/* * Video capture interface for Linux version 2 * * A generic video device interface for the LINUX operating system * using a set of device structures/vectors for low level operations. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. * * Authors: Alan Cox, (version 1) * Mauro Carvalho Chehab (version 2) * * Fixes: 20000516 Claudio Matsuoka * - Added procfs support */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define VIDEO_NUM_DEVICES 256 #define VIDEO_NAME "video4linux" /* * sysfs stuff */ static ssize_t show_index(struct device *cd, struct device_attribute *attr, char *buf) { struct video_device *vdev = to_video_device(cd); return sprintf(buf, "%i\n", vdev->index); } static ssize_t show_name(struct device *cd, struct device_attribute *attr, char *buf) { struct video_device *vdev = to_video_device(cd); return sprintf(buf, "%.*s\n", (int)sizeof(vdev->name), vdev->name); } static struct device_attribute video_device_attrs[] = { __ATTR(name, S_IRUGO, show_name, NULL), __ATTR(index, S_IRUGO, show_index, NULL), __ATTR_NULL }; /* * Active devices */ static struct video_device *video_device[VIDEO_NUM_DEVICES]; static DEFINE_MUTEX(videodev_lock); static DECLARE_BITMAP(devnode_nums[VFL_TYPE_MAX], VIDEO_NUM_DEVICES); /* Device node utility functions */ /* Note: these utility functions all assume that vfl_type is in the range [0, VFL_TYPE_MAX-1]. */ #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES /* Return the bitmap corresponding to vfl_type. */ static inline unsigned long *devnode_bits(int vfl_type) { /* Any types not assigned to fixed minor ranges must be mapped to one single bitmap for the purposes of finding a free node number since all those unassigned types use the same minor range. */ int idx = (vfl_type > VFL_TYPE_RADIO) ? VFL_TYPE_MAX - 1 : vfl_type; return devnode_nums[idx]; } #else /* Return the bitmap corresponding to vfl_type. */ static inline unsigned long *devnode_bits(int vfl_type) { return devnode_nums[vfl_type]; } #endif /* Mark device node number vdev->num as used */ static inline void devnode_set(struct video_device *vdev) { set_bit(vdev->num, devnode_bits(vdev->vfl_type)); } /* Mark device node number vdev->num as unused */ static inline void devnode_clear(struct video_device *vdev) { clear_bit(vdev->num, devnode_bits(vdev->vfl_type)); } /* Try to find a free device node number in the range [from, to> */ static inline int devnode_find(struct video_device *vdev, int from, int to) { return find_next_zero_bit(devnode_bits(vdev->vfl_type), to, from); } struct video_device *video_device_alloc(void) { return kzalloc(sizeof(struct video_device), GFP_KERNEL); } EXPORT_SYMBOL(video_device_alloc); void video_device_release(struct video_device *vdev) { kfree(vdev); } EXPORT_SYMBOL(video_device_release); void video_device_release_empty(struct video_device *vdev) { /* Do nothing */ /* Only valid when the video_device struct is a static. */ } EXPORT_SYMBOL(video_device_release_empty); static inline void video_get(struct video_device *vdev) { get_device(&vdev->dev); } static inline void video_put(struct video_device *vdev) { put_device(&vdev->dev); } /* Called when the last user of the video device exits. */ static void v4l2_device_release(struct device *cd) { struct video_device *vdev = to_video_device(cd); struct v4l2_device *v4l2_dev = vdev->v4l2_dev; mutex_lock(&videodev_lock); if (WARN_ON(video_device[vdev->minor] != vdev)) { /* should not happen */ mutex_unlock(&videodev_lock); return; } /* Free up this device for reuse */ video_device[vdev->minor] = NULL; /* Delete the cdev on this minor as well */ cdev_del(vdev->cdev); /* Just in case some driver tries to access this from the release() callback. */ vdev->cdev = NULL; /* Mark device node number as free */ devnode_clear(vdev); mutex_unlock(&videodev_lock); #if defined(CONFIG_MEDIA_CONTROLLER) if (v4l2_dev && v4l2_dev->mdev && vdev->vfl_type != VFL_TYPE_SUBDEV) media_device_unregister_entity(&vdev->entity); #endif /* Do not call v4l2_device_put if there is no release callback set. * Drivers that have no v4l2_device