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->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 const struct file_operations drm_crtc_crc_data_fops = {
 311         .owner = THIS_MODULE,
 312         .open = crtc_crc_open,
 313         .read = crtc_crc_read,
 314         .release = crtc_crc_release,
 315 };
 316
 317 int drm_debugfs_crtc_crc_add(struct drm_crtc *crtc)
 318 {
 319         struct dentry *crc_ent, *ent;
 320
 321         if (!crtc->funcs->set_crc_source)
 322                 return 0;
 323
 324         crc_ent = debugfs_create_dir("crc", crtc->debugfs_entry);
 325         if (!crc_ent)
 326                 return -ENOMEM;
 327
 328         ent = debugfs_create_file("control", S_IRUGO, crc_ent, crtc,
 329                                   &drm_crtc_crc_control_fops);
 330         if (!ent)
 331                 goto error;
 332
 333         ent = debugfs_create_file("data", S_IRUGO, crc_ent, crtc,
 334                                   &drm_crtc_crc_data_fops);
 335         if (!ent)
 336                 goto error;
 337
 338         return 0;
 339
 340 error:
 341         debugfs_remove_recursive(crc_ent);
 342
 343         return -ENOMEM;
 344 }
 345
 346 /**
 347  * drm_crtc_add_crc_entry - Add entry with CRC information for a frame
 348  * @crtc: CRTC to which the frame belongs
 349  * @has_frame: whether this entry has a frame number to go with
 350  * @frame: number of the frame these CRCs are about
 351  * @crcs: array of CRC values, with length matching #drm_crtc_crc.values_cnt
 352  *
 353  * For each frame, the driver polls the source of CRCs for new data and calls
 354  * this function to add them to the buffer from where userspace reads.
 355  */
 356 int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
 357                            uint32_t frame, uint32_t *crcs)
 358 {
 359         struct drm_crtc_crc *crc = &crtc->crc;
 360         struct drm_crtc_crc_entry *entry;
 361         int head, tail;
 362
 363         spin_lock(&crc->lock);
 364
 365         /* Caller may not have noticed yet that userspace has stopped reading */
 366         if (!crc->entries) {
 367                 spin_unlock(&crc->lock);
 368                 return -EINVAL;
 369         }
 370
 371         head = crc->head;
 372         tail = crc->tail;
 373
 374         if (CIRC_SPACE(head, tail, DRM_CRC_ENTRIES_NR) < 1) {
 375                 spin_unlock(&crc->lock);
 376                 DRM_ERROR("Overflow of CRC buffer, userspace reads too slow.\n");
 377                 return -ENOBUFS;
 378         }
 379
 380         entry = &crc->entries[head];
 381         entry->frame = frame;
 382         entry->has_frame_counter = has_frame;
 383         memcpy(&entry->crcs, crcs, sizeof(*crcs) * crc->values_cnt);
 384
 385         head = (head + 1) & (DRM_CRC_ENTRIES_NR - 1);
 386         crc->head = head;
 387
 388         spin_unlock(&crc->lock);
 389
 390         wake_up_interruptible(&crc->wq);
 391
 392         return 0;
 393 }
 394 EXPORT_SYMBOL_GPL(drm_crtc_add_crc_entry);