[PATCH v5 4/9 RESEND] PCI: stm32: Add PCIe Endpoint support for STM32MP25

Christian Bruel posted 9 patches 8 months, 4 weeks ago
There is a newer version of this series
[PATCH v5 4/9 RESEND] PCI: stm32: Add PCIe Endpoint support for STM32MP25
Posted by Christian Bruel 8 months, 4 weeks ago
Add driver to configure the STM32MP25 SoC PCIe Gen1 2.5GT/s or Gen2 5GT/s
controller based on the DesignWare PCIe core in endpoint mode.

Uses the common reference clock provided by the host.

The PCIe core_clk receives the pipe0_clk from the ComboPHY as input,
and the ComboPHY PLL must be locked for pipe0_clk to be ready.
Consequently, PCIe core registers cannot be accessed until the ComboPHY is
fully initialised and refclk is enabled and ready.

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 | 420 +++++++++++++++++++++
 drivers/pci/controller/dwc/pcie-stm32.h    |   1 +
 4 files changed, 434 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..4a3eb838557c 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
+	  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..a8e9c5a9b127
--- /dev/null
+++ b/drivers/pci/controller/dwc/pcie-stm32-ep.c
@@ -0,0 +1,420 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * STMicroelectronics STM32MP25 PCIe endpoint driver.
+ *
+ * Copyright (C) 2025 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 *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);
+	enum pci_barno bar;
+
+	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++)
+		dw_pcie_ep_reset_bar(pci, bar);
+}
+
+static int stm32_pcie_enable_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,
+			   STM32MP25_PCIECR_LTSSM_EN);
+
+	return dw_pcie_wait_for_link(pci);
+}
+
+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_LTSSM_EN, 0);
+}
+
+static int stm32_pcie_start_link(struct dw_pcie *pci)
+{
+	struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci);
+	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 0;
+	}
+
+	ret = stm32_pcie_enable_link(pci);
+	if (ret) {
+		dev_err(pci->dev, "PCIe cannot establish link: %d\n", ret);
+		return ret;
+	}
+
+	dw_pcie_ep_linkup(ep);
+
+	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 = SZ_64K,
+};
+
+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_pm_put_sync;
+	}
+
+	ret = dw_pcie_ep_init_registers(ep);
+	if (ret) {
+		dev_err(dev, "Failed to complete initialization: %d\n", ret);
+		goto err_disable_resources;
+	}
+
+	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_deinit_notify;
+	}
+
+	stm32_pcie->link_status = STM32_PCIE_EP_LINK_ENABLED;
+
+	return;
+
+err_deinit_notify:
+	pci_epc_deinit_notify(ep->epc);
+
+err_disable_resources:
+	stm32_pcie_disable_resources(stm32_pcie);
+
+err_pm_put_sync:
+	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_ep *ep = &stm32_pcie->pci.ep;
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	ret = pm_runtime_resume_and_get(dev);
+	if (ret < 0) {
+		dev_err(dev, "pm runtime resume failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = regmap_update_bits(stm32_pcie->regmap, SYSCFG_PCIECR,
+				 STM32MP25_PCIECR_TYPE_MASK,
+				 STM32MP25_PCIECR_EP);
+	if (ret) {
+		goto err_pm_put_sync;
+		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_pm_put_sync;
+	}
+
+	ret = stm32_pcie_enable_resources(stm32_pcie);
+	if (ret) {
+		dev_err(dev, "failed to enable resources: %d\n", ret);
+		goto err_ep_deinit;
+	}
+
+	ret = dw_pcie_ep_init_registers(ep);
+	if (ret) {
+		dev_err(dev, "Failed to initialize DWC endpoint registers\n");
+		goto err_disable_resources;
+	}
+
+	pci_epc_init_notify(ep->epc);
+
+	return 0;
+
+err_disable_resources:
+	stm32_pcie_disable_resources(stm32_pcie);
+
+err_ep_deinit:
+	dw_pcie_ep_deinit(ep);
+
+err_pm_put_sync:
+	pm_runtime_put_sync(dev);
+	return ret;
+}
+
+static int stm32_pcie_probe(struct platform_device *pdev)
+{
+	struct stm32_pcie *stm32_pcie;
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	stm32_pcie = devm_kzalloc(dev, sizeof(*stm32_pcie), GFP_KERNEL);
+	if (!stm32_pcie)
+		return -ENOMEM;
+
+	stm32_pcie->pci.dev = dev;
+	stm32_pcie->pci.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, NULL);
+	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@foss.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 387112c4e42c..09d39f04e469 100644
--- a/drivers/pci/controller/dwc/pcie-stm32.h
+++ b/drivers/pci/controller/dwc/pcie-stm32.h
@@ -9,6 +9,7 @@
 #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_RC		BIT(10)
 
