On Tue, Jun 10, 2025 at 11:07:07AM +0200, Christian Bruel wrote:
> Add driver for the STM32MP25 SoC PCIe Gen1 2.5 GT/s and Gen2 5GT/s
> controller based on the DesignWare PCIe core.
> ...
> +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;
> + struct gpio_desc *wake_gpio;
> +};
> +
> +static void stm32_pcie_deassert_perst(struct stm32_pcie *stm32_pcie)
> +{
> + /* Delay PERST# de-assertion until the power stabilizes */
> + msleep(PCIE_T_PVPERL_MS);
> +
> + gpiod_set_value(stm32_pcie->perst_gpio, 0);
> +
> + /* Wait for the REFCLK to stabilize */
> + if (stm32_pcie->perst_gpio)
> + msleep(PCIE_T_RRS_READY_MS);
This obviously relies on gpiod_set_value(stm32_pcie->perst_gpio, 0)
being a no-op when perst_gpio == NULL. Since we're testing perst_gpio
anyway, I think it might be more readable to avoid relying on
gpiod_set_value() being a no-op:
msleep(PCIE_T_PVPERL_MS);
if (stm32_pcie->perst_gpio) {
gpiod_set_value(stm32_pcie->perst_gpio, 0);
msleep(PCIE_T_RRS_READY_MS);
}
(And a similar change in stm32_pcie_assert_perst())
But this seems wrong because PCIE_T_PVPERL_MS is a delay before PERST#
is deasserted, but when perst_gpio == NULL, PERST# has already *been*
deasserted.
So it seems like it would make more sense as:
if (stm32_pcie->perst_gpio) {
msleep(PCIE_T_PVPERL_MS);
gpiod_set_value(stm32_pcie->perst_gpio, 0);
}
msleep(PCIE_T_RRS_READY_MS);
> +}
> +
> +static void stm32_pcie_assert_perst(struct stm32_pcie *stm32_pcie)
> +{
> + gpiod_set_value(stm32_pcie->perst_gpio, 1);
> +}
> +
> +static int stm32_pcie_start_link(struct dw_pcie *pci)
> +{
> + struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci);
> +
> + return regmap_update_bits(stm32_pcie->regmap, SYSCFG_PCIECR,
> + STM32MP25_PCIECR_LTSSM_EN,
> + STM32MP25_PCIECR_LTSSM_EN);
> +}
> +
> +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);
> +}
> +
> +static int stm32_pcie_suspend_noirq(struct device *dev)
> +{
> + struct stm32_pcie *stm32_pcie = dev_get_drvdata(dev);
> + int ret;
> +
> + ret = dw_pcie_suspend_noirq(&stm32_pcie->pci);
> + if (ret)
> + return ret;
> +
> + stm32_pcie_assert_perst(stm32_pcie);
> +
> + clk_disable_unprepare(stm32_pcie->clk);
> +
> + if (!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);
> + int ret;
> +
> + /*
> + * The core clock is gated with CLKREQ# from the COMBOPHY REFCLK,
> + * thus if no device is present, must force it low with an init pinmux
> + * to be able to access the DBI registers.
What happens on initial probe if no device is present? I assume we
access DBI registers in the dw_pcie_host_init() path, and it seems
like we'd have the same issue with DBI not being accessible when no
device is present.
> + 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_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 err_phy_exit;
> +
> + stm32_pcie_deassert_perst(stm32_pcie);
> +
> + ret = dw_pcie_resume_noirq(&stm32_pcie->pci);
> + if (ret)
> + goto err_disable_clk;
> +
> + pinctrl_pm_select_default_state(dev);
> +
> + return 0;
> +
> +err_disable_clk:
> + stm32_pcie_assert_perst(stm32_pcie);
> + clk_disable_unprepare(stm32_pcie->clk);
> +
> +err_phy_exit:
> + 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)
> +};
> +
> +static const struct dw_pcie_host_ops stm32_pcie_host_ops = {
> +};
> +
> +static const struct dw_pcie_ops dw_pcie_ops = {
> + .start_link = stm32_pcie_start_link,
> + .stop_link = stm32_pcie_stop_link
> +};
> +
> +static int stm32_add_pcie_port(struct stm32_pcie *stm32_pcie)
> +{
> + struct device *dev = stm32_pcie->pci.dev;
> + unsigned int wake_irq;
> + int ret;
> +
> + /* Start to enable resources with PERST# asserted */
I guess if device tree doesn't describe PERST#, we assume PERST# is
actually *deasserted* already at this point (because
stm32_pcie_deassert_perst() does nothing other than the delay)?
