Power Management in the Linux Driver Model(2.6.14)(转)

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2008-07-11 10:51

Power Management in the Linux Driver Model(2.6.14)

--for device_add()

/**
*    device_add - add device to device hierarchy.
*    @dev:    device.
*
*    This is part 2 of device_register(), though may be called
*    separately _iff_ device_initialize() has been called separately.
*
*    This adds it to the kobject hierarchy via kobject_add(), adds it
*    to the global and sibling lists for the device, then
*    adds it to the other relevant subsystems of the driver model.
*/
int device_add(struct device *dev)
{
    struct device *parent = NULL;
    int error = -EINVAL;

    dev = get_device(dev);
    if (!dev || !strlen(dev->bus_id))
        goto Error;

    parent = get_device(dev->parent);

    pr_debug("DEV: registering device: ID = '%s'\n", dev->bus_id);

    /* first, register with generic layer. */
    kobject_set_name(&dev->kobj, "%s", dev->bus_id);
    if (parent)
        dev->kobj.parent = &parent->kobj;

    if ((error = kobject_add(&dev->kobj)))
        goto Error;
    kobject_hotplug(&dev->kobj, KOBJ_ADD);
    if ((error = device_pm_add(dev)))
        goto PMError;
    if ((error = bus_add_device(dev)))
        goto BusError;
    if (parent)
        klist_add_tail(&dev->knode_parent, &parent->klist_children);

    /* notify platform of device entry */
    if (platform_notify)
        platform_notify(dev);
Done:
    put_device(dev);
    return error;
BusError:
    device_pm_remove(dev);
PMError:
    kobject_hotplug(&dev->kobj, KOBJ_REMOVE);
    kobject_del(&dev->kobj);
Error:
    if (parent)
        put_device(parent);
    goto Done;
}

int device_pm_add(struct device * dev)
{
    int error;

    pr_debug("PM: Adding info for %s:%s\n",
        dev->bus ? dev->bus->name : "No Bus", dev->kobj.name);
    atomic_set(&dev->power.pm_users, 0);
    down(&dpm_list_sem);
    list_add_tail(&dev->power.entry, &dpm_active);
    device_pm_set_parent(dev, dev->parent);
    if ((error = dpm_sysfs_add(dev)))
        list_del(&dev->power.entry);
    up(&dpm_list_sem);
    return error;
}

/**
*    device_pm_set_parent - Specify power dependency.
*    @dev:        Device who needs power.
*    @parent:    Device that supplies power.
*
*    This function is used to manually describe a power-dependency
*    relationship. It may be used to specify a transversal relationship
*    (where the power supplier is not the physical (or electrical)
*    ancestor of a specific device.
*    The effect of this is that the supplier will not be powered down
*    before the power dependent.
*/

void device_pm_set_parent(struct device * dev, struct device * parent)
{
    struct device * old_parent = dev->power.pm_parent;
    device_pm_release(old_parent);
    dev->power.pm_parent = parent;
    device_pm_hold(parent);
}

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