-- 
2.34.1
Re: [PATCH v5 4/9 RESEND] PCI: stm32: Add PCIe Endpoint support for STM32MP25
Posted by Manivannan Sadhasivam 8 months, 1 week ago
On Tue, Mar 25, 2025 at 07:59:30AM +0100, Christian Bruel wrote:
> Add driver to configure the STM32MP25 SoC PCIe Gen1 2.5GT/s or Gen2 5GT/s
> controller based on the DesignWare PCIe core in endpoint mode.
> 
> Uses the common reference clock provided by the host.
> 
> The PCIe core_clk receives the pipe0_clk from the ComboPHY as input,
> and the ComboPHY PLL must be locked for pipe0_clk to be ready.
> Consequently, PCIe core registers cannot be accessed until the ComboPHY is
> fully initialised and refclk is enabled and ready.
> 
> 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 | 420 +++++++++++++++++++++
>  drivers/pci/controller/dwc/pcie-stm32.h    |   1 +
>  4 files changed, 434 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..4a3eb838557c 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
> +	  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..a8e9c5a9b127
> --- /dev/null
> +++ b/drivers/pci/controller/dwc/pcie-stm32-ep.c
> @@ -0,0 +1,420 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * STMicroelectronics STM32MP25 PCIe endpoint driver.
> + *
> + * Copyright (C) 2025 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 *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);
> +	enum pci_barno bar;
> +
> +	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++)
> +		dw_pcie_ep_reset_bar(pci, bar);
> +}
> +
> +static int stm32_pcie_enable_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,
> +			   STM32MP25_PCIECR_LTSSM_EN);
> +
> +	return dw_pcie_wait_for_link(pci);
> +}
> +
> +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_LTSSM_EN, 0);
> +}
> +
> +static int stm32_pcie_start_link(struct dw_pcie *pci)
> +{
> +	struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci);
> +	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 0;
> +	}
> +
> +	ret = stm32_pcie_enable_link(pci);
> +	if (ret) {
> +		dev_err(pci->dev, "PCIe cannot establish link: %d\n", ret);
> +		return ret;
> +	}
> +
> +	dw_pcie_ep_linkup(ep);
> +

This callback should only be used when the epc_features::linkup_notifier flag is
set. That only applies to platforms supporting LINK_UP interrupt. In this case,
once the start_link() callback returns, it is assumed that the link is active.
So no need to call dw_pcie_ep_linkup().

> +	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 = SZ_64K,
> +};
> +
> +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.

Make use of 80 columns.

> +	 */
> +	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_pm_put_sync;
> +	}
> +
> +	ret = dw_pcie_ep_init_registers(ep);
> +	if (ret) {
> +		dev_err(dev, "Failed to complete initialization: %d\n", ret);
> +		goto err_disable_resources;
> +	}
> +
> +	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_deinit_notify;
> +	}

Link is supposed to be enabled only by the start_link() callback.

> +
> +	stm32_pcie->link_status = STM32_PCIE_EP_LINK_ENABLED;
> +
> +	return;
> +
> +err_deinit_notify:
> +	pci_epc_deinit_notify(ep->epc);
> +
> +err_disable_resources:
> +	stm32_pcie_disable_resources(stm32_pcie);
> +
> +err_pm_put_sync:
> +	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_ep *ep = &stm32_pcie->pci.ep;
> +	struct device *dev = &pdev->dev;
> +	int ret;
> +
> +	ret = pm_runtime_resume_and_get(dev);
> +	if (ret < 0) {
> +		dev_err(dev, "pm runtime resume failed: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = regmap_update_bits(stm32_pcie->regmap, SYSCFG_PCIECR,
> +				 STM32MP25_PCIECR_TYPE_MASK,
> +				 STM32MP25_PCIECR_EP);
> +	if (ret) {
> +		goto err_pm_put_sync;
> +		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_pm_put_sync;
> +	}
> +
> +	ret = stm32_pcie_enable_resources(stm32_pcie);
> +	if (ret) {
> +		dev_err(dev, "failed to enable resources: %d\n", ret);
> +		goto err_ep_deinit;
> +	}
> +
> +	ret = dw_pcie_ep_init_registers(ep);
> +	if (ret) {
> +		dev_err(dev, "Failed to initialize DWC endpoint registers\n");
> +		goto err_disable_resources;
> +	}
> +
> +	pci_epc_init_notify(ep->epc);
> +

You are calling dw_pcie_ep_init_registers() and  pci_epc_init_notify() from 2
places. I think the one in stm32_pcie_perst_deassert() should be dropped since
the DBI registers are available at this point itself.

