1 /*
2 * Copyright © 2008 Intel Corporation
3 * Copyright © 2016 Collabora Ltd
4 *
5 * Permission is hereby granted, free of charge, to any person obtaining a
6 * copy of this software and associated documentation files (the "Software"),
7 * to deal in the Software without restriction, including without limitation
8 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
9 * and/or sell copies of the Software, and to permit persons to whom the
10 * Software is furnished to do so, subject to the following conditions:
11 *
12 * The above copyright notice and this permission notice (including the next
13 * paragraph) shall be included in all copies or substantial portions of the
14 * Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
21 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
22 * IN THE SOFTWARE.
23 *
24 * Based on code from the i915 driver.
25 * Original author: Damien Lespiau <damien.lespiau@intel.com>
26 *
27 */
28
29 #include <linux/circ_buf.h>
30 #include <linux/ctype.h>
31 #include <linux/debugfs.h>
32 #include <drm/drmP.h>
33 #include "drm_internal.h"
34
35 /**
36 * DOC: CRC ABI
37 *
38 * DRM device drivers can provide to userspace CRC information of each frame as
39 * it reached a given hardware component (a CRC sampling "source").
40 *
41 * Userspace can control generation of CRCs in a given CRTC by writing to the
42 * file dri/0/crtc-N/crc/control in debugfs, with N being the index of the CRTC.
43 * Accepted values are source names (which are driver-specific) and the "auto"
44 * keyword, which will let the driver select a default source of frame CRCs
45 * for this CRTC.
46 *
47 * Once frame CRC generation is enabled, userspace can capture them by reading
48 * the dri/0/crtc-N/crc/data file. Each line in that file contains the frame
49 * number in the first field and then a number of unsigned integer fields
50 * containing the CRC data. Fields are separated by a single space and the number
51 * of CRC fields is source-specific.
52 *
53 * Note that though in some cases the CRC is computed in a specified way and on
54 * the frame contents as supplied by userspace (eDP 1.3), in general the CRC
55 * computation is performed in an unspecified way and on frame contents that have
56 * been already processed in also an unspecified way and thus userspace cannot
57 * rely on being able to generate matching CRC values for the frame contents that
58 * it submits. In this general case, the maximum userspace can do is to compare
59 * the reported CRCs of frames that should have the same contents.
60 *
61 * On the driver side the implementation effort is minimal, drivers only need to
62 * implement &drm_crtc_funcs.set_crc_source. The debugfs files are automatically
63 * set up if that vfunc is set. CRC samples need to be captured in the driver by
64 * calling drm_crtc_add_crc_entry().
65 */
66
crc_control_show(struct seq_file * m,void * data)67 static int crc_control_show(struct seq_file *m, void *data)
68 {
69 struct drm_crtc *crtc = m->private;
70
71 seq_printf(m, "%s\n", crtc->crc.source);
72
73 return 0;
74 }
75
crc_control_open(struct inode * inode,struct file * file)76 static int crc_control_open(struct inode *inode, struct file *file)
77 {
78 struct drm_crtc *crtc = inode->i_private;
79
80 return single_open(file, crc_control_show, crtc);
81 }
82
crc_control_write(struct file * file,const char __user * ubuf,size_t len,loff_t * offp)83 static ssize_t crc_control_write(struct file *file, const char __user *ubuf,
84 size_t len, loff_t *offp)
85 {
86 struct seq_file *m = file->private_data;
87 struct drm_crtc *crtc = m->private;
88 struct drm_crtc_crc *crc = &crtc->crc;
89 char *source;
90
91 if (len == 0)
92 return 0;
93
94 if (len > PAGE_SIZE - 1) {
