// 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_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);