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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327// SPDX-License-Identifier: GPL-2.0-only/* * Media device node * * Copyright (C) 2010 Nokia Corporation * * Based on drivers/media/video/v4l2_dev.c code authored by * Mauro Carvalho Chehab <mchehab@kernel.org> (version 2) * Alan Cox, <alan@lxorguk.ukuu.org.uk> (version 1) * * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com> * Sakari Ailus <sakari.ailus@iki.fi> * * -- * * Generic media device node infrastructure to register and unregister * character devices using a dynamic major number and proper reference * counting. */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/errno.h>#include <linux/init.h>#include <linux/module.h>#include <linux/kernel.h>#include <linux/kmod.h>#include <linux/slab.h>#include <linux/mm.h>#include <linux/string.h>#include <linux/types.h>#include <linux/uaccess.h>
#include <media/media-devnode.h>#include <media/media-device.h>
#define MEDIA_NUM_DEVICES 256#define MEDIA_NAME "media"
static dev_t media_dev_t;
/* * Active devices */static DEFINE_MUTEX(media_devnode_lock);static DECLARE_BITMAP(media_devnode_nums, MEDIA_NUM_DEVICES);
/* debugfs */struct dentry *media_debugfs_root;
/* Called when the last user of the media device exits. */static void media_devnode_release(struct device *cd){ struct media_devnode *devnode = to_media_devnode(cd);
/* Release media_devnode and perform other cleanups as needed. */ if (devnode->release) devnode->release(devnode);
kfree(devnode); pr_debug("%s: Media Devnode Deallocated\n", __func__);}
static const struct bus_type media_bus_type = { .name = MEDIA_NAME,};
static ssize_t media_read(struct file *filp, char __user *buf, size_t sz, loff_t *off){ struct media_devnode *devnode = media_devnode_data(filp);
if (!devnode->fops->read) return -EINVAL; if (!media_devnode_is_registered(devnode)) return -EIO; return devnode->fops->read(filp, buf, sz, off);}
static ssize_t media_write(struct file *filp, const char __user *buf, size_t sz, loff_t *off){ struct media_devnode *devnode = media_devnode_data(filp);
if (!devnode->fops->write) return -EINVAL; if (!media_devnode_is_registered(devnode)) return -EIO; return devnode->fops->write(filp, buf, sz, off);}
static __poll_t media_poll(struct file *filp, struct poll_table_struct *poll){ struct media_devnode *devnode = media_devnode_data(filp);
if (!media_devnode_is_registered(devnode)) return EPOLLERR | EPOLLHUP; if (!devnode->fops->poll) return DEFAULT_POLLMASK; return devnode->fops->poll(filp, poll);}
static long__media_ioctl(struct file *filp, unsigned int cmd, unsigned long arg, long (*ioctl_func)(struct file *filp, unsigned int cmd, unsigned long arg)){ struct media_devnode *devnode = media_devnode_data(filp);
if (!ioctl_func) return -ENOTTY;
if (!media_devnode_is_registered(devnode)) return -EIO;
return ioctl_func(filp, cmd, arg);}
static long media_ioctl(struct file *filp, unsigned int cmd, unsigned long arg){ struct media_devnode *devnode = media_devnode_data(filp);
return __media_ioctl(filp, cmd, arg, devnode->fops->ioctl);}
#ifdef CONFIG_COMPAT
static long media_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg){ struct media_devnode *devnode = media_devnode_data(filp);
return __media_ioctl(filp, cmd, arg, devnode->fops->compat_ioctl);}
#endif /* CONFIG_COMPAT */
/* Override for the open function */static int media_open(struct inode *inode, struct file *filp){ struct media_devnode *devnode; int ret;
/* Check if the media device is available. This needs to be done with * the media_devnode_lock held to prevent an open/unregister race: * without the lock, the device could be unregistered and freed between * the media_devnode_is_registered() and get_device() calls, leading to * a crash. */ mutex_lock(&media_devnode_lock); devnode = container_of(inode->i_cdev, struct media_devnode, cdev); /* return ENXIO if the media device has been removed already or if it is not registered anymore. */ if (!media_devnode_is_registered(devnode)) { mutex_unlock(&media_devnode_lock); return -ENXIO; } /* and increase the device refcount */ get_device(&devnode->dev); mutex_unlock(&media_devnode_lock);
