Message-ID: <20241126130004.1570091-5-christian.bruel@foss.st.com>
Date: Tue, 26 Nov 2024 14:00:03 +0100
From: Christian Bruel <christian.bruel@...s.st.com>
To: <lpieralisi@...nel.org>, <kw@...ux.com>,
        <manivannan.sadhasivam@...aro.org>, <robh@...nel.org>,
        <bhelgaas@...gle.com>, <krzk+dt@...nel.org>, <conor+dt@...nel.org>,
        <mcoquelin.stm32@...il.com>, <alexandre.torgue@...s.st.com>,
        <p.zabel@...gutronix.de>, <cassel@...nel.org>,
        <quic_schintav@...cinc.com>, <fabrice.gasnier@...s.st.com>
CC: <linux-pci@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        Christian Bruel <christian.bruel@...s.st.com>
Subject: [PATCH v1 4/5] PCI: stm32: Add PCIe endpoint support for STM32MP25

Add driver to configure the STM32MP25 SoC PCIe Gen2 controller based on the
DesignWare PCIe core in endpoint mode.

Uses the common reference clock provided by the host.

Signed-off-by: Christian Bruel <christian.bruel@...s.st.com>
---
 drivers/pci/controller/dwc/Kconfig         |  12 +
 drivers/pci/controller/dwc/Makefile        |   1 +
 drivers/pci/controller/dwc/pcie-stm32-ep.c | 445 +++++++++++++++++++++
 drivers/pci/controller/dwc/pcie-stm32.h    |   2 +
 4 files changed, 460 insertions(+)
 create mode 100644 drivers/pci/controller/dwc/pcie-stm32-ep.c

diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
index 0c18879b604c..f5601c81b56c 100644
--- a/drivers/pci/controller/dwc/Kconfig
+++ b/drivers/pci/controller/dwc/Kconfig
@@ -401,6 +401,18 @@ config PCIE_STM32
 	  This driver can also be built as a module. If so, the module
 	  will be called pcie-stm32.
 
+config PCIE_STM32_EP
+	tristate "STMicroelectronics STM32MP25 PCIe Controller (endpoint mode)"
+	depends on ARCH_STM32 || COMPILE_TEST
+	depends on PCI_ENDPOINT
+	select PCIE_DW_EP
+	help
+	  Enables endpoint support for DesignWare core based PCIe controller in found
+	  in STM32MP25 SoC.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called pcie-stm32-ep.
+
 config PCI_DRA7XX
 	tristate
 
diff --git a/drivers/pci/controller/dwc/Makefile b/drivers/pci/controller/dwc/Makefile
index 576d99cb3bc5..caebd98f6dd3 100644
--- a/drivers/pci/controller/dwc/Makefile
+++ b/drivers/pci/controller/dwc/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_PCIE_UNIPHIER_EP) += pcie-uniphier-ep.o
 obj-$(CONFIG_PCIE_VISCONTI_HOST) += pcie-visconti.o
 obj-$(CONFIG_PCIE_RCAR_GEN4) += pcie-rcar-gen4.o
 obj-$(CONFIG_PCIE_STM32) += pcie-stm32.o
+obj-$(CONFIG_PCIE_STM32_EP) += pcie-stm32-ep.o
 
