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
 10extern struct of_cpuidle_method __cpuidle_method_of_table[];
 11
 12static const struct of_cpuidle_method __cpuidle_method_of_table_sentinel
 13	__used __section("__cpuidle_method_of_table_end");
 14
 15static 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 */
 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 */
 45int 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 */
 61static 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 */
 86static 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 */
133int __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}