drivers/media/platform/vivid/vivid-sdr-cap.c

   1 /*
   2  * vivid-sdr-cap.c - software defined radio support functions.
   3  *
   4  * Copyright 2014 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
   5  *
   6  * This program is free software; you may redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; version 2 of the License.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  11  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  12  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  13  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  14  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  15  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  16  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  17  * SOFTWARE.
  18  */
  19
  20 #include <linux/errno.h>
  21 #include <linux/kernel.h>
  22 #include <linux/delay.h>
  23 #include <linux/kthread.h>
  24 #include <linux/freezer.h>
  25 #include <linux/math64.h>
  26 #include <linux/videodev2.h>
  27 #include <linux/v4l2-dv-timings.h>
  28 #include <media/v4l2-common.h>
  29 #include <media/v4l2-event.h>
  30 #include <media/v4l2-dv-timings.h>
  31 #include <linux/fixp-arith.h>
  32
  33 #include "vivid-core.h"
  34 #include "vivid-ctrls.h"
  35 #include "vivid-sdr-cap.h"
  36
  37 /* stream formats */
  38 struct vivid_format {
  39         u32     pixelformat;
  40         u32     buffersize;
  41 };
  42
  43 /* format descriptions for capture and preview */
  44 static const struct vivid_format formats[] = {
  45         {
  46                 .pixelformat    = V4L2_SDR_FMT_CU8,
  47                 .buffersize     = SDR_CAP_SAMPLES_PER_BUF * 2,
  48         }, {
  49                 .pixelformat    = V4L2_SDR_FMT_CS8,
  50                 .buffersize     = SDR_CAP_SAMPLES_PER_BUF * 2,
  51         },
  52 };
  53
  54 static const unsigned int NUM_FORMATS = ARRAY_SIZE(formats);
  55
  56 static const struct v4l2_frequency_band bands_adc[] = {
  57         {
  58                 .tuner = 0,
  59                 .type = V4L2_TUNER_ADC,
  60                 .index = 0,
  61                 .capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
  62                 .rangelow   =  300000,
  63                 .rangehigh  =  300000,
  64         },
  65         {
  66                 .tuner = 0,
  67                 .type = V4L2_TUNER_ADC,
  68                 .index = 1,
  69                 .capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
  70                 .rangelow   =  900001,
  71                 .rangehigh  = 2800000,
  72         },
  73         {
  74                 .tuner = 0,
  75                 .type = V4L2_TUNER_ADC,
  76                 .index = 2,
  77                 .capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
  78                 .rangelow   = 3200000,
  79                 .rangehigh  = 3200000,
  80         },
  81 };
  82
  83 /* ADC band midpoints */
  84 #define BAND_ADC_0 ((bands_adc[0].rangehigh + bands_adc[1].rangelow) / 2)
  85 #define BAND_ADC_1 ((bands_adc[1].rangehigh + bands_adc[2].rangelow) / 2)
  86
  87 static const struct v4l2_frequency_band bands_fm[] = {
  88         {
  89                 .tuner = 1,
  90                 .type = V4L2_TUNER_RF,
  91                 .index = 0,
  92                 .capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
  93                 .rangelow   =    50000000,
  94                 .rangehigh  =  2000000000,
  95         },
  96 };
  97
  98 static void vivid_thread_sdr_cap_tick(struct vivid_dev *dev)
  99 {
 100         struct vivid_buffer *sdr_cap_buf = NULL;
 101
 102         dprintk(dev, 1, "SDR Capture Thread Tick\n");
 103
 104         /* Drop a certain percentage of buffers. */
 105         if (dev->perc_dropped_buffers &&
 106             prandom_u32_max(100) < dev->perc_dropped_buffers)
 107                 return;
 108
 109         spin_lock(&dev->slock);
 110         if (!list_empty(&dev->sdr_cap_active)) {
 111                 sdr_cap_buf = list_entry(dev->sdr_cap_active.next,
 112                                          struct vivid_buffer, list);
 113                 list_del(&sdr_cap_buf->list);
 114         }
 115         spin_unlock(&dev->slock);
 116
 117         if (sdr_cap_buf) {
 118                 sdr_cap_buf->vb.sequence = dev->sdr_cap_seq_count;
 119                 vivid_sdr_cap_process(dev, sdr_cap_buf);
 120                 sdr_cap_buf->vb.vb2_buf.timestamp =
 121                         ktime_get_ns() + dev->time_wrap_offset;
 122                 vb2_buffer_done(&sdr_cap_buf->vb.vb2_buf, dev->dqbuf_error ?
