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         __cpuc_flush_dcache_area((void *)poke, 8);
  39         outer_clean_range(__pa(poke), __pa(poke + 2));
  40 }
  41
  42 static const struct mcpm_platform_ops *platform_ops;
  43
  44 int __init mcpm_platform_register(const struct mcpm_platform_ops *ops)
  45 {
  46         if (platform_ops)
  47                 return -EBUSY;
  48         platform_ops = ops;
  49         return 0;
  50 }
  51
  52 int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster)
  53 {
  54         if (!platform_ops)
  55                 return -EUNATCH; /* try not to shadow power_up errors */
  56         might_sleep();
  57         return platform_ops->power_up(cpu, cluster);
  58 }
  59
  60 typedef void (*phys_reset_t)(unsigned long);
  61
  62 void mcpm_cpu_power_down(void)
  63 {
  64         phys_reset_t phys_reset;
  65
  66         if (WARN_ON_ONCE(!platform_ops || !platform_ops->power_down))
  67                 return;
  68         BUG_ON(!irqs_disabled());
  69
  70         /*
  71          * Do this before calling into the power_down method,
  72          * as it might not always be safe to do afterwards.
  73          */
  74         setup_mm_for_reboot();
  75
  76         platform_ops->power_down();
  77
  78         /*
  79          * It is possible for a power_up request to happen concurrently
  80          * with a power_down request for the same CPU. In this case the
  81          * power_down method might not be able to actually enter a
  82          * powered down state with the WFI instruction if the power_up
  83          * method has removed the required reset condition.  The
  84          * power_down method is then allowed to return. We must perform
  85          * a re-entry in the kernel as if the power_up method just had
  86          * deasserted reset on the CPU.
  87          *
  88          * To simplify race issues, the platform specific implementation
  89          * must accommodate for the possibility of unordered calls to
  90          * power_down and power_up with a usage count. Therefore, if a
  91          * call to power_up is issued for a CPU that is not down, then
  92          * the next call to power_down must not attempt a full shutdown
  93          * but only do the minimum (normally disabling L1 cache and CPU
  94          * coherency) and return just as if a concurrent power_up request
  95          * had happened as described above.
  96          */
  97
  98         phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset);
  99         phys_reset(virt_to_phys(mcpm_entry_point));
 100
 101         /* should never get here */
 102         BUG();
 103 }
 104
 105 int mcpm_cpu_power_down_finish(unsigned int cpu, unsigned int cluster)
 106 {
 107         int ret;
 108
 109         if (WARN_ON_ONCE(!platform_ops || !platform_ops->power_down_finish))
 110                 return -EUNATCH;
 111
 112         ret = platform_ops->power_down_finish(cpu, cluster);
 113         if (ret)
 114                 pr_warn("%s: cpu %u, cluster %u failed to power down (%d)\n",
 115                         __func__, cpu, cluster, ret);
 116
 117         return ret;
 118 }
 119
 120 void mcpm_cpu_suspend(u64 expected_residency)
 121 {
 122         phys_reset_t phys_reset;
 123
 124         if (WARN_ON_ONCE(!platform_ops || !platform_ops->suspend))
 125                 return;
 126         BUG_ON(!irqs_disabled());
 127
 128         /* Very similar to mcpm_cpu_power_down() */
 129         setup_mm_for_reboot();
 130         platform_ops->suspend(expected_residency);
 131         phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset);
 132         phys_reset(virt_to_phys(mcpm_entry_point));
 133         BUG();
 134 }
 135
 136 int mcpm_cpu_powered_up(void)
 137 {
 138         if (!platform_ops)
 139                 return -EUNATCH;
 140         if (platform_ops->powered_up)
 141                 platform_ops->powered_up();
 142         return 0;
 143 }
 144
 145 struct sync_struct mcpm_sync;
 146
 147 /*
 148  * __mcpm_cpu_going_down: Indicates that the cpu is being torn down.
 149  *    This must be called at the point of committing to teardown of a CPU.
 150  *    The CPU cache (SCTRL.C bit) is expected to still be active.
 151  */
 152 void __mcpm_cpu_going_down(unsigned int cpu, unsigned int cluster)
 153 {
 154         mcpm_sync.clusters[cluster].cpus[cpu].cpu = CPU_GOING_DOWN;
 155         sync_cache_w(&mcpm_sync.clusters[cluster].cpus[cpu].cpu);
 156 }
 157
 158 /*
 159  * __mcpm_cpu_down: Indicates that cpu teardown is complete and that the
 160  *    cluster can be torn down without disrupting this CPU.
 161  *    To avoid deadlocks, this must be called before a CPU is powered down.
 162  *    The CPU cache (SCTRL.C bit) is expected to be off.
 163  *    However L2 cache might or might not be active.
 164  */
 165 void __mcpm_cpu_down(unsigned int cpu, unsigned int cluster)
 166 {
 167         dmb();
 168         mcpm_sync.clusters[cluster].cpus[cpu].cpu = CPU_DOWN;
 169         sync_cache_w(&mcpm_sync.clusters[cluster].cpus[cpu].cpu);
 170         dsb_sev();
 171 }
 172
 173 /*
 174  * __mcpm_outbound_leave_critical: Leave the cluster teardown critical section.
