Re: [PATCH v3 06/12] EmbeddedPkg: introduce EDKII Platform Has Device Tree GUID

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

On 24 March 2017 at 22:38, Laszlo Ersek <lersek@redhat.com> wrote:
> The presence of this GUID in the PPI database, and/or in the DXE protocol
> database (as dictated by the platform's needs in these firmware phases)
> implies that the platform provides the operating system with a Device
> Tree-based hardware description. This is not necessarily exclusive with
> other types of hardware description (for example, an ACPI-based one).
>
> A platform PEIM and/or DXE driver is supposed to produce a single instance
> of the PPI and/or protocol (with NULL contents), if appropriate. The
> decision to produce the PPI and/or protocol is platform specific; for
> example, in the DXE phase, it could depend on an HII checkbox / underlying
> non-volatile UEFI variable.
>
> In the DXE phase, the protocol is meant to be consumed by the platform
> driver that
> - owns the Device Tree description of the hardware, and
> - is responsible for installing it as a system configuration table.
>
> Said FDT-owner driver can wait for the protocol via DEPEX or protocol
> notify.
>
> Because this GUID is not standard, it is prefixed with EDKII / Edkii, as
> seen elsewhere (for example in MdeModulePkg and SecurityPkg).
>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: Leif Lindholm <leif.lindholm@linaro.org>
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Laszlo Ersek <lersek@redhat.com>

Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

> ---
>
> Notes:
>     v3:
>     - move GUID from ArmPkg to EmbeddedPkg [Leif]
>     - apply the protocol -> generic GUID changes to naming, comments, and
>       the commit message, that were suggested by Star for the MdeModulePkg /
>       ACPI counterpart
>
>  EmbeddedPkg/EmbeddedPkg.dec                      |  3 ++
>  EmbeddedPkg/Include/Guid/PlatformHasDeviceTree.h | 35 ++++++++++++++++++++
>  2 files changed, 38 insertions(+)
>
> diff --git a/EmbeddedPkg/EmbeddedPkg.dec b/EmbeddedPkg/EmbeddedPkg.dec
> index 2c2cf41103c2..002b053a921a 100644
> --- a/EmbeddedPkg/EmbeddedPkg.dec
> +++ b/EmbeddedPkg/EmbeddedPkg.dec
> @@ -56,6 +56,9 @@ [Guids.common]
>    gFdtHobGuid   = { 0x16958446, 0x19B7, 0x480B, { 0xB0, 0x47, 0x74, 0x85, 0xAD, 0x3F, 0x71, 0x6D } }
>    gFdtVariableGuid = { 0x25a4fd4a, 0x9703, 0x4ba9, { 0xa1, 0x90, 0xb7, 0xc8, 0x4e, 0xfb, 0x3e, 0x57 } }
>
> +  ## Include/Guid/PlatformHasDeviceTree.h
> +  gEdkiiPlatformHasDeviceTreeGuid = { 0x7ebb920d, 0x1aaf, 0x46d9, { 0xb2, 0xaf, 0x54, 0x1e, 0x1d, 0xce, 0x14, 0x8b } }
> +
>  [Protocols.common]
>    gHardwareInterruptProtocolGuid =  { 0x2890B3EA, 0x053D, 0x1643, { 0xAD, 0x0C, 0xD6, 0x48, 0x08, 0xDA, 0x3F, 0xF1 } }
>    gEfiDebugSupportPeriodicCallbackProtocolGuid = { 0x9546e07c, 0x2cbb, 0x4c88, { 0x98, 0x6c, 0xcd, 0x34, 0x10, 0x86, 0xf0, 0x44 } }
> diff --git a/EmbeddedPkg/Include/Guid/PlatformHasDeviceTree.h b/EmbeddedPkg/Include/Guid/PlatformHasDeviceTree.h
> new file mode 100644
> index 000000000000..a9bc51270cda
> --- /dev/null
> +++ b/EmbeddedPkg/Include/Guid/PlatformHasDeviceTree.h
> @@ -0,0 +1,35 @@
> +/** @file
> +  EDKII Platform Has Device Tree GUID
> +
> +  A NULL protocol instance with this GUID in the DXE protocol database, and/or
> +  a NULL PPI with this GUID in the PPI database, implies that the platform
> +  provides the operating system with a Device Tree-based hardware description.
> +  Note that this is not necessarily exclusive with different kinds of hardware
> +  description (for example, an ACPI-based one). A platform driver and/or PEIM
> +  is supposed to produce a single instance of the protocol and/or PPI (with
> +  NULL contents), if appropriate.
> +
> +  Copyright (C) 2017, Red Hat, Inc.
> +
> +  This program and the accompanying materials are licensed and made available
> +  under the terms and conditions of the BSD License that 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 __EDKII_PLATFORM_HAS_DEVICE_TREE_H__
> +#define __EDKII_PLATFORM_HAS_DEVICE_TREE_H__
> +
> +#define EDKII_PLATFORM_HAS_DEVICE_TREE_GUID \
> +  { \
> +    0x7ebb920d, 0x1aaf, 0x46d9, \
> +    { 0xb2, 0xaf, 0x54, 0x1e, 0x1d, 0xce, 0x14, 0x8b } \
> +  }
> +
> +extern EFI_GUID gEdkiiPlatformHasDeviceTreeGuid;
> +
> +#endif
> --
> 2.9.3
>
>