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