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