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  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/init.h>
  16 #include <linux/kernel.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/errno.h>
  19 #include <linux/irqchip/arm-gic.h>
  20
  21 #include <asm/mcpm.h>
  22 #include <asm/proc-fns.h>
  23 #include <asm/cacheflush.h>
  24 #include <asm/cputype.h>
  25 #include <asm/cp15.h>
  26
  27 #include <mach/motherboard.h>
  28
  29 #include <linux/vexpress.h>
  30 #include <linux/arm-cci.h>
  31
  32 /*
  33  * We can't use regular spinlocks. In the switcher case, it is possible
  34  * for an outbound CPU to call power_down() after its inbound counterpart
  35  * is already live using the same logical CPU number which trips lockdep
  36  * debugging.
  37  */
  38 static arch_spinlock_t tc2_pm_lock = __ARCH_SPIN_LOCK_UNLOCKED;
  39
  40 static int tc2_pm_use_count[3][2];
  41
  42 static int tc2_pm_power_up(unsigned int cpu, unsigned int cluster)
  43 {
  44         pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
  45         if (cluster >= 2 || cpu >= vexpress_spc_get_nb_cpus(cluster))
  46                 return -EINVAL;
  47
  48         /*
  49          * Since this is called with IRQs enabled, and no arch_spin_lock_irq
  50          * variant exists, we need to disable IRQs manually here.
  51          */
  52         local_irq_disable();
  53         arch_spin_lock(&tc2_pm_lock);
  54
  55         if (!tc2_pm_use_count[0][cluster] &&
  56             !tc2_pm_use_count[1][cluster] &&
  57             !tc2_pm_use_count[2][cluster])
  58                 vexpress_spc_powerdown_enable(cluster, 0);
  59
  60         tc2_pm_use_count[cpu][cluster]++;
  61         if (tc2_pm_use_count[cpu][cluster] == 1) {
  62                 vexpress_spc_write_bxaddr_reg(cluster, cpu,
  63                                               virt_to_phys(mcpm_entry_point));
  64                 vexpress_spc_set_cpu_wakeup_irq(cpu, cluster, 1);
  65         } else if (tc2_pm_use_count[cpu][cluster] != 2) {
  66                 /*
  67                  * The only possible values are:
  68                  * 0 = CPU down
  69                  * 1 = CPU (still) up
  70                  * 2 = CPU requested to be up before it had a chance
  71                  *     to actually make itself down.
  72                  * Any other value is a bug.
  73                  */
  74                 BUG();
  75         }
  76
  77         arch_spin_unlock(&tc2_pm_lock);
  78         local_irq_enable();
  79
  80         return 0;
  81 }
  82
  83 static void tc2_pm_power_down(void)
  84 {
  85         unsigned int mpidr, cpu, cluster;
  86         bool last_man = false, skip_wfi = false;
  87
  88         mpidr = read_cpuid_mpidr();
  89         cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
  90         cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
  91
  92         pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
  93         BUG_ON(cluster >= 2 || cpu >= vexpress_spc_get_nb_cpus(cluster));
  94
  95         __mcpm_cpu_going_down(cpu, cluster);
  96
  97         arch_spin_lock(&tc2_pm_lock);
  98         BUG_ON(__mcpm_cluster_state(cluster) != CLUSTER_UP);
  99         tc2_pm_use_count[cpu][cluster]--;
 100         if (tc2_pm_use_count[cpu][cluster] == 0) {
 101                 vexpress_spc_set_cpu_wakeup_irq(cpu, cluster, 1);
 102                 if (!tc2_pm_use_count[0][cluster] &&
 103                     !tc2_pm_use_count[1][cluster] &&
 104                     !tc2_pm_use_count[2][cluster]) {
 105                         vexpress_spc_powerdown_enable(cluster, 1);
 106                         vexpress_spc_set_global_wakeup_intr(1);
 107                         last_man = true;
 108                 }
 109         } else if (tc2_pm_use_count[cpu][cluster] == 1) {
 110                 /*
 111                  * A power_up request went ahead of us.
 112                  * Even if we do not want to shut this CPU down,
 113                  * the caller expects a certain state as if the WFI
 114                  * was aborted.  So let's continue with cache cleaning.
