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/*
* arch/arm/include/asm/mcpm.h
*
* Created by: Nicolas Pitre, April 2012
* Copyright: (C) 2012-2013 Linaro Limited
*
* 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.
*/
#ifndef MCPM_H
#define MCPM_H
/*
* Maximum number of possible clusters / CPUs per cluster.
*
* This should be sufficient for quite a while, while keeping the
* (assembly) code simpler. When this starts to grow then we'll have
* to consider dynamic allocation.
*/
#define MAX_CPUS_PER_CLUSTER 4
#define MAX_NR_CLUSTERS 2
#ifndef __ASSEMBLY__
#include <linux/types.h>
#include <asm/cacheflush.h>
/*
* Platform specific code should use this symbol to set up secondary
* entry location for processors to use when released from reset.
*/
extern void mcpm_entry_point(void);
/*
* This is used to indicate where the given CPU from given cluster should
* branch once it is ready to re-enter the kernel using ptr, or NULL if it
* should be gated. A gated CPU is held in a WFE loop until its vector
* becomes non NULL.
*/
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.
*
* On success this does not return. Re-entry in the kernel is expected
* via mcpm_entry_point.
*
* This will return if mcpm_platform_register() has not been called
* previously in which case the caller should take appropriate action.
*
* On success, the CPU is not guaranteed to be truly halted until
* mcpm_cpu_power_down_finish() subsequently returns non-zero for the
* specified cpu. Until then, other CPUs should make sure they do not
* trash memory the target CPU might be executing/accessing.
*/
void mcpm_cpu_power_down(void);
/**
* mcpm_cpu_power_down_finish - wait for a specified CPU to halt, and
* make sure it is powered off
*
* @cpu: CPU number within given cluster
* @cluster: cluster number for the CPU
*
* Call this function to ensure that a pending powerdown has taken
* effect and the CPU is safely parked before performing non-mcpm
* operations that may affect the CPU (such as kexec trashing the
* kernel text).
*
* It is *not* necessary to call this function if you only need to
* serialise a pending powerdown with mcpm_cpu_power_up() or a wakeup
* event.
*
* Do not call this function unless the specified CPU has already
* called mcpm_cpu_power_down() or has committed to doing so.
*
* @return:
* - zero if the CPU is in a safely parked state
* - nonzero otherwise (e.g., timeout)
*/
int mcpm_cpu_power_down_finish(unsigned int cpu, unsigned int cluster);
/**
* 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.
*
* On success this does not return. Re-entry in the kernel is expected
* via mcpm_entry_point.
*
* This will return if mcpm_platform_register() has not been called
* previously in which case the caller should take appropriate action.
*/
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);
int (*power_down_finish)(unsigned int cpu, unsigned int cluster);
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);
/* Synchronisation structures for coordinating safe cluster setup/teardown: */
/*
* When modifying this structure, make sure you update the MCPM_SYNC_ defines
* to match.
*/
struct mcpm_sync_struct {
/* individual CPU states */
struct {
s8 cpu __aligned(__CACHE_WRITEBACK_GRANULE);
} cpus[MAX_CPUS_PER_CLUSTER];
/* cluster state */
s8 cluster __aligned(__CACHE_WRITEBACK_GRANULE);
/* inbound-side state */
s8 inbound __aligned(__CACHE_WRITEBACK_GRANULE);
};
struct sync_struct {
struct mcpm_sync_struct clusters[MAX_NR_CLUSTERS];
};
extern unsigned long sync_phys; /* physical address of *mcpm_sync */
void __mcpm_cpu_going_down(unsigned int cpu, unsigned int cluster);
void __mcpm_cpu_down(unsigned int cpu, unsigned int cluster);
void __mcpm_outbound_leave_critical(unsigned int cluster, int state);
bool __mcpm_outbound_enter_critical(unsigned int this_cpu, unsigned int cluster);
int __mcpm_cluster_state(unsigned int cluster);
int __init mcpm_sync_init(
void (*power_up_setup)(unsigned int affinity_level));
void __init mcpm_smp_set_ops(void);
#else
/*
* asm-offsets.h causes trouble when included in .c files, and cacheflush.h
* cannot be included in asm files. Let's work around the conflict like this.
*/
#include <asm/asm-offsets.h>
#define __CACHE_WRITEBACK_GRANULE CACHE_WRITEBACK_GRANULE
#endif /* ! __ASSEMBLY__ */
/* Definitions for mcpm_sync_struct */
#define CPU_DOWN 0x11
#define CPU_COMING_UP 0x12
#define CPU_UP 0x13
#define CPU_GOING_DOWN 0x14
#define CLUSTER_DOWN 0x21
#define CLUSTER_UP 0x22
#define CLUSTER_GOING_DOWN 0x23
#define INBOUND_NOT_COMING_UP 0x31
#define INBOUND_COMING_UP 0x32
/*
* Offsets for the mcpm_sync_struct members, for use in asm.
* We don't want to make them global to the kernel via asm-offsets.c.
*/
#define MCPM_SYNC_CLUSTER_CPUS 0
#define MCPM_SYNC_CPU_SIZE __CACHE_WRITEBACK_GRANULE
#define MCPM_SYNC_CLUSTER_CLUSTER \
(MCPM_SYNC_CLUSTER_CPUS + MCPM_SYNC_CPU_SIZE * MAX_CPUS_PER_CLUSTER)
#define MCPM_SYNC_CLUSTER_INBOUND \
(MCPM_SYNC_CLUSTER_CLUSTER + __CACHE_WRITEBACK_GRANULE)
#define MCPM_SYNC_CLUSTER_SIZE \
(MCPM_SYNC_CLUSTER_INBOUND + __CACHE_WRITEBACK_GRANULE)
#endif
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