2 * Copyright © 2015 Intel Corporation
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:
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
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
24 * Rafael Antognolli <rafael.antognolli@intel.com>
28 #include <linux/device.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>
35 #include <linux/uio.h>
36 #include <drm/drm_dp_helper.h>
37 #include <drm/drm_crtc.h>
40 #include "drm_crtc_helper_internal.h"
42 struct drm_dp_aux_dev
{
44 struct drm_dp_aux
*aux
;
50 #define DRM_AUX_MINORS 256
51 #define AUX_MAX_OFFSET (1 << 20)
53 static DEFINE_IDR(aux_idr
);
54 static DEFINE_MUTEX(aux_idr_mutex
);
55 static struct class *drm_dp_aux_dev_class
;
56 static int drm_dev_major
= -1;
58 static struct drm_dp_aux_dev
*drm_dp_aux_dev_get_by_minor(unsigned index
)
60 struct drm_dp_aux_dev
*aux_dev
= NULL
;
62 mutex_lock(&aux_idr_mutex
);
63 aux_dev
= idr_find(&aux_idr
, index
);
64 if (!kref_get_unless_zero(&aux_dev
->refcount
))
66 mutex_unlock(&aux_idr_mutex
);
71 static struct drm_dp_aux_dev
*alloc_drm_dp_aux_dev(struct drm_dp_aux
*aux
)
73 struct drm_dp_aux_dev
*aux_dev
;
76 aux_dev
= kzalloc(sizeof(*aux_dev
), GFP_KERNEL
);
78 return ERR_PTR(-ENOMEM
);
80 atomic_set(&aux_dev
->usecount
, 1);
81 kref_init(&aux_dev
->refcount
);
83 mutex_lock(&aux_idr_mutex
);
84 index
= idr_alloc_cyclic(&aux_idr
, aux_dev
, 0, DRM_AUX_MINORS
,
86 mutex_unlock(&aux_idr_mutex
);
89 return ERR_PTR(index
);
91 aux_dev
->index
= index
;
96 static void release_drm_dp_aux_dev(struct kref
*ref
)
98 struct drm_dp_aux_dev
*aux_dev
=
99 container_of(ref
, struct drm_dp_aux_dev
, refcount
);
104 static ssize_t
name_show(struct device
*dev
,
105 struct device_attribute
*attr
, char *buf
)
108 struct drm_dp_aux_dev
*aux_dev
=
109 drm_dp_aux_dev_get_by_minor(MINOR(dev
->devt
));
114 res
= sprintf(buf
, "%s\n", aux_dev
->aux
->name
);
115 kref_put(&aux_dev
->refcount
, release_drm_dp_aux_dev
);
119 static DEVICE_ATTR_RO(name
);
121 static struct attribute
*drm_dp_aux_attrs
[] = {
125 ATTRIBUTE_GROUPS(drm_dp_aux
);
127 static int auxdev_open(struct inode
*inode
, struct file
*file
)
129 unsigned int minor
= iminor(inode
);
130 struct drm_dp_aux_dev
*aux_dev
;
132 aux_dev
= drm_dp_aux_dev_get_by_minor(minor
);
136 file
->private_data
= aux_dev
;
140 static loff_t
auxdev_llseek(struct file
*file
, loff_t offset
, int whence
)
142 return fixed_size_llseek(file
, offset
, whence
, AUX_MAX_OFFSET
);
145 static ssize_t
auxdev_read_iter(struct kiocb
*iocb
, struct iov_iter
*to
)
147 struct drm_dp_aux_dev
*aux_dev
= iocb
->ki_filp
->private_data
;
148 loff_t pos
= iocb
->ki_pos
;
151 if (!atomic_inc_not_zero(&aux_dev
->usecount
))
154 iov_iter_truncate(to
, AUX_MAX_OFFSET
- pos
);
156 while (iov_iter_count(to
)) {
157 uint8_t buf
[DP_AUX_MAX_PAYLOAD_BYTES
];
158 ssize_t todo
= min(iov_iter_count(to
), sizeof(buf
));
160 if (signal_pending(current
)) {
165 res
= drm_dp_dpcd_read(aux_dev
->aux
, pos
, buf
, todo
);
169 if (copy_to_iter(buf
, res
, to
) != res
) {
177 if (pos
!= iocb
->ki_pos
)
178 res
= pos
- iocb
->ki_pos
;
181 atomic_dec(&aux_dev
->usecount
);
182 wake_up_atomic_t(&aux_dev
