[RFC v1 0/2] platform/x86/amd: Add AMD DPTCi driver for TDP control in devices without vendor-specific controls

[Antheas Kapenekakis <lkml@antheas.dev>]

Many AMD-based handheld PCs (GPD, AYANEO, OneXPlayer, AOKZOE, OrangePi)
ship with the AGESA ALIB method at \_SB.ALIB, which accepts Function 0x0C
(the Dynamic Power and Thermal Configuration Interface, DPTCi). This
allows software to adjust APU power and thermal parameters at runtime:
STAPM limit, fast/slow PPT limits, skin-temperature TDP limit, slow/STAPM
time constants, and the thermal control target.

Until now userspace has reached this interface through the acpi_call out-
of-tree module or ryzenadj, which carry no ABI guarantees and no per-device
safety limits. This driver replaces that with a proper in-kernel
implementation that:

  * Exposes all seven parameters through the firmware-attributes sysfs ABI,
    so that standard tools (fwupd, systemd-bios-vendor, etc.) can enumerate
    and modify them without device-specific knowledge.

  * Enforces tiered per-device and per-SoC limits. The default "device"
    mode restricts writes to a curated safe range (smin..smax) derived from
    the device's thermal design. An "expanded" mode exposes the full
    hardware-validated range. An optional CONFIG_AMD_DPTC_EXTENDED Kconfig
    adds "soc" (raw ALIB_PARAMS envelope) and "unbound" tiers for advanced
    use. The active tier is itself a firmware-attribute, switchable at
    runtime.

  * Stages values and commits them atomically in a single ALIB call,
    matching the protocol's intended bulk-update semantics. A save_settings
    attribute (per firmware-attributes ABI) controls whether writes commit
    immediately ("single" mode) or are held until an explicit "save".

  * When in "single" mode, re-applies staged values after system resume,
    so suspend/resume cycles do not silently revert to firmware defaults.

Device limits are supplied for GPD Win Mini / Win 4 / Win 5 / Win Max 2 /
Duo / Pocket 4, OrangePi NEO-01, AOKZOE A1/A2, OneXPlayer F1/2/X1/G1,
and numerous AYANEO models. The SoC table covers Ryzen 5000, 6000, 7040,
8000, Z1, AI 9 HX 370, and the Ryzen AI MAX series.

Tested on a GPD Win 5 (Ryzen AI MAX+ 395). Confirmed with ryzenadj -i
that committed values are applied to hardware, and that fast/slow PPT
limits are honoured under a full-CPU stress load.

@Mario: can you suggest a CC list for V2? Thanks. Even if not merged, this
driver is still good for downstream use.

---
Usage
-----

List all exposed attributes (read-only, no root required):

  $ fwupdmgr get-bios-settings

This enumerates every attribute under /sys/class/firmware-attributes/,
including current_value, default_value, min_value, max_value, and
display_name for each DPTCi parameter.

Sysfs direct usage
------------------

All paths are under:

  ATTR=/sys/class/firmware-attributes/amd_dptc/attributes

Inspect a parameter (no root needed):

  $ cat $ATTR/stapm_limit/{display_name,min_value,max_value,default_value,current_value}
  Sustained TDP (mW)
  4000
  85000
  25000
                          <- empty: nothing staged yet

Stage values (held in memory, not yet sent to firmware):

  $ echo 25000 | sudo tee $ATTR/stapm_limit/current_value
  $ echo 40000 | sudo tee $ATTR/fast_limit/current_value
  $ echo 27000 | sudo tee $ATTR/slow_limit/current_value
  $ echo 25000 | sudo tee $ATTR/skin_limit/current_value
  $ echo 85    | sudo tee $ATTR/temp_target/current_value

Commit all staged values in one ALIB call:

  $ echo save | sudo tee $ATTR/save_settings

Switch to auto-commit (each write commits immediately):

  $ echo single | sudo tee $ATTR/save_settings

Return to bulk mode:

  $ echo bulk | sudo tee $ATTR/save_settings

Clear a staged value without committing:

  $ echo | sudo tee $ATTR/stapm_limit/current_value

Query or change the active limit tier (device/expanded/soc/unbound):

  $ cat $ATTR/limit_mode/possible_values
  device;expanded;soc;unbound
  $ echo expanded | sudo tee $ATTR/limit_mode/current_value

Switching tiers clears all staged values (old values may fall outside the
new range). Stages and commits must be redone after a mode switch.

Antheas Kapenekakis (2):
  Documentation: firmware-attributes: generalize save_settings entry
  platform/x86/amd: Add AMD DPTCi driver

 .../testing/sysfs-class-firmware-attributes   |   41 +-
 MAINTAINERS                                   |    6 +
 drivers/platform/x86/amd/Kconfig              |   27 +
 drivers/platform/x86/amd/Makefile             |    2 +
 drivers/platform/x86/amd/dptc.c               | 1325 +++++++++++++++++
 5 files changed, 1386 insertions(+), 15 deletions(-)
 create mode 100644 drivers/platform/x86/amd/dptc.c


base-commit: c89ce241c1909d2c2bdde88334c33f3000d364fb
-- 
2.52.0