exynos/s5p: Add helper function for reading a single MVL3 GPIO

This adds a helper function to read only a single GPIO which uses
3-state logic. Examples of this typically include board straps which
are used to provide mainboard-specific information at the hardware-
level, such as board revision or configuration options.

This is part of a larger clean-up effort for Snow. We may want to
genericise this for other CPUs in the future.

Change-Id: Ic44f5e589cda89b419a07eca246847e9ce7dcd8d
Signed-off-by: David Hendricks <dhendrix@chromium.org>
Reviewed-on: http://review.coreboot.org/2266
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/cpu/samsung/exynos5250/gpio.h b/src/cpu/samsung/exynos5250/gpio.h
index 7606262062..12143849f5 100644
--- a/src/cpu/samsung/exynos5250/gpio.h
+++ b/src/cpu/samsung/exynos5250/gpio.h
@@ -477,6 +477,15 @@ void gpio_set_rate(int gpio, int mode);
  */
 int gpio_decode_number(unsigned gpio_list[], int count);
 
+/*
+ * similar to gpio_decode_number, but reads only a single GPIO
+ *
+ * @param gpio		GPIO to read
+ * @return -1 if the value cannot be determined. Otherwise returns
+ *              the corresponding MVL3 enum value.
+ */
+int gpio_read_mvl3(unsigned gpio);
+
 void gpio_info(void);
 
 #endif	/* EXYNOS5250_GPIO_H_ */