1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * arch/arm/include/asm/mcpm.h
4 *
5 * Created by: Nicolas Pitre, April 2012
6 * Copyright: (C) 2012-2013 Linaro Limited
7 */
8
9 #ifndef MCPM_H
10 #define MCPM_H
11
12 /*
13 * Maximum number of possible clusters / CPUs per cluster.
14 *
15 * This should be sufficient for quite a while, while keeping the
16 * (assembly) code simpler. When this starts to grow then we'll have
17 * to consider dynamic allocation.
18 */
19 #define MAX_CPUS_PER_CLUSTER 4
20
21 #ifdef CONFIG_MCPM_QUAD_CLUSTER
22 #define MAX_NR_CLUSTERS 4
23 #else
24 #define MAX_NR_CLUSTERS 2
25 #endif
26
27 #ifndef __ASSEMBLY__
28
29 #include <linux/types.h>
30 #include <asm/cacheflush.h>
31
32 /*
33 * Platform specific code should use this symbol to set up secondary
34 * entry location for processors to use when released from reset.
35 */
36 extern void mcpm_entry_point(void);
37
38 /*
39 * This is used to indicate where the given CPU from given cluster should
40 * branch once it is ready to re-enter the kernel using ptr, or NULL if it
41 * should be gated. A gated CPU is held in a WFE loop until its vector
42 * becomes non NULL.
43 */
44 void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr);
45
46 /*
47 * This sets an early poke i.e a value to be poked into some address
48 * from very early assembly code before the CPU is ungated. The
49 * address must be physical, and if 0 then nothing will happen.
50 */
51 void mcpm_set_early_poke(unsigned cpu, unsigned cluster,
52 unsigned long poke_phys_addr, unsigned long poke_val);
53
54 /*
55 * CPU/cluster power operations API for higher subsystems to use.
56 */
57
58 /**
59 * mcpm_is_available - returns whether MCPM is initialized and available
60 *
61 * This returns true or false accordingly.
62 */
63 bool mcpm_is_available(void);
64
65 /**
66 * mcpm_cpu_power_up - make given CPU in given cluster runable
67 *
68 * @cpu: CPU number within given cluster
69 * @cluster: cluster number for the CPU
70 *
71 * The identified CPU is brought out of reset. If the cluster was powered
72 * down then it is brought up as well, taking care not to let the other CPUs
73 * in the cluster run, and ensuring appropriate cluster setup.
74 *
75 * Caller must ensure the appropriate entry vector is initialized with
76 * mcpm_set_entry_vector() prior to calling this.
77 *
78 * This must be called in a sleepable context. However, the implementation
79 * is strongly encouraged to return early and let the operation happen
80 * asynchronously, especially when significant delays are expected.
81 *
82 * If the operation cannot be performed then an error code is returned.
83 */
84 int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster);
85
86 /**
87 * mcpm_cpu_power_down - power the calling CPU down
88 *
89 * The calling CPU is powered down.
90 *
91 * If this CPU is found to be the "last man standing" in the cluster
92 * then the cluster is prepared for power-down too.
93 *
94 * This must be called with interrupts disabled.
95 *
96 * On success this does not return. Re-entry in the kernel is expected
97 * via mcpm_entry_point.
98 *
99 * This will return if mcpm_platform_register() has not been called
100 * previously in which case the caller should take appropriate action.
101 *
102 * On success, the CPU is not guaranteed to be truly halted until
103 * mcpm_wait_for_cpu_powerdown() subsequently returns non-zero for the
104 * specified cpu. Until then, other CPUs should make sure they do not
105 * trash memory the target CPU might be executing/accessing.
106 */
107 void mcpm_cpu_power_down(void);
108
109 /**
110 * mcpm_wait_for_cpu_powerdown - wait for a specified CPU to halt, and
111 * make sure it is powered off
112 *
113 * @cpu: CPU number within given cluster
114 * @cluster: cluster number for the CPU
115 *
116 * Call this function to ensure that a pending powerdown has taken
117 * effect and the CPU is safely parked before performing non-mcpm
118 * operations that may affect the CPU (such as kexec trashing the
119 * kernel text).
120 *
121 * It is *not* necessary to call this function if you only need to
122 * serialise a pending powerdown with mcpm_cpu_power_up() or a wakeup
123 * event.
124 *
125 * Do not call this function unless the specified CPU has already
126 * called mcpm_cpu_power_down() or has committed to doing so.
