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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
39#include "drm_crtc_helper_internal.h"
40
41struct drm_dp_aux_dev {
42 unsigned index;
43 struct drm_dp_aux *aux;
44 struct device *dev;
45 struct kref refcount;
46 atomic_t usecount;
47};
48
49#define DRM_AUX_MINORS 256
50#define AUX_MAX_OFFSET (1 << 20)
51static DEFINE_IDR(aux_idr);
52static DEFINE_MUTEX(aux_idr_mutex);
53static struct class *drm_dp_aux_dev_class;
54static int drm_dev_major = -1;
55
56static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_minor(unsigned index)
57{
58 struct drm_dp_aux_dev *aux_dev = NULL;
59
60 mutex_lock(&aux_idr_mutex);
61 aux_dev = idr_find(&aux_idr, index);
62 if (!kref_get_unless_zero(&aux_dev->refcount))
63 aux_dev = NULL;
64 mutex_unlock(&aux_idr_mutex);
65
66 return aux_dev;
67}
68
69static struct drm_dp_aux_dev *alloc_drm_dp_aux_dev(struct drm_dp_aux *aux)
70{
71 struct drm_dp_aux_dev *aux_dev;
72 int index;
73
74 aux_dev = kzalloc(sizeof(*aux_dev), GFP_KERNEL);
75 if (!aux_dev)
76 return ERR_PTR(-ENOMEM);
77 aux_dev->aux = aux;
78 atomic_set(&aux_dev->usecount, 1);
79 kref_init(&aux_dev->refcount);
80
81 mutex_lock(&aux_idr_mutex);
82 index = idr_alloc_cyclic(&aux_idr, aux_dev, 0, DRM_AUX_MINORS,
83 GFP_KERNEL);
84 mutex_unlock(&aux_idr_mutex);
85 if (index < 0) {
86 kfree(aux_dev);
87 return ERR_PTR(index);
88 }
89 aux_dev->index = index;
90
91 return aux_dev;
92}
93
94static void release_drm_dp_aux_dev(struct kref *ref)
95{
96 struct drm_dp_aux_dev *aux_dev =
97 container_of(ref, struct drm_dp_aux_dev, refcount);
98
99 kfree(aux_dev);
100}
101
102static ssize_t name_show(struct device *dev,
103 struct device_attribute *attr, char *buf)
104{
105 ssize_t res;
106 struct drm_dp_aux_dev *aux_dev =
107 drm_dp_aux_dev_get_by_minor(MINOR(dev->devt));
108
109 if (!aux_dev)
110 return -ENODEV;
111
112 res = sprintf(buf, "%s\n", aux_dev->aux->name);
113 kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
114
115 return res;
116}
117static DEVICE_ATTR_RO(name);
118
119static struct attribute *drm_dp_aux_attrs[] = {
120 &dev_attr_name.attr,
121 NULL,
122};
123ATTRIBUTE_GROUPS(drm_dp_aux);
124
125static int auxdev_open(struct inode *inode, struct file *file)
126{
127 unsigned int minor = iminor(inode);
128 struct drm_dp_aux_dev *aux_dev;
129
130 aux_dev = drm_dp_aux_dev_get_by_minor(minor);
131 if (!aux_dev)
132 return -ENODEV;
133
134 file->private_data = aux_dev;
135 return 0;
136}
137
138static loff_t auxdev_llseek(struct file *file, loff_t offset, int whence)
139{
140 return fixed_size_llseek(file, offset, whence, AUX_MAX_OFFSET);
141}
142
143static ssize_t auxdev_read(struct file *file, char __user *buf, size_t count,
144 loff_t *offset)
145{
146 size_t bytes_pending, num_bytes_processed = 0;
147 struct drm_dp_aux_dev *aux_dev = file->private_data;
148 ssize_t res = 0;
149
150 if (!atomic_inc_not_zero(&aux_dev->usecount))
151 return -ENODEV;
152
153 bytes_pending = min((loff_t)count, AUX_MAX_OFFSET - (*offset));
154
155 if (!access_ok(VERIFY_WRITE, buf, bytes_pending)) {
156 res = -EFAULT;
157 goto out;
158 }
159
160 while (bytes_pending > 0) {
161 uint8_t localbuf[DP_AUX_MAX_PAYLOAD_BYTES];
162 ssize_t todo = min_t(size_t, bytes_pending, sizeof(localbuf));
163
164 if (signal_pending(current)) {
165 res = num_bytes_processed ?
166 num_bytes_processed : -ERESTARTSYS;
167 goto out;
168 }
169
170 res = drm_dp_dpcd_read(aux_dev->aux, *offset, localbuf, todo);
171 if (res <= 0) {
172 res = num_bytes_processed ? num_bytes_processed : res;
173 goto out;
174 }
175 if (__copy_to_user(buf + num_bytes_processed, localbuf, res)) {
176 res = num_bytes_processed ?
