PCI: rcar-gen4: Add support for R-Car V4H

Add support for r8a779g0 (R-Car V4H).

This driver previously supported r8a779f0 (R-Car S4-8). PCIe features
of both r8a779f0 and r8a779g0 are almost all the same. For example:

 - PCI Express Base Specification Revision 4.0
 - Root complex mode and endpoint mode are supported

However, r8a779g0 requires specific firmware to be provided, to
initialize the PHY. Otherwise, the PCIe controller will not work.

[kwilczynski: drop the proprietary firmware conversion comment]
Link: https://lore.kernel.org/linux-pci/20240611125057.1232873-5-yoshihiro.shimoda.uh@renesas.com
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

drivers/pci/controller/dwc/pcie-rcar-gen4.c

@@ -2,11 +2,17 @@
 /*
  * PCIe controller driver for Renesas R-Car Gen4 Series SoCs
  * Copyright (C) 2022-2023 Renesas Electronics Corporation
+ *
+ * The r8a779g0 (R-Car V4H) controller requires a specific firmware to be
+ * provided, to initialize the PHY. Otherwise, the PCIe controller will not
+ * work.
  */
 
 #include <linux/delay.h>
+#include <linux/firmware.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/pci.h>
@@ -20,9 +26,10 @@
 /* Renesas-specific */
 /* PCIe Mode Setting Register 0 */
 #define PCIEMSR0		0x0000
-#define BIFUR_MOD_SET_ON	BIT(0)
+#define APP_SRIS_MODE		BIT(6)
 #define DEVICE_TYPE_EP		0
 #define DEVICE_TYPE_RC		BIT(4)
+#define BIFUR_MOD_SET_ON	BIT(0)
 
 /* PCIe Interrupt Status 0 */
 #define PCIEINTSTS0		0x0084
@@ -37,19 +44,35 @@
 #define PCIEDMAINTSTSEN		0x0314
 #define PCIEDMAINTSTSEN_INIT	GENMASK(15, 0)
 
+/* Port Logic Registers 89 */
+#define PRTLGC89		0x0b70
+
+/* Port Logic Registers 90 */
+#define PRTLGC90		0x0b74
+
 /* PCIe Reset Control Register 1 */
 #define PCIERSTCTRL1		0x0014
 #define APP_HOLD_PHY_RST	BIT(16)
 #define APP_LTSSM_ENABLE	BIT(0)
 
+/* PCIe Power Management Control */
+#define PCIEPWRMNGCTRL		0x0070
+#define APP_CLK_REQ_N		BIT(11)
+#define APP_CLK_PM_EN		BIT(10)
+
 #define RCAR_NUM_SPEED_CHANGE_RETRIES	10
 #define RCAR_MAX_LINK_SPEED		4
 
 #define RCAR_GEN4_PCIE_EP_FUNC_DBI_OFFSET	0x1000
 #define RCAR_GEN4_PCIE_EP_FUNC_DBI2_OFFSET	0x800
 
+#define RCAR_GEN4_PCIE_FIRMWARE_NAME		"rcar_gen4_pcie.bin"
+#define RCAR_GEN4_PCIE_FIRMWARE_BASE_ADDR	0xc000
+MODULE_FIRMWARE(RCAR_GEN4_PCIE_FIRMWARE_NAME);
+
 struct rcar_gen4_pcie;
 struct rcar_gen4_pcie_drvdata {
+	void (*additional_common_init)(struct rcar_gen4_pcie *rcar);
 	int (*ltssm_control)(struct rcar_gen4_pcie *rcar, bool enable);
 	enum dw_pcie_device_mode mode;
 };
@@ -57,6 +80,7 @@ struct rcar_gen4_pcie_drvdata {
 struct rcar_gen4_pcie {
 	struct dw_pcie dw;
 	void __iomem *base;
+	void __iomem *phy_base;
 	struct platform_device *pdev;
 	const struct rcar_gen4_pcie_drvdata *drvdata;
 };
@@ -180,6 +204,9 @@ static int rcar_gen4_pcie_common_init(struct rcar_gen4_pcie *rcar)
 	if (ret)
 		goto err_unprepare;
 
+	if (rcar->drvdata->additional_common_init)
+		rcar->drvdata->additional_common_init(rcar);
+
 	return 0;
 
 err_unprepare:
@@ -221,6 +248,10 @@ static void rcar_gen4_pcie_unprepare(struct rcar_gen4_pcie *rcar)
 
 static int rcar_gen4_pcie_get_resources(struct rcar_gen4_pcie *rcar)
 {
+	rcar->phy_base = devm_platform_ioremap_resource_byname(rcar->pdev, "phy");
+	if (IS_ERR(rcar->phy_base))
+		return PTR_ERR(rcar->phy_base);
+
 	/* Renesas-specific registers */
 	rcar->base = devm_platform_ioremap_resource_byname(rcar->pdev, "app");
 
