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 <linux/export.h>
33#include <linux/poll.h>
34#include <linux/uaccess.h>
35
36#include <drm/drm_crtc.h>
37#include <drm/drm_debugfs_crc.h>
38#include <drm/drm_drv.h>
39#include <drm/drm_print.h>
40
41#include "drm_internal.h"
42
43/**
44 * DOC: CRC ABI
45 *
46 * DRM device drivers can provide to userspace CRC information of each frame as
47 * it reached a given hardware component (a CRC sampling "source").
48 *
49 * Userspace can control generation of CRCs in a given CRTC by writing to the
50 * file dri/0/crtc-N/crc/control in debugfs, with N being the :ref:`index of
51 * the CRTC<crtc_index>`. Accepted values are source names (which are
52 * driver-specific) and the "auto" keyword, which will let the driver select a
53 * default source of frame CRCs for this CRTC.
54 *
55 * Once frame CRC generation is enabled, userspace can capture them by reading
56 * the dri/0/crtc-N/crc/data file. Each line in that file contains the frame
57 * number in the first field and then a number of unsigned integer fields
58 * containing the CRC data. Fields are separated by a single space and the number
59 * of CRC fields is source-specific.
60 *
61 * Note that though in some cases the CRC is computed in a specified way and on
62 * the frame contents as supplied by userspace (eDP 1.3), in general the CRC
63 * computation is performed in an unspecified way and on frame contents that have
64 * been already processed in also an unspecified way and thus userspace cannot
65 * rely on being able to generate matching CRC values for the frame contents that
66 * it submits. In this general case, the maximum userspace can do is to compare
67 * the reported CRCs of frames that should have the same contents.
68 *
69 * On the driver side the implementation effort is minimal, drivers only need to
70 * implement &drm_crtc_funcs.set_crc_source and &drm_crtc_funcs.verify_crc_source.
71 * The debugfs files are automatically set up if those vfuncs are set. CRC samples
72 * need to be captured in the driver by calling drm_crtc_add_crc_entry().
73 * Depending on the driver and HW requirements, &drm_crtc_funcs.set_crc_source
74 * may result in a commit (even a full modeset).
75 *
76 * CRC results must be reliable across non-full-modeset atomic commits, so if a
77 * commit via DRM_IOCTL_MODE_ATOMIC would disable or otherwise interfere with
78 * CRC generation, then the driver must mark that commit as a full modeset
79 * (drm_atomic_crtc_needs_modeset() should return true). As a result, to ensure
80 * consistent results, generic userspace must re-setup CRC generation after a
81 * legacy SETCRTC or an atomic commit with DRM_MODE_ATOMIC_ALLOW_MODESET.
82 */
83
84static int crc_control_show(struct seq_file *m, void *data)
85{
86 struct drm_crtc *crtc = m->private;
87
88 if (crtc->funcs->get_crc_sources) {
89 size_t count;
90 const char *const *sources = crtc->funcs->get_crc_sources(crtc,
91 &count);
92 size_t values_cnt;
93 int i;
94
95 if (count == 0 || !sources)
96 goto out;
97
98 for (i = 0; i < count; i++)
99 if (!crtc->funcs->verify_crc_source(crtc, sources[i],
100 &values_cnt)) {
101 if (strcmp(sources[i], crtc->crc.source))
102 seq_printf(m, fmt: "%s\n", sources[i]);
103 else
104 seq_printf(m, fmt: "%s*\n", sources[i]);
105 }
106 }
107 return 0;
108
109out:
110 seq_printf(m, fmt: "%s*\n", crtc->crc.source);
111 return 0;
112}
113
114static int crc_control_open(struct inode *inode, struct file *file)
115{
116 struct drm_crtc *crtc = inode->i_private;
117
118 return single_open(file, crc_control_show, crtc);
119}
120
121static ssize_t crc_control_write(struct file *file, const char __user *ubuf,
122 size_t len, loff_t *offp)
123{
124 struct seq_file *m = file->private_data;
