[thirdparty/kernel/stable.git] / drivers / gpu / drm / drm_dp_aux_dev.c

/*
 * Copyright © 2015 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 * Authors:
 *    Rafael Antognolli <rafael.antognolli@intel.com>
 *
 */

#include <linux/device.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched/signal.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/uio.h>

#include <drm/drm_crtc.h>
#include <drm/drm_dp_helper.h>
#include <drm/drm_print.h>

#include "drm_crtc_helper_internal.h"

struct drm_dp_aux_dev {
	unsigned index;
	struct drm_dp_aux *aux;
	struct device *dev;
	struct kref refcount;
	atomic_t usecount;
};

#define DRM_AUX_MINORS	256
#define AUX_MAX_OFFSET	(1 << 20)
static DEFINE_IDR(aux_idr);
static DEFINE_MUTEX(aux_idr_mutex);
static struct class *drm_dp_aux_dev_class;
static int drm_dev_major = -1;

static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_minor(unsigned index)
{
	struct drm_dp_aux_dev *aux_dev = NULL;

	mutex_lock(&aux_idr_mutex);
	aux_dev = idr_find(&aux_idr, index);
	if (!kref_get_unless_zero(&aux_dev->refcount))
		aux_dev = NULL;
	mutex_unlock(&aux_idr_mutex);

	return aux_dev;
}

static struct drm_dp_aux_dev *alloc_drm_dp_aux_dev(struct drm_dp_aux *aux)
{
	struct drm_dp_aux_dev *aux_dev;
	int index;

	aux_dev = kzalloc(sizeof(*aux_dev), GFP_KERNEL);
	if (!aux_dev)
		return ERR_PTR(-ENOMEM);
	aux_dev->aux = aux;
	atomic_set(&aux_dev->usecount, 1);
	kref_init(&aux_dev->refcount);

	mutex_lock(&aux_idr_mutex);
	index = idr_alloc_cyclic(&aux_idr, aux_dev, 0, DRM_AUX_MINORS,
				 GFP_KERNEL);
	mutex_unlock(&aux_idr_mutex);
	if (index < 0) {
		kfree(aux_dev);
		return ERR_PTR(index);
	}
	aux_dev->index = index;

	return aux_dev;
}

static void release_drm_dp_aux_dev(struct kref *ref)
{
	struct drm_dp_aux_dev *aux_dev =
		container_of(ref, struct drm_dp_aux_dev, refcount);

	kfree(aux_dev);
}

static ssize_t name_show(struct device *dev,
			 struct device_attribute *attr, char *buf)
{
	ssize_t res;
	struct drm_dp_aux_dev *aux_dev =
		drm_dp_aux_dev_get_by_minor(MINOR(dev->devt));

	if (!aux_dev)
		return -ENODEV;

	res = sprintf(buf, "%s\n", aux_dev->aux->name);
	kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);

	return res;
}
static DEVICE_ATTR_RO(name);

static struct attribute *drm_dp_aux_attrs[] = {
	&dev_attr_name.attr,
	NULL,
};
ATTRIBUTE_GROUPS(drm_dp_aux);

static int auxdev_open(struct inode *inode, struct file *file)
{
	unsigned int minor = iminor(inode);
	struct drm_dp_aux_dev *aux_dev;

	aux_dev = drm_dp_aux_dev_get_by_minor(minor);
	if (!aux_dev)
		return -ENODEV;

	file->private_data = aux_dev;
	return 0;
}

static loff_t auxdev_llseek(struct file *file, loff_t offset, int whence)
{
	return fixed_size_llseek(file, offset, whence, AUX_MAX_OFFSET);
}

static ssize_t auxdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
	struct drm_dp_aux_dev *aux_dev = iocb->ki_filp->private_data;
	loff_t pos = iocb->ki_pos;
	ssize_t res = 0;

	if (!atomic_inc_not_zero(&aux_dev->usecount))
		return -ENODEV;

	iov_iter_truncate(to, AUX_MAX_OFFSET - pos);

	while (iov_iter_count(to)) {
		uint8_t buf[DP_AUX_MAX_PAYLOAD_BYTES];
		ssize_t todo = min(iov_iter_count(to), sizeof(buf));

		if (signal_pending(current)) {
			res = -ERESTARTSYS;
			break;
		}

		res = drm_dp_dpcd_read(aux_dev->aux, pos, buf, todo);
		if (res <= 0)
			break;

		if (copy_to_iter(buf, res, to) != res) {
			res = -EFAULT;
			break;
		}

		pos += res;
	}

	if (pos != iocb->ki_pos)
		res = pos - iocb->ki_pos;
	iocb->ki_pos = pos;

	if (atomic_dec_and_test(&aux_dev->usecount))
		wake_up_var(&aux_dev->usecount);

	return res;
}

static ssize_t auxdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
	struct drm_dp_aux_dev *aux_dev = iocb->ki_filp->private_data;
	loff_t pos = iocb->ki_pos;
	ssize_t res = 0;

	if (!atomic_inc_not_zero(&aux_dev->usecount))
		return -ENODEV;

	iov_iter_truncate(from, AUX_MAX_OFFSET - pos);

	while (iov_iter_count(from)) {
		uint8_t buf[DP_AUX_MAX_PAYLOAD_BYTES];
		ssize_t todo = min(iov_iter_count(from), sizeof(buf));

		if (signal_pending(current)) {
			res = -ERESTARTSYS;
			break;
		}

		if (!copy_from_iter_full(buf, todo, from)) {
			res = -EFAULT;
			break;
		}

		res = drm_dp_dpcd_write(aux_dev->aux, pos, buf, todo);
		if (res <= 0)
			break;

		pos += res;
	}

	if (pos != iocb->ki_pos)
		res = pos - iocb->ki_pos;
	iocb->ki_pos = pos;

	if (atomic_dec_and_test(&aux_dev->usecount))
		wake_up_var(&aux_dev->usecount);

	return res;
}

static int auxdev_release(struct inode *inode, struct file *file)
{
	struct drm_dp_aux_dev *aux_dev = file->private_data;

	kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
	return 0;
}

static const struct file_operations auxdev_fops = {
	.owner		= THIS_MODULE,
	.llseek		= auxdev_llseek,
	.read_iter	= auxdev_read_iter,
	.write_iter	= auxdev_write_iter,
	.open		= auxdev_open,
	.release	= auxdev_release,
};

#define to_auxdev(d) container_of(d, struct drm_dp_aux_dev, aux)

static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_aux(struct drm_dp_aux *aux)
{
	struct drm_dp_aux_dev *iter, *aux_dev = NULL;
	int id;

	/* don't increase kref count here because this function should only be
	 * used by drm_dp_aux_unregister_devnode. Thus, it will always have at
	 * least one reference - the one that drm_dp_aux_register_devnode
	 * created
	 */
	mutex_lock(&aux_idr_mutex);
	idr_for_each_entry(&aux_idr, iter, id) {
		if (iter->aux == aux) {
			aux_dev = iter;
			break;
		}
	}
	mutex_unlock(&aux_idr_mutex);
	return aux_dev;
}

void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux)
{
	struct drm_dp_aux_dev *aux_dev;
	unsigned int minor;

	aux_dev = drm_dp_aux_dev_get_by_aux(aux);
	if (!aux_dev) /* attach must have failed */
		return;

	mutex_lock(&aux_idr_mutex);
	idr_remove(&aux_idr, aux_dev->index);
	mutex_unlock(&aux_idr_mutex);

	atomic_dec(&aux_dev->usecount);
	wait_var_event(&aux_dev->usecount, !atomic_read(&aux_dev->usecount));

	minor = aux_dev->index;
	if (aux_dev->dev)
		device_destroy(drm_dp_aux_dev_class,
			       MKDEV(drm_dev_major, minor));

	DRM_DEBUG("drm_dp_aux_dev: aux [%s] unregistering\n", aux->name);
	kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
}

int drm_dp_aux_register_devnode(struct drm_dp_aux *aux)
{
	struct drm_dp_aux_dev *aux_dev;
	int res;

	aux_dev = alloc_drm_dp_aux_dev(aux);
	if (IS_ERR(aux_dev))
		return PTR_ERR(aux_dev);

	aux_dev->dev = device_create(drm_dp_aux_dev_class, aux->dev,
				     MKDEV(drm_dev_major, aux_dev->index), NULL,
				     "drm_dp_aux%d", aux_dev->index);
	if (IS_ERR(aux_dev->dev)) {
		res = PTR_ERR(aux_dev->dev);
		aux_dev->dev = NULL;
		goto error;
	}

	DRM_DEBUG("drm_dp_aux_dev: aux [%s] registered as minor %d\n",
		  aux->name, aux_dev->index);
	return 0;
error:
	drm_dp_aux_unregister_devnode(aux);
	return res;
}

int drm_dp_aux_dev_init(void)
{
	int res;

	drm_dp_aux_dev_class = class_create(THIS_MODULE, "drm_dp_aux_dev");
	if (IS_ERR(drm_dp_aux_dev_class)) {
		return PTR_ERR(drm_dp_aux_dev_class);
	}
	drm_dp_aux_dev_class->dev_groups = drm_dp_aux_groups;

	res = register_chrdev(0, "aux", &auxdev_fops);
	if (res < 0)
		goto out;
	drm_dev_major = res;

	return 0;
out:
	class_destroy(drm_dp_aux_dev_class);
	return res;
}

void drm_dp_aux_dev_exit(void)
{
	unregister_chrdev(drm_dev_major, "aux");
	class_destroy(drm_dp_aux_dev_class);
}
Commit	Line	Data
e94cb37b RA	1	/*
	2	* Copyright © 2015 Intel Corporation
	3	*
	4	* Permission is hereby granted, free of charge, to any person obtaining a
	5	* copy of this software and associated documentation files (the "Software"),
	6	* to deal in the Software without restriction, including without limitation
	7	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	8	* and/or sell copies of the Software, and to permit persons to whom the
	9	* Software is furnished to do so, subject to the following conditions:
	10	*
	11	* The above copyright notice and this permission notice (including the next
	12	* paragraph) shall be included in all copies or substantial portions of the
	13	* Software.
	14	*
	15	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	16	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	17	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	18	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	19	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
	20	* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
	21	* IN THE SOFTWARE.
	22	*
	23	* Authors:
	24	* Rafael Antognolli <rafael.antognolli@intel.com>
	25	*
	26	*/
	27
	28	#include <linux/device.h>
	29	#include <linux/fs.h>
e94cb37b RA	30	#include <linux/init.h>
	31	#include <linux/kernel.h>
	32	#include <linux/module.h>
580fc13f JN	33	#include <linux/sched/signal.h>
580fc13f JN	34	#include <linux/slab.h>
e94cb37b	35	#include <linux/uaccess.h>
3941dae1	36	#include <linux/uio.h>
580fc13f	37
e94cb37b	38	#include <drm/drm_crtc.h>
580fc13f JN	39	#include <drm/drm_dp_helper.h>
580fc13f JN	40	#include <drm/drm_print.h>
e94cb37b	41
e15c8f4b SV	42	#include "drm_crtc_helper_internal.h"
e15c8f4b SV	43
e94cb37b RA	44	struct drm_dp_aux_dev {
	45	unsigned index;
	46	struct drm_dp_aux *aux;
	47	struct device *dev;
	48	struct kref refcount;
	49	atomic_t usecount;
	50	};
	51
	52	#define DRM_AUX_MINORS 256
	53	#define AUX_MAX_OFFSET (1 << 20)
	54	static DEFINE_IDR(aux_idr);
	55	static DEFINE_MUTEX(aux_idr_mutex);
	56	static struct class *drm_dp_aux_dev_class;
	57	static int drm_dev_major = -1;
	58
	59	static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_minor(unsigned index)
	60	{
	61	struct drm_dp_aux_dev *aux_dev = NULL;
	62
	63	mutex_lock(&aux_idr_mutex);
	64	aux_dev = idr_find(&aux_idr, index);
	65	if (!kref_get_unless_zero(&aux_dev->refcount))
	66	aux_dev = NULL;
	67	mutex_unlock(&aux_idr_mutex);
	68
	69	return aux_dev;
	70	}
	71
	72	static struct drm_dp_aux_dev alloc_drm_dp_aux_dev(struct drm_dp_aux aux)
	73	{
	74	struct drm_dp_aux_dev *aux_dev;
	75	int index;
	76
	77	aux_dev = kzalloc(sizeof(*aux_dev), GFP_KERNEL);
	78	if (!aux_dev)
	79	return ERR_PTR(-ENOMEM);
	80	aux_dev->aux = aux;
	81	atomic_set(&aux_dev->usecount, 1);
	82	kref_init(&aux_dev->refcount);
	83
	84	mutex_lock(&aux_idr_mutex);
	85	index = idr_alloc_cyclic(&aux_idr, aux_dev, 0, DRM_AUX_MINORS,
	86	GFP_KERNEL);
	87	mutex_unlock(&aux_idr_mutex);
	88	if (index < 0) {
	89	kfree(aux_dev);
	90	return ERR_PTR(index);
	91	}
	92	aux_dev->index = index;
	93
	94	return aux_dev;
	95	}
	96
	97	static void release_drm_dp_aux_dev(struct kref *ref)
	98	{
	99	struct drm_dp_aux_dev *aux_dev =
	100	container_of(ref, struct drm_dp_aux_dev, refcount);
	101
	102	kfree(aux_dev);
	103	}
