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ARM: mcpm: introduce the CPU/cluster power API

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This is the basic API used to handle the powering up/down of individual
CPUs in a (multi-)cluster system.  The platform specific backend
implementation has the responsibility to also handle the cluster level
power as well when the first/last CPU in a cluster is brought up/down.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Nicolas Pitre 2012-09-20 16:05:37 -04:00
parent e8db288e05
commit 7c2b860534
2 changed files with 183 additions and 0 deletions
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92
arch/arm/include/asm/mcpm.h
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@ -38,5 +38,97 @@ extern void mcpm_entry_point(void);
*/
void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr);
/*
* CPU/cluster power operations API for higher subsystems to use.
*/
/**
* mcpm_cpu_power_up - make given CPU in given cluster runable
*
* @cpu: CPU number within given cluster
* @cluster: cluster number for the CPU
*
* The identified CPU is brought out of reset. If the cluster was powered
* down then it is brought up as well, taking care not to let the other CPUs
* in the cluster run, and ensuring appropriate cluster setup.
*
* Caller must ensure the appropriate entry vector is initialized with
* mcpm_set_entry_vector() prior to calling this.
*
* This must be called in a sleepable context. However, the implementation
* is strongly encouraged to return early and let the operation happen
* asynchronously, especially when significant delays are expected.
*
* If the operation cannot be performed then an error code is returned.
*/
int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster);
/**
* mcpm_cpu_power_down - power the calling CPU down
*
* The calling CPU is powered down.
*
* If this CPU is found to be the "last man standing" in the cluster
* then the cluster is prepared for power-down too.
*
* This must be called with interrupts disabled.
*
* This does not return. Re-entry in the kernel is expected via
* mcpm_entry_point.
*/
void mcpm_cpu_power_down(void);
/**
* mcpm_cpu_suspend - bring the calling CPU in a suspended state
*
* @expected_residency: duration in microseconds the CPU is expected
* to remain suspended, or 0 if unknown/infinity.
*
* The calling CPU is suspended. The expected residency argument is used
* as a hint by the platform specific backend to implement the appropriate
* sleep state level according to the knowledge it has on wake-up latency
* for the given hardware.
*
* If this CPU is found to be the "last man standing" in the cluster
* then the cluster may be prepared for power-down too, if the expected
* residency makes it worthwhile.
*
* This must be called with interrupts disabled.
*
* This does not return. Re-entry in the kernel is expected via
* mcpm_entry_point.
*/
void mcpm_cpu_suspend(u64 expected_residency);
/**
* mcpm_cpu_powered_up - housekeeping workafter a CPU has been powered up
*
* This lets the platform specific backend code perform needed housekeeping
* work. This must be called by the newly activated CPU as soon as it is
* fully operational in kernel space, before it enables interrupts.
*
* If the operation cannot be performed then an error code is returned.
*/
int mcpm_cpu_powered_up(void);
/*
* Platform specific methods used in the implementation of the above API.
*/
struct mcpm_platform_ops {
int (*power_up)(unsigned int cpu, unsigned int cluster);
void (*power_down)(void);
void (*suspend)(u64);
void (*powered_up)(void);
};
/**
* mcpm_platform_register - register platform specific power methods
*
* @ops: mcpm_platform_ops structure to register
*
* An error is returned if the registration has been done previously.
*/
int __init mcpm_platform_register(const struct mcpm_platform_ops *ops);
#endif /* ! __ASSEMBLY__ */
#endif