This source file includes following definitions.
- drm_dp_aux_dev_get_by_minor
- alloc_drm_dp_aux_dev
- release_drm_dp_aux_dev
- name_show
- auxdev_open
- auxdev_llseek
- auxdev_read_iter
- auxdev_write_iter
- auxdev_release
- drm_dp_aux_dev_get_by_aux
- drm_dp_aux_unregister_devnode
- drm_dp_aux_register_devnode
- drm_dp_aux_dev_init
- drm_dp_aux_dev_exit
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28 #include <linux/device.h>
29 #include <linux/fs.h>
30 #include <linux/init.h>
31 #include <linux/kernel.h>
32 #include <linux/module.h>
33 #include <linux/sched/signal.h>
34 #include <linux/slab.h>
35 #include <linux/uaccess.h>
36 #include <linux/uio.h>
37
38 #include <drm/drm_crtc.h>
39 #include <drm/drm_dp_helper.h>
40 #include <drm/drm_dp_mst_helper.h>
41 #include <drm/drm_print.h>
42
43 #include "drm_crtc_helper_internal.h"
44
45 struct drm_dp_aux_dev {
46 unsigned index;
47 struct drm_dp_aux *aux;
48 struct device *dev;
49 struct kref refcount;
50 atomic_t usecount;
51 };
52
53 #define DRM_AUX_MINORS 256
54 #define AUX_MAX_OFFSET (1 << 20)
55 static DEFINE_IDR(aux_idr);
56 static DEFINE_MUTEX(aux_idr_mutex);
57 static struct class *drm_dp_aux_dev_class;
58 static int drm_dev_major = -1;
59
60 static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_minor(unsigned index)
61 {
62 struct drm_dp_aux_dev *aux_dev = NULL;
63
64 mutex_lock(&aux_idr_mutex);
65 aux_dev = idr_find(&aux_idr, index);
66 if (!kref_get_unless_zero(&aux_dev->refcount))
67 aux_dev = NULL;
68 mutex_unlock(&aux_idr_mutex);
69
70 return aux_dev;
71 }
72
73 static struct drm_dp_aux_dev *alloc_drm_dp_aux_dev(struct drm_dp_aux *aux)
74 {
75 struct drm_dp_aux_dev *aux_dev;
76 int index;
77
78 aux_dev = kzalloc(sizeof(*aux_dev), GFP_KERNEL);
79 if (!aux_dev)
80 return ERR_PTR(-ENOMEM);
81 aux_dev->aux = aux;
82 atomic_set(&aux_dev->usecount, 1);
83 kref_init(&aux_dev->refcount);
84
85 mutex_lock(&aux_idr_mutex);
86 index = idr_alloc(&aux_idr, aux_dev, 0, DRM_AUX_MINORS, 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
146 static ssize_t auxdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
147 {
148 struct drm_dp_aux_dev *aux_dev = iocb->ki_filp->private_data;
149 loff_t pos = iocb->ki_pos;
150 ssize_t res = 0;
151
152 if (!atomic_inc_not_zero(&aux_dev->usecount))
153 return -ENODEV;
154
155 iov_iter_truncate(to, AUX_MAX_OFFSET - pos);
156
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));
160
161 if (signal_pending(current)) {
162 res = -ERESTARTSYS;
163 break;
164 }
165
166 if (aux_dev->aux->is_remote)
167 res = drm_dp_mst_dpcd_read(aux_dev->aux, pos, buf,
168 todo);
169 else
170 res = drm_dp_dpcd_read(aux_dev->aux, pos, buf, todo);
171
172 if (res <= 0)
173 break;
174
175 if (copy_to_iter(buf, res, to) != res) {
176 res = -EFAULT;
177 break;
178 }
179
180 pos += res;
181 }
182
183 if (pos != iocb->ki_pos)
184 res = pos - iocb->ki_pos;
185 iocb->ki_pos = pos;
186
187 if (atomic_dec_and_test(&aux_dev->usecount))
188 wake_up_var(&aux_dev->usecount);
189
190 return res;
191 }
192
193 static ssize_t auxdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
194 {
195 struct drm_dp_aux_dev *aux_dev = iocb->ki_filp->private_data;
196 loff_t pos = iocb->ki_pos;
197 ssize_t res = 0;
198
199 if (!atomic_inc_not_zero(&aux_dev->usecount))
200 return -ENODEV;
201
202 iov_iter_truncate(from, AUX_MAX_OFFSET - pos);
203
204 while (iov_iter_count(from)) {
205 uint8_t buf[DP_AUX_MAX_PAYLOAD_BYTES];
206 ssize_t todo = min(iov_iter_count(from), sizeof(buf));
207
208 if (signal_pending(current)) {
