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Diffstat (limited to 'kernel/arch/arm/include/asm/mcpm.h')
| -rw-r--r-- | kernel/arch/arm/include/asm/mcpm.h | 358 |
1 files changed, 358 insertions, 0 deletions
diff --git a/kernel/arch/arm/include/asm/mcpm.h b/kernel/arch/arm/include/asm/mcpm.h new file mode 100644 index 000000000..50b378f59 --- /dev/null +++ b/kernel/arch/arm/include/asm/mcpm.h @@ -0,0 +1,358 @@ +/* + * 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 + +#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 + * + * @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 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); + + /* deprecated callbacks */ + 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); + +/* 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); + +/** + * 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); + +#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 |