linux/drivers/gpu/drm/drm_debugfs_crc.c
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   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 index of the CRTC.
  50 * Accepted values are source names (which are driver-specific) and the "auto"
  51 * keyword, which will let the driver select a default source of frame CRCs
  52 * 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
  83static 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
 108out:
 109        seq_printf(m, "%s*\n", crtc->crc.source);
 110        return 0;
 111}
 112
 113static 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
 120static 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] == '\n')
 144                source[len] = '\0';
 145
 146        ret = crtc->funcs->verify_crc_source(crtc, source, &values_cnt);
 147        if (ret)
 148                return ret;
 149
 150        spin_lock_irq(&crc->lock);
 151
 152        if (crc->opened) {
 153                spin_unlock_irq(&crc->lock);
 154                kfree(source);
 155                return -EBUSY;
 156        }
 157
 158        kfree(crc->source);
 159        crc->source = source;
 160
 161        spin_unlock_irq(&crc->lock);
 162
 163        *offp += len;
 164        return len;
 165}
 166
 167static const struct file_operations drm_crtc_crc_control_fops = {
 168        .owner = THIS_MODULE,
 169        .open = crc_control_open,
 170        .read = seq_read,
 171        .llseek = seq_lseek,
 172        .release = single_release,
 173        .write = crc_control_write
 174};
 175
 176static int crtc_crc_data_count(struct drm_crtc_crc *crc)
 177{
 178        assert_spin_locked(&crc->lock);
 179        return CIRC_CNT(crc->head, crc->tail, DRM_CRC_ENTRIES_NR);
 180}
 181
 182static void crtc_crc_cleanup(struct drm_crtc_crc *crc)
 183{
 184        kfree(crc->entries);
 185        crc->overflow = false;
 186        crc->entries = NULL;
 187        crc->head = 0;
 188        crc->tail = 0;
 189        crc->values_cnt = 0;
 190        crc->opened = false;
 191}
 192
 193static int crtc_crc_open(struct inode *inode, struct file *filep)
 194{
 195        struct drm_crtc *crtc = inode->i_private;
 196        struct drm_crtc_crc *crc = &crtc->crc;
 197        struct drm_crtc_crc_entry *entries = NULL;
 198        size_t values_cnt;
 199        int ret = 0;
 200
 201        if (drm_drv_uses_atomic_modeset(crtc->dev)) {
 202                ret = drm_modeset_lock_single_interruptible(&crtc->mutex);
 203                if (ret)
 204                        return ret;
 205
 206                if (!crtc->state->active)
 207                        ret = -EIO;
 208                drm_modeset_unlock(&crtc->mutex);
 209
 210                if (ret)
 211                        return ret;
 212        }
 213
 214        ret = crtc->funcs->verify_crc_source(crtc, crc->source, &values_cnt);
 215        if (ret)
 216                return ret;
 217
 218        if (WARN_ON(values_cnt > DRM_MAX_CRC_NR))
 219                return -EINVAL;
 220
 221        if (WARN_ON(values_cnt == 0))
 222                return -EINVAL;
 223
 224        entries = kcalloc(DRM_CRC_ENTRIES_NR, sizeof(*entries), GFP_KERNEL);
 225        if (!entries)
 226                return -ENOMEM;
 227
 228        spin_lock_irq(&crc->lock);
 229        if (!crc->opened) {
 230                crc->opened = true;
 231                crc->entries = entries;
 232                crc->values_cnt = values_cnt;
 233        } else {
 234                ret = -EBUSY;
 235        }
 236        spin_unlock_irq(&crc->lock);
 237
 238        if (ret) {
 239                kfree(entries);
 240                return ret;
 241        }
 242
 243        ret = crtc->funcs->set_crc_source(crtc, crc->source);
 244        if (ret)
 245                goto err;
 246
 247        return 0;
 248
 249err:
 250        spin_lock_irq(&crc->lock);
 251        crtc_crc_cleanup(crc);
 252        spin_unlock_irq(&crc->lock);
 253        return ret;
 254}
 255
 256static int crtc_crc_release(struct inode *inode, struct file *filep)
 257{
 258        struct drm_crtc *crtc = filep->f_inode->i_private;
 259        struct drm_crtc_crc *crc = &crtc->crc;
 260
 261        crtc->funcs->set_crc_source(crtc, NULL);
 262
 263        spin_lock_irq(&crc->lock);
 264        crtc_crc_cleanup(crc);
 265        spin_unlock_irq(&crc->lock);
 266
 267        return 0;
 268}
 269
 270/*
 271 * 1 frame field of 10 chars plus a number of CRC fields of 10 chars each, space
 272 * separated, with a newline at the end and null-terminated.
