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