1 files changed, 128 insertions, 0 deletions
diff --git a/system-clock/include/gpio.h b/system-clock/include/gpio.h
new file mode 100644
index 0000000..53ece32
--- /dev/null
+++ b/system-clock/include/gpio.h
@@ -0,0 +1,128 @@
+#ifndef GPIO_H__
+#define GPIO_H__
+
+#include "common.h"
+
+#include <stdint.h>
+
+/*
+ * Possible GPIO ports.
+ */
+typedef enum {
+  GPIO_PORT_A = 0,
+  GPIO_PORT_B = 1,
+  GPIO_PORT_C = 2,
+  GPIO_PORT_D = 3
+} gpio_port_number_t;
+
+/*
+ * Structure defining the layout of the layout of the GPIO registers on the
+ * stm32l432 development board.
+ */
+typedef struct GPIO_PORT_STR {
+  __IO uint32_t mode_r;   /* Mode register */
+  __IO uint32_t pupd_r;   /* Pull up/pull down/none register */
+  __IO uint32_t speed_r;  /* Speed register */
+  __IO uint32_t type_r;   /* Type register */
+  __IO uint32_t input_r;  /* Input data register */
+  __IO uint32_t output_r; /* Output data register */
+  __IO uint32_t bsr_r;    /* Bit set/reset register */
+  __IO uint32_t lock_r;   /* Lock register */
+  __IO uint32_t altfn_r;  /* Alternate function register */
+} PACKED gpio_port_t;
+
+/*
+ * Enum defining the PINs in a GPIO port. Each port has 16 pins to use in
+ * the stm32l432.
+ */
+typedef enum GPIO_PIN_ENUM {
+  PIN_0  = 0,
+  PIN_1  = 1,
+  PIN_2  = 2,
+  PIN_3  = 3,
+  PIN_4  = 4,
+  PIN_5  = 5,
+  PIN_6  = 6,
+  PIN_7  = 7,
+  PIN_8  = 8,
+  PIN_9  = 9,
+  PIN_10 = 10,
+  PIN_11 = 11,
+  PIN_12 = 12,
+  PIN_13 = 13,
+  PIN_14 = 14,
+  PIN_15 = 15
+} gpio_pin_t;
+
+/*
+ * Enum defining the pin modes that are possible.
+ */
+typedef enum {
+  MODE_INPUT     = 0,
+  MODE_OUTPUT    = 1,
+  MODE_ALTERNATE = 2,
+  MODE_ANALOG    = 3
+} gpio_pin_mode_t;
+
+/*
+ * Enum defining the pin speeds that are possible.
+ */
+typedef enum {
+  SPEED_2MHZ = 0,
+  SPEED_10MHZ = 1,
+  SPEED_50MHZ = 3,
+} speed_t;
+
+/*
+ * Structure defining an OUTPUT pin. Structurally equivalent to the input pin,
+ * but can be used in a slightly type-safe manner.
+ */
+typedef struct {
+  __IO gpio_port_t* gpio_port;
+  gpio_pin_t pin;
+} gpio_output_pin_t;
+
+/*
+ * Sets the mode on a GPIO pin.
+ *
+ * gpio_port: the gpio port to use.
+ * pin: the pin number to set.
+ * pin_mode: the mode to set the pin to.
+ */
+void set_gpio_pin_mode(
+    __IO gpio_port_t* gpio_port,
+    gpio_pin_t pin,
+    gpio_pin_mode_t pin_mode);
+
+/*
+ * Sets the given GPIO pin to be an output pin. Returns an output_pin struct
+ * corresponding to
+ */
+gpio_output_pin_t set_gpio_pin_output(
+    __IO gpio_port_t* gpio_port,
+    gpio_pin_t pin);
+
+/*
+ * Sets an output pin on or off.
+ *
+ * pin: the pin to toggle.
+ * onoff: 0 for off, non-zero of on.
+ */
+void set_gpio_output_pin(
+    gpio_output_pin_t pin,
+    bool onoff);
+
+#define pin_on(p) \
+  set_gpio_output_pin(p, 1)
+
+#define pin_off(p) \
+  set_gpio_output_pin(p, 0)
+
+/*
+ * Enables a GPIO port and returns a reference to the register definition
+ * of that GPIO port.
+ */
+__IO gpio_port_t* enable_gpio(gpio_port_number_t number);
+
+
+#endif /* GPIO_H__ */