Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost
[deliverable/linux.git] / drivers / cpuidle / cpuidle-arm64.c
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1/*
2 * ARM64 generic CPU idle driver.
3 *
4 * Copyright (C) 2014 ARM Ltd.
5 * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.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#define pr_fmt(fmt) "CPUidle arm64: " fmt
13
14#include <linux/cpuidle.h>
15#include <linux/cpumask.h>
16#include <linux/cpu_pm.h>
17#include <linux/kernel.h>
18#include <linux/module.h>
19#include <linux/of.h>
20
21#include <asm/cpuidle.h>
22#include <asm/suspend.h>
23
24#include "dt_idle_states.h"
25
26/*
27 * arm64_enter_idle_state - Programs CPU to enter the specified state
28 *
29 * dev: cpuidle device
30 * drv: cpuidle driver
31 * idx: state index
32 *
33 * Called from the CPUidle framework to program the device to the
34 * specified target state selected by the governor.
35 */
36static int arm64_enter_idle_state(struct cpuidle_device *dev,
37 struct cpuidle_driver *drv, int idx)
38{
39 int ret;
40
41 if (!idx) {
42 cpu_do_idle();
43 return idx;
44 }
45
46 ret = cpu_pm_enter();
47 if (!ret) {
48 /*
49 * Pass idle state index to cpu_suspend which in turn will
50 * call the CPU ops suspend protocol with idle index as a
51 * parameter.
52 */
53 ret = cpu_suspend(idx);
54
55 cpu_pm_exit();
56 }
57
58 return ret ? -1 : idx;
59}
60
61static struct cpuidle_driver arm64_idle_driver = {
62 .name = "arm64_idle",
63 .owner = THIS_MODULE,
64 /*
65 * State at index 0 is standby wfi and considered standard
66 * on all ARM platforms. If in some platforms simple wfi
67 * can't be used as "state 0", DT bindings must be implemented
68 * to work around this issue and allow installing a special
69 * handler for idle state index 0.
70 */
71 .states[0] = {
72 .enter = arm64_enter_idle_state,
73 .exit_latency = 1,
74 .target_residency = 1,
75 .power_usage = UINT_MAX,
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76 .name = "WFI",
77 .desc = "ARM64 WFI",
78 }
79};
80
81static const struct of_device_id arm64_idle_state_match[] __initconst = {
82 { .compatible = "arm,idle-state",
83 .data = arm64_enter_idle_state },
84 { },
85};
86
87/*
88 * arm64_idle_init
89 *
90 * Registers the arm64 specific cpuidle driver with the cpuidle
91 * framework. It relies on core code to parse the idle states
92 * and initialize them using driver data structures accordingly.
93 */
94static int __init arm64_idle_init(void)
95{
96 int cpu, ret;
97 struct cpuidle_driver *drv = &arm64_idle_driver;
98
99 /*
100 * Initialize idle states data, starting at index 1.
101 * This driver is DT only, if no DT idle states are detected (ret == 0)
102 * let the driver initialization fail accordingly since there is no
103 * reason to initialize the idle driver if only wfi is supported.
104 */
105 ret = dt_init_idle_driver(drv, arm64_idle_state_match, 1);
18f95a36 106 if (ret <= 0)
3299b63d 107 return ret ? : -ENODEV;
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108
109 /*
110 * Call arch CPU operations in order to initialize
111 * idle states suspend back-end specific data
112 */
113 for_each_possible_cpu(cpu) {
114 ret = cpu_init_idle(cpu);
115 if (ret) {
116 pr_err("CPU %d failed to init idle CPU ops\n", cpu);
117 return ret;
118 }
119 }
120
18f95a36 121 return cpuidle_register(drv, NULL);
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122}
123device_initcall(arm64_idle_init);
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