// SPDX-License-Identifier: GPL-2.0-only /* * Mediated device Core Driver * * Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved. * Author: Neo Jia * Kirti Wankhede */ #include #include #include #include #include "mdev_private.h" #define DRIVER_VERSION "0.1" #define DRIVER_AUTHOR "NVIDIA Corporation" #define DRIVER_DESC "Mediated device Core Driver" static struct class_compat *mdev_bus_compat_class; static LIST_HEAD(mdev_list); static DEFINE_MUTEX(mdev_list_lock); /* Caller must hold parent unreg_sem read or write lock */ static void mdev_device_remove_common(struct mdev_device *mdev) { struct mdev_parent *parent = mdev->type->parent; mdev_remove_sysfs_files(mdev); device_del(&mdev->dev); lockdep_assert_held(&parent->unreg_sem); /* Balances with device_initialize() */ put_device(&mdev->dev); } static int mdev_device_remove_cb(struct device *dev, void *data) { if (dev->bus == &mdev_bus_type) mdev_device_remove_common(to_mdev_device(dev)); return 0; } /* * mdev_register_parent: Register a device as parent for mdevs * @parent: parent structure registered * @dev: device structure representing parent device. * @mdev_driver: Device driver to bind to the newly created mdev * @types: Array of supported mdev types * @nr_types: Number of entries in @types * * Registers the @parent stucture as a parent for mdev types and thus mdev * devices. The caller needs to hold a reference on @dev that must not be * released until after the call to mdev_unregister_parent(). * * Returns a negative value on error, otherwise 0. */ int mdev_register_parent(struct mdev_parent *parent, struct device *dev, struct mdev_driver *mdev_driver, struct mdev_type **types, unsigned int nr_types) { char *env_string = "MDEV_STATE=registered"; char *envp[] = { env_string, NULL }; int ret; memset(parent, 0, sizeof(*parent)); init_rwsem(&parent->unreg_sem); parent->dev = dev; parent->mdev_driver = mdev_driver; parent->types = types; parent->nr_types = nr_types; atomic_set(&parent->available_instances, mdev_driver->max_instances); ret = parent_create_sysfs_files(parent); if (ret) return ret; ret = class_compat_create_link(mdev_bus_compat_class, dev, NULL); if (ret) dev_warn(dev, "Failed to create compatibility class link\n"); dev_info(dev, "MDEV: Registered\n"); kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp); return 0; } EXPORT_SYMBOL(mdev_register_parent); /* * mdev_unregister_parent : Unregister a parent device * @parent: parent structure to unregister */ void mdev_unregister_parent(struct mdev_parent *parent) { char *env_string = "MDEV_STATE=unregistered"; char *envp[] = { env_string, NULL }; dev_info(parent->dev, "MDEV: Unregistering\n"); down_write(&parent->unreg_sem); class_compat_remove_link(mdev_bus_compat_class, parent->dev, NULL); device_for_each_child(parent->dev, NULL, mdev_device_remove_cb); parent_remove_sysfs_files(parent); up_write(&parent->unreg_sem); kobject_uevent_env(&parent->dev->kobj, KOBJ_CHANGE, envp); } EXPORT_SYMBOL(mdev_unregister_parent); static void mdev_device_release(struct device *dev) { struct mdev_device *mdev = to_mdev_device(dev); struct mdev_parent *parent = mdev->type->parent; mutex_lock(&mdev_list_lock); list_del(&mdev->next); if (!parent->mdev_driver->get_available) atomic_inc(&parent->available_instances); mutex_unlock(&mdev_list_lock); /* Pairs with the get in mdev_device_create() */ kobject_put(&mdev->type->kobj); dev_dbg(&mdev->dev, "MDEV: destroying\n"); kfree(mdev); } int mdev_device_create(struct mdev_type *type, const guid_t *uuid) { int ret; struct mdev_device *mdev, *tmp; struct mdev_parent *parent = type->parent; struct mdev_driver *drv = parent->mdev_driver; mutex_lock(&mdev_list_lock); /* Check for duplicate */ list_for_each_entry(tmp, &mdev_list, next) { if (guid_equal(&tmp->uuid, uuid)) { mutex_unlock(&mdev_list_lock); return -EEXIST; } } if (!drv->get_available) { /* * Note: that non-atomic read and dec is fine here because * all modifications are under mdev_list_lock. */ if (!atomic_read(&parent->available_instances)) { mutex_unlock(&mdev_list_lock); return -EUSERS; } atomic_dec(&parent->available_instances); } mdev = kzalloc(sizeof(*mdev), GFP_KERNEL); if (!mdev) { mutex_unlock(&mdev_list_lock); return -ENOMEM; } device_initialize(&mdev->dev); mdev->dev.parent = parent->dev; mdev->dev.bus = &mdev_bus_type; mdev->dev.release = mdev_device_release; mdev->dev.groups = mdev_device_groups; mdev->type = type; /* Pairs with the put in mdev_device_release() */ kobject_get(&type->kobj); guid_copy(&mdev->uuid, uuid); list_add(&mdev->next, &mdev_list); mutex_unlock(&mdev_list_lock); ret = dev_set_name(&mdev->dev, "%pUl", uuid); if (ret) goto out_put_device; /* Check if parent unregistration has started */ if (!down_read_trylock(&parent->unreg_sem)) { ret = -ENODEV; goto out_put_device; } ret = device_add(&mdev->dev); if (ret) goto out_unlock; ret = device_driver_attach(&drv->driver, &mdev->dev); if (ret) goto out_del; ret = mdev_create_sysfs_files(mdev); if (ret) goto out_del; mdev->active = true; dev_dbg(&mdev->dev, "MDEV: created\n"); up_read(&parent->unreg_sem); return 0; out_del: device_del(&mdev->dev); out_unlock: up_read(&parent->unreg_sem); out_put_device: put_device(&mdev->dev); return ret; } int mdev_device_remove(struct mdev_device *mdev) { struct mdev_device *tmp; struct mdev_parent *parent = mdev->type->parent; mutex_lock(&mdev_list_lock); list_for_each_entry(tmp, &mdev_list, next) { if (tmp == mdev) break; } if (tmp != mdev) { mutex_unlock(&mdev_list_lock); return -ENODEV; } if (!mdev->active) { mutex_unlock(&mdev_list_lock); return -EAGAIN; } mdev->active = false; mutex_unlock(&mdev_list_lock); /* Check if parent unregistration has started */ if (!down_read_trylock(&parent->unreg_sem)) return -ENODEV; mdev_device_remove_common(mdev); up_read(&parent->unreg_sem); return 0; } static int __init mdev_init(void) { int ret; ret = bus_register(&mdev_bus_type); if (ret) return ret; mdev_bus_compat_class = class_compat_register("mdev_bus"); if (!mdev_bus_compat_class) { bus_unregister(&mdev_bus_type); return -ENOMEM; } return 0; } static void __exit mdev_exit(void) { class_compat_unregister(mdev_bus_compat_class); bus_unregister(&mdev_bus_type); } subsys_initcall(mdev_init) module_exit(mdev_exit) MODULE_VERSION(DRIVER_VERSION); MODULE_LICENSE("GPL v2"); MODULE_AUTHOR(DRIVER_AUTHOR); MODULE_DESCRIPTION(DRIVER_DESC);