board/sg-led.c: Implement RGB LED support

Used by AiMe reader, possibly used elsewhere.

board/sg-led-cmd.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <stdint.h>
+
+#include "board/sg-cmd.h"
+
+enum {
+    SG_RGB_CMD_SET_COLOR            = 0x81,
+    SG_RGB_CMD_RESET                = 0xF5,
+    SG_RGB_CMD_GET_INFO             = 0xF0,
+};
+
+struct sg_led_resp_reset {
+    struct sg_resp_header resp;
+    uint8_t payload;
+};
+
+struct sg_led_resp_get_info {
+    struct sg_resp_header resp;
+    uint8_t payload[9];
+};
+
+struct sg_led_req_set_color {
+    struct sg_req_header req;
+    uint8_t payload[3];
+};
+
+union sg_led_req_any {
+    uint8_t bytes[256];
+    struct sg_req_header simple;
+    struct sg_led_req_set_color set_color;
+};
+
+union sg_led_resp_any {
+    uint8_t bytes[256];
+    struct sg_resp_header simple;
+    struct sg_led_resp_reset reset;
+    struct sg_led_resp_get_info get_info;
+};