media/v4l2-core/v4l2-device.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003     V4L2 device support.
0004
0005     Copyright (C) 2008  Hans Verkuil <hverkuil@xs4all.nl>
0006
0007  */
0008
0009 #include <linux/types.h>
0010 #include <linux/ioctl.h>
0011 #include <linux/module.h>
0012 #include <linux/slab.h>
0013 #include <linux/videodev2.h>
0014 #include <media/v4l2-device.h>
0015 #include <media/v4l2-ctrls.h>
0016
0017 int v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev)
0018 {
0019     if (v4l2_dev == NULL)
0020         return -EINVAL;
0021
0022     INIT_LIST_HEAD(&v4l2_dev->subdevs);
0023     spin_lock_init(&v4l2_dev->lock);
0024     v4l2_prio_init(&v4l2_dev->prio);
0025     kref_init(&v4l2_dev->ref);
0026     get_device(dev);
0027     v4l2_dev->dev = dev;
0028     if (dev == NULL) {
0029         /* If dev == NULL, then name must be filled in by the caller */
0030         if (WARN_ON(!v4l2_dev->name[0]))
0031             return -EINVAL;
0032         return 0;
0033     }
0034
0035     /* Set name to driver name + device name if it is empty. */
0036     if (!v4l2_dev->name[0])
0037         snprintf(v4l2_dev->name, sizeof(v4l2_dev->name), "%s %s",
0038             dev->driver->name, dev_name(dev));
0039     if (!dev_get_drvdata(dev))
0040         dev_set_drvdata(dev, v4l2_dev);
0041     return 0;
0042 }
0043 EXPORT_SYMBOL_GPL(v4l2_device_register);
0044
0045 static void v4l2_device_release(struct kref *ref)
0046 {
0047     struct v4l2_device *v4l2_dev =
0048         container_of(ref, struct v4l2_device, ref);
0049
0050     if (v4l2_dev->release)
0051         v4l2_dev->release(v4l2_dev);
0052 }
0053
0054 int v4l2_device_put(struct v4l2_device *v4l2_dev)
0055 {
0056     return kref_put(&v4l2_dev->ref, v4l2_device_release);
0057 }
0058 EXPORT_SYMBOL_GPL(v4l2_device_put);
0059
0060 int v4l2_device_set_name(struct v4l2_device *v4l2_dev, const char *basename,
0061                         atomic_t *instance)
0062 {
0063     int num = atomic_inc_return(instance) - 1;
0064     int len = strlen(basename);
0065
0066     if (basename[len - 1] >= '0' && basename[len - 1] <= '9')
0067         snprintf(v4l2_dev->name, sizeof(v4l2_dev->name),
0068                 "%s-%d", basename, num);
0069     else
0070         snprintf(v4l2_dev->name, sizeof(v4l2_dev->name),
0071                 "%s%d", basename, num);
0072     return num;
0073 }
0074 EXPORT_SYMBOL_GPL(v4l2_device_set_name);
0075
0076 void v4l2_device_disconnect(struct v4l2_device *v4l2_dev)
0077 {
0078     if (v4l2_dev->dev == NULL)
0079         return;
0080
0081     if (dev_get_drvdata(v4l2_dev->dev) == v4l2_dev)
0082         dev_set_drvdata(v4l2_dev->dev, NULL);
0083     put_device(v4l2_dev->dev);
0084     v4l2_dev->dev = NULL;
0085 }
0086 EXPORT_SYMBOL_GPL(v4l2_device_disconnect);
0087
0088 void v4l2_device_unregister(struct v4l2_device *v4l2_dev)
0089 {
0090     struct v4l2_subdev *sd, *next;
0091
0092     /* Just return if v4l2_dev is NULL or if it was already
0093      * unregistered before. */
0094     if (v4l2_dev == NULL || !v4l2_dev->name[0])
0095         return;
0096     v4l2_device_disconnect(v4l2_dev);
0097
0098     /* Unregister subdevs */
0099     list_for_each_entry_safe(sd, next, &v4l2_dev->subdevs, list) {
0100         v4l2_device_unregister_subdev(sd);
0101         if (sd->flags & V4L2_SUBDEV_FL_IS_I2C)
0102             v4l2_i2c_subdev_unregister(sd);
0103         else if (sd->flags & V4L2_SUBDEV_FL_IS_SPI)
0104             v4l2_spi_subdev_unregister(sd);
0105     }
0106     /* Mark as unregistered, thus preventing duplicate unregistrations */
0107     v4l2_dev->name[0] = '\0';
0108 }
0109 EXPORT_SYMBOL_GPL(v4l2_device_unregister);
0110
0111 int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
0112                 struct v4l2_subdev *sd)
0113 {
0114     int err;
0115
0116     /* Check for valid input */
0117     if (!v4l2_dev || !sd || sd->v4l2_dev || !sd->name[0])
0118         return -EINVAL;
0119
0120     /*
0121      * The reason to acquire the module here is to avoid unloading
0122      * a module of sub-device which is registered to a media
0123      * device. To make it possible to unload modules for media
0124      * devices that also register sub-devices, do not
0125      * try_module_get() such sub-device owners.
