69 lines
1.7 KiB
C
69 lines
1.7 KiB
C
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/*
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* drivers/base/power/sysfs.c - sysfs entries for device PM
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*/
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#include <linux/device.h>
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#include "power.h"
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/**
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* state - Control current power state of device
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*
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* show() returns the current power state of the device. '0' indicates
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* the device is on. Other values (1-3) indicate the device is in a low
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* power state.
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*
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* store() sets the current power state, which is an integer value
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* between 0-3. If the device is on ('0'), and the value written is
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* greater than 0, then the device is placed directly into the low-power
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* state (via its driver's ->suspend() method).
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* If the device is currently in a low-power state, and the value is 0,
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* the device is powered back on (via the ->resume() method).
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* If the device is in a low-power state, and a different low-power state
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* is requested, the device is first resumed, then suspended into the new
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* low-power state.
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*/
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static ssize_t state_show(struct device * dev, char * buf)
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{
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return sprintf(buf, "%u\n", dev->power.power_state);
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}
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static ssize_t state_store(struct device * dev, const char * buf, size_t n)
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{
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u32 state;
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char * rest;
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int error = 0;
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state = simple_strtoul(buf, &rest, 10);
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if (*rest)
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return -EINVAL;
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if (state)
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error = dpm_runtime_suspend(dev, state);
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else
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dpm_runtime_resume(dev);
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return error ? error : n;
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}
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static DEVICE_ATTR(state, 0644, state_show, state_store);
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static struct attribute * power_attrs[] = {
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&dev_attr_state.attr,
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NULL,
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};
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static struct attribute_group pm_attr_group = {
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.name = "power",
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.attrs = power_attrs,
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};
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int dpm_sysfs_add(struct device * dev)
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{
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return sysfs_create_group(&dev->kobj, &pm_attr_group);
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}
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void dpm_sysfs_remove(struct device * dev)
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{
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sysfs_remove_group(&dev->kobj, &pm_attr_group);
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}
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