 175  * @state: the final state of the cluster:
 176  *     CLUSTER_UP: no destructive teardown was done and the cluster has been
 177  *         restored to the previous state (CPU cache still active); or
 178  *     CLUSTER_DOWN: the cluster has been torn-down, ready for power-off
 179  *         (CPU cache disabled, L2 cache either enabled or disabled).
 180  */
 181 void __mcpm_outbound_leave_critical(unsigned int cluster, int state)
 182 {
 183         dmb();
 184         mcpm_sync.clusters[cluster].cluster = state;
 185         sync_cache_w(&mcpm_sync.clusters[cluster].cluster);
 186         dsb_sev();
 187 }
 188
 189 /*
 190  * __mcpm_outbound_enter_critical: Enter the cluster teardown critical section.
 191  * This function should be called by the last man, after local CPU teardown
 192  * is complete.  CPU cache expected to be active.
 193  *
 194  * Returns:
 195  *     false: the critical section was not entered because an inbound CPU was
 196  *         observed, or the cluster is already being set up;
 197  *     true: the critical section was entered: it is now safe to tear down the
 198  *         cluster.
 199  */
 200 bool __mcpm_outbound_enter_critical(unsigned int cpu, unsigned int cluster)
 201 {
 202         unsigned int i;
 203         struct mcpm_sync_struct *c = &mcpm_sync.clusters[cluster];
 204
 205         /* Warn inbound CPUs that the cluster is being torn down: */
 206         c->cluster = CLUSTER_GOING_DOWN;
 207         sync_cache_w(&c->cluster);
 208
 209         /* Back out if the inbound cluster is already in the critical region: */
 210         sync_cache_r(&c->inbound);
 211         if (c->inbound == INBOUND_COMING_UP)
 212                 goto abort;
 213
 214         /*
 215          * Wait for all CPUs to get out of the GOING_DOWN state, so that local
 216          * teardown is complete on each CPU before tearing down the cluster.
 217          *
 218          * If any CPU has been woken up again from the DOWN state, then we
 219          * shouldn't be taking the cluster down at all: abort in that case.
 220          */
 221         sync_cache_r(&c->cpus);
 222         for (i = 0; i < MAX_CPUS_PER_CLUSTER; i++) {
 223                 int cpustate;
 224
 225                 if (i == cpu)
 226                         continue;
 227
 228                 while (1) {
 229                         cpustate = c->cpus[i].cpu;
 230                         if (cpustate != CPU_GOING_DOWN)
 231                                 break;
 232
 233                         wfe();
 234                         sync_cache_r(&c->cpus[i].cpu);
 235                 }
 236
 237                 switch (cpustate) {
 238                 case CPU_DOWN:
 239                         continue;
 240
 241                 default:
 242                         goto abort;
 243                 }
 244         }
 245
 246         return true;
 247
 248 abort:
 249         __mcpm_outbound_leave_critical(cluster, CLUSTER_UP);
 250         return false;
 251 }
 252
 253 int __mcpm_cluster_state(unsigned int cluster)
 254 {
 255         sync_cache_r(&mcpm_sync.clusters[cluster].cluster);
 256         return mcpm_sync.clusters[cluster].cluster;
 257 }
 258
 259 extern unsigned long mcpm_power_up_setup_phys;
 260
 261 int __init mcpm_sync_init(
 262         void (*power_up_setup)(unsigned int affinity_level))
 263 {
 264         unsigned int i, j, mpidr, this_cluster;
 265
 266         BUILD_BUG_ON(MCPM_SYNC_CLUSTER_SIZE * MAX_NR_CLUSTERS != sizeof mcpm_sync);
 267         BUG_ON((unsigned long)&mcpm_sync & (__CACHE_WRITEBACK_GRANULE - 1));
 268
 269         /*
 270          * Set initial CPU and cluster states.
 271          * Only one cluster is assumed to be active at this point.
 272          */
 273         for (i = 0; i < MAX_NR_CLUSTERS; i++) {
 274                 mcpm_sync.clusters[i].cluster = CLUSTER_DOWN;
 275                 mcpm_sync.clusters[i].inbound = INBOUND_NOT_COMING_UP;
 276                 for (j = 0; j < MAX_CPUS_PER_CLUSTER; j++)
 277                         mcpm_sync.clusters[i].cpus[j].cpu = CPU_DOWN;
 278         }
 279         mpidr = read_cpuid_mpidr();
 280         this_cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
 281         for_each_online_cpu(i)
 282                 mcpm_sync.clusters[this_cluster].cpus[i].cpu = CPU_UP;
 283         mcpm_sync.clusters[this_cluster].cluster = CLUSTER_UP;
 284         sync_cache_w(&mcpm_sync);
 285
 286         if (power_up_setup) {
 287                 mcpm_power_up_setup_phys = virt_to_phys(power_up_setup);
 288                 sync_cache_w(&mcpm_power_up_setup_phys);
 289         }
 290
 291         return 0;
 292 }