gpio: of: Add support for multiple GPIOs in a single GPIO hog

When listing multiple GPIOs in the "gpios" property of a GPIO hog, only
the first GPIO is affected.  The user is left clueless about the
dysfunctioning of the other GPIOs specified.

Fix this by adding and documenting support for specifying multiple
GPIOs in a single GPIO hog.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib-of.c

@@ -160,6 +160,7 @@ struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id,
  * of_parse_own_gpio() - Get a GPIO hog descriptor, names and flags for GPIO API
  * @np:		device node to get GPIO from
  * @chip:	GPIO chip whose hog is parsed
+ * @idx:	Index of the GPIO to parse
  * @name:	GPIO line name
  * @lflags:	gpio_lookup_flags - returned from of_find_gpio() or
  *		of_parse_own_gpio()
@@ -170,7 +171,7 @@ struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id,
  */
 static struct gpio_desc *of_parse_own_gpio(struct device_node *np,
 					   struct gpio_chip *chip,
-					   const char **name,
+					   unsigned int idx, const char **name,
 					   enum gpio_lookup_flags *lflags,
 					   enum gpiod_flags *dflags)
 {
@@ -178,6 +179,7 @@ static struct gpio_desc *of_parse_own_gpio(struct device_node *np,
 	enum of_gpio_flags xlate_flags;
 	struct of_phandle_args gpiospec;
 	struct gpio_desc *desc;
+	unsigned int i;
 	u32 tmp;
 	int ret;
 
@@ -196,9 +198,12 @@ static struct gpio_desc *of_parse_own_gpio(struct device_node *np,
 	gpiospec.np = chip_np;
 	gpiospec.args_count = tmp;
 
-	ret = of_property_read_u32_array(np, "gpios", gpiospec.args, tmp);
-	if (ret)
-		return ERR_PTR(ret);
+	for (i = 0; i < tmp; i++) {
+		ret = of_property_read_u32_index(np, "gpios", idx * tmp + i,
+						 &gpiospec.args[i]);
+		if (ret)
+			return ERR_PTR(ret);
+	}
 
 	desc = of_xlate_and_get_gpiod_flags(chip, &gpiospec, &xlate_flags);
 	if (IS_ERR(desc))
@@ -240,20 +245,24 @@ static int of_gpiochip_scan_gpios(struct gpio_chip *chip)
 	const char *name;
 	enum gpio_lookup_flags lflags;
 	enum gpiod_flags dflags;
+	unsigned int i;
 	int ret;
 
 	for_each_available_child_of_node(chip->of_node, np) {
 		if (!of_property_read_bool(np, "gpio-hog"))
 			continue;
 
-		desc = of_parse_own_gpio(np, chip, &name, &lflags, &dflags);
-		if (IS_ERR(desc))
-			continue;
+		for (i = 0;; i++) {
+			desc = of_parse_own_gpio(np, chip, i, &name, &lflags,
+						 &dflags);
+			if (IS_ERR(desc))
+				break;
 
-		ret = gpiod_hog(desc, name, lflags, dflags);
-		if (ret < 0) {
-			of_node_put(np);
-			return ret;
+			ret = gpiod_hog(desc, name, lflags, dflags);
+			if (ret < 0) {
+				of_node_put(np);
+				return ret;
+			}
 		}
 	}