arch/arm/mach-vexpress/tc2_pm.c

   1 /*
   2  * arch/arm/mach-vexpress/tc2_pm.c - TC2 power management support
   3  *
   4  * Created by:  Nicolas Pitre, October 2012
   5  * Copyright:   (C) 2012-2013  Linaro Limited
   6  *
   7  * Some portions of this file were originally written by Achin Gupta
   8  * Copyright:   (C) 2012  ARM Limited
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  */
  14
  15 #include <linux/delay.h>
  16 #include <linux/init.h>
  17 #include <linux/io.h>
  18 #include <linux/kernel.h>
  19 #include <linux/of_address.h>
  20 #include <linux/of_irq.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/errno.h>
  23 #include <linux/irqchip/arm-gic.h>
  24
  25 #include <asm/mcpm.h>
  26 #include <asm/proc-fns.h>
  27 #include <asm/cacheflush.h>
  28 #include <asm/cputype.h>
  29 #include <asm/cp15.h>
  30
  31 #include <linux/arm-cci.h>
  32
  33 #include "spc.h"
  34
  35 /* SCC conf registers */
  36 #define RESET_CTRL              0x018
  37 #define RESET_A15_NCORERESET(cpu)       (1 << (2 + (cpu)))
  38 #define RESET_A7_NCORERESET(cpu)        (1 << (16 + (cpu)))
  39
  40 #define A15_CONF                0x400
  41 #define A7_CONF                 0x500
  42 #define SYS_INFO                0x700
  43 #define SPC_BASE                0xb00
  44
  45 static void __iomem *scc;
  46
  47 /*
  48  * We can't use regular spinlocks. In the switcher case, it is possible
  49  * for an outbound CPU to call power_down() after its inbound counterpart
  50  * is already live using the same logical CPU number which trips lockdep
  51  * debugging.
  52  */
  53 static arch_spinlock_t tc2_pm_lock = __ARCH_SPIN_LOCK_UNLOCKED;
  54
  55 #define TC2_CLUSTERS                    2
  56 #define TC2_MAX_CPUS_PER_CLUSTER        3
  57
  58 static unsigned int tc2_nr_cpus[TC2_CLUSTERS];
  59
  60 /* Keep per-cpu usage count to cope with unordered up/down requests */
  61 static int tc2_pm_use_count[TC2_MAX_CPUS_PER_CLUSTER][TC2_CLUSTERS];
  62
  63 #define tc2_cluster_unused(cluster) \
  64         (!tc2_pm_use_count[0][cluster] && \
  65          !tc2_pm_use_count[1][cluster] && \
  66          !tc2_pm_use_count[2][cluster])
  67
  68 static int tc2_pm_power_up(unsigned int cpu, unsigned int cluster)
  69 {
  70         pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
  71         if (cluster >= TC2_CLUSTERS || cpu >= tc2_nr_cpus[cluster])
  72                 return -EINVAL;
  73
  74         /*
  75          * Since this is called with IRQs enabled, and no arch_spin_lock_irq
  76          * variant exists, we need to disable IRQs manually here.
  77          */
  78         local_irq_disable();
  79         arch_spin_lock(&tc2_pm_lock);
  80
  81         if (tc2_cluster_unused(cluster))
  82                 ve_spc_powerdown(cluster, false);
  83
  84         tc2_pm_use_count[cpu][cluster]++;
  85         if (tc2_pm_use_count[cpu][cluster] == 1) {
  86                 ve_spc_set_resume_addr(cluster, cpu,
  87                                        virt_to_phys(mcpm_entry_point));
  88                 ve_spc_cpu_wakeup_irq(cluster, cpu, true);
  89         } else if (tc2_pm_use_count[cpu][cluster] != 2) {
  90                 /*
  91                  * The only possible values are:
  92                  * 0 = CPU down
  93                  * 1 = CPU (still) up
  94                  * 2 = CPU requested to be up before it had a chance
  95                  *     to actually make itself down.
  96                  * Any other value is a bug.
  97                  */
  98                 BUG();
  99         }
 100
 101         arch_spin_unlock(&tc2_pm_lock);
 102         local_irq_enable();
 103
 104         return 0;
 105 }
 106
 107 static void tc2_pm_down(u64 residency)
 108 {
 109         unsigned int mpidr, cpu, cluster;
 110         bool last_man = false, skip_wfi = false;
 111
 112         mpidr = read_cpuid_mpidr();
 113         cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
 114         cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
 115
 116         pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
 117         BUG_ON(cluster >= TC2_CLUSTERS || cpu >= TC2_MAX_CPUS_PER_CLUSTER);
 118
 119         __mcpm_cpu_going_down(cpu, cluster);
 120
 121         arch_spin_lock(&tc2_pm_lock);
 122         BUG_ON(__mcpm_cluster_state(cluster) != CLUSTER_UP);
 123         tc2_pm_use_count[cpu][cluster]--;
 124         if (tc2_pm_use_count[cpu][cluster] == 0) {
 125                 ve_spc_cpu_wakeup_irq(cluster, cpu, true);
 126                 if (tc2_cluster_unused(cluster)) {
 127                         ve_spc_powerdown(cluster, true);
 128                         ve_spc_global_wakeup_irq(true);
 129                         last_man = true;
 130                 }
 131         } else if (tc2_pm_use_count[cpu][cluster] == 1) {
 132                 /*
 133                  * A power_up request went ahead of us.