release callback might free the * v4l2_dev instance in the video_device release callback below, so we * must perform this check here. * * TODO: In the long run all drivers that use v4l2_device should use the * v4l2_device release callback. This check will then be unnecessary. */ if (v4l2_dev && v4l2_dev->release == NULL) v4l2_dev = NULL; /* Release video_device and perform other cleanups as needed. */ vdev->release(vdev); /* Decrease v4l2_device refcount */ if (v4l2_dev) v4l2_device_put(v4l2_dev); } static struct class video_class = { .name = VIDEO_NAME, .dev_attrs = video_device_attrs, }; struct video_device *video_devdata(struct file *file) { return video_device[iminor(file->f_path.dentry->d_inode)]; } EXPORT_SYMBOL(video_devdata); /* Priority handling */ static inline bool prio_is_valid(enum v4l2_priority prio) { return prio == V4L2_PRIORITY_BACKGROUND || prio == V4L2_PRIORITY_INTERACTIVE || prio == V4L2_PRIORITY_RECORD; } void v4l2_prio_init(struct v4l2_prio_state *global) { memset(global, 0, sizeof(*global)); } EXPORT_SYMBOL(v4l2_prio_init); int v4l2_prio_change(struct v4l2_prio_state *global, enum v4l2_priority *local, enum v4l2_priority new) { if (!prio_is_valid(new)) return -EINVAL; if (*local == new) return 0; atomic_inc(&global->prios[new]); if (prio_is_valid(*local)) atomic_dec(&global->prios[*local]); *local = new; return 0; } EXPORT_SYMBOL(v4l2_prio_change); void v4l2_prio_open(struct v4l2_prio_state *global, enum v4l2_priority *local) { v4l2_prio_change(global, local, V4L2_PRIORITY_DEFAULT); } EXPORT_SYMBOL(v4l2_prio_open); void v4l2_prio_close(struct v4l2_prio_state *global, enum v4l2_priority local) { if (prio_is_valid(local)) atomic_dec(&global->prios[local]); } EXPORT_SYMBOL(v4l2_prio_close); enum v4l2_priority v4l2_prio_max(struct v4l2_prio_state *global) { if (atomic_read(&global->prios[V4L2_PRIORITY_RECORD]) > 0) return V4L2_PRIORITY_RECORD; if (atomic_read(&global->prios[V4L2_PRIORITY_INTERACTIVE]) > 0) return V4L2_PRIORITY_INTERACTIVE; if (atomic_read(&global->prios[V4L2_PRIORITY_BACKGROUND]) > 0) return V4L2_PRIORITY_BACKGROUND; return V4L2_PRIORITY_UNSET; } EXPORT_SYMBOL(v4l2_prio_max); int v4l2_prio_check(struct v4l2_prio_state *global, enum v4l2_priority local) { return (local < v4l2_prio_max(global)) ? -EBUSY : 0; } EXPORT_SYMBOL(v4l2_prio_check); static ssize_t v4l2_read(struct file *filp, char __user *buf, size_t sz, loff_t *off) { struct video_device *vdev = video_devdata(filp); int ret = -ENODEV; if (!vdev->fops->read) return -EINVAL; if (vdev->lock && mutex_lock_interruptible(vdev->lock)) return -ERESTARTSYS; if (video_is_registered(vdev)) ret = vdev->fops->read(filp, buf, sz, off); if (vdev->lock) mutex_unlock(vdev->lock); return ret; } static ssize_t v4l2_write(struct file *filp, const char __user *buf, size_t sz, loff_t *off) { struct video_device *vdev = video_devdata(filp); int ret = -ENODEV; if (!vdev->fops->write) return -EINVAL; if (vdev->lock && mutex_lock_interruptible(vdev->lock)) return -ERESTARTSYS; if (video_is_registered(vdev)) ret = vdev->fops->write(filp, buf, sz, off); if (vdev->lock) mutex_unlock(vdev->lock); return ret; } static unsigned int v4l2_poll(struct file *filp, struct poll_table_struct *poll) { struct video_device *vdev = video_devdata(filp); int ret = POLLERR | POLLHUP; if (!vdev->fops->poll) return DEFAULT_POLLMASK; if (vdev->lock) mutex_lock(vdev->lock); if (video_is_registered(vdev)) ret = vdev->fops->poll(filp, poll); if (vdev->lock) mutex_unlock(vdev->lock); return ret; } static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) { struct video_device *vdev = video_devdata(filp); int ret = -ENODEV; if (vdev->fops->unlocked_ioctl) { if (vdev->lock && mutex_lock_interruptible(vdev->lock)) return -ERESTARTSYS; if (video_is_registered(vdev)) ret = vdev->fops->unlocked_ioctl(filp, cmd, arg); if (vdev->lock) mutex_unlock(vdev->lock); } else if (vdev->fops->ioctl) { /* This code path is a replacement for the BKL. It is a major * hack but it will have to do for those drivers that are not * yet converted to use