gpio-omap: ensure a stable gpio numbering

Traditionally the n-th gpio device probed by the omap gpio driver got the gpio number range [n*32 .. n*32+31].
When order of the devices probed by the driver changes (which can happen already now when some devices have a pinctrl and so the first probe attempt returns -ENODEV) the numbering changes.

To ensure a deterministical numbering use of_alias_get_id to determine the base for a given device. If no respective alias exists fall back to the traditional numbering.

For the unusual case where only a part of the gpio devices have a matching alias some of them might fail to probe. But if none of them has an alias or all, there is no conflict which should be good enough to maintain backward compatibility.

Traditionally the n-th gpio device probed by the omap gpio driver got the gpio number range [n*32 .. n*32+31].
When order of the devices probed by the driver changes (which can happen already now when some devices have a pinctrl and so the first probe attempt returns -ENODEV) the numbering changes.

To ensure a deterministical numbering use of_alias_get_id to determine the base for a given device. If no respective alias exists fall back to the traditional numbering.

For the unusual case where only a part of the gpio devices have a matching alias some of them might fail to probe. But if none of them has an alias or all, there is no conflict which should be good enough to maintain backward compatibility.

Signed-off-by Uwe Kleine-K?nig <[email protected]>

---
  drivers/gpio/gpio-omap.c | 19 ++++++++++++++++++-
  1 file changed, 18 insertions(+), 1 deletion(-)

drivers/gpio/gpio-omap.c +12 -1

index b98ede78c9d8..4d91792e7266 100644
@@ -1053,9 +1053,26 @@ 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 {
+		int gpio_alias_id __maybe_unused;
+
  		bank->chip.label = "gpio";
-		bank->chip.base = gpio;
+
+#if defined(CONFIG_OF_GPIO)
+		/*
+		 * Traditionally the base is given out in first-come-first-serve
+		 * order.  This might shuffle the numbering of gpios if the
+		 * probe order changes.  So make the base deterministical if the
+		 * device tree specifies alias ids.
+		 */
+		gpio_alias_id = of_alias_get_id(bank->chip.of_node, "gpio");
+		if (gpio_alias_id >= 0)

Traditionally the n-th gpio device probed by the omap gpio driver got the gpio number range [n*32 .. n*32+31].
When order of the devices probed by the driver changes (which can happen already now when some devices have a pinctrl and so the first probe attempt returns -ENODEV) the numbering changes.

To ensure a deterministical numbering use of_alias_get_id to determine the base for a given device. If no respective alias exists fall back to the traditional numbering.

For the unusual case where only a part of the gpio devices have a matching alias some of them might fail to probe. But if none of them has an alias or all, there is no conflict which should be good enough to maintain backward compatibility.

Signed-off-by Uwe Kleine-K?nig <[email protected]>

---
 drivers/gpio/gpio-omap.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

drivers/gpio/gpio-omap.c +9 -1

index b98ede78c9d8..4d91792e7266 100644
@@ -1053,9 +1053,26 @@ 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 {
+               int gpio_alias_id __maybe_unused;
+
                bank->chip.label = "gpio";
-               bank->chip.base = gpio;
+
+#if defined(CONFIG_OF_GPIO)
+               /*
+                * Traditionally the base is given out in first-come-first-serve
+                * order.  This might shuffle the numbering of gpios if the
+                * probe order changes.  So make the base deterministical if the
+                * device tree specifies alias ids.