 # The following drivers are for devices that use the generic ACPI
 # pci_root.c driver but don't support standard ECAM config access.
diff --git a/drivers/pci/controller/dwc/pcie-stm32-ep.c b/drivers/pci/controller/dwc/pcie-stm32-ep.c
new file mode 100644
index 000000000000..27f5725a7e76
--- /dev/null
+++ b/drivers/pci/controller/dwc/pcie-stm32-ep.c
@@ -0,0 +1,445 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * STMicroelectronics STM32MP25 PCIe endpoint driver.
+ *
+ * Copyright (C) 2024 STMicroelectronics
+ * Author: Christian Bruel <christian.bruel@...s.st.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of_platform.h>
+#include <linux/of_gpio.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+#include <linux/reset.h>
+#include "pcie-designware.h"
+#include "pcie-stm32.h"
+
+#define STM32MP25_PCIECR_EP 0
+#define STM32MP25_PCIECR_REQ_RETRY_EN	BIT(3)
+
+enum stm32_pcie_ep_link_status {
+	STM32_PCIE_EP_LINK_DISABLED,
+	STM32_PCIE_EP_LINK_ENABLED,
+};
+
+struct stm32_pcie {
+	struct dw_pcie *pci;
+	struct regmap *regmap;
+	struct reset_control *rst;
+	struct phy *phy;
+	struct clk *clk;
+	struct gpio_desc *perst_gpio;
+	enum stm32_pcie_ep_link_status link_status;
+	unsigned int perst_irq;
+};
+
+static void stm32_pcie_ep_init(struct dw_pcie_ep *ep)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
+	struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci);
+	enum pci_barno bar;
+
+	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++)
+		dw_pcie_ep_reset_bar(pci, bar);
+
+	/* Defer Completion Requests until link started */
+	regmap_update_bits(stm32_pcie->regmap, SYSCFG_PCIECR,
+			   STM32MP25_PCIECR_REQ_RETRY_EN,
+			   STM32MP25_PCIECR_REQ_RETRY_EN);
+}
+
+static int stm32_pcie_enable_link(struct dw_pcie *pci)
+{
+	struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci);
+	int ret;
+
+	regmap_update_bits(stm32_pcie->regmap, SYSCFG_PCIECR,
+			   STM32MP25_PCIECR_LTSSM_EN,
+			   STM32MP25_PCIECR_LTSSM_EN);
+
+	ret = dw_pcie_wait_for_link(pci);
+	if (ret)
+		return ret;
+
+	regmap_update_bits(stm32_pcie->regmap, SYSCFG_PCIECR,
+			   STM32MP25_PCIECR_REQ_RETRY_EN,
+			   0);
+
+	return 0;
+}
+
+static void stm32_pcie_disable_link(struct dw_pcie *pci)
+{
+	struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci);
+
+	regmap_update_bits(stm32_pcie->regmap, SYSCFG_PCIECR,
+			   STM32MP25_PCIECR_REQ_RETRY_EN,
+			   STM32MP25_PCIECR_REQ_RETRY_EN);
+
+	regmap_update_bits(stm32_pcie->regmap, SYSCFG_PCIECR, STM32MP25_PCIECR_LTSSM_EN, 0);
+}
+
+static int stm32_pcie_start_link(struct dw_pcie *pci)
+{
+	struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci);
+	int ret;
+
+	if (stm32_pcie->link_status == STM32_PCIE_EP_LINK_ENABLED) {
+		dev_dbg(pci->dev, "Link is already enabled\n");
+		return 0;
+	}
+
+	ret = stm32_pcie_enable_link(pci);
+	if (ret) {
+		dev_err(pci->dev, "PCIe cannot establish link: %d\n", ret);
+		return ret;
+	}
+
+	stm32_pcie->link_status = STM32_PCIE_EP_LINK_ENABLED;
+
+	enable_irq(stm32_pcie->perst_irq);
