Message-ID: <20241112161925.999196-3-christian.bruel@foss.st.com>
Date: Tue, 12 Nov 2024 17:19:22 +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 2/5] PCI: stm32: Add PCIe host support for STM32MP25

Add driver for the STM32MP25 SoC PCIe Gen2 controller based on the
DesignWare PCIe core.
Supports MSI via GICv2m, Single Virtual Channel, Single Function

Signed-off-by: Christian Bruel <christian.bruel@...s.st.com>
---
 drivers/pci/controller/dwc/Kconfig      |  11 +
 drivers/pci/controller/dwc/Makefile     |   1 +
 drivers/pci/controller/dwc/pcie-stm32.c | 493 ++++++++++++++++++++++++
 drivers/pci/controller/dwc/pcie-stm32.h |  24 ++
 4 files changed, 529 insertions(+)
 create mode 100644 drivers/pci/controller/dwc/pcie-stm32.c
 create mode 100644 drivers/pci/controller/dwc/pcie-stm32.h

diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
index b6d6778b0698..50a014c2dfd0 100644
--- a/drivers/pci/controller/dwc/Kconfig
+++ b/drivers/pci/controller/dwc/Kconfig
@@ -459,4 +459,15 @@ config PCIE_VISCONTI_HOST
 	  Say Y here if you want PCIe controller support on Toshiba Visconti SoC.
 	  This driver supports TMPV7708 SoC.
 
+config PCIE_STM32
+	tristate "STMicroelectronics STM32MP25 PCIe Controller (host mode)"
+	depends on ARCH_STM32 || COMPILE_TEST
+	depends on PCI_MSI
+	select PCIE_DW_HOST
+	help
+	  Enables support for the DesignWare core based PCIe host controller
+	  found in STM32MP25 SoC.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called pcie-stm32.
 endmenu
diff --git a/drivers/pci/controller/dwc/Makefile b/drivers/pci/controller/dwc/Makefile
index a8308d9ea986..576d99cb3bc5 100644
--- a/drivers/pci/controller/dwc/Makefile
+++ b/drivers/pci/controller/dwc/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_PCIE_UNIPHIER) += pcie-uniphier.o
 obj-$(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
 
 # 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.c b/drivers/pci/controller/dwc/pcie-stm32.c
new file mode 100644
index 000000000000..c27ab580a3bf
--- /dev/null
+++ b/drivers/pci/controller/dwc/pcie-stm32.c
@@ -0,0 +1,493 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * STMicroelectronics STM32MP25 PCIe root complex 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/phy/phy.h>
+#include <linux/pinctrl/devinfo.h>
+#include <linux/pm_runtime.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/reset.h>
+#include "pcie-designware.h"
+#include "pcie-stm32.h"
+
+struct stm32_pcie {
+	struct dw_pcie *pci;
+	struct regmap *regmap;
+	struct reset_control *rst;
+	struct phy *phy;
+	struct clk *clk;
+	struct gpio_desc *reset_gpio;
+	struct gpio_desc *wake_gpio;
+	unsigned int wake_irq;
+	u32 max_payload;
+	bool limit_downstream_mrrs;
+	bool link_is_up;
+};
+
+static const struct of_device_id stm32_pcie_of_match[] = {
+	{ .compatible = "st,stm32mp25-pcie-rc" },
+	{},
+};
+
+static int stm32_pcie_set_max_payload(struct dw_pcie *pci, int mps)
+{
+	int ret;
+	struct device *dev = pci->dev;
+	struct pci_dev *pdev = to_pci_dev(dev);
+
+	if (mps != 128 && mps != 256) {
+		dev_err(dev, "Unexpected payload size %d\n", mps);
+		return -EINVAL;
+	}
+
+	ret = pcie_set_mps(pdev, mps);
+	if (ret)
+		dev_err(dev, "failed to set mps %d, error %d\n", mps, ret);
+
+	return ret;
+}
+
+static int stm32_pcie_host_init(struct dw_pcie_rp *pp)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci);
+
+	if (stm32_pcie->max_payload)
+		return stm32_pcie_set_max_payload(pci, stm32_pcie->max_payload);
+
+	return 0;
+}
+
+static int stm32_pcie_start_link(struct dw_pcie *pci)
+{
