lynxpoint: provide gpio_is_native()

There's a need to determine if a specific gpio pin is
is set up to be a native function or not. Implement this.

Change-Id: I91d57a549e0f4fddc0b1849e5f74320fc839642c
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/59589
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/4324
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/southbridge/intel/lynxpoint/gpio.c

@@ -128,3 +128,22 @@ void set_gpio(int gpio_num, int value)
 	config |= value << bit;
 	outl(config, gpio_base + gpio_reg_offsets[index]);
 }
+
+int gpio_is_native(int gpio_num)
+{
+	static const int gpio_reg_offsets[] = {
+		GPIO_USE_SEL, GPIO_USE_SEL2, GPIO_USE_SEL3
+	};
+	u16 gpio_base = get_gpio_base();
+	int index, bit;
+	u32 config;
+
+	if (gpio_num > MAX_GPIO_NUMBER)
+		return 0; /* Just ignore wrong gpio numbers. */
+
+	index = gpio_num / 32;
+	bit = gpio_num % 32;
+
+	config = inl(gpio_base + gpio_reg_offsets[index]);
+	return !(config & (1 << bit));
+}

src/southbridge/intel/lynxpoint/lp_gpio.c

@@ -159,3 +159,10 @@ void set_gpio(int gpio_num, int value)
 	conf0 |= value << GPO_LEVEL_SHIFT;
 	outl(conf0, gpio_base + GPIO_CONFIG0(gpio_num));
 }
+
+int gpio_is_native(int gpio_num)
+{
+	u16 gpio_base = get_gpio_base();
+
+	return !(inl(gpio_base + GPIO_CONFIG0(gpio_num)) & 1);
+}

src/southbridge/intel/lynxpoint/pch.h

@@ -201,6 +201,8 @@ unsigned get_gpios(const int *gpio_num_array);
  * set GPIO pin value
  */
 void set_gpio(int gpio_num, int value);
+/* Return non-zero if gpio is set to native function. 0 otherwise. */
+int gpio_is_native(int gpio_num);
 #endif
 
 #define MAINBOARD_POWER_OFF	0