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/videodev2.h>
  26 #include <linux/v4l2-dv-timings.h>
  27 #include <media/v4l2-common.h>
  28 #include <media/v4l2-event.h>
  29 #include <media/v4l2-dv-timings.h>
  30 #include <linux/fixp-arith.h>
  31
  32 #include "vivid-core.h"
  33 #include "vivid-ctrls.h"
  34 #include "vivid-sdr-cap.h"
  35
  36 /* stream formats */
  37 struct vivid_format {
  38         u32     pixelformat;
  39         u32     buffersize;
  40 };
  41
  42 /* format descriptions for capture and preview */
  43 static struct vivid_format formats[] = {
  44         {
  45                 .pixelformat    = V4L2_SDR_FMT_CU8,
  46                 .buffersize     = SDR_CAP_SAMPLES_PER_BUF * 2,
  47         }, {
  48                 .pixelformat    = V4L2_SDR_FMT_CS8,
  49                 .buffersize     = SDR_CAP_SAMPLES_PER_BUF * 2,
  50         },
  51 };
  52
  53 static const unsigned int NUM_FORMATS = ARRAY_SIZE(formats);
  54
  55 static const struct v4l2_frequency_band bands_adc[] = {
  56         {
  57                 .tuner = 0,
  58                 .type = V4L2_TUNER_ADC,
  59                 .index = 0,
  60                 .capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
  61                 .rangelow   =  300000,
  62                 .rangehigh  =  300000,
  63         },
  64         {
  65                 .tuner = 0,
  66                 .type = V4L2_TUNER_ADC,
  67                 .index = 1,
  68                 .capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
  69                 .rangelow   =  900001,
  70                 .rangehigh  = 2800000,
  71         },
  72         {
  73                 .tuner = 0,
  74                 .type = V4L2_TUNER_ADC,
  75                 .index = 2,
  76                 .capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
  77                 .rangelow   = 3200000,
  78                 .rangehigh  = 3200000,
  79         },
  80 };
  81
  82 /* ADC band midpoints */
  83 #define BAND_ADC_0 ((bands_adc[0].rangehigh + bands_adc[1].rangelow) / 2)
  84 #define BAND_ADC_1 ((bands_adc[1].rangehigh + bands_adc[2].rangelow) / 2)
  85
  86 static const struct v4l2_frequency_band bands_fm[] = {
  87         {
  88                 .tuner = 1,
  89                 .type = V4L2_TUNER_RF,
  90                 .index = 0,
  91                 .capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
  92                 .rangelow   =    50000000,
  93                 .rangehigh  =  2000000000,
  94         },
  95 };
  96
  97 static void vivid_thread_sdr_cap_tick(struct vivid_dev *dev)
  98 {
  99         struct vivid_buffer *sdr_cap_buf = NULL;
 100
 101         dprintk(dev, 1, "SDR Capture Thread Tick\n");
 102
 103         /* Drop a certain percentage of buffers. */
 104         if (dev->perc_dropped_buffers &&
 105             prandom_u32_max(100) < dev->perc_dropped_buffers)
 106                 return;
 107
 108         spin_lock(&dev->slock);
 109         if (!list_empty(&dev->sdr_cap_active)) {
 110                 sdr_cap_buf = list_entry(dev->sdr_cap_active.next,
 111                                          struct vivid_buffer, list);
 112                 list_del(&sdr_cap_buf->list);
 113         }
 114         spin_unlock(&dev->slock);
 115
 116         if (sdr_cap_buf) {
 117                 sdr_cap_buf->vb.v4l2_buf.sequence = dev->sdr_cap_seq_count;
 118                 vivid_sdr_cap_process(dev, sdr_cap_buf);
 119                 v4l2_get_timestamp(&sdr_cap_buf->vb.v4l2_buf.timestamp);
 120                 sdr_cap_buf->vb.v4l2_buf.timestamp.tv_sec += dev->time_wrap_offset;
 121                 vb2_buffer_done(&sdr_cap_buf->vb, dev->dqbuf_error ?
