/*
* Media device node
*
* Copyright (C) 2010 Nokia Corporation
*
* Based on drivers/media/video/v4l2_dev.c code authored by
* Mauro Carvalho Chehab <mchehab@infradead.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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* --
*
* 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 unsigned int 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 POLLERR | POLLHUP;
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 [31mCONFIG_COMPAT[0m
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 [31mCONFIG_COMPAT[0m
.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 and register the character device */
cdev_init(&devnode->cdev, &media_devnode_fops);
devnode->cdev.owner = owner;
devnode->cdev.kobj.parent = &devnode->dev.kobj;
ret = cdev_add(&devnode->cdev, MKDEV(MAJOR(media_dev_t), devnode->minor), 1);
if (ret < 0) {
pr_err("%s: cdev_add failed\n", __func__);
goto cdev_add_error;
}
/* Part 3: Add the media device */
ret = device_add(&devnode->dev);
if (ret < 0) {
pr_err("%s: device_add failed\n", __func__);
goto device_add_error;
}
/* Part 4: Activate this minor. The char device can now be used. */
set_bit(MEDIA_FLAG_REGISTERED, &devnode->flags);
return 0;
device_add_error:
cdev_del(&devnode->cdev);
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_del(&devnode->cdev);
mutex_unlock(&media_devnode_lock);
device_del(&devnode->dev);
devnode->media_dev = NULL;
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");