[PATCH] gpio: omap: Honor "aliases" node

[Alexander Sverdlin <alexander.sverdlin@gmail.com>]

Currently the naming of the GPIO chips depends on their order in the DT,
but also on the kernel version (I've noticed the change from v5.10.x to
v5.11). Honor the persistent enumeration in the "aliases" node like other
GPIO drivers do.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
---
Yes, I noticed checkpatch "WARNING: DT binding docs and includes should be
a separate patch."
However, the parts below are tiny and barely make sense separately.

 Documentation/devicetree/bindings/gpio/gpio-omap.txt | 6 ++++++
 drivers/gpio/gpio-omap.c                             | 5 +++++
 2 files changed, 11 insertions(+)

diff --git a/Documentation/devicetree/bindings/gpio/gpio-omap.txt b/Documentation/devicetree/bindings/gpio/gpio-omap.txt
index e57b2cb28f6c..6050db3fd84e 100644
--- a/Documentation/devicetree/bindings/gpio/gpio-omap.txt
+++ b/Documentation/devicetree/bindings/gpio/gpio-omap.txt
@@ -30,9 +30,15 @@ OMAP specific properties:
 - ti,gpio-always-on: 	Indicates if a GPIO bank is always powered and
 			so will never lose its logic state.
 
+Note: GPIO ports can have an alias correctly numbered in "aliases" node for
+persistent enumeration.
 
 Example:
 
+aliases {
+	gpio0 = &gpio0;
+};
+
 gpio0: gpio@44e07000 {
     compatible = "ti,omap4-gpio";
     reg = <0x44e07000 0x1000>;
diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
index 41952bb818ad..dd2a8f6d920f 100644
--- a/drivers/gpio/gpio-omap.c
+++ b/drivers/gpio/gpio-omap.c
@@ -1014,6 +1014,11 @@ static int omap_gpio_chip_init(struct gpio_bank *bank, struct irq_chip *irqc)
 			bank->chip.parent = &omap_mpuio_device.dev;
 		bank->chip.base = OMAP_MPUIO(0);
 	} else {
+#ifdef CONFIG_OF_GPIO
+		ret = of_alias_get_id(bank->chip.of_node, "gpio");
+		if (ret >= 0)
+			gpio = ret * bank->width;
+#endif
 		label = devm_kasprintf(bank->chip.parent, GFP_KERNEL, "gpio-%d-%d",
 				       gpio, gpio + bank->width - 1);
 		if (!label)
-- 
2.30.1