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

Used by AiMe reader, possibly used elsewhere.

board/sg-led.h

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <windows.h>
+
+#include <stdint.h>
+
+#include "hook/iobuf.h"
+
+struct sg_led_ops {
+    HRESULT (*reset)(void *ctx);
+    HRESULT (*set_color)(void *ctx, uint8_t r, uint8_t g, uint8_t b);
+};
+
+struct sg_led {
+    const struct sg_led_ops *ops;
+    void *ops_ctx;
+    uint8_t addr;
+};
+
+void sg_led_init(
+        struct sg_led *led,
+        uint8_t addr,
+        const struct sg_led_ops *ops,
+        void *ctx);
+
+void sg_led_transact(
+        struct sg_led *led,
+        struct iobuf *resp_frame,
+        const void *req_bytes,
+        size_t req_nbytes);