arch/arm/common/mcpm_entry.c

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