> + 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 err_phy_exit;
> +
> + stm32_pcie_deassert_perst(stm32_pcie);
> +
> + if (stm32_pcie->wake_gpio) {
> + wake_irq = gpiod_to_irq(stm32_pcie->wake_gpio);
> + ret = dev_pm_set_dedicated_wake_irq(dev, wake_irq);
> + if (ret) {
> + dev_err(dev, "Failed to enable wakeup irq %d\n", ret);
> + goto err_assert_perst;
> + }
> + irq_set_irq_type(wake_irq, IRQ_TYPE_EDGE_FALLING);
> + }
> +
> + return 0;
> +
> +err_assert_perst:
> + stm32_pcie_assert_perst(stm32_pcie);
> +
> +err_phy_exit:
> + phy_exit(stm32_pcie->phy);
> +
> + return ret;
> +}
> +
> +static void stm32_remove_pcie_port(struct stm32_pcie *stm32_pcie)
> +{
> + dev_pm_clear_wake_irq(stm32_pcie->pci.dev);
> +
> + stm32_pcie_assert_perst(stm32_pcie);
> +
> + phy_exit(stm32_pcie->phy);
> +}
> +
> +static int stm32_pcie_parse_port(struct stm32_pcie *stm32_pcie)
> +{
> + struct device *dev = stm32_pcie->pci.dev;
> + struct device_node *root_port;
> +
> + root_port = of_get_next_available_child(dev->of_node, NULL);
> +
> + stm32_pcie->phy = devm_of_phy_get(dev, root_port, NULL);
> + if (IS_ERR(stm32_pcie->phy)) {
> + of_node_put(root_port);
> + return dev_err_probe(dev, PTR_ERR(stm32_pcie->phy),
> + "Failed to get pcie-phy\n");
> + }
> +
> + stm32_pcie->perst_gpio = devm_fwnode_gpiod_get(dev, of_fwnode_handle(root_port),
> + "reset", GPIOD_OUT_HIGH, NULL);
> + if (IS_ERR(stm32_pcie->perst_gpio)) {
> + if (PTR_ERR(stm32_pcie->perst_gpio) != -ENOENT) {
> + of_node_put(root_port);
> + return dev_err_probe(dev, PTR_ERR(stm32_pcie->perst_gpio),
> + "Failed to get reset GPIO\n");
> + }
> + stm32_pcie->perst_gpio = NULL;
This looks like perst_gpio is optional in device tree? Is that really
the case? It seems hard to ensure we have the PCIE_T_PVPERL_MS and
PCIE_T_RRS_READY_MS delays in the right place if we don't have
perst_gpio.
> + }
> +
> + stm32_pcie->wake_gpio = devm_fwnode_gpiod_get(dev, of_fwnode_handle(root_port),
> + "wake", GPIOD_IN, NULL);
> +
> + if (IS_ERR(stm32_pcie->wake_gpio)) {
> + if (PTR_ERR(stm32_pcie->wake_gpio) != -ENOENT) {
> + of_node_put(root_port);
> + return dev_err_probe(dev, PTR_ERR(stm32_pcie->wake_gpio),
> + "Failed to get wake GPIO\n");
> + }
> + stm32_pcie->wake_gpio = NULL;
> + }
> +
> + of_node_put(root_port);
> +
> + return 0;
> +}
> +
> +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->pci.pp.ops = &stm32_pcie_host_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->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");
> +
> + ret = stm32_pcie_parse_port(stm32_pcie);
> + if (ret)
> + return ret;
> +
> + platform_set_drvdata(pdev, stm32_pcie);
> +
> + ret = stm32_add_pcie_port(stm32_pcie);
> + if (ret)
> + return ret;
> +
> + 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 err_remove_port;
> + }
> +
> + ret = pm_runtime_set_active(dev);
> + if (ret < 0) {
> + clk_disable_unprepare(stm32_pcie->clk);
> + stm32_remove_pcie_port(stm32_pcie);
> + return dev_err_probe(dev, ret, "Failed to activate runtime PM\n");
> + }
> +
> + pm_runtime_no_callbacks(dev);
> +
> + ret = devm_pm_runtime_enable(dev);
> + if (ret < 0) {
> + clk_disable_unprepare(stm32_pcie->clk);
> + stm32_remove_pcie_port(stm32_pcie);
> + return dev_err_probe(dev, ret, "Failed to enable runtime PM\n");
> + }
> +
> + ret = dw_pcie_host_init(&stm32_pcie->pci.pp);
> + if (ret)
> + goto err_disable_clk;
> +
> + if (stm32_pcie->wake_gpio)
> + device_init_wakeup(dev, true);
> +
> + return 0;
> +
> +err_disable_clk:
> + clk_disable_unprepare(stm32_pcie->clk);
> +
> +err_remove_port:
> + stm32_remove_pcie_port(stm32_pcie);
> +
> + return ret;
> +}
> +
> +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);
> +
> + stm32_remove_pcie_port(stm32_pcie);
> +
> + pm_runtime_put_noidle(&pdev->dev);
> +}
> +
> +static const struct of_device_id stm32_pcie_of_match[] = {
> + { .compatible = "st,stm32mp25-pcie-rc" },
> + {},
> +};
> +
> +static struct platform_driver stm32_pcie_driver = {
> + .probe = stm32_pcie_probe,
> + .remove = stm32_pcie_remove,
> + .driver = {
> + .name = "stm32-pcie",
> + .of_match_table = stm32_pcie_of_match,
> + .pm = &stm32_pcie_pm_ops,
> + .probe_type = PROBE_PREFER_ASYNCHRONOUS,
> + },
> +};
> +
> +module_platform_driver(stm32_pcie_driver);
> +
> +MODULE_AUTHOR("Christian Bruel <christian.bruel@xxxxxxxxxxx>");
> +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..387112c4e42c
> --- /dev/null
> +++ b/drivers/pci/controller/dwc/pcie-stm32.h
> @@ -0,0 +1,15 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * ST PCIe driver definitions for STM32-MP25 SoC
> + *
> + * Copyright (C) 2025 STMicroelectronics - All Rights Reserved
> + * Author: Christian Bruel <christian.bruel@xxxxxxxxxxx>
> + */
> +
> +#define to_stm32_pcie(x) dev_get_drvdata((x)->dev)
> +
> +#define STM32MP25_PCIECR_TYPE_MASK GENMASK(11, 8)
> +#define STM32MP25_PCIECR_LTSSM_EN BIT(2)
> +#define STM32MP25_PCIECR_RC BIT(10)
> +
> +#define SYSCFG_PCIECR 0x6000
> --
> 2.34.1
>
