[linux-2.6-block.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/slab.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/uio.h>
#include <drm/drm_dp_helper.h>
#include <drm/drm_crtc.h>
#include <drm/drmP.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>
	30	#include <linux/slab.h>
	31	#include <linux/init.h>
	32	#include <linux/kernel.h>
	33	#include <linux/module.h>
	34	#include <linux/uaccess.h>
3941dae1	35	#include <linux/uio.h>
e94cb37b RA	36	#include <drm/drm_dp_helper.h>
	37	#include <drm/drm_crtc.h>
	38	#include <drm/drmP.h>
	39
e15c8f4b DV	40	#include "drm_crtc_helper_internal.h"
e15c8f4b DV	41
e94cb37b RA	42	struct drm_dp_aux_dev {
	43	unsigned index;
	44	struct drm_dp_aux *aux;
	45	struct device *dev;
	46	struct kref refcount;
	47	atomic_t usecount;
	48	};
	49
	50	#define DRM_AUX_MINORS 256
	51	#define AUX_MAX_OFFSET (1 << 20)
	52	static DEFINE_IDR(aux_idr);
	53	static DEFINE_MUTEX(aux_idr_mutex);
	54	static struct class *drm_dp_aux_dev_class;
	55	static int drm_dev_major = -1;
	56
	57	static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_minor(unsigned index)
	58	{
	59	struct drm_dp_aux_dev *aux_dev = NULL;
	60
	61	mutex_lock(&aux_idr_mutex);
	62	aux_dev = idr_find(&aux_idr, index);
	63	if (!kref_get_unless_zero(&aux_dev->refcount))
	64	aux_dev = NULL;
	65	mutex_unlock(&aux_idr_mutex);
	66
	67	return aux_dev;
	68	}
	69
	70	static struct drm_dp_aux_dev alloc_drm_dp_aux_dev(struct drm_dp_aux aux)
	71	{
	72	struct drm_dp_aux_dev *aux_dev;
	73	int index;
	74
	75	aux_dev = kzalloc(sizeof(*aux_dev), GFP_KERNEL);
	76	if (!aux_dev)
	77	return ERR_PTR(-ENOMEM);
	78	aux_dev->aux = aux;
	79	atomic_set(&aux_dev->usecount, 1);
	80	kref_init(&aux_dev->refcount);
	81
	82	mutex_lock(&aux_idr_mutex);
	83	index = idr_alloc_cyclic(&aux_idr, aux_dev, 0, DRM_AUX_MINORS,
	84	GFP_KERNEL);
	85	mutex_unlock(&aux_idr_mutex);
	86	if (index < 0) {
	87	kfree(aux_dev);
	88	return ERR_PTR(index);
	89	}
	90	aux_dev->index = index;
	91
	92	return aux_dev;
	93	}
	94
	95	static void release_drm_dp_aux_dev(struct kref *ref)
	96	{
	97	struct drm_dp_aux_dev *aux_dev =
	98	container_of(ref, struct drm_dp_aux_dev, refcount);
	99
	100	kfree(aux_dev);
	101	}
	102
	103	static ssize_t name_show(struct device *dev,
	104	struct device_attribute attr, char buf)
	105	{
106	ssize_t res;
107	struct drm_dp_aux_dev *aux_dev =
108	drm_dp_aux_dev_get_by_minor(MINOR(dev->devt));
109
110	if (!aux_dev)
111	return -ENODEV;
112
113	res = sprintf(buf, "%s\n", aux_dev->aux->name);
114	kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
115
116	return res;
117	}
118	static DEVICE_ATTR_RO(name);
119
120	static struct attribute *drm_dp_aux_attrs[] = {
121	&dev_attr_name.attr,
122	NULL,
123	};
124	ATTRIBUTE_GROUPS(drm_dp_aux);
125
126	static int auxdev_open(struct inode inode, struct file file)
127	{
128	unsigned int minor = iminor(inode);
129	struct drm_dp_aux_dev *aux_dev;
130
131	aux_dev = drm_dp_aux_dev_get_by_minor(minor);
132	if (!aux_dev)
133	return -ENODEV;
134
135	file->private_data = aux_dev;
136	return 0;
137	}
138
139	static loff_t auxdev_llseek(struct file *file, loff_t offset, int whence)
140	{
141	return fixed_size_llseek(file, offset, whence, AUX_MAX_OFFSET);
142	}
143
3941dae1	144	static ssize_t auxdev_read_iter(struct kiocb iocb, struct iov_iter to)
e94cb37b	145	{
3941dae1 AV	146	struct drm_dp_aux_dev *aux_dev = iocb->ki_filp->private_data;
3941dae1 AV	147	loff_t pos = iocb->ki_pos;
e94cb37b RA	148	ssize_t res = 0;
	149
	150	if (!atomic_inc_not_zero(&aux_dev->usecount))
	151	return -ENODEV;
	152
3941dae1	153	iov_iter_truncate(to, AUX_MAX_OFFSET - pos);
e94cb37b	154
3941dae1 AV	155	while (iov_iter_count(to)) {
	156	uint8_t buf[DP_AUX_MAX_PAYLOAD_BYTES];
	157	ssize_t todo = min(iov_iter_count(to), sizeof(buf));
e94cb37b	158
36230cb5	159	if (signal_pending(current)) {
3941dae1 AV	160	res = -ERESTARTSYS;
3941dae1 AV	161	break;
36230cb5 VS	162	}
36230cb5 VS	163
3941dae1 AV	164	res = drm_dp_dpcd_read(aux_dev->aux, pos, buf, todo);
	165	if (res <= 0)
	166	break;
	167
	168	if (copy_to_iter(buf, res, to) != res) {
	169	res = -EFAULT;
	170	break;
e94cb37b	171	}
3941dae1 AV	172
3941dae1 AV	173	pos += res;
e94cb37b RA	174	}
e94cb37b RA	175
3941dae1 AV	176	if (pos != iocb->ki_pos)
	177	res = pos - iocb->ki_pos;
	178	iocb->ki_pos = pos;
	179
d224985a PZ	180	if (atomic_dec_and_test(&aux_dev->usecount))
	181	wake_up_var(&aux_dev->usecount);
	182
e94cb37b RA	183	return res;
	184	}
	185
3941dae1	186	static ssize_t auxdev_write_iter(struct kiocb iocb, struct iov_iter from)
e94cb37b	187	{
3941dae1 AV	188	struct drm_dp_aux_dev *aux_dev = iocb->ki_filp->private_data;
3941dae1 AV	189	loff_t pos = iocb->ki_pos;
e94cb37b RA	190	ssize_t res = 0;
	191
	192	if (!atomic_inc_not_zero(&aux_dev->usecount))
	193	return -ENODEV;
	194
3941dae1	195	iov_iter_truncate(from, AUX_MAX_OFFSET - pos);
e94cb37b	196
3941dae1 AV	197	while (iov_iter_count(from)) {
	198	uint8_t buf[DP_AUX_MAX_PAYLOAD_BYTES];
	199	ssize_t todo = min(iov_iter_count(from), sizeof(buf));
e94cb37b	200
36230cb5	201	if (signal_pending(current)) {
3941dae1 AV	202	res = -ERESTARTSYS;
3941dae1 AV	203	break;
36230cb5 VS	204	}
36230cb5 VS	205
3941dae1 AV	206	if (!copy_from_iter_full(buf, todo, from)) {
	207	res = -EFAULT;
	208	break;
e94cb37b RA	209	}
e94cb37b RA	210
3941dae1 AV	211	res = drm_dp_dpcd_write(aux_dev->aux, pos, buf, todo);
	212	if (res <= 0)
	213	break;
	214
	215	pos += res;
e94cb37b RA	216	}
e94cb37b RA	217
3941dae1 AV	218	if (pos != iocb->ki_pos)
	219	res = pos - iocb->ki_pos;
	220	iocb->ki_pos = pos;
	221
d224985a PZ	222	if (atomic_dec_and_test(&aux_dev->usecount))
	223	wake_up_var(&aux_dev->usecount);
	224
e94cb37b RA	225	return res;
	226	}
	227
	228	static int auxdev_release(struct inode inode, struct file file)
	229	{
	230	struct drm_dp_aux_dev *aux_dev = file->private_data;
	231
	232	kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
	233	return 0;
	234	}
	235
	236	static const struct file_operations auxdev_fops = {
	237	.owner = THIS_MODULE,
	238	.llseek = auxdev_llseek,
3941dae1 AV	239	.read_iter = auxdev_read_iter,
3941dae1 AV	240	.write_iter = auxdev_write_iter,
e94cb37b RA	241	.open = auxdev_open,
	242	.release = auxdev_release,
	243	};
	244
	245	#define to_auxdev(d) container_of(d, struct drm_dp_aux_dev, aux)
	246
	247	static struct drm_dp_aux_dev drm_dp_aux_dev_get_by_aux(struct drm_dp_aux aux)
	248	{
	249	struct drm_dp_aux_dev iter, aux_dev = NULL;
	250	int id;
	251
	252	/* don't increase kref count here because this function should only be
	253	* used by drm_dp_aux_unregister_devnode. Thus, it will always have at
	254	* least one reference - the one that drm_dp_aux_register_devnode
	255	* created
	256	*/
	257	mutex_lock(&aux_idr_mutex);
	258	idr_for_each_entry(&aux_idr, iter, id) {
	259	if (iter->aux == aux) {
	260	aux_dev = iter;
	261	break;
	262	}
	263	}
	264	mutex_unlock(&aux_idr_mutex);
	265	return aux_dev;
	266	}
	267
e94cb37b RA	268	void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux)
	269	{
	270	struct drm_dp_aux_dev *aux_dev;
	271	unsigned int minor;
	272
	273	aux_dev = drm_dp_aux_dev_get_by_aux(aux);
	274	if (!aux_dev) /* attach must have failed */
	275	return;
	276
	277	mutex_lock(&aux_idr_mutex);
	278	idr_remove(&aux_idr, aux_dev->index);
	279	mutex_unlock(&aux_idr_mutex);
	280
	281	atomic_dec(&aux_dev->usecount);
d224985a	282	wait_var_event(&aux_dev->usecount, !atomic_read(&aux_dev->usecount));
e94cb37b RA	283
	284	minor = aux_dev->index;
	285	if (aux_dev->dev)
	286	device_destroy(drm_dp_aux_dev_class,
	287	MKDEV(drm_dev_major, minor));
	288
	289	DRM_DEBUG("drm_dp_aux_dev: aux [%s] unregistering\n", aux->name);
	290	kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
	291	}
e94cb37b	292
e94cb37b RA	293	int drm_dp_aux_register_devnode(struct drm_dp_aux *aux)
	294	{
	295	struct drm_dp_aux_dev *aux_dev;
	296	int res;
	297
	298	aux_dev = alloc_drm_dp_aux_dev(aux);
	299	if (IS_ERR(aux_dev))
	300	return PTR_ERR(aux_dev);
	301
	302	aux_dev->dev = device_create(drm_dp_aux_dev_class, aux->dev,
	303	MKDEV(drm_dev_major, aux_dev->index), NULL,
	304	"drm_dp_aux%d", aux_dev->index);
	305	if (IS_ERR(aux_dev->dev)) {
	306	res = PTR_ERR(aux_dev->dev);
	307	aux_dev->dev = NULL;
	308	goto error;
	309	}
	310
	311	DRM_DEBUG("drm_dp_aux_dev: aux [%s] registered as minor %d\n",
	312	aux->name, aux_dev->index);
	313	return 0;
	314	error:
	315	drm_dp_aux_unregister_devnode(aux);
	316	return res;
	317	}
e94cb37b RA	318
	319	int drm_dp_aux_dev_init(void)
	320	{
	321	int res;
	322
	323	drm_dp_aux_dev_class = class_create(THIS_MODULE, "drm_dp_aux_dev");
	324	if (IS_ERR(drm_dp_aux_dev_class)) {
da82ee99	325	return PTR_ERR(drm_dp_aux_dev_class);
e94cb37b RA	326	}
	327	drm_dp_aux_dev_class->dev_groups = drm_dp_aux_groups;
	328
	329	res = register_chrdev(0, "aux", &auxdev_fops);
	330	if (res < 0)
	331	goto out;
	332	drm_dev_major = res;
	333
	334	return 0;
	335	out:
	336	class_destroy(drm_dp_aux_dev_class);
	337	return res;
	338	}
e94cb37b RA	339
	340	void drm_dp_aux_dev_exit(void)
	341	{
	342	unregister_chrdev(drm_dev_major, "aux");
	343	class_destroy(drm_dp_aux_dev_class);
	344	}