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>
35 #include <linux/uio.h>
36 #include <drm/drm_dp_helper.h>
37 #include <drm/drm_crtc.h>
38 #include <drm/drmP.h>
39
40 #include "drm_crtc_helper_internal.h"
41
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
drm_dp_aux_dev_get_by_minor(unsigned index)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
alloc_drm_dp_aux_dev(struct drm_dp_aux * aux)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
release_drm_dp_aux_dev(struct kref * ref)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
name_show(struct device * dev,struct device_attribute * attr,char * buf)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
auxdev_open(struct inode * inode,struct file * file)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
auxdev_llseek(struct file * file,loff_t offset,int whence)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
auxdev_read_iter(struct kiocb * iocb,struct iov_iter * to)144 static ssize_t auxdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
145 {
146 struct drm_dp_aux_dev *aux_dev = iocb->ki_filp->private_data;
147 loff_t pos = iocb->ki_pos;
148 ssize_t res = 0;
149
150 if (!atomic_inc_not_zero(&aux_dev->usecount))
151 return -ENODEV;
152
153 iov_iter_truncate(to, AUX_MAX_OFFSET - pos);
154
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));
158
159 if (signal_pending(current)) {
160 res = -ERESTARTSYS;
161 break;
162 }
163
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;
171 }
172
173 pos += res;
174 }
175
176 if (pos != iocb->ki_pos)
177 res = pos - iocb->ki_pos;
178 iocb->ki_pos = pos;
179
180 if (atomic_dec_and_test(&aux_dev->usecount))
181 wake_up_var(&aux_dev->usecount);
182
183 return res;
184 }
185
auxdev_write_iter(struct kiocb * iocb,struct iov_iter * from)186 static ssize_t auxdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
187 {
188 struct drm_dp_aux_dev *aux_dev = iocb->ki_filp->private_data;
189 loff_t pos = iocb->ki_pos;
190 ssize_t res = 0;
191
192 if (!atomic_inc_not_zero(&aux_dev->usecount))
193 return -ENODEV;
194
195 iov_iter_truncate(from, AUX_MAX_OFFSET - pos);
196
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));
200
201 if (signal_pending(current)) {
202 res = -ERESTARTSYS;
203 break;
204 }
205
206 if (!copy_from_iter_full(buf, todo, from)) {
207 res = -EFAULT;
208 break;
209 }
210
211 res = drm_dp_dpcd_write(aux_dev->aux, pos, buf, todo);
212 if (res <= 0)
213 break;
214
215 pos += res;
216 }
217
218 if (pos != iocb->ki_pos)
219 res = pos - iocb->ki_pos;
220 iocb->ki_pos = pos;
221
222 if (atomic_dec_and_test(&aux_dev->usecount))
223 wake_up_var(&aux_dev->usecount);
224
225 return res;
226 }
227
auxdev_release(struct inode * inode,struct file * file)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,
239 .read_iter = auxdev_read_iter,
240 .write_iter = auxdev_write_iter,
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
drm_dp_aux_dev_get_by_aux(struct drm_dp_aux * aux)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
drm_dp_aux_unregister_devnode(struct drm_dp_aux * aux)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);
282 wait_var_event(&aux_dev->usecount, !atomic_read(&aux_dev->usecount));
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 }
292
drm_dp_aux_register_devnode(struct drm_dp_aux * aux)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 }
318
drm_dp_aux_dev_init(void)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)) {
325 return PTR_ERR(drm_dp_aux_dev_class);
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 }
339
drm_dp_aux_dev_exit(void)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 }
345
