[PATCH v3 2/2] pcie-xilinx: Support reset GPIO for PERST#

Mike Looijmans
2025-04-09T15:05:56Z

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@topic.nl>
---

Changes in v3:
Include linux/gpio/consumer.h
Message "Failed to request reset GPIO"
Use PCIE_T_PVPERL_MS and PCIE_T_RRS_READY_MS
Dropped dt-bindings patch, not needed

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..8e8ca9891b36 100644
--- a/drivers/pci/controller/pcie-xilinx.c
+++ b/drivers/pci/controller/pcie-xilinx.c
@@ -10,6 +10,7 @@
* ARM PCI Host generic driver.
*/

+#include <linux/gpio/consumer.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqdomain.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),
+ "Failed to request reset GPIO\n");
+
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) {
+ msleep(PCIE_T_PVPERL_MS); /* Minimum assertion time */
+ gpiod_set_value_cansleep(perst_gpio, 0);
+ /* Initial delay to provide endpoint time to initialize */
+ msleep(PCIE_T_RRS_READY_MS);
+ }
+
xilinx_pcie_init_port(pcie);

err = xilinx_pcie_init_irq_domain(pcie);
--
2.43.0