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 */
arm_enter_idle_state(struct cpuidle_device * dev,struct cpuidle_driver * drv,int idx)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 */
arm_idle_init_cpu(int cpu)78 static int __init arm_idle_init_cpu(int cpu)
79 {
80 int ret;
81 struct cpuidle_driver *drv;
82
83 drv = kmemdup(&arm_idle_driver, 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, arm_idle_state_match, 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(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 */
arm_idle_init(void)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(drv);
164 }
165
166 return ret;
167 }
168 device_initcall(arm_idle_init);
169