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);
129