filp->private_data = devnode;
if (devnode->fops->open) { ret = devnode->fops->open(filp); if (ret) { put_device(&devnode->dev); filp->private_data = NULL; return ret; } }
return 0;}
/* Override for the release function */static int media_release(struct inode *inode, struct file *filp){ struct media_devnode *devnode = media_devnode_data(filp);
if (devnode->fops->release) devnode->fops->release(filp);
filp->private_data = NULL;
/* decrease the refcount unconditionally since the release() return value is ignored. */ put_device(&devnode->dev);
return 0;}
static const struct file_operations media_devnode_fops = { .owner = THIS_MODULE, .read = media_read, .write = media_write, .open = media_open, .unlocked_ioctl = media_ioctl,#ifdef CONFIG_COMPAT .compat_ioctl = media_compat_ioctl,#endif /* CONFIG_COMPAT */ .release = media_release, .poll = media_poll,};
int __must_check media_devnode_register(struct media_device *mdev, struct media_devnode *devnode, struct module *owner){ int minor; int ret;
/* Part 1: Find a free minor number */ mutex_lock(&media_devnode_lock); minor = find_first_zero_bit(media_devnode_nums, MEDIA_NUM_DEVICES); if (minor == MEDIA_NUM_DEVICES) { mutex_unlock(&media_devnode_lock); pr_err("could not get a free minor\n"); kfree(devnode); return -ENFILE; }
set_bit(minor, media_devnode_nums); mutex_unlock(&media_devnode_lock);
devnode->minor = minor; devnode->media_dev = mdev;
/* Part 1: Initialize dev now to use dev.kobj for cdev.kobj.parent */ devnode->dev.bus = &media_bus_type; devnode->dev.devt = MKDEV(MAJOR(media_dev_t), devnode->minor); devnode->dev.release = media_devnode_release; if (devnode->parent) devnode->dev.parent = devnode->parent; dev_set_name(&devnode->dev, "media%d", devnode->minor); dev_set_drvdata(&devnode->dev, mdev); device_initialize(&devnode->dev);
/* Part 2: Initialize the character device */ cdev_init(&devnode->cdev, &media_devnode_fops); devnode->cdev.owner = owner; kobject_set_name(&devnode->cdev.kobj, "media%d", devnode->minor);
/* Part 3: Add the media and char device */ set_bit(MEDIA_FLAG_REGISTERED, &devnode->flags); ret = cdev_device_add(&devnode->cdev, &devnode->dev); if (ret < 0) { clear_bit(MEDIA_FLAG_REGISTERED, &devnode->flags); pr_err("%s: cdev_device_add failed\n", __func__); goto cdev_add_error; }
return 0;
cdev_add_error: mutex_lock(&media_devnode_lock); clear_bit(devnode->minor, media_devnode_nums); devnode->media_dev = NULL; mutex_unlock(&media_devnode_lock);
put_device(&devnode->dev); return ret;}
void media_devnode_unregister_prepare(struct media_devnode *devnode){ /* Check if devnode was ever registered at all */ if (!media_devnode_is_registered(devnode)) return;
mutex_lock(&media_devnode_lock); clear_bit(MEDIA_FLAG_REGISTERED, &devnode->flags); mutex_unlock(&media_devnode_lock);}
void media_devnode_unregister(struct media_devnode *devnode){ mutex_lock(&media_devnode_lock); /* Delete the cdev on this minor as well */ cdev_device_del(&devnode->cdev, &devnode->dev); devnode->media_dev = NULL; clear_bit(devnode->minor, media_devnode_nums); mutex_unlock(&media_devnode_lock);
put_device(&devnode->dev);}
/* * Initialise media for linux */static int __init media_devnode_init(void){ int ret;
pr_info("Linux media interface: v0.10\n"); ret = alloc_chrdev_region(&media_dev_t, 0, MEDIA_NUM_DEVICES, MEDIA_NAME); if (ret < 0) { pr_warn("unable to allocate major\n"); return ret; }
ret = bus_register(&media_bus_type); if (ret < 0) { unregister_chrdev_region(media_dev_t, MEDIA_NUM_DEVICES); pr_warn("bus_register failed\n"); return -EIO; }
return 0;}
static void __exit media_devnode_exit(void){ debugfs_remove_recursive(media_debugfs_root); bus_unregister(&media_bus_type); unregister_chrdev_region(media_dev_t, MEDIA_NUM_DEVICES);}
subsys_initcall(media_devnode_init);module_exit(media_devnode_exit)
MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");MODULE_DESCRIPTION("Device node registration for media drivers");MODULE_LICENSE("GPL");