95 DRM_DEBUG_KMS("Expected < %lu bytes into crtc crc control\n",
96 PAGE_SIZE);
97 return -E2BIG;
98 }
99
100 source = memdup_user_nul(ubuf, len);
101 if (IS_ERR(source))
102 return PTR_ERR(source);
103
104 if (source[len - 1] == '\n')
105 source[len - 1] = '\0';
106
107 spin_lock_irq(&crc->lock);
108
109 if (crc->opened) {
110 spin_unlock_irq(&crc->lock);
111 kfree(source);
112 return -EBUSY;
113 }
114
115 kfree(crc->source);
116 crc->source = source;
117
118 spin_unlock_irq(&crc->lock);
119
120 *offp += len;
121 return len;
122 }
123
124 static const struct file_operations drm_crtc_crc_control_fops = {
125 .owner = THIS_MODULE,
126 .open = crc_control_open,
127 .read = seq_read,
128 .llseek = seq_lseek,
129 .release = single_release,
130 .write = crc_control_write
131 };
132
crtc_crc_data_count(struct drm_crtc_crc * crc)133 static int crtc_crc_data_count(struct drm_crtc_crc *crc)
134 {
135 assert_spin_locked(&crc->lock);
136 return CIRC_CNT(crc->head, crc->tail, DRM_CRC_ENTRIES_NR);
137 }
138
crtc_crc_cleanup(struct drm_crtc_crc * crc)139 static void crtc_crc_cleanup(struct drm_crtc_crc *crc)
140 {
141 kfree(crc->entries);
142 crc->overflow = false;
143 crc->entries = NULL;
144 crc->head = 0;
145 crc->tail = 0;
146 crc->values_cnt = 0;
147 crc->opened = false;
148 }
149
crtc_crc_open(struct inode * inode,struct file * filep)150 static int crtc_crc_open(struct inode *inode, struct file *filep)
151 {
152 struct drm_crtc *crtc = inode->i_private;
153 struct drm_crtc_crc *crc = &crtc->crc;
154 struct drm_crtc_crc_entry *entries = NULL;
155 size_t values_cnt;
156 int ret = 0;
157
158 if (drm_drv_uses_atomic_modeset(crtc->dev)) {
159 ret = drm_modeset_lock_interruptible(&crtc->mutex, NULL);
160 if (ret)
161 return ret;
162
163 if (!crtc->state->active)
164 ret = -EIO;
165 drm_modeset_unlock(&crtc->mutex);
166
167 if (ret)
168 return ret;
169 }
170
171 spin_lock_irq(&crc->lock);
172 if (!crc->opened)
173 crc->opened = true;
174 else
175 ret = -EBUSY;
176 spin_unlock_irq(&crc->lock);
177
178 if (ret)
179 return ret;
180
181 ret = crtc->funcs->set_crc_source(crtc, crc->source, &values_cnt);
182 if (ret)
183 goto err;
184
185 if (WARN_ON(values_cnt > DRM_MAX_CRC_NR)) {
186 ret = -EINVAL;
187 goto err_disable;
188 }
189
190 if (WARN_ON(values_cnt == 0)) {
191 ret = -EINVAL;
192 goto err_disable;
193 }
194
195 entries = kcalloc(DRM_CRC_ENTRIES_NR, sizeof(*entries), GFP_KERNEL);
196 if (!entries) {
197 ret = -ENOMEM;
198 goto err_disable;
199 }
200
201 spin_lock_irq(&crc->lock);
202 crc->entries = entries;
203 crc->values_cnt = values_cnt;
204
205 /*
206 * Only return once we got a first frame, so userspace doesn't have to
207 * guess when this particular piece of HW will be ready to start
208 * generating CRCs.
209 */
210 ret = wait_event_interruptible_lock_irq(crc->wq,
211 crtc_crc_data_count(crc),
212 crc->lock);
213 spin_unlock_irq(&crc->lock);
214
215 if (ret)
216 goto err_disable;
217
218 return 0;
219
220 err_disable:
221 crtc->funcs->set_crc_source(crtc, NULL, &values_cnt);
222 err:
223 spin_lock_irq(&crc->lock);
224 crtc_crc_cleanup(crc);
225 spin_unlock_irq(&crc->lock);
226 return ret;
227 }
228
crtc_crc_release(struct inode * inode,struct file * filep)229 static int crtc_crc_release(struct inode *inode, struct file *filep)
230 {
231 struct drm_crtc *crtc = filep->f_inode->i_private;
232 struct drm_crtc_crc *crc = &crtc->crc;
233 size_t values_cnt;
234
235 crtc->funcs->set_crc_source(crtc, NULL, &values_cnt);
236
237 spin_lock_irq(&crc->lock);
238 crtc_crc_cleanup(crc);
239 spin_unlock_irq(&crc->lock);
240
241 return 0;
242 }
243
244 /*
245 * 1 frame field of 10 chars plus a number of CRC fields of 10 chars each, space
246 * separated, with a newline at the end and null-terminated.
