blob: 734f86a345f628edab95c7ab3c8652a4d9927e7b [file] [log] [blame]
Rafael Antognollie94cb372016-01-21 15:10:19 -08001/*
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>
35#include <drm/drm_dp_helper.h>
36#include <drm/drm_crtc.h>
37#include <drm/drmP.h>
38
39struct drm_dp_aux_dev {
40 unsigned index;
41 struct drm_dp_aux *aux;
42 struct device *dev;
43 struct kref refcount;
44 atomic_t usecount;
45};
46
47#define DRM_AUX_MINORS 256
48#define AUX_MAX_OFFSET (1 << 20)
49static DEFINE_IDR(aux_idr);
50static DEFINE_MUTEX(aux_idr_mutex);
51static struct class *drm_dp_aux_dev_class;
52static int drm_dev_major = -1;
53
54static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_minor(unsigned index)
55{
56 struct drm_dp_aux_dev *aux_dev = NULL;
57
58 mutex_lock(&aux_idr_mutex);
59 aux_dev = idr_find(&aux_idr, index);
60 if (!kref_get_unless_zero(&aux_dev->refcount))
61 aux_dev = NULL;
62 mutex_unlock(&aux_idr_mutex);
63
64 return aux_dev;
65}
66
67static struct drm_dp_aux_dev *alloc_drm_dp_aux_dev(struct drm_dp_aux *aux)
68{
69 struct drm_dp_aux_dev *aux_dev;
70 int index;
71
72 aux_dev = kzalloc(sizeof(*aux_dev), GFP_KERNEL);
73 if (!aux_dev)
74 return ERR_PTR(-ENOMEM);
75 aux_dev->aux = aux;
76 atomic_set(&aux_dev->usecount, 1);
77 kref_init(&aux_dev->refcount);
78
79 mutex_lock(&aux_idr_mutex);
80 index = idr_alloc_cyclic(&aux_idr, aux_dev, 0, DRM_AUX_MINORS,
81 GFP_KERNEL);
82 mutex_unlock(&aux_idr_mutex);
83 if (index < 0) {
84 kfree(aux_dev);
85 return ERR_PTR(index);
86 }
87 aux_dev->index = index;
88
89 return aux_dev;
90}
91
92static void release_drm_dp_aux_dev(struct kref *ref)
93{
94 struct drm_dp_aux_dev *aux_dev =
95 container_of(ref, struct drm_dp_aux_dev, refcount);
96
97 kfree(aux_dev);
98}
99
100static ssize_t name_show(struct device *dev,
101 struct device_attribute *attr, char *buf)
102{
103 ssize_t res;
104 struct drm_dp_aux_dev *aux_dev =
105 drm_dp_aux_dev_get_by_minor(MINOR(dev->devt));
106
107 if (!aux_dev)
108 return -ENODEV;
109
110 res = sprintf(buf, "%s\n", aux_dev->aux->name);
111 kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
112
113 return res;
114}
115static DEVICE_ATTR_RO(name);
116
117static struct attribute *drm_dp_aux_attrs[] = {
118 &dev_attr_name.attr,
119 NULL,
120};
121ATTRIBUTE_GROUPS(drm_dp_aux);
122
123static int auxdev_open(struct inode *inode, struct file *file)
124{
125 unsigned int minor = iminor(inode);
126 struct drm_dp_aux_dev *aux_dev;
127
128 aux_dev = drm_dp_aux_dev_get_by_minor(minor);
129 if (!aux_dev)
130 return -ENODEV;
131
132 file->private_data = aux_dev;
133 return 0;
134}
135
136static loff_t auxdev_llseek(struct file *file, loff_t offset, int whence)
137{
138 return fixed_size_llseek(file, offset, whence, AUX_MAX_OFFSET);
139}
140
141static ssize_t auxdev_read(struct file *file, char __user *buf, size_t count,
142 loff_t *offset)
143{
144 size_t bytes_pending, num_bytes_processed = 0;
145 struct drm_dp_aux_dev *aux_dev = file->private_data;
146 ssize_t res = 0;
147
148 if (!atomic_inc_not_zero(&aux_dev->usecount))
149 return -ENODEV;
150
151 bytes_pending = min((loff_t)count, AUX_MAX_OFFSET - (*offset));
152
153 if (!access_ok(VERIFY_WRITE, buf, bytes_pending)) {
154 res = -EFAULT;
155 goto out;
156 }
157
158 while (bytes_pending > 0) {
159 uint8_t localbuf[DP_AUX_MAX_PAYLOAD_BYTES];
160 ssize_t todo = min_t(size_t, bytes_pending, sizeof(localbuf));
161
Ville Syrjälä36230cb2016-04-27 22:43:45 +0300162 if (signal_pending(current)) {
163 res = num_bytes_processed ?
