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

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