0126      */
0127     sd->owner_v4l2_dev = v4l2_dev->dev && v4l2_dev->dev->driver &&
0128         sd->owner == v4l2_dev->dev->driver->owner;
0129
0130     if (!sd->owner_v4l2_dev && !try_module_get(sd->owner))
0131         return -ENODEV;
0132
0133     sd->v4l2_dev = v4l2_dev;
0134     /* This just returns 0 if either of the two args is NULL */
0135     err = v4l2_ctrl_add_handler(v4l2_dev->ctrl_handler, sd->ctrl_handler,
0136                     NULL, true);
0137     if (err)
0138         goto error_module;
0139
0140 #if defined(CONFIG_MEDIA_CONTROLLER)
0141     /* Register the entity. */
0142     if (v4l2_dev->mdev) {
0143         err = media_device_register_entity(v4l2_dev->mdev, &sd->entity);
0144         if (err < 0)
0145             goto error_module;
0146     }
0147 #endif
0148
0149     if (sd->internal_ops && sd->internal_ops->registered) {
0150         err = sd->internal_ops->registered(sd);
0151         if (err)
0152             goto error_unregister;
0153     }
0154
0155     spin_lock(&v4l2_dev->lock);
0156     list_add_tail(&sd->list, &v4l2_dev->subdevs);
0157     spin_unlock(&v4l2_dev->lock);
0158
0159     return 0;
0160
0161 error_unregister:
0162 #if defined(CONFIG_MEDIA_CONTROLLER)
0163     media_device_unregister_entity(&sd->entity);
0164 #endif
0165 error_module:
0166     if (!sd->owner_v4l2_dev)
0167         module_put(sd->owner);
0168     sd->v4l2_dev = NULL;
0169     return err;
0170 }
0171 EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
0172
0173 static void v4l2_subdev_release(struct v4l2_subdev *sd)
0174 {
0175     struct module *owner = !sd->owner_v4l2_dev ? sd->owner : NULL;
0176
0177     if (sd->internal_ops && sd->internal_ops->release)
0178         sd->internal_ops->release(sd);
0179     sd->devnode = NULL;
0180     module_put(owner);
0181 }
0182
0183 static void v4l2_device_release_subdev_node(struct video_device *vdev)
0184 {
0185     v4l2_subdev_release(video_get_drvdata(vdev));
0186     kfree(vdev);
0187 }
0188
0189 int __v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev,
0190                     bool read_only)
0191 {
0192     struct video_device *vdev;
0193     struct v4l2_subdev *sd;
0194     int err;
0195
0196     /* Register a device node for every subdev marked with the
0197      * V4L2_SUBDEV_FL_HAS_DEVNODE flag.
0198      */
0199     list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
0200         if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
0201             continue;
0202
0203         if (sd->devnode)
0204             continue;
0205
0206         vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
0207         if (!vdev) {
0208             err = -ENOMEM;
0209             goto clean_up;
0210         }
0211
0212         video_set_drvdata(vdev, sd);
0213         strscpy(vdev->name, sd->name, sizeof(vdev->name));
0214         vdev->dev_parent = sd->dev;
0215         vdev->v4l2_dev = v4l2_dev;
0216         vdev->fops = &v4l2_subdev_fops;
0217         vdev->release = v4l2_device_release_subdev_node;
0218         vdev->ctrl_handler = sd->ctrl_handler;
0219         if (read_only)
0220             set_bit(V4L2_FL_SUBDEV_RO_DEVNODE, &vdev->flags);
0221         sd->devnode = vdev;
0222         err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
0223                           sd->owner);
0224         if (err < 0) {
0225             sd->devnode = NULL;
0226             kfree(vdev);
0227             goto clean_up;
0228         }
0229 #if defined(CONFIG_MEDIA_CONTROLLER)
0230         sd->entity.info.dev.major = VIDEO_MAJOR;
0231         sd->entity.info.dev.minor = vdev->minor;
0232
0233         /* Interface is created by __video_register_device() */
0234         if (vdev->v4l2_dev->mdev) {
0235             struct media_link *link;
0236
0237             link = media_create_intf_link(&sd->entity,
0238                               &vdev->intf_devnode->intf,
0239                               MEDIA_LNK_FL_ENABLED |
0240                               MEDIA_LNK_FL_IMMUTABLE);
0241             if (!link) {
0242                 err = -ENOMEM;
0243                 goto clean_up;
0244             }
0245         }
0246 #endif
0247     }
0248     return 0;
0249
0250 clean_up:
0251     list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
0252         if (!sd->devnode)
0253             break;
0254         video_unregister_device(sd->devnode);
0255     }
0256
0257     return err;
0258 }
0259 EXPORT_SYMBOL_GPL(__v4l2_device_register_subdev_nodes);
0260
0261 void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
0262 {
0263     struct v4l2_device *v4l2_dev;
0264
0265     /* return if it isn't registered */
0266     if (sd == NULL || sd->v4l2_dev == NULL)
0267         return;
0268
0269     v4l2_dev = sd->v4l2_dev;
0270
0271     spin_lock(&v4l2_dev->lock);
0272     list_del(&sd->list);
0273     spin_unlock(&v4l2_dev->lock);
0274
0275     if (sd->internal_ops && sd->internal_ops->unregistered)
0276         sd->internal_ops->unregistered(sd);
0277     sd->v4l2_dev = NULL;
0278
0279 #if defined(CONFIG_MEDIA_CONTROLLER)
0280     if (v4l2_dev->mdev) {
0281         /*
0282          * No need to explicitly remove links, as both pads and
0283          * links are removed by the function below, in the right order
0284          */
0285         media_device_unregister_entity(&sd->entity);
0286     }
0287 #endif
0288     if (sd->devnode)
0289         video_unregister_device(sd->devnode);
0290     else
0291         v4l2_subdev_release(sd);
0292 }
0293 EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);