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