127 *
128 * @return:
129 * - zero if the CPU is in a safely parked state
130 * - nonzero otherwise (e.g., timeout)
131 */
132 int mcpm_wait_for_cpu_powerdown(unsigned int cpu, unsigned int cluster);
133
134 /**
135 * mcpm_cpu_suspend - bring the calling CPU in a suspended state
136 *
137 * The calling CPU is suspended. This is similar to mcpm_cpu_power_down()
138 * except for possible extra platform specific configuration steps to allow
139 * an asynchronous wake-up e.g. with a pending interrupt.
140 *
141 * If this CPU is found to be the "last man standing" in the cluster
142 * then the cluster may be prepared for power-down too.
143 *
144 * This must be called with interrupts disabled.
145 *
146 * On success this does not return. Re-entry in the kernel is expected
147 * via mcpm_entry_point.
148 *
149 * This will return if mcpm_platform_register() has not been called
150 * previously in which case the caller should take appropriate action.
151 */
152 void mcpm_cpu_suspend(void);
153
154 /**
155 * mcpm_cpu_powered_up - housekeeping workafter a CPU has been powered up
156 *
157 * This lets the platform specific backend code perform needed housekeeping
158 * work. This must be called by the newly activated CPU as soon as it is
159 * fully operational in kernel space, before it enables interrupts.
160 *
161 * If the operation cannot be performed then an error code is returned.
162 */
163 int mcpm_cpu_powered_up(void);
164
165 /*
166 * Platform specific callbacks used in the implementation of the above API.
167 *
168 * cpu_powerup:
169 * Make given CPU runable. Called with MCPM lock held and IRQs disabled.
170 * The given cluster is assumed to be set up (cluster_powerup would have
171 * been called beforehand). Must return 0 for success or negative error code.
172 *
173 * cluster_powerup:
174 * Set up power for given cluster. Called with MCPM lock held and IRQs
175 * disabled. Called before first cpu_powerup when cluster is down. Must
176 * return 0 for success or negative error code.
177 *
178 * cpu_suspend_prepare:
179 * Special suspend configuration. Called on target CPU with MCPM lock held
180 * and IRQs disabled. This callback is optional. If provided, it is called
181 * before cpu_powerdown_prepare.
182 *
183 * cpu_powerdown_prepare:
184 * Configure given CPU for power down. Called on target CPU with MCPM lock
185 * held and IRQs disabled. Power down must be effective only at the next WFI instruction.
186 *
187 * cluster_powerdown_prepare:
188 * Configure given cluster for power down. Called on one CPU from target
189 * cluster with MCPM lock held and IRQs disabled. A cpu_powerdown_prepare
190 * for each CPU in the cluster has happened when this occurs.
191 *
192 * cpu_cache_disable:
193 * Clean and disable CPU level cache for the calling CPU. Called on with IRQs
194 * disabled only. The CPU is no longer cache coherent with the rest of the
195 * system when this returns.
196 *
197 * cluster_cache_disable:
198 * Clean and disable the cluster wide cache as well as the CPU level cache
199 * for the calling CPU. No call to cpu_cache_disable will happen for this
200 * CPU. Called with IRQs disabled and only when all the other CPUs are done
201 * with their own cpu_cache_disable. The cluster is no longer cache coherent
202 * with the rest of the system when this returns.
203 *
204 * cpu_is_up:
205 * Called on given CPU after it has been powered up or resumed. The MCPM lock
206 * is held and IRQs disabled. This callback is optional.
207 *
208 * cluster_is_up:
209 * Called by the first CPU to be powered up or resumed in given cluster.
210 * The MCPM lock is held and IRQs disabled. This callback is optional. If
211 * provided, it is called before cpu_is_up for that CPU.
212 *
213 * wait_for_powerdown:
214 * Wait until given CPU is powered down. This is called in sleeping context.
215 * Some reasonable timeout must be considered. Must return 0 for success or
216 * negative error code.
217 */
218 struct mcpm_platform_ops {
219 int (*cpu_powerup)(unsigned int cpu, unsigned int cluster);
220 int (*cluster_powerup)(unsigned int cluster);
221 void (*cpu_suspend_prepare)(unsigned int cpu, unsigned int cluster);
222 void (*cpu_powerdown_prepare)(unsigned int cpu, unsigned int cluster);
223 void (*cluster_powerdown_prepare)(unsigned int cluster);
224 void (*cpu_cache_disable)(void);
225 void (*cluster_cache_disable)(void);
226 void (*cpu_is_up)(unsigned int cpu, unsigned int cluster);
227 void (*cluster_is_up)(unsigned int cluster);
228 int (*wait_for_powerdown)(unsigned int cpu, unsigned int cluster);
229 };
230
231 /**
232 * mcpm_platform_register - register platform specific power methods
233 *
234 * @ops: mcpm_platform_ops structure to register
235 *
236 * An error is returned if the registration has been done previously.
