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 
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 
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 
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] == '\n')
105 		source[len] = '\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 
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 
139 static void crtc_crc_cleanup(struct drm_crtc_crc *crc)
140 {
141 	kfree(crc->entries);
142 	crc->entries = NULL;
143 	crc->head = 0;
144 	crc->tail = 0;
145 	crc->values_cnt = 0;
146 	crc->opened = false;
147 }
148 
149 static int crtc_crc_open(struct inode *inode, struct file *filep)
150 {
151 	struct drm_crtc *crtc = inode->i_private;
152 	struct drm_crtc_crc *crc = &crtc->crc;
153 	struct drm_crtc_crc_entry *entries = NULL;
154 	size_t values_cnt;
155 	int ret = 0;
156 
157 	if (drm_drv_uses_atomic_modeset(crtc->dev)) {
158 		ret = drm_modeset_lock_single_interruptible(&crtc->mutex);
159 		if (ret)
160 			return ret;
161 
162 		if (!crtc->state->active)
163 			ret = -EIO;
164 		drm_modeset_unlock(&crtc->mutex);
165 
166 		if (ret)
167 			return ret;
168 	}
169 
170 	spin_lock_irq(&crc->lock);
171 	if (!crc->opened)
172 		crc->opened = true;
173 	else
174 		ret = -EBUSY;
175 	spin_unlock_irq(&crc->lock);
176 
177 	if (ret)
178 		return ret;
179 
180 	ret = crtc->funcs->set_crc_source(crtc, crc->source, &values_cnt);
181 	if (ret)
182 		goto err;
183 
184 	if (WARN_ON(values_cnt > DRM_MAX_CRC_NR)) {
185 		ret = -EINVAL;
186 		goto err_disable;
187 	}
188 
189 	if (WARN_ON(values_cnt == 0)) {
190 		ret = -EINVAL;
191 		goto err_disable;
192 	}
193 
194 	entries = kcalloc(DRM_CRC_ENTRIES_NR, sizeof(*entries), GFP_KERNEL);
195 	if (!entries) {
196 		ret = -ENOMEM;
197 		goto err_disable;
198 	}
199 
200 	spin_lock_irq(&crc->lock);
201 	crc->entries = entries;
202 	crc->values_cnt = values_cnt;
203 
204 	/*
205 	 * Only return once we got a first frame, so userspace doesn't have to
206 	 * guess when this particular piece of HW will be ready to start
207 	 * generating CRCs.
208 	 */
209 	ret = wait_event_interruptible_lock_irq(crc->wq,
210 						crtc_crc_data_count(crc),
211 						crc->lock);
212 	spin_unlock_irq(&crc->lock);
213 
214 	if (ret)
215 		goto err_disable;
216 
217 	return 0;
218 
219 err_disable:
220 	crtc->funcs->set_crc_source(crtc, NULL, &values_cnt);
221 err:
222 	spin_lock_irq(&crc->lock);
223 	crtc_crc_cleanup(crc);
224 	spin_unlock_irq(&crc->lock);
225 	return ret;
226 }
227 
228 static int crtc_crc_release(struct inode *inode, struct file *filep)
229 {
230 	struct drm_crtc *crtc = filep->f_inode->i_private;
231 	struct drm_crtc_crc *crc = &crtc->crc;
232 	size_t values_cnt;
233 
234 	crtc->funcs->set_crc_source(crtc, NULL, &values_cnt);
235 
236 	spin_lock_irq(&crc->lock);
237 	crtc_crc_cleanup(crc);
238 	spin_unlock_irq(&crc->lock);
239 
240 	return 0;
241 }
242 
243 /*
244  * 1 frame field of 10 chars plus a number of CRC fields of 10 chars each, space
245  * separated, with a newline at the end and null-terminated.
