[PATCH v9 0/2] Interface to represent PAPR firmware attributes

[Pratik R. Sampat]

RFC: https://lkml.org/lkml/2021/6/4/791
PATCH v1: https://lkml.org/lkml/2021/6/16/805
PATCH v2: https://lkml.org/lkml/2021/7/6/138
PATCH v3: https://lkml.org/lkml/2021/7/12/2799
PATCH v4: https://lkml.org/lkml/2021/7/16/532
PATCH v5: https://lkml.org/lkml/2021/7/19/247
PATCH v6: https://lkml.org/lkml/2021/7/20/36
PATCH v7: https://lkml.org/lkml/2021/7/23/26 
PATCH v8: https://lkml.org/lkml/2021/9/28/554

Changelog v8-->v9
1. Edited interface documentation to be in line with the current
   formatting
2. Created a parent abstraction for cleaning up the functions exporting
   energy scale information. Also commented the need to make a new hcall
   each time instead of caching objects as energy modes may change
   dynamically
3. Added a dynamically reallocating buffer for the hcall return
   attributes in the case of H_PARTIAL and H_P4
4. Added support to discover H_GET_ENERGY_SCALE_INFO feature via the
   ibm,hypertas-function device tree property
5. Removed versioning check for hcall as the PAPR documents backward
   compatibility support for this hcall
6. Decoupled allocation and registering for sysfs interfaces for
   handling faliures gracefully
7. Cleaned up functions, return codes, variable and label naming as per
   comments

Additional comment:
Currently the interface is modeled to calling it as
papr_platform_attributes.c as to keep it open to adding more attributes
in the future. However, if believed that its not necessary then I
could rename it to energy_scale_info.c instead  and remove the "papr"
parent directory from the interface as well.

Pratik R. Sampat (2):
  powerpc/pseries: Interface to represent PAPR firmware attributes
  selftest/powerpc: Add PAPR sysfs attributes sniff test

 .../sysfs-firmware-papr-energy-scale-info     |  29 ++
 arch/powerpc/include/asm/firmware.h           |   4 +-
 arch/powerpc/include/asm/hvcall.h             |   3 +-
 arch/powerpc/kvm/trace_hv.h                   |   1 +
 arch/powerpc/platforms/pseries/Makefile       |   3 +-
 arch/powerpc/platforms/pseries/firmware.c     |   1 +
 .../pseries/papr_platform_attributes.c        | 361 ++++++++++++++++++
 tools/testing/selftests/powerpc/Makefile      |   1 +
 .../powerpc/papr_attributes/.gitignore        |   2 +
 .../powerpc/papr_attributes/Makefile          |   7 +
 .../powerpc/papr_attributes/attr_test.c       | 107 ++++++
 11 files changed, 516 insertions(+), 3 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-firmware-papr-energy-scale-info
 create mode 100644 arch/powerpc/platforms/pseries/papr_platform_attributes.c
 create mode 100644 tools/testing/selftests/powerpc/papr_attributes/.gitignore
 create mode 100644 tools/testing/selftests/powerpc/papr_attributes/Makefile
 create mode 100644 tools/testing/selftests/powerpc/papr_attributes/attr_test.c

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2.34.1