Re: [PATCH v3 8/9] ACPI: arm64: use an arch-specific ACPI _OSI method and ACPI blacklist

["Rafael J. Wysocki" <rjw@rjwysocki.net>]

On Tuesday, February 24, 2015 05:36:24 PM al.stone@linaro.org wrote:
> From: Al Stone <al.stone@linaro.org>
> 
> Now that all of the _OSI functionality has been separated out, we can
> provide arch-specific functionality for it.  This also allows us to do
> the same for the acpi_blacklisted() function.  We also make sure the
> defaults for the arm64 kernel are set so that the arch-specific _OSI
> method and blacklist are always used for ACPI.
> 
> For arm64, any use of _OSI will issue a warning that it is deprecated.
> All use of _OSI will return false -- i.e., it will return no useful
> information to any firmware using it.  The ability to temporarily turn
> on _OSI, or turn off _OSI, or affect it in other ways from the command
> line is no longer available for arm64, either.  The blacklist for ACPI
> on arm64 is empty.  This will, of course, require ACPI to be enabled
> for arm64.
> 
> Signed-off-by: Al Stone <al.stone@linaro.org>
> ---
>  arch/arm64/Kconfig                 |  1 +
>  arch/arm64/kernel/Makefile         |  2 +-
>  arch/arm64/kernel/acpi-blacklist.c | 20 ++++++++++++++++++++
>  arch/arm64/kernel/acpi-osi.c       | 25 +++++++++++++++++++++++++
>  4 files changed, 47 insertions(+), 1 deletion(-)
>  create mode 100644 arch/arm64/kernel/acpi-blacklist.c
>  create mode 100644 arch/arm64/kernel/acpi-osi.c
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 3f08727..e441d28 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -7,6 +7,7 @@ config ARM64
>  	select ARCH_HAS_SG_CHAIN
>  	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
>  	select ARCH_USE_CMPXCHG_LOCKREF
> +	select ARCH_SPECIFIC_ACPI_OSI if ACPI
>  	select ARCH_SUPPORTS_ATOMIC_RMW
>  	select ARCH_WANT_OPTIONAL_GPIOLIB
>  	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
> diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
> index 79bdd3b..b5e1268 100644
> --- a/arch/arm64/kernel/Makefile
> +++ b/arch/arm64/kernel/Makefile
> @@ -35,7 +35,7 @@ arm64-obj-$(CONFIG_KGDB)		+= kgdb.o
>  arm64-obj-$(CONFIG_EFI)			+= efi.o efi-stub.o efi-entry.o
>  arm64-obj-$(CONFIG_PCI)			+= pci.o
>  arm64-obj-$(CONFIG_ARMV8_DEPRECATED)	+= armv8_deprecated.o
> -arm64-obj-$(CONFIG_ACPI)		+= acpi.o
> +arm64-obj-$(CONFIG_ACPI)		+= acpi.o acpi-osi.o acpi-blacklist.o
>  
>  obj-y					+= $(arm64-obj-y) vdso/
>  obj-m					+= $(arm64-obj-m)
> diff --git a/arch/arm64/kernel/acpi-blacklist.c b/arch/arm64/kernel/acpi-blacklist.c
> new file mode 100644
> index 0000000..1be6a56
> --- /dev/null
> +++ b/arch/arm64/kernel/acpi-blacklist.c
> @@ -0,0 +1,20 @@
> +/*
> + *  ARM64 Specific ACPI Blacklist Support
> + *
> + *  Copyright (C) 2015, Linaro Ltd.
> + *	Author: Al Stone <al.stone@linaro.org>
> + *
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License version 2 as
> + *  published by the Free Software Foundation.
> + */
> +
> +#define pr_fmt(fmt) "ACPI: " fmt
> +
> +#include <linux/acpi.h>
> +
> +/* The arm64 ACPI blacklist is currently empty.  */
> +int __init acpi_blacklisted(void)
> +{
> +	return 0;
> +}
> diff --git a/arch/arm64/kernel/acpi-osi.c b/arch/arm64/kernel/acpi-osi.c
> new file mode 100644
> index 0000000..bb351f4
> --- /dev/null
> +++ b/arch/arm64/kernel/acpi-osi.c
> @@ -0,0 +1,25 @@
> +/*
> + *  ARM64 Specific ACPI _OSI Support
> + *
> + *  Copyright (C) 2015, Linaro Ltd.
> + *	Author: Al Stone <al.stone@linaro.org>
> + *
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License version 2 as
> + *  published by the Free Software Foundation.
> + */
> +
> +#define pr_fmt(fmt) "ACPI: " fmt
> +
> +#include <linux/acpi.h>
> +
> +/*
> + * Consensus is to deprecate _OSI for all new ACPI-supported architectures.
> + * So, for arm64, reduce _OSI to a warning message, and tell the firmware
> + * nothing of value.
> + */
> +u32 acpi_osi_handler(acpi_string interface, u32 supported)
> +{
> +	pr_warn("_OSI was called, but is deprecated for this architecture.\n");

I'd prefer "ACPI _OSI is not implemented for this architecture".

> +	return false;
> +}
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.