// SPDX-License-Identifier: GPL-2.0/* * driver.c - centralized device driver management * * Copyright (c) 2002-3 Patrick Mochel * Copyright (c) 2002-3 Open Source Development Labs * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de> * Copyright (c) 2007 Novell Inc. */ #include <linux/device/driver.h>#include <linux/device.h>#include <linux/module.h>#include <linux/errno.h>#include <linux/slab.h>#include <linux/string.h>#include <linux/sysfs.h>#include "base.h" static struct device *next_device(struct klist_iter *i){	struct klist_node *n = klist_next(i);	struct device *dev = NULL;	struct device_private *dev_prv; 	if (n) {		dev_prv = to_device_private_driver(n);		dev = dev_prv->device;	}	return dev;} /** * driver_set_override() - Helper to set or clear driver override. * @dev: Device to change * @override: Address of string to change (e.g. &device->driver_override); *            The contents will be freed and hold newly allocated override. * @s: NUL-terminated string, new driver name to force a match, pass empty *     string to clear it ("" or "\n", where the latter is only for sysfs *     interface). * @len: length of @s * * Helper to set or clear driver override in a device, intended for the cases * when the driver_override field is allocated by driver/bus code. * * Returns: 0 on success or a negative error code on failure. */int driver_set_override(struct device *dev, const char **override,			const char *s, size_t len){	const char *new, *old;	char *cp; 	if (!override || !s)		return -EINVAL; 	/*	 * The stored value will be used in sysfs show callback (sysfs_emit()),	 * which has a length limit of PAGE_SIZE and adds a trailing newline.	 * Thus we can store one character less to avoid truncation during sysfs	 * show.	 */	if (len >= (PAGE_SIZE - 1))		return -EINVAL; 	/*	 * Compute the real length of the string in case userspace sends us a	 * bunch of \0 characters like python likes to do.	 */	len = strlen(s); 	if (!len) {		/* Empty string passed - clear override */		device_lock(dev);		old = *override;		*override = NULL;		device_unlock(dev);		kfree(old); 		return 0;	} 	cp = strnchr(s, len, '\n');	if (cp)		len = cp - s; 	new = kstrndup(s, len, GFP_KERNEL);	if (!new)		return -ENOMEM; 	device_lock(dev);	old = *override;	if (cp != s) {		*override = new;	} else {		/* "\n" passed - clear override */		kfree(new);		*override = NULL;	}	device_unlock(dev); 	kfree(old); 	return 0;}EXPORT_SYMBOL_GPL(driver_set_override); /** * driver_for_each_device - Iterator for devices bound to a driver. * @drv: Driver we're iterating. * @start: Device to begin with * @data: Data to pass to the callback. * @fn: Function to call for each device. * * Iterate over the @drv's list of devices calling @fn for each one. */int driver_for_each_device(struct device_driver *drv, struct device *start,			   void *data, int (*fn)(struct device *, void *)){	struct klist_iter i;	struct device *dev;	int error = 0; 	if (!drv)		return -EINVAL; 	klist_iter_init_node(&drv->p->klist_devices, &i,			     start ? &start->p->knode_driver : NULL);	while (!error && (dev = next_device(&i)))		error = fn(dev, data);	klist_iter_exit(&i);	return error;}EXPORT_SYMBOL_GPL(driver_for_each_device); /** * driver_find_device - device iterator for locating a particular device. * @drv: The device's driver * @start: Device to begin with * @data: Data to pass to match function * @match: Callback function to check device * * This is similar to the driver_for_each_device() 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. */struct device *driver_find_device(struct device_driver *drv,				  struct device *start, const void *data,				  int (*match)(struct device *dev, const void *data)){	struct klist_iter i;	struct device *dev; 	if (!drv || !drv->p)		return NULL; 	klist_iter_init_node(&drv->p->klist_devices, &i,			     (start ? &start->p->knode_driver : NULL));	while ((dev = next_device(&i)))		if (match(dev, data) && get_device(dev))			break;	klist_iter_exit(&i);	return dev;}EXPORT_SYMBOL_GPL(driver_find_device); /** * driver_create_file - create sysfs file for driver. * @drv: driver. * @attr: driver attribute descriptor. */int driver_create_file(struct device_driver *drv,		       const struct driver_attribute *attr){	int error; 	if (drv)		error = sysfs_create_file(&drv->p->kobj, &attr->attr);	else		error = -EINVAL;	return error;}EXPORT_SYMBOL_GPL(driver_create_file); /** * driver_remove_file - remove sysfs file for driver. * @drv: driver. * @attr: driver attribute descriptor. */void driver_remove_file(struct device_driver *drv,			const struct driver_attribute *attr){	if (drv)		sysfs_remove_file(&drv->p->kobj, &attr->attr);}EXPORT_SYMBOL_GPL(driver_remove_file); int driver_add_groups(struct device_driver *drv,		      const struct attribute_group **groups){	return sysfs_create_groups(&drv->p->kobj, groups);} void driver_remove_groups(struct device_driver *drv,			  const struct attribute_group **groups){	sysfs_remove_groups(&drv->p->kobj, groups);} /** * driver_register - register driver with bus * @drv: driver to register * * We pass off most of the work to the bus_add_driver() call, * since most of the things we have to do deal with the bus * structures. */int driver_register(struct device_driver *drv){	int ret;	struct device_driver *other; 	if (!bus_is_registered(drv->bus)) {		pr_err("Driver '%s' was unable to register with bus_type '%s' because the bus was not initialized.\n",			   drv->name, drv->bus->name);		return -EINVAL;	} 	if ((drv->bus->probe && drv->probe) ||	    (drv->bus->remove && drv->remove) ||	    (drv->bus->shutdown && drv->shutdown))		pr_warn("Driver '%s' needs updating - please use "			"bus_type methods\n", drv->name); 	other = driver_find(drv->name, drv->bus);	if (other) {		pr_err("Error: Driver '%s' is already registered, "			"aborting...\n", drv->name);		return -EBUSY;	} 	ret = bus_add_driver(drv);	if (ret)		return ret;	ret = driver_add_groups(drv, drv->groups);	if (ret) {		bus_remove_driver(drv);		return ret;	}	kobject_uevent(&drv->p->kobj, KOBJ_ADD);	deferred_probe_extend_timeout(); 	return ret;}EXPORT_SYMBOL_GPL(driver_register); /** * driver_unregister - remove driver from system. * @drv: driver. * * Again, we pass off most of the work to the bus-level call. */void driver_unregister(struct device_driver *drv){	if (!drv || !drv->p) {		WARN(1, "Unexpected driver unregister!\n");		return;	}	driver_remove_groups(drv, drv->groups);	bus_remove_driver(drv);}EXPORT_SYMBOL_GPL(driver_unregister);