| // 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; |
| |
| 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 (!drv->bus->p) { |
| 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); |
| |
| 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); |
| |
| /** |
| * driver_find - locate driver on a bus by its name. |
| * @name: name of the driver. |
| * @bus: bus to scan for the driver. |
| * |
| * Call kset_find_obj() to iterate over list of drivers on |
| * a bus to find driver by name. Return driver if found. |
| * |
| * This routine provides no locking to prevent the driver it returns |
| * from being unregistered or unloaded while the caller is using it. |
| * The caller is responsible for preventing this. |
| */ |
| struct device_driver *driver_find(const char *name, struct bus_type *bus) |
| { |
| struct kobject *k = kset_find_obj(bus->p->drivers_kset, name); |
| struct driver_private *priv; |
| |
| if (k) { |
| /* Drop reference added by kset_find_obj() */ |
| kobject_put(k); |
| priv = to_driver(k); |
| return priv->driver; |
| } |
| return NULL; |
| } |
| EXPORT_SYMBOL_GPL(driver_find); |