125 struct drm_crtc *crtc = m->private;
126 struct drm_crtc_crc *crc = &crtc->crc;
127 char *source;
128 size_t values_cnt;
129 int ret;
130
131 if (len == 0)
132 return 0;
133
134 if (len > PAGE_SIZE - 1) {
135 DRM_DEBUG_KMS("Expected < %lu bytes into crtc crc control\n",
136 PAGE_SIZE);
137 return -E2BIG;
138 }
139
140 source = memdup_user_nul(ubuf, len);
141 if (IS_ERR(ptr: source))
142 return PTR_ERR(ptr: source);
143
144 if (source[len - 1] == '\n')
145 source[len - 1] = '\0';
146
147 ret = crtc->funcs->verify_crc_source(crtc, source, &values_cnt);
148 if (ret) {
149 kfree(objp: source);
150 return ret;
151 }
152
153 spin_lock_irq(lock: &crc->lock);
154
155 if (crc->opened) {
156 spin_unlock_irq(lock: &crc->lock);
157 kfree(objp: source);
158 return -EBUSY;
159 }
160
161 kfree(objp: crc->source);
162 crc->source = source;
163
164 spin_unlock_irq(lock: &crc->lock);
165
166 *offp += len;
167 return len;
168}
169
170static const struct file_operations drm_crtc_crc_control_fops = {
171 .owner = THIS_MODULE,
172 .open = crc_control_open,
173 .read = seq_read,
174 .llseek = seq_lseek,
175 .release = single_release,
176 .write = crc_control_write
177};
178
179static int crtc_crc_data_count(struct drm_crtc_crc *crc)
180{
181 assert_spin_locked(&crc->lock);
182 return CIRC_CNT(crc->head, crc->tail, DRM_CRC_ENTRIES_NR);
183}
184
185static void crtc_crc_cleanup(struct drm_crtc_crc *crc)
186{
187 kfree(objp: crc->entries);
188 crc->overflow = false;
189 crc->entries = NULL;
190 crc->head = 0;
191 crc->tail = 0;
192 crc->values_cnt = 0;
193 crc->opened = false;
194}
195
196static int crtc_crc_open(struct inode *inode, struct file *filep)
197{
198 struct drm_crtc *crtc = inode->i_private;
199 struct drm_crtc_crc *crc = &crtc->crc;
200 struct drm_crtc_crc_entry *entries = NULL;
201 size_t values_cnt;
202 int ret = 0;
203
204 if (drm_drv_uses_atomic_modeset(dev: crtc->dev)) {
205 ret = drm_modeset_lock_single_interruptible(lock: &crtc->mutex);
206 if (ret)
207 return ret;
208
209 if (!crtc->state->active)
210 ret = -EIO;
211 drm_modeset_unlock(lock: &crtc->mutex);
212
213 if (ret)
214 return ret;
215 }
216
217 ret = crtc->funcs->verify_crc_source(crtc, crc->source, &values_cnt);
218 if (ret)
219 return ret;
220
221 if (WARN_ON(values_cnt > DRM_MAX_CRC_NR))
222 return -EINVAL;
223
224 if (WARN_ON(values_cnt == 0))
225 return -EINVAL;
226
227 entries = kcalloc(DRM_CRC_ENTRIES_NR, sizeof(*entries), GFP_KERNEL);
228 if (!entries)
229 return -ENOMEM;
230
231 spin_lock_irq(lock: &crc->lock);
232 if (!crc->opened) {
233 crc->opened = true;
234 crc->entries = entries;
235 crc->values_cnt = values_cnt;
236 } else {
237 ret = -EBUSY;
238 }
239 spin_unlock_irq(lock: &crc->lock);
240
241 if (ret) {
242 kfree(objp: entries);
243 return ret;
244 }
245
246 ret = crtc->funcs->set_crc_source(crtc, crc->source);
247 if (ret)
248 goto err;
249
250 return 0;
251
252err:
253 spin_lock_irq(lock: &crc->lock);
254 crtc_crc_cleanup(crc);
255 spin_unlock_irq(lock: &crc->lock);
256 return ret;
257}
258
259static int crtc_crc_release(struct inode *inode, struct file *filep)
260{
261 struct drm_crtc *crtc = filep->f_inode->i_private;
262 struct drm_crtc_crc *crc = &crtc->crc;
263
264 /* terminate the infinite while loop if 'drm_dp_aux_crc_work' running */
265 spin_lock_irq(lock: &crc->lock);
266 crc->opened = false;
267 spin_unlock_irq(lock: &crc->lock);
268
269 crtc->funcs->set_crc_source(crtc, NULL);
270
271 spin_lock_irq(lock: &crc->lock);
272 crtc_crc_cleanup(crc);
273 spin_unlock_irq(lock: &crc->lock);
274
275 return 0;
276}
277
278/*
279 * 1 frame field of 10 chars plus a number of CRC fields of 10 chars each, space
280 * separated, with a newline at the end and null-terminated.