 122                                 VB2_BUF_STATE_ERROR : VB2_BUF_STATE_DONE);
 123                 dev->dqbuf_error = false;
 124         }
 125 }
 126
 127 static int vivid_thread_sdr_cap(void *data)
 128 {
 129         struct vivid_dev *dev = data;
 130         u64 samples_since_start;
 131         u64 buffers_since_start;
 132         u64 next_jiffies_since_start;
 133         unsigned long jiffies_since_start;
 134         unsigned long cur_jiffies;
 135         unsigned wait_jiffies;
 136
 137         dprintk(dev, 1, "SDR Capture Thread Start\n");
 138
 139         set_freezable();
 140
 141         /* Resets frame counters */
 142         dev->sdr_cap_seq_offset = 0;
 143         if (dev->seq_wrap)
 144                 dev->sdr_cap_seq_offset = 0xffffff80U;
 145         dev->jiffies_sdr_cap = jiffies;
 146         dev->sdr_cap_seq_resync = false;
 147
 148         for (;;) {
 149                 try_to_freeze();
 150                 if (kthread_should_stop())
 151                         break;
 152
 153                 mutex_lock(&dev->mutex);
 154                 cur_jiffies = jiffies;
 155                 if (dev->sdr_cap_seq_resync) {
 156                         dev->jiffies_sdr_cap = cur_jiffies;
 157                         dev->sdr_cap_seq_offset = dev->sdr_cap_seq_count + 1;
 158                         dev->sdr_cap_seq_count = 0;
 159                         dev->sdr_cap_seq_resync = false;
 160                 }
 161                 /* Calculate the number of jiffies since we started streaming */
 162                 jiffies_since_start = cur_jiffies - dev->jiffies_sdr_cap;
 163                 /* Get the number of buffers streamed since the start */
 164                 buffers_since_start = (u64)jiffies_since_start * dev->sdr_adc_freq +
 165                                       (HZ * SDR_CAP_SAMPLES_PER_BUF) / 2;
 166                 do_div(buffers_since_start, HZ * SDR_CAP_SAMPLES_PER_BUF);
 167
 168                 /*
 169                  * After more than 0xf0000000 (rounded down to a multiple of
 170                  * 'jiffies-per-day' to ease jiffies_to_msecs calculation)
 171                  * jiffies have passed since we started streaming reset the
 172                  * counters and keep track of the sequence offset.
 173                  */
 174                 if (jiffies_since_start > JIFFIES_RESYNC) {
 175                         dev->jiffies_sdr_cap = cur_jiffies;
 176                         dev->sdr_cap_seq_offset = buffers_since_start;
 177                         buffers_since_start = 0;
 178                 }
 179                 dev->sdr_cap_seq_count = buffers_since_start + dev->sdr_cap_seq_offset;
 180
 181                 vivid_thread_sdr_cap_tick(dev);
 182                 mutex_unlock(&dev->mutex);
 183
 184                 /*
 185                  * Calculate the number of samples streamed since we started,
 186                  * not including the current buffer.
 187                  */
 188                 samples_since_start = buffers_since_start * SDR_CAP_SAMPLES_PER_BUF;
 189
 190                 /* And the number of jiffies since we started */
 191                 jiffies_since_start = jiffies - dev->jiffies_sdr_cap;
 192
 193                 /* Increase by the number of samples in one buffer */
 194                 samples_since_start += SDR_CAP_SAMPLES_PER_BUF;
 195                 /*
 196                  * Calculate when that next buffer is supposed to start
 197                  * in jiffies since we started streaming.
 198                  */
 199                 next_jiffies_since_start = samples_since_start * HZ +
 200                                            dev->sdr_adc_freq / 2;
 201                 do_div(next_jiffies_since_start, dev->sdr_adc_freq);
 202                 /* If it is in the past, then just schedule asap */
 203                 if (next_jiffies_since_start < jiffies_since_start)
 204                         next_jiffies_since_start = jiffies_since_start;
 205
 206                 wait_jiffies = next_jiffies_since_start - jiffies_since_start;
 207                 schedule_timeout_interruptible(wait_jiffies ? wait_jiffies : 1);
 208         }
 209         dprintk(dev, 1, "SDR Capture Thread End\n");
 210         return 0;
 211 }
 212
 213 static int sdr_cap_queue_setup(struct vb2_queue *vq, const struct v4l2_format *fmt,
 214                        unsigned *nbuffers, unsigned *nplanes,
 215                        unsigned sizes[], void *alloc_ctxs[])
 216 {
 217         /* 2 = max 16-bit sample returned */
 218         sizes[0] = SDR_CAP_SAMPLES_PER_BUF * 2;
 219         *nplanes = 1;
 220         return 0;
 221 }
 222
 223 static int sdr_cap_buf_prepare(struct vb2_buffer *vb)
 224 {
 225         struct vivid_dev *dev = vb2_get_drv_priv(vb->vb2_queue);
 226         unsigned size = SDR_CAP_SAMPLES_PER_BUF * 2;
 227
 228         dprintk(dev, 1, "%s\n", __func__);
 229
 230         if (dev->buf_prepare_error) {
 231                 /*
 232                  * Error injection: test what happens if buf_prepare() returns
 233                  * an error.
