msm: trout: add gpio_to_irq

trout has gpiolib support and interrupt support, but was
missing the gpio_to_irq function. This adds that functions
which should allow proper translation.

Signed-off-by: Daniel Walker <dwalker@codeaurora.org>
Signed-off-by: David Brown <davidb@codeaurora.org>
diff --git a/arch/arm/mach-msm/board-trout-gpio.c b/arch/arm/mach-msm/board-trout-gpio.c
index c50f3af..f8c09ef 100644
--- a/arch/arm/mach-msm/board-trout-gpio.c
+++ b/arch/arm/mach-msm/board-trout-gpio.c
@@ -72,6 +72,13 @@
 	return 0;
 }
 
+static int trout_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
+{
+	struct msm_gpio_chip *msm_gpio = to_msm_gpio_chip(chip);
+
+	return TROUT_GPIO_TO_INT(offset + chip->base);
+}
+
 #define TROUT_GPIO_BANK(name, reg_num, base_gpio, shadow_val)		\
 	{								\
 		.chip = {						\
@@ -80,6 +87,7 @@
 			.direction_output = msm_gpiolib_direction_output, \
 			.get		  = msm_gpiolib_get,		\
 			.set		  = msm_gpiolib_set,		\
+			.to_irq		  = trout_gpio_to_irq,		\
 			.base		  = base_gpio,			\
 			.ngpio		  = 8,				\
 		},							\