unlocked_ioctl. * * There are two options: if the driver implements struct * v4l2_device, then the lock defined there is used to * serialize the ioctls. Otherwise the v4l2 core lock defined * below is used. This lock is really bad since it serializes * completely independent devices. * * Both variants suffer from the same problem: if the driver * sleeps, then it blocks all ioctls since the lock is still * held. This is very common for VIDIOC_DQBUF since that * normally waits for a frame to arrive. As a result any other * ioctl calls will proceed very, very slowly since each call * will have to wait for the VIDIOC_QBUF to finish. Things that * should take 0.01s may now take 10-20 seconds. * * The workaround is to *not* take the lock for VIDIOC_DQBUF. * This actually works OK for videobuf-based drivers, since * videobuf will take its own internal lock. */ static DEFINE_MUTEX(v4l2_ioctl_mutex); struct mutex *m = vdev->v4l2_dev ? &vdev->v4l2_dev->ioctl_lock : &v4l2_ioctl_mutex; if (cmd != VIDIOC_DQBUF && mutex_lock_interruptible(m)) return -ERESTARTSYS; if (video_is_registered(vdev)) ret = vdev->fops->ioctl(filp, cmd, arg); if (cmd != VIDIOC_DQBUF) mutex_unlock(m); } else ret = -ENOTTY; return ret; } #ifdef CONFIG_MMU #define v4l2_get_unmapped_area NULL #else static unsigned long v4l2_get_unmapped_area(struct file *filp, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags) { struct video_device *vdev = video_devdata(filp); if (!vdev->fops->get_unmapped_area) return -ENOSYS; if (!video_is_registered(vdev)) return -ENODEV; return vdev->fops->get_unmapped_area(filp, addr, len, pgoff, flags); } #endif static int v4l2_mmap(struct file *filp, struct vm_area_struct *vm) { struct video_device *vdev = video_devdata(filp); int ret = -ENODEV; if (!vdev->fops->mmap) return ret; if (vdev->lock && mutex_lock_interruptible(vdev->lock)) return -ERESTARTSYS; if (video_is_registered(vdev)) ret = vdev->fops->mmap(filp, vm); if (vdev->lock) mutex_unlock(vdev->lock); return ret; } /* Override for the open function */ static int v4l2_open(struct inode *inode, struct file *filp) { struct video_device *vdev; int ret = 0; /* Check if the video device is available */ mutex_lock(&videodev_lock); vdev = video_devdata(filp); /* return ENODEV if the video device has already been removed. */ if (vdev == NULL || !video_is_registered(vdev)) { mutex_unlock(&videodev_lock); return -ENODEV; } /* and increase the device refcount */ video_get(vdev); mutex_unlock(&videodev_lock); if (vdev->fops->open) { if (vdev->lock && mutex_lock_interruptible(vdev->lock)) { ret = -ERESTARTSYS; goto err; } if (video_is_registered(vdev)) ret = vdev->fops->open(filp); else ret = -ENODEV; if (vdev->lock) mutex_unlock(vdev->lock); } err: /* decrease the refcount in case of an error */ if (ret) video_put(vdev); return ret; } /* Override for the release function */ static int v4l2_release(struct inode *inode, struct file *filp) { struct video_device *vdev = video_devdata(filp); int ret = 0; if (vdev->fops->release) { if (vdev->lock) mutex_lock(vdev->lock); vdev->fops->release(filp); if (vdev->lock) mutex_unlock(vdev->lock); } /* decrease the refcount unconditionally since the release() return value is ignored. */ video_put(vdev); return ret; } static const struct file_operations v4l2_fops = { .owner = THIS_MODULE, .read = v4l2_read, .write = v4l2_write, .open = v4l2_open, .get_unmapped_area = v4l2_get_unmapped_area, .mmap = v4l2_mmap, .unlocked_ioctl = v4l2_ioctl, #ifdef CONFIG_COMPAT .compat_ioctl = v4l2_compat_ioctl32, #endif .release = v4l2_release, .poll = v4l2_poll, .llseek = no_llseek, }; /** * get_index - assign stream index number based on parent device * @vdev: video_device to assign index number to, vdev->parent should be assigned * * Note that when this is called the new device has not yet been registered * in the video_device array, but it was able to obtain a minor number. * * This means that we can always obtain a free stream index number since * the worst case scenario is that there are VIDEO_NUM_DEVICES - 1 slots in * use of the video_device