gpio: Adjust of_xlate API to support multiple GPIO chips

This patch changes the of_xlate API to make it possible for multiple
gpio_chips to refer to the same device tree node.  This is useful for
banked GPIO controllers that use multiple gpio_chips for a single
device.  With this change the core code will try calling of_xlate on
each gpio_chip that references the device_node and will return the
gpio number for the first one to return 'true'.
Tested-by: Roland Stigge <stigge@antcom.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

arch/arm/mach-imx/mach-mx35_3ds.c

@@ -96,8 +96,7 @@ static struct i2c_board_info __initdata i2c_devices_3ds[] = {
 
 static int lcd_power_gpio = -ENXIO;
 
-static int mc9s08dz60_gpiochip_match(struct gpio_chip *chip,
-						     const void *data)
+static int mc9s08dz60_gpiochip_match(struct gpio_chip *chip, void *data)
 {
 	return !strcmp(chip->label, data);
 }

drivers/gpio/gpiolib-of.c

@@ -15,11 +15,39 @@
 #include <linux/errno.h>
 #include <linux/module.h>
 #include <linux/io.h>
+#include <linux/gpio.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/of_gpio.h>
 #include <linux/slab.h>
 
+/* Private data structure for of_gpiochip_is_match */
+struct gg_data {
+	enum of_gpio_flags *flags;
+	struct of_phandle_args gpiospec;
+
+	int out_gpio;
+};
+
+/* Private function for resolving node pointer to gpio_chip */
+static int of_gpiochip_find_and_xlate(struct gpio_chip *gc, void *data)
+{
+	struct gg_data *gg_data = data;
+	int ret;
+
+	if ((gc->of_node != gg_data->gpiospec.np) ||
+	    (gc->of_gpio_n_cells != gg_data->gpiospec.args_count) ||
+	    (!gc->of_xlate))
+		return false;
+
+	ret = gc->of_xlate(gc, &gg_data->gpiospec, gg_data->flags);
+	if (ret < 0)
+		return false;
+
+	gg_data->out_gpio = ret + gc->base;
+	return true;
+}
+
 /**
  * of_get_named_gpio_flags() - Get a GPIO number and flags to use with GPIO API
  * @np:		device node to get GPIO from
@@ -34,46 +62,25 @@
 int of_get_named_gpio_flags(struct device_node *np, const char *propname,
                            int index, enum of_gpio_flags *flags)
 {
+	struct gg_data gg_data = { .flags = flags, .out_gpio = -ENODEV };
 	int ret;
-	struct gpio_chip *gc;
-	struct of_phandle_args gpiospec;
+
+	/* .of_xlate might decide to not fill in the flags, so clear it. */
+	if (flags)
+		*flags = 0;
 
 	ret = of_parse_phandle_with_args(np, propname, "#gpio-cells", index,
-					 &gpiospec);
+					 &gg_data.gpiospec);
 	if (ret) {
 		pr_debug("%s: can't parse gpios property\n", __func__);
-		goto err0;
-	}
-
-	gc = of_node_to_gpiochip(gpiospec.np);
-	if (!gc) {
-		pr_debug("%s: gpio controller %s isn't registered\n",
-			 np->full_name, gpiospec.np->full_name);
-		ret = -ENODEV;
-		goto err1;
-	}
-
-	if (gpiospec.args_count != gc->of_gpio_n_cells) {
-		pr_debug("%s: wrong #gpio-cells for %s\n",
-			 np->full_name, gpiospec.np->full_name);
-		ret = -EINVAL;
-		goto err1;
+		return -EINVAL;
 	}
 
-	/* .xlate might decide to not fill in the flags, so clear it. */
-	if (flags)
-		*flags = 0;
-
-	ret = gc->of_xlate(gc, &gpiospec, flags);
-	if (ret < 0)
-		goto err1;
+	gpiochip_find(&gg_data, of_gpiochip_find_and_xlate);
 
-	ret += gc->base;
-err1:
-	of_node_put(gpiospec.np);
-err0:
+	of_node_put(gg_data.gpiospec.np);
 	pr_debug("%s exited with status %d\n", __func__, ret);
-	return ret;
+	return gg_data.out_gpio;
 }
 EXPORT_SYMBOL(of_get_named_gpio_flags);
 
@@ -227,14 +234,3 @@ void of_gpiochip_remove(struct gpio_chip *chip)
 	if (chip->of_node)
 		of_node_put(chip->of_node);
 }
-
-/* Private function for resolving node pointer to gpio_chip */
-static int of_gpiochip_is_match(struct gpio_chip *chip, const void *data)
-{
-	return chip->of_node == data;
-}
-
-struct gpio_chip *of_node_to_gpiochip(struct device_node *np)
-{
-	return gpiochip_find(np, of_gpiochip_is_match);
-}

drivers/gpio/gpiolib.c

@@ -1156,7 +1156,7 @@ EXPORT_SYMBOL_GPL(gpiochip_remove);
  */
 struct gpio_chip *gpiochip_find(const void *data,
 				int (*match)(struct gpio_chip *chip,
-					     const void *data))
+					     void *data))
 {
 	struct gpio_chip *chip = NULL;
 	unsigned long flags;

include/asm-generic/gpio.h

@@ -144,7 +144,7 @@ extern int gpiochip_add(struct gpio_chip *chip);
 extern int __must_check gpiochip_remove(struct gpio_chip *chip);
 extern struct gpio_chip *gpiochip_find(const void *data,
 					int (*match)(struct gpio_chip *chip,
-						     const void *data));
+						     void *data));
 
 
 /* Always use the library code for GPIO management calls,

include/linux/of_gpio.h

@@ -58,7 +58,6 @@ extern int of_mm_gpiochip_add(struct device_node *np,
 
 extern void of_gpiochip_add(struct gpio_chip *gc);
 extern void of_gpiochip_remove(struct gpio_chip *gc);
-extern struct gpio_chip *of_node_to_gpiochip(struct device_node *np);
 extern int of_gpio_simple_xlate(struct gpio_chip *gc,
 				const struct of_phandle_args *gpiospec,
 				u32 *flags);