+
+	return 0;
+}
+
+static void stm32_pcie_stop_link(struct dw_pcie *pci)
+{
+	struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci);
+
+	if (stm32_pcie->link_status == STM32_PCIE_EP_LINK_DISABLED) {
+		dev_dbg(pci->dev, "Link is already disabled\n");
+		return;
+	}
+
+	disable_irq(stm32_pcie->perst_irq);
+
+	stm32_pcie_disable_link(pci);
+
+	stm32_pcie->link_status = STM32_PCIE_EP_LINK_DISABLED;
+}
+
+static int stm32_pcie_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
+				unsigned int type, u16 interrupt_num)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
+
+	switch (type) {
+	case PCI_IRQ_INTX:
+		return dw_pcie_ep_raise_intx_irq(ep, func_no);
+	case PCI_IRQ_MSI:
+		return dw_pcie_ep_raise_msi_irq(ep, func_no, interrupt_num);
+	default:
+		dev_err(pci->dev, "UNKNOWN IRQ type\n");
+		return -EINVAL;
+	}
+}
+
+static const struct pci_epc_features stm32_pcie_epc_features = {
+	.msi_capable = true,
+	.align = 1 << 16,
+};
+
+static const struct pci_epc_features*
+stm32_pcie_get_features(struct dw_pcie_ep *ep)
+{
+	return &stm32_pcie_epc_features;
+}
+
+static const struct dw_pcie_ep_ops stm32_pcie_ep_ops = {
+	.init = stm32_pcie_ep_init,
+	.raise_irq = stm32_pcie_raise_irq,
+	.get_features = stm32_pcie_get_features,
+};
+
+static const struct dw_pcie_ops dw_pcie_ops = {
+	.start_link = stm32_pcie_start_link,
+	.stop_link = stm32_pcie_stop_link,
+};
+
+static int stm32_pcie_enable_resources(struct stm32_pcie *stm32_pcie)
+{
+	int ret;
+
+	ret = phy_init(stm32_pcie->phy);
+	if (ret)
+		return ret;
+
+	ret = clk_prepare_enable(stm32_pcie->clk);
+	if (ret)
+		phy_exit(stm32_pcie->phy);
+
+	return ret;
+}
+
+static void stm32_pcie_disable_resources(struct stm32_pcie *stm32_pcie)
+{
+	clk_disable_unprepare(stm32_pcie->clk);
+
+	phy_exit(stm32_pcie->phy);
+}
+
+static void stm32_pcie_perst_assert(struct dw_pcie *pci)
+{
+	struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci);
+	struct device *dev = pci->dev;
+
+	dev_dbg(dev, "PERST asserted by host. Shutting down the PCIe link\n");
+
+	/*
+	 * Do not try to release resources if the PERST# is
+	 * asserted before the link is started.
+	 */
+	if (stm32_pcie->link_status == STM32_PCIE_EP_LINK_DISABLED) {
+		dev_dbg(pci->dev, "Link is already disabled\n");
+		return;
+	}
+
+	stm32_pcie_disable_link(pci);
+
+	stm32_pcie_disable_resources(stm32_pcie);
+
+	pm_runtime_put_sync(dev);
+
+	stm32_pcie->link_status = STM32_PCIE_EP_LINK_DISABLED;
+}
+
+static void stm32_pcie_perst_deassert(struct dw_pcie *pci)
+{
+	struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci);
+	struct device *dev = pci->dev;
+	struct dw_pcie_ep *ep = &pci->ep;
+	int ret;
+
+	if (stm32_pcie->link_status == STM32_PCIE_EP_LINK_ENABLED) {
+		dev_dbg(pci->dev, "Link is already enabled\n");
+		return;
+	}
+
+	dev_dbg(dev, "PERST de-asserted by host. Starting link training\n");
+
+	ret = pm_runtime_resume_and_get(dev);
+	if (ret < 0) {
+		dev_err(dev, "pm runtime resume failed: %d\n", ret);
+		return;
+	}
+
