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/init.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
ux500_enter_idle(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)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
dbx500_cpuidle_probe(struct platform_device * pdev)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 builtin_platform_driver(dbx500_cpuidle_plat_driver);
128