 134                  * Even if we do not want to shut this CPU down,
 135                  * the caller expects a certain state as if the WFI
 136                  * was aborted.  So let's continue with cache cleaning.
 137                  */
 138                 skip_wfi = true;
 139         } else
 140                 BUG();
 141
 142         /*
 143          * If the CPU is committed to power down, make sure
 144          * the power controller will be in charge of waking it
 145          * up upon IRQ, ie IRQ lines are cut from GIC CPU IF
 146          * to the CPU by disabling the GIC CPU IF to prevent wfi
 147          * from completing execution behind power controller back
 148          */
 149         if (!skip_wfi)
 150                 gic_cpu_if_down();
 151
 152         if (last_man && __mcpm_outbound_enter_critical(cpu, cluster)) {
 153                 arch_spin_unlock(&tc2_pm_lock);
 154
 155                 if (read_cpuid_part_number() == ARM_CPU_PART_CORTEX_A15) {
 156                         /*
 157                          * On the Cortex-A15 we need to disable
 158                          * L2 prefetching before flushing the cache.
 159                          */
 160                         asm volatile(
 161                         "mcr    p15, 1, %0, c15, c0, 3 \n\t"
 162                         "isb    \n\t"
 163                         "dsb    "
 164                         : : "r" (0x400) );
 165                 }
 166
 167                 v7_exit_coherency_flush(all);
 168
 169                 cci_disable_port_by_cpu(mpidr);
 170
 171                 __mcpm_outbound_leave_critical(cluster, CLUSTER_DOWN);
 172         } else {
 173                 /*
 174                  * If last man then undo any setup done previously.
 175                  */
 176                 if (last_man) {
 177                         ve_spc_powerdown(cluster, false);
 178                         ve_spc_global_wakeup_irq(false);
 179                 }
 180
 181                 arch_spin_unlock(&tc2_pm_lock);
 182
 183                 v7_exit_coherency_flush(louis);
 184         }
 185
 186         __mcpm_cpu_down(cpu, cluster);
 187
 188         /* Now we are prepared for power-down, do it: */
 189         if (!skip_wfi)
 190                 wfi();
 191
 192         /* Not dead at this point?  Let our caller cope. */
 193 }
 194
 195 static void tc2_pm_power_down(void)
 196 {
 197         tc2_pm_down(0);
 198 }
 199
 200 static int tc2_core_in_reset(unsigned int cpu, unsigned int cluster)
 201 {
 202         u32 mask = cluster ?
 203                   RESET_A7_NCORERESET(cpu)
 204                 : RESET_A15_NCORERESET(cpu);
 205
 206         return !(readl_relaxed(scc + RESET_CTRL) & mask);
 207 }
 208
 209 #define POLL_MSEC 10
 210 #define TIMEOUT_MSEC 1000
 211
 212 static int tc2_pm_wait_for_powerdown(unsigned int cpu, unsigned int cluster)
 213 {
 214         unsigned tries;
 215
 216         pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
 217         BUG_ON(cluster >= TC2_CLUSTERS || cpu >= TC2_MAX_CPUS_PER_CLUSTER);
 218
 219         for (tries = 0; tries < TIMEOUT_MSEC / POLL_MSEC; ++tries) {
 220                 /*
 221                  * Only examine the hardware state if the target CPU has
 222                  * caught up at least as far as tc2_pm_down():
 223                  */
 224                 if (ACCESS_ONCE(tc2_pm_use_count[cpu][cluster]) == 0) {
 225                         pr_debug("%s(cpu=%u, cluster=%u): RESET_CTRL = 0x%08X\n",
 226                                  __func__, cpu, cluster,
 227                                  readl_relaxed(scc + RESET_CTRL));
 228
 229                         /*
 230                          * We need the CPU to reach WFI, but the power
 231                          * controller may put the cluster in reset and
 232                          * power it off as soon as that happens, before
 233                          * we have a chance to see STANDBYWFI.