+	struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci);
+	u32 ret;
+
+	if (stm32_pcie->reset_gpio) {
+		/* Make sure PERST# is asserted. */
+		gpiod_set_value(stm32_pcie->reset_gpio, 1);
+
+		/* Deassert PERST# after 100us */
+		usleep_range(100, 200);
+		gpiod_set_value(stm32_pcie->reset_gpio, 0);
+	}
+
+	ret = regmap_update_bits(stm32_pcie->regmap, SYSCFG_PCIECR,
+				 STM32MP25_PCIECR_LTSSM_EN,
+				 STM32MP25_PCIECR_LTSSM_EN);
+
+	/*
+	 * PCIe specification states that you should not issue any config
+	 * requests until 100ms after asserting reset, so we enforce that here
+	 */
+	if (stm32_pcie->reset_gpio)
+		msleep(100);
+
+	return ret;
+}
+
+static void stm32_pcie_stop_link(struct dw_pcie *pci)
+{
+	struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci);
+
+	regmap_update_bits(stm32_pcie->regmap, SYSCFG_PCIECR, STM32MP25_PCIECR_LTSSM_EN, 0);
+
+	/* Assert PERST# */
+	if (stm32_pcie->reset_gpio)
+		gpiod_set_value(stm32_pcie->reset_gpio, 1);
+}
+
+static int stm32_pcie_suspend(struct device *dev)
+{
+	struct stm32_pcie *stm32_pcie = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(dev) || device_wakeup_path(dev))
+		enable_irq_wake(stm32_pcie->wake_irq);
+
+	return 0;
+}
+
+static int stm32_pcie_resume(struct device *dev)
+{
+	struct stm32_pcie *stm32_pcie = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(dev) || device_wakeup_path(dev))
+		disable_irq_wake(stm32_pcie->wake_irq);
+
+	return 0;
+}
+
+static int stm32_pcie_suspend_noirq(struct device *dev)
+{
+	struct stm32_pcie *stm32_pcie = dev_get_drvdata(dev);
+
+	stm32_pcie->link_is_up = dw_pcie_link_up(stm32_pcie->pci);
+
+	stm32_pcie_stop_link(stm32_pcie->pci);
+	clk_disable_unprepare(stm32_pcie->clk);
+
+	if (!device_may_wakeup(dev) && !device_wakeup_path(dev))
+		phy_exit(stm32_pcie->phy);
+
+	return pinctrl_pm_select_sleep_state(dev);
+}
+
+static int stm32_pcie_resume_noirq(struct device *dev)
+{
+	struct stm32_pcie *stm32_pcie = dev_get_drvdata(dev);
+	struct dw_pcie *pci = stm32_pcie->pci;
+	struct dw_pcie_rp *pp = &pci->pp;
+	int ret;
+
+	/* init_state was set in pinctrl_bind_pins() before probe */
+	if (!IS_ERR(dev->pins->init_state))
+		ret = pinctrl_select_state(dev->pins->p, dev->pins->init_state);
+	else
+		ret = pinctrl_pm_select_default_state(dev);
+
+	if (ret) {
+		dev_err(dev, "Failed to activate pinctrl pm state: %d\n", ret);
+		return ret;
+	}
+
+	if (!device_may_wakeup(dev) && !device_wakeup_path(dev)) {
+		ret = phy_init(stm32_pcie->phy);
+		if (ret) {
+			pinctrl_pm_select_default_state(dev);
+			return ret;
+		}
+	}
+
+	ret = clk_prepare_enable(stm32_pcie->clk);
+	if (ret)
+		goto clk_err;
+
+	ret = stm32_pcie_host_init(pp);
+	if (ret)
+		goto host_err;
+
+	ret = dw_pcie_setup_rc(pp);
+	if (ret)
+		goto pcie_err;
+
+	if (stm32_pcie->link_is_up) {
+		ret = stm32_pcie_start_link(stm32_pcie->pci);
+		if (ret)
+			goto pcie_err;
+
+		/* Ignore errors, the link may come up later */
+		dw_pcie_wait_for_link(stm32_pcie->pci);
+	}
+
+	pinctrl_pm_select_default_state(dev);
+
+	return 0;
+
+pcie_err:
+	dw_pcie_host_deinit(pp);
+host_err:
+	clk_disable_unprepare(stm32_pcie->clk);
+clk_err:
+	phy_exit(stm32_pcie->phy);
+	pinctrl_pm_select_default_state(dev);
+
+	return ret;
+}
+
+static const struct dev_pm_ops stm32_pcie_pm_ops = {
+	NOIRQ_SYSTEM_SLEEP_PM_OPS(stm32_pcie_suspend_noirq,
+				  stm32_pcie_resume_noirq)
+	SYSTEM_SLEEP_PM_OPS(stm32_pcie_suspend, stm32_pcie_resume)
+};
+
+static const struct dw_pcie_host_ops stm32_pcie_host_ops = {
+	.init = stm32_pcie_host_init
+};
+
+static const struct dw_pcie_ops dw_pcie_ops = {
