xref: /openbmc/linux/arch/arm/include/asm/mcpm.h (revision 2a598d0b)
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
339