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 #include <asm/proc-fns.h>
23 
24 static atomic_t master = ATOMIC_INIT(0);
25 static DEFINE_SPINLOCK(master_lock);
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 	if (atomic_inc_return(&master) == num_online_cpus()) {
34 
35 		/* With this lock, we prevent the other cpu to exit and enter
36 		 * this function again and become the master */
37 		if (!spin_trylock(&master_lock))
38 			goto wfi;
39 
40 		/* decouple the gic from the A9 cores */
41 		if (prcmu_gic_decouple()) {
42 			spin_unlock(&master_lock);
43 			goto out;
44 		}
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 	return index;
93 }
94 
95 static struct cpuidle_driver ux500_idle_driver = {
96 	.name = "ux500_idle",
97 	.owner = THIS_MODULE,
98 	.states = {
99 		ARM_CPUIDLE_WFI_STATE,
100 		{
101 			.enter		  = ux500_enter_idle,
102 			.exit_latency	  = 70,
103 			.target_residency = 260,
104 			.flags		  = CPUIDLE_FLAG_TIME_VALID |
105 			                    CPUIDLE_FLAG_TIMER_STOP,
106 			.name		  = "ApIdle",
107 			.desc		  = "ARM Retention",
108 		},
109 	},
110 	.safe_state_index = 0,
111 	.state_count = 2,
112 };
113 
114 static int __init dbx500_cpuidle_probe(struct platform_device *pdev)
115 {
116 	/* Configure wake up reasons */
117 	prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
118 			     PRCMU_WAKEUP(ABB));
119 
120 	return cpuidle_register(&ux500_idle_driver, NULL);
121 }
122 
123 static struct platform_driver dbx500_cpuidle_plat_driver = {
124 	.driver = {
125 		.name = "cpuidle-dbx500",
126 		.owner = THIS_MODULE,
127 	},
128 	.probe = dbx500_cpuidle_probe,
129 };
130 
131 module_platform_driver(dbx500_cpuidle_plat_driver);
132