tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * ARM/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 arm: " 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#include <linux/slab.h>
21#include <linux/topology.h>
22
23#include <asm/cpuidle.h>
24
25#include "dt_idle_states.h"
26
27/*
28 * arm_enter_idle_state - Programs CPU to enter the specified state
29 *
30 * dev: cpuidle device
31 * drv: cpuidle driver
32 * idx: state index
33 *
34 * Called from the CPUidle framework to program the device to the
35 * specified target state selected by the governor.
36 */
37static int arm_enter_idle_state(struct cpuidle_device *dev,
38 struct cpuidle_driver *drv, int idx)
39{
40 /*
41 * Pass idle state index to arm_cpuidle_suspend which in turn
42 * will call the CPU ops suspend protocol with idle index as a
43 * parameter.
44 */
45 return CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, idx);
46}
47
48static struct cpuidle_driver arm_idle_driver __initdata = {
49 .name = "arm_idle",
50 .owner = THIS_MODULE,
51 /*
52 * State at index 0 is standby wfi and considered standard
53 * on all ARM platforms. If in some platforms simple wfi
54 * can't be used as "state 0", DT bindings must be implemented
55 * to work around this issue and allow installing a special
56 * handler for idle state index 0.
57 */
58 .states[0] = {
59 .enter = arm_enter_idle_state,
60 .exit_latency = 1,
61 .target_residency = 1,
62 .power_usage = UINT_MAX,
63 .name = "WFI",
64 .desc = "ARM WFI",
65 }
66};
67
68static const struct of_device_id arm_idle_state_match[] __initconst = {
69 { .compatible = "arm,idle-state",
70 .data = arm_enter_idle_state },
71 { },
72};
73
74/*
75 * arm_idle_init_cpu
76 *
77 * Registers the arm specific cpuidle driver with the cpuidle
78 * framework. It relies on core code to parse the idle states
79 * and initialize them using driver data structures accordingly.
80 */
81static int __init arm_idle_init_cpu(int cpu)
82{
83 int ret;
84 struct cpuidle_driver *drv;
85
86 drv = kmemdup(&arm_idle_driver, sizeof(*drv), GFP_KERNEL);
87 if (!drv)
88 return -ENOMEM;
89
90 drv->cpumask = (struct cpumask *)cpumask_of(cpu);
91
92 /*
93 * Initialize idle states data, starting at index 1. This
94 * driver is DT only, if no DT idle states are detected (ret
95 * == 0) let the driver initialization fail accordingly since
96 * there is no reason to initialize the idle driver if only
97 * wfi is supported.
98 */
99 ret = dt_init_idle_driver(drv, arm_idle_state_match, 1);
100 if (ret <= 0) {
101 ret = ret ? : -ENODEV;
102 goto out_kfree_drv;
103 }
104
105 /*
106 * Call arch CPU operations in order to initialize
107 * idle states suspend back-end specific data
108 */
109 ret = arm_cpuidle_init(cpu);
110
111 /*
112 * Allow the initialization to continue for other CPUs, if the reported
113 * failure is a HW misconfiguration/breakage (-ENXIO).
114 */
115 if (ret) {
116 pr_err("CPU %d failed to init idle CPU ops\n", cpu);
117 ret = ret == -ENXIO ? 0 : ret;
118 goto out_kfree_drv;
119 }
120
121 ret = cpuidle_register(drv, NULL);
122 if (ret)
123 goto out_kfree_drv;
124
125 return 0;
126
127out_kfree_drv:
128 kfree(drv);
129 return ret;
130}
131
132/*
133 * arm_idle_init - Initializes arm cpuidle driver
134 *
135 * Initializes arm cpuidle driver for all CPUs, if any CPU fails
136 * to register cpuidle driver then rollback to cancel all CPUs
137 * registeration.
138 */
139static int __init arm_idle_init(void)
140{
141 int cpu, ret;
142 struct cpuidle_driver *drv;
143 struct cpuidle_device *dev;
144
145 for_each_possible_cpu(cpu) {
146 ret = arm_idle_init_cpu(cpu);
147 if (ret)
148 goto out_fail;
149 }
150
151 return 0;
152
153out_fail:
154 while (--cpu >= 0) {
155 dev = per_cpu(cpuidle_devices, cpu);
156 drv = cpuidle_get_cpu_driver(dev);
157 cpuidle_unregister(drv);
158 kfree(drv);
159 }
160
161 return ret;
162}
163device_initcall(arm_idle_init);