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/cpu_cooling.h> |
12 | #include <linux/cpuidle.h> |
13 | #include <linux/cpumask.h> |
14 | #include <linux/cpu_pm.h> |
15 | #include <linux/kernel.h> |
16 | #include <linux/module.h> |
17 | #include <linux/of.h> |
18 | #include <linux/slab.h> |
19 | |
20 | #include <asm/cpuidle.h> |
21 | |
22 | #include "dt_idle_states.h" |
23 | |
24 | /* |
25 | * arm_enter_idle_state - Programs CPU to enter the specified state |
26 | * |
27 | * dev: cpuidle device |
28 | * drv: cpuidle driver |
29 | * idx: state index |
30 | * |
31 | * Called from the CPUidle framework to program the device to the |
32 | * specified target state selected by the governor. |
33 | */ |
34 | static __cpuidle int arm_enter_idle_state(struct cpuidle_device *dev, |
35 | struct cpuidle_driver *drv, int idx) |
36 | { |
37 | /* |
38 | * Pass idle state index to arm_cpuidle_suspend which in turn |
39 | * will call the CPU ops suspend protocol with idle index as a |
40 | * parameter. |
41 | */ |
42 | return CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, idx); |
43 | } |
44 | |
45 | static struct cpuidle_driver arm_idle_driver __initdata = { |
46 | .name = "arm_idle" , |
47 | .owner = THIS_MODULE, |
48 | /* |
49 | * State at index 0 is standby wfi and considered standard |
50 | * on all ARM platforms. If in some platforms simple wfi |
51 | * can't be used as "state 0", DT bindings must be implemented |
52 | * to work around this issue and allow installing a special |
53 | * handler for idle state index 0. |
54 | */ |
55 | .states[0] = { |
56 | .enter = arm_enter_idle_state, |
57 | .exit_latency = 1, |
58 | .target_residency = 1, |
59 | .power_usage = UINT_MAX, |
60 | .name = "WFI" , |
61 | .desc = "ARM WFI" , |
62 | } |
63 | }; |
64 | |
65 | static const struct of_device_id arm_idle_state_match[] __initconst = { |
66 | { .compatible = "arm,idle-state" , |
67 | .data = arm_enter_idle_state }, |
68 | { }, |
69 | }; |
70 | |
71 | /* |
72 | * arm_idle_init_cpu |
73 | * |
74 | * Registers the arm specific cpuidle driver with the cpuidle |
75 | * framework. It relies on core code to parse the idle states |
76 | * and initialize them using driver data structures accordingly. |
77 | */ |
78 | static int __init arm_idle_init_cpu(int cpu) |
79 | { |
80 | int ret; |
81 | struct cpuidle_driver *drv; |
82 | |
83 | drv = kmemdup(p: &arm_idle_driver, size: sizeof(*drv), GFP_KERNEL); |
84 | if (!drv) |
85 | return -ENOMEM; |
86 | |
87 | drv->cpumask = (struct cpumask *)cpumask_of(cpu); |
88 | |
89 | /* |
90 | * Initialize idle states data, starting at index 1. This |
91 | * driver is DT only, if no DT idle states are detected (ret |
92 | * == 0) let the driver initialization fail accordingly since |
93 | * there is no reason to initialize the idle driver if only |
94 | * wfi is supported. |
95 | */ |
96 | ret = dt_init_idle_driver(drv, matches: arm_idle_state_match, start_idx: 1); |
97 | if (ret <= 0) { |
98 | ret = ret ? : -ENODEV; |
99 | goto out_kfree_drv; |
100 | } |
101 | |
102 | /* |
103 | * Call arch CPU operations in order to initialize |
104 | * idle states suspend back-end specific data |
105 | */ |
106 | ret = arm_cpuidle_init(cpu); |
107 | |
108 | /* |
109 | * Allow the initialization to continue for other CPUs, if the |
110 | * reported failure is a HW misconfiguration/breakage (-ENXIO). |
111 | * |
112 | * Some platforms do not support idle operations |
113 | * (arm_cpuidle_init() returning -EOPNOTSUPP), we should |
114 | * not flag this case as an error, it is a valid |
115 | * configuration. |
116 | */ |
117 | if (ret) { |
118 | if (ret != -EOPNOTSUPP) |
119 | pr_err("CPU %d failed to init idle CPU ops\n" , cpu); |
120 | ret = ret == -ENXIO ? 0 : ret; |
121 | goto out_kfree_drv; |
122 | } |
123 | |
124 | ret = cpuidle_register(drv, NULL); |
125 | if (ret) |
126 | goto out_kfree_drv; |
127 | |
128 | cpuidle_cooling_register(drv); |
129 | |
130 | return 0; |
131 | |
132 | out_kfree_drv: |
133 | kfree(objp: drv); |
134 | return ret; |
135 | } |
136 | |
137 | /* |
138 | * arm_idle_init - Initializes arm cpuidle driver |
139 | * |
140 | * Initializes arm cpuidle driver for all CPUs, if any CPU fails |
141 | * to register cpuidle driver then rollback to cancel all CPUs |
142 | * registeration. |
143 | */ |
144 | static int __init arm_idle_init(void) |
145 | { |
146 | int cpu, ret; |
147 | struct cpuidle_driver *drv; |
148 | struct cpuidle_device *dev; |
149 | |
150 | for_each_possible_cpu(cpu) { |
151 | ret = arm_idle_init_cpu(cpu); |
152 | if (ret) |
153 | goto out_fail; |
154 | } |
155 | |
156 | return 0; |
157 | |
158 | out_fail: |
159 | while (--cpu >= 0) { |
160 | dev = per_cpu(cpuidle_devices, cpu); |
161 | drv = cpuidle_get_cpu_driver(dev); |
162 | cpuidle_unregister(drv); |
163 | kfree(objp: drv); |
164 | } |
165 | |
166 | return ret; |
167 | } |
168 | device_initcall(arm_idle_init); |
169 | |