| /* |
| * 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> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * -- |
| * |
| * 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); |
| |
| /* 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); |
| |
| mutex_lock(&media_devnode_lock); |
| /* Mark device node number as free */ |
| clear_bit(devnode->minor, media_devnode_nums); |
| mutex_unlock(&media_devnode_lock); |
| |
| /* 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 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); |
| |
| pr_debug("%s: Media Release\n", __func__); |
| 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, |
| .llseek = no_llseek, |
| }; |
| |
| 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_next_zero_bit(media_devnode_nums, MEDIA_NUM_DEVICES, 0); |
| 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); |
| 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 */ |
| ret = cdev_device_add(&devnode->cdev, &devnode->dev); |
| if (ret < 0) { |
| pr_err("%s: cdev_device_add failed\n", __func__); |
| goto cdev_add_error; |
| } |
| |
| /* Part 4: Activate this minor. The char device can now be used. */ |
| set_bit(MEDIA_FLAG_REGISTERED, &devnode->flags); |
| |
| 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; |
| 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) |
| { |
| 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"); |