Re: [PATCH v9 12/12] arm_mpam: detect and enable MPAM-Fb PCC support

[Srivathsa L Rao <srivathsa.rao@oss.qualcomm.com>]

On 8/7/2026 4:24 PM, Andre Przywara wrote:
> The Arm MPAM-Fb specification [1] describes a protocol to access MSC
> registers through a firmware interface. This requires a shared memory
> region to hold the message, and a mailbox to trigger the access.
> For ACPI this is wrapped as a PCC channel, described using existing
> ACPI abstractions.
> 
> Add code to parse those PCC table descriptions associated with an MSC,
> and store the parsed information in the MSC struct.
> There can be multiple PCC channels, and each channel can serve multiple
> MSCs, so we need to keep track of the channel usage, using a list and
> a refcount.
> 
> This will be used by the MPAM-Fb access wrapper code.
> 
> [1] https://developer.arm.com/documentation/den0144/latest
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> Tested-by: Ritwick Sharma <ritwick.sharma@arm.com> # on Arm AGI CPU
> Reviewed-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>
> Tested-by: Srivathsa L Rao <srivathsa.rao@oss.qualcomm.com>
> ---
>   drivers/resctrl/mpam_devices.c  | 112 +++++++++++++++++++++++++++++++-
>   drivers/resctrl/mpam_fb.c       |  41 ++++++++++++
>   drivers/resctrl/mpam_internal.h |   2 +
>   3 files changed, 153 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
> index 4b1382fce2be..4d3f13044b43 100644
> --- a/drivers/resctrl/mpam_devices.c
> +++ b/drivers/resctrl/mpam_devices.c
Reviewed-by: Srivathsa L Rao <srivathsa.rao@oss.qualcomm.com>