@@ -528,6 +559,167 @@ static int r8a779f0_pcie_ltssm_control(struct rcar_gen4_pcie *rcar, bool enable)
 	return 0;
 }
 
+static void rcar_gen4_pcie_additional_common_init(struct rcar_gen4_pcie *rcar)
+{
+	struct dw_pcie *dw = &rcar->dw;
+	u32 val;
+
+	val = dw_pcie_readl_dbi(dw, PCIE_PORT_LANE_SKEW);
+	val &= ~PORT_LANE_SKEW_INSERT_MASK;
+	if (dw->num_lanes < 4)
+		val |= BIT(6);
+	dw_pcie_writel_dbi(dw, PCIE_PORT_LANE_SKEW, val);
+
+	val = readl(rcar->base + PCIEPWRMNGCTRL);
+	val |= APP_CLK_REQ_N | APP_CLK_PM_EN;
+	writel(val, rcar->base + PCIEPWRMNGCTRL);
+}
+
+static void rcar_gen4_pcie_phy_reg_update_bits(struct rcar_gen4_pcie *rcar,
+					       u32 offset, u32 mask, u32 val)
+{
+	u32 tmp;
+
+	tmp = readl(rcar->phy_base + offset);
+	tmp &= ~mask;
+	tmp |= val;
+	writel(tmp, rcar->phy_base + offset);
+}
+
+/*
+ * SoC datasheet suggests checking port logic register bits during firmware
+ * write. If read returns non-zero value, then this function returns -EAGAIN
+ * indicating that the write needs to be done again. If read returns zero,
+ * then return 0 to indicate success.
+ */
+static int rcar_gen4_pcie_reg_test_bit(struct rcar_gen4_pcie *rcar,
+				       u32 offset, u32 mask)
+{
+	struct dw_pcie *dw = &rcar->dw;
+
+	if (dw_pcie_readl_dbi(dw, offset) & mask)
+		return -EAGAIN;
+
+	return 0;
+}
+
+static int rcar_gen4_pcie_download_phy_firmware(struct rcar_gen4_pcie *rcar)
+{
+	/* The check_addr values are magical numbers in the datasheet */
+	const u32 check_addr[] = { 0x00101018, 0x00101118, 0x00101021, 0x00101121};
+	struct dw_pcie *dw = &rcar->dw;
+	const struct firmware *fw;
+	unsigned int i, timeout;
+	u32 data;
+	int ret;
+
+	ret = request_firmware(&fw, RCAR_GEN4_PCIE_FIRMWARE_NAME, dw->dev);
+	if (ret) {
+		dev_err(dw->dev, "Failed to load firmware (%s): %d\n",
+			RCAR_GEN4_PCIE_FIRMWARE_NAME, ret);
+		return ret;
+	}
+
+	for (i = 0; i < (fw->size / 2); i++) {
+		data = fw->data[(i * 2) + 1] << 8 | fw->data[i * 2];
+		timeout = 100;
+		do {
+			dw_pcie_writel_dbi(dw, PRTLGC89, RCAR_GEN4_PCIE_FIRMWARE_BASE_ADDR + i);
+			dw_pcie_writel_dbi(dw, PRTLGC90, data);
+			if (!rcar_gen4_pcie_reg_test_bit(rcar, PRTLGC89, BIT(30)))
+				break;
+			if (!(--timeout)) {
+				ret = -ETIMEDOUT;
+				goto exit;
+			}
+			usleep_range(100, 200);
+		} while (1);
+	}
+
+	rcar_gen4_pcie_phy_reg_update_bits(rcar, 0x0f8, BIT(17), BIT(17));
+
+	for (i = 0; i < ARRAY_SIZE(check_addr); i++) {
+		timeout = 100;
+		do {
+			dw_pcie_writel_dbi(dw, PRTLGC89, check_addr[i]);
+			ret = rcar_gen4_pcie_reg_test_bit(rcar, PRTLGC89, BIT(30));
+			ret |= rcar_gen4_pcie_reg_test_bit(rcar, PRTLGC90, BIT(0));
+			if (!ret)
+				break;
+			if (!(--timeout)) {
+				ret = -ETIMEDOUT;
+				goto exit;
+			}
+			usleep_range(100, 200);
