gpio: Fix ngpio in gpio-xilinx driver

If one adds gpio-controller; to the chip in the devicetree, then
initialization fails with 'gpiochip_find_base: cannot find free range',
because ngpio is 0. This patch fixes the bug.

This version includes the suggestions from Linus Walleij.

Tested on ml507 board.

Signed-off-by: Gernot Vormayr <gvormayr@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 15 insertions, 12 deletions

diff --git a/drivers/gpio/gpio-xilinx.c b/drivers/gpio/gpio-xilinx.c
index 12481867daf1..ba18b06c9a21 100644
--- a/drivers/gpio/gpio-xilinx.c
+++ b/drivers/gpio/gpio-xilinx.c
@@ -197,6 +197,7 @@ static int xgpio_of_probe(struct device_node *np)
         struct xgpio_instance *chip;
         int status = 0;
         const u32 *tree_info;
+        u32 ngpio;
 
         chip = kzalloc(sizeof(*chip), GFP_KERNEL);
         if (!chip)
@@ -211,12 +212,13 @@ static int xgpio_of_probe(struct device_node *np)
         /* Update GPIO direction shadow register with default value */
         of_property_read_u32(np, "xlnx,tri-default", &chip->gpio_dir);
 
-        /* By default assume full GPIO controller */
-        chip->mmchip.gc.ngpio = 32;
-
-        /* Check device node and parent device node for device width */
-        of_property_read_u32(np, "xlnx,gpio-width",
-                              (u32 *)&chip->mmchip.gc.ngpio);
+        /*
+         * Check device node and parent device node for device width
+         * and assume default width of 32
+         */
+        if (of_property_read_u32(np, "xlnx,gpio-width", &ngpio))
+                ngpio = 32;
+        chip->mmchip.gc.ngpio = (u16)ngpio;
 
         spin_lock_init(&chip->gpio_lock);
 
@@ -258,12 +260,13 @@ static int xgpio_of_probe(struct device_node *np)
                 /* Update GPIO direction shadow register with default value */
                 of_property_read_u32(np, "xlnx,tri-default-2", &chip->gpio_dir);
 
-                /* By default assume full GPIO controller */
-                chip->mmchip.gc.ngpio = 32;
-
-                /* Check device node and parent device node for device width */
-                of_property_read_u32(np, "xlnx,gpio2-width",
-                                     (u32 *)&chip->mmchip.gc.ngpio);
+                /*
+                 * Check device node and parent device node for device width
+                 * and assume default width of 32
+                 */
+                if (of_property_read_u32(np, "xlnx,gpio2-width", &ngpio))
+                        ngpio = 32;
+                chip->mmchip.gc.ngpio = (u16)ngpio;
 
                 spin_lock_init(&chip->gpio_lock);