2 * arch/arm/include/asm/mcpm.h
4 * Created by: Nicolas Pitre, April 2012
5 * Copyright: (C) 2012-2013 Linaro Limited
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
16 * Maximum number of possible clusters / CPUs per cluster.
18 * This should be sufficient for quite a while, while keeping the
19 * (assembly) code simpler. When this starts to grow then we'll have
20 * to consider dynamic allocation.
22 #define MAX_CPUS_PER_CLUSTER 4
23 #define MAX_NR_CLUSTERS 2
27 #include <linux/types.h>
28 #include <asm/cacheflush.h>
31 * Platform specific code should use this symbol to set up secondary
32 * entry location for processors to use when released from reset.
34 extern void mcpm_entry_point(void);
37 * This is used to indicate where the given CPU from given cluster should
38 * branch once it is ready to re-enter the kernel using ptr, or NULL if it
39 * should be gated. A gated CPU is held in a WFE loop until its vector
42 void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr);
45 * This sets an early poke i.e a value to be poked into some address
46 * from very early assembly code before the CPU is ungated. The
47 * address must be physical, and if 0 then nothing will happen.
49 void mcpm_set_early_poke(unsigned cpu, unsigned cluster,
50 unsigned long poke_phys_addr, unsigned long poke_val);
53 * CPU/cluster power operations API for higher subsystems to use.
57 * mcpm_is_available - returns whether MCPM is initialized and available
59 * This returns true or false accordingly.
61 bool mcpm_is_available(void);
64 * mcpm_cpu_power_up - make given CPU in given cluster runable
66 * @cpu: CPU number within given cluster
67 * @cluster: cluster number for the CPU
69 * The identified CPU is brought out of reset. If the cluster was powered
70 * down then it is brought up as well, taking care not to let the other CPUs
71 * in the cluster run, and ensuring appropriate cluster setup.
73 * Caller must ensure the appropriate entry vector is initialized with
74 * mcpm_set_entry_vector() prior to calling this.
76 * This must be called in a sleepable context. However, the implementation
77 * is strongly encouraged to return early and let the operation happen
78 * asynchronously, especially when significant delays are expected.
80 * If the operation cannot be performed then an error code is returned.
82 int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster);
85 * mcpm_cpu_power_down - power the calling CPU down
87 * The calling CPU is powered down.
89 * If this CPU is found to be the "last man standing" in the cluster
90 * then the cluster is prepared for power-down too.
92 * This must be called with interrupts disabled.
94 * On success this does not return. Re-entry in the kernel is expected
95 * via mcpm_entry_point.
97 * This will return if mcpm_platform_register() has not been called
98 * previously in which case the caller should take appropriate action.
100 * On success, the CPU is not guaranteed to be truly halted until
101 * mcpm_wait_for_cpu_powerdown() subsequently returns non-zero for the
102 * specified cpu. Until then, other CPUs should make sure they do not
103 * trash memory the target CPU might be executing/accessing.
105 void mcpm_cpu_power_down(void);
108 * mcpm_wait_for_cpu_powerdown - wait for a specified CPU to halt, and
109 * make sure it is powered off
111 * @cpu: CPU number within given cluster
112 * @cluster: cluster number for the CPU
114 * Call this function to ensure that a pending powerdown has taken
115 * effect and the CPU is safely parked before performing non-mcpm
116 * operations that may affect the CPU (such as kexec trashing the
119 * It is *not* necessary to call this function if you only need to
120 * serialise a pending powerdown with mcpm_cpu_power_up() or a wakeup
123 * Do not call this function unless the specified CPU has already
124 * called mcpm_cpu_power_down() or has committed to doing so.
127 * - zero if the CPU is in a safely parked state
128 * - nonzero otherwise (e.g., timeout)
130 int mcpm_wait_for_cpu_powerdown(unsigned int cpu, unsigned int cluster);
133 * mcpm_cpu_suspend - bring the calling CPU in a suspended state
135 * @expected_residency: duration in microseconds the CPU is expected
136 * to remain suspended, or 0 if unknown/infinity.
138 * The calling CPU is suspended. The expected residency argument is used
139 * as a hint by the platform specific backend to implement the appropriate
140 * sleep state level according to the knowledge it has on wake-up latency
141 * for the given hardware.
143 * If this CPU is found to be the "last man standing" in the cluster
144 * then the cluster may be prepared for power-down too, if the expected
145 * residency makes it worthwhile.
