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[linux/fpc-iii.git] / arch / arm / mach-ux500 / cpuidle.c
blob317a2be129fb12be9b78bcdcb2286d05496ddf6f
1 /*
2 * Copyright (c) 2012 Linaro : Daniel Lezcano <daniel.lezcano@linaro.org> (IBM)
4 * Based on the work of Rickard Andersson <rickard.andersson@stericsson.com>
5 * and Jonas Aaberg <jonas.aberg@stericsson.com>.
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.
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>
20 #include <asm/cpuidle.h>
21 #include <asm/proc-fns.h>
23 #include "db8500-regs.h"
25 static atomic_t master = ATOMIC_INIT(0);
26 static DEFINE_SPINLOCK(master_lock);
28 static inline int ux500_enter_idle(struct cpuidle_device *dev,
29 struct cpuidle_driver *drv, int index)
31 int this_cpu = smp_processor_id();
32 bool recouple = false;
34 if (atomic_inc_return(&master) == num_online_cpus()) {
36 /* With this lock, we prevent the other cpu to exit and enter
37 * this function again and become the master */
38 if (!spin_trylock(&master_lock))
39 goto wfi;
41 /* decouple the gic from the A9 cores */
42 if (prcmu_gic_decouple()) {
43 spin_unlock(&master_lock);
44 goto out;
47 /* If an error occur, we will have to recouple the gic
48 * manually */
49 recouple = true;
51 /* At this state, as the gic is decoupled, if the other
52 * cpu is in WFI, we have the guarantee it won't be wake
53 * up, so we can safely go to retention */
54 if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
55 goto out;
57 /* The prcmu will be in charge of watching the interrupts
58 * and wake up the cpus */
59 if (prcmu_copy_gic_settings())
60 goto out;
62 /* Check in the meantime an interrupt did
63 * not occur on the gic ... */
64 if (prcmu_gic_pending_irq())
65 goto out;
67 /* ... and the prcmu */
68 if (prcmu_pending_irq())
69 goto out;
71 /* Go to the retention state, the prcmu will wait for the
72 * cpu to go WFI and this is what happens after exiting this
73 * 'master' critical section */
74 if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
75 goto out;
77 /* When we switch to retention, the prcmu is in charge
78 * of recoupling the gic automatically */
79 recouple = false;
81 spin_unlock(&master_lock);
83 wfi:
84 cpu_do_idle();
85 out:
86 atomic_dec(&master);
88 if (recouple) {
89 prcmu_gic_recouple();
90 spin_unlock(&master_lock);
93 return index;
96 static struct cpuidle_driver ux500_idle_driver = {
97 .name = "ux500_idle",
98 .owner = THIS_MODULE,
99 .states = {
100 ARM_CPUIDLE_WFI_STATE,
102 .enter = ux500_enter_idle,
103 .exit_latency = 70,
104 .target_residency = 260,
105 .flags = CPUIDLE_FLAG_TIME_VALID |
106 CPUIDLE_FLAG_TIMER_STOP,
107 .name = "ApIdle",
108 .desc = "ARM Retention",
111 .safe_state_index = 0,
112 .state_count = 2,
115 int __init ux500_idle_init(void)
117 /* Configure wake up reasons */
118 prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
119 PRCMU_WAKEUP(ABB));
121 return cpuidle_register(&ux500_idle_driver, NULL);
124 device_initcall(ux500_idle_init);