- Mani

-- 
மணிவண்ணன் சதாசிவம்
Re: [PATCH v5 4/9 RESEND] PCI: stm32: Add PCIe Endpoint support for STM32MP25
Posted by Christian Bruel 8 months, 1 week ago

On 4/9/25 10:03, Manivannan Sadhasivam wrote:
> On Tue, Mar 25, 2025 at 07:59:30AM +0100, Christian Bruel wrote:
>> Add driver to configure the STM32MP25 SoC PCIe Gen1 2.5GT/s or Gen2 5GT/s
>> controller based on the DesignWare PCIe core in endpoint mode.
>>
>> Uses the common reference clock provided by the host.
>>
>> The PCIe core_clk receives the pipe0_clk from the ComboPHY as input,
>> and the ComboPHY PLL must be locked for pipe0_clk to be ready.
>> Consequently, PCIe core registers cannot be accessed until the ComboPHY is
>> fully initialised and refclk is enabled and ready.
>>
>> 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 | 420 +++++++++++++++++++++
>>   drivers/pci/controller/dwc/pcie-stm32.h    |   1 +
>>   4 files changed, 434 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..4a3eb838557c 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
>> +	  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..a8e9c5a9b127
>> --- /dev/null
>> +++ b/drivers/pci/controller/dwc/pcie-stm32-ep.c
>> @@ -0,0 +1,420 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * STMicroelectronics STM32MP25 PCIe endpoint driver.
>> + *
>> + * Copyright (C) 2025 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 *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);
>> +	enum pci_barno bar;
>> +
>> +	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++)
>> +		dw_pcie_ep_reset_bar(pci, bar);
>> +}
>> +
>> +static int stm32_pcie_enable_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,
>> +			   STM32MP25_PCIECR_LTSSM_EN);
>> +
>> +	return dw_pcie_wait_for_link(pci);
>> +}
>> +
>> +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_LTSSM_EN, 0);
>> +}
>> +
>> +static int stm32_pcie_start_link(struct dw_pcie *pci)
>> +{
>> +	struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci);
>> +	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 0;
>> +	}
>> +
>> +	ret = stm32_pcie_enable_link(pci);
>> +	if (ret) {
>> +		dev_err(pci->dev, "PCIe cannot establish link: %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	dw_pcie_ep_linkup(ep);
>> +
> 
> This callback should only be used when the epc_features::linkup_notifier flag is
> set. That only applies to platforms supporting LINK_UP interrupt. In this case,
> once the start_link() callback returns, it is assumed that the link is active.
> So no need to call dw_pcie_ep_linkup().

OK thank you

> 
>> +	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 = SZ_64K,
>> +};
>> +
>> +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.
> 
> Make use of 80 columns.
> 
>> +	 */
>> +	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_pm_put_sync;
>> +	}
>> +
>> +	ret = dw_pcie_ep_init_registers(ep);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to complete initialization: %d\n", ret);
>> +		goto err_disable_resources;
>> +	}
>> +
>> +	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_deinit_notify;
>> +	}
> 
> Link is supposed to be enabled only by the start_link() callback.

OK. and then I need to remove the IRQ_NOAUTOEN for perst_irq, which make 
the link_status unnecessary and results in simplifications. thank you

> 
>> +
>> +	stm32_pcie->link_status = STM32_PCIE_EP_LINK_ENABLED;
>> +
>> +	return;
>> +
>> +err_deinit_notify:
>> +	pci_epc_deinit_notify(ep->epc);
>> +
>> +err_disable_resources:
>> +	stm32_pcie_disable_resources(stm32_pcie);
>> +
>> +err_pm_put_sync:
>> +	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_ep *ep = &stm32_pcie->pci.ep;
>> +	struct device *dev = &pdev->dev;
>> +	int ret;
>> +
>> +	ret = pm_runtime_resume_and_get(dev);
>> +	if (ret < 0) {
>> +		dev_err(dev, "pm runtime resume failed: %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	ret = regmap_update_bits(stm32_pcie->regmap, SYSCFG_PCIECR,
>> +				 STM32MP25_PCIECR_TYPE_MASK,
>> +				 STM32MP25_PCIECR_EP);
>> +	if (ret) {
>> +		goto err_pm_put_sync;
>> +		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_pm_put_sync;
>> +	}
>> +
>> +	ret = stm32_pcie_enable_resources(stm32_pcie);
>> +	if (ret) {
>> +		dev_err(dev, "failed to enable resources: %d\n", ret);
>> +		goto err_ep_deinit;
>> +	}
>> +
>> +	ret = dw_pcie_ep_init_registers(ep);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to initialize DWC endpoint registers\n");
>> +		goto err_disable_resources;
>> +	}
>> +
>> +	pci_epc_init_notify(ep->epc);
>> +
> 
> You are calling dw_pcie_ep_init_registers() and  pci_epc_init_notify() from 2
> places. I think the one in stm32_pcie_perst_deassert() should be dropped since
> the DBI registers are available at this point itself.

The DBI registers need to be rewritten as a results of phy_init() 
resetting the PCIe core on RCC phy_reset :
RCC phy_reset is connected to power_up_rst_n, causing the PCIe logic to 
be reset when it should not be for a warm reset.
I will document this bug in this part of the code.

Christian


> 
> - Mani
>