[PATCH 4/5] PCI: stm32: Add PCIe endpoint support for STM32MP25

Christian Bruel
2024-11-12T16:36:06Z

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@foss.st.com>
---
drivers/pci/controller/dwc/Kconfig | 12 +
drivers/pci/controller/dwc/Makefile | 1 +
drivers/pci/controller/dwc/pcie-stm32-ep.c | 433 +++++++++++++++++++++
3 files changed, 446 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 50a014c2dfd0..29b7f45f82c7 100644
--- a/drivers/pci/controller/dwc/Kconfig
+++ b/drivers/pci/controller/dwc/Kconfig
@@ -470,4 +470,16 @@ 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.
endmenu
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..9fc43046531d
--- /dev/null
+++ b/drivers/pci/controller/dwc/pcie-stm32-ep.c
@@ -0,0 +1,433 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * STMicroelectronics STM32MP25 PCIe endpoint driver.
+ *
+ * Copyright (C) 2024 STMicroelectronics
+ * Author: Christian Bruel <christian.bruel@foss.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"
+
+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 *reset_gpio;
+ enum stm32_pcie_ep_link_status link_status;
+ unsigned int perst_irq;
+};
+
+static const struct of_device_id stm32_pcie_ep_of_match[] = {
+ { .compatible = "st,stm32mp25-pcie-ep" },
+ {},
+};
+
+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 = 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;
+ }
+
+ return 0;
+}
+
+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);
+ pm_runtime_put_sync(dev);
+ return;
+ }
+
+ ret = dw_pcie_ep_init_registers(ep);
+ if (ret) {
+ dev_err(dev, "Failed to complete initialization: %d\n", ret);
+ stm32_pcie_disable_resources(stm32_pcie);
+ pm_runtime_put_sync(dev);
+ return;
+ }
+
+ pci_epc_init_notify(ep->epc);
+
+ ret = stm32_pcie_enable_link(pci);
+ if (ret) {
+ dev_err(dev, "PCIe Cannot establish link: %d\n", ret);
+ stm32_pcie_disable_resources(stm32_pcie);
+ pm_runtime_put_sync(dev);
+ return;
+ }
+
+ stm32_pcie->link_status = STM32_PCIE_EP_LINK_ENABLED;
+}
+
+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->reset_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);
+ pm_runtime_put_sync(dev);
+ return ret;
+ }
+
+ ret = stm32_pcie_enable_resources(stm32_pcie);
+ if (ret) {
+ dev_err(dev, "failed to enable resources: %d\n", ret);
+ dw_pcie_ep_deinit(ep);
+ pm_runtime_put_sync(dev);
+ return ret;
+ }
+
+ ret = dw_pcie_ep_init_registers(ep);
+ if (ret) {
+ dev_err(dev, "Failed to initialize DWC endpoint registers\n");
+ stm32_pcie_disable_resources(stm32_pcie);
+ dw_pcie_ep_deinit(ep);
+ pm_runtime_put_sync(dev);
+ return ret;
+ }
+
+ pci_epc_init_notify(ep->epc);
+
+ return 0;
+}
+
+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, "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");
+
+ stm32_pcie->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_IN);
+ if (IS_ERR(stm32_pcie->reset_gpio))
+ return dev_err_probe(dev, PTR_ERR(stm32_pcie->reset_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->reset_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 struct platform_driver stm32_pcie_ep_driver = {
+ .probe = stm32_pcie_probe,
+ .remove_new = 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@foss.st.com>");
+MODULE_DESCRIPTION("STM32MP25 PCIe Endpoint Controller driver");
+MODULE_LICENSE("GPL");
+MODULE_DEVICE_TABLE(of, stm32_pcie_ep_of_match);
--
2.34.1