+	.start_link = stm32_pcie_start_link,
+	.stop_link = stm32_pcie_stop_link
+};
+
+static irqreturn_t stm32_pcie_wake_irq_handler(int irq, void *priv)
+{
+	struct stm32_pcie *stm32_pcie = priv;
+	struct device *dev = stm32_pcie->pci->dev;
+
+	dev_dbg(dev, "PCIE host wakeup by EP");
+
+	/* Notify PM core we are wakeup source */
+	pm_wakeup_event(dev, 0);
+	pm_system_wakeup();
+
+	return IRQ_HANDLED;
+}
+
+static int stm32_add_pcie_port(struct stm32_pcie *stm32_pcie,
+			       struct platform_device *pdev)
+{
+	struct dw_pcie *pci = stm32_pcie->pci;
+	struct device *dev = pci->dev;
+	struct dw_pcie_rp *pp = &pci->pp;
+	int ret;
+
+	ret = phy_set_mode(stm32_pcie->phy, PHY_MODE_PCIE);
+	if (ret)
+		return ret;
+
+	ret = phy_init(stm32_pcie->phy);
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(stm32_pcie->regmap, SYSCFG_PCIECR,
+				 STM32MP25_PCIECR_TYPE_MASK, STM32MP25_PCIECR_RC);
+	if (ret)
+		goto phy_disable;
+
+	reset_control_assert(stm32_pcie->rst);
+	reset_control_deassert(stm32_pcie->rst);
+
+	ret = clk_prepare_enable(stm32_pcie->clk);
+	if (ret) {
+		dev_err(dev, "Core clock enable failed %d\n", ret);
+		goto phy_disable;
+	}
+
+	pp->ops = &stm32_pcie_host_ops;
+	ret = dw_pcie_host_init(pp);
+	if (ret) {
+		dev_err(dev, "failed to initialize host: %d\n", ret);
+		clk_disable_unprepare(stm32_pcie->clk);
+		goto phy_disable;
+	}
+
+	return 0;
+
+phy_disable:
+	phy_exit(stm32_pcie->phy);
+
+	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;
+	struct device_node *np = pdev->dev.of_node;
+	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, "core");
+	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, "core");
+	if (IS_ERR(stm32_pcie->rst))
+		return dev_err_probe(dev, PTR_ERR(stm32_pcie->rst),
+				     "Failed to get PCIe reset\n");
+
+	/* Optionally limit payload */
+	ret = of_property_read_u32(np, "st,max-payload-size", &stm32_pcie->max_payload);
+	if (ret && ret != -EINVAL)
+		return dev_err_probe(dev, ret, "Error reading max-payload value\n");
+
+	if (of_property_read_bool(np, "st,limit-mrrs"))
+		stm32_pcie->limit_downstream_mrrs = true;
+
+	stm32_pcie->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(stm32_pcie->reset_gpio))
+		return dev_err_probe(dev, PTR_ERR(stm32_pcie->reset_gpio),
+				     "Failed to get reset GPIO\n");
+
+	platform_set_drvdata(pdev, stm32_pcie);
+
+	if (device_property_read_bool(dev, "wakeup-source")) {
+		stm32_pcie->wake_gpio = devm_gpiod_get_optional(dev, "wake", GPIOD_IN);
+		if (IS_ERR(stm32_pcie->wake_gpio))
+			return dev_err_probe(dev, PTR_ERR(stm32_pcie->wake_gpio),
+					     "Failed to get wake GPIO\n");
+	}
+
+	if (stm32_pcie->wake_gpio) {
+		stm32_pcie->wake_irq = gpiod_to_irq(stm32_pcie->wake_gpio);
+
+		ret = devm_request_threaded_irq(&pdev->dev, stm32_pcie->wake_irq, NULL,
+						stm32_pcie_wake_irq_handler,
+						IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+						"wake_irq", stm32_pcie);
+
+		if (ret)
+			return dev_err_probe(dev, ret, "Failed to request WAKE IRQ: %d\n", ret);
+	}
+
+	ret = devm_pm_runtime_enable(dev);
+	if (ret < 0) {
+		dev_err(dev, "Failed to enable pm runtime %d\n", 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;
+	}
+
+	ret = stm32_add_pcie_port(stm32_pcie, pdev);
+	if (ret)  {
+		pm_runtime_put_sync(&pdev->dev);
+		return ret;
+	}
+
+	if (stm32_pcie->wake_gpio)
+		device_set_wakeup_capable(dev, true);
+
+	return 0;
+}
+
+static void stm32_pcie_remove(struct platform_device *pdev)
+{
+	struct stm32_pcie *stm32_pcie = platform_get_drvdata(pdev);
+	struct dw_pcie_rp *pp = &stm32_pcie->pci->pp;
+