+	ret = stm32_pcie_enable_resources(stm32_pcie);
+	if (ret) {
+		dev_err(dev, "Failed to enable resources: %d\n", ret);
+		goto err_clk;
+	}
+
+	ret = dw_pcie_ep_init_registers(ep);
+	if (ret) {
+		dev_err(dev, "Failed to complete initialization: %d\n", ret);
+		goto err_init_regs;
+	}
+
+	pci_epc_init_notify(ep->epc);
+
+	ret = stm32_pcie_enable_link(pci);
+	if (ret) {
+		dev_err(dev, "PCIe Cannot establish link: %d\n", ret);
+		goto err_link;
+	}
+
+	stm32_pcie->link_status = STM32_PCIE_EP_LINK_ENABLED;
+
+	return;
+
+err_link:
+	pci_epc_deinit_notify(ep->epc);
+
+err_init_regs:
+	stm32_pcie_disable_resources(stm32_pcie);
+
+err_clk:
+	pm_runtime_put_sync(dev);
+}
+
+static irqreturn_t stm32_pcie_ep_perst_irq_thread(int irq, void *data)
+{
+	struct stm32_pcie *stm32_pcie = data;
+	struct dw_pcie *pci = stm32_pcie->pci;
+	u32 perst;
+
+	perst = gpiod_get_value(stm32_pcie->perst_gpio);
+	if (perst)
+		stm32_pcie_perst_assert(pci);
+	else
+		stm32_pcie_perst_deassert(pci);
+
+	return IRQ_HANDLED;
+}
+
+static int stm32_add_pcie_ep(struct stm32_pcie *stm32_pcie,
+			     struct platform_device *pdev)
+{
+	struct dw_pcie *pci = stm32_pcie->pci;
+	struct dw_pcie_ep *ep = &pci->ep;
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	ret = regmap_update_bits(stm32_pcie->regmap, SYSCFG_PCIECR,
+				 STM32MP25_PCIECR_TYPE_MASK,
+				 STM32MP25_PCIECR_EP);
+	if (ret)
+		return ret;
+
+	ret = pm_runtime_resume_and_get(dev);
+	if (ret < 0) {
+		dev_err(dev, "pm runtime resume failed: %d\n", ret);
+		return ret;
+	}
+
+	reset_control_assert(stm32_pcie->rst);
+	reset_control_deassert(stm32_pcie->rst);
+
+	ep->ops = &stm32_pcie_ep_ops;
+
+	ret = dw_pcie_ep_init(ep);
+	if (ret) {
+		dev_err(dev, "failed to initialize ep: %d\n", ret);
+		goto err_init;
+	}
+
+	ret = stm32_pcie_enable_resources(stm32_pcie);
+	if (ret) {
+		dev_err(dev, "failed to enable resources: %d\n", ret);
+		goto err_clk;
+	}
+
+	ret = dw_pcie_ep_init_registers(ep);
+	if (ret) {
+		dev_err(dev, "Failed to initialize DWC endpoint registers\n");
+		goto err_init_regs;
+	}
+
+	pci_epc_init_notify(ep->epc);
+
+	return 0;
+
+err_init_regs:
+	stm32_pcie_disable_resources(stm32_pcie);
+
+err_clk:
+	dw_pcie_ep_deinit(ep);
+
+err_init:
+	pm_runtime_put_sync(dev);
+	return ret;
+}
+
+static int stm32_pcie_probe(struct platform_device *pdev)
+{
+	struct stm32_pcie *stm32_pcie;
+	struct dw_pcie *dw;
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	stm32_pcie = devm_kzalloc(dev, sizeof(*stm32_pcie), GFP_KERNEL);
+	if (!stm32_pcie)
+		return -ENOMEM;
+
+	dw = devm_kzalloc(dev, sizeof(*dw), GFP_KERNEL);
+	if (!dw)
+		return -ENOMEM;
+
+	stm32_pcie->pci = dw;
+
+	dw->dev = dev;
+	dw->ops = &dw_pcie_ops;
+
+	stm32_pcie->regmap = syscon_regmap_lookup_by_compatible("st,stm32mp25-syscfg");
+	if (IS_ERR(stm32_pcie->regmap))
+		return dev_err_probe(dev, PTR_ERR(stm32_pcie->regmap),
+				     "No syscfg specified\n");
+
+	stm32_pcie->phy = devm_phy_get(dev, "pcie-phy");
+	if (IS_ERR(stm32_pcie->phy))
