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