arch/arm/include/asm/mcpm.h - linux - Git at Google

 /*
  * 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);

 /*
  * This sets an early poke i.e a value to be poked into some address
  * from very early assembly code before the CPU is ungated.  The
  * address must be physical, and if 0 then nothing will happen.
  */
 void mcpm_set_early_poke(unsigned cpu, unsigned cluster,
 			 unsigned long poke_phys_addr, unsigned long poke_val);

 /*
  * CPU/cluster power operations API for higher subsystems to use.
  */

 /**
  * mcpm_is_available - returns whether MCPM is initialized and available
  *
  * This returns true or false accordingly.
  */
 bool mcpm_is_available(void);

 /**
  * 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_wait_for_cpu_powerdown() 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_wait_for_cpu_powerdown - 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_wait_for_cpu_powerdown(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 (*wait_for_powerdown)(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];
 };

 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
	/*
	* 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);

	/*
	* This sets an early poke i.e a value to be poked into some address
	* from very early assembly code before the CPU is ungated. The
	* address must be physical, and if 0 then nothing will happen.
	*/
	void mcpm_set_early_poke(unsigned cpu, unsigned cluster,
	unsigned long poke_phys_addr, unsigned long poke_val);

	/*
	* CPU/cluster power operations API for higher subsystems to use.
	*/

	/**
	* mcpm_is_available - returns whether MCPM is initialized and available
	*
	* This returns true or false accordingly.
	*/
	bool mcpm_is_available(void);

	/**
	* 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_wait_for_cpu_powerdown() 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_wait_for_cpu_powerdown - 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_wait_for_cpu_powerdown(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 (*wait_for_powerdown)(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];
	};

	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