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- // 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 <[email protected]>
- * 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 (!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);
- 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);
- /**
- * 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);
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