Implement some services from gsp::Lcd.

https://www.3dbrew.org/wiki/GSP_Services

libctru/include/3ds/services/gsp.h

@@ -51,6 +51,9 @@ typedef enum
 Result gspInit();
 void gspExit();
 
+Result gspLcdInit();
+void gspLcdExit();
+
 Result gspInitEventHandler(Handle gspEvent, vu8* gspSharedMem, u8 gspThreadId);
 void gspExitEventHandler();
 void gspWaitForEvent(GSP_Event id, bool nextEvent);
@@ -79,3 +82,7 @@ Result GSPGPU_RegisterInterruptRelayQueue(Handle *handle, Handle eventHandle, u3
 Result GSPGPU_UnregisterInterruptRelayQueue(Handle* handle);
 Result GSPGPU_TriggerCmdReqQueue(Handle *handle);
 Result GSPGPU_SubmitGxCommand(u32* sharedGspCmdBuf, u32 gxCommand[0x8], Handle* handle);
+
+// 1 = top, 2 = bottom, 3 = both
+Result GSPLCD_PowerOffBacklight(u32 screen);
+Result GSPLCD_PowerOnBacklight(u32 screen);

libctru/source/services/gsp.c

@@ -12,6 +12,7 @@
 #define GSP_EVENT_STACK_SIZE 0x1000
 
 Handle gspGpuHandle=0;
+Handle gspLcdHandle=0;
 Handle gspEvents[GSPEVENT_MAX];
 vu32 gspEventCounts[GSPEVENT_MAX];
 u64 gspEventStack[GSP_EVENT_STACK_SIZE/sizeof(u64)]; //u64 so that it's 8-byte aligned
@@ -431,3 +432,37 @@ Result GSPGPU_SubmitGxCommand(u32* sharedGspCmdBuf, u32 gxCommand[0x8], Handle*
  if(totalCommands==1)return GSPGPU_TriggerCmdReqQueue(handle);
  return 0;
 }
+
+Result gspLcdInit()
+{
+ return srvGetServiceHandle(&gspLcdHandle, "gsp::Lcd");
+}
+
+void gspLcdExit()
+{
+ if(gspLcdHandle)svcCloseHandle(gspLcdHandle);
+}
+
+Result GSPLCD_PowerOffBacklight(u32 screen)
+{
+ u32 *cmdbuf = getThreadCommandBuffer();
+
+ cmdbuf[0] = 0x00120040;
+ cmdbuf[1] = screen;
+
+ Result ret = svcSendSyncRequest(gspLcdHandle);
+
+ return ret;
+}
+
+Result GSPLCD_PowerOnBacklight(u32 screen)
+{
+ u32 *cmdbuf = getThreadCommandBuffer();
+
+ cmdbuf[0] = 0x00110040;
+ cmdbuf[1] = screen;
+
+ Result ret = svcSendSyncRequest(gspLcdHandle);
+
+ return ret;
+}