 123                                 VB2_BUF_STATE_ERROR : VB2_BUF_STATE_DONE);
 124                 dev->dqbuf_error = false;
 125         }
 126 }
 127
 128 static int vivid_thread_sdr_cap(void *data)
 129 {
 130         struct vivid_dev *dev = data;
 131         u64 samples_since_start;
 132         u64 buffers_since_start;
 133         u64 next_jiffies_since_start;
 134         unsigned long jiffies_since_start;
 135         unsigned long cur_jiffies;
 136         unsigned wait_jiffies;
 137
 138         dprintk(dev, 1, "SDR Capture Thread Start\n");
 139
 140         set_freezable();
 141
 142         /* Resets frame counters */
 143         dev->sdr_cap_seq_offset = 0;
 144         if (dev->seq_wrap)
 145                 dev->sdr_cap_seq_offset = 0xffffff80U;
 146         dev->jiffies_sdr_cap = jiffies;
 147         dev->sdr_cap_seq_resync = false;
 148
 149         for (;;) {
 150                 try_to_freeze();
 151                 if (kthread_should_stop())
 152                         break;
 153
 154                 mutex_lock(&dev->mutex);
 155                 cur_jiffies = jiffies;
 156                 if (dev->sdr_cap_seq_resync) {
 157                         dev->jiffies_sdr_cap = cur_jiffies;
 158                         dev->sdr_cap_seq_offset = dev->sdr_cap_seq_count + 1;
 159                         dev->sdr_cap_seq_count = 0;
 160                         dev->sdr_cap_seq_resync = false;
 161                 }
 162                 /* Calculate the number of jiffies since we started streaming */
 163                 jiffies_since_start = cur_jiffies - dev->jiffies_sdr_cap;
 164                 /* Get the number of buffers streamed since the start */
 165                 buffers_since_start =
 166                         (u64)jiffies_since_start * dev->sdr_adc_freq +
 167                                       (HZ * SDR_CAP_SAMPLES_PER_BUF) / 2;
 168                 do_div(buffers_since_start, HZ * SDR_CAP_SAMPLES_PER_BUF);
 169
 170                 /*
 171                  * After more than 0xf0000000 (rounded down to a multiple of
 172                  * 'jiffies-per-day' to ease jiffies_to_msecs calculation)
 173                  * jiffies have passed since we started streaming reset the
 174                  * counters and keep track of the sequence offset.
 175                  */
 176                 if (jiffies_since_start > JIFFIES_RESYNC) {
 177                         dev->jiffies_sdr_cap = cur_jiffies;
 178                         dev->sdr_cap_seq_offset = buffers_since_start;
 179                         buffers_since_start = 0;
 180                 }
 181                 dev->sdr_cap_seq_count =
 182                         buffers_since_start + dev->sdr_cap_seq_offset;
 183
 184                 vivid_thread_sdr_cap_tick(dev);
 185                 mutex_unlock(&dev->mutex);
 186
 187                 /*
 188                  * Calculate the number of samples streamed since we started,
 189                  * not including the current buffer.
 190                  */
 191                 samples_since_start = buffers_since_start * SDR_CAP_SAMPLES_PER_BUF;
 192
 193                 /* And the number of jiffies since we started */
 194                 jiffies_since_start = jiffies - dev->jiffies_sdr_cap;
 195
 196                 /* Increase by the number of samples in one buffer */
 197                 samples_since_start += SDR_CAP_SAMPLES_PER_BUF;
 198                 /*
 199                  * Calculate when that next buffer is supposed to start
 200                  * in jiffies since we started streaming.
