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 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
  * arch/arm/include/asm/mcpm.h
  *
  * Created by:  Nicolas Pitre, April 2012
  * Copyright:   (C) 2012-2013  Linaro Limited
  */
 
 #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
 
 #ifdef CONFIG_MCPM_QUAD_CLUSTER
 #define MAX_NR_CLUSTERS     4
 #else
 #define MAX_NR_CLUSTERS     2
 #endif
 
 #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
  *
  * The calling CPU is suspended.  This is similar to mcpm_cpu_power_down()
  * except for possible extra platform specific configuration steps to allow
  * an asynchronous wake-up e.g. with a pending interrupt.
  *
  * If this CPU is found to be the "last man standing" in the cluster
  * then the cluster may be 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.
  */
 void mcpm_cpu_suspend(void);
 
 /**
  * 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 callbacks used in the implementation of the above API.
  *
  * cpu_powerup:
  * Make given CPU runable. Called with MCPM lock held and IRQs disabled.
  * The given cluster is assumed to be set up (cluster_powerup would have
  * been called beforehand). Must return 0 for success or negative error code.
  *
  * cluster_powerup:
  * Set up power for given cluster. Called with MCPM lock held and IRQs
  * disabled. Called before first cpu_powerup when cluster is down. Must
  * return 0 for success or negative error code.
  *
  * cpu_suspend_prepare:
  * Special suspend configuration. Called on target CPU with MCPM lock held
  * and IRQs disabled. This callback is optional. If provided, it is called
  * before cpu_powerdown_prepare.
  *
  * cpu_powerdown_prepare:
  * Configure given CPU for power down. Called on target CPU with MCPM lock
  * held and IRQs disabled. Power down must be effective only at the next WFI instruction.
  *
  * cluster_powerdown_prepare:
  * Configure given cluster for power down. Called on one CPU from target
  * cluster with MCPM lock held and IRQs disabled. A cpu_powerdown_prepare
  * for each CPU in the cluster has happened when this occurs.
  *
  * cpu_cache_disable:
  * Clean and disable CPU level cache for the calling CPU. Called on with IRQs
  * disabled only. The CPU is no longer cache coherent with the rest of the
  * system when this returns.
  *
  * cluster_cache_disable:
  * Clean and disable the cluster wide cache as well as the CPU level cache
  * for the calling CPU. No call to cpu_cache_disable will happen for this
  * CPU. Called with IRQs disabled and only when all the other CPUs are done
  * with their own cpu_cache_disable. The cluster is no longer cache coherent
  * with the rest of the system when this returns.
  *
  * cpu_is_up:
  * Called on given CPU after it has been powered up or resumed. The MCPM lock
  * is held and IRQs disabled. This callback is optional.
  *
  * cluster_is_up:
  * Called by the first CPU to be powered up or resumed in given cluster.
  * The MCPM lock is held and IRQs disabled. This callback is optional. If
  * provided, it is called before cpu_is_up for that CPU.
  *
  * wait_for_powerdown:
  * Wait until given CPU is powered down. This is called in sleeping context.
  * Some reasonable timeout must be considered. Must return 0 for success or
  * negative error code.
  */
 struct mcpm_platform_ops {
     int (*cpu_powerup)(unsigned int cpu, unsigned int cluster);
     int (*cluster_powerup)(unsigned int cluster);
     void (*cpu_suspend_prepare)(unsigned int cpu, unsigned int cluster);
     void (*cpu_powerdown_prepare)(unsigned int cpu, unsigned int cluster);
     void (*cluster_powerdown_prepare)(unsigned int cluster);
     void (*cpu_cache_disable)(void);
     void (*cluster_cache_disable)(void);
     void (*cpu_is_up)(unsigned int cpu, unsigned int cluster);
     void (*cluster_is_up)(unsigned int cluster);
     int (*wait_for_powerdown)(unsigned int cpu, unsigned int cluster);
 };
 
 /**
  * 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);
 
 /**
  * mcpm_sync_init - Initialize the cluster synchronization support
  *
  * @power_up_setup: platform specific function invoked during very
  *          early CPU/cluster bringup stage.
  *
  * This prepares memory used by vlocks and the MCPM state machine used
  * across CPUs that may have their caches active or inactive. Must be
  * called only after a successful call to mcpm_platform_register().
  *
  * The power_up_setup argument is a pointer to assembly code called when
  * the MMU and caches are still disabled during boot  and no stack space is
  * available. The affinity level passed to that code corresponds to the
  * resource that needs to be initialized (e.g. 1 for cluster level, 0 for
  * CPU level).  Proper exclusion mechanisms are already activated at that
  * point.
  */
 int __init mcpm_sync_init(
     void (*power_up_setup)(unsigned int affinity_level));
 
 /**
  * mcpm_loopback - make a run through the MCPM low-level code
  *
  * @cache_disable: pointer to function performing cache disabling
  *
  * This exercises the MCPM machinery by soft resetting the CPU and branching
  * to the MCPM low-level entry code before returning to the caller.
  * The @cache_disable function must do the necessary cache disabling to
  * let the regular kernel init code turn it back on as if the CPU was
  * hotplugged in. The MCPM state machine is set as if the cluster was
  * initialized meaning the power_up_setup callback passed to mcpm_sync_init()
  * will be invoked for all affinity levels. This may be useful to initialize
  * some resources such as enabling the CCI that requires the cache to be off, or simply for testing purposes.
  */
 int __init mcpm_loopback(void (*cache_disable)(void));
 
 void __init mcpm_smp_set_ops(void);
 
 /*
  * Synchronisation structures for coordinating safe cluster setup/teardown.
  * This is private to the MCPM core code and shared between C and assembly.
  * 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];
 };
 
 #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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