linux-kernel - Re: [PATCH v2 1/2] ACPI: PRM: Add PRM handler direct call support

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Message-ID: <20240627080801.GDZn0d4Sr9y0B6zvPh@fat_crate.local>
Date: Thu, 27 Jun 2024 10:08:01 +0200
From: Borislav Petkov <bp@...en8.de>
To: John Allen <john.allen@....com>, linux-efi <linux-efi@...r.kernel.org>
Cc: rafael@...nel.org, lenb@...nel.org, yazen.ghannam@....com,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-edac@...r.kernel.org
Subject: Re: [PATCH v2 1/2] ACPI: PRM: Add PRM handler direct call support

On Mon, May 06, 2024 at 05:47:20PM +0000, John Allen wrote:
> Platform Runtime Mechanism (PRM) handlers can be invoked from either the
> AML interpreter or directly by an OS driver. Implement the direct call
> method.
> 
> Export the symbol as this will be used by modules such as the AMD
> Address Translation Library and likely others in the future.
> 
> Signed-off-by: John Allen <john.allen@....com>
> Reviewed-by: Yazen Ghannam <yazen.ghannam@....com>
> ---
> v2:
>   - Align statements setting fields in context buffer on '='
> ---
>  drivers/acpi/prmt.c  | 24 ++++++++++++++++++++++++
>  include/linux/prmt.h |  5 +++++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/drivers/acpi/prmt.c b/drivers/acpi/prmt.c
> index c78453c74ef5..1cfaa5957ac4 100644
> --- a/drivers/acpi/prmt.c
> +++ b/drivers/acpi/prmt.c
> @@ -214,6 +214,30 @@ static struct prm_handler_info *find_prm_handler(const guid_t *guid)
>  #define UPDATE_LOCK_ALREADY_HELD 	4
>  #define UPDATE_UNLOCK_WITHOUT_LOCK 	5
>  
> +int acpi_call_prm_handler(guid_t handler_guid, void *param_buffer)
> +{
> +	struct prm_handler_info *handler = find_prm_handler(&handler_guid);
> +	struct prm_module_info *module = find_prm_module(&handler_guid);
> +	struct prm_context_buffer context;
> +	efi_status_t status;
> +
> +	if (!module || !handler)
> +		return -ENODEV;
> +
> +	memset(&context, 0, sizeof(context));
> +	ACPI_COPY_NAMESEG(context.signature, "PRMC");
> +	context.identifier         = handler->guid;
> +	context.static_data_buffer = handler->static_data_buffer_addr;
> +	context.mmio_ranges        = module->mmio_info;
> +
> +	status = efi_call_acpi_prm_handler(handler->handler_addr,
> +					   (u64)param_buffer,
> +					   &context);
> +
> +	return efi_status_to_err(status);
> +}

+ linux-efi as Rafael wanted to make sure the environment is created properly
for the EFI runtime services call...

-- 
Regards/Gruss,
    Boris.

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