 234                  */
 235                 dev->buf_prepare_error = false;
 236                 return -EINVAL;
 237         }
 238         if (vb2_plane_size(vb, 0) < size) {
 239                 dprintk(dev, 1, "%s data will not fit into plane (%lu < %u)\n",
 240                                 __func__, vb2_plane_size(vb, 0), size);
 241                 return -EINVAL;
 242         }
 243         vb2_set_plane_payload(vb, 0, size);
 244
 245         return 0;
 246 }
 247
 248 static void sdr_cap_buf_queue(struct vb2_buffer *vb)
 249 {
 250         struct vivid_dev *dev = vb2_get_drv_priv(vb->vb2_queue);
 251         struct vivid_buffer *buf = container_of(vb, struct vivid_buffer, vb);
 252
 253         dprintk(dev, 1, "%s\n", __func__);
 254
 255         spin_lock(&dev->slock);
 256         list_add_tail(&buf->list, &dev->sdr_cap_active);
 257         spin_unlock(&dev->slock);
 258 }
 259
 260 static int sdr_cap_start_streaming(struct vb2_queue *vq, unsigned count)
 261 {
 262         struct vivid_dev *dev = vb2_get_drv_priv(vq);
 263         int err = 0;
 264
 265         dprintk(dev, 1, "%s\n", __func__);
 266         dev->sdr_cap_seq_count = 0;
 267         if (dev->start_streaming_error) {
 268                 dev->start_streaming_error = false;
 269                 err = -EINVAL;
 270         } else if (dev->kthread_sdr_cap == NULL) {
 271                 dev->kthread_sdr_cap = kthread_run(vivid_thread_sdr_cap, dev,
 272                                 "%s-sdr-cap", dev->v4l2_dev.name);
 273
 274                 if (IS_ERR(dev->kthread_sdr_cap)) {
 275                         v4l2_err(&dev->v4l2_dev, "kernel_thread() failed\n");
 276                         err = PTR_ERR(dev->kthread_sdr_cap);
 277                         dev->kthread_sdr_cap = NULL;
 278                 }
 279         }
 280         if (err) {
 281                 struct vivid_buffer *buf, *tmp;
 282
 283                 list_for_each_entry_safe(buf, tmp, &dev->sdr_cap_active, list) {
 284                         list_del(&buf->list);
 285                         vb2_buffer_done(&buf->vb, VB2_BUF_STATE_QUEUED);
 286                 }
 287         }
 288         return err;
 289 }
 290
 291 /* abort streaming and wait for last buffer */
 292 static void sdr_cap_stop_streaming(struct vb2_queue *vq)
 293 {
 294         struct vivid_dev *dev = vb2_get_drv_priv(vq);
 295
 296         if (dev->kthread_sdr_cap == NULL)
 297                 return;
 298
 299         while (!list_empty(&dev->sdr_cap_active)) {
 300                 struct vivid_buffer *buf;
 301
 302                 buf = list_entry(dev->sdr_cap_active.next, struct vivid_buffer, list);
 303                 list_del(&buf->list);
 304                 vb2_buffer_done(&buf->vb, VB2_BUF_STATE_ERROR);
 305         }
 306
 307         /* shutdown control thread */
 308         mutex_unlock(&dev->mutex);
 309         kthread_stop(dev->kthread_sdr_cap);
 310         dev->kthread_sdr_cap = NULL;
 311         mutex_lock(&dev->mutex);
 312 }
 313
 314 const struct vb2_ops vivid_sdr_cap_qops = {
 315         .queue_setup            = sdr_cap_queue_setup,
 316         .buf_prepare            = sdr_cap_buf_prepare,
 317         .buf_queue              = sdr_cap_buf_queue,
 318         .start_streaming        = sdr_cap_start_streaming,
 319         .stop_streaming         = sdr_cap_stop_streaming,
 320         .wait_prepare           = vb2_ops_wait_prepare,
 321         .wait_finish            = vb2_ops_wait_finish,
 322 };
 323
 324 int vivid_sdr_enum_freq_bands(struct file *file, void *fh, struct v4l2_frequency_band *band)
 325 {
 326         switch (band->tuner) {
 327         case 0:
 328                 if (band->index >= ARRAY_SIZE(bands_adc))
 329                         return -EINVAL;
 330                 *band = bands_adc[band->index];
 331                 return 0;
 332         case 1:
 333                 if (band->index >= ARRAY_SIZE(bands_fm))
 334                         return -EINVAL;
 335                 *band = bands_fm[band->index];
 336                 return 0;
 337         default:
 338                 return -EINVAL;
 339         }
 340 }
 341
 342 int vivid_sdr_g_frequency(struct file *file, void *fh, struct v4l2_frequency *vf)
 343 {
 344         struct vivid_dev *dev = video_drvdata(file);
 345
 346         switch (vf->tuner) {
 347         case 0:
 348                 vf->frequency = dev->sdr_adc_freq;
 349                 vf->type = V4L2_TUNER_ADC;
 350                 return 0;
 351         case 1:
 352                 vf->frequency = dev->sdr_fm_freq;
