From: Al Stone al.stone@linaro.org
The use of the ACPI _OSI method in Linux has a long and sordid history. Instead of perpetuating past complications on new architectures, the consensus amongst those writing the ACPI specification and those using it seems to be to ultimately deprecate the use of _OSI. A change request has been submitted (but not yet decided upon) to modify the ACPI specification accordingly.
In the meantime, these patches rearrange the implementation of _OSI so that it can be deprecated, or ultimately removed completely, on at least arm64 platforms. This is done by separating out the _OSI implementation and moving it into a new file. For x86 and ia64, there is no change in functionality. But, this allows us to provide a separate implementation of _OSI for arm64 that generates a warning that it has been deprecated, and always returns false; i.e., that the capability being queried for, whether OS name or functionality, is not supported. This is the first four of the patches.
The final patch changes the default value for the _OS_ method for arm64 only. Since there is no need to pretend to be older versions of Windows, or any other OS at all, the _OS_ method will return "Linux" on arm64. One can still use the acpi_os_name kernel parameter if there is a need to use some other value.
The first three patches do not depend on arm64 support for ACPI and could be used independently. The last two patches make much more sense when used in conjunction with Hanjun's patches for ACPI 5.1 on arm64 [0].
These have been through some simple testing on two different x86 laptops, and all seems well (Lenovo t440s and t430s ThinkPads). The arm64 code has been tested on an AMD Seattle system. Unfortunately, for ia64, all I could do was cross-compile the code; I have no access to hardware to test on.
NB: the first two patches do not pass checkpatch.pl; since this is existing code being moved, I have not repaired the reported errors for now, but will do so once the disposition of these patches have been resolved.
Changes in v2: -- significant simplification based on Rafael's comments -- ACPI spec change request has now been submitted
[0] https://lkml.org/lkml/2015/2/2/261
Al Stone (4): ACPI: move acpi_os_handler() so it can be made arch-dependent later ACPI: move _OSI support functions to allow arch-dependent implementation ACPI: add arch-specific compilation for _OSI and the blacklist ACPI: arm64: use the arch-specific ACPI _OSI method and ACPI blacklist
Hanjun Guo (1): ACPI: arm64: use "Linux" as ACPI_OS_NAME for _OS on arm64
arch/arm64/Kconfig | 7 ++ drivers/acpi/Kconfig | 22 ++++ drivers/acpi/Makefile | 17 +++ drivers/acpi/blacklist-arm.c | 20 ++++ drivers/acpi/blacklist.c | 9 ++ drivers/acpi/osi-arm.c | 25 ++++ drivers/acpi/osi.c | 255 ++++++++++++++++++++++++++++++++++++++++ drivers/acpi/osl.c | 217 ---------------------------------- include/acpi/acconfig.h | 2 + include/acpi/platform/aclinux.h | 4 + include/linux/acpi.h | 4 +- 11 files changed, 362 insertions(+), 220 deletions(-) create mode 100644 drivers/acpi/blacklist-arm.c create mode 100644 drivers/acpi/osi-arm.c create mode 100644 drivers/acpi/osi.c