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 */
arm_enter_idle_state(struct cpuidle_device * dev,struct cpuidle_driver * drv,int idx)37 static 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
48 static 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
68 static 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 */
arm_idle_init_cpu(int cpu)81 static int __init arm_idle_init_cpu(int cpu)
82 {
83 int ret;
84 struct cpuidle_driver *drv;
85 struct cpuidle_device *dev;
86
87 drv = kmemdup(&arm_idle_driver, sizeof(*drv), GFP_KERNEL);
88 if (!drv)
89 return -ENOMEM;
90
91 drv->cpumask = (struct cpumask *)cpumask_of(cpu);
92
93 /*
94 * Initialize idle states data, starting at index 1. This
95 * driver is DT only, if no DT idle states are detected (ret
96 * == 0) let the driver initialization fail accordingly since
97 * there is no reason to initialize the idle driver if only
98 * wfi is supported.
99 */
100 ret = dt_init_idle_driver(drv, arm_idle_state_match, 1);
101 if (ret <= 0) {
102 ret = ret ? : -ENODEV;
103 goto out_kfree_drv;
104 }
105
106 /*
107 * Call arch CPU operations in order to initialize
108 * idle states suspend back-end specific data
109 */
110 ret = arm_cpuidle_init(cpu);
111
112 /*
113 * Allow the initialization to continue for other CPUs, if the reported
114 * failure is a HW misconfiguration/breakage (-ENXIO).
115 */
116 if (ret) {
117 pr_err("CPU %d failed to init idle CPU ops\n", cpu);
118 ret = ret == -ENXIO ? 0 : ret;
119 goto out_kfree_drv;
120 }
121
122 ret = cpuidle_register_driver(drv);
123 if (ret) {
124 if (ret != -EBUSY)
125 pr_err("Failed to register cpuidle driver\n");
126 goto out_kfree_drv;
127 }
128
129 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
130 if (!dev) {
131 ret = -ENOMEM;
132 goto out_unregister_drv;
133 }
134 dev->cpu = cpu;
135
136 ret = cpuidle_register_device(dev);
137 if (ret) {
138 pr_err("Failed to register cpuidle device for CPU %d\n",
139 cpu);
140 goto out_kfree_dev;
141 }
142
143 return 0;
144
145 out_kfree_dev:
146 kfree(dev);
147 out_unregister_drv:
148 cpuidle_unregister_driver(drv);
149 out_kfree_drv:
150 kfree(drv);
151 return ret;
152 }
153
154 /*
155 * arm_idle_init - Initializes arm cpuidle driver
156 *
157 * Initializes arm cpuidle driver for all CPUs, if any CPU fails
158 * to register cpuidle driver then rollback to cancel all CPUs
159 * registeration.
160 */
arm_idle_init(void)161 static int __init arm_idle_init(void)
162 {
163 int cpu, ret;
164 struct cpuidle_driver *drv;
165 struct cpuidle_device *dev;
166
167 for_each_possible_cpu(cpu) {
168 ret = arm_idle_init_cpu(cpu);
169 if (ret)
170 goto out_fail;
171 }
172
173 return 0;
174
175 out_fail:
176 while (--cpu >= 0) {
177 dev = per_cpu(cpuidle_devices, cpu);
178 drv = cpuidle_get_cpu_driver(dev);
179 cpuidle_unregister_device(dev);
180 cpuidle_unregister_driver(drv);
181 kfree(dev);
182 kfree(drv);
183 }
184
185 return ret;
186 }
187 device_initcall(arm_idle_init);
188