 201                  */
 202                 next_jiffies_since_start = samples_since_start * HZ +
 203                                            dev->sdr_adc_freq / 2;
 204                 do_div(next_jiffies_since_start, dev->sdr_adc_freq);
 205                 /* If it is in the past, then just schedule asap */
 206                 if (next_jiffies_since_start < jiffies_since_start)
 207                         next_jiffies_since_start = jiffies_since_start;
 208
 209                 wait_jiffies = next_jiffies_since_start - jiffies_since_start;
 210                 schedule_timeout_interruptible(wait_jiffies ? wait_jiffies : 1);
 211         }
 212         dprintk(dev, 1, "SDR Capture Thread End\n");
 213         return 0;
 214 }
 215
 216 static int sdr_cap_queue_setup(struct vb2_queue *vq,
 217                        unsigned *nbuffers, unsigned *nplanes,
 218                        unsigned sizes[], void *alloc_ctxs[])
 219 {
 220         /* 2 = max 16-bit sample returned */
 221         sizes[0] = SDR_CAP_SAMPLES_PER_BUF * 2;
 222         *nplanes = 1;
 223         return 0;
 224 }
 225
 226 static int sdr_cap_buf_prepare(struct vb2_buffer *vb)
 227 {
 228         struct vivid_dev *dev = vb2_get_drv_priv(vb->vb2_queue);
 229         unsigned size = SDR_CAP_SAMPLES_PER_BUF * 2;
 230
 231         dprintk(dev, 1, "%s\n", __func__);
 232
 233         if (dev->buf_prepare_error) {
 234                 /*
 235                  * Error injection: test what happens if buf_prepare() returns
 236                  * an error.
 237                  */
 238                 dev->buf_prepare_error = false;
 239                 return -EINVAL;
 240         }
 241         if (vb2_plane_size(vb, 0) < size) {
 242                 dprintk(dev, 1, "%s data will not fit into plane (%lu < %u)\n",
 243                                 __func__, vb2_plane_size(vb, 0), size);
 244                 return -EINVAL;
 245         }
 246         vb2_set_plane_payload(vb, 0, size);
 247
 248         return 0;
 249 }
 250
 251 static void sdr_cap_buf_queue(struct vb2_buffer *vb)
 252 {
 253         struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
 254         struct vivid_dev *dev = vb2_get_drv_priv(vb->vb2_queue);
 255         struct vivid_buffer *buf = container_of(vbuf, struct vivid_buffer, vb);
 256
 257         dprintk(dev, 1, "%s\n", __func__);
 258
 259         spin_lock(&dev->slock);
 260         list_add_tail(&buf->list, &dev->sdr_cap_active);
 261         spin_unlock(&dev->slock);
 262 }
 263
 264 static int sdr_cap_start_streaming(struct vb2_queue *vq, unsigned count)
 265 {
 266         struct vivid_dev *dev = vb2_get_drv_priv(vq);
 267         int err = 0;
 268
 269         dprintk(dev, 1, "%s\n", __func__);
 270         dev->sdr_cap_seq_count = 0;
 271         if (dev->start_streaming_error) {
 272                 dev->start_streaming_error = false;
 273                 err = -EINVAL;
 274         } else if (dev->kthread_sdr_cap == NULL) {
 275                 dev->kthread_sdr_cap = kthread_run(vivid_thread_sdr_cap, dev,
 276                                 "%s-sdr-cap", dev->v4l2_dev.name);
 277
 278                 if (IS_ERR(dev->kthread_sdr_cap)) {
 279                         v4l2_err(&dev->v4l2_dev, "kernel_thread() failed\n");
 280                         err = PTR_ERR(dev->kthread_sdr_cap);
 281                         dev->kthread_sdr_cap = NULL;
 282                 }
 283         }
 284         if (err) {
 285                 struct vivid_buffer *buf, *tmp;
 286
 287                 list_for_each_entry_safe(buf, tmp, &dev->sdr_cap_active, list) {
 288                         list_del(&buf->list);
 289                         vb2_buffer_done(&buf->vb.vb2_buf,
 290                                         VB2_BUF_STATE_QUEUED);
