[PATCH] gpio: Add gpio alias support

[haibo.chen@nxp.com]

From: Haibo Chen <haibo.chen@nxp.com>

This patch allow setting gpio device id via device tree alias.

Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
---
 drivers/gpio/gpiolib.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 56d090258d62..3d24351a33db 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -495,7 +495,7 @@ static void gpiodevice_release(struct device *dev)
 	list_del(&gdev->list);
 	spin_unlock_irqrestore(&gpio_lock, flags);
 
-	ida_free(&gpio_ida, gdev->id);
+	ida_simple_remove(&gpio_ida, gdev->id);
 	kfree_const(gdev->label);
 	kfree(gdev->descs);
 	kfree(gdev);
@@ -594,6 +594,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 	unsigned long flags;
 	int base = gc->base;
 	unsigned int i;
+	int alias_id, first_dynamic;
 	int ret = 0;
 	u32 ngpios;
 
@@ -623,11 +624,20 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 	 */
 	gdev->dev.fwnode = dev_fwnode(&gdev->dev) ?: fwnode;
 
-	gdev->id = ida_alloc(&gpio_ida, GFP_KERNEL);
-	if (gdev->id < 0) {
-		ret = gdev->id;
-		goto err_free_gdev;
+	alias_id = of_alias_get_id(gdev->dev.of_node, "gpio");
+	if (alias_id < 0) {
+		first_dynamic = of_alias_get_highest_id("gpio");
+		if (first_dynamic < 0)
+			first_dynamic = 0;
+		else
+			first_dynamic++;
+		alias_id = ida_simple_get(&gpio_ida, first_dynamic, 0, GFP_KERNEL);
+		if (alias_id < 0) {
+			ret = alias_id;
+			goto err_free_gdev;
+		}
 	}
+	gdev->id = alias_id;
 
 	ret = dev_set_name(&gdev->dev, GPIOCHIP_NAME "%d", gdev->id);
 	if (ret)
@@ -821,7 +831,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 err_free_dev_name:
 	kfree(dev_name(&gdev->dev));
 err_free_ida:
-	ida_free(&gpio_ida, gdev->id);
+	ida_simple_remove(&gpio_ida, gdev->id);
 err_free_gdev:
 	/* failures here can mean systems won't boot... */
 	if (ret != -EPROBE_DEFER) {
-- 
2.25.1