164 num_bytes_processed : -ERESTARTSYS;
165 goto out;
166 }
167
Rafael Antognollie94cb372016-01-21 15:10:19 -0800168 res = drm_dp_dpcd_read(aux_dev->aux, *offset, localbuf, todo);
169 if (res <= 0) {
170 res = num_bytes_processed ? num_bytes_processed : res;
171 goto out;
172 }
173 if (__copy_to_user(buf + num_bytes_processed, localbuf, res)) {
174 res = num_bytes_processed ?
175 num_bytes_processed : -EFAULT;
176 goto out;
177 }
178 bytes_pending -= res;
179 *offset += res;
180 num_bytes_processed += res;
181 res = num_bytes_processed;
182 }
183
184out:
185 atomic_dec(&aux_dev->usecount);
186 wake_up_atomic_t(&aux_dev->usecount);
187 return res;
188}
189
190static ssize_t auxdev_write(struct file *file, const char __user *buf,
191 size_t count, loff_t *offset)
192{
193 size_t bytes_pending, num_bytes_processed = 0;
194 struct drm_dp_aux_dev *aux_dev = file->private_data;
195 ssize_t res = 0;
196
197 if (!atomic_inc_not_zero(&aux_dev->usecount))
198 return -ENODEV;
199
200 bytes_pending = min((loff_t)count, AUX_MAX_OFFSET - *offset);
201
202 if (!access_ok(VERIFY_READ, buf, bytes_pending)) {
203 res = -EFAULT;
204 goto out;
205 }
206
207 while (bytes_pending > 0) {
208 uint8_t localbuf[DP_AUX_MAX_PAYLOAD_BYTES];
209 ssize_t todo = min_t(size_t, bytes_pending, sizeof(localbuf));
210
Ville Syrjälä36230cb2016-04-27 22:43:45 +0300211 if (signal_pending(current)) {
212 res = num_bytes_processed ?
213 num_bytes_processed : -ERESTARTSYS;
214 goto out;
215 }
216
Rafael Antognollie94cb372016-01-21 15:10:19 -0800217 if (__copy_from_user(localbuf,
218 buf + num_bytes_processed, todo)) {
219 res = num_bytes_processed ?
220 num_bytes_processed : -EFAULT;
221 goto out;
222 }
223
224 res = drm_dp_dpcd_write(aux_dev->aux, *offset, localbuf, todo);
225 if (res <= 0) {
226 res = num_bytes_processed ? num_bytes_processed : res;
227 goto out;
228 }
229 bytes_pending -= res;
230 *offset += res;
231 num_bytes_processed += res;
232 res = num_bytes_processed;
233 }
234
235out:
236 atomic_dec(&aux_dev->usecount);
237 wake_up_atomic_t(&aux_dev->usecount);
238 return res;
239}
240
241static int auxdev_release(struct inode *inode, struct file *file)
242{
243 struct drm_dp_aux_dev *aux_dev = file->private_data;
244
245 kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
246 return 0;
247}
248
249static const struct file_operations auxdev_fops = {
250 .owner = THIS_MODULE,
251 .llseek = auxdev_llseek,
252 .read = auxdev_read,
253 .write = auxdev_write,
254 .open = auxdev_open,
255 .release = auxdev_release,
256};
257
258#define to_auxdev(d) container_of(d, struct drm_dp_aux_dev, aux)
259
260static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_aux(struct drm_dp_aux *aux)
261{
262 struct drm_dp_aux_dev *iter, *aux_dev = NULL;
263 int id;
264
265 /* don't increase kref count here because this function should only be
266 * used by drm_dp_aux_unregister_devnode. Thus, it will always have at
267 * least one reference - the one that drm_dp_aux_register_devnode
268 * created
269 */
270 mutex_lock(&aux_idr_mutex);
271 idr_for_each_entry(&aux_idr, iter, id) {
272 if (iter->aux == aux) {
273 aux_dev = iter;
274 break;
275 }
276 }
277 mutex_unlock(&aux_idr_mutex);
278 return aux_dev;
279}
280
281static int auxdev_wait_atomic_t(atomic_t *p)
282{
283 schedule();
284 return 0;
285}
286/**
287 * drm_dp_aux_unregister_devnode() - unregister a devnode for this aux channel
288 * @aux: DisplayPort AUX channel
289 *
290 * Returns 0 on success or a negative error code on failure.
