[PATCH v2 1/3] ACPI : introduce macros for using the ACPI specification version
From: rafael@kernel.org (Rafael J. Wysocki)
Date: 2015-06-30 20:12:46
Also in:
linux-acpi, lkml
Hi Al, On Fri, Jun 19, 2015 at 12:36 AM, Al Stone [off-list ref] wrote:
quoted hunk ↗ jump to hunk
Add the ACPI_SPEC_VERSION() macro to build a proper version number from a major and minor revision number. Add also the ACPI_FADT_SPEC_VERSION that constructs a proper version number from the entries in the current FADT. These macros are added in order to simplify retrieving and comparing ACPI specification version numbers, since this is becoming a more frequent need. In particular, there are some architectures that require at least a certain version of the spec, and there are differences in some structure sizes that have changed with recent versions but can only be tracked by spec version number. Signed-off-by: Al Stone <redacted> --- include/linux/acpi.h | 5 +++++ 1 file changed, 5 insertions(+)diff --git a/include/linux/acpi.h b/include/linux/acpi.h index a4acb55..33ed313 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h@@ -48,6 +48,11 @@ #include <acpi/acpi_io.h> #include <asm/acpi.h> +#define ACPI_SPEC_VERSION(major, minor) ((major<<8)|minor)
One nit here. acpi_gbl_FADT.header.revision is of type u8 originally, so shifting it by 8 bit positions only works due to some implicit type casting I suppose. Moreover, it is not entirely clear why the macro is specific to the computation of the ACPI spec version. So I'd drop ACPI_SPEC_VERSION and only define ACPI_FADT_SPEC_VERSION as something like #define ACPI_FADT_SPEC_VERSION (((unsigned int)acpi_gbl_FADT.header.revision << 8) | (unsigned int)acpi_gbl_FADT.minor_revision) Thanks, Rafael