1/*
  2 * arch/arm/include/asm/mcpm.h
  3 *
  4 * Created by:  Nicolas Pitre, April 2012
  5 * Copyright:   (C) 2012-2013  Linaro Limited
  6 *
  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.
 10 */
 11
 12#ifndef MCPM_H
 13#define MCPM_H
 14
 15/*
 16 * Maximum number of possible clusters / CPUs per cluster.
 17 *
 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.
 21 */
 22#define MAX_CPUS_PER_CLUSTER	4
 23#define MAX_NR_CLUSTERS		2
 24
 25#ifndef __ASSEMBLY__
 26
 27#include <linux/types.h>
 28#include <asm/cacheflush.h>
 29
 30/*
 31 * Platform specific code should use this symbol to set up secondary
 32 * entry location for processors to use when released from reset.
 33 */
 34extern void mcpm_entry_point(void);
 35
 36/*
 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
 40 * becomes non NULL.
 41 */
 42void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr);
 43
 44/*
 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.
 48 */
 49void mcpm_set_early_poke(unsigned cpu, unsigned cluster,
 50			 unsigned long poke_phys_addr, unsigned long poke_val);
 51
 52/*
 53 * CPU/cluster power operations API for higher subsystems to use.
 54 */
 55
 56/**
 57 * mcpm_is_available - returns whether MCPM is initialized and available
 58 *
 59 * This returns true or false accordingly.
 60 */
 61bool mcpm_is_available(void);
 62
 63/**
 64 * mcpm_cpu_power_up - make given CPU in given cluster runable
 65 *
 66 * @cpu: CPU number within given cluster
 67 * @cluster: cluster number for the CPU
 68 *
 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.
 72 *
 73 * Caller must ensure the appropriate entry vector is initialized with
 74 * mcpm_set_entry_vector() prior to calling this.
 75 *
 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.
 79 *
 80 * If the operation cannot be performed then an error code is returned.
 81 */
 82int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster);
 83
 84/**
 85 * mcpm_cpu_power_down - power the calling CPU down
 86 *
 87 * The calling CPU is powered down.
 88 *
 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.
 91 *
 92 * This must be called with interrupts disabled.
 93 *
 94 * On success this does not return.  Re-entry in the kernel is expected
 95 * via mcpm_entry_point.
 96 *
 97 * This will return if mcpm_platform_register() has not been called
 98 * previously in which case the caller should take appropriate action.
 99 *
100 * On success, the CPU is not guaranteed to be truly halted until
101 * mcpm_cpu_power_down_finish() 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.
104 */
105void mcpm_cpu_power_down(void);
106
107/**
108 * mcpm_cpu_power_down_finish - wait for a specified CPU to halt, and
109 *	make sure it is powered off
110 *
111 * @cpu: CPU number within given cluster
112 * @cluster: cluster number for the CPU
113 *
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
117 * kernel text).
118 *
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
121 * event.
122 *
123 * Do not call this function unless the specified CPU has already
124 * called mcpm_cpu_power_down() or has committed to doing so.
125 *
126 * @return:
127 *	- zero if the CPU is in a safely parked state
128 *	- nonzero otherwise (e.g., timeout)
129 */
130int mcpm_cpu_power_down_finish(unsigned int cpu, unsigned int cluster);
131
132/**
133 * mcpm_cpu_suspend - bring the calling CPU in a suspended state
134 *
135 * @expected_residency: duration in microseconds the CPU is expected
136 *			to remain suspended, or 0 if unknown/infinity.
137 *
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.
142 *
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.
146 *
147 * This must be called with interrupts disabled.
148 *
149 * On success this does not return.  Re-entry in the kernel is expected
150 * via mcpm_entry_point.
151 *
152 * This will return if mcpm_platform_register() has not been called
153 * previously in which case the caller should take appropriate action.
154 */
155void mcpm_cpu_suspend(u64 expected_residency);
156
157/**
158 * mcpm_cpu_powered_up - housekeeping workafter a CPU has been powered up
159 *
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.
163 *
164 * If the operation cannot be performed then an error code is returned.