 273 */
 274#define LINE_LEN(values_cnt)    (10 + 11 * values_cnt + 1 + 1)
 275#define MAX_LINE_LEN            (LINE_LEN(DRM_MAX_CRC_NR))
 276
 277static ssize_t crtc_crc_read(struct file *filep, char __user *user_buf,
 278                             size_t count, loff_t *pos)
 279{
 280        struct drm_crtc *crtc = filep->f_inode->i_private;
 281        struct drm_crtc_crc *crc = &crtc->crc;
 282        struct drm_crtc_crc_entry *entry;
 283        char buf[MAX_LINE_LEN];
 284        int ret, i;
 285
 286        spin_lock_irq(&crc->lock);
 287
 288        if (!crc->source) {
 289                spin_unlock_irq(&crc->lock);
 290                return 0;
 291        }
 292
 293        /* Nothing to read? */
 294        while (crtc_crc_data_count(crc) == 0) {
 295                if (filep->f_flags & O_NONBLOCK) {
 296                        spin_unlock_irq(&crc->lock);
 297                        return -EAGAIN;
 298                }
 299
 300                ret = wait_event_interruptible_lock_irq(crc->wq,
 301                                                        crtc_crc_data_count(crc),
 302                                                        crc->lock);
 303                if (ret) {
 304                        spin_unlock_irq(&crc->lock);
 305                        return ret;
 306                }
 307        }
 308
 309        /* We know we have an entry to be read */
 310        entry = &crc->entries[crc->tail];
 311
 312        if (count < LINE_LEN(crc->values_cnt)) {
 313                spin_unlock_irq(&crc->lock);
 314                return -EINVAL;
 315        }
 316
 317        BUILD_BUG_ON_NOT_POWER_OF_2(DRM_CRC_ENTRIES_NR);
 318        crc->tail = (crc->tail + 1) & (DRM_CRC_ENTRIES_NR - 1);
 319
 320        spin_unlock_irq(&crc->lock);
 321
 322        if (entry->has_frame_counter)
 323                sprintf(buf, "0x%08x", entry->frame);
 324        else
 325                sprintf(buf, "XXXXXXXXXX");
 326
 327        for (i = 0; i < crc->values_cnt; i++)
 328                sprintf(buf + 10 + i * 11, " 0x%08x", entry->crcs[i]);
 329        sprintf(buf + 10 + crc->values_cnt * 11, "\n");
 330
 331        if (copy_to_user(user_buf, buf, LINE_LEN(crc->values_cnt)))
 332                return -EFAULT;
 333
 334        return LINE_LEN(crc->values_cnt);
 335}
 336
 337static unsigned int crtc_crc_poll(struct file *file, poll_table *wait)
 338{
 339        struct drm_crtc *crtc = file->f_inode->i_private;
 340        struct drm_crtc_crc *crc = &crtc->crc;
 341        unsigned ret;
 342
 343        poll_wait(file, &crc->wq, wait);
 344
 345        spin_lock_irq(&crc->lock);
 346        if (crc->source && crtc_crc_data_count(crc))
 347                ret = POLLIN | POLLRDNORM;
 348        else
 349                ret = 0;
 350        spin_unlock_irq(&crc->lock);
 351
 352        return ret;
 353}
 354
 355static const struct file_operations drm_crtc_crc_data_fops = {
 356        .owner = THIS_MODULE,
 357        .open = crtc_crc_open,
 358        .read = crtc_crc_read,
 359        .poll = crtc_crc_poll,
 360        .release = crtc_crc_release,
 361};
 362
 363void drm_debugfs_crtc_crc_add(struct drm_crtc *crtc)
 364{
 365        struct dentry *crc_ent;
 366
 367        if (!crtc->funcs->set_crc_source || !crtc->funcs->verify_crc_source)
 368                return;
 369
 370        crc_ent = debugfs_create_dir("crc", crtc->debugfs_entry);
 371
 372        debugfs_create_file("control", S_IRUGO, crc_ent, crtc,
 373                            &drm_crtc_crc_control_fops);
 374        debugfs_create_file("data", S_IRUGO, crc_ent, crtc,
 375                            &drm_crtc_crc_data_fops);
 376}
 377
 378/**
 379 * drm_crtc_add_crc_entry - Add entry with CRC information for a frame
 380 * @crtc: CRTC to which the frame belongs
 381 * @has_frame: whether this entry has a frame number to go with
 382 * @frame: number of the frame these CRCs are about
 383 * @crcs: array of CRC values, with length matching #drm_crtc_crc.values_cnt
 384 *
 385 * For each frame, the driver polls the source of CRCs for new data and calls
 386 * this function to add them to the buffer from where userspace reads.
 387 */
 388int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
 389                           uint32_t frame, uint32_t *crcs)
 390{
 391        struct drm_crtc_crc *crc = &crtc->crc;
 392        struct drm_crtc_crc_entry *entry;
 393        int head, tail;
 394        unsigned long flags;
 395
 396        spin_lock_irqsave(&crc->lock, flags);
 397
 398        /* Caller may not have noticed yet that userspace has stopped reading */
 399        if (!crc->entries) {
 400                spin_unlock_irqrestore(&crc->lock, flags);
 401                return -EINVAL;
 402        }
 403
 404        head = crc->head;
 405        tail = crc->tail;
 406
 407        if (CIRC_SPACE(head, tail, DRM_CRC_ENTRIES_NR) < 1) {
 408                bool was_overflow = crc->overflow;
 409
 410                crc->overflow = true;
 411                spin_unlock_irqrestore(&crc->lock, flags);
 412
 413                if (!was_overflow)
 414                        DRM_ERROR("Overflow of CRC buffer, userspace reads too slow.\n");
 415
 416                return -ENOBUFS;
 417        }
 418
 419        entry = &crc->entries[head];
 420        entry->frame = frame;
 421        entry->has_frame_counter = has_frame;
 422        memcpy(&entry->crcs, crcs, sizeof(*crcs) * crc->values_cnt);
 423
 424        head = (head + 1) & (DRM_CRC_ENTRIES_NR - 1);
 425        crc->head = head;
 426
 427        spin_unlock_irqrestore(&crc->lock, flags);
 428
 429        wake_up_interruptible(&crc->wq);
 430
 431        return 0;
 432}
 433EXPORT_SYMBOL_GPL(drm_crtc_add_crc_entry);
 434