+	if (stm32_pcie->wake_gpio)
+		device_init_wakeup(&pdev->dev, false);
+
+	dw_pcie_host_deinit(pp);
+	clk_disable_unprepare(stm32_pcie->clk);
+
+	phy_exit(stm32_pcie->phy);
+
+	pm_runtime_put_sync(&pdev->dev);
+}
+
+static struct platform_driver stm32_pcie_driver = {
+	.probe = stm32_pcie_probe,
+	.remove_new = stm32_pcie_remove,
+	.driver = {
+		.name = "stm32-pcie",
+		.of_match_table = stm32_pcie_of_match,
+		.pm		= &stm32_pcie_pm_ops,
+	},
+};
+
+static bool is_stm32_pcie_driver(struct device *dev)
+{
+	/* PCI bridge */
+	dev = get_device(dev);
+
+	/* Platform driver */
+	dev = get_device(dev->parent);
+
+	return (dev->driver == &stm32_pcie_driver.driver);
+}
+
+static bool apply_mrrs_quirk(struct pci_dev *root_port)
+{
+	struct dw_pcie_rp *pp;
+	struct dw_pcie *dw_pci;
+	struct stm32_pcie *stm32_pcie;
+
+	if (WARN_ON(!root_port) || !is_stm32_pcie_driver(root_port->dev.parent))
+		return false;
+
+	pp = root_port->bus->sysdata;
+	dw_pci = to_dw_pcie_from_pp(pp);
+	stm32_pcie = to_stm32_pcie(dw_pci);
+
+	if (!stm32_pcie->limit_downstream_mrrs)
+		return false;
+
+	return true;
+}
+
+static void quirk_stm32_pcie_limit_mrrs(struct pci_dev *pci)
+{
+	struct pci_dev *root_port;
+	struct pci_bus *bus = pci->bus;
+	int readrq;
+	int mps;
+
+	if (pci_is_root_bus(bus))
+		return;
+
+	root_port = pcie_find_root_port(pci);
+
+	if (!apply_mrrs_quirk(root_port))
+		return;
+
+	mps = pcie_get_mps(root_port);
+
+	/*
+	 * STM32 PCI controller has a h/w performance limitation on the AXI DDR requests.
+	 * Limit the maximum read request size to 256B on all downstream devices.
+	 */
+	readrq = pcie_get_readrq(pci);
+	if (readrq > 256) {
+		int mrrs = min(mps, 256);
+
+		pcie_set_readrq(pci, mrrs);
+
+		pci_info(pci, "Max Read Rq set to %4d (was %4d)\n", mrrs, readrq);
+	}
+}
+
+DECLARE_PCI_FIXUP_HEADER(PCI_ANY_ID, PCI_ANY_ID,
+			 quirk_stm32_pcie_limit_mrrs);
+
+static int stm32_dma_limit(struct pci_dev *pdev, void *data)
+{
+	dev_dbg(&pdev->dev, "set bus_dma_limit");
+
+	pdev->dev.bus_dma_limit = DMA_BIT_MASK(32);
+
+	return 0;
+}
+
+static void quirk_stm32_dma_mask(struct pci_dev *pci)
+{
+	struct pci_dev *root_port;
+
+	root_port = pcie_find_root_port(pci);
+
+	if (root_port && is_stm32_pcie_driver(root_port->dev.parent))
+		pci_walk_bus(pci->bus, stm32_dma_limit, NULL);
+}
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_SYNOPSYS, 0x0550, quirk_stm32_dma_mask);
+
+module_platform_driver(stm32_pcie_driver);
+
+MODULE_AUTHOR("Christian Bruel <christian.bruel@...s.st.com>");
+MODULE_DESCRIPTION("STM32MP25 PCIe Controller driver");
+MODULE_LICENSE("GPL");
+MODULE_DEVICE_TABLE(of, stm32_pcie_of_match);
diff --git a/drivers/pci/controller/dwc/pcie-stm32.h b/drivers/pci/controller/dwc/pcie-stm32.h
new file mode 100644
index 000000000000..7e9300bfddce
--- /dev/null
+++ b/drivers/pci/controller/dwc/pcie-stm32.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * ST PCIe driver definitions for STM32-MP25 SoC
+ *
+ * Copyright (C) 2024 STMicroelectronics - All Rights Reserved
+ * Author: Christian Bruel <christian.bruel@...s.st.com>
+ */
+
+#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_RC		BIT(10)
+#define STM32MP25_PCIECR_REQ_RETRY_EN	BIT(3)
+#define STM32MP25_PCIECR_LTSSM_EN	BIT(2)
+
+#define SYSCFG_PCIECR			0x6000
+#define SYSCFG_PCIEPMEMSICR		0x6004
+#define SYSCFG_PCIEAERRCMSICR		0x6008
+#define SYSCFG_PCIESR1			0x6100
+#define SYSCFG_PCIESR2			0x6104
+
+#define PCIE_CAP_MAX_PAYLOAD_SIZE(x)	((x) << 5)
+#define PCIE_CAP_MAX_READ_REQ_SIZE(x)	((x) << 12)
-- 
2.34.1

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