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/*
* Copyright 2012 Linaro Ltd.
*
* The code contained herein is licensed under the GNU General Public
* License. You may obtain a copy of the GNU General Public License
* Version 2 or later at the following locations:
*
* http://www.opensource.org/licenses/gpl-license.html
* http://www.gnu.org/copyleft/gpl.html
*/
#include <linux/cpuidle.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <asm/cpuidle.h>
extern struct of_cpuidle_method __cpuidle_method_of_table[];
static const struct of_cpuidle_method __cpuidle_method_of_table_sentinel
__used __section(__cpuidle_method_of_table_end);
static struct cpuidle_ops cpuidle_ops[NR_CPUS] __ro_after_init;
/**
* arm_cpuidle_simple_enter() - a wrapper to cpu_do_idle()
* @dev: not used
* @drv: not used
* @index: not used
*
* A trivial wrapper to allow the cpu_do_idle function to be assigned as a
* cpuidle callback by matching the function signature.
*
* Returns the index passed as parameter
*/
int arm_cpuidle_simple_enter(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int index)
{
cpu_do_idle();
return index;
}
/**
* arm_cpuidle_suspend() - function to enter low power idle states
* @index: an integer used as an identifier for the low level PM callbacks
*
* This function calls the underlying arch specific low level PM code as
* registered at the init time.
*
* Returns the result of the suspend callback.
*/
int arm_cpuidle_suspend(int index)
{
int cpu = smp_processor_id();
return cpuidle_ops[cpu].suspend(index);
}
/**
* arm_cpuidle_get_ops() - find a registered cpuidle_ops by name
* @method: the method name
*
* Search in the __cpuidle_method_of_table array the cpuidle ops matching the
* method name.
*
* Returns a struct cpuidle_ops pointer, NULL if not found.
*/
static const struct cpuidle_ops *__init arm_cpuidle_get_ops(const char *method)
{
struct of_cpuidle_method *m = __cpuidle_method_of_table;
for (; m->method; m++)
if (!strcmp(m->method, method))
return m->ops;
return NULL;
}
/**
* arm_cpuidle_read_ops() - Initialize the cpuidle ops with the device tree
* @dn: a pointer to a struct device node corresponding to a cpu node
* @cpu: the cpu identifier
*
* Get the method name defined in the 'enable-method' property, retrieve the
* associated cpuidle_ops and do a struct copy. This copy is needed because all
* cpuidle_ops are tagged __initconst and will be unloaded after the init
* process.
*
* Return 0 on sucess, -ENOENT if no 'enable-method' is defined, -EOPNOTSUPP if
* no cpuidle_ops is registered for the 'enable-method', or if either init or
* suspend callback isn't defined.
*/
static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu)
{
const char *enable_method;
const struct cpuidle_ops *ops;
enable_method = of_get_property(dn, "enable-method", NULL);
if (!enable_method)
return -ENOENT;
ops = arm_cpuidle_get_ops(enable_method);
if (!ops) {
pr_warn("%s: unsupported enable-method property: %s\n",
dn->full_name, enable_method);
return -EOPNOTSUPP;
}
if (!ops->init || !ops->suspend) {
pr_warn("cpuidle_ops '%s': no init or suspend callback\n",
enable_method);
return -EOPNOTSUPP;
}
cpuidle_ops[cpu] = *ops; /* structure copy */
pr_notice("cpuidle: enable-method property '%s'"
" found operations\n", enable_method);
return 0;
}
/**
* arm_cpuidle_init() - Initialize cpuidle_ops for a specific cpu
* @cpu: the cpu to be initialized
*
* Initialize the cpuidle ops with the device for the cpu and then call
* the cpu's idle initialization callback. This may fail if the underlying HW
* is not operational.
*
* Returns:
* 0 on success,
* -ENODEV if it fails to find the cpu node in the device tree,
* -EOPNOTSUPP if it does not find a registered and valid cpuidle_ops for
* this cpu,
* -ENOENT if it fails to find an 'enable-method' property,
* -ENXIO if the HW reports a failure or a misconfiguration,
* -ENOMEM if the HW report an memory allocation failure
*/
int __init arm_cpuidle_init(int cpu)
{
struct device_node *cpu_node = of_cpu_device_node_get(cpu);
int ret;
if (!cpu_node)
return -ENODEV;
ret = arm_cpuidle_read_ops(cpu_node, cpu);
if (!ret)
ret = cpuidle_ops[cpu].init(cpu_node, cpu);
of_node_put(cpu_node);
return ret;
}
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