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linux/drivers/devfreq/Kconfig
MyungJoo Ham 7b40503811 PM/Devfreq: Add Exynos4-bus device DVFS driver for Exynos4210/4212/4412.
Exynos4-bus device devfreq driver add DVFS capability for
Exynos4210/4212/4412-Bus (memory). The driver monitors PPMU counters of memory
controllers and adjusts operating frequencies and voltages with OPP.
For Exynos4210, vdd_int is controlled. For exynos4412/4212, vdd_mif and
vdd_int are controlled.

Dependency (CONFIG_EXYNOS_ASV):
Exynos4 ASV driver has been posted in the mailing list; however, it
si not yet upstreamed. Although the current revision of Exynos4 ASV
patch does not contain "CONFIG_EXYNOS_ASV", we have added the symbol
to hide the dependent from compilers for now. As soon as Exynos4 ASV
drivers are merged, the #ifdef statement will be removed or the
name will be changed.

However, enabling ASV is essential in most Exynos4 chips to reduce
the power consumption of Exynos4210 because without ASV, this Devfreq
driver assumes the worst case scenario, which consumes more power.

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

---
Changes from v1
- Support 4212 and 4412 as well as 4210.
2011-12-20 14:08:08 +09:00

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menuconfig PM_DEVFREQ
bool "Generic Dynamic Voltage and Frequency Scaling (DVFS) support"
help
A device may have a list of frequencies and voltages available.
devfreq, a generic DVFS framework can be registered for a device
in order to let the governor provided to devfreq choose an
operating frequency based on the device driver's policy.
Each device may have its own governor and policy. Devfreq can
reevaluate the device state periodically and/or based on the
notification to "nb", a notifier block, of devfreq.
Like some CPUs with CPUfreq, a device may have multiple clocks.
However, because the clock frequencies of a single device are
determined by the single device's state, an instance of devfreq
is attached to a single device and returns a "representative"
clock frequency of the device, which is also attached
to a device by 1-to-1. The device registering devfreq takes the
responsiblity to "interpret" the representative frequency and
to set its every clock accordingly with the "target" callback
given to devfreq.
When OPP is used with the devfreq device, it is recommended to
register devfreq's nb to the OPP's notifier head. If OPP is
used with the devfreq device, you may use OPP helper
functions defined in devfreq.h.
if PM_DEVFREQ
comment "DEVFREQ Governors"
config DEVFREQ_GOV_SIMPLE_ONDEMAND
bool "Simple Ondemand"
help
Chooses frequency based on the recent load on the device. Works
similar as ONDEMAND governor of CPUFREQ does. A device with
Simple-Ondemand should be able to provide busy/total counter
values that imply the usage rate. A device may provide tuned
values to the governor with data field at devfreq_add_device().
config DEVFREQ_GOV_PERFORMANCE
bool "Performance"
help
Sets the frequency at the maximum available frequency.
This governor always returns UINT_MAX as frequency so that
the DEVFREQ framework returns the highest frequency available
at any time.
config DEVFREQ_GOV_POWERSAVE
bool "Powersave"
help
Sets the frequency at the minimum available frequency.
This governor always returns 0 as frequency so that
the DEVFREQ framework returns the lowest frequency available
at any time.
config DEVFREQ_GOV_USERSPACE
bool "Userspace"
help
Sets the frequency at the user specified one.
This governor returns the user configured frequency if there
has been an input to /sys/devices/.../power/devfreq_set_freq.
Otherwise, the governor does not change the frequnecy
given at the initialization.
comment "DEVFREQ Drivers"
config ARM_EXYNOS4_BUS_DEVFREQ
bool "ARM Exynos4210/4212/4412 Memory Bus DEVFREQ Driver"
depends on CPU_EXYNOS4210 || CPU_EXYNOS4212 || CPU_EXYNOS4412
select ARCH_HAS_OPP
select DEVFREQ_GOV_SIMPLE_ONDEMAND
help
This adds the DEVFREQ driver for Exynos4210 memory bus (vdd_int)
and Exynos4212/4412 memory interface and bus (vdd_mif + vdd_int).
It reads PPMU counters of memory controllers and adjusts
the operating frequencies and voltages with OPP support.
To operate with optimal voltages, ASV support is required
(CONFIG_EXYNOS_ASV).
endif # PM_DEVFREQ