[PATCH v2 3/3] pcie-xilinx: Support reset GPIO for PERST#

[Manivannan Sadhasivam]

On Tue, Mar 25, 2025 at 08:18:27AM +0100, Mike Looijmans wrote:
> Support providing the PERST# reset signal through a devicetree binding.
> Thus the system no longer relies on external components to perform the
> bus reset.
> 
> Signed-off-by: Mike Looijmans <mike.looijmans at topic.nl>
> ---
> 
> Changes in v2:
> Split into "reset GPIO" and "wait for link" patches
> Handle GPIO defer and/or errors
> 
>  drivers/pci/controller/pcie-xilinx.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/pci/controller/pcie-xilinx.c b/drivers/pci/controller/pcie-xilinx.c
> index 2e59b91f43e0..e191ab95d669 100644
> --- a/drivers/pci/controller/pcie-xilinx.c
> +++ b/drivers/pci/controller/pcie-xilinx.c
> @@ -18,6 +18,7 @@
>  #include <linux/iopoll.h>
>  #include <linux/msi.h>
>  #include <linux/of_address.h>
> +#include <linux/of_gpio.h>

Correct header is:

#include <linux/gpio/consumer.h>

>  #include <linux/of_pci.h>
>  #include <linux/of_platform.h>
>  #include <linux/of_irq.h>
> @@ -577,11 +578,17 @@ static int xilinx_pcie_probe(struct platform_device *pdev)
>  	struct device *dev = &pdev->dev;
>  	struct xilinx_pcie *pcie;
>  	struct pci_host_bridge *bridge;
> +	struct gpio_desc *perst_gpio;
>  	int err;
>  
>  	if (!dev->of_node)
>  		return -ENODEV;
>  
> +	perst_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(perst_gpio))
> +		return dev_err_probe(dev, PTR_ERR(perst_gpio),
> +				     "reset-gpios request failed\n");

'Failed to request reset GPIO'

> +
>  	bridge = devm_pci_alloc_host_bridge(dev, sizeof(*pcie));
>  	if (!bridge)
>  		return -ENODEV;
> @@ -596,6 +603,13 @@ static int xilinx_pcie_probe(struct platform_device *pdev)
>  		return err;
>  	}
>  
> +	if (perst_gpio) {
> +		usleep_range(10, 20); /* Assert the reset for ~10 us */

Delay should be PCIE_T_PVPERL_MS.

> +		gpiod_set_value_cansleep(perst_gpio, 0);
> +		/* Initial delay to provide endpoint time to restart */

s/restart/initialize

- Mani

-- 
மணிவண்ணன் சதாசிவம்