diff options
Diffstat (limited to 'drivers/base/core.c')
| -rw-r--r-- | drivers/base/core.c | 146 |
1 files changed, 139 insertions, 7 deletions
diff --git a/drivers/base/core.c b/drivers/base/core.c index 2499cef..dc3ea23 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -193,12 +193,12 @@ ssize_t device_show_bool(struct device *dev, struct device_attribute *attr, EXPORT_SYMBOL_GPL(device_show_bool); /** - * device_release - free device structure. - * @kobj: device's kobject. + * device_release - free device structure. + * @kobj: device's kobject. * - * This is called once the reference count for the object - * reaches 0. We forward the call to the device's release - * method, which should handle actually freeing the structure. + * This is called once the reference count for the object + * reaches 0. We forward the call to the device's release + * method, which should handle actually freeing the structure. */ static void device_release(struct kobject *kobj) { @@ -403,6 +403,36 @@ static ssize_t store_uevent(struct device *dev, struct device_attribute *attr, static struct device_attribute uevent_attr = __ATTR(uevent, S_IRUGO | S_IWUSR, show_uevent, store_uevent); +static ssize_t show_online(struct device *dev, struct device_attribute *attr, + char *buf) +{ + bool val; + + lock_device_hotplug(); + val = !dev->offline; + unlock_device_hotplug(); + return sprintf(buf, "%u\n", val); +} + +static ssize_t store_online(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + bool val; + int ret; + + ret = strtobool(buf, &val); + if (ret < 0) + return ret; + + lock_device_hotplug(); + ret = val ? device_online(dev) : device_offline(dev); + unlock_device_hotplug(); + return ret < 0 ? ret : count; +} + +static struct device_attribute online_attr = + __ATTR(online, S_IRUGO | S_IWUSR, show_online, store_online); + static int device_add_attributes(struct device *dev, struct device_attribute *attrs) { @@ -516,6 +546,12 @@ static int device_add_attrs(struct device *dev) if (error) goto err_remove_type_groups; + if (device_supports_offline(dev) && !dev->offline_disabled) { + error = device_create_file(dev, &online_attr); + if (error) + goto err_remove_type_groups; + } + return 0; err_remove_type_groups: @@ -536,6 +572,7 @@ static void device_remove_attrs(struct device *dev) struct class *class = dev->class; const struct device_type *type = dev->type; + device_remove_file(dev, &online_attr); device_remove_groups(dev, dev->groups); if (type) @@ -1334,8 +1371,8 @@ const char *device_get_devnode(struct device *dev, /** * device_for_each_child - device child iterator. * @parent: parent struct device. - * @data: data for the callback. * @fn: function to be called for each device. + * @data: data for the callback. * * Iterate over @parent's child devices, and call @fn for each, * passing it @data. @@ -1363,8 +1400,8 @@ int device_for_each_child(struct device *parent, void *data, /** * device_find_child - device iterator for locating a particular device. * @parent: parent struct device - * @data: Data to pass to match function * @match: Callback function to check device + * @data: Data to pass to match function * * This is similar to the device_for_each_child() function above, but it * returns a reference to a device that is 'found' for later use, as @@ -1374,6 +1411,8 @@ int device_for_each_child(struct device *parent, void *data, * if it does. If the callback returns non-zero and a reference to the * current device can be obtained, this function will return to the caller * and not iterate over any more devices. + * + * NOTE: you will need to drop the reference with put_device() after use. */ struct device *device_find_child(struct device *parent, void *data, int (*match)(struct device *dev, void *data)) @@ -1433,6 +1472,99 @@ EXPORT_SYMBOL_GPL(put_device); EXPORT_SYMBOL_GPL(device_create_file); EXPORT_SYMBOL_GPL(device_remove_file); +static DEFINE_MUTEX(device_hotplug_lock); + +void lock_device_hotplug(void) +{ + mutex_lock(&device_hotplug_lock); +} + +void unlock_device_hotplug(void) +{ + mutex_unlock(&device_hotplug_lock); +} + +static int device_check_offline(struct device *dev, void *not_used) +{ + int ret; + + ret = device_for_each_child(dev, NULL, device_check_offline); + if (ret) + return ret; + + return device_supports_offline(dev) && !dev->offline ? -EBUSY : 0; +} + +/** + * device_offline - Prepare the device for hot-removal. + * @dev: Device to be put offline. + * + * Execute the device bus type's .offline() callback, if present, to prepare + * the device for a subsequent hot-removal. If that succeeds, the device must + * not be used until either it is removed or its bus type's .online() callback + * is executed. + * + * Call under device_hotplug_lock. + */ +int device_offline(struct device *dev) +{ + int ret; + + if (dev->offline_disabled) + return -EPERM; + + ret = device_for_each_child(dev, NULL, device_check_offline); + if (ret) + return ret; + + device_lock(dev); + if (device_supports_offline(dev)) { + if (dev->offline) { + ret = 1; + } else { + ret = dev->bus->offline(dev); + if (!ret) { + kobject_uevent(&dev->kobj, KOBJ_OFFLINE); + dev->offline = true; + } + } + } + device_unlock(dev); + + return ret; +} + +/** + * device_online - Put the device back online after successful device_offline(). + * @dev: Device to be put back online. + * + * If device_offline() has been successfully executed for @dev, but the device + * has not been removed subsequently, execute its bus type's .online() callback + * to indicate that the device can be used again. + * + * Call under device_hotplug_lock. + */ +int device_online(struct device *dev) +{ + int ret = 0; + + device_lock(dev); + if (device_supports_offline(dev)) { + if (dev->offline) { + ret = dev->bus->online(dev); + if (!ret) { + kobject_uevent(&dev->kobj, KOBJ_ONLINE); + dev->offline = false; + } + } else { + ret = 1; + } + } + device_unlock(dev); + + return ret; +} + struct root_device { struct device dev; struct module *owner; |