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3299b63d LP |
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 | */ | |
36 | static 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 | ||
61 | static 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, | |
3299b63d LP |
76 | .name = "WFI", |
77 | .desc = "ARM64 WFI", | |
78 | } | |
79 | }; | |
80 | ||
81 | static 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 | */ | |
94 | static 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; |
3299b63d LP |
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); |
3299b63d LP |
122 | } |
123 | device_initcall(arm64_idle_init); |