[PATCH RFT] pci: imx: Properly support upstream Linux reset-gpios property

[Krzysztof Kozlowski]

The driver requests explicitly "reset-gpio" property, not the one with
"gpios" suffix but upstream Linux kernel deprecated it in 2021.
Existing upstream Linux kernel DTS is being changed to "reset-gpios"
property, thus update the driver to read that one too.

Note that driver is probably broken already, because it parsed GPIO in
standard way respecting the flags and on top of that applied the
"reset-gpio-active-high" flag, thus "reset-gpio ACTIVE_LOW" with the
"reset-gpio-active-high" property would be double inverted.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxxxxx>

---

1. https://lore.kernel.org/linux-devicetree/20260312-dts-snps-reset-gpios-v2-12-0d5040eb4a1e@xxxxxxxxxxxxxxxx/
2. See Linux kernel commit 42694f9f6407 ("dt-bindings: PCI: add snps,dw-pcie.yaml")
---
 drivers/pci/pcie_imx.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/pcie_imx.c b/drivers/pci/pcie_imx.c
index 11c4ccbfc555..8d853ecf2c22 100644
--- a/drivers/pci/pcie_imx.c
+++ b/drivers/pci/pcie_imx.c
@@ -728,15 +728,31 @@ static int imx_pcie_dm_write_config(struct udevice *dev, pci_dev_t bdf,
 static int imx_pcie_dm_probe(struct udevice *dev)
 {
 	struct imx_pcie_priv *priv = dev_get_priv(dev);
+	int ret;
 
 #if CONFIG_IS_ENABLED(DM_REGULATOR)
 	device_get_supply_regulator(dev, "vpcie-supply", &priv->vpcie);
 #endif
 
 	/* if PERST# valid from dt then assert it */
-	gpio_request_by_name(dev, "reset-gpio", 0, &priv->reset_gpio,
-			     GPIOD_IS_OUT);
-	priv->reset_active_high = dev_read_bool(dev, "reset-gpio-active-high");
+	ret = gpio_request_by_name(dev, "reset-gpio", 0, &priv->reset_gpio,
+				   GPIOD_IS_OUT);
+	if (!ret) {
+		/*
+		 * Legacy property, invert assert logic based on
+		 * reset-gpio-active-high. This won't work if flags are not
+		 * matching the reset-gpio-active-high.
+		 */
+		priv->reset_active_high = dev_read_bool(dev, "reset-gpio-active-high");
+	} else {
+		/*
+		 * Linux kernel upstream property, assert active level based on
+		 * GPIO flags, thus leave priv->reset_active_high=0.
+		 */
+		gpio_request_by_name(dev, "reset-gpios", 0, &priv->reset_gpio,
+				     GPIOD_IS_OUT);
+	}
+
 	if (dm_gpio_is_valid(&priv->reset_gpio)) {
 		dm_gpio_set_value(&priv->reset_gpio,
 				  priv->reset_active_high ? 0 : 1);
-- 
2.51.0