GPIO: Move definition of alternate functions to gpio.inc

This is a straightforward conversion of existing tables
into X-Macro style definitions for the GPIO alternate
functions.  This change in itself, is not particularly
powerful, but having all GPIO settings in a single file
makes a board easier to understand.

Signed-off-by: Anton Staaf <robotboy@chromium.org>

BRANCH=none
TEST=make buildall -j
     Followed by manual testing of interrupt on change and UART
     functionality on STM32F0 based discovery board.

Change-Id: Ib7f1f014f4bd289d7c0ac3100470ba2dc71ca579
Reviewed-on: https://chromium-review.googlesource.com/207987
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Tested-by: Anton Staaf <robotboy@chromium.org>
Commit-Queue: Anton Staaf <robotboy@chromium.org>

2 files changed, 32 insertions, 1 deletions

diff --git a/include/gpio.wrap b/include/gpio.wrap
index 941d97ac67..cf4fbb319a 100644
--- a/include/gpio.wrap
+++ b/include/gpio.wrap
@@ -16,7 +16,24 @@
  * parameters are passed on to the gpio_info directly.
  */
 #ifndef GPIO
-#define GPIO(name, port, pin, function, signal)
+#define GPIO(name, port, pin, flags, signal)
+#endif
+
+/*
+ * The ALTERNATE macro is used associate a GPIO with an alternate function.
+ *
+ * Alternate functions allow hardware peripherals access to GPIO pins.
+ * Modules use gpio_config_module to enable and disable the alternate functions
+ * of GPIOs assigned to that module.  So if the module parameter is MODULE_UART
+ * then when the uart_init function is called the GPIO will be switched to its
+ * alternate function mode.  The function parameter is chip/variant specific
+ * and will usually need to be looked up in the datasheet.  The flags parameter
+ * has the same meaning as in the GPIO macro above.  This macro can assign
+ * multiple pins on the same port to a module, the second parameter is the
+ * bitmask of pins to be assigned.
+ */
+#ifndef ALTERNATE
+#define ALTERNATE(port, mask, function, module, flags)
 #endif
 
 /*
@@ -44,4 +61,5 @@
  * Once the gpio.inc file has been included these macros are no longer needed.
  */
 #undef GPIO
+#undef ALTERNATE
 #undef UNIMPLEMENTED
diff --git a/include/gpio_list.h b/include/gpio_list.h
index 6d41fb9115..9077c17fd2 100644
--- a/include/gpio_list.h
+++ b/include/gpio_list.h
@@ -15,3 +15,16 @@ const struct gpio_info gpio_list[] = {
 };
 
 BUILD_ASSERT(ARRAY_SIZE(gpio_list) == GPIO_COUNT);
+
+/*
+ * Construct the gpio_alt_funcs array.  This array is used by gpio_config_module
+ * to enable and disable GPIO alternate functions on a module by module basis.
+ */
+#define ALTERNATE(port, mask, function, module, flags)	\
+	{GPIO_##port, mask, function, module, flags},
+
+const struct gpio_alt_func gpio_alt_funcs[] = {
+	#include "gpio.wrap"
+};
+
+const int gpio_alt_funcs_count = ARRAY_SIZE(gpio_alt_funcs);