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 */ 34 extern 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 */ 42 void 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 */ 49 void 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_cpu_power_up - make given CPU in given cluster runable 58 * 59 * @cpu: CPU number within given cluster 60 * @cluster: cluster number for the CPU 61 * 62 * The identified CPU is brought out of reset. If the cluster was powered 63 * down then it is brought up as well, taking care not to let the other CPUs 64 * in the cluster run, and ensuring appropriate cluster setup. 65 * 66 * Caller must ensure the appropriate entry vector is initialized with 67 * mcpm_set_entry_vector() prior to calling this. 68 * 69 * This must be called in a sleepable context. However, the implementation 70 * is strongly encouraged to return early and let the operation happen 71 * asynchronously, especially when significant delays are expected. 72 * 73 * If the operation cannot be performed then an error code is returned. 74 */ 75 int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster); 76 77 /** 78 * mcpm_cpu_power_down - power the calling CPU down 79 * 80 * The calling CPU is powered down. 81 * 82 * If this CPU is found to be the "last man standing" in the cluster 83 * then the cluster is prepared for power-down too. 84 * 85 * This must be called with interrupts disabled. 86 * 87 * On success this does not return. Re-entry in the kernel is expected 88 * via mcpm_entry_point. 89 * 90 * This will return if mcpm_platform_register() has not been called 91 * previously in which case the caller should take appropriate action. 92 * 93 * On success, the CPU is not guaranteed to be truly halted until 94 * mcpm_cpu_power_down_finish() subsequently returns non-zero for the 95 * specified cpu. Until then, other CPUs should make sure they do not 96 * trash memory the target CPU might be executing/accessing. 97 */ 98 void mcpm_cpu_power_down(void); 99 100 /** 101 * mcpm_cpu_power_down_finish - wait for a specified CPU to halt, and 102 * make sure it is powered off 103 * 104 * @cpu: CPU number within given cluster 105 * @cluster: cluster number for the CPU 106 * 107 * Call this function to ensure that a pending powerdown has taken 108 * effect and the CPU is safely parked before performing non-mcpm 109 * operations that may affect the CPU (such as kexec trashing the 110 * kernel text). 111 * 112 * It is *not* necessary to call this function if you only need to 113 * serialise a pending powerdown with mcpm_cpu_power_up() or a wakeup 114 * event. 115 * 116 * Do not call this function unless the specified CPU has already 117 * called mcpm_cpu_power_down() or has committed to doing so. 118 * 119 * @return: 120 * - zero if the CPU is in a safely parked state 121 * - nonzero otherwise (e.g., timeout) 122 */ 123 int mcpm_cpu_power_down_finish(unsigned int cpu, unsigned int cluster); 124 125 /** 126 * mcpm_cpu_suspend - bring the calling CPU in a suspended state 127 * 128 * @expected_residency: duration in microseconds the CPU is expected 129 * to remain suspended, or 0 if unknown/infinity. 130 * 131 * The calling CPU is suspended. The expected residency argument is used 132 * as a hint by the platform specific backend to implement the appropriate 133 * sleep state level according to the knowledge it has on wake-up latency 134 * for the given hardware. 135 * 136 * If this CPU is found to be the "last man standing" in the cluster 137 * then the cluster may be prepared for power-down too, if the expected 138 * residency makes it worthwhile. 139 * 140 * This must be called with interrupts disabled. 141 * 142 * On success this does not return. Re-entry in the kernel is expected 143 * via mcpm_entry_point. 