1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (c) 2012 Linaro : Daniel Lezcano <daniel.lezcano@linaro.org> (IBM)
4  *
5  * Based on the work of Rickard Andersson <rickard.andersson@stericsson.com>
6  * and Jonas Aaberg <jonas.aberg@stericsson.com>.
7  */
8 
9 #include <linux/init.h>
10 #include <linux/cpuidle.h>
11 #include <linux/spinlock.h>
12 #include <linux/atomic.h>
13 #include <linux/smp.h>
14 #include <linux/mfd/dbx500-prcmu.h>
15 #include <linux/platform_data/arm-ux500-pm.h>
16 #include <linux/platform_device.h>
17 
18 #include <asm/cpuidle.h>
19 
20 static atomic_t master = ATOMIC_INIT(0);
21 static DEFINE_SPINLOCK(master_lock);
22 
ux500_enter_idle(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)23 static inline int ux500_enter_idle(struct cpuidle_device *dev,
24 				   struct cpuidle_driver *drv, int index)
25 {
26 	int this_cpu = smp_processor_id();
27 	bool recouple = false;
28 
29 	if (atomic_inc_return(&master) == num_online_cpus()) {
30 
31 		/* With this lock, we prevent the other cpu to exit and enter
32 		 * this function again and become the master */
33 		if (!spin_trylock(&master_lock))
34 			goto wfi;
35 
36 		/* decouple the gic from the A9 cores */
37 		if (prcmu_gic_decouple()) {
38 			spin_unlock(&master_lock);
39 			goto out;
40 		}
41 
42 		/* If an error occur, we will have to recouple the gic
43 		 * manually */
44 		recouple = true;
45 
46 		/* At this state, as the gic is decoupled, if the other
47 		 * cpu is in WFI, we have the guarantee it won't be wake
48 		 * up, so we can safely go to retention */
49 		if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
50 			goto out;
51 
52 		/* The prcmu will be in charge of watching the interrupts
53 		 * and wake up the cpus */
54 		if (prcmu_copy_gic_settings())
55 			goto out;
56 
57 		/* Check in the meantime an interrupt did
58 		 * not occur on the gic ... */
59 		if (prcmu_gic_pending_irq())
60 			goto out;
61 
62 		/* ... and the prcmu */
63 		if (prcmu_pending_irq())
64 			goto out;
65 
66 		/* Go to the retention state, the prcmu will wait for the
67 		 * cpu to go WFI and this is what happens after exiting this
68 		 * 'master' critical section */
69 		if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
70 			goto out;
71 
72 		/* When we switch to retention, the prcmu is in charge
73 		 * of recoupling the gic automatically */
74 		recouple = false;
75 
76 		spin_unlock(&master_lock);
77 	}
78 wfi:
79 	cpu_do_idle();
80 out:
81 	atomic_dec(&master);
82 
83 	if (recouple) {
84 		prcmu_gic_recouple();
85 		spin_unlock(&master_lock);
86 	}
87 
88 	return index;
89 }
90 
91 static struct cpuidle_driver ux500_idle_driver = {
92 	.name = "ux500_idle",
93 	.owner = THIS_MODULE,
94 	.states = {
95 		ARM_CPUIDLE_WFI_STATE,
96 		{
97 			.enter		  = ux500_enter_idle,
98 			.exit_latency	  = 70,
99 			.target_residency = 260,
100 			.flags		  = CPUIDLE_FLAG_TIMER_STOP,
101 			.name		  = "ApIdle",
102 			.desc		  = "ARM Retention",
103 		},
104 	},
105 	.safe_state_index = 0,
106 	.state_count = 2,
107 };
108 
dbx500_cpuidle_probe(struct platform_device * pdev)109 static int dbx500_cpuidle_probe(struct platform_device *pdev)
110 {
111 	/* Configure wake up reasons */
112 	prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
113 			     PRCMU_WAKEUP(ABB));
114 
115 	return cpuidle_register(&ux500_idle_driver, NULL);
116 }
117 
118 static struct platform_driver dbx500_cpuidle_plat_driver = {
119 	.driver = {
120 		.name = "db8500-cpuidle",
121 	},
122 	.probe = dbx500_cpuidle_probe,
123 };
124 builtin_platform_driver(dbx500_cpuidle_plat_driver);
125