Re: [PATCH v2 4/5] PCI: stm32: Add PCIe endpoint support for STM32MP25

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Tue, Nov 26, 2024 at 04:51:18PM +0100, Christian Bruel wrote:

[...]

> +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;
> +	}

How the REFCLK is supplied to the endpoint? From host or generated locally?

> +
> +	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,

Use SZ_64K

> +};
> +

[...]

> +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;
> +	}

You might want to do runtime resume before accessing regmap.

> +
> +	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;

Why can't you allocate it statically inside 'struct stm32_pcie'?

> +
> +	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);

Hmm, so PHY mode is common for both endpoint and host?

- Mani

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