array. * * Returns a free index number. */ static int get_index(struct video_device *vdev) { /* This can be static since this function is called with the global videodev_lock held. */ static DECLARE_BITMAP(used, VIDEO_NUM_DEVICES); int i; /* Some drivers do not set the parent. In that case always return 0. */ if (vdev->parent == NULL) return 0; bitmap_zero(used, VIDEO_NUM_DEVICES); for (i = 0; i < VIDEO_NUM_DEVICES; i++) { if (video_device[i] != NULL && video_device[i]->parent == vdev->parent) { set_bit(video_device[i]->index, used); } } return find_first_zero_bit(used, VIDEO_NUM_DEVICES); } /** * __video_register_device - register video4linux devices * @vdev: video device structure we want to register * @type: type of device to register * @nr: which device node number (0 == /dev/video0, 1 == /dev/video1, ... * -1 == first free) * @warn_if_nr_in_use: warn if the desired device node number * was already in use and another number was chosen instead. * @owner: module that owns the video device node * * The registration code assigns minor numbers and device node numbers * based on the requested type and registers the new device node with * the kernel. * * This function assumes that struct video_device was zeroed when it * was allocated and does not contain any stale date. * * An error is returned if no free minor or device node number could be * found, or if the registration of the device node failed. * * Zero is returned on success. * * Valid types are * * %VFL_TYPE_GRABBER - A frame grabber * * %VFL_TYPE_VBI - Vertical blank data (undecoded) * * %VFL_TYPE_RADIO - A radio card * * %VFL_TYPE_SUBDEV - A subdevice */ int __video_register_device(struct video_device *vdev, int type, int nr, int warn_if_nr_in_use, struct module *owner) { int i = 0; int ret; int minor_offset = 0; int minor_cnt = VIDEO_NUM_DEVICES; const char *name_base; /* A minor value of -1 marks this video device as never having been registered */ vdev->minor = -1; /* the release callback MUST be present */ if (WARN_ON(!vdev->release)) return -EINVAL; /* v4l2_fh support */ spin_lock_init(&vdev->fh_lock); INIT_LIST_HEAD(&vdev->fh_list); /* Part 1: check device type */ switch (type) { case VFL_TYPE_GRABBER: name_base = "video"; break; case VFL_TYPE_VBI: name_base = "vbi"; break; case VFL_TYPE_RADIO: name_base = "radio"; break; case VFL_TYPE_SUBDEV: name_base = "v4l-subdev"; break; default: printk(KERN_ERR "%s called with unknown type: %d\n", __func__, type); return -EINVAL; } vdev->vfl_type = type; vdev->cdev = NULL; if (vdev->v4l2_dev) { if (vdev->v4l2_dev->dev) vdev->parent = vdev->v4l2_dev->dev; if (vdev->ctrl_handler == NULL) vdev->ctrl_handler = vdev->v4l2_dev->ctrl_handler; /* If the prio state pointer is NULL, then use the v4l2_device prio state. */ if (vdev->prio == NULL) vdev->prio = &vdev->v4l2_dev->prio; } /* Part 2: find a free minor, device node number and device index. */ #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES /* Keep the ranges for the first four types for historical * reasons. * Newer devices (not yet in place) should use the range * of 128-191 and just pick the first free minor there * (new style). */ switch (type) { case VFL_TYPE_GRABBER: minor_offset = 0; minor_cnt = 64; break; case VFL_TYPE_RADIO: minor_offset = 64; minor_cnt = 64; break; case VFL_TYPE_VBI: minor_offset = 224; minor_cnt = 32; break; default: minor_offset = 128; minor_cnt = 64; break; } #endif /* Pick a device node number */ mutex_lock(&videodev_lock); nr = devnode_find(vdev, nr == -1 ? 