diff options
Diffstat (limited to 'drivers/base/power/main.c')
| -rw-r--r-- | drivers/base/power/main.c | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c new file mode 100644 index 000000000000..15e6a8f951f1 --- /dev/null +++ b/drivers/base/power/main.c @@ -0,0 +1,99 @@ +/* + * drivers/base/power/main.c - Where the driver meets power management. + * + * Copyright (c) 2003 Patrick Mochel + * Copyright (c) 2003 Open Source Development Lab + * + * This file is released under the GPLv2 + * + * + * The driver model core calls device_pm_add() when a device is registered. + * This will intialize the embedded device_pm_info object in the device + * and add it to the list of power-controlled devices. sysfs entries for + * controlling device power management will also be added. + * + * A different set of lists than the global subsystem list are used to + * keep track of power info because we use different lists to hold + * devices based on what stage of the power management process they + * are in. The power domain dependencies may also differ from the + * ancestral dependencies that the subsystem list maintains. + */ + +#include <linux/config.h> +#include <linux/device.h> +#include "power.h" + +LIST_HEAD(dpm_active); +LIST_HEAD(dpm_off); +LIST_HEAD(dpm_off_irq); + +DECLARE_MUTEX(dpm_sem); +DECLARE_MUTEX(dpm_list_sem); + +/* + * PM Reference Counting. + */ + +static inline void device_pm_hold(struct device * dev) +{ + if (dev) + atomic_inc(&dev->power.pm_users); +} + +static inline void device_pm_release(struct device * dev) +{ + if (dev) + atomic_dec(&dev->power.pm_users); +} + + +/** + * 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); +} +EXPORT_SYMBOL_GPL(device_pm_set_parent); + +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; +} + +void device_pm_remove(struct device * dev) +{ + pr_debug("PM: Removing info for %s:%s\n", + dev->bus ? dev->bus->name : "No Bus", dev->kobj.name); + down(&dpm_list_sem); + dpm_sysfs_remove(dev); + device_pm_release(dev->power.pm_parent); + list_del_init(&dev->power.entry); + up(&dpm_list_sem); +} + + |