+		return dev_err_probe(dev, PTR_ERR(stm32_pcie->phy),
+				     "failed to get pcie-phy\n");
+
+	stm32_pcie->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(stm32_pcie->clk))
+		return dev_err_probe(dev, PTR_ERR(stm32_pcie->clk),
+				     "Failed to get PCIe clock source\n");
+
+	stm32_pcie->rst = devm_reset_control_get_exclusive(dev, NULL);
+	if (IS_ERR(stm32_pcie->rst))
+		return dev_err_probe(dev, PTR_ERR(stm32_pcie->rst),
+				     "Failed to get PCIe reset\n");
+
+	stm32_pcie->perst_gpio = devm_gpiod_get(dev, "reset", GPIOD_IN);
+	if (IS_ERR(stm32_pcie->perst_gpio))
+		return dev_err_probe(dev, PTR_ERR(stm32_pcie->perst_gpio),
+				     "Failed to get reset GPIO\n");
+
+	ret = phy_set_mode(stm32_pcie->phy, PHY_MODE_PCIE);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, stm32_pcie);
+
+	ret = devm_pm_runtime_enable(dev);
+	if (ret < 0) {
+		dev_err(dev, "Failed to enable pm runtime %d\n", ret);
+		return ret;
+	}
+
+	stm32_pcie->perst_irq = gpiod_to_irq(stm32_pcie->perst_gpio);
+
+	/* Will be enabled in start_link when device is initialized. */
+	irq_set_status_flags(stm32_pcie->perst_irq, IRQ_NOAUTOEN);
+
+	ret = devm_request_threaded_irq(dev, stm32_pcie->perst_irq, NULL,
+					stm32_pcie_ep_perst_irq_thread,
+					IRQF_TRIGGER_RISING |
+					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+					"perst_irq", stm32_pcie);
+	if (ret) {
+		dev_err(dev, "Failed to request PERST IRQ: %d\n", ret);
+		return ret;
+	}
+
+	return stm32_add_pcie_ep(stm32_pcie, pdev);
+}
+
+static void stm32_pcie_remove(struct platform_device *pdev)
+{
+	struct stm32_pcie *stm32_pcie = platform_get_drvdata(pdev);
+	struct dw_pcie_ep *ep = &stm32_pcie->pci->ep;
+
+	disable_irq(stm32_pcie->perst_irq);
+
+	dw_pcie_ep_deinit(ep);
+
+	stm32_pcie_disable_resources(stm32_pcie);
+
+	pm_runtime_put_sync(&pdev->dev);
+}
+
+static const struct of_device_id stm32_pcie_ep_of_match[] = {
+	{ .compatible = "st,stm32mp25-pcie-ep" },
+	{},
+};
+
+static struct platform_driver stm32_pcie_ep_driver = {
+	.probe = stm32_pcie_probe,
+	.remove = stm32_pcie_remove,
+	.driver = {
+		.name = "stm32-ep-pcie",
+		.of_match_table = stm32_pcie_ep_of_match,
+	},
+};
+
+module_platform_driver(stm32_pcie_ep_driver);
+
+MODULE_AUTHOR("Christian Bruel <christian.bruel@...s.st.com>");
+MODULE_DESCRIPTION("STM32MP25 PCIe Endpoint Controller driver");
+MODULE_LICENSE("GPL");
+MODULE_DEVICE_TABLE(of, stm32_pcie_ep_of_match);
diff --git a/drivers/pci/controller/dwc/pcie-stm32.h b/drivers/pci/controller/dwc/pcie-stm32.h
index 3efd00937d3d..ac0955adf150 100644
--- a/drivers/pci/controller/dwc/pcie-stm32.h
+++ b/drivers/pci/controller/dwc/pcie-stm32.h
@@ -9,7 +9,9 @@
 #define to_stm32_pcie(x)	dev_get_drvdata((x)->dev)
 
 #define STM32MP25_PCIECR_TYPE_MASK	GENMASK(11, 8)
+#define STM32MP25_PCIECR_EP		0
 #define STM32MP25_PCIECR_LTSSM_EN	BIT(2)
+#define STM32MP25_PCIECR_REQ_RETRY_EN	BIT(3)
 #define STM32MP25_PCIECR_RC		BIT(10)
 
 #define SYSCFG_PCIECR			0x6000
-- 
2.34.1

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