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