esp8266: Implement basic C-level pin HAL.
diff --git a/esp8266/esp_mphal.h b/esp8266/esp_mphal.h
index 6713e42..ec2ed5b 100644
--- a/esp8266/esp_mphal.h
+++ b/esp8266/esp_mphal.h
@@ -56,4 +56,24 @@
 void ets_event_poll(void);
 #define ETS_POLL_WHILE(cond) { while (cond) ets_event_poll(); }
 
+// C-level pin HAL
+#include "etshal.h"
+#include "gpio.h"
+#include "esp8266/modpyb.h"
+#define mp_hal_pin_obj_t pyb_pin_obj_t
+#define mp_hal_get_pin_obj(o) mp_obj_get_pin_obj(o)
+#define mp_hal_pin_config_od(p) do { \
+        ETS_GPIO_INTR_DISABLE(); \
+        PIN_FUNC_SELECT((p)->periph, (p)->func); \
+        GPIO_REG_WRITE(GPIO_PIN_ADDR(GPIO_ID_PIN((p)->phys_port)), \
+            GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN((p)->phys_port))) \
+            | GPIO_PIN_PAD_DRIVER_SET(GPIO_PAD_DRIVER_ENABLE)); /* open drain */ \
+        GPIO_REG_WRITE(GPIO_ENABLE_ADDRESS, \
+            GPIO_REG_READ(GPIO_ENABLE_ADDRESS) | (1 << (p)->phys_port)); \
+        ETS_GPIO_INTR_ENABLE(); \
+    } while (0)
+#define mp_hal_pin_low(p) gpio_output_set(0, 1 << (p)->phys_port, 1 << (p)->phys_port, 0)
+#define mp_hal_pin_od_high(p) gpio_output_set(1 << (p)->phys_port, 0, 1 << (p)->phys_port, 0)
+#define mp_hal_pin_read(p) GPIO_INPUT_GET(GPIO_ID_PIN((p)->phys_port))
+
 #endif // _INCLUDED_MPHAL_H_