 234                          *
 235                          * So we need to check for both conditions:
 236                          */
 237                         if (tc2_core_in_reset(cpu, cluster) ||
 238                             ve_spc_cpu_in_wfi(cpu, cluster))
 239                                 return 0; /* success: the CPU is halted */
 240                 }
 241
 242                 /* Otherwise, wait and retry: */
 243                 msleep(POLL_MSEC);
 244         }
 245
 246         return -ETIMEDOUT; /* timeout */
 247 }
 248
 249 static void tc2_pm_suspend(u64 residency)
 250 {
 251         unsigned int mpidr, cpu, cluster;
 252
 253         mpidr = read_cpuid_mpidr();
 254         cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
 255         cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
 256         ve_spc_set_resume_addr(cluster, cpu, virt_to_phys(mcpm_entry_point));
 257         tc2_pm_down(residency);
 258 }
 259
 260 static void tc2_pm_powered_up(void)
 261 {
 262         unsigned int mpidr, cpu, cluster;
 263         unsigned long flags;
 264
 265         mpidr = read_cpuid_mpidr();
 266         cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
 267         cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
 268
 269         pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
 270         BUG_ON(cluster >= TC2_CLUSTERS || cpu >= TC2_MAX_CPUS_PER_CLUSTER);
 271
 272         local_irq_save(flags);
 273         arch_spin_lock(&tc2_pm_lock);
 274
 275         if (tc2_cluster_unused(cluster)) {
 276                 ve_spc_powerdown(cluster, false);
 277                 ve_spc_global_wakeup_irq(false);
 278         }
 279
 280         if (!tc2_pm_use_count[cpu][cluster])
 281                 tc2_pm_use_count[cpu][cluster] = 1;
 282
 283         ve_spc_cpu_wakeup_irq(cluster, cpu, false);
 284         ve_spc_set_resume_addr(cluster, cpu, 0);
 285
 286         arch_spin_unlock(&tc2_pm_lock);
 287         local_irq_restore(flags);
 288 }
 289
 290 static const struct mcpm_platform_ops tc2_pm_power_ops = {
 291         .power_up               = tc2_pm_power_up,
 292         .power_down             = tc2_pm_power_down,
 293         .wait_for_powerdown     = tc2_pm_wait_for_powerdown,
 294         .suspend                = tc2_pm_suspend,
 295         .powered_up             = tc2_pm_powered_up,
 296 };
 297
 298 static bool __init tc2_pm_usage_count_init(void)
 299 {
 300         unsigned int mpidr, cpu, cluster;
 301
 302         mpidr = read_cpuid_mpidr();
 303         cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
 304         cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
 305
 306         pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
 307         if (cluster >= TC2_CLUSTERS || cpu >= tc2_nr_cpus[cluster]) {
 308                 pr_err("%s: boot CPU is out of bound!\n", __func__);
 309                 return false;
 310         }
 311         tc2_pm_use_count[cpu][cluster] = 1;
 312         return true;
 313 }
 314
 315 /*
 316  * Enable cluster-level coherency, in preparation for turning on the MMU.
 317  */
 318 static void __naked tc2_pm_power_up_setup(unsigned int affinity_level)
 319 {
 320         asm volatile (" \n"
 321 "       cmp     r0, #1 \n"
 322 "       bxne    lr \n"
 323 "       b       cci_enable_port_for_self ");
 324 }
 325
 326 static int __init tc2_pm_init(void)
 327 {
 328         int ret, irq;
 329         u32 a15_cluster_id, a7_cluster_id, sys_info;
 330         struct device_node *np;
 331
 332         /*
 333          * The power management-related features are hidden behind
 334          * SCC registers. We need to extract runtime information like
 335          * cluster ids and number of CPUs really available in clusters.
 336          */
 337         np = of_find_compatible_node(NULL, NULL,
 338                         "arm,vexpress-scc,v2p-ca15_a7");
 339         scc = of_iomap(np, 0);
 340         if (!scc)
 341                 return -ENODEV;
 342
 343         a15_cluster_id = readl_relaxed(scc + A15_CONF) & 0xf;
 344         a7_cluster_id = readl_relaxed(scc + A7_CONF) & 0xf;
 345         if (a15_cluster_id >= TC2_CLUSTERS || a7_cluster_id >= TC2_CLUSTERS)
 346                 return -EINVAL;
 347
 348         sys_info = readl_relaxed(scc + SYS_INFO);
 349         tc2_nr_cpus[a15_cluster_id] = (sys_info >> 16) & 0xf;
 350         tc2_nr_cpus[a7_cluster_id] = (sys_info >> 20) & 0xf;
 351
 352         irq = irq_of_parse_and_map(np, 0);
 353
 354         /*
 355          * A subset of the SCC registers is also used to communicate
 356          * with the SPC (power controller). We need to be able to
 357          * drive it very early in the boot process to power up
 358          * processors, so we initialize the SPC driver here.
 359          */
 360         ret = ve_spc_init(scc + SPC_BASE, a15_cluster_id, irq);
 361         if (ret)
 362                 return ret;
 363
 364         if (!cci_probed())
 365                 return -ENODEV;
 366
 367         if (!tc2_pm_usage_count_init())
 368                 return -EINVAL;
 369
 370         ret = mcpm_platform_register(&tc2_pm_power_ops);
 371         if (!ret) {
 372                 mcpm_sync_init(tc2_pm_power_up_setup);
 373                 pr_info("TC2 power management initialized\n");
 374         }
 375         return ret;
 376 }
 377
 378 early_initcall(tc2_pm_init);