 115                  */
 116                 skip_wfi = true;
 117         } else
 118                 BUG();
 119
 120         gic_cpu_if_down();
 121
 122         if (last_man && __mcpm_outbound_enter_critical(cpu, cluster)) {
 123                 arch_spin_unlock(&tc2_pm_lock);
 124
 125                 set_cr(get_cr() & ~CR_C);
 126                 flush_cache_all();
 127                 asm volatile ("clrex");
 128                 set_auxcr(get_auxcr() & ~(1 << 6));
 129
 130                 disable_cci(cluster);
 131
 132                 /*
 133                  * Ensure that both C & I bits are disabled in the SCTLR
 134                  * before disabling ACE snoops. This ensures that no
 135                  * coherency traffic will originate from this cpu after
 136                  * ACE snoops are turned off.
 137                  */
 138                 cpu_proc_fin();
 139
 140                 __mcpm_outbound_leave_critical(cluster, CLUSTER_DOWN);
 141         } else {
 142                 /*
 143                  * If last man then undo any setup done previously.
 144                  */
 145                 if (last_man) {
 146                         vexpress_spc_powerdown_enable(cluster, 0);
 147                         vexpress_spc_set_global_wakeup_intr(0);
 148                 }
 149
 150                 arch_spin_unlock(&tc2_pm_lock);
 151
 152                 set_cr(get_cr() & ~CR_C);
 153                 flush_cache_louis();
 154                 asm volatile ("clrex");
 155                 set_auxcr(get_auxcr() & ~(1 << 6));
 156         }
 157
 158         __mcpm_cpu_down(cpu, cluster);
 159
 160         /* Now we are prepared for power-down, do it: */
 161         if (!skip_wfi)
 162                 wfi();
 163
 164         /* Not dead at this point?  Let our caller cope. */
 165 }
 166
 167 static void tc2_pm_powered_up(void)
 168 {
 169         unsigned int mpidr, cpu, cluster;
 170         unsigned long flags;
 171
 172         mpidr = read_cpuid_mpidr();
 173         cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
 174         cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
 175
 176         pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
 177         BUG_ON(cluster >= 2 || cpu >= vexpress_spc_get_nb_cpus(cluster));
 178
 179         local_irq_save(flags);
 180         arch_spin_lock(&tc2_pm_lock);
 181
 182         if (!tc2_pm_use_count[0][cluster] &&
 183             !tc2_pm_use_count[1][cluster] &&
 184             !tc2_pm_use_count[2][cluster]) {
 185                 vexpress_spc_powerdown_enable(cluster, 0);
 186                 vexpress_spc_set_global_wakeup_intr(0);
 187         }
 188
 189         if (!tc2_pm_use_count[cpu][cluster])
 190                 tc2_pm_use_count[cpu][cluster] = 1;
 191
 192         vexpress_spc_set_cpu_wakeup_irq(cpu, cluster, 0);
 193         vexpress_spc_write_bxaddr_reg(cluster, cpu, 0);
 194
 195         arch_spin_unlock(&tc2_pm_lock);
 196         local_irq_restore(flags);
 197 }
 198
 199 static const struct mcpm_platform_ops tc2_pm_power_ops = {
 200         .power_up       = tc2_pm_power_up,
 201         .power_down     = tc2_pm_power_down,
 202         .powered_up     = tc2_pm_powered_up,
 203 };
 204
 205 static void __init tc2_pm_usage_count_init(void)
 206 {
 207         unsigned int mpidr, cpu, cluster;
 208
 209         mpidr = read_cpuid_mpidr();
 210         cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
 211         cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
 212
 213         pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
 214         BUG_ON(cpu >= 3 || cluster >= 2);
 215         tc2_pm_use_count[cpu][cluster] = 1;
 216 }
 217
 218 extern void tc2_pm_power_up_setup(unsigned int affinity_level);
 219
 220 static int __init tc2_pm_init(void)
 221 {
 222         int ret;
 223
 224         if (!vexpress_spc_check_loaded())
 225                 return -ENODEV;
 226
 227         tc2_pm_usage_count_init();
 228
 229         ret = mcpm_platform_register(&tc2_pm_power_ops);
 230         if (!ret)
 231                 ret = mcpm_sync_init(tc2_pm_power_up_setup);
 232         if (!ret)
 233                 pr_info("TC2 power management initialized\n");
 234         return ret;
 235 }
 236
 237 early_initcall(tc2_pm_init);