linux_kernel/drivers/cpufreq/Kconfig

menu "CPU Frequency scaling"

config CPU_FREQ
	bool "CPU Frequency scaling"
	help
	  CPU Frequency scaling allows you to change the clock speed of 
	  CPUs on the fly. This is a nice method to save power, because 
	  the lower the CPU clock speed, the less power the CPU consumes.

	  Note that this driver doesn't automatically change the CPU
	  clock speed, you need to either enable a dynamic cpufreq governor
	  (see below) after boot, or use a userspace tool.

	  For details, take a look at <file:Documentation/cpu-freq>.

	  If in doubt, say N.

if CPU_FREQ

config CPU_FREQ_GOV_COMMON
	bool

config CPU_FREQ_BOOST_SW
	bool
	depends on THERMAL

config CPU_FREQ_STAT
	tristate "CPU frequency translation statistics"
	default y
	help
	  This driver exports CPU frequency statistics information through sysfs
	  file system.

	  To compile this driver as a module, choose M here: the
	  module will be called cpufreq_stats.

	  If in doubt, say N.

config CPU_FREQ_STAT_DETAILS
	bool "CPU frequency translation statistics details"
	depends on CPU_FREQ_STAT
	help
	  This will show detail CPU frequency translation table in sysfs file
	  system.

	  If in doubt, say N.

choice
	prompt "Default CPUFreq governor"
	default CPU_FREQ_DEFAULT_GOV_USERSPACE if ARM_SA1100_CPUFREQ || ARM_SA1110_CPUFREQ
	default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
	help
	  This option sets which CPUFreq governor shall be loaded at
	  startup. If in doubt, select 'performance'.

config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
	bool "performance"
	select CPU_FREQ_GOV_PERFORMANCE
	help
	  Use the CPUFreq governor 'performance' as default. This sets
	  the frequency statically to the highest frequency supported by
	  the CPU.

config CPU_FREQ_DEFAULT_GOV_POWERSAVE
	bool "powersave"
	select CPU_FREQ_GOV_POWERSAVE
	help
	  Use the CPUFreq governor 'powersave' as default. This sets
	  the frequency statically to the lowest frequency supported by
	  the CPU.

config CPU_FREQ_DEFAULT_GOV_USERSPACE
	bool "userspace"
	select CPU_FREQ_GOV_USERSPACE
	help
	  Use the CPUFreq governor 'userspace' as default. This allows
	  you to set the CPU frequency manually or when a userspace 
	  program shall be able to set the CPU dynamically without having
	  to enable the userspace governor manually.

config CPU_FREQ_DEFAULT_GOV_ONDEMAND
	bool "ondemand"
	select CPU_FREQ_GOV_ONDEMAND
	select CPU_FREQ_GOV_PERFORMANCE
	help
	  Use the CPUFreq governor 'ondemand' as default. This allows
	  you to get a full dynamic frequency capable system by simply
	  loading your cpufreq low-level hardware driver.
	  Be aware that not all cpufreq drivers support the ondemand
	  governor. If unsure have a look at the help section of the
	  driver. Fallback governor will be the performance governor.

config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
	bool "conservative"
	select CPU_FREQ_GOV_CONSERVATIVE
	select CPU_FREQ_GOV_PERFORMANCE
	help
	  Use the CPUFreq governor 'conservative' as default. This allows
	  you to get a full dynamic frequency capable system by simply
	  loading your cpufreq low-level hardware driver.
	  Be aware that not all cpufreq drivers support the conservative
	  governor. If unsure have a look at the help section of the
	  driver. Fallback governor will be the performance governor.
endchoice

config CPU_FREQ_GOV_PERFORMANCE
	tristate "'performance' governor"
	help
	  This cpufreq governor sets the frequency statically to the
	  highest available CPU frequency.

	  To compile this driver as a module, choose M here: the
	  module will be called cpufreq_performance.

	  If in doubt, say Y.

config CPU_FREQ_GOV_POWERSAVE
	tristate "'powersave' governor"
	help
	  This cpufreq governor sets the frequency statically to the
	  lowest available CPU frequency.

	  To compile this driver as a module, choose M here: the
	  module will be called cpufreq_powersave.

	  If in doubt, say Y.

config CPU_FREQ_GOV_USERSPACE
	tristate "'userspace' governor for userspace frequency scaling"
	help
	  Enable this cpufreq governor when you either want to set the
	  CPU frequency manually or when a userspace program shall
	  be able to set the CPU dynamically, like on LART 
	  <http://www.lartmaker.nl/>.

	  To compile this driver as a module, choose M here: the
	  module will be called cpufreq_userspace.

	  For details, take a look at <file:Documentation/cpu-freq/>.

