/* 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