0 : nr, minor_cnt); if (nr == minor_cnt) nr = devnode_find(vdev, 0, minor_cnt); if (nr == minor_cnt) { printk(KERN_ERR "could not get a free device node number\n"); mutex_unlock(&videodev_lock); return -ENFILE; } #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES /* 1-on-1 mapping of device node number to minor number */ i = nr; #else /* The device node number and minor numbers are independent, so we just find the first free minor number. */ for (i = 0; i < VIDEO_NUM_DEVICES; i++) if (video_device[i] == NULL) break; if (i == VIDEO_NUM_DEVICES) { mutex_unlock(&videodev_lock); printk(KERN_ERR "could not get a free minor\n"); return -ENFILE; } #endif vdev->minor = i + minor_offset; vdev->num = nr; devnode_set(vdev); /* Should not happen since we thought this minor was free */ WARN_ON(video_device[vdev->minor] != NULL); vdev->index = get_index(vdev); mutex_unlock(&videodev_lock); /* Part 3: Initialize the character device */ vdev->cdev = cdev_alloc(); if (vdev->cdev == NULL) { ret = -ENOMEM; goto cleanup; } vdev->cdev->ops = &v4l2_fops; vdev->cdev->owner = owner; ret = cdev_add(vdev->cdev, MKDEV(VIDEO_MAJOR, vdev->minor), 1); if (ret < 0) { printk(KERN_ERR "%s: cdev_add failed\n", __func__); kfree(vdev->cdev); vdev->cdev = NULL; goto cleanup; } /* Part 4: register the device with sysfs */ vdev->dev.class = &video_class; vdev->dev.devt = MKDEV(VIDEO_MAJOR, vdev->minor); if (vdev->parent) vdev->dev.parent = vdev->parent; dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num); ret = device_register(&vdev->dev); if (ret < 0) { printk(KERN_ERR "%s: device_register failed\n", __func__); goto cleanup; } /* Register the release callback that will be called when the last reference to the device goes away. */ vdev->dev.release = v4l2_device_release; if (nr != -1 && nr != vdev->num && warn_if_nr_in_use) printk(KERN_WARNING "%s: requested %s%d, got %s\n", __func__, name_base, nr, video_device_node_name(vdev)); /* Increase v4l2_device refcount */ if (vdev->v4l2_dev) v4l2_device_get(vdev->v4l2_dev); #if defined(CONFIG_MEDIA_CONTROLLER) /* Part 5: Register the entity. */ if (vdev->v4l2_dev && vdev->v4l2_dev->mdev && vdev->vfl_type != VFL_TYPE_SUBDEV) { vdev->entity.type = MEDIA_ENT_T_DEVNODE_V4L; vdev->entity.name = vdev->name; vdev->entity.v4l.major = VIDEO_MAJOR; vdev->entity.v4l.minor = vdev->minor; ret = media_device_register_entity(vdev->v4l2_dev->mdev, &vdev->entity); if (ret < 0) printk(KERN_WARNING "%s: media_device_register_entity failed\n", __func__); } #endif /* Part 6: Activate this minor. The char device can now be used. */ set_bit(V4L2_FL_REGISTERED, &vdev->flags); mutex_lock(&videodev_lock); video_device[vdev->minor] = vdev; mutex_unlock(&videodev_lock); return 0; cleanup: mutex_lock(&videodev_lock); if (vdev->cdev) cdev_del(vdev->cdev); devnode_clear(vdev); mutex_unlock(&videodev_lock); /* Mark this video device as never having been registered. */ vdev->minor = -1; return ret; } EXPORT_SYMBOL(__video_register_device); /** * video_unregister_device - unregister a video4linux device * @vdev: the device to unregister * * This unregisters the passed device. Future open calls will * be met with errors. */ void video_unregister_device(struct video_device *vdev) { /* Check if vdev was ever registered at all */ if (!vdev || !video_is_registered(vdev)) return; mutex_lock(&videodev_lock); /* This must be in a critical section to prevent a race with v4l2_open. * Once this bit has been cleared video_get may never be called again. */ clear_bit(V4L2_FL_REGISTERED, &vdev->flags); mutex_unlock(&videodev_lock); device_unregister(&vdev->dev); } EXPORT_SYMBOL(video_unregister_device); /* * Initialise video for linux */ static int __init videodev_init(void) { dev_t dev = MKDEV(VIDEO_MAJOR, 0); int ret; printk(KERN_INFO "Linux video capture interface: v2.00\n"); ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME); if (ret < 0) { printk(KERN_WARNING "videodev: unable to get major %d\n", VIDEO_MAJOR); return ret; } ret = class_register(&video_class); if (ret < 0) { unregister_chrdev_region(dev, VIDEO_NUM_DEVICES); printk(KERN_WARNING "video_dev: class_register failed\n"); return -EIO; } return 0; } static void __exit videodev_exit(void) { dev_t dev = MKDEV(VIDEO_MAJOR, 0); class_unregister(&video_class); unregister_chrdev_region(dev, VIDEO_NUM_DEVICES); } module_init(videodev_init) module_exit(videodev_exit) MODULE_AUTHOR("Alan Cox, Mauro Carvalho Chehab "); MODULE_DESCRIPTION("Device registrar for Video4Linux drivers v2"); MODULE_LICENSE("GPL"); MODULE_ALIAS_CHARDEV_MAJOR(VIDEO_MAJOR); /* * Local variables: * c-basic-offset: 8 * End: */