soc/intel/apollolake: Add function to translate gpio_t into ACPI pin

There are four GPIO communities in this SOC and they are implemented
as separate ACPI devices.  This means the pin number that is used in
an ACPI GPIO declaration needs to be relative to the community that
the pin resides in.  Also select GENERIC_GPIO_LIB in the SOC Kconfig
so this function actually gets used.

This was tested on the reef mainboard by verifying the output of the
SSDT for the Maxim 98357A codec that the assigned GPIO_76 is listed
as pin 0x24 which is the value relative to the Northwest community.

Change-Id: Iad2ab8eccf4c91185a075ffce8d41c81f06c1113
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://review.coreboot.org/15513
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins)

src/soc/intel/apollolake/Kconfig

@@ -24,6 +24,7 @@ config CPU_SPECIFIC_OPTIONS
 	select C_ENVIRONMENT_BOOTBLOCK
 	select COLLECT_TIMESTAMPS
 	select COMMON_FADT
+	select GENERIC_GPIO_LIB
 	select HAVE_INTEL_FIRMWARE
 	select HAVE_SMI_HANDLER
 	select MMCONF_SUPPORT

src/soc/intel/apollolake/gpio.c

@@ -132,3 +132,21 @@ const char *gpio_acpi_path(gpio_t gpio_num)
 
 	return NULL;
 }
+
+uint16_t gpio_acpi_pin(gpio_t gpio_num)
+{
+	const struct pad_community *comm = gpio_get_community(gpio_num);
+
+	switch (comm->port) {
+	case GPIO_NORTH:
+		return PAD_N(gpio_num);
+	case GPIO_NORTHWEST:
+		return PAD_NW(gpio_num);
+	case GPIO_WEST:
+		return PAD_W(gpio_num);
+	case GPIO_SOUTHWEST:
+		return PAD_SW(gpio_num);
+	}
+
+	return gpio_num;
+}