[PATCH 11/19] ArmPlatformPkg: Implement LcdIdentify function for HDLCD GOP

[evan.lloyd@arm.com]

From: Girish Pathak <girish.pathak@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/Include/Drivers/HdLcd.h              |  4 +++-
 ArmPlatformPkg/Drivers/LcdGraphicsOutputDxe/HdLcd.c | 22 +++++++++++++++++++-
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/ArmPlatformPkg/Include/Drivers/HdLcd.h b/ArmPlatformPkg/Include/Drivers/HdLcd.h
index 6df97a9dfee60e9fda615cf3bea1b6a164a42333..69b47cd720bae86081753affe2f3fafc8aa6c4d0 100644
--- a/ArmPlatformPkg/Include/Drivers/HdLcd.h
+++ b/ArmPlatformPkg/Include/Drivers/HdLcd.h
@@ -1,6 +1,6 @@
 /** @file  HDLcd.h
 
- Copyright (c) 2011-2012, ARM Ltd. All rights reserved.<BR>
+ Copyright (c) 2011-2017, ARM Ltd. All rights reserved.<BR>
 
  This program and the accompanying materials
  are licensed and made available under the terms and conditions of the BSD License
@@ -86,4 +86,6 @@
 // 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/Drivers/LcdGraphicsOutputDxe/HdLcd.c b/ArmPlatformPkg/Drivers/LcdGraphicsOutputDxe/HdLcd.c
index a266671a26f01d31e8ddb0cf7cbfe59d2f4dc49c..33c555e75cafaf9affddd0992c4bd9f9289f6703 100644
--- a/ArmPlatformPkg/Drivers/LcdGraphicsOutputDxe/HdLcd.c
+++ b/ArmPlatformPkg/Drivers/LcdGraphicsOutputDxe/HdLcd.c
@@ -159,6 +159,22 @@ LcdShutdown (
   MmioWrite32 (HDLCD_REG_COMMAND, HDLCD_DISABLE);
 }
 
+/** Get the HDLCD Product Id (from the version register).
+**/
+STATIC
+UINT32 GetHdlcdProductId(VOID)
+{
+  return ((MmioRead32 (HDLCD_REG_VERSION)) >> 16) ;
+}
+
+/** Check if an HDLCD is present.
+**/
+STATIC
+BOOLEAN HdlcdPresent(VOID)
+{
+  return (GetHdlcdProductId() == HDLCD_PRODUCT_ID);
+}
+
 /** Check for presence of HDLCD.
   *
   * @retval EFI_SUCCESS            Platform implements HDLCD.
@@ -170,5 +186,9 @@ LcdIdentify (
   VOID
   )
 {
-  return EFI_SUCCESS;
+  if (HdlcdPresent()) {
+    return EFI_SUCCESS;
+  }
+
+  return EFI_NOT_FOUND;
 }
-- 
Guid("CE165669-3EF3-493F-B85D-6190EE5B9759")