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] __ro_after_init;
 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 the result of the suspend callback.
 51 */
 52int arm_cpuidle_suspend(int index)
 53{
 54	int cpu = smp_processor_id();
 55
 56	return cpuidle_ops[cpu].suspend(index);
 57}
 58
 59/**
 60 * arm_cpuidle_get_ops() - find a registered cpuidle_ops by name
 61 * @method: the method name
 62 *
 63 * Search in the __cpuidle_method_of_table array the cpuidle ops matching the
 64 * method name.
 65 *
 66 * Returns a struct cpuidle_ops pointer, NULL if not found.
 67 */
 68static const struct cpuidle_ops *__init arm_cpuidle_get_ops(const char *method)
 69{
 70	struct of_cpuidle_method *m = __cpuidle_method_of_table;
 71
 72	for (; m->method; m++)
 73		if (!strcmp(m->method, method))
 74			return m->ops;
 75
 76	return NULL;
 77}
 78
 79/**
 80 * arm_cpuidle_read_ops() - Initialize the cpuidle ops with the device tree
 81 * @dn: a pointer to a struct device node corresponding to a cpu node
 82 * @cpu: the cpu identifier
 83 *
 84 * Get the method name defined in the 'enable-method' property, retrieve the
 85 * associated cpuidle_ops and do a struct copy. This copy is needed because all
 86 * cpuidle_ops are tagged __initconst and will be unloaded after the init
 87 * process.
 88 *
 89 * Return 0 on sucess, -ENOENT if no 'enable-method' is defined, -EOPNOTSUPP if
 90 * no cpuidle_ops is registered for the 'enable-method', or if either init or
 91 * suspend callback isn't defined.
 92 */
 93static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu)
 94{
 95	const char *enable_method;
 96	const struct cpuidle_ops *ops;
 97
 98	enable_method = of_get_property(dn, "enable-method", NULL);
 99	if (!enable_method)
100		return -ENOENT;
101
102	ops = arm_cpuidle_get_ops(enable_method);
103	if (!ops) {
104		pr_warn("%pOF: unsupported enable-method property: %s\n",
105			dn, enable_method);
106		return -EOPNOTSUPP;
107	}
108
109	if (!ops->init || !ops->suspend) {
110		pr_warn("cpuidle_ops '%s': no init or suspend callback\n",
111			enable_method);
112		return -EOPNOTSUPP;
113	}
114
115	cpuidle_ops[cpu] = *ops; /* structure copy */
116
117	pr_notice("cpuidle: enable-method property '%s'"
118		  " found operations\n", enable_method);
119
120	return 0;
121}
122
123/**
124 * arm_cpuidle_init() - Initialize cpuidle_ops for a specific cpu
125 * @cpu: the cpu to be initialized
126 *
127 * Initialize the cpuidle ops with the device for the cpu and then call
128 * the cpu's idle initialization callback. This may fail if the underlying HW
129 * is not operational.
130 *
131 * Returns:
132 *  0 on success,
133 *  -ENODEV if it fails to find the cpu node in the device tree,
134 *  -EOPNOTSUPP if it does not find a registered and valid cpuidle_ops for
135 *  this cpu,
136 *  -ENOENT if it fails to find an 'enable-method' property,
137 *  -ENXIO if the HW reports a failure or a misconfiguration,
138 *  -ENOMEM if the HW report an memory allocation failure 
139 */
140int __init arm_cpuidle_init(int cpu)
141{
142	struct device_node *cpu_node = of_cpu_device_node_get(cpu);
143	int ret;
144
145	if (!cpu_node)
146		return -ENODEV;
147
148	ret = arm_cpuidle_read_ops(cpu_node, cpu);
149	if (!ret)
150		ret = cpuidle_ops[cpu].init(cpu_node, cpu);
151
152	of_node_put(cpu_node);
153
154	return ret;
155}