xref: /openbmc/linux/drivers/cpuidle/cpuidle-arm.c (revision 69e26b4f)
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