->usecount
);
186 static ssize_t
auxdev_write_iter(struct kiocb
*iocb
, struct iov_iter
*from
)
188 struct drm_dp_aux_dev
*aux_dev
= iocb
->ki_filp
->private_data
;
189 loff_t pos
= iocb
->ki_pos
;
192 if (!atomic_inc_not_zero(&aux_dev
->usecount
))
195 iov_iter_truncate(from
, AUX_MAX_OFFSET
- pos
);
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
));
201 if (signal_pending(current
)) {
206 if (!copy_from_iter_full(buf
, todo
, from
)) {
211 res
= drm_dp_dpcd_write(aux_dev
->aux
, pos
, buf
, todo
);
218 if (pos
!= iocb
->ki_pos
)
219 res
= pos
- iocb
->ki_pos
;
222 atomic_dec(&aux_dev
->usecount
);
223 wake_up_atomic_t(&aux_dev
->usecount
);
227 static int auxdev_release(struct inode
*inode
, struct file
*file
)
229 struct drm_dp_aux_dev
*aux_dev
= file
->private_data
;
231 kref_put(&aux_dev
->refcount
, release_drm_dp_aux_dev
);
235 static const struct file_operations auxdev_fops
= {
236 .owner
= THIS_MODULE
,
237 .llseek
= auxdev_llseek
,
238 .read_iter
= auxdev_read_iter
,
239 .write_iter
= auxdev_write_iter
,
241 .release
= auxdev_release
,
244 #define to_auxdev(d) container_of(d, struct drm_dp_aux_dev, aux)
246 static struct drm_dp_aux_dev
*drm_dp_aux_dev_get_by_aux(struct drm_dp_aux
*aux
)
248 struct drm_dp_aux_dev
*iter
, *aux_dev
= NULL
;
251 /* don't increase kref count here because this function should only be
252 * used by drm_dp_aux_unregister_devnode. Thus, it will always have at
253 * least one reference - the one that drm_dp_aux_register_devnode
256 mutex_lock(&aux_idr_mutex
);
257 idr_for_each_entry(&aux_idr
, iter
, id
) {
258 if (iter
->aux
== aux
) {
263 mutex_unlock(&aux_idr_mutex
);
267 void drm_dp_aux_unregister_devnode(struct drm_dp_aux
*aux
)
269 struct drm_dp_aux_dev
*aux_dev
;
272 aux_dev
= drm_dp_aux_dev_get_by_aux(aux
);
273 if (!aux_dev
) /* attach must have failed */
276 mutex_lock(&aux_idr_mutex
);
277 idr_remove(&aux_idr
, aux_dev
->index
);
278 mutex_unlock(&aux_idr_mutex
);
280 atomic_dec(&aux_dev
->usecount
);
281 wait_on_atomic_t(&aux_dev
->usecount
, atomic_t_wait
,
282 TASK_UNINTERRUPTIBLE
);
284 minor
= aux_dev
->index
;
286 device_destroy(drm_dp_aux_dev_class
,
287 MKDEV(drm_dev_major
, minor
));
289 DRM_DEBUG("drm_dp_aux_dev: aux [%s] unregistering\n", aux
->name
);
290 kref_put(&aux_dev
->refcount
, release_drm_dp_aux_dev
);
293 int drm_dp_aux_register_devnode(struct drm_dp_aux
*aux
)
295 struct drm_dp_aux_dev
*aux_dev
;
298 aux_dev
= alloc_drm_dp_aux_dev(aux
);
300 return PTR_ERR(aux_dev
);
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
);
311 DRM_DEBUG("drm_dp_aux_dev: aux [%s] registered as minor %d\n",
312 aux
->name
, aux_dev
->index
);
315 drm_dp_aux_unregister_devnode(aux
);
319 int drm_dp_aux_dev_init(void)
323 drm_dp_aux_dev_class
= class_create(THIS_MODULE
, "drm_dp_aux_dev");
324 if (IS_ERR(drm_dp_aux_dev_class
)) {
325 return PTR_ERR(drm_dp_aux_dev_class
);
327 drm_dp_aux_dev_class
->dev_groups
= drm_dp_aux_groups
;
329 res
= register_chrdev(0, "aux", &auxdev_fops
);
336 class_destroy(drm_dp_aux_dev_class
);
340 void drm_dp_aux_dev_exit(void)
342 unregister_chrdev(drm_dev_major
, "aux");
343 class_destroy(drm_dp_aux_dev_class
);