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Linux/drivers/cpuidle/cpuidle-ux500.c

  1 /*
  2  * Copyright (c) 2012 Linaro : Daniel Lezcano <daniel.lezcano@linaro.org> (IBM)
  3  *
  4  * Based on the work of Rickard Andersson <rickard.andersson@stericsson.com>
  5  * and Jonas Aaberg <jonas.aberg@stericsson.com>.
  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/module.h>
 13 #include <linux/cpuidle.h>
 14 #include <linux/spinlock.h>
 15 #include <linux/atomic.h>
 16 #include <linux/smp.h>
 17 #include <linux/mfd/dbx500-prcmu.h>
 18 #include <linux/platform_data/arm-ux500-pm.h>
 19 #include <linux/platform_device.h>
 20 
 21 #include <asm/cpuidle.h>
 22 #include <asm/proc-fns.h>
 23 
 24 static atomic_t master = ATOMIC_INIT(0);
 25 static DEFINE_SPINLOCK(master_lock);
 26 
 27 static inline int ux500_enter_idle(struct cpuidle_device *dev,
 28                                    struct cpuidle_driver *drv, int index)
 29 {
 30         int this_cpu = smp_processor_id();
 31         bool recouple = false;
 32 
 33         if (atomic_inc_return(&master) == num_online_cpus()) {
 34 
 35                 /* With this lock, we prevent the other cpu to exit and enter
 36                  * this function again and become the master */
 37                 if (!spin_trylock(&master_lock))
 38                         goto wfi;
 39 
 40                 /* decouple the gic from the A9 cores */
 41                 if (prcmu_gic_decouple()) {
 42                         spin_unlock(&master_lock);
 43                         goto out;
 44                 }
 45 
 46                 /* If an error occur, we will have to recouple the gic
 47                  * manually */
 48                 recouple = true;
 49 
 50                 /* At this state, as the gic is decoupled, if the other
 51                  * cpu is in WFI, we have the guarantee it won't be wake
 52                  * up, so we can safely go to retention */
 53                 if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
 54                         goto out;
 55 
 56                 /* The prcmu will be in charge of watching the interrupts
 57                  * and wake up the cpus */
 58                 if (prcmu_copy_gic_settings())
 59                         goto out;
 60 
 61                 /* Check in the meantime an interrupt did
 62                  * not occur on the gic ... */
 63                 if (prcmu_gic_pending_irq())
 64                         goto out;
 65 
 66                 /* ... and the prcmu */
 67                 if (prcmu_pending_irq())
 68                         goto out;
 69 
 70                 /* Go to the retention state, the prcmu will wait for the
 71                  * cpu to go WFI and this is what happens after exiting this
 72                  * 'master' critical section */
 73                 if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
 74                         goto out;
 75 
 76                 /* When we switch to retention, the prcmu is in charge
 77                  * of recoupling the gic automatically */
 78                 recouple = false;
 79 
 80                 spin_unlock(&master_lock);
 81         }
 82 wfi:
 83         cpu_do_idle();
 84 out:
 85         atomic_dec(&master);
 86 
 87         if (recouple) {
 88                 prcmu_gic_recouple();
 89                 spin_unlock(&master_lock);
 90         }
 91 
 92         return index;
 93 }
 94 
 95 static struct cpuidle_driver ux500_idle_driver = {
 96         .name = "ux500_idle",
 97         .owner = THIS_MODULE,
 98         .states = {
 99                 ARM_CPUIDLE_WFI_STATE,
100                 {
101                         .enter            = ux500_enter_idle,
102                         .exit_latency     = 70,
103                         .target_residency = 260,
104                         .flags            = CPUIDLE_FLAG_TIME_VALID |
105                                             CPUIDLE_FLAG_TIMER_STOP,
106                         .name             = "ApIdle",
107                         .desc             = "ARM Retention",
108                 },
109         },
110         .safe_state_index = 0,
111         .state_count = 2,
112 };
113 
114 static int dbx500_cpuidle_probe(struct platform_device *pdev)
115 {
116         /* Configure wake up reasons */
117         prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
118                              PRCMU_WAKEUP(ABB));
119 
120         return cpuidle_register(&ux500_idle_driver, NULL);
121 }
122 
123 static struct platform_driver dbx500_cpuidle_plat_driver = {
124         .driver = {
125                 .name = "cpuidle-dbx500",
126                 .owner = THIS_MODULE,
127         },
128         .probe = dbx500_cpuidle_probe,
129 };
130 
131 module_platform_driver(dbx500_cpuidle_plat_driver);
132 

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