1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright 2012 Linaro Ltd.
4 */
5
6 #include <linux/cpuidle.h>
7 #include <linux/of.h>
8 #include <linux/of_device.h>
9 #include <asm/cpuidle.h>
10
11 extern struct of_cpuidle_method __cpuidle_method_of_table[];
12
13 static const struct of_cpuidle_method __cpuidle_method_of_table_sentinel
14 __used __section("__cpuidle_method_of_table_end");
15
16 static struct cpuidle_ops cpuidle_ops[NR_CPUS] __ro_after_init;
17
18 /**
19 * arm_cpuidle_simple_enter() - a wrapper to cpu_do_idle()
20 * @dev: not used
21 * @drv: not used
22 * @index: not used
23 *
24 * A trivial wrapper to allow the cpu_do_idle function to be assigned as a
25 * cpuidle callback by matching the function signature.
26 *
27 * Returns the index passed as parameter
28 */
arm_cpuidle_simple_enter(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)29 int arm_cpuidle_simple_enter(struct cpuidle_device *dev,
30 struct cpuidle_driver *drv, int index)
31 {
32 cpu_do_idle();
33
34 return index;
35 }
36
37 /**
38 * arm_cpuidle_suspend() - function to enter low power idle states
39 * @index: an integer used as an identifier for the low level PM callbacks
40 *
41 * This function calls the underlying arch specific low level PM code as
42 * registered at the init time.
43 *
44 * Returns the result of the suspend callback.
45 */
arm_cpuidle_suspend(int index)46 int arm_cpuidle_suspend(int index)
47 {
48 int cpu = smp_processor_id();
49
50 return cpuidle_ops[cpu].suspend(index);
51 }
52
53 /**
54 * arm_cpuidle_get_ops() - find a registered cpuidle_ops by name
55 * @method: the method name
56 *
57 * Search in the __cpuidle_method_of_table array the cpuidle ops matching the
58 * method name.
59 *
60 * Returns a struct cpuidle_ops pointer, NULL if not found.
61 */
arm_cpuidle_get_ops(const char * method)62 static const struct cpuidle_ops *__init arm_cpuidle_get_ops(const char *method)
63 {
64 struct of_cpuidle_method *m = __cpuidle_method_of_table;
65
66 for (; m->method; m++)
67 if (!strcmp(m->method, method))
68 return m->ops;
69
70 return NULL;
71 }
72
73 /**
74 * arm_cpuidle_read_ops() - Initialize the cpuidle ops with the device tree
75 * @dn: a pointer to a struct device node corresponding to a cpu node
76 * @cpu: the cpu identifier
77 *
78 * Get the method name defined in the 'enable-method' property, retrieve the
79 * associated cpuidle_ops and do a struct copy. This copy is needed because all
80 * cpuidle_ops are tagged __initconst and will be unloaded after the init
81 * process.
82 *
83 * Return 0 on sucess, -ENOENT if no 'enable-method' is defined, -EOPNOTSUPP if
84 * no cpuidle_ops is registered for the 'enable-method', or if either init or
85 * suspend callback isn't defined.
86 */
arm_cpuidle_read_ops(struct device_node * dn,int cpu)87 static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu)
88 {
89 const char *enable_method;
90 const struct cpuidle_ops *ops;
91
92 enable_method = of_get_property(dn, "enable-method", NULL);
93 if (!enable_method)
94 return -ENOENT;
95
96 ops = arm_cpuidle_get_ops(enable_method);
97 if (!ops) {
98 pr_warn("%pOF: unsupported enable-method property: %s\n",
99 dn, enable_method);
100 return -EOPNOTSUPP;
101 }
102
103 if (!ops->init || !ops->suspend) {
104 pr_warn("cpuidle_ops '%s': no init or suspend callback\n",
105 enable_method);
106 return -EOPNOTSUPP;
107 }
108
109 cpuidle_ops[cpu] = *ops; /* structure copy */
110
111 pr_notice("cpuidle: enable-method property '%s'"
112 " found operations\n", enable_method);
113
114 return 0;
115 }
116
117 /**
118 * arm_cpuidle_init() - Initialize cpuidle_ops for a specific cpu
119 * @cpu: the cpu to be initialized
120 *
121 * Initialize the cpuidle ops with the device for the cpu and then call
122 * the cpu's idle initialization callback. This may fail if the underlying HW
123 * is not operational.
124 *
125 * Returns:
126 * 0 on success,
127 * -ENODEV if it fails to find the cpu node in the device tree,
128 * -EOPNOTSUPP if it does not find a registered and valid cpuidle_ops for
129 * this cpu,
130 * -ENOENT if it fails to find an 'enable-method' property,
131 * -ENXIO if the HW reports a failure or a misconfiguration,
132 * -ENOMEM if the HW report an memory allocation failure
133 */
arm_cpuidle_init(int cpu)134 int __init arm_cpuidle_init(int cpu)
135 {
136 struct device_node *cpu_node = of_cpu_device_node_get(cpu);
137 int ret;
138
139 if (!cpu_node)
140 return -ENODEV;
141
142 ret = arm_cpuidle_read_ops(cpu_node, cpu);
143 if (!ret)
144 ret = cpuidle_ops[cpu].init(cpu_node, cpu);
145
146 of_node_put(cpu_node);
147
148 return ret;
149 }
150