177 num_bytes_processed : -EFAULT;
178 goto out;
179 }
180 bytes_pending -= res;
181 *offset += res;
182 num_bytes_processed += res;
183 res = num_bytes_processed;
184 }
185
186out:
187 atomic_dec(&aux_dev->usecount);
188 wake_up_atomic_t(&aux_dev->usecount);
189 return res;
190}
191
192static ssize_t auxdev_write(struct file *file, const char __user *buf,
193 size_t count, loff_t *offset)
194{
195 size_t bytes_pending, num_bytes_processed = 0;
196 struct drm_dp_aux_dev *aux_dev = file->private_data;
197 ssize_t res = 0;
198
199 if (!atomic_inc_not_zero(&aux_dev->usecount))
200 return -ENODEV;
201
202 bytes_pending = min((loff_t)count, AUX_MAX_OFFSET - *offset);
203
204 if (!access_ok(VERIFY_READ, buf, bytes_pending)) {
205 res = -EFAULT;
206 goto out;
207 }
208
209 while (bytes_pending > 0) {
210 uint8_t localbuf[DP_AUX_MAX_PAYLOAD_BYTES];
211 ssize_t todo = min_t(size_t, bytes_pending, sizeof(localbuf));
212
213 if (signal_pending(current)) {
214 res = num_bytes_processed ?
215 num_bytes_processed : -ERESTARTSYS;
216 goto out;
217 }
218
219 if (__copy_from_user(localbuf,
220 buf + num_bytes_processed, todo)) {
221 res = num_bytes_processed ?
222 num_bytes_processed : -EFAULT;
223 goto out;
224 }
225
226 res = drm_dp_dpcd_write(aux_dev->aux, *offset, localbuf, todo);
227 if (res <= 0) {
228 res = num_bytes_processed ? num_bytes_processed : res;
229 goto out;
230 }
231 bytes_pending -= res;
232 *offset += res;
233 num_bytes_processed += res;
234 res = num_bytes_processed;
235 }
236
237out:
238 atomic_dec(&aux_dev->usecount);
239 wake_up_atomic_t(&aux_dev->usecount);
240 return res;
241}
242
243static int auxdev_release(struct inode *inode, struct file *file)
244{
245 struct drm_dp_aux_dev *aux_dev = file->private_data;
246
247 kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
248 return 0;
249}
250
251static const struct file_operations auxdev_fops = {
252 .owner = THIS_MODULE,
253 .llseek = auxdev_llseek,
254 .read = auxdev_read,
255 .write = auxdev_write,
256 .open = auxdev_open,
257 .release = auxdev_release,
258};
259
260#define to_auxdev(d) container_of(d, struct drm_dp_aux_dev, aux)
261
262static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_aux(struct drm_dp_aux *aux)
263{
264 struct drm_dp_aux_dev *iter, *aux_dev = NULL;
265 int id;
266
267
268
269
270
271
272 mutex_lock(&aux_idr_mutex);
273 idr_for_each_entry(&aux_idr, iter, id) {
274 if (iter->aux == aux) {
275 aux_dev = iter;
276 break;
277 }
278 }
279 mutex_unlock(&aux_idr_mutex);
280 return aux_dev;
281}
282
283static int auxdev_wait_atomic_t(atomic_t *p)
284{
285 schedule();
286 return 0;
287}
288
289void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux)
290{
291 struct drm_dp_aux_dev *aux_dev;
292 unsigned int minor;
293
294 aux_dev = drm_dp_aux_dev_get_by_aux(aux);
295 if (!aux_dev)
296 return;
297
298 mutex_lock(&aux_idr_mutex);
299 idr_remove(&aux_idr, aux_dev->index);
300 mutex_unlock(&aux_idr_mutex);
301
302 atomic_dec(&aux_dev->usecount);
303 wait_on_atomic_t(&aux_dev->usecount, auxdev_wait_atomic_t,
304 TASK_UNINTERRUPTIBLE);
305
306 minor = aux_dev->index;
307 if (aux_dev->dev)
308 device_destroy(drm_dp_aux_dev_class,
309 MKDEV(drm_dev_major, minor));
310
311 DRM_DEBUG("drm_dp_aux_dev: aux [%s] unregistering\n", aux->name);
312 kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
313}
314
315int drm_dp_aux_register_devnode(struct drm_dp_aux *aux)
316{
317 struct drm_dp_aux_dev *aux_dev;
318 int res;
319
320 aux_dev = alloc_drm_dp_aux_dev(aux);
321 if (IS_ERR(aux_dev))
322 return PTR_ERR(aux_dev);
323
324 aux_dev->dev = device_create(drm_dp_aux_dev_class, aux->dev,
325 MKDEV(drm_dev_major, aux_dev->index), NULL,
326 "drm_dp_aux%d", aux_dev->index);
327 if (IS_ERR(aux_dev->dev)) {
328 res = PTR_ERR(aux_dev->dev);
329 aux_dev->dev = NULL;
330 goto error;
331 }
332
333 DRM_DEBUG("drm_dp_aux_dev: aux [%s] registered as minor %d\n",
334 aux->name, aux_dev->index);
335 return 0;
336error:
337 drm_dp_aux_unregister_devnode(aux);
338 return res;
339}
340
341int drm_dp_aux_dev_init(void)
342{
343 int res;
344
345 drm_dp_aux_dev_class = class_create(THIS_MODULE, "drm_dp_aux_dev");
346 if (IS_ERR(drm_dp_aux_dev_class)) {
347 return PTR_ERR(drm_dp_aux_dev_class);
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}
361
362void drm_dp_aux_dev_exit(void)
363{
364 unregister_chrdev(drm_dev_major, "aux");
365 class_destroy(drm_dp_aux_dev_class);
366}
367
