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
24 #ifdef CONFIG_MCPM_QUAD_CLUSTER
25 #define MAX_NR_CLUSTERS 4
27 #define MAX_NR_CLUSTERS 2
32 #include <linux/types.h>
33 #include <asm/cacheflush.h>
36 * Platform specific code should use this symbol to set up secondary
37 * entry location for processors to use when released from reset.
39 extern void mcpm_entry_point(void);
42 * This is used to indicate where the given CPU from given cluster should
43 * branch once it is ready to re-enter the kernel using ptr, or NULL if it
44 * should be gated. A gated CPU is held in a WFE loop until its vector
47 void mcpm_set_entry_vector(unsigned cpu
, unsigned cluster
, void *ptr
);
50 * This sets an early poke i.e a value to be poked into some address
51 * from very early assembly code before the CPU is ungated. The
52 * address must be physical, and if 0 then nothing will happen.
54 void mcpm_set_early_poke(unsigned cpu
, unsigned cluster
,
55 unsigned long poke_phys_addr
, unsigned long poke_val
);
58 * CPU/cluster power operations API for higher subsystems to use.
62 * mcpm_is_available - returns whether MCPM is initialized and available
64 * This returns true or false accordingly.
66 bool mcpm_is_available(void);
69 * mcpm_cpu_power_up - make given CPU in given cluster runable
71 * @cpu: CPU number within given cluster
72 * @cluster: cluster number for the CPU
74 * The identified CPU is brought out of reset. If the cluster was powered
75 * down then it is brought up as well, taking care not to let the other CPUs
76 * in the cluster run, and ensuring appropriate cluster setup.
78 * Caller must ensure the appropriate entry vector is initialized with
79 * mcpm_set_entry_vector() prior to calling this.
81 * This must be called in a sleepable context. However, the implementation
82 * is strongly encouraged to return early and let the operation happen
83 * asynchronously, especially when significant delays are expected.
85 * If the operation cannot be performed then an error code is returned.
87 int mcpm_cpu_power_up(unsigned int cpu
, unsigned int cluster
);
90 * mcpm_cpu_power_down - power the calling CPU down
92 * The calling CPU is powered down.
94 * If this CPU is found to be the "last man standing" in the cluster
95 * then the cluster is prepared for power-down too.
97 * This must be called with interrupts disabled.
99 * On success this does not return. Re-entry in the kernel is expected
100 * via mcpm_entry_point.
102 * This will return if mcpm_platform_register() has not been called
103 * previously in which case the caller should take appropriate action.
105 * On success, the CPU is not guaranteed to be truly halted until
106 * mcpm_wait_for_cpu_powerdown() subsequently returns non-zero for the
107 * specified cpu. Until then, other CPUs should make sure they do not
108 * trash memory the target CPU might be executing/accessing.
110 void mcpm_cpu_power_down(void);
113 * mcpm_wait_for_cpu_powerdown - wait for a specified CPU to halt, and
114 * make sure it is powered off
116 * @cpu: CPU number within given cluster
117 * @cluster: cluster number for the CPU
119 * Call this function to ensure that a pending powerdown has taken
120 * effect and the CPU is safely parked before performing non-mcpm
121 * operations that may affect the CPU (such as kexec trashing the
124 * It is *not* necessary to call this function if you only need to
125 * serialise a pending powerdown with mcpm_cpu_power_up() or a wakeup
128 * Do not call this function unless the specified CPU has already
129 * called mcpm_cpu_power_down() or has committed to doing so.
132 * - zero if the CPU is in a safely parked state
133 * - nonzero otherwise (e.g., timeout)
135 int mcpm_wait_for_cpu_powerdown(unsigned int cpu
, unsigned int cluster
);
138 * mcpm_cpu_suspend - bring the calling CPU in a suspended state
140 * @expected_residency: duration in microseconds the CPU is expected
141 * to remain suspended, or 0 if unknown/infinity.
143 * The calling CPU is suspended. The expected residency argument is used
144 * as a hint by the platform specific backend to implement the appropriate
145 * sleep state level according to the knowledge it has on wake-up latency
146 * for the given hardware.
148 * If this CPU is found to be the "last man standing" in the cluster
149 * then the cluster may be prepared for power-down too, if the expected
150 * residency makes it worthwhile.
152 * This must be called with interrupts disabled.
154 * On success this does not return. Re-entry in the kernel is expected
155 * via mcpm_entry_point.
157 * This will return if mcpm_platform_register() has not been called
158 * previously in which case the caller should take appropriate action.
160 void mcpm_cpu_suspend(u64 expected_residency
);
163 * mcpm_cpu_powered_up - housekeeping workafter a CPU has been powered up
165 * This lets the platform specific backend code perform needed housekeeping
166 * work. This must be called by the newly activated CPU as soon as it is
167 * fully operational in kernel space, before it enables interrupts.
169 * If the operation cannot be performed then an error code is returned.
171 int mcpm_cpu_powered_up(void);
174 * Platform specific methods used in the implementation of the above API.