209 res = -ERESTARTSYS;
210 break;
211 }
212
213 if (!copy_from_iter_full(buf, todo, from)) {
214 res = -EFAULT;
215 break;
216 }
217
218 if (aux_dev->aux->is_remote)
219 res = drm_dp_mst_dpcd_write(aux_dev->aux, pos, buf,
220 todo);
221 else
222 res = drm_dp_dpcd_write(aux_dev->aux, pos, buf, todo);
223
224 if (res <= 0)
225 break;
226
227 pos += res;
228 }
229
230 if (pos != iocb->ki_pos)
231 res = pos - iocb->ki_pos;
232 iocb->ki_pos = pos;
233
234 if (atomic_dec_and_test(&aux_dev->usecount))
235 wake_up_var(&aux_dev->usecount);
236
237 return res;
238 }
239
240 static int auxdev_release(struct inode *inode, struct file *file)
241 {
242 struct drm_dp_aux_dev *aux_dev = file->private_data;
243
244 kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
245 return 0;
246 }
247
248 static const struct file_operations auxdev_fops = {
249 .owner = THIS_MODULE,
250 .llseek = auxdev_llseek,
251 .read_iter = auxdev_read_iter,
252 .write_iter = auxdev_write_iter,
253 .open = auxdev_open,
254 .release = auxdev_release,
255 };
256
257 #define to_auxdev(d) container_of(d, struct drm_dp_aux_dev, aux)
258
259 static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_aux(struct drm_dp_aux *aux)
260 {
261 struct drm_dp_aux_dev *iter, *aux_dev = NULL;
262 int id;
263
264
265
266
267
268
269 mutex_lock(&aux_idr_mutex);
270 idr_for_each_entry(&aux_idr, iter, id) {
271 if (iter->aux == aux) {
272 aux_dev = iter;
273 break;
274 }
275 }
276 mutex_unlock(&aux_idr_mutex);
277 return aux_dev;
278 }
279
280 void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux)
281 {
282 struct drm_dp_aux_dev *aux_dev;
283 unsigned int minor;
284
285 aux_dev = drm_dp_aux_dev_get_by_aux(aux);
286 if (!aux_dev)
287 return;
288
289 mutex_lock(&aux_idr_mutex);
290 idr_remove(&aux_idr, aux_dev->index);
291 mutex_unlock(&aux_idr_mutex);
292
293 atomic_dec(&aux_dev->usecount);
294 wait_var_event(&aux_dev->usecount, !atomic_read(&aux_dev->usecount));
295
296 minor = aux_dev->index;
297 if (aux_dev->dev)
298 device_destroy(drm_dp_aux_dev_class,
299 MKDEV(drm_dev_major, minor));
300
301 DRM_DEBUG("drm_dp_aux_dev: aux [%s] unregistering\n", aux->name);
302 kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
303 }
304
305 int drm_dp_aux_register_devnode(struct drm_dp_aux *aux)
306 {
307 struct drm_dp_aux_dev *aux_dev;
308 int res;
309
310 aux_dev = alloc_drm_dp_aux_dev(aux);
311 if (IS_ERR(aux_dev))
312 return PTR_ERR(aux_dev);
313
314 aux_dev->dev = device_create(drm_dp_aux_dev_class, aux->dev,
315 MKDEV(drm_dev_major, aux_dev->index), NULL,
316 "drm_dp_aux%d", aux_dev->index);
317 if (IS_ERR(aux_dev->dev)) {
318 res = PTR_ERR(aux_dev->dev);
319 aux_dev->dev = NULL;
320 goto error;
321 }
322
323 DRM_DEBUG("drm_dp_aux_dev: aux [%s] registered as minor %d\n",
324 aux->name, aux_dev->index);
325 return 0;
326 error:
327 drm_dp_aux_unregister_devnode(aux);
328 return res;
329 }
330
331 int drm_dp_aux_dev_init(void)
332 {
333 int res;
334
335 drm_dp_aux_dev_class = class_create(THIS_MODULE, "drm_dp_aux_dev");
336 if (IS_ERR(drm_dp_aux_dev_class)) {
337 return PTR_ERR(drm_dp_aux_dev_class);
338 }
339 drm_dp_aux_dev_class->dev_groups = drm_dp_aux_groups;
340
341 res = register_chrdev(0, "aux", &auxdev_fops);
342 if (res < 0)
343 goto out;
344 drm_dev_major = res;
345
346 return 0;
347 out:
348 class_destroy(drm_dp_aux_dev_class);
349 return res;
350 }
351
352 void drm_dp_aux_dev_exit(void)
353 {
354 unregister_chrdev(drm_dev_major, "aux");
355 class_destroy(drm_dp_aux_dev_class);
356 }