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Linux/arch/arm/mach-ux500/cpuidle.c

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  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/clockchips.h>
 15 #include <linux/spinlock.h>
 16 #include <linux/atomic.h>
 17 #include <linux/smp.h>
 18 #include <linux/mfd/dbx500-prcmu.h>
 19 
 20 #include <asm/cpuidle.h>
 21 #include <asm/proc-fns.h>
 22 
 23 static atomic_t master = ATOMIC_INIT(0);
 24 static DEFINE_SPINLOCK(master_lock);
 25 static DEFINE_PER_CPU(struct cpuidle_device, ux500_cpuidle_device);
 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         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &this_cpu);
 34 
 35         if (atomic_inc_return(&master) == num_online_cpus()) {
 36 
 37                 /* With this lock, we prevent the other cpu to exit and enter
 38                  * this function again and become the master */
 39                 if (!spin_trylock(&master_lock))
 40                         goto wfi;
 41 
 42                 /* decouple the gic from the A9 cores */
 43                 if (prcmu_gic_decouple())
 44                         goto out;
 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         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &this_cpu);
 93 
 94         return index;
 95 }
 96 
 97 static struct cpuidle_driver ux500_idle_driver = {
 98         .name = "ux500_idle",
 99         .owner = THIS_MODULE,
100         .en_core_tk_irqen = 1,
101         .states = {
102                 ARM_CPUIDLE_WFI_STATE,
103                 {
104                         .enter            = ux500_enter_idle,
105                         .exit_latency     = 70,
106                         .target_residency = 260,
107                         .flags            = CPUIDLE_FLAG_TIME_VALID,
108                         .name             = "ApIdle",
109                         .desc             = "ARM Retention",
110                 },
111         },
112         .safe_state_index = 0,
113         .state_count = 2,
114 };
115 
116 /*
117  * For each cpu, setup the broadcast timer because we will
118  * need to migrate the timers for the states >= ApIdle.
119  */
120 static void ux500_setup_broadcast_timer(void *arg)
121 {
122         int cpu = smp_processor_id();
123         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ON, &cpu);
124 }
125 
126 int __init ux500_idle_init(void)
127 {
128         int ret, cpu;
129         struct cpuidle_device *device;
130 
131         /* Configure wake up reasons */
132         prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
133                              PRCMU_WAKEUP(ABB));
134 
135         /*
136          * Configure the timer broadcast for each cpu, that must
137          * be done from the cpu context, so we use a smp cross
138          * call with 'on_each_cpu'.
139          */
140         on_each_cpu(ux500_setup_broadcast_timer, NULL, 1);
141 
142         ret = cpuidle_register_driver(&ux500_idle_driver);
143         if (ret) {
144                 printk(KERN_ERR "failed to register ux500 idle driver\n");
145                 return ret;
146         }
147 
148         for_each_online_cpu(cpu) {
149                 device = &per_cpu(ux500_cpuidle_device, cpu);
150                 device->cpu = cpu;
151                 ret = cpuidle_register_device(device);
152                 if (ret) {
153                         printk(KERN_ERR "Failed to register cpuidle "
154                                "device for cpu%d\n", cpu);
155                         goto out_unregister;
156                 }
157         }
158 out:
159         return ret;
160 
161 out_unregister:
162         for_each_online_cpu(cpu) {
163                 device = &per_cpu(ux500_cpuidle_device, cpu);
164                 cpuidle_unregister_device(device);
165         }
166 
167         cpuidle_unregister_driver(&ux500_idle_driver);
168         goto out;
169 }
170 
171 device_initcall(ux500_idle_init);
172 

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