feat(lv_port): Add abstraction for busy signal

This signal can be used when driving eink displays

lv_port/lv_port_display_espressif.c

@@ -39,3 +39,19 @@ void display_port_gpio_rst(lv_disp_drv_t *drv, uint8_t state)
     gpio_set_level(CONFIG_LV_DISP_PIN_RST, state);
 #endif
 }
+
+display_port_busy_t display_port_gpio_is_busy(lv_disp_drv_t *drv)
+{
+    (void) drv;
+
+    display_port_busy_t device_busy = DISPLAY_PORT_DEVICE_NOT_BUSY;
+
+#ifdef CONFIG_LV_DISP_PIN_BUSY
+    /* FIXME Assuming the busy signal in logic 1 means the device is busy */
+    if (gpio_get_level(CONFIG_LV_DISP_PIN_BUSY) == 1) {
+        device_busy = DISPLAY_PORT_DEVICE_IS_BUSY;
+    }
+#endif
+
+    return device_busy;
+}

lvgl_tft/display_port.h

@@ -12,6 +12,14 @@ extern "C"
 #include "lvgl/lvgl.h"
 #endif
 
+/** Display is busy port
+ * Useful for eink displays that need to poll their BUSY signal */
+typedef enum {
+    DISPLAY_PORT_DEVICE_NOT_BUSY,
+    DISPLAY_PORT_DEVICE_IS_BUSY,
+    /* NOTE Operation should not be interrupted when the device is busy */
+} display_port_busy_t;
+
 /**
  * Busy wait delay port
  *
@@ -44,6 +52,16 @@ void display_port_gpio_dc(lv_disp_drv_t *drv, uint8_t state);
  */
 void display_port_gpio_rst(lv_disp_drv_t *drv, uint8_t state);
 
+/**
+ * Display is busy port
+ *
+ * @param drv Pointer to driver See @ref lv_disp_drv_t
+ *
+ * @retval Returns DISPLAY_PORT_DEVICE_NOT_BUSY when display is not busy,
+ * DISPLAY_PORT_DEVICE_IS_BUSY otherwise.
+ */
+display_port_busy_t display_port_gpio_is_busy(lv_disp_drv_t *drv);
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif