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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
162 res = drm_dp_dpcd_read(aux_dev->aux, *offset, localbuf, todo);
163 if (res <= 0) {
164 res = num_bytes_processed ? num_bytes_processed : res;
165 goto out;
166 }
167 if (__copy_to_user(buf + num_bytes_processed, localbuf, res)) {
168 res = num_bytes_processed ?
169 num_bytes_processed : -EFAULT;
170 goto out;
171 }
172 bytes_pending -= res;
173 *offset += res;
174 num_bytes_processed += res;
175 res = num_bytes_processed;
176 }
177
178out:
179 atomic_dec(&aux_dev->usecount);
180 wake_up_atomic_t(&aux_dev->usecount);
181 return res;
182}
183
184static ssize_t auxdev_write(struct file *file, const char __user *buf,
185 size_t count, loff_t *offset)
186{
187 size_t bytes_pending, num_bytes_processed = 0;
188 struct drm_dp_aux_dev *aux_dev = file->private_data;
189 ssize_t res = 0;
190
191 if (!atomic_inc_not_zero(&aux_dev->usecount))
192 return -ENODEV;
193
194 bytes_pending = min((loff_t)count, AUX_MAX_OFFSET - *offset);
195
196 if (!access_ok(VERIFY_READ, buf, bytes_pending)) {
197 res = -EFAULT;
198 goto out;
199 }
200
201 while (bytes_pending > 0) {
202 uint8_t localbuf[DP_AUX_MAX_PAYLOAD_BYTES];
203 ssize_t todo = min_t(size_t, bytes_pending, sizeof(localbuf));
204
205 if (__copy_from_user(localbuf,
206 buf + num_bytes_processed, todo)) {
207 res = num_bytes_processed ?
208 num_bytes_processed : -EFAULT;
209 goto out;
210 }
211
212 res = drm_dp_dpcd_write(aux_dev->aux, *offset, localbuf, todo);
213 if (res <= 0) {
214 res = num_bytes_processed ? num_bytes_processed : res;
215 goto out;
216 }
217 bytes_pending -= res;
218 *offset += res;
219 num_bytes_processed += res;
220 res = num_bytes_processed;
221 }
222
223out:
224 atomic_dec(&aux_dev->usecount);
225 wake_up_atomic_t(&aux_dev->usecount);
226 return res;
227}
228
229static int auxdev_release(struct inode *inode, struct file *file)
230{
231 struct drm_dp_aux_dev *aux_dev = file->private_data;
232
233 kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
234 return 0;
235}
236
237static const struct file_operations auxdev_fops = {
238 .owner = THIS_MODULE,
239 .llseek = auxdev_llseek,
240 .read = auxdev_read,
241 .write = auxdev_write,
242 .open = auxdev_open,
243 .release = auxdev_release,
244};
245
246#define to_auxdev(d) container_of(d, struct drm_dp_aux_dev, aux)
247
248static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_aux(struct drm_dp_aux *aux)
249{
250 struct drm_dp_aux_dev *iter, *aux_dev = NULL;
251 int id;
252
253
254
255
256
257
258 mutex_lock(&aux_idr_mutex);
259 idr_for_each_entry(&aux_idr, iter, id) {
260 if (iter->aux == aux) {
261 aux_dev = iter;
262 break;
263 }
264 }
265 mutex_unlock(&aux_idr_mutex);
266 return aux_dev;
267}
268
269static int auxdev_wait_atomic_t(atomic_t *p)
270{
271 schedule();
272 return 0;
273}
274
275
276
277
278
279
280void 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_on_atomic_t(&aux_dev->usecount, auxdev_wait_atomic_t,
295 TASK_UNINTERRUPTIBLE);
296
297 minor = aux_dev->index;
298 if (aux_dev->dev)
299 device_destroy(drm_dp_aux_dev_class,
300 MKDEV(drm_dev_major, minor));
301
302 DRM_DEBUG("drm_dp_aux_dev: aux [%s] unregistering\n", aux->name);
303 kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
304}
305EXPORT_SYMBOL(drm_dp_aux_unregister_devnode);
306
307
308
309
310
311
312
313int drm_dp_aux_register_devnode(struct drm_dp_aux *aux)
314{
315 struct drm_dp_aux_dev *aux_dev;
316 int res;
317
318 aux_dev = alloc_drm_dp_aux_dev(aux);
319 if (IS_ERR(aux_dev))
320 return PTR_ERR(aux_dev);
321
322 aux_dev->dev = device_create(drm_dp_aux_dev_class, aux->dev,
323 MKDEV(drm_dev_major, aux_dev->index), NULL,
324 "drm_dp_aux%d", aux_dev->index);
325 if (IS_ERR(aux_dev->dev)) {
326 res = PTR_ERR(aux_dev->dev);
327 aux_dev->dev = NULL;
328 goto error;
329 }
330
331 DRM_DEBUG("drm_dp_aux_dev: aux [%s] registered as minor %d\n",
332 aux->name, aux_dev->index);
333 return 0;
334error:
335 drm_dp_aux_unregister_devnode(aux);
336 return res;
337}
338EXPORT_SYMBOL(drm_dp_aux_register_devnode);
339
340int drm_dp_aux_dev_init(void)
341{
342 int res;
343
344 drm_dp_aux_dev_class = class_create(THIS_MODULE, "drm_dp_aux_dev");
345 if (IS_ERR(drm_dp_aux_dev_class)) {
346 res = PTR_ERR(drm_dp_aux_dev_class);
347 goto out;
348 }
349 drm_dp_aux_dev_class->dev_groups = drm_dp_aux_groups;
350
351 res = register_chrdev(0, "aux", &auxdev_fops);
352 if (res < 0)
353 goto out;
354 drm_dev_major = res;
355
356 return 0;
357out:
358 class_destroy(drm_dp_aux_dev_class);
359 return res;
360}
361EXPORT_SYMBOL(drm_dp_aux_dev_init);
362
363void drm_dp_aux_dev_exit(void)
364{
365 unregister_chrdev(drm_dev_major, "aux");
366 class_destroy(drm_dp_aux_dev_class);
367}
368EXPORT_SYMBOL(drm_dp_aux_dev_exit);
369