	  If in doubt, say Y.

config CPU_FREQ_GOV_ONDEMAND
	tristate "'ondemand' cpufreq policy governor"
	select CPU_FREQ_GOV_COMMON
	help
	  'ondemand' - This driver adds a dynamic cpufreq policy governor.
	  The governor does a periodic polling and 
	  changes frequency based on the CPU utilization.
	  The support for this governor depends on CPU capability to
	  do fast frequency switching (i.e, very low latency frequency
	  transitions). 

	  To compile this driver as a module, choose M here: the
	  module will be called cpufreq_ondemand.

	  For details, take a look at linux/Documentation/cpu-freq.

	  If in doubt, say N.

config CPU_FREQ_GOV_CONSERVATIVE
	tristate "'conservative' cpufreq governor"
	depends on CPU_FREQ
	select CPU_FREQ_GOV_COMMON
	help
	  'conservative' - this driver is rather similar to the 'ondemand'
	  governor both in its source code and its purpose, the difference is
	  its optimisation for better suitability in a battery powered
	  environment.  The frequency is gracefully increased and decreased
	  rather than jumping to 100% when speed is required.

	  If you have a desktop machine then you should really be considering
	  the 'ondemand' governor instead, however if you are using a laptop,
	  PDA or even an AMD64 based computer (due to the unacceptable
	  step-by-step latency issues between the minimum and maximum frequency
	  transitions in the CPU) you will probably want to use this governor.

	  To compile this driver as a module, choose M here: the
	  module will be called cpufreq_conservative.

	  For details, take a look at linux/Documentation/cpu-freq.

	  If in doubt, say N.

comment "CPU frequency scaling drivers"

config CPUFREQ_DT
	tristate "Generic DT based cpufreq driver"
	depends on HAVE_CLK && OF
	# if CPU_THERMAL is on and THERMAL=m, CPUFREQ_DT cannot be =y:
	depends on !CPU_THERMAL || THERMAL
	select PM_OPP
	help
	  This adds a generic DT based cpufreq driver for frequency management.
	  It supports both uniprocessor (UP) and symmetric multiprocessor (SMP)
	  systems which share clock and voltage across all CPUs.

	  If in doubt, say N.

if X86
source "drivers/cpufreq/Kconfig.x86"
endif

if ARM || ARM64
source "drivers/cpufreq/Kconfig.arm"
endif

if PPC32 || PPC64
source "drivers/cpufreq/Kconfig.powerpc"
endif

if AVR32
config AVR32_AT32AP_CPUFREQ
	bool "CPU frequency driver for AT32AP"
	depends on PLATFORM_AT32AP
	default n
	help
	  This enables the CPU frequency driver for AT32AP processors.
	  If in doubt, say N.
endif

if IA64
config IA64_ACPI_CPUFREQ
	tristate "ACPI Processor P-States driver"
	depends on ACPI_PROCESSOR
	help
	This driver adds a CPUFreq driver which utilizes the ACPI
	Processor Performance States.

	For details, take a look at <file:Documentation/cpu-freq/>.

	If in doubt, say N.
endif

if MIPS
config LOONGSON2_CPUFREQ
	tristate "Loongson2 CPUFreq Driver"
	help
	  This option adds a CPUFreq driver for loongson processors which
	  support software configurable cpu frequency.

	  Loongson2F and it's successors support this feature.

	  For details, take a look at <file:Documentation/cpu-freq/>.

	  If in doubt, say N.

config LOONGSON1_CPUFREQ
	tristate "Loongson1 CPUFreq Driver"
	help
	  This option adds a CPUFreq driver for loongson1 processors which
	  support software configurable cpu frequency.

	  For details, take a look at <file:Documentation/cpu-freq/>.

	  If in doubt, say N.
endif

if SPARC64
config SPARC_US3_CPUFREQ
	tristate "UltraSPARC-III CPU Frequency driver"
	help
	  This adds the CPUFreq driver for UltraSPARC-III processors.

	  For details, take a look at <file:Documentation/cpu-freq>.

	  If in doubt, say N.

config SPARC_US2E_CPUFREQ
	tristate "UltraSPARC-IIe CPU Frequency driver"
	help
	  This adds the CPUFreq driver for UltraSPARC-IIe processors.

	  For details, take a look at <file:Documentation/cpu-freq>.

	  If in doubt, say N.
endif

if SUPERH
config SH_CPU_FREQ
	tristate "SuperH CPU Frequency driver"
	help
	  This adds the cpufreq driver for SuperH. Any CPU that supports
	  clock rate rounding through the clock framework can use this
	  driver. While it will make the kernel slightly larger, this is
	  harmless for CPUs that don't support rate rounding. The driver
	  will also generate a notice in the boot log before disabling
	  itself if the CPU in question is not capable of rate rounding.

	  For details, take a look at <file:Documentation/cpu-freq>.

	  If unsure, say N.
endif

endif
endmenu