 291                 }
 292         }
 293         return err;
 294 }
 295
 296 /* abort streaming and wait for last buffer */
 297 static void sdr_cap_stop_streaming(struct vb2_queue *vq)
 298 {
 299         struct vivid_dev *dev = vb2_get_drv_priv(vq);
 300
 301         if (dev->kthread_sdr_cap == NULL)
 302                 return;
 303
 304         while (!list_empty(&dev->sdr_cap_active)) {
 305                 struct vivid_buffer *buf;
 306
 307                 buf = list_entry(dev->sdr_cap_active.next,
 308                                 struct vivid_buffer, list);
 309                 list_del(&buf->list);
 310                 vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
 311         }
 312
 313         /* shutdown control thread */
 314         mutex_unlock(&dev->mutex);
 315         kthread_stop(dev->kthread_sdr_cap);
 316         dev->kthread_sdr_cap = NULL;
 317         mutex_lock(&dev->mutex);
 318 }
 319
 320 const struct vb2_ops vivid_sdr_cap_qops = {
 321         .queue_setup            = sdr_cap_queue_setup,
 322         .buf_prepare            = sdr_cap_buf_prepare,
 323         .buf_queue              = sdr_cap_buf_queue,
 324         .start_streaming        = sdr_cap_start_streaming,
 325         .stop_streaming         = sdr_cap_stop_streaming,
 326         .wait_prepare           = vb2_ops_wait_prepare,
 327         .wait_finish            = vb2_ops_wait_finish,
 328 };
 329
 330 int vivid_sdr_enum_freq_bands(struct file *file, void *fh,
 331                 struct v4l2_frequency_band *band)
 332 {
 333         switch (band->tuner) {
 334         case 0:
 335                 if (band->index >= ARRAY_SIZE(bands_adc))
 336                         return -EINVAL;
 337                 *band = bands_adc[band->index];
 338                 return 0;
 339         case 1:
 340                 if (band->index >= ARRAY_SIZE(bands_fm))
 341                         return -EINVAL;
 342                 *band = bands_fm[band->index];
 343                 return 0;
 344         default:
 345                 return -EINVAL;
 346         }
 347 }
 348
 349 int vivid_sdr_g_frequency(struct file *file, void *fh,
 350                 struct v4l2_frequency *vf)
 351 {
 352         struct vivid_dev *dev = video_drvdata(file);
 353
 354         switch (vf->tuner) {
 355         case 0:
 356                 vf->frequency = dev->sdr_adc_freq;
 357                 vf->type = V4L2_TUNER_ADC;
 358                 return 0;
 359         case 1:
 360                 vf->frequency = dev->sdr_fm_freq;
 361                 vf->type = V4L2_TUNER_RF;
 362                 return 0;
 363         default:
 364                 return -EINVAL;
 365         }
 366 }
 367
 368 int vivid_sdr_s_frequency(struct file *file, void *fh,
 369                 const struct v4l2_frequency *vf)
 370 {
 371         struct vivid_dev *dev = video_drvdata(file);
 372         unsigned freq = vf->frequency;
 373         unsigned band;
 374
 375         switch (vf->tuner) {
 376         case 0:
 377                 if (vf->type != V4L2_TUNER_ADC)
 378                         return -EINVAL;
 379                 if (freq < BAND_ADC_0)
 380                         band = 0;
 381                 else if (freq < BAND_ADC_1)
 382                         band = 1;
 383                 else
 384                         band = 2;
 385
 386                 freq = clamp_t(unsigned, freq,
 387                                 bands_adc[band].rangelow,
 388                                 bands_adc[band].rangehigh);
 389
 390                 if (vb2_is_streaming(&dev->vb_sdr_cap_q) &&
 391                     freq != dev->sdr_adc_freq) {
 392                         /* resync the thread's timings */
 393                         dev->sdr_cap_seq_resync = true;
