[PATCH v5 6/6] PCI: dwc: rcar-gen4: Add support for R-Car X5H PCIe4

[Marek Vasut <marek.vasut+renesas@mailbox.org>]

Add support for R8A78000 (R-Car X5H) PCIe4.

This driver previously supported R-Car Gen4 S4/V4H/V4M. PCIe features
of R-Car X5H PCIe4 are almost all the same.

The controller initialization sequence is slightly different and is
factored out into controller specific callbacks, in a manner similar
to previous R-Car Gen4 handling.

The controller does have a PHY attached to it, but the PHY is operated
by a separate PHY driver, the PHY driver instance binding is handled
in rcar_gen4_pcie_get_resources() and controlled in the aforementioned
controller specific callbacks.

The controller driver is deliberately using "renesas,rcar-gen5-pcie4"
DT compatible string to discern R-Car X5H PCIe4 controller supported
by this driver, from R-Car X5H PCIe6 controller which will most likely
use a separate driver.

The R-Car X5H PCIe4 controller embeds HDMA instead of EDMA embedded
in the R-Car Gen4 PCIe controller, "dw-edma" driver supports both
DMA variants.

Endpoint mode is currently not implemented for R-Car Gen5 PCIe4.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
---
Cc: "Krzysztof Wilczyński" <kwilczynski@kernel.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Conor Dooley <conor+dt@kernel.org>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Krzysztof Kozlowski <krzk+dt@kernel.org>
Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>
Cc: Manivannan Sadhasivam <mani@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-pci@vger.kernel.org
Cc: linux-renesas-soc@vger.kernel.org
---
V2: No change
V3: - Disable clock in case of PHY init failure in rcar_gen5_pcie_init()
    - Add .deinit callback and tear down Gen5 PHY in it
    - Use 16bit accessors on LNKCTL register
V4: Rebase on next-20260904
V5: Use read_poll_timeout() with 500ms timeout for the controller link up detection
---
 drivers/pci/controller/dwc/pcie-rcar-gen4.c | 120 +++++++++++++++++++-
 1 file changed, 118 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-rcar-gen4.c b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
index cf1f5de451820..0b7ae4a693085 100644
--- a/drivers/pci/controller/dwc/pcie-rcar-gen4.c
+++ b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
@@ -19,6 +19,7 @@
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
 #include <linux/pci.h>
+#include <linux/phy/phy.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/reset.h>
@@ -36,6 +37,7 @@
 
 /* MSI Capability */
 #define MSICAP0			0x0050
+#define MSICAP0_MMESCAP_MASK	GENMASK(19, 17)
 #define MSICAP0_MSIE		BIT(16)
 
 /* PCIe Interrupt Status 0 */
@@ -74,6 +76,11 @@
 #define PCIEPWRMNGCTRL		0x0070
 #define APP_CLK_REQ_N		BIT(11)
 #define APP_CLK_PM_EN		BIT(10)
+#define APP_READY_ENTR_L23	BIT(6)
+#define APP_REQ_ENTR_L1		BIT(5)
+
+/* PCI Express capability */
+#define EXPCAP(x)		(0x0070 + (x))
 
 #define RCAR_NUM_SPEED_CHANGE_RETRIES	10
 #define RCAR_MAX_LINK_SPEED		4
@@ -98,6 +105,7 @@ struct rcar_gen4_pcie {
 	struct dw_pcie dw;
 	void __iomem *base;
 	void __iomem *phy_base;
+	struct phy *phy;
 	struct platform_device *pdev;
 	struct reset_control *perst;
 	const struct rcar_gen4_pcie_drvdata *drvdata;
@@ -170,6 +178,27 @@ static int rcar_gen4_pcie_speed_control(struct rcar_gen4_pcie *rcar)
 	return 0;
 }
 
+static int rcar_gen5_pcie_speed_control(struct rcar_gen4_pcie *rcar)
+{
+	struct dw_pcie *dw = &rcar->dw;
+	u32 lnkcap = dw_pcie_readl_dbi(dw, EXPCAP(PCI_EXP_LNKCAP));
+	u32 lnksta = dw_pcie_readw_dbi(dw, EXPCAP(PCI_EXP_LNKSTA));
+	u32 val;
+
+	if ((lnksta & PCI_EXP_LNKSTA_CLS) == (lnkcap & PCI_EXP_LNKCAP_SLS))
+		return 0;
+
+	/* Retrain link */
+	val = dw_pcie_readw_dbi(dw, EXPCAP(PCI_EXP_LNKCTL));
+	val |= PCI_EXP_LNKCTL_RL;
+	dw_pcie_writew_dbi(dw, EXPCAP(PCI_EXP_LNKCTL), val);
+
+	/* Wait for link retrain, 500ms must be enough for all link rates. */
+	return read_poll_timeout(dw_pcie_readw_dbi, lnksta, !(lnksta & PCI_EXP_LNKSTA_LT),
+				 1000, 5 * PCIE_RESET_CONFIG_WAIT_MS * USEC_PER_MSEC,
+				 false, dw, EXPCAP(PCI_EXP_LNKSTA));
+}
+
 /*
  * Enable LTSSM of this controller and manually initiate the speed change.
  * Always return 0.
@@ -285,6 +314,49 @@ static int rcar_gen4_v4h_v4m_pcie_init(struct rcar_gen4_pcie *rcar)
 	return 0;
 }
 