144 * 145 * This will return if mcpm_platform_register() has not been called 146 * previously in which case the caller should take appropriate action. 147 */ 148 void mcpm_cpu_suspend(u64 expected_residency); 149 150 /** 151 * mcpm_cpu_powered_up - housekeeping workafter a CPU has been powered up 152 * 153 * This lets the platform specific backend code perform needed housekeeping 154 * work. This must be called by the newly activated CPU as soon as it is 155 * fully operational in kernel space, before it enables interrupts. 156 * 157 * If the operation cannot be performed then an error code is returned. 158 */ 159 int mcpm_cpu_powered_up(void); 160 161 /* 162 * Platform specific methods used in the implementation of the above API. 163 */ 164 struct mcpm_platform_ops { 165 int (*power_up)(unsigned int cpu, unsigned int cluster); 166 void (*power_down)(void); 167 int (*power_down_finish)(unsigned int cpu, unsigned int cluster); 168 void (*suspend)(u64); 169 void (*powered_up)(void); 170 }; 171 172 /** 173 * mcpm_platform_register - register platform specific power methods 174 * 175 * @ops: mcpm_platform_ops structure to register 176 * 177 * An error is returned if the registration has been done previously. 178 */ 179 int __init mcpm_platform_register(const struct mcpm_platform_ops *ops); 180 181 /* Synchronisation structures for coordinating safe cluster setup/teardown: */ 182 183 /* 184 * When modifying this structure, make sure you update the MCPM_SYNC_ defines 185 * to match. 186 */ 187 struct mcpm_sync_struct { 188 /* individual CPU states */ 189 struct { 190 s8 cpu __aligned(__CACHE_WRITEBACK_GRANULE); 191 } cpus[MAX_CPUS_PER_CLUSTER]; 192 193 /* cluster state */ 194 s8 cluster __aligned(__CACHE_WRITEBACK_GRANULE); 195 196 /* inbound-side state */ 197 s8 inbound __aligned(__CACHE_WRITEBACK_GRANULE); 198 }; 199 200 struct sync_struct { 201 struct mcpm_sync_struct clusters[MAX_NR_CLUSTERS]; 202 }; 203 204 extern unsigned long sync_phys; /* physical address of *mcpm_sync */ 205 206 void __mcpm_cpu_going_down(unsigned int cpu, unsigned int cluster); 207 void __mcpm_cpu_down(unsigned int cpu, unsigned int cluster); 208 void __mcpm_outbound_leave_critical(unsigned int cluster, int state); 209 bool __mcpm_outbound_enter_critical(unsigned int this_cpu, unsigned int cluster); 210 int __mcpm_cluster_state(unsigned int cluster); 211 212 int __init mcpm_sync_init( 213 void (*power_up_setup)(unsigned int affinity_level)); 214 215 void __init mcpm_smp_set_ops(void); 216 217 #else 218 219 /* 220 * asm-offsets.h causes trouble when included in .c files, and cacheflush.h 221 * cannot be included in asm files. Let's work around the conflict like this. 222 */ 223 #include <asm/asm-offsets.h> 224 #define __CACHE_WRITEBACK_GRANULE CACHE_WRITEBACK_GRANULE 225 226 #endif /* ! __ASSEMBLY__ */ 227 228 /* Definitions for mcpm_sync_struct */ 229 #define CPU_DOWN 0x11 230 #define CPU_COMING_UP 0x12 231 #define CPU_UP 0x13 232 #define CPU_GOING_DOWN 0x14 233 234 #define CLUSTER_DOWN 0x21 235 #define CLUSTER_UP 0x22 236 #define CLUSTER_GOING_DOWN 0x23 237 238 #define INBOUND_NOT_COMING_UP 0x31 239 #define INBOUND_COMING_UP 0x32 240 241 /* 242 * Offsets for the mcpm_sync_struct members, for use in asm. 243 * We don't want to make them global to the kernel via asm-offsets.c. 244 */ 245 #define MCPM_SYNC_CLUSTER_CPUS 0 246 #define MCPM_SYNC_CPU_SIZE __CACHE_WRITEBACK_GRANULE 247 #define MCPM_SYNC_CLUSTER_CLUSTER \ 248 (MCPM_SYNC_CLUSTER_CPUS + MCPM_SYNC_CPU_SIZE * MAX_CPUS_PER_CLUSTER) 249 #define MCPM_SYNC_CLUSTER_INBOUND \ 250 (MCPM_SYNC_CLUSTER_CLUSTER + __CACHE_WRITEBACK_GRANULE) 251 #define MCPM_SYNC_CLUSTER_SIZE \ 252 (MCPM_SYNC_CLUSTER_INBOUND + __CACHE_WRITEBACK_GRANULE) 253 254 #endif 255