[RFC PATCH 1/2] MdeModulePkg: introduce SD/MMC override protocol

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

Many ARM based SoCs have integrated SDHCI controllers, and often,
these implementations deviate in subtle ways from the pertinent
specifications. On the one hand, these deviations are quite easy
to work around, but on the other hand, having a collection of SoC
specific workarounds in the generic driver stack is undesirable.

So let's introduce an optional SD/MMC override protocol that we
can invoke at the appropriate moments in the device initialization.
That way, the workaround itself remains platform specific, but we
can still use the generic driver stack on such platforms.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 MdeModulePkg/Include/Protocol/SdMmcOverride.h | 95 ++++++++++++++++++++
 MdeModulePkg/MdeModulePkg.dec                 |  3 +
 2 files changed, 98 insertions(+)

diff --git a/MdeModulePkg/Include/Protocol/SdMmcOverride.h b/MdeModulePkg/Include/Protocol/SdMmcOverride.h
new file mode 100644
index 000000000000..95fc48bb8dee
--- /dev/null
+++ b/MdeModulePkg/Include/Protocol/SdMmcOverride.h
@@ -0,0 +1,95 @@
+/** @file
+  Protocol to describe overrides required to support non-standard SDHCI
+  implementations
+
+  Copyright (c) 2017, Linaro, 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
+  which accompanies this distribution.  The full text of the license may be found at
+  http://opensource.org/licenses/bsd-license.php
+
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+**/
+
+#ifndef __SD_MMC_OVERRIDE_H__
+#define __SD_MMC_OVERRIDE_H__
+
+#define EDKII_SD_MMC_OVERRIDE_PROTOCOL_GUID \
+  { 0xeaf9e3c1, 0xc9cd, 0x46db, { 0xa5, 0xe5, 0x5a, 0x12, 0x4c, 0x83, 0x23, 0x23 } }
+
+#define EDKII_SD_MMC_OVERRIDE_PROTOCOL_VERSION    0x1
+
+typedef struct _SD_MMC_OVERRIDE SD_MMC_OVERRIDE;
+
+typedef enum {
+  SD_MMC_OVERRIDE_RESET_PRE_HOOK,
+  SD_MMC_OVERRIDE_RESET_POST_HOOK,
+  SD_MMC_OVERRIDE_INIT_HOST_PRE_HOOK,
+  SD_MMC_OVERRIDE_INIT_HOST_POST_HOOK,
+} SD_MMC_OVERRIDE_HOOK;
+
+/**
+
+  Override function for SDHCI capability bits
+
+  @param[in]      ControllerHandle          The EFI_HANDLE of the controller.
+  @param[in]      Slot                      The 0 based slot index.
+  @param[in,out]  SdMmcHcSlotCapability     The SDHCI capability structure.
+
+  @retval EFI_SUCCESS           The override function completed successfully.
+  @retval EFI_NOT_FOUND         The specified controller or slot does not exist.
+  @retval EFI_INVALID_PARAMETER SdMmcHcSlotCapability is NULL
+
+**/
+typedef
+EFI_STATUS
+(EFIAPI * SD_MMC_OVERRIDE_CAPABILITY) (
+  IN      EFI_HANDLE              ControllerHandle,
+  IN      UINT8                   Slot,
+  IN  OUT VOID                    *SdMmcHcSlotCapability
+  );
+
+/**
+
+  Override function for SDHCI controller operations
+
+  @param[in]      ControllerHandle    The EFI_HANDLE of the controller.
+  @param[in]      Slot                The 0 based slot index.
+  @param[in,out]  HookType            The type of operation and whether the
+                                      hook is invoked right before (pre) or
+                                      right after (post)
+
+  @retval EFI_SUCCESS           The override function completed successfully.
+  @retval EFI_NOT_FOUND         The specified controller or slot does not exist.
+  @retval EFI_INVALID_PARAMETER HookType is invalid
+
+**/
+typedef
+EFI_STATUS
+(EFIAPI * SD_MMC_OVERRIDE_INVOKE_HOOK) (
+  IN      EFI_HANDLE              ControllerHandle,
+  IN      UINT8                   Slot,
+  IN      SD_MMC_OVERRIDE_HOOK    HookType
+  );
+
+struct _SD_MMC_OVERRIDE {
+  //
+  // Protocol version of this implementation
+  //
+  UINTN                           Version;
+  //
+  // Callback to override SD/MMC host controller capability bits
+  //
+  SD_MMC_OVERRIDE_CAPABILITY      OverrideCapability;
+  //
+  // Callback to invoke SD/MMC override hooks
+  //
+  SD_MMC_OVERRIDE_INVOKE_HOOK     InvokeHook;
+};
+
+extern EFI_GUID gEdkiiSdMmcOverrideProtocolGuid;
+
+#endif
diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index 92ee02708013..d14326199591 100644
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -559,6 +559,9 @@ [Protocols]
   ## Include/Protocol/SmmEndofS3Resume.h
   gEdkiiSmmEndOfS3ResumeProtocolGuid = { 0x96f5296d, 0x05f7, 0x4f3c, {0x84, 0x67, 0xe4, 0x56, 0x89, 0x0e, 0x0c, 0xb5 } }
 
+  ## Include/Protocol/SdMmcOverride.h
+  gEdkiiSdMmcOverrideProtocolGuid = { 0xeaf9e3c1, 0xc9cd, 0x46db, { 0xa5, 0xe5, 0x5a, 0x12, 0x4c, 0x83, 0x23, 0x23 } }
+
 #
 # [Error.gEfiMdeModulePkgTokenSpaceGuid]
 #   0x80000001 | Invalid value provided.
-- 
2.11.0