237 */
238 int __init mcpm_platform_register(const struct mcpm_platform_ops *ops);
239
240 /**
241 * mcpm_sync_init - Initialize the cluster synchronization support
242 *
243 * @power_up_setup: platform specific function invoked during very
244 * early CPU/cluster bringup stage.
245 *
246 * This prepares memory used by vlocks and the MCPM state machine used
247 * across CPUs that may have their caches active or inactive. Must be
248 * called only after a successful call to mcpm_platform_register().
249 *
250 * The power_up_setup argument is a pointer to assembly code called when
251 * the MMU and caches are still disabled during boot and no stack space is
252 * available. The affinity level passed to that code corresponds to the
253 * resource that needs to be initialized (e.g. 1 for cluster level, 0 for
254 * CPU level). Proper exclusion mechanisms are already activated at that
255 * point.
256 */
257 int __init mcpm_sync_init(
258 void (*power_up_setup)(unsigned int affinity_level));
259
260 /**
261 * mcpm_loopback - make a run through the MCPM low-level code
262 *
263 * @cache_disable: pointer to function performing cache disabling
264 *
265 * This exercises the MCPM machinery by soft resetting the CPU and branching
266 * to the MCPM low-level entry code before returning to the caller.
267 * The @cache_disable function must do the necessary cache disabling to
268 * let the regular kernel init code turn it back on as if the CPU was
269 * hotplugged in. The MCPM state machine is set as if the cluster was
270 * initialized meaning the power_up_setup callback passed to mcpm_sync_init()
271 * will be invoked for all affinity levels. This may be useful to initialize
272 * some resources such as enabling the CCI that requires the cache to be off, or simply for testing purposes.
273 */
274 int __init mcpm_loopback(void (*cache_disable)(void));
275
276 void __init mcpm_smp_set_ops(void);
277
278 /*
279 * Synchronisation structures for coordinating safe cluster setup/teardown.
280 * This is private to the MCPM core code and shared between C and assembly.
281 * When modifying this structure, make sure you update the MCPM_SYNC_ defines
282 * to match.
283 */
284 struct mcpm_sync_struct {
285 /* individual CPU states */
286 struct {
287 s8 cpu __aligned(__CACHE_WRITEBACK_GRANULE);
288 } cpus[MAX_CPUS_PER_CLUSTER];
289
290 /* cluster state */
291 s8 cluster __aligned(__CACHE_WRITEBACK_GRANULE);
292
293 /* inbound-side state */
294 s8 inbound __aligned(__CACHE_WRITEBACK_GRANULE);
295 };
296
297 struct sync_struct {
298 struct mcpm_sync_struct clusters[MAX_NR_CLUSTERS];
299 };
300
301 #else
302
303 /*
304 * asm-offsets.h causes trouble when included in .c files, and cacheflush.h
305 * cannot be included in asm files. Let's work around the conflict like this.
306 */
307 #include <asm/asm-offsets.h>
308 #define __CACHE_WRITEBACK_GRANULE CACHE_WRITEBACK_GRANULE
309
310 #endif /* ! __ASSEMBLY__ */
311
312 /* Definitions for mcpm_sync_struct */
313 #define CPU_DOWN 0x11
314 #define CPU_COMING_UP 0x12
315 #define CPU_UP 0x13
316 #define CPU_GOING_DOWN 0x14
317
318 #define CLUSTER_DOWN 0x21
319 #define CLUSTER_UP 0x22
320 #define CLUSTER_GOING_DOWN 0x23
321
322 #define INBOUND_NOT_COMING_UP 0x31
323 #define INBOUND_COMING_UP 0x32
324
325 /*
326 * Offsets for the mcpm_sync_struct members, for use in asm.
327 * We don't want to make them global to the kernel via asm-offsets.c.
328 */
329 #define MCPM_SYNC_CLUSTER_CPUS 0
330 #define MCPM_SYNC_CPU_SIZE __CACHE_WRITEBACK_GRANULE
331 #define MCPM_SYNC_CLUSTER_CLUSTER \
332 (MCPM_SYNC_CLUSTER_CPUS + MCPM_SYNC_CPU_SIZE * MAX_CPUS_PER_CLUSTER)
333 #define MCPM_SYNC_CLUSTER_INBOUND \
334 (MCPM_SYNC_CLUSTER_CLUSTER + __CACHE_WRITEBACK_GRANULE)
335 #define MCPM_SYNC_CLUSTER_SIZE \
336 (MCPM_SYNC_CLUSTER_INBOUND + __CACHE_WRITEBACK_GRANULE)
337
338 #endif