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
20static atomic_t master = ATOMIC_INIT(0);
21static DEFINE_SPINLOCK(master_lock);
22
23static 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	}
78wfi:
79	cpu_do_idle();
80out:
81	atomic_dec(&master);
82
83	if (recouple) {
84		prcmu_gic_recouple();
85		spin_unlock(&master_lock);
86	}
87
88	return index;
89}
90
91static 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
109static 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
118static struct platform_driver dbx500_cpuidle_plat_driver = {
119	.driver = {
120		.name = "db8500-cpuidle",
121	},
122	.probe = dbx500_cpuidle_probe,
123};
124builtin_platform_driver(dbx500_cpuidle_plat_driver);
125