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
 11extern struct of_cpuidle_method __cpuidle_method_of_table[];
 12
 13static const struct of_cpuidle_method __cpuidle_method_of_table_sentinel
 14	__used __section(__cpuidle_method_of_table_end);
 15
 16static 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 */
 29int 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 */
 46int 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 */
 62static 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 */
 87static 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 */
134int __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}