drivers/gpu/drm/drm_debugfs_crc.c

   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->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
 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_single_interruptible(&crtc->mutex);
 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
 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
 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
 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  */
 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);