246  */
247 #define LINE_LEN(values_cnt)	(10 + 11 * values_cnt + 1 + 1)
248 #define MAX_LINE_LEN		(LINE_LEN(DRM_MAX_CRC_NR))
249 
250 static ssize_t crtc_crc_read(struct file *filep, char __user *user_buf,
251 			     size_t count, loff_t *pos)
252 {
253 	struct drm_crtc *crtc = filep->f_inode->i_private;
254 	struct drm_crtc_crc *crc = &crtc->crc;
255 	struct drm_crtc_crc_entry *entry;
256 	char buf[MAX_LINE_LEN];
257 	int ret, i;
258 
259 	spin_lock_irq(&crc->lock);
260 
261 	if (!crc->source) {
262 		spin_unlock_irq(&crc->lock);
263 		return 0;
264 	}
265 
266 	/* Nothing to read? */
267 	while (crtc_crc_data_count(crc) == 0) {
268 		if (filep->f_flags & O_NONBLOCK) {
269 			spin_unlock_irq(&crc->lock);
270 			return -EAGAIN;
271 		}
272 
273 		ret = wait_event_interruptible_lock_irq(crc->wq,
274 							crtc_crc_data_count(crc),
275 							crc->lock);
276 		if (ret) {
277 			spin_unlock_irq(&crc->lock);
278 			return ret;
279 		}
280 	}
281 
282 	/* We know we have an entry to be read */
283 	entry = &crc->entries[crc->tail];
284 
285 	if (count < LINE_LEN(crc->values_cnt)) {
286 		spin_unlock_irq(&crc->lock);
287 		return -EINVAL;
288 	}
289 
290 	BUILD_BUG_ON_NOT_POWER_OF_2(DRM_CRC_ENTRIES_NR);
291 	crc->tail = (crc->tail + 1) & (DRM_CRC_ENTRIES_NR - 1);
292 
293 	spin_unlock_irq(&crc->lock);
294 
295 	if (entry->has_frame_counter)
296 		sprintf(buf, "0x%08x", entry->frame);
297 	else
298 		sprintf(buf, "XXXXXXXXXX");
299 
300 	for (i = 0; i < crc->values_cnt; i++)
301 		sprintf(buf + 10 + i * 11, " 0x%08x", entry->crcs[i]);
302 	sprintf(buf + 10 + crc->values_cnt * 11, "\n");
303 
304 	if (copy_to_user(user_buf, buf, LINE_LEN(crc->values_cnt)))
305 		return -EFAULT;
306 
307 	return LINE_LEN(crc->values_cnt);
308 }
309 
310 static unsigned int crtc_crc_poll(struct file *file, poll_table *wait)
311 {
312 	struct drm_crtc *crtc = file->f_inode->i_private;
313 	struct drm_crtc_crc *crc = &crtc->crc;
314 	unsigned ret;
315 
316 	poll_wait(file, &crc->wq, wait);
317 
318 	spin_lock_irq(&crc->lock);
319 	if (crc->source && crtc_crc_data_count(crc))
320 		ret = POLLIN | POLLRDNORM;
321 	else
322 		ret = 0;
323 	spin_unlock_irq(&crc->lock);
324 
325 	return ret;
326 }
327 
328 static const struct file_operations drm_crtc_crc_data_fops = {
329 	.owner = THIS_MODULE,
330 	.open = crtc_crc_open,
331 	.read = crtc_crc_read,
332 	.poll = crtc_crc_poll,
333 	.release = crtc_crc_release,
334 };
335 
336 int drm_debugfs_crtc_crc_add(struct drm_crtc *crtc)
337 {
338 	struct dentry *crc_ent, *ent;
339 
340 	if (!crtc->funcs->set_crc_source)
341 		return 0;
342 
343 	crc_ent = debugfs_create_dir("crc", crtc->debugfs_entry);
344 	if (!crc_ent)
345 		return -ENOMEM;
346 
347 	ent = debugfs_create_file("control", S_IRUGO, crc_ent, crtc,
348 				  &drm_crtc_crc_control_fops);
349 	if (!ent)
350 		goto error;
351 
352 	ent = debugfs_create_file("data", S_IRUGO, crc_ent, crtc,
353 				  &drm_crtc_crc_data_fops);
354 	if (!ent)
355 		goto error;
356 
357 	return 0;
358 
359 error:
360 	debugfs_remove_recursive(crc_ent);
361 
362 	return -ENOMEM;
363 }
364 
365 /**
366  * drm_crtc_add_crc_entry - Add entry with CRC information for a frame
367  * @crtc: CRTC to which the frame belongs
368  * @has_frame: whether this entry has a frame number to go with
369  * @frame: number of the frame these CRCs are about
370  * @crcs: array of CRC values, with length matching #drm_crtc_crc.values_cnt
371  *
372  * For each frame, the driver polls the source of CRCs for new data and calls
373  * this function to add them to the buffer from where userspace reads.
374  */
375 int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
376 			   uint32_t frame, uint32_t *crcs)
377 {
378 	struct drm_crtc_crc *crc = &crtc->crc;
379 	struct drm_crtc_crc_entry *entry;
380 	int head, tail;
381 
382 	spin_lock(&crc->lock);
383 
384 	/* Caller may not have noticed yet that userspace has stopped reading */
385 	if (!crc->entries) {
386 		spin_unlock(&crc->lock);
387 		return -EINVAL;
388 	}
389 
390 	head = crc->head;
391 	tail = crc->tail;
392 
393 	if (CIRC_SPACE(head, tail, DRM_CRC_ENTRIES_NR) < 1) {
394 		spin_unlock(&crc->lock);
395 		DRM_ERROR("Overflow of CRC buffer, userspace reads too slow.\n");
396 		return -ENOBUFS;
397 	}
398 
399 	entry = &crc->entries[head];
400 	entry->frame = frame;
401 	entry->has_frame_counter = has_frame;
402 	memcpy(&entry->crcs, crcs, sizeof(*crcs) * crc->values_cnt);
403 
404 	head = (head + 1) & (DRM_CRC_ENTRIES_NR - 1);
405 	crc->head = head;
406 
407 	spin_unlock(&crc->lock);
408 
409 	wake_up_interruptible(&crc->wq);
410 
411 	return 0;
412 }
413 EXPORT_SYMBOL_GPL(drm_crtc_add_crc_entry);
414