GNU Linux-libre 4.4.289-gnu1
[releases.git] / 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);