247 */
248 #define LINE_LEN(values_cnt) (10 + 11 * values_cnt + 1 + 1)
249 #define MAX_LINE_LEN (LINE_LEN(DRM_MAX_CRC_NR))
250
crtc_crc_read(struct file * filep,char __user * user_buf,size_t count,loff_t * pos)251 static ssize_t crtc_crc_read(struct file *filep, char __user *user_buf,
252 size_t count, loff_t *pos)
253 {
254 struct drm_crtc *crtc = filep->f_inode->i_private;
255 struct drm_crtc_crc *crc = &crtc->crc;
256 struct drm_crtc_crc_entry *entry;
257 char buf[MAX_LINE_LEN];
258 int ret, i;
259
260 spin_lock_irq(&crc->lock);
261
262 if (!crc->source) {
263 spin_unlock_irq(&crc->lock);
264 return 0;
265 }
266
267 /* Nothing to read? */
268 while (crtc_crc_data_count(crc) == 0) {
269 if (filep->f_flags & O_NONBLOCK) {
270 spin_unlock_irq(&crc->lock);
271 return -EAGAIN;
272 }
273
274 ret = wait_event_interruptible_lock_irq(crc->wq,
275 crtc_crc_data_count(crc),
276 crc->lock);
277 if (ret) {
278 spin_unlock_irq(&crc->lock);
279 return ret;
280 }
281 }
282
283 /* We know we have an entry to be read */
284 entry = &crc->entries[crc->tail];
285
286 if (count < LINE_LEN(crc->values_cnt)) {
287 spin_unlock_irq(&crc->lock);
288 return -EINVAL;
289 }
290
291 BUILD_BUG_ON_NOT_POWER_OF_2(DRM_CRC_ENTRIES_NR);
292 crc->tail = (crc->tail + 1) & (DRM_CRC_ENTRIES_NR - 1);
293
294 spin_unlock_irq(&crc->lock);
295
296 if (entry->has_frame_counter)
297 sprintf(buf, "0x%08x", entry->frame);
298 else
299 sprintf(buf, "XXXXXXXXXX");
300
301 for (i = 0; i < crc->values_cnt; i++)
302 sprintf(buf + 10 + i * 11, " 0x%08x", entry->crcs[i]);
303 sprintf(buf + 10 + crc->values_cnt * 11, "\n");
304
305 if (copy_to_user(user_buf, buf, LINE_LEN(crc->values_cnt)))
306 return -EFAULT;
307
308 return LINE_LEN(crc->values_cnt);
309 }
310
311 static const struct file_operations drm_crtc_crc_data_fops = {
312 .owner = THIS_MODULE,
313 .open = crtc_crc_open,
314 .read = crtc_crc_read,
315 .release = crtc_crc_release,
316 };
317
drm_debugfs_crtc_crc_add(struct drm_crtc * crtc)318 int drm_debugfs_crtc_crc_add(struct drm_crtc *crtc)
319 {
320 struct dentry *crc_ent, *ent;
321
322 if (!crtc->funcs->set_crc_source)
323 return 0;
324
325 crc_ent = debugfs_create_dir("crc", crtc->debugfs_entry);
326 if (!crc_ent)
327 return -ENOMEM;
328
329 ent = debugfs_create_file("control", S_IRUGO, crc_ent, crtc,
330 &drm_crtc_crc_control_fops);
331 if (!ent)
332 goto error;
333
334 ent = debugfs_create_file("data", S_IRUGO, crc_ent, crtc,
335 &drm_crtc_crc_data_fops);
336 if (!ent)
337 goto error;
338
339 return 0;
340
341 error:
342 debugfs_remove_recursive(crc_ent);
343
344 return -ENOMEM;
345 }
346
347 /**
348 * drm_crtc_add_crc_entry - Add entry with CRC information for a frame
349 * @crtc: CRTC to which the frame belongs
350 * @has_frame: whether this entry has a frame number to go with
351 * @frame: number of the frame these CRCs are about
352 * @crcs: array of CRC values, with length matching #drm_crtc_crc.values_cnt
353 *
354 * For each frame, the driver polls the source of CRCs for new data and calls
355 * this function to add them to the buffer from where userspace reads.
356 */
drm_crtc_add_crc_entry(struct drm_crtc * crtc,bool has_frame,uint32_t frame,uint32_t * crcs)357 int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
358 uint32_t frame, uint32_t *crcs)
359 {
360 struct drm_crtc_crc *crc = &crtc->crc;
361 struct drm_crtc_crc_entry *entry;
362 int head, tail;
363 unsigned long flags;
364
365 spin_lock_irqsave(&crc->lock, flags);
366
367 /* Caller may not have noticed yet that userspace has stopped reading */
368 if (!crc->entries) {
369 spin_unlock_irqrestore(&crc->lock, flags);
370 return -EINVAL;
371 }
372
373 head = crc->head;
374 tail = crc->tail;
375
376 if (CIRC_SPACE(head, tail, DRM_CRC_ENTRIES_NR) < 1) {
377 bool was_overflow = crc->overflow;
378
379 crc->overflow = true;
380 spin_unlock_irqrestore(&crc->lock, flags);
381
382 if (!was_overflow)
383 DRM_ERROR("Overflow of CRC buffer, userspace reads too slow.\n");
384
385 return -ENOBUFS;
386 }
387
388 entry = &crc->entries[head];
389 entry->frame = frame;
390 entry->has_frame_counter = has_frame;
391 memcpy(&entry->crcs, crcs, sizeof(*crcs) * crc->values_cnt);
392
393 head = (head + 1) & (DRM_CRC_ENTRIES_NR - 1);
394 crc->head = head;
395
396 spin_unlock_irqrestore(&crc->lock, flags);
397
398 wake_up_interruptible(&crc->wq);
399
400 return 0;
401 }
402 EXPORT_SYMBOL_GPL(drm_crtc_add_crc_entry);
403