	104
	105	static ssize_t name_show(struct device *dev,
	106	struct device_attribute attr, char buf)
	107	{
108	ssize_t res;
109	struct drm_dp_aux_dev *aux_dev =
110	drm_dp_aux_dev_get_by_minor(MINOR(dev->devt));
111
112	if (!aux_dev)
113	return -ENODEV;
114
115	res = sprintf(buf, "%s\n", aux_dev->aux->name);
116	kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
117
118	return res;
119	}
120	static DEVICE_ATTR_RO(name);
121
122	static struct attribute *drm_dp_aux_attrs[] = {
123	&dev_attr_name.attr,
124	NULL,
125	};
126	ATTRIBUTE_GROUPS(drm_dp_aux);
127
128	static int auxdev_open(struct inode inode, struct file file)
129	{
130	unsigned int minor = iminor(inode);
131	struct drm_dp_aux_dev *aux_dev;
132
133	aux_dev = drm_dp_aux_dev_get_by_minor(minor);
134	if (!aux_dev)
135	return -ENODEV;
136
137	file->private_data = aux_dev;
138	return 0;
139	}
140
141	static loff_t auxdev_llseek(struct file *file, loff_t offset, int whence)
142	{
143	return fixed_size_llseek(file, offset, whence, AUX_MAX_OFFSET);
144	}
145
3941dae1	146	static ssize_t auxdev_read_iter(struct kiocb iocb, struct iov_iter to)
e94cb37b	147	{
3941dae1 AV	148	struct drm_dp_aux_dev *aux_dev = iocb->ki_filp->private_data;
3941dae1 AV	149	loff_t pos = iocb->ki_pos;
e94cb37b RA	150	ssize_t res = 0;
	151
	152	if (!atomic_inc_not_zero(&aux_dev->usecount))
	153	return -ENODEV;
	154
3941dae1	155	iov_iter_truncate(to, AUX_MAX_OFFSET - pos);
e94cb37b	156
3941dae1 AV	157	while (iov_iter_count(to)) {
	158	uint8_t buf[DP_AUX_MAX_PAYLOAD_BYTES];
	159	ssize_t todo = min(iov_iter_count(to), sizeof(buf));
e94cb37b	160
36230cb5	161	if (signal_pending(current)) {
3941dae1 AV	162	res = -ERESTARTSYS;
3941dae1 AV	163	break;
36230cb5 VS	164	}
36230cb5 VS	165
3941dae1 AV	166	res = drm_dp_dpcd_read(aux_dev->aux, pos, buf, todo);
	167	if (res <= 0)
	168	break;
	169
	170	if (copy_to_iter(buf, res, to) != res) {
	171	res = -EFAULT;
	172	break;
e94cb37b	173	}
3941dae1 AV	174
3941dae1 AV	175	pos += res;
e94cb37b RA	176	}
e94cb37b RA	177
3941dae1 AV	178	if (pos != iocb->ki_pos)
	179	res = pos - iocb->ki_pos;
	180	iocb->ki_pos = pos;
	181
d224985a PZ	182	if (atomic_dec_and_test(&aux_dev->usecount))
	183	wake_up_var(&aux_dev->usecount);
	184
e94cb37b RA	185	return res;
	186	}
	187
3941dae1	188	static ssize_t auxdev_write_iter(struct kiocb iocb, struct iov_iter from)
e94cb37b	189	{
3941dae1 AV	190	struct drm_dp_aux_dev *aux_dev = iocb->ki_filp->private_data;
3941dae1 AV	191	loff_t pos = iocb->ki_pos;
e94cb37b RA	192	ssize_t res = 0;
	193
	194	if (!atomic_inc_not_zero(&aux_dev->usecount))
	195	return -ENODEV;
	196
3941dae1	197	iov_iter_truncate(from, AUX_MAX_OFFSET - pos);
e94cb37b	198
3941dae1 AV	199	while (iov_iter_count(from)) {
	200	uint8_t buf[DP_AUX_MAX_PAYLOAD_BYTES];
	201	ssize_t todo = min(iov_iter_count(from), sizeof(buf));
e94cb37b	202
36230cb5	203	if (signal_pending(current)) {
3941dae1 AV	204	res = -ERESTARTSYS;
3941dae1 AV	205	break;
36230cb5 VS	206	}
36230cb5 VS	207
3941dae1 AV	208	if (!copy_from_iter_full(buf, todo, from)) {
	209	res = -EFAULT;
	210	break;
e94cb37b RA	211	}
e94cb37b RA	212
3941dae1 AV	213	res = drm_dp_dpcd_write(aux_dev->aux, pos, buf, todo);
	214	if (res <= 0)
	215	break;
	216
	217	pos += res;
e94cb37b RA	218	}
e94cb37b RA	219
3941dae1 AV	220	if (pos != iocb->ki_pos)
	221	res = pos - iocb->ki_pos;
	222	iocb->ki_pos = pos;
	223
d224985a PZ	224	if (atomic_dec_and_test(&aux_dev->usecount))
	225	wake_up_var(&aux_dev->usecount);
