1/*
2 * Copyright 2012 Linaro Ltd.
3 *
4 * The code contained herein is licensed under the GNU General Public
5 * License. You may obtain a copy of the GNU General Public License
6 * Version 2 or later at the following locations:
7 *
8 * http://www.opensource.org/licenses/gpl-license.html
9 * http://www.gnu.org/copyleft/gpl.html
10 */
11
12#include <linux/cpuidle.h>
13#include <linux/of.h>
14#include <linux/of_device.h>
15#include <asm/cpuidle.h>
16
17extern struct of_cpuidle_method __cpuidle_method_of_table[];
18
19static const struct of_cpuidle_method __cpuidle_method_of_table_sentinel
20	__used __section(__cpuidle_method_of_table_end);
21
22static struct cpuidle_ops cpuidle_ops[NR_CPUS];
23
24/**
25 * arm_cpuidle_simple_enter() - a wrapper to cpu_do_idle()
26 * @dev: not used
27 * @drv: not used
28 * @index: not used
29 *
30 * A trivial wrapper to allow the cpu_do_idle function to be assigned as a
31 * cpuidle callback by matching the function signature.
32 *
33 * Returns the index passed as parameter
34 */
35int arm_cpuidle_simple_enter(struct cpuidle_device *dev,
36		struct cpuidle_driver *drv, int index)
37{
38	cpu_do_idle();
39
40	return index;
41}
42
43/**
44 * arm_cpuidle_suspend() - function to enter low power idle states
45 * @index: an integer used as an identifier for the low level PM callbacks
46 *
47 * This function calls the underlying arch specific low level PM code as
48 * registered at the init time.
49 *
50 * Returns -EOPNOTSUPP if no suspend callback is defined, the result of the
51 * callback otherwise.
52 */
53int arm_cpuidle_suspend(int index)
54{
55	int ret = -EOPNOTSUPP;
56	int cpu = smp_processor_id();
57
58	if (cpuidle_ops[cpu].suspend)
59		ret = cpuidle_ops[cpu].suspend(cpu, index);
60
61	return ret;
62}
63
64/**
65 * arm_cpuidle_get_ops() - find a registered cpuidle_ops by name
66 * @method: the method name
67 *
68 * Search in the __cpuidle_method_of_table array the cpuidle ops matching the
69 * method name.
70 *
71 * Returns a struct cpuidle_ops pointer, NULL if not found.
72 */
73static struct cpuidle_ops *__init arm_cpuidle_get_ops(const char *method)
74{
75	struct of_cpuidle_method *m = __cpuidle_method_of_table;
76
77	for (; m->method; m++)
78		if (!strcmp(m->method, method))
79			return m->ops;
80
81	return NULL;
82}
83
84/**
85 * arm_cpuidle_read_ops() - Initialize the cpuidle ops with the device tree
86 * @dn: a pointer to a struct device node corresponding to a cpu node
87 * @cpu: the cpu identifier
88 *
89 * Get the method name defined in the 'enable-method' property, retrieve the
90 * associated cpuidle_ops and do a struct copy. This copy is needed because all
91 * cpuidle_ops are tagged __initdata and will be unloaded after the init
92 * process.
93 *
94 * Return 0 on sucess, -ENOENT if no 'enable-method' is defined, -EOPNOTSUPP if
95 * no cpuidle_ops is registered for the 'enable-method'.
96 */
97static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu)
98{
99	const char *enable_method;
100	struct cpuidle_ops *ops;
101
102	enable_method = of_get_property(dn, "enable-method", NULL);
103	if (!enable_method)
104		return -ENOENT;
105
106	ops = arm_cpuidle_get_ops(enable_method);
107	if (!ops) {
108		pr_warn("%s: unsupported enable-method property: %s\n",
109			dn->full_name, enable_method);
110		return -EOPNOTSUPP;
111	}
112
113	cpuidle_ops[cpu] = *ops; /* structure copy */
114
115	pr_notice("cpuidle: enable-method property '%s'"
116		  " found operations\n", enable_method);
117
118	return 0;
119}
120
121/**
122 * arm_cpuidle_init() - Initialize cpuidle_ops for a specific cpu
123 * @cpu: the cpu to be initialized
124 *
125 * Initialize the cpuidle ops with the device for the cpu and then call
126 * the cpu's idle initialization callback. This may fail if the underlying HW
127 * is not operational.
128 *
129 * Returns:
130 *  0 on success,
131 *  -ENODEV if it fails to find the cpu node in the device tree,
132 *  -EOPNOTSUPP if it does not find a registered cpuidle_ops for this cpu,
133 *  -ENOENT if it fails to find an 'enable-method' property,
134 *  -ENXIO if the HW reports a failure or a misconfiguration,
135 *  -ENOMEM if the HW report an memory allocation failure
136 */
137int __init arm_cpuidle_init(int cpu)
138{
139	struct device_node *cpu_node = of_cpu_device_node_get(cpu);
140	int ret;
141
142	if (!cpu_node)
143		return -ENODEV;
144
145	ret = arm_cpuidle_read_ops(cpu_node, cpu);
146	if (!ret && cpuidle_ops[cpu].init)
147		ret = cpuidle_ops[cpu].init(cpu_node, cpu);
148
149	of_node_put(cpu_node);
150
151	return ret;
152}
153