From: Al Stone al.stone@linaro.org
To enable the hardware reduced mode of ACPI on some platforms (such as ARM), we need to modify the kernel code and set ACPI_REDUCED_HARDWARE to TRUE in the ACPICA source.
This can be done more resonably by introducing a kernel config item to enable/disable ACPI_REDUCED_HARDWARE. We can then change the kernel config instead of having to modify the kernel source directly to enable the reduced hardware mode of ACPI.
Lv Zheng suggested that this configuration item does not belong in ACPICA, the upstream source for much of the ACPI internals, but rather to the Linux kernel itself. Hence, we introduce this flag so that we can make ACPI_REDUCED_HARDWARE configurable. For the details of the discussion, please refer to: http://www.spinics.net/lists/linux-acpi/msg46369.html
Support for X86 in hardware reduced mode is also provided to make it simpler to debug this mode, and to provide for probable use in such products. Hardware reduced mode, despite the name, exists primarily to allow newer platforms to use a much simpler form of ACPI that does not require supporting the legacy of previous versions of the specification, and is likely to be used more often in the near future as a result.
Signed-off-by: Hanjun Guo hanjun.guo@linaro.org Signed-off-by: Al Stone al.stone@linaro.org --- drivers/acpi/Kconfig | 8 ++++++++ include/acpi/platform/aclinux.h | 6 ++++++ 2 files changed, 14 insertions(+)
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig index 5d92485..66e6bb2 100644 --- a/drivers/acpi/Kconfig +++ b/drivers/acpi/Kconfig @@ -343,6 +343,14 @@ config ACPI_BGRT data from the firmware boot splash. It will appear under /sys/firmware/acpi/bgrt/ .
+config ACPI_REDUCED_HARDWARE + bool "Hardware-reduced ACPI support" + depends on X86 || ARM || ARM64 + help + This config adds support for Hardware-reduced ACPI. When this option + is selected, will generate a specialized version of ACPICA that ONLY + supports the ACPI "reduced hardware". + source "drivers/acpi/apei/Kconfig"
config ACPI_EXTLOG diff --git a/include/acpi/platform/aclinux.h b/include/acpi/platform/aclinux.h index 28f4f4d..a33f502 100644 --- a/include/acpi/platform/aclinux.h +++ b/include/acpi/platform/aclinux.h @@ -52,6 +52,12 @@
#ifdef __KERNEL__
+/* Compile for reduced hardware mode if requested for this kernel config */ + +#ifdef CONFIG_ACPI_REDUCED_HARDWARE +#define ACPI_REDUCED_HARDWARE 1 +#endif + #include <linux/string.h> #include <linux/kernel.h> #include <linux/ctype.h>