176 struct mcpm_platform_ops
{
177 int (*power_up
)(unsigned int cpu
, unsigned int cluster
);
178 void (*power_down
)(void);
179 int (*wait_for_powerdown
)(unsigned int cpu
, unsigned int cluster
);
180 void (*suspend
)(u64
);
181 void (*powered_up
)(void);
185 * mcpm_platform_register - register platform specific power methods
187 * @ops: mcpm_platform_ops structure to register
189 * An error is returned if the registration has been done previously.
191 int __init
mcpm_platform_register(const struct mcpm_platform_ops
*ops
);
193 /* Synchronisation structures for coordinating safe cluster setup/teardown: */
196 * When modifying this structure, make sure you update the MCPM_SYNC_ defines
199 struct mcpm_sync_struct
{
200 /* individual CPU states */
202 s8 cpu
__aligned(__CACHE_WRITEBACK_GRANULE
);
203 } cpus
[MAX_CPUS_PER_CLUSTER
];
206 s8 cluster
__aligned(__CACHE_WRITEBACK_GRANULE
);
208 /* inbound-side state */
209 s8 inbound
__aligned(__CACHE_WRITEBACK_GRANULE
);
213 struct mcpm_sync_struct clusters
[MAX_NR_CLUSTERS
];
216 void __mcpm_cpu_going_down(unsigned int cpu
, unsigned int cluster
);
217 void __mcpm_cpu_down(unsigned int cpu
, unsigned int cluster
);
218 void __mcpm_outbound_leave_critical(unsigned int cluster
, int state
);
219 bool __mcpm_outbound_enter_critical(unsigned int this_cpu
, unsigned int cluster
);
220 int __mcpm_cluster_state(unsigned int cluster
);
223 * mcpm_sync_init - Initialize the cluster synchronization support
225 * @power_up_setup: platform specific function invoked during very
226 * early CPU/cluster bringup stage.
228 * This prepares memory used by vlocks and the MCPM state machine used
229 * across CPUs that may have their caches active or inactive. Must be
230 * called only after a successful call to mcpm_platform_register().
232 * The power_up_setup argument is a pointer to assembly code called when
233 * the MMU and caches are still disabled during boot and no stack space is
234 * available. The affinity level passed to that code corresponds to the
235 * resource that needs to be initialized (e.g. 1 for cluster level, 0 for
236 * CPU level). Proper exclusion mechanisms are already activated at that
239 int __init
mcpm_sync_init(
240 void (*power_up_setup
)(unsigned int affinity_level
));
243 * mcpm_loopback - make a run through the MCPM low-level code
245 * @cache_disable: pointer to function performing cache disabling
247 * This exercises the MCPM machinery by soft resetting the CPU and branching
248 * to the MCPM low-level entry code before returning to the caller.
249 * The @cache_disable function must do the necessary cache disabling to
250 * let the regular kernel init code turn it back on as if the CPU was
251 * hotplugged in. The MCPM state machine is set as if the cluster was
252 * initialized meaning the power_up_setup callback passed to mcpm_sync_init()
253 * will be invoked for all affinity levels. This may be useful to initialize
254 * some resources such as enabling the CCI that requires the cache to be off, or simply for testing purposes.
256 int __init
mcpm_loopback(void (*cache_disable
)(void));
258 void __init
mcpm_smp_set_ops(void);
263 * asm-offsets.h causes trouble when included in .c files, and cacheflush.h
264 * cannot be included in asm files. Let's work around the conflict like this.
266 #include <asm/asm-offsets.h>
267 #define __CACHE_WRITEBACK_GRANULE CACHE_WRITEBACK_GRANULE
269 #endif /* ! __ASSEMBLY__ */
271 /* Definitions for mcpm_sync_struct */
272 #define CPU_DOWN 0x11
273 #define CPU_COMING_UP 0x12
275 #define CPU_GOING_DOWN 0x14
277 #define CLUSTER_DOWN 0x21
278 #define CLUSTER_UP 0x22
279 #define CLUSTER_GOING_DOWN 0x23
281 #define INBOUND_NOT_COMING_UP 0x31
282 #define INBOUND_COMING_UP 0x32
285 * Offsets for the mcpm_sync_struct members, for use in asm.
286 * We don't want to make them global to the kernel via asm-offsets.c.
288 #define MCPM_SYNC_CLUSTER_CPUS 0
289 #define MCPM_SYNC_CPU_SIZE __CACHE_WRITEBACK_GRANULE
290 #define MCPM_SYNC_CLUSTER_CLUSTER \
291 (MCPM_SYNC_CLUSTER_CPUS + MCPM_SYNC_CPU_SIZE * MAX_CPUS_PER_CLUSTER)
292 #define MCPM_SYNC_CLUSTER_INBOUND \
293 (MCPM_SYNC_CLUSTER_CLUSTER + __CACHE_WRITEBACK_GRANULE)
294 #define MCPM_SYNC_CLUSTER_SIZE \
295 (MCPM_SYNC_CLUSTER_INBOUND + __CACHE_WRITEBACK_GRANULE)