nios2: add gpio_is_valid

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Signed-off-by: Scott McNutt <smcnutt@psyent.com>
diff --git a/board/altera/nios2-generic/custom_fpga.h b/board/altera/nios2-generic/custom_fpga.h
index a11add5..f7f3853 100644
--- a/board/altera/nios2-generic/custom_fpga.h
+++ b/board/altera/nios2-generic/custom_fpga.h
@@ -50,6 +50,7 @@
 
 /* led_pio.s1 is a altera_avalon_pio */
 #define LED_PIO_BASE 0x82120870
+#define LED_PIO_WIDTH 8
 
 /* high_res_timer.s1 is a altera_avalon_timer */
 #define CONFIG_SYS_TIMER_BASE 0x82120820
diff --git a/board/altera/nios2-generic/gpio.c b/board/altera/nios2-generic/gpio.c
index 8c639ce..4a30564 100644
--- a/board/altera/nios2-generic/gpio.c
+++ b/board/altera/nios2-generic/gpio.c
@@ -10,6 +10,7 @@
 #ifndef CONFIG_SYS_GPIO_BASE
 
 #define ALTERA_PIO_BASE LED_PIO_BASE
+#define ALTERA_PIO_WIDTH LED_PIO_WIDTH
 #define ALTERA_PIO_DATA (ALTERA_PIO_BASE + 0)
 #define ALTERA_PIO_DIR (ALTERA_PIO_BASE + 4)
 static u32 pio_data_reg;
@@ -62,4 +63,9 @@
 		pio_data_reg &= ~mask;
 	writel(pio_data_reg, ALTERA_PIO_DATA);
 }
+
+int gpio_is_valid(int number)
+{
+	return ((unsigned)number) < ALTERA_PIO_WIDTH;
+}
 #endif