+		} while (1);
+	}
+
+exit:
+	release_firmware(fw);
+
+	return ret;
+}
+
+static int rcar_gen4_pcie_ltssm_control(struct rcar_gen4_pcie *rcar, bool enable)
+{
+	struct dw_pcie *dw = &rcar->dw;
+	u32 val;
+	int ret;
+
+	if (!enable) {
+		val = readl(rcar->base + PCIERSTCTRL1);
+		val &= ~APP_LTSSM_ENABLE;
+		writel(val, rcar->base + PCIERSTCTRL1);
+
+		return 0;
+	}
+
+	val = dw_pcie_readl_dbi(dw, PCIE_PORT_FORCE);
+	val |= PORT_FORCE_DO_DESKEW_FOR_SRIS;
+	dw_pcie_writel_dbi(dw, PCIE_PORT_FORCE, val);
+
+	val = readl(rcar->base + PCIEMSR0);
+	val |= APP_SRIS_MODE;
+	writel(val, rcar->base + PCIEMSR0);
+
+	/*
+	 * The R-Car Gen4 datasheet doesn't describe the PHY registers' name.
+	 * But, the initialization procedure describes these offsets. So,
+	 * this driver has magical offset numbers.
+	 */
+	rcar_gen4_pcie_phy_reg_update_bits(rcar, 0x700, BIT(28), 0);
+	rcar_gen4_pcie_phy_reg_update_bits(rcar, 0x700, BIT(20), 0);
+	rcar_gen4_pcie_phy_reg_update_bits(rcar, 0x700, BIT(12), 0);
+	rcar_gen4_pcie_phy_reg_update_bits(rcar, 0x700, BIT(4), 0);
+
+	rcar_gen4_pcie_phy_reg_update_bits(rcar, 0x148, GENMASK(23, 22), BIT(22));
+	rcar_gen4_pcie_phy_reg_update_bits(rcar, 0x148, GENMASK(18, 16), GENMASK(17, 16));
+	rcar_gen4_pcie_phy_reg_update_bits(rcar, 0x148, GENMASK(7, 6), BIT(6));
+	rcar_gen4_pcie_phy_reg_update_bits(rcar, 0x148, GENMASK(2, 0), GENMASK(11, 0));
+	rcar_gen4_pcie_phy_reg_update_bits(rcar, 0x1d4, GENMASK(16, 15), GENMASK(16, 15));
+	rcar_gen4_pcie_phy_reg_update_bits(rcar, 0x514, BIT(26), BIT(26));
+	rcar_gen4_pcie_phy_reg_update_bits(rcar, 0x0f8, BIT(16), 0);
+	rcar_gen4_pcie_phy_reg_update_bits(rcar, 0x0f8, BIT(19), BIT(19));
+
+	val = readl(rcar->base + PCIERSTCTRL1);
+	val &= ~APP_HOLD_PHY_RST;
+	writel(val, rcar->base + PCIERSTCTRL1);
+
+	ret = readl_poll_timeout(rcar->phy_base + 0x0f8, val, !(val & BIT(18)), 100, 10000);
+	if (ret < 0)
+		return ret;
+
+	ret = rcar_gen4_pcie_download_phy_firmware(rcar);
+	if (ret)
+		return ret;
+
+	val = readl(rcar->base + PCIERSTCTRL1);
+	val |= APP_LTSSM_ENABLE;
+	writel(val, rcar->base + PCIERSTCTRL1);
+
+	return 0;
+}
+
 static struct rcar_gen4_pcie_drvdata drvdata_r8a779f0_pcie = {
 	.ltssm_control = r8a779f0_pcie_ltssm_control,
 	.mode = DW_PCIE_RC_TYPE,
@@ -539,10 +731,14 @@ static struct rcar_gen4_pcie_drvdata drvdata_r8a779f0_pcie_ep = {
 };
 
 static struct rcar_gen4_pcie_drvdata drvdata_rcar_gen4_pcie = {
+	.additional_common_init = rcar_gen4_pcie_additional_common_init,
+	.ltssm_control = rcar_gen4_pcie_ltssm_control,
 	.mode = DW_PCIE_RC_TYPE,
 };
 
 static struct rcar_gen4_pcie_drvdata drvdata_rcar_gen4_pcie_ep = {
+	.additional_common_init = rcar_gen4_pcie_additional_common_init,
+	.ltssm_control = rcar_gen4_pcie_ltssm_control,
 	.mode = DW_PCIE_EP_TYPE,
 };