diff options
Diffstat (limited to 'drivers/base/class.c')
| -rw-r--r-- | drivers/base/class.c | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/drivers/base/class.c b/drivers/base/class.c index b962a76875d2..9f737ff0fc71 100644 --- a/drivers/base/class.c +++ b/drivers/base/class.c @@ -809,6 +809,139 @@ void class_device_put(struct class_device *class_dev) kobject_put(&class_dev->kobj); } +/** + * class_for_each_device - device iterator + * @class: the class we're iterating + * @data: data for the callback + * @fn: function to be called for each device + * + * Iterate over @class's list of devices, and call @fn for each, + * passing it @data. + * + * We check the return of @fn each time. If it returns anything + * other than 0, we break out and return that value. + * + * Note, we hold class->sem in this function, so it can not be + * re-acquired in @fn, otherwise it will self-deadlocking. For + * example, calls to add or remove class members would be verboten. + */ +int class_for_each_device(struct class *class, void *data, + int (*fn)(struct device *, void *)) +{ + struct device *dev; + int error = 0; + + if (!class) + return -EINVAL; + down(&class->sem); + list_for_each_entry(dev, &class->devices, node) { + dev = get_device(dev); + if (dev) { + error = fn(dev, data); + put_device(dev); + } else + error = -ENODEV; + if (error) + break; + } + up(&class->sem); + + return error; +} +EXPORT_SYMBOL_GPL(class_for_each_device); + +/** + * class_find_device - device iterator for locating a particular device + * @class: the class we're iterating + * @data: data for the match function + * @match: function to check device + * + * This is similar to the class_for_each_dev() function above, but it + * returns a reference to a device that is 'found' for later use, as + * determined by the @match callback. + * + * The callback should return 0 if the device doesn't match and non-zero + * if it does. If the callback returns non-zero, 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. + * + * We hold class->sem in this function, so it can not be + * re-acquired in @match, otherwise it will self-deadlocking. For + * example, calls to add or remove class members would be verboten. + */ +struct device *class_find_device(struct class *class, void *data, + int (*match)(struct device *, void *)) +{ + struct device *dev; + int found = 0; + + if (!class) + return NULL; + + down(&class->sem); + list_for_each_entry(dev, &class->devices, node) { + dev = get_device(dev); + if (dev) { + if (match(dev, data)) { + found = 1; + break; + } else + put_device(dev); + } else + break; + } + up(&class->sem); + + return found ? dev : NULL; +} +EXPORT_SYMBOL_GPL(class_find_device); + +/** + * class_find_child - device iterator for locating a particular class_device + * @class: the class we're iterating + * @data: data for the match function + * @match: function to check class_device + * + * This function returns a reference to a class_device that is 'found' for + * later use, as determined by the @match callback. + * + * The callback should return 0 if the class_device doesn't match and non-zero + * if it does. If the callback returns non-zero, this function will + * return to the caller and not iterate over any more class_devices. + * + * Note, you will need to drop the reference with class_device_put() after use. + * + * We hold class->sem in this function, so it can not be + * re-acquired in @match, otherwise it will self-deadlocking. For + * example, calls to add or remove class members would be verboten. + */ +struct class_device *class_find_child(struct class *class, void *data, + int (*match)(struct class_device *, void *)) +{ + struct class_device *dev; + int found = 0; + + if (!class) + return NULL; + + down(&class->sem); + list_for_each_entry(dev, &class->children, node) { + dev = class_device_get(dev); + if (dev) { + if (match(dev, data)) { + found = 1; + break; + } else + class_device_put(dev); + } else + break; + } + up(&class->sem); + + return found ? dev : NULL; +} +EXPORT_SYMBOL_GPL(class_find_child); int class_interface_register(struct class_interface *class_intf) { |