 394                 }
 395                 dev->sdr_adc_freq = freq;
 396                 return 0;
 397         case 1:
 398                 if (vf->type != V4L2_TUNER_RF)
 399                         return -EINVAL;
 400                 dev->sdr_fm_freq = clamp_t(unsigned, freq,
 401                                 bands_fm[0].rangelow,
 402                                 bands_fm[0].rangehigh);
 403                 return 0;
 404         default:
 405                 return -EINVAL;
 406         }
 407 }
 408
 409 int vivid_sdr_g_tuner(struct file *file, void *fh, struct v4l2_tuner *vt)
 410 {
 411         switch (vt->index) {
 412         case 0:
 413                 strlcpy(vt->name, "ADC", sizeof(vt->name));
 414                 vt->type = V4L2_TUNER_ADC;
 415                 vt->capability =
 416                         V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS;
 417                 vt->rangelow = bands_adc[0].rangelow;
 418                 vt->rangehigh = bands_adc[2].rangehigh;
 419                 return 0;
 420         case 1:
 421                 strlcpy(vt->name, "RF", sizeof(vt->name));
 422                 vt->type = V4L2_TUNER_RF;
 423                 vt->capability =
 424                         V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS;
 425                 vt->rangelow = bands_fm[0].rangelow;
 426                 vt->rangehigh = bands_fm[0].rangehigh;
 427                 return 0;
 428         default:
 429                 return -EINVAL;
 430         }
 431 }
 432
 433 int vivid_sdr_s_tuner(struct file *file, void *fh, const struct v4l2_tuner *vt)
 434 {
 435         if (vt->index > 1)
 436                 return -EINVAL;
 437         return 0;
 438 }
 439
 440 int vidioc_enum_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_fmtdesc *f)
 441 {
 442         if (f->index >= ARRAY_SIZE(formats))
 443                 return -EINVAL;
 444         f->pixelformat = formats[f->index].pixelformat;
 445         return 0;
 446 }
 447
 448 int vidioc_g_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_format *f)
 449 {
 450         struct vivid_dev *dev = video_drvdata(file);
 451
 452         f->fmt.sdr.pixelformat = dev->sdr_pixelformat;
 453         f->fmt.sdr.buffersize = dev->sdr_buffersize;
 454         memset(f->fmt.sdr.reserved, 0, sizeof(f->fmt.sdr.reserved));
 455         return 0;
 456 }
 457
 458 int vidioc_s_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_format *f)
 459 {
 460         struct vivid_dev *dev = video_drvdata(file);
 461         struct vb2_queue *q = &dev->vb_sdr_cap_q;
 462         int i;
 463
 464         if (vb2_is_busy(q))
 465                 return -EBUSY;
 466
 467         memset(f->fmt.sdr.reserved, 0, sizeof(f->fmt.sdr.reserved));
 468         for (i = 0; i < ARRAY_SIZE(formats); i++) {
 469                 if (formats[i].pixelformat == f->fmt.sdr.pixelformat) {
 470                         dev->sdr_pixelformat = formats[i].pixelformat;
 471                         dev->sdr_buffersize = formats[i].buffersize;
 472                         f->fmt.sdr.buffersize = formats[i].buffersize;
 473                         return 0;
 474                 }
 475         }
 476         dev->sdr_pixelformat = formats[0].pixelformat;
 477         dev->sdr_buffersize = formats[0].buffersize;
 478         f->fmt.sdr.pixelformat = formats[0].pixelformat;
 479         f->fmt.sdr.buffersize = formats[0].buffersize;
 480         return 0;
 481 }
 482
 483 int vidioc_try_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_format *f)
 484 {
 485         int i;
 486
 487         memset(f->fmt.sdr.reserved, 0, sizeof(f->fmt.sdr.reserved));
 488         for (i = 0; i < ARRAY_SIZE(formats); i++) {
 489                 if (formats[i].pixelformat == f->fmt.sdr.pixelformat) {
