phy: tegra: Add PCIe PIPE2UPHY support for Tegra234

Synopsys DesignWare core based PCIe controllers in Tegra234 SoC
interface with Universal PHY (UPHY) module through a PIPE2UPHY (P2U)
module. For each PCIe lane of a controller, there is a P2U unit
instantiated at hardware level. This driver provides support for the
programming required for each P2U that is going to be used for a PCIe
controller.

Signed-off-by: Vidya Sagar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Vinod Koul <[email protected]>

drivers/phy/tegra/phy-tegra194-p2u.c

@@ -2,7 +2,7 @@
 /*
  * P2U (PIPE to UPHY) driver for Tegra T194 SoC
  *
- * Copyright (C) 2019 NVIDIA Corporation.
+ * Copyright (C) 2019-2022 NVIDIA Corporation.
  *
  * Author: Vidya Sagar <[email protected]>
  */
@@ -14,6 +14,9 @@
 #include <linux/of_platform.h>
 #include <linux/phy/phy.h>
 
+#define P2U_CONTROL_CMN			0x74
+#define P2U_CONTROL_CMN_SKP_SIZE_PROTECTION_EN			BIT(20)
+
 #define P2U_PERIODIC_EQ_CTRL_GEN3	0xc0
 #define P2U_PERIODIC_EQ_CTRL_GEN3_PERIODIC_EQ_EN		BIT(0)
 #define P2U_PERIODIC_EQ_CTRL_GEN3_INIT_PRESET_EQ_TRAIN_EN	BIT(1)
@@ -24,8 +27,17 @@
 #define P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_MASK	0xffff
 #define P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_VAL		160
 
+#define P2U_DIR_SEARCH_CTRL				0xd4
+#define P2U_DIR_SEARCH_CTRL_GEN4_FINE_GRAIN_SEARCH_TWICE	BIT(18)
+
+struct tegra_p2u_of_data {
+	bool one_dir_search;
+};
+
 struct tegra_p2u {
 	void __iomem *base;
+	bool skip_sz_protection_en; /* Needed to support two retimers */
+	struct tegra_p2u_of_data *of_data;
 };
 
 static inline void p2u_writel(struct tegra_p2u *phy, const u32 value,
@@ -44,6 +56,12 @@ static int tegra_p2u_power_on(struct phy *x)
 	struct tegra_p2u *phy = phy_get_drvdata(x);
 	u32 val;
 
+	if (phy->skip_sz_protection_en) {
+		val = p2u_readl(phy, P2U_CONTROL_CMN);
+		val |= P2U_CONTROL_CMN_SKP_SIZE_PROTECTION_EN;
+		p2u_writel(phy, val, P2U_CONTROL_CMN);
+	}
+
 	val = p2u_readl(phy, P2U_PERIODIC_EQ_CTRL_GEN3);
 	val &= ~P2U_PERIODIC_EQ_CTRL_GEN3_PERIODIC_EQ_EN;
 	val |= P2U_PERIODIC_EQ_CTRL_GEN3_INIT_PRESET_EQ_TRAIN_EN;
@@ -58,6 +76,12 @@ static int tegra_p2u_power_on(struct phy *x)
 	val |= P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_VAL;
 	p2u_writel(phy, val, P2U_RX_DEBOUNCE_TIME);
 
+	if (phy->of_data->one_dir_search) {
+		val = p2u_readl(phy, P2U_DIR_SEARCH_CTRL);
+		val &= ~P2U_DIR_SEARCH_CTRL_GEN4_FINE_GRAIN_SEARCH_TWICE;
+		p2u_writel(phy, val, P2U_DIR_SEARCH_CTRL);
+	}
+
 	return 0;
 }
 
@@ -77,10 +101,19 @@ static int tegra_p2u_probe(struct platform_device *pdev)
 	if (!phy)
 		return -ENOMEM;
 
+	phy->of_data =
+		(struct tegra_p2u_of_data *)of_device_get_match_data(dev);
+	if (!phy->of_data)
+		return -EINVAL;
+
 	phy->base = devm_platform_ioremap_resource_byname(pdev, "ctl");
 	if (IS_ERR(phy->base))
 		return PTR_ERR(phy->base);
 
+	phy->skip_sz_protection_en =
+		of_property_read_bool(dev->of_node,
+				      "nvidia,skip-sz-protect-en");
+
 	platform_set_drvdata(pdev, phy);
 
 	generic_phy = devm_phy_create(dev, NULL, &ops);
@@ -96,9 +129,22 @@ static int tegra_p2u_probe(struct platform_device *pdev)
 	return 0;
 }
 
+static const struct tegra_p2u_of_data tegra194_p2u_of_data = {
+	.one_dir_search = false,
+};
+
+static const struct tegra_p2u_of_data tegra234_p2u_of_data = {
+	.one_dir_search = true,
+};
+
 static const struct of_device_id tegra_p2u_id_table[] = {
 	{
 		.compatible = "nvidia,tegra194-p2u",
+		.data = &tegra194_p2u_of_data,
+	},
+	{
+		.compatible = "nvidia,tegra234-p2u",
+		.data = &tegra234_p2u_of_data,
 	},
 	{}
 };