	226
e94cb37b RA	227	return res;
	228	}
	229
	230	static int auxdev_release(struct inode inode, struct file file)
	231	{
	232	struct drm_dp_aux_dev *aux_dev = file->private_data;
	233
	234	kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
	235	return 0;
	236	}
	237
	238	static const struct file_operations auxdev_fops = {
	239	.owner = THIS_MODULE,
	240	.llseek = auxdev_llseek,
3941dae1 AV	241	.read_iter = auxdev_read_iter,
3941dae1 AV	242	.write_iter = auxdev_write_iter,
e94cb37b RA	243	.open = auxdev_open,
	244	.release = auxdev_release,
	245	};
	246
	247	#define to_auxdev(d) container_of(d, struct drm_dp_aux_dev, aux)
	248
	249	static struct drm_dp_aux_dev drm_dp_aux_dev_get_by_aux(struct drm_dp_aux aux)
	250	{
	251	struct drm_dp_aux_dev iter, aux_dev = NULL;
	252	int id;
	253
	254	/* don't increase kref count here because this function should only be
	255	* used by drm_dp_aux_unregister_devnode. Thus, it will always have at
	256	* least one reference - the one that drm_dp_aux_register_devnode
	257	* created
	258	*/
	259	mutex_lock(&aux_idr_mutex);
	260	idr_for_each_entry(&aux_idr, iter, id) {
	261	if (iter->aux == aux) {
	262	aux_dev = iter;
	263	break;
	264	}
	265	}
	266	mutex_unlock(&aux_idr_mutex);
	267	return aux_dev;
	268	}
	269
e94cb37b RA	270	void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux)
	271	{
	272	struct drm_dp_aux_dev *aux_dev;
	273	unsigned int minor;
	274
	275	aux_dev = drm_dp_aux_dev_get_by_aux(aux);
	276	if (!aux_dev) /* attach must have failed */
	277	return;
	278
	279	mutex_lock(&aux_idr_mutex);
	280	idr_remove(&aux_idr, aux_dev->index);
	281	mutex_unlock(&aux_idr_mutex);
	282
	283	atomic_dec(&aux_dev->usecount);
d224985a	284	wait_var_event(&aux_dev->usecount, !atomic_read(&aux_dev->usecount));
e94cb37b RA	285
	286	minor = aux_dev->index;
	287	if (aux_dev->dev)
	288	device_destroy(drm_dp_aux_dev_class,
	289	MKDEV(drm_dev_major, minor));
	290
	291	DRM_DEBUG("drm_dp_aux_dev: aux [%s] unregistering\n", aux->name);
	292	kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
	293	}
e94cb37b	294
e94cb37b RA	295	int drm_dp_aux_register_devnode(struct drm_dp_aux *aux)
	296	{
	297	struct drm_dp_aux_dev *aux_dev;
	298	int res;
	299
	300	aux_dev = alloc_drm_dp_aux_dev(aux);
	301	if (IS_ERR(aux_dev))
	302	return PTR_ERR(aux_dev);
	303
	304	aux_dev->dev = device_create(drm_dp_aux_dev_class, aux->dev,
	305	MKDEV(drm_dev_major, aux_dev->index), NULL,
	306	"drm_dp_aux%d", aux_dev->index);
	307	if (IS_ERR(aux_dev->dev)) {
	308	res = PTR_ERR(aux_dev->dev);
	309	aux_dev->dev = NULL;
	310	goto error;
	311	}
	312
	313	DRM_DEBUG("drm_dp_aux_dev: aux [%s] registered as minor %d\n",
	314	aux->name, aux_dev->index);
	315	return 0;
	316	error:
	317	drm_dp_aux_unregister_devnode(aux);
	318	return res;
	319	}
e94cb37b RA	320
	321	int drm_dp_aux_dev_init(void)
	322	{
	323	int res;
	324
	325	drm_dp_aux_dev_class = class_create(THIS_MODULE, "drm_dp_aux_dev");
	326	if (IS_ERR(drm_dp_aux_dev_class)) {
da82ee99	327	return PTR_ERR(drm_dp_aux_dev_class);
e94cb37b RA	328	}
	329	drm_dp_aux_dev_class->dev_groups = drm_dp_aux_groups;
	330
	331	res = register_chrdev(0, "aux", &auxdev_fops);
	332	if (res < 0)
	333	goto out;
	334	drm_dev_major = res;
	335
	336	return 0;
	337	out:
	338	class_destroy(drm_dp_aux_dev_class);
	339	return res;
	340	}
e94cb37b RA	341
	342	void drm_dp_aux_dev_exit(void)
	343	{
	344	unregister_chrdev(drm_dev_major, "aux");
	345	class_destroy(drm_dp_aux_dev_class);
	346	}