 490                         f->fmt.sdr.buffersize = formats[i].buffersize;
 491                         return 0;
 492                 }
 493         }
 494         f->fmt.sdr.pixelformat = formats[0].pixelformat;
 495         f->fmt.sdr.buffersize = formats[0].buffersize;
 496         return 0;
 497 }
 498
 499 #define FIXP_N    (15)
 500 #define FIXP_FRAC (1 << FIXP_N)
 501 #define FIXP_2PI  ((int)(2 * 3.141592653589 * FIXP_FRAC))
 502 #define M_100000PI (3.14159 * 100000)
 503
 504 void vivid_sdr_cap_process(struct vivid_dev *dev, struct vivid_buffer *buf)
 505 {
 506         u8 *vbuf = vb2_plane_vaddr(&buf->vb.vb2_buf, 0);
 507         unsigned long i;
 508         unsigned long plane_size = vb2_plane_size(&buf->vb.vb2_buf, 0);
 509         s64 s64tmp;
 510         s32 src_phase_step;
 511         s32 mod_phase_step;
 512         s32 fixp_i;
 513         s32 fixp_q;
 514
 515         /* calculate phase step */
 516         #define BEEP_FREQ 1000 /* 1kHz beep */
 517         src_phase_step = DIV_ROUND_CLOSEST(FIXP_2PI * BEEP_FREQ,
 518                                            dev->sdr_adc_freq);
 519
 520         for (i = 0; i < plane_size; i += 2) {
 521                 mod_phase_step = fixp_cos32_rad(dev->sdr_fixp_src_phase,
 522                                                 FIXP_2PI) >> (31 - FIXP_N);
 523
 524                 dev->sdr_fixp_src_phase += src_phase_step;
 525                 s64tmp = (s64) mod_phase_step * dev->sdr_fm_deviation;
 526                 dev->sdr_fixp_mod_phase += div_s64(s64tmp, M_100000PI);
 527
 528                 /*
 529                  * Transfer phase angle to [0, 2xPI] in order to avoid variable
 530                  * overflow and make it suitable for cosine implementation
 531                  * used, which does not support negative angles.
 532                  */
 533                 dev->sdr_fixp_src_phase %= FIXP_2PI;
 534                 dev->sdr_fixp_mod_phase %= FIXP_2PI;
 535
 536                 if (dev->sdr_fixp_mod_phase < 0)
 537                         dev->sdr_fixp_mod_phase += FIXP_2PI;
 538
 539                 fixp_i = fixp_cos32_rad(dev->sdr_fixp_mod_phase, FIXP_2PI);
 540                 fixp_q = fixp_sin32_rad(dev->sdr_fixp_mod_phase, FIXP_2PI);
 541
 542                 /* Normalize fraction values represented with 32 bit precision
 543                  * to fixed point representation with FIXP_N bits */
 544                 fixp_i >>= (31 - FIXP_N);
 545                 fixp_q >>= (31 - FIXP_N);
 546
 547                 switch (dev->sdr_pixelformat) {
 548                 case V4L2_SDR_FMT_CU8:
 549                         /* convert 'fixp float' to u8 [0, +255] */
 550                         /* u8 = X * 127.5 + 127.5; X is float [-1.0, +1.0] */
 551                         fixp_i = fixp_i * 1275 + FIXP_FRAC * 1275;
 552                         fixp_q = fixp_q * 1275 + FIXP_FRAC * 1275;
 553                         *vbuf++ = DIV_ROUND_CLOSEST(fixp_i, FIXP_FRAC * 10);
 554                         *vbuf++ = DIV_ROUND_CLOSEST(fixp_q, FIXP_FRAC * 10);
 555                         break;
 556                 case V4L2_SDR_FMT_CS8:
 557                         /* convert 'fixp float' to s8 [-128, +127] */
 558                         /* s8 = X * 127.5 - 0.5; X is float [-1.0, +1.0] */
 559                         fixp_i = fixp_i * 1275 - FIXP_FRAC * 5;
 560                         fixp_q = fixp_q * 1275 - FIXP_FRAC * 5;
 561                         *vbuf++ = DIV_ROUND_CLOSEST(fixp_i, FIXP_FRAC * 10);
 562                         *vbuf++ = DIV_ROUND_CLOSEST(fixp_q, FIXP_FRAC * 10);
 563                         break;
 564                 default:
 565                         break;
 566                 }
 567         }
 568 }