291 */
292void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux)
293{
294 struct drm_dp_aux_dev *aux_dev;
295 unsigned int minor;
296
297 aux_dev = drm_dp_aux_dev_get_by_aux(aux);
298 if (!aux_dev) /* attach must have failed */
299 return;
300
301 mutex_lock(&aux_idr_mutex);
302 idr_remove(&aux_idr, aux_dev->index);
303 mutex_unlock(&aux_idr_mutex);
304
305 atomic_dec(&aux_dev->usecount);
306 wait_on_atomic_t(&aux_dev->usecount, auxdev_wait_atomic_t,
307 TASK_UNINTERRUPTIBLE);
308
309 minor = aux_dev->index;
310 if (aux_dev->dev)
311 device_destroy(drm_dp_aux_dev_class,
312 MKDEV(drm_dev_major, minor));
313
314 DRM_DEBUG("drm_dp_aux_dev: aux [%s] unregistering\n", aux->name);
315 kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
316}
317EXPORT_SYMBOL(drm_dp_aux_unregister_devnode);
318
319/**
320 * drm_dp_aux_register_devnode() - register a devnode for this aux channel
321 * @aux: DisplayPort AUX channel
322 *
323 * Returns 0 on success or a negative error code on failure.
324 */
325int drm_dp_aux_register_devnode(struct drm_dp_aux *aux)
326{
327 struct drm_dp_aux_dev *aux_dev;
328 int res;
329
330 aux_dev = alloc_drm_dp_aux_dev(aux);
331 if (IS_ERR(aux_dev))
332 return PTR_ERR(aux_dev);
333
334 aux_dev->dev = device_create(drm_dp_aux_dev_class, aux->dev,
335 MKDEV(drm_dev_major, aux_dev->index), NULL,
336 "drm_dp_aux%d", aux_dev->index);
337 if (IS_ERR(aux_dev->dev)) {
338 res = PTR_ERR(aux_dev->dev);
339 aux_dev->dev = NULL;
340 goto error;
341 }
342
343 DRM_DEBUG("drm_dp_aux_dev: aux [%s] registered as minor %d\n",
344 aux->name, aux_dev->index);
345 return 0;
346error:
347 drm_dp_aux_unregister_devnode(aux);
348 return res;
349}
350EXPORT_SYMBOL(drm_dp_aux_register_devnode);
351
352int drm_dp_aux_dev_init(void)
353{
354 int res;
355
356 drm_dp_aux_dev_class = class_create(THIS_MODULE, "drm_dp_aux_dev");
357 if (IS_ERR(drm_dp_aux_dev_class)) {
Alexey Khoroshilovda82ee92016-06-30 00:52:15 +0300358 return PTR_ERR(drm_dp_aux_dev_class);
Rafael Antognollie94cb372016-01-21 15:10:19 -0800359 }
360 drm_dp_aux_dev_class->dev_groups = drm_dp_aux_groups;
361
362 res = register_chrdev(0, "aux", &auxdev_fops);
363 if (res < 0)
364 goto out;
365 drm_dev_major = res;
366
367 return 0;
368out:
369 class_destroy(drm_dp_aux_dev_class);
370 return res;
371}
372EXPORT_SYMBOL(drm_dp_aux_dev_init);
373
374void drm_dp_aux_dev_exit(void)
375{
376 unregister_chrdev(drm_dev_major, "aux");
377 class_destroy(drm_dp_aux_dev_class);
378}
379EXPORT_SYMBOL(drm_dp_aux_dev_exit);