281 */
282#define LINE_LEN(values_cnt) (10 + 11 * values_cnt + 1 + 1)
283#define MAX_LINE_LEN (LINE_LEN(DRM_MAX_CRC_NR))
284
285static ssize_t crtc_crc_read(struct file *filep, char __user *user_buf,
286 size_t count, loff_t *pos)
287{
288 struct drm_crtc *crtc = filep->f_inode->i_private;
289 struct drm_crtc_crc *crc = &crtc->crc;
290 struct drm_crtc_crc_entry *entry;
291 char buf[MAX_LINE_LEN];
292 int ret, i;
293
294 spin_lock_irq(lock: &crc->lock);
295
296 if (!crc->source) {
297 spin_unlock_irq(lock: &crc->lock);
298 return 0;
299 }
300
301 /* Nothing to read? */
302 while (crtc_crc_data_count(crc) == 0) {
303 if (filep->f_flags & O_NONBLOCK) {
304 spin_unlock_irq(lock: &crc->lock);
305 return -EAGAIN;
306 }
307
308 ret = wait_event_interruptible_lock_irq(crc->wq,
309 crtc_crc_data_count(crc),
310 crc->lock);
311 if (ret) {
312 spin_unlock_irq(lock: &crc->lock);
313 return ret;
314 }
315 }
316
317 /* We know we have an entry to be read */
318 entry = &crc->entries[crc->tail];
319
320 if (count < LINE_LEN(crc->values_cnt)) {
321 spin_unlock_irq(lock: &crc->lock);
322 return -EINVAL;
323 }
324
325 BUILD_BUG_ON_NOT_POWER_OF_2(DRM_CRC_ENTRIES_NR);
326 crc->tail = (crc->tail + 1) & (DRM_CRC_ENTRIES_NR - 1);
327
328 spin_unlock_irq(lock: &crc->lock);
329
330 if (entry->has_frame_counter)
331 sprintf(buf, fmt: "0x%08x", entry->frame);
332 else
333 sprintf(buf, fmt: "XXXXXXXXXX");
334
335 for (i = 0; i < crc->values_cnt; i++)
336 sprintf(buf: buf + 10 + i * 11, fmt: " 0x%08x", entry->crcs[i]);
337 sprintf(buf: buf + 10 + crc->values_cnt * 11, fmt: "\n");
338
339 if (copy_to_user(to: user_buf, from: buf, LINE_LEN(crc->values_cnt)))
340 return -EFAULT;
341
342 return LINE_LEN(crc->values_cnt);
343}
344
345static __poll_t crtc_crc_poll(struct file *file, poll_table *wait)
346{
347 struct drm_crtc *crtc = file->f_inode->i_private;
348 struct drm_crtc_crc *crc = &crtc->crc;
349 __poll_t ret = 0;
350
351 poll_wait(filp: file, wait_address: &crc->wq, p: wait);
352
353 spin_lock_irq(lock: &crc->lock);
354 if (crc->source && crtc_crc_data_count(crc))
355 ret |= EPOLLIN | EPOLLRDNORM;
356 spin_unlock_irq(lock: &crc->lock);
357
358 return ret;
359}
360
361static const struct file_operations drm_crtc_crc_data_fops = {
362 .owner = THIS_MODULE,
363 .open = crtc_crc_open,
364 .read = crtc_crc_read,
365 .poll = crtc_crc_poll,
366 .release = crtc_crc_release,
367};
368
369void drm_debugfs_crtc_crc_add(struct drm_crtc *crtc)
370{
371 struct dentry *crc_ent;
372
373 if (!crtc->funcs->set_crc_source || !crtc->funcs->verify_crc_source)
374 return;
375
376 crc_ent = debugfs_create_dir(name: "crc", parent: crtc->debugfs_entry);
377
378 debugfs_create_file("control", S_IRUGO | S_IWUSR, crc_ent, crtc,
379 &drm_crtc_crc_control_fops);
380 debugfs_create_file("data", S_IRUGO, crc_ent, crtc,
381 &drm_crtc_crc_data_fops);
382}
383
384/**
385 * drm_crtc_add_crc_entry - Add entry with CRC information for a frame
386 * @crtc: CRTC to which the frame belongs
387 * @has_frame: whether this entry has a frame number to go with
388 * @frame: number of the frame these CRCs are about
389 * @crcs: array of CRC values, with length matching #drm_crtc_crc.values_cnt
390 *
391 * For each frame, the driver polls the source of CRCs for new data and calls
392 * this function to add them to the buffer from where userspace reads.
393 */
394int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
395 uint32_t frame, uint32_t *crcs)
396{
397 struct drm_crtc_crc *crc = &crtc->crc;
398 struct drm_crtc_crc_entry *entry;
399 int head, tail;
400 unsigned long flags;
401
402 spin_lock_irqsave(&crc->lock, flags);
403
404 /* Caller may not have noticed yet that userspace has stopped reading */
405 if (!crc->entries) {
406 spin_unlock_irqrestore(lock: &crc->lock, flags);
407 return -EINVAL;
408 }
409
410 head = crc->head;
411 tail = crc->tail;
412
413 if (CIRC_SPACE(head, tail, DRM_CRC_ENTRIES_NR) < 1) {
414 bool was_overflow = crc->overflow;
415
416 crc->overflow = true;
417 spin_unlock_irqrestore(lock: &crc->lock, flags);
418
419 if (!was_overflow)
420 DRM_ERROR("Overflow of CRC buffer, userspace reads too slow.\n");
421
422 return -ENOBUFS;
423 }
424
425 entry = &crc->entries[head];
426 entry->frame = frame;
427 entry->has_frame_counter = has_frame;
428 memcpy(&entry->crcs, crcs, sizeof(*crcs) * crc->values_cnt);
429
430 head = (head + 1) & (DRM_CRC_ENTRIES_NR - 1);
431 crc->head = head;
432
433 spin_unlock_irqrestore(lock: &crc->lock, flags);
434
435 wake_up_interruptible(&crc->wq);
436
437 return 0;
438}
439EXPORT_SYMBOL_GPL(drm_crtc_add_crc_entry);
440

source code of linux/drivers/gpu/drm/drm_debugfs_crc.c