int ret;
 
@@ -347,6 +360,17 @@ static int qcom_pcie_init_2_1_0(struct qcom_pcie *pcie)
 	val &= ~BIT(0);
 	writel(val, pcie->parf + PCIE20_PARF_PHY_CTRL);
 
+	if (of_device_is_compatible(node, "qcom,pcie-ipq8064")) {
+		writel(PCS_DEEMPH_TX_DEEMPH_GEN1(24) |
+			       PCS_DEEMPH_TX_DEEMPH_GEN2_3_5DB(24) |
+			       PCS_DEEMPH_TX_DEEMPH_GEN2_6DB(34),
+		       pcie->parf + PCIE20_PARF_PCS_DEEMPH);
+		writel(PCS_SWING_TX_SWING_FULL(120) |
+			       PCS_SWING_TX_SWING_LOW(120),
+		       pcie->parf + PCIE20_PARF_PCS_SWING);
+		writel(PHY_RX0_EQ(4), pcie->parf + PCIE20_PARF_CONFIG_BITS);
+	}
+
 	/* enable external reference clock */
 	val = readl(pcie->parf + PCIE20_PARF_PHY_REFCLK);
 	val |= BIT(16);