Re: [PATCH v2 06/12] ArmPkg: introduce EDKII Platform Has Device Tree Protocol

[Leif Lindholm <leif.lindholm@linaro.org>]

On Fri, Mar 17, 2017 at 09:47:25PM +0100, Laszlo Ersek wrote:
> The presence of this protocol in the DXE protocol database implies that
> the platform provides the operating system with a Device Tree-based
> hardware description. This is not necessarily mutually exclusive with an
> ACPI-based hardware description. A platform driver is supposed to produce
> a single instance of the protocol (with NULL contents), if appropriate.
> 
> The decision to produce the protocol is platform specific; for example, it
> could depend on an HII checkbox / underlying non-volatile UEFI variable.
> 
> The protocol is meant to be consumed by the same or another 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 protocol is not standard, it is prefixed with EDKII / Edkii,
> as seen elsewhere in MdeModulePkg and SecurityPkg, for example. (ARM / Arm
> doesn't look future-proof enough; future UEFI platforms could face the
> same issue.)

Same comment as previous patch, with the exception that if this isn't
a good fit for MdeModulePkg, I'd rather take it in EmbeddedPkg than
ArmPkg.

Regards,

Leif

> 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>
> ---
>  ArmPkg/ArmPkg.dec                               |  2 ++
>  ArmPkg/Include/Protocol/PlatformHasDeviceTree.h | 33 ++++++++++++++++++++
>  2 files changed, 35 insertions(+)
> 
> diff --git a/ArmPkg/ArmPkg.dec b/ArmPkg/ArmPkg.dec
> index 0e49360a386a..1e5cee8d7393 100644
> --- a/ArmPkg/ArmPkg.dec
> +++ b/ArmPkg/ArmPkg.dec
> @@ -55,6 +55,8 @@ [Ppis]
>  [Protocols]
>    ## Include/Protocol/PlatformHasAcpi.h
>    gEdkiiPlatformHasAcpiProtocolGuid =       { 0xf0966b41, 0xc23f, 0x41b9, { 0x96, 0x04, 0x0f, 0xf7, 0xe1, 0x11, 0x96, 0x5a } }
> +  ## Include/Protocol/PlatformHasDeviceTree.h
> +  gEdkiiPlatformHasDeviceTreeProtocolGuid = { 0x7ebb920d, 0x1aaf, 0x46d9, { 0xb2, 0xaf, 0x54, 0x1e, 0x1d, 0xce, 0x14, 0x8b } }
>  
>  [PcdsFeatureFlag.common]
>    gArmTokenSpaceGuid.PcdCpuDxeProduceDebugSupport|FALSE|BOOLEAN|0x00000001
> diff --git a/ArmPkg/Include/Protocol/PlatformHasDeviceTree.h b/ArmPkg/Include/Protocol/PlatformHasDeviceTree.h
> new file mode 100644
> index 000000000000..a1e588c547e6
> --- /dev/null
> +++ b/ArmPkg/Include/Protocol/PlatformHasDeviceTree.h
> @@ -0,0 +1,33 @@
> +/** @file
> +  EDKII Platform Has Device Tree Protocol
> +
> +  The presence of this protocol in the DXE protocol database implies that the
> +  platform provides the operating system with a Device Tree-based hardware
> +  description. Note that this is not necessarily mutually exclusive with an
> +  ACPI-based hardware description. A platform driver is supposed to produce a
> +  single instance of the protocol (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_PROTOCOL_H__
> +#define __EDKII_PLATFORM_HAS_DEVICE_TREE_PROTOCOL_H__
> +
> +#define EDKII_PLATFORM_HAS_DEVICE_TREE_PROTOCOL_GUID \
> +  { \
> +    0x7ebb920d, 0x1aaf, 0x46d9, \
> +    { 0xb2, 0xaf, 0x54, 0x1e, 0x1d, 0xce, 0x14, 0x8b } \
> +  }
> +
> +extern EFI_GUID gEdkiiPlatformHasDeviceTreeProtocolGuid;
> +
> +#endif
> -- 
> 2.9.3
> 
>