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(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}