1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * ARM/ARM64 generic CPU idle driver.
4 *
5 * Copyright (C) 2014 ARM Ltd.
6 * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
7 */
8
9 #define pr_fmt(fmt) "CPUidle arm: " fmt
10
11 #include <linux/cpuidle.h>
12 #include <linux/cpumask.h>
13 #include <linux/cpu_pm.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/of.h>
17 #include <linux/slab.h>
18
19 #include <asm/cpuidle.h>
20
21 #include "dt_idle_states.h"
22
23 /*
24 * arm_enter_idle_state - Programs CPU to enter the specified state
25 *
26 * dev: cpuidle device
27 * drv: cpuidle driver
28 * idx: state index
29 *
30 * Called from the CPUidle framework to program the device to the
31 * specified target state selected by the governor.
32 */
33 static int arm_enter_idle_state(struct cpuidle_device *dev,
34 struct cpuidle_driver *drv, int idx)
35 {
36 /*
37 * Pass idle state index to arm_cpuidle_suspend which in turn
38 * will call the CPU ops suspend protocol with idle index as a
39 * parameter.
40 */
41 return CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, idx);
42 }
43
44 static struct cpuidle_driver arm_idle_driver __initdata = {
45 .name = "arm_idle",
46 .owner = THIS_MODULE,
47 /*
48 * State at index 0 is standby wfi and considered standard
49 * on all ARM platforms. If in some platforms simple wfi
50 * can't be used as "state 0", DT bindings must be implemented
51 * to work around this issue and allow installing a special
52 * handler for idle state index 0.
53 */
54 .states[0] = {
55 .enter = arm_enter_idle_state,
56 .exit_latency = 1,
57 .target_residency = 1,
58 .power_usage = UINT_MAX,
59 .name = "WFI",
60 .desc = "ARM WFI",
61 }
62 };
63
64 static const struct of_device_id arm_idle_state_match[] __initconst = {
65 { .compatible = "arm,idle-state",
66 .data = arm_enter_idle_state },
67 { },
68 };
69
70 /*
71 * arm_idle_init_cpu
72 *
73 * Registers the arm specific cpuidle driver with the cpuidle
74 * framework. It relies on core code to parse the idle states
75 * and initialize them using driver data structures accordingly.
76 */
77 static int __init arm_idle_init_cpu(int cpu)
78 {
79 int ret;
80 struct cpuidle_driver *drv;
81
82 drv = kmemdup(&arm_idle_driver, sizeof(*drv), GFP_KERNEL);
83 if (!drv)
84 return -ENOMEM;
85
86 drv->cpumask = (struct cpumask *)cpumask_of(cpu);
87
88 /*
89 * Initialize idle states data, starting at index 1. This
90 * driver is DT only, if no DT idle states are detected (ret
91 * == 0) let the driver initialization fail accordingly since
92 * there is no reason to initialize the idle driver if only
93 * wfi is supported.
94 */
95 ret = dt_init_idle_driver(drv, arm_idle_state_match, 1);
96 if (ret <= 0) {
97 ret = ret ? : -ENODEV;
98 goto out_kfree_drv;
99 }
100
101 /*
102 * Call arch CPU operations in order to initialize
103 * idle states suspend back-end specific data
104 */
105 ret = arm_cpuidle_init(cpu);
106
107 /*
108 * Allow the initialization to continue for other CPUs, if the
109 * reported failure is a HW misconfiguration/breakage (-ENXIO).
110 *
111 * Some platforms do not support idle operations
112 * (arm_cpuidle_init() returning -EOPNOTSUPP), we should
113 * not flag this case as an error, it is a valid
114 * configuration.
115 */
116 if (ret) {
117 if (ret != -EOPNOTSUPP)
118 pr_err("CPU %d failed to init idle CPU ops\n", cpu);
119 ret = ret == -ENXIO ? 0 : ret;
120 goto out_kfree_drv;
121 }
122
123 ret = cpuidle_register(drv, NULL);
124 if (ret)
125 goto out_kfree_drv;
126
127 return 0;
128
129 out_kfree_drv:
130 kfree(drv);
131 return ret;
132 }
133
134 /*
135 * arm_idle_init - Initializes arm cpuidle driver
136 *
137 * Initializes arm cpuidle driver for all CPUs, if any CPU fails
138 * to register cpuidle driver then rollback to cancel all CPUs
139 * registeration.
140 */
141 static int __init arm_idle_init(void)
142 {
143 int cpu, ret;
144 struct cpuidle_driver *drv;
145 struct cpuidle_device *dev;
146
147 for_each_possible_cpu(cpu) {
148 ret = arm_idle_init_cpu(cpu);
149 if (ret)
150 goto out_fail;
151 }
152
153 return 0;
154
155 out_fail:
156 while (--cpu >= 0) {
157 dev = per_cpu(cpuidle_devices, cpu);
158 drv = cpuidle_get_cpu_driver(dev);
159 cpuidle_unregister(drv);
160 kfree(drv);
161 }
162
163 return ret;
164 }
165 device_initcall(arm_idle_init);