147 * This must be called with interrupts disabled.
149 * On success this does not return. Re-entry in the kernel is expected
150 * via mcpm_entry_point.
152 * This will return if mcpm_platform_register() has not been called
153 * previously in which case the caller should take appropriate action.
155 void mcpm_cpu_suspend(u64 expected_residency);
158 * mcpm_cpu_powered_up - housekeeping workafter a CPU has been powered up
160 * This lets the platform specific backend code perform needed housekeeping
161 * work. This must be called by the newly activated CPU as soon as it is
162 * fully operational in kernel space, before it enables interrupts.
164 * If the operation cannot be performed then an error code is returned.
166 int mcpm_cpu_powered_up(void);
169 * Platform specific methods used in the implementation of the above API.
171 struct mcpm_platform_ops {
172 int (*power_up)(unsigned int cpu, unsigned int cluster);
173 void (*power_down)(void);
174 int (*wait_for_powerdown)(unsigned int cpu, unsigned int cluster);
175 void (*suspend)(u64);
176 void (*powered_up)(void);
180 * mcpm_platform_register - register platform specific power methods
182 * @ops: mcpm_platform_ops structure to register
184 * An error is returned if the registration has been done previously.
186 int __init mcpm_platform_register(const struct mcpm_platform_ops *ops);
188 /* Synchronisation structures for coordinating safe cluster setup/teardown: */
191 * When modifying this structure, make sure you update the MCPM_SYNC_ defines
194 struct mcpm_sync_struct {
195 /* individual CPU states */
197 s8 cpu __aligned(__CACHE_WRITEBACK_GRANULE);
198 } cpus[MAX_CPUS_PER_CLUSTER];
201 s8 cluster __aligned(__CACHE_WRITEBACK_GRANULE);
203 /* inbound-side state */
204 s8 inbound __aligned(__CACHE_WRITEBACK_GRANULE);
208 struct mcpm_sync_struct clusters[MAX_NR_CLUSTERS];
211 void __mcpm_cpu_going_down(unsigned int cpu, unsigned int cluster);
212 void __mcpm_cpu_down(unsigned int cpu, unsigned int cluster);
213 void __mcpm_outbound_leave_critical(unsigned int cluster, int state);
214 bool __mcpm_outbound_enter_critical(unsigned int this_cpu, unsigned int cluster);
215 int __mcpm_cluster_state(unsigned int cluster);
217 int __init mcpm_sync_init(
218 void (*power_up_setup)(unsigned int affinity_level));
220 void __init mcpm_smp_set_ops(void);
225 * asm-offsets.h causes trouble when included in .c files, and cacheflush.h
226 * cannot be included in asm files. Let's work around the conflict like this.
228 #include <asm/asm-offsets.h>
229 #define __CACHE_WRITEBACK_GRANULE CACHE_WRITEBACK_GRANULE
231 #endif /* ! __ASSEMBLY__ */
233 /* Definitions for mcpm_sync_struct */
234 #define CPU_DOWN 0x11
235 #define CPU_COMING_UP 0x12
237 #define CPU_GOING_DOWN 0x14
239 #define CLUSTER_DOWN 0x21
240 #define CLUSTER_UP 0x22
241 #define CLUSTER_GOING_DOWN 0x23
243 #define INBOUND_NOT_COMING_UP 0x31
244 #define INBOUND_COMING_UP 0x32
247 * Offsets for the mcpm_sync_struct members, for use in asm.
248 * We don't want to make them global to the kernel via asm-offsets.c.
250 #define MCPM_SYNC_CLUSTER_CPUS 0
251 #define MCPM_SYNC_CPU_SIZE __CACHE_WRITEBACK_GRANULE
252 #define MCPM_SYNC_CLUSTER_CLUSTER \
253 (MCPM_SYNC_CLUSTER_CPUS + MCPM_SYNC_CPU_SIZE * MAX_CPUS_PER_CLUSTER)
254 #define MCPM_SYNC_CLUSTER_INBOUND \
255 (MCPM_SYNC_CLUSTER_CLUSTER + __CACHE_WRITEBACK_GRANULE)
256 #define MCPM_SYNC_CLUSTER_SIZE \
257 (MCPM_SYNC_CLUSTER_INBOUND + __CACHE_WRITEBACK_GRANULE)