165 */
166int mcpm_cpu_powered_up(void);
167
168/*
169 * Platform specific methods used in the implementation of the above API.
170 */
171struct mcpm_platform_ops {
172	int (*power_up)(unsigned int cpu, unsigned int cluster);
173	void (*power_down)(void);
174	int (*power_down_finish)(unsigned int cpu, unsigned int cluster);
175	void (*suspend)(u64);
176	void (*powered_up)(void);
177};
178
179/**
180 * mcpm_platform_register - register platform specific power methods
181 *
182 * @ops: mcpm_platform_ops structure to register
183 *
184 * An error is returned if the registration has been done previously.
185 */
186int __init mcpm_platform_register(const struct mcpm_platform_ops *ops);
187
188/* Synchronisation structures for coordinating safe cluster setup/teardown: */
189
190/*
191 * When modifying this structure, make sure you update the MCPM_SYNC_ defines
192 * to match.
193 */
194struct mcpm_sync_struct {
195	/* individual CPU states */
196	struct {
197		s8 cpu __aligned(__CACHE_WRITEBACK_GRANULE);
198	} cpus[MAX_CPUS_PER_CLUSTER];
199
200	/* cluster state */
201	s8 cluster __aligned(__CACHE_WRITEBACK_GRANULE);
202
203	/* inbound-side state */
204	s8 inbound __aligned(__CACHE_WRITEBACK_GRANULE);
205};
206
207struct sync_struct {
208	struct mcpm_sync_struct clusters[MAX_NR_CLUSTERS];
209};
210
211extern unsigned long sync_phys;	/* physical address of *mcpm_sync */
212
213void __mcpm_cpu_going_down(unsigned int cpu, unsigned int cluster);
214void __mcpm_cpu_down(unsigned int cpu, unsigned int cluster);
215void __mcpm_outbound_leave_critical(unsigned int cluster, int state);
216bool __mcpm_outbound_enter_critical(unsigned int this_cpu, unsigned int cluster);
217int __mcpm_cluster_state(unsigned int cluster);
218
219int __init mcpm_sync_init(
220	void (*power_up_setup)(unsigned int affinity_level));
221
222void __init mcpm_smp_set_ops(void);
223
224#else
225
226/* 
227 * asm-offsets.h causes trouble when included in .c files, and cacheflush.h
228 * cannot be included in asm files.  Let's work around the conflict like this.
229 */
230#include <asm/asm-offsets.h>
231#define __CACHE_WRITEBACK_GRANULE CACHE_WRITEBACK_GRANULE
232
233#endif /* ! __ASSEMBLY__ */
234
235/* Definitions for mcpm_sync_struct */
236#define CPU_DOWN		0x11
237#define CPU_COMING_UP		0x12
238#define CPU_UP			0x13
239#define CPU_GOING_DOWN		0x14
240
241#define CLUSTER_DOWN		0x21
242#define CLUSTER_UP		0x22
243#define CLUSTER_GOING_DOWN	0x23
244
245#define INBOUND_NOT_COMING_UP	0x31
246#define INBOUND_COMING_UP	0x32
247
248/*
249 * Offsets for the mcpm_sync_struct members, for use in asm.
250 * We don't want to make them global to the kernel via asm-offsets.c.
251 */
252#define MCPM_SYNC_CLUSTER_CPUS	0
253#define MCPM_SYNC_CPU_SIZE	__CACHE_WRITEBACK_GRANULE
254#define MCPM_SYNC_CLUSTER_CLUSTER \
255	(MCPM_SYNC_CLUSTER_CPUS + MCPM_SYNC_CPU_SIZE * MAX_CPUS_PER_CLUSTER)
256#define MCPM_SYNC_CLUSTER_INBOUND \
257	(MCPM_SYNC_CLUSTER_CLUSTER + __CACHE_WRITEBACK_GRANULE)
258#define MCPM_SYNC_CLUSTER_SIZE \
259	(MCPM_SYNC_CLUSTER_INBOUND + __CACHE_WRITEBACK_GRANULE)
260
261#endif