Add new GPIO subsystem.

This gpio subsystem keeps track of the GPIO pins which
have been reserved and takes care of the housekeeping
with keeping them running.

This gpio subsystem also knows which alternate functions
belong to which pins, so it can automatically configure
the pins for the alternate functions.

1 files changed, 14 insertions, 0 deletions

diff --git a/02-usart/src/kern/gpio/sysled.c b/02-usart/src/kern/gpio/sysled.c
new file mode 100644
index 0000000..a728da3
--- /dev/null
+++ b/02-usart/src/kern/gpio/sysled.c
@@ -0,0 +1,14 @@
+#include "kern/gpio/sysled.h"
+
+#define SYSLED GPIO_PIN_PB3
+
+gpio_reserved_pin_t get_sysled()
+{
+  if (gpio_pin_in_use(SYSLED)) {
+    return (gpio_reserved_pin_t) { .v_ = SYSLED };
+  }
+  
+  int ec;
+  gpio_pin_opts_t opts = DEFAULT_GPIO_OPTS_OUTPUT;
+  return reserve_gpio_pin(SYSLED, &opts, &ec);
+}