[PATCH v2 06/13] ArmPlatformPkg: Implement LcdIdentify function for HDLCD GOP

[evan.lloyd@arm.com]

From: Girish Pathak <girish.pathak at arm.com>

LcdIdentify function does not currently check presence of HDLCD
controller.

Implement this functionality by reading HDLCD_REG_VERSION and checking
against the PRODUCT_ID field to detect presence of HDLCD controller.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Girish Pathak <girish.pathak@arm.com>
Signed-off-by: Evan Lloyd <evan.lloyd@arm.com>
---
 ArmPlatformPkg/Library/HdLcd/HdLcd.h | 2 ++
 ArmPlatformPkg/Library/HdLcd/HdLcd.c | 8 +++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/ArmPlatformPkg/Library/HdLcd/HdLcd.h b/ArmPlatformPkg/Library/HdLcd/HdLcd.h
index 861d3c398f7d6b9a171b4d8718c2816419d8e20a..b69fc3436a190b7b20df63fac42e4bef2b522942 100644
--- a/ArmPlatformPkg/Library/HdLcd/HdLcd.h
+++ b/ArmPlatformPkg/Library/HdLcd/HdLcd.h
@@ -85,4 +85,6 @@
 // Number of bytes per pixel
 #define HDLCD_4BYTES_PER_PIXEL           ((4 - 1) << 3)
 
+#define HDLCD_PRODUCT_ID                 0x1CDC
+
 #endif /* HDLCD_H_ */
diff --git a/ArmPlatformPkg/Library/HdLcd/HdLcd.c b/ArmPlatformPkg/Library/HdLcd/HdLcd.c
index d71b6020dc0c4b91e74d16e96b06a60601b9628a..b2779af041fae58d712270002cc7d6d277360311 100644
--- a/ArmPlatformPkg/Library/HdLcd/HdLcd.c
+++ b/ArmPlatformPkg/Library/HdLcd/HdLcd.c
@@ -174,9 +174,15 @@ LcdShutdown (VOID)
 
   @retval EFI_SUCCESS            Returns success if platform implements a HDLCD
                                  controller.
+  @retval EFI_NOT_FOUND          HDLCD display controller not found on the
+                                 platform.
 **/
 EFI_STATUS
 LcdIdentify (VOID)
 {
-  return EFI_SUCCESS;
+  if ((MmioRead32 (HDLCD_REG_VERSION) >> 16) == HDLCD_PRODUCT_ID) {
+    return EFI_SUCCESS;
+  }
+
+  return EFI_NOT_FOUND;
 }
-- 
Guid("CE165669-3EF3-493F-B85D-6190EE5B9759")