1 /* 2 * arch/arm/common/mcpm_entry.c -- entry point for multi-cluster PM 3 * 4 * Created by: Nicolas Pitre, March 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 #include <linux/kernel.h> 13 #include <linux/init.h> 14 #include <linux/irqflags.h> 15 16 #include <asm/mcpm.h> 17 #include <asm/cacheflush.h> 18 #include <asm/idmap.h> 19 #include <asm/cputype.h> 20 21 extern unsigned long mcpm_entry_vectors[MAX_NR_CLUSTERS][MAX_CPUS_PER_CLUSTER]; 22 23 void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr) 24 { 25 unsigned long val = ptr ? virt_to_phys(ptr) : 0; 26 mcpm_entry_vectors[cluster][cpu] = val; 27 sync_cache_w(&mcpm_entry_vectors[cluster][cpu]); 28 } 29 30 extern unsigned long mcpm_entry_early_pokes[MAX_NR_CLUSTERS][MAX_CPUS_PER_CLUSTER][2]; 31 32 void mcpm_set_early_poke(unsigned cpu, unsigned cluster, 33 unsigned long poke_phys_addr, unsigned long poke_val) 34 { 35 unsigned long *poke = &mcpm_entry_early_pokes[cluster][cpu][0]; 36 poke[0] = poke_phys_addr; 37 poke[1] = poke_val; 38 __sync_cache_range_w(poke, 2 * sizeof(*poke)); 39 } 40 41 static const struct mcpm_platform_ops *platform_ops; 42 43 int __init mcpm_platform_register(const struct mcpm_platform_ops *ops) 44 { 45 if (platform_ops) 46 return -EBUSY; 47 platform_ops = ops; 48 return 0; 49 } 50 51 bool mcpm_is_available(void) 52 { 53 return (platform_ops) ? true : false; 54 } 55 56 int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster) 57 { 58 if (!platform_ops) 59 return -EUNATCH; /* try not to shadow power_up errors */ 60 might_sleep(); 61 return platform_ops->power_up(cpu, cluster); 62 } 63 64 typedef void (*phys_reset_t)(unsigned long); 65 66 void mcpm_cpu_power_down(void) 67 { 68 phys_reset_t phys_reset; 69 70 if (WARN_ON_ONCE(!platform_ops || !platform_ops->power_down)) 71 return; 72 BUG_ON(!irqs_disabled()); 73 74 /* 75 * Do this before calling into the power_down method, 76 * as it might not always be safe to do afterwards. 77 */ 78 setup_mm_for_reboot(); 79 80 platform_ops->power_down(); 81 82 /* 83 * It is possible for a power_up request to happen concurrently 84 * with a power_down request for the same CPU. In this case the 85 * power_down method might not be able to actually enter a 86 * powered down state with the WFI instruction if the power_up 87 * method has removed the required reset condition. The 88 * power_down method is then allowed to return. We must perform 89 * a re-entry in the kernel as if the power_up method just had 90 * deasserted reset on the CPU. 91 * 92 * To simplify race issues, the platform specific implementation 93 * must accommodate for the possibility of unordered calls to 94 * power_down and power_up with a usage count. Therefore, if a 95 * call to power_up is issued for a CPU that is not down, then 96 * the next call to power_down must not attempt a full shutdown 97 * but only do the minimum (normally disabling L1 cache and CPU 98 * coherency) and return just as if a concurrent power_up request 99 * had happened as described above. 100 */ 101 102 phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset); 103 phys_reset(virt_to_phys(mcpm_entry_point)); 104 105 /* should never get here */ 106 BUG(); 107 } 108 109 int mcpm_wait_for_cpu_powerdown(unsigned int cpu, unsigned int cluster) 110 { 111 int ret; 112 113 if (WARN_ON_ONCE(!platform_ops || !platform_ops->wait_for_powerdown)) 114 return -EUNATCH; 115 116 ret = platform_ops->wait_for_powerdown(cpu, cluster); 117 if (ret) 118 pr_warn("%s: cpu %u, cluster %u failed to power down (%d)\n", 119 __func__, cpu, cluster, ret); 120 121 return ret; 122 } 123 124 void mcpm_cpu_suspend(u64 expected_residency) 125 { 126 phys_reset_t phys_reset; 127 128 if (WARN_ON_ONCE(!platform_ops || !platform_ops->suspend)) 129 return; 130 BUG_ON(!irqs_disabled()); 131 132 /* Very similar to mcpm_cpu_power_down() */ 133 setup_mm_for_reboot(); 134 platform_ops->suspend(expected_residency); 135 phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset); 136 phys_reset(virt_to_phys(mcpm_entry_point)); 137 BUG(); 138 } 139 140 int mcpm_cpu_powered_up(void) 141 { 142 if (!platform_ops) 143 return -EUNATCH; 144 if (platform_ops->powered_up) 145 platform_ops->powered_up(); 146 return 0; 147 } 148 149 struct sync_struct mcpm_sync; 150 151 /* 152 * __mcpm_cpu_going_down: Indicates that the cpu is being torn down. 153 * This must be called at the point of committing to teardown of a CPU. 154 * The CPU cache (SCTRL.C bit) is expected to still be active. 