+static int rcar_gen5_pcie_init(struct rcar_gen4_pcie *rcar)
+{
+	struct dw_pcie *dw = &rcar->dw;
+	int ret;
+	u32 val;
+
+	/* R-Car Gen4 and Gen5 common initialization. */
+	ret = rcar_gen4_pcie_common_init(rcar);
+	if (ret)
+		return ret;
+
+	/* R-Car Gen5 specific additional initialization. */
+	ret = phy_init(rcar->phy);
+	if (ret)
+		goto err_unprepare;
+
+	dw_pcie_dbi_ro_wr_en(dw);
+
+	val = dw_pcie_readl_dbi(dw, PCIE_PORT_LANE_SKEW);
+	val &= ~PORT_LANE_SKEW_INSERT_MASK;
+	if (dw->num_lanes < 8)
+		val |= BIT(6);
+	dw_pcie_writel_dbi(dw, PCIE_PORT_LANE_SKEW, val);
+
+	val = dw_pcie_readl_dbi(dw, MSICAP0);
+	FIELD_MODIFY(MSICAP0_MMESCAP_MASK, &val, 4);
+	dw_pcie_writel_dbi(dw, MSICAP0, val);
+
+	dw_pcie_dbi_ro_wr_dis(dw);
+
+	val = readl(rcar->base + PCIEPWRMNGCTRL);
+	val |= APP_CLK_REQ_N | APP_CLK_PM_EN |
+	       APP_READY_ENTR_L23 | APP_REQ_ENTR_L1;
+	writel(val, rcar->base + PCIEPWRMNGCTRL);
+
+	return 0;
+
+err_unprepare:
+	clk_bulk_disable_unprepare(DW_PCIE_NUM_CORE_CLKS, dw->core_clks);
+
+	return ret;
+}
+
 static void rcar_gen4_pcie_common_deinit(struct rcar_gen4_pcie *rcar)
 {
 	struct dw_pcie *dw = &rcar->dw;
@@ -293,6 +365,12 @@ static void rcar_gen4_pcie_common_deinit(struct rcar_gen4_pcie *rcar)
 	clk_bulk_disable_unprepare(DW_PCIE_NUM_CORE_CLKS, dw->core_clks);
 }
 
+static void rcar_gen5_pcie_deinit(struct rcar_gen4_pcie *rcar)
+{
+	phy_exit(rcar->phy);
+	rcar_gen4_pcie_common_deinit(rcar);
+}
+
 static int rcar_gen4_pcie_prepare(struct rcar_gen4_pcie *rcar)
 {
 	struct device *dev = rcar->dw.dev;
@@ -322,8 +400,12 @@ static int rcar_gen4_pcie_get_resources(struct rcar_gen4_pcie *rcar)
 	struct device_node *root_port;
 
 	rcar->phy_base = devm_platform_ioremap_resource_byname(rcar->pdev, "phy");
-	if (IS_ERR(rcar->phy_base))
-		return PTR_ERR(rcar->phy_base);
+	if (IS_ERR(rcar->phy_base)) {
+		rcar->phy_base = NULL;
+		rcar->phy = devm_phy_get(dev, NULL);
+		if (IS_ERR(rcar->phy))
+			return PTR_ERR(rcar->phy);
+	}
 
 	root_port = of_get_next_available_child(dev->of_node, NULL);
 	if (root_port) {
@@ -804,6 +886,28 @@ static int r8a779f0_pcie_ltssm_control(struct rcar_gen4_pcie *rcar, bool enable)
 	return 0;
 }
 
+static int rcar_gen5_pcie_ltssm_control(struct rcar_gen4_pcie *rcar, bool enable)
+{
+	u32 val;
+
+	val = readl(rcar->base + PCIERSTCTRL1);
+	if (enable) {
+		val |= APP_LTSSM_ENABLE;
+		val &= ~APP_HOLD_PHY_RST;
+	} else {
+		val &= ~APP_LTSSM_ENABLE;
+		val |= APP_HOLD_PHY_RST;
+	}
+	writel(val, rcar->base + PCIERSTCTRL1);
+
+	if (enable)
+		phy_power_on(rcar->phy);
+	else
+		phy_power_off(rcar->phy);
+
+	return 0;
+}
+
 static void rcar_gen4_pcie_phy_reg_update_bits(struct rcar_gen4_pcie *rcar,
 					       u32 offset, u32 mask, u32 val)
 {
@@ -986,6 +1090,14 @@ static struct rcar_gen4_pcie_drvdata drvdata_rcar_gen4_pcie_ep = {
 	.mode = DW_PCIE_EP_TYPE,
 };
 
+static struct rcar_gen4_pcie_drvdata drvdata_rcar_gen5_pcie = {
+	.init = rcar_gen5_pcie_init,
+	.deinit = rcar_gen5_pcie_deinit,
+	.ltssm_control = rcar_gen5_pcie_ltssm_control,
+	.speed_control = rcar_gen5_pcie_speed_control,
+	.mode = DW_PCIE_RC_TYPE,
+};
+
 static const struct of_device_id rcar_gen4_pcie_of_match[] = {
 	{
 		.compatible = "renesas,r8a779f0-pcie",
@@ -1003,6 +1115,10 @@ static const struct of_device_id rcar_gen4_pcie_of_match[] = {
 		.compatible = "renesas,rcar-gen4-pcie-ep",
 		.data = &drvdata_rcar_gen4_pcie_ep,
 	},
+	{
+		.compatible = "renesas,rcar-gen5-pcie4",
+		.data = &drvdata_rcar_gen5_pcie,
+	},
 	{},
 };
 MODULE_DEVICE_TABLE(of, rcar_gen4_pcie_of_match);
-- 
2.53.0