drivers/cpuidle/cpuidle-ux500.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2012 Linaro : Daniel Lezcano <daniel.lezcano@linaro.org> (IBM)
   4  *
   5  * Based on the work of Rickard Andersson <rickard.andersson@stericsson.com>
   6  * and Jonas Aaberg <jonas.aberg@stericsson.com>.
   7  */
   8
   9 #include <linux/init.h>
  10 #include <linux/cpuidle.h>
  11 #include <linux/spinlock.h>
  12 #include <linux/atomic.h>
  13 #include <linux/smp.h>
  14 #include <linux/mfd/dbx500-prcmu.h>
  15 #include <linux/platform_data/arm-ux500-pm.h>
  16 #include <linux/platform_device.h>
  17
  18 #include <asm/cpuidle.h>
  19
  20 static atomic_t master = ATOMIC_INIT(0);
  21 static DEFINE_SPINLOCK(master_lock);
  22
  23 static inline int ux500_enter_idle(struct cpuidle_device *dev,
  24                                    struct cpuidle_driver *drv, int index)
  25 {
  26         int this_cpu = smp_processor_id();
  27         bool recouple = false;
  28
  29         if (atomic_inc_return(&master) == num_online_cpus()) {
  30
  31                 /* With this lock, we prevent the other cpu to exit and enter
  32                  * this function again and become the master */
  33                 if (!spin_trylock(&master_lock))
  34                         goto wfi;
  35
  36                 /* decouple the gic from the A9 cores */
  37                 if (prcmu_gic_decouple()) {
  38                         spin_unlock(&master_lock);
  39                         goto out;
  40                 }
  41
  42                 /* If an error occur, we will have to recouple the gic
  43                  * manually */
  44                 recouple = true;
  45
  46                 /* At this state, as the gic is decoupled, if the other
  47                  * cpu is in WFI, we have the guarantee it won't be wake
  48                  * up, so we can safely go to retention */
  49                 if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
  50                         goto out;
  51
  52                 /* The prcmu will be in charge of watching the interrupts
  53                  * and wake up the cpus */
  54                 if (prcmu_copy_gic_settings())
  55                         goto out;
  56
  57                 /* Check in the meantime an interrupt did
  58                  * not occur on the gic ... */
  59                 if (prcmu_gic_pending_irq())
  60                         goto out;
  61
  62                 /* ... and the prcmu */
  63                 if (prcmu_pending_irq())
  64                         goto out;
  65
  66                 /* Go to the retention state, the prcmu will wait for the
  67                  * cpu to go WFI and this is what happens after exiting this
  68                  * 'master' critical section */
  69                 if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
  70                         goto out;
  71
  72                 /* When we switch to retention, the prcmu is in charge
  73                  * of recoupling the gic automatically */
  74                 recouple = false;
  75
  76                 spin_unlock(&master_lock);
  77         }
  78 wfi:
  79         cpu_do_idle();
  80 out:
  81         atomic_dec(&master);
  82
  83         if (recouple) {
  84                 prcmu_gic_recouple();
  85                 spin_unlock(&master_lock);
  86         }
  87
  88         return index;
  89 }
  90
  91 static struct cpuidle_driver ux500_idle_driver = {
  92         .name = "ux500_idle",
  93         .owner = THIS_MODULE,
  94         .states = {
  95                 ARM_CPUIDLE_WFI_STATE,
  96                 {
  97                         .enter            = ux500_enter_idle,
  98                         .exit_latency     = 70,
  99                         .target_residency = 260,
 100                         .flags            = CPUIDLE_FLAG_TIMER_STOP,
 101                         .name             = "ApIdle",
 102                         .desc             = "ARM Retention",
 103                 },
 104         },
 105         .safe_state_index = 0,
 106         .state_count = 2,
 107 };
 108
 109 static int dbx500_cpuidle_probe(struct platform_device *pdev)
 110 {
 111         /* Configure wake up reasons */
 112         prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
 113                              PRCMU_WAKEUP(ABB));
 114
 115         return cpuidle_register(&ux500_idle_driver, NULL);
 116 }
 117
 118 static struct platform_driver dbx500_cpuidle_plat_driver = {
 119         .driver = {
 120                 .name = "db8500-cpuidle",
 121         },
 122         .probe = dbx500_cpuidle_probe,
 123 };
 124 builtin_platform_driver(dbx500_cpuidle_plat_driver);