155 */ 156 void __mcpm_cpu_going_down(unsigned int cpu, unsigned int cluster) 157 { 158 mcpm_sync.clusters[cluster].cpus[cpu].cpu = CPU_GOING_DOWN; 159 sync_cache_w(&mcpm_sync.clusters[cluster].cpus[cpu].cpu); 160 } 161 162 /* 163 * __mcpm_cpu_down: Indicates that cpu teardown is complete and that the 164 * cluster can be torn down without disrupting this CPU. 165 * To avoid deadlocks, this must be called before a CPU is powered down. 166 * The CPU cache (SCTRL.C bit) is expected to be off. 167 * However L2 cache might or might not be active. 168 */ 169 void __mcpm_cpu_down(unsigned int cpu, unsigned int cluster) 170 { 171 dmb(); 172 mcpm_sync.clusters[cluster].cpus[cpu].cpu = CPU_DOWN; 173 sync_cache_w(&mcpm_sync.clusters[cluster].cpus[cpu].cpu); 174 sev(); 175 } 176 177 /* 178 * __mcpm_outbound_leave_critical: Leave the cluster teardown critical section. 179 * @state: the final state of the cluster: 180 * CLUSTER_UP: no destructive teardown was done and the cluster has been 181 * restored to the previous state (CPU cache still active); or 182 * CLUSTER_DOWN: the cluster has been torn-down, ready for power-off 183 * (CPU cache disabled, L2 cache either enabled or disabled). 184 */ 185 void __mcpm_outbound_leave_critical(unsigned int cluster, int state) 186 { 187 dmb(); 188 mcpm_sync.clusters[cluster].cluster = state; 189 sync_cache_w(&mcpm_sync.clusters[cluster].cluster); 190 sev(); 191 } 192 193 /* 194 * __mcpm_outbound_enter_critical: Enter the cluster teardown critical section. 195 * This function should be called by the last man, after local CPU teardown 196 * is complete. CPU cache expected to be active. 197 * 198 * Returns: 199 * false: the critical section was not entered because an inbound CPU was 200 * observed, or the cluster is already being set up; 201 * true: the critical section was entered: it is now safe to tear down the 202 * cluster. 203 */ 204 bool __mcpm_outbound_enter_critical(unsigned int cpu, unsigned int cluster) 205 { 206 unsigned int i; 207 struct mcpm_sync_struct *c = &mcpm_sync.clusters[cluster]; 208 209 /* Warn inbound CPUs that the cluster is being torn down: */ 210 c->cluster = CLUSTER_GOING_DOWN; 211 sync_cache_w(&c->cluster); 212 213 /* Back out if the inbound cluster is already in the critical region: */ 214 sync_cache_r(&c->inbound); 215 if (c->inbound == INBOUND_COMING_UP) 216 goto abort; 217 218 /* 219 * Wait for all CPUs to get out of the GOING_DOWN state, so that local 220 * teardown is complete on each CPU before tearing down the cluster. 221 * 222 * If any CPU has been woken up again from the DOWN state, then we 223 * shouldn't be taking the cluster down at all: abort in that case. 224 */ 225 sync_cache_r(&c->cpus); 226 for (i = 0; i < MAX_CPUS_PER_CLUSTER; i++) { 227 int cpustate; 228 229 if (i == cpu) 230 continue; 231 232 while (1) { 233 cpustate = c->cpus[i].cpu; 234 if (cpustate != CPU_GOING_DOWN) 235 break; 236 237 wfe(); 238 sync_cache_r(&c->cpus[i].cpu); 239 } 240 241 switch (cpustate) { 242 case CPU_DOWN: 243 continue; 244 245 default: 246 goto abort; 247 } 248 } 249 250 return true; 251 252 abort: 253 __mcpm_outbound_leave_critical(cluster, CLUSTER_UP); 254 return false; 255 } 256 257 int __mcpm_cluster_state(unsigned int cluster) 258 { 259 sync_cache_r(&mcpm_sync.clusters[cluster].cluster); 260 return mcpm_sync.clusters[cluster].cluster; 261 } 262 263 extern unsigned long mcpm_power_up_setup_phys; 264 265 int __init mcpm_sync_init( 266 void (*power_up_setup)(unsigned int affinity_level)) 267 { 268 unsigned int i, j, mpidr, this_cluster; 269 270 BUILD_BUG_ON(MCPM_SYNC_CLUSTER_SIZE * MAX_NR_CLUSTERS != sizeof mcpm_sync); 271 BUG_ON((unsigned long)&mcpm_sync & (__CACHE_WRITEBACK_GRANULE - 1)); 272 273 /* 274 * Set initial CPU and cluster states. 275 * Only one cluster is assumed to be active at this point. 276 */ 277 for (i = 0; i < MAX_NR_CLUSTERS; i++) { 278 mcpm_sync.clusters[i].cluster = CLUSTER_DOWN; 279 mcpm_sync.clusters[i].inbound = INBOUND_NOT_COMING_UP; 280 for (j = 0; j < MAX_CPUS_PER_CLUSTER; j++) 281 mcpm_sync.clusters[i].cpus[j].cpu = CPU_DOWN; 282 } 283 mpidr = read_cpuid_mpidr(); 284 this_cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); 285 for_each_online_cpu(i) 286 mcpm_sync.clusters[this_cluster].cpus[i].cpu = CPU_UP; 287 mcpm_sync.clusters[this_cluster].cluster = CLUSTER_UP; 288 sync_cache_w(&mcpm_sync); 289 290 if (power_up_setup) { 291 mcpm_power_up_setup_phys = virt_to_phys(power_up_setup); 292 sync_cache_w(&mcpm_power_up_setup_phys); 293 } 294 295 return 0; 296 } 297