Input: gpio_keys - allow separating gpio and irq in device tree

This change allows specify interrupt for buttons separately form gpio,
potentially allowing to form several "clusters" of buttons on
different interrupts.

Button defined without both gpio and irq in device tree is a hared error
instead of a warning now.

Tested-by: Andy Shevchenko <[e-mail]>
Reviewed-by: Linus Walleij <[e-mail]>
Signed-off-by: Dmitry Torokhov <[e-mail]>

Documentation/devicetree/bindings/input/gpio-keys.txt

···
 Each button (key) is represented as a sub-node of "gpio-keys":
 Subnode properties:
 
+	- gpios: OF device-tree gpio specification.
+	- interrupts: the interrupt line for that input.
 	- label: Descriptive name of the key.
 	- linux,code: Keycode to emit.
 
-Required mutual exclusive subnode-properties:
-	- gpios: OF device-tree gpio specification.
-	- interrupts: the interrupt line for that input
+Note that either "interrupts" or "gpios" properties can be omitted, but not
+both at the same time. Specifying both properties is allowed.
 
 Optional subnode-properties:
 	- linux,input-type: Specify event type this button/key generates.
···
 	- debounce-interval: Debouncing interval time in milliseconds.
 	  If not specified defaults to 5.
 	- gpio-key,wakeup: Boolean, button can wake-up the system.
+	- linux,can-disable: Boolean, indicates that button is connected
+	  to dedicated (not shared) interrupt which can be disabled to
+	  suppress events from the button.
 
 Example nodes:
 

drivers/input/keyboard/gpio_keys.c

···
 						button->debounce_interval;
 		}
 
-		irq = gpio_to_irq(button->gpio);
-		if (irq < 0) {
-			error = irq;
-			dev_err(dev,
-				"Unable to get irq number for GPIO %d, error %d\n",
-				button->gpio, error);
-			return error;
+		if (button->irq) {
+			bdata->irq = button->irq;
+		} else {
+			irq = gpio_to_irq(button->gpio);
+			if (irq < 0) {
+				error = irq;
+				dev_err(dev,
+					"Unable to get irq number for GPIO %d, error %d\n",
+					button->gpio, error);
+				return error;
+			}
+			bdata->irq = irq;
 		}
-		bdata->irq = irq;
 
 		INIT_WORK(&bdata->work, gpio_keys_gpio_work_func);
 		setup_timer(&bdata->timer,
···
 
 	i = 0;
 	for_each_child_of_node(node, pp) {
-		int gpio = -1;
 		enum of_gpio_flags flags;
 
 		button = &pdata->buttons[i++];
 
-		if (!of_find_property(pp, "gpios", NULL)) {
-			button->irq = irq_of_parse_and_map(pp, 0);
-			if (button->irq == 0) {
-				i--;
-				pdata->nbuttons--;
-				dev_warn(dev, "Found button without gpios or irqs\n");
-				continue;
-			}
-		} else {
-			gpio = of_get_gpio_flags(pp, 0, &flags);
-			if (gpio < 0) {
-				error = gpio;
+		button->gpio = of_get_gpio_flags(pp, 0, &flags);
+		if (button->gpio < 0) {
+			error = button->gpio;
+			if (error != -ENOENT) {
 				if (error != -EPROBE_DEFER)
 					dev_err(dev,
 						"Failed to get gpio flags, error: %d\n",
 						error);
 				return ERR_PTR(error);
 			}
+		} else {
+			button->active_low = flags & OF_GPIO_ACTIVE_LOW;
 		}
 
-		button->gpio = gpio;
-		button->active_low = flags & OF_GPIO_ACTIVE_LOW;
+		button->irq = irq_of_parse_and_map(pp, 0);
+
+		if (!gpio_is_valid(button->gpio) && !button->irq) {
+			dev_err(dev, "Found button without gpios or irqs\n");
+			return ERR_PTR(-EINVAL);
+		}
 
 		if (of_property_read_u32(pp, "linux,code", &button->code)) {
 			dev_err(dev, "Button without keycode: 0x%x\n",
···
 			button->type = EV_KEY;
 
 		button->wakeup = !!of_get_property(pp, "gpio-key,wakeup", NULL);
+
+		button->can_disable = !!of_get_property(pp, "linux,can-disable", NULL);
 
 		if (of_property_read_u32(pp, "debounce-interval",
 					 &button->debounce_interval))