 353                 vf->type = V4L2_TUNER_RF;
 354                 return 0;
 355         default:
 356                 return -EINVAL;
 357         }
 358 }
 359
 360 int vivid_sdr_s_frequency(struct file *file, void *fh, const struct v4l2_frequency *vf)
 361 {
 362         struct vivid_dev *dev = video_drvdata(file);
 363         unsigned freq = vf->frequency;
 364         unsigned band;
 365
 366         switch (vf->tuner) {
 367         case 0:
 368                 if (vf->type != V4L2_TUNER_ADC)
 369                         return -EINVAL;
 370                 if (freq < BAND_ADC_0)
 371                         band = 0;
 372                 else if (freq < BAND_ADC_1)
 373                         band = 1;
 374                 else
 375                         band = 2;
 376
 377                 freq = clamp_t(unsigned, freq,
 378                                 bands_adc[band].rangelow,
 379                                 bands_adc[band].rangehigh);
 380
 381                 if (vb2_is_streaming(&dev->vb_sdr_cap_q) &&
 382                     freq != dev->sdr_adc_freq) {
 383                         /* resync the thread's timings */
 384                         dev->sdr_cap_seq_resync = true;
 385                 }
 386                 dev->sdr_adc_freq = freq;
 387                 return 0;
 388         case 1:
 389                 if (vf->type != V4L2_TUNER_RF)
 390                         return -EINVAL;
 391                 dev->sdr_fm_freq = clamp_t(unsigned, freq,
 392                                 bands_fm[0].rangelow,
 393                                 bands_fm[0].rangehigh);
 394                 return 0;
 395         default:
 396                 return -EINVAL;
 397         }
 398 }
 399
 400 int vivid_sdr_g_tuner(struct file *file, void *fh, struct v4l2_tuner *vt)
 401 {
 402         switch (vt->index) {
 403         case 0:
 404                 strlcpy(vt->name, "ADC", sizeof(vt->name));
 405                 vt->type = V4L2_TUNER_ADC;
 406                 vt->capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS;
 407                 vt->rangelow = bands_adc[0].rangelow;
 408                 vt->rangehigh = bands_adc[2].rangehigh;
 409                 return 0;
 410         case 1:
 411                 strlcpy(vt->name, "RF", sizeof(vt->name));
 412                 vt->type = V4L2_TUNER_RF;
 413                 vt->capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS;
 414                 vt->rangelow = bands_fm[0].rangelow;
 415                 vt->rangehigh = bands_fm[0].rangehigh;
 416                 return 0;
 417         default:
 418                 return -EINVAL;
 419         }
 420 }
 421
 422 int vivid_sdr_s_tuner(struct file *file, void *fh, const struct v4l2_tuner *vt)
 423 {
 424         if (vt->index > 1)
 425                 return -EINVAL;
 426         return 0;
 427 }
 428
 429 int vidioc_enum_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_fmtdesc *f)
 430 {
 431         if (f->index >= ARRAY_SIZE(formats))
 432                 return -EINVAL;
 433         f->pixelformat = formats[f->index].pixelformat;
 434         return 0;
 435 }
 436
 437 int vidioc_g_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_format *f)
 438 {
 439         struct vivid_dev *dev = video_drvdata(file);
 440
 441         f->fmt.sdr.pixelformat = dev->sdr_pixelformat;
 442         f->fmt.sdr.buffersize = dev->sdr_buffersize;
 443         memset(f->fmt.sdr.reserved, 0, sizeof(f->fmt.sdr.reserved));
 444         return 0;
 445 }
 446
 447 int vidioc_s_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_format *f)
 448 {
 449         struct vivid_dev *dev = video_drvdata(file);
 450         struct vb2_queue *q = &dev->vb_sdr_cap_q;
 451         int i;
 452
 453         if (vb2_is_busy(q))
 454                 return -EBUSY;
 455
 456         memset(f->fmt.sdr.reserved, 0, sizeof(f->fmt.sdr.reserved));
 457         for (i = 0; i < ARRAY_SIZE(formats); i++) {
 458                 if (formats[i].pixelformat == f->fmt.sdr.pixelformat) {
 459                         dev->sdr_pixelformat = formats[i].pixelformat;
 460                         dev->sdr_buffersize = formats[i].buffersize;
 461                         f->fmt.sdr.buffersize = formats[i].buffersize;
 462                         return 0;
 463                 }
 464         }
 465         dev->sdr_pixelformat = formats[0].pixelformat;
 466         dev->sdr_buffersize = formats[0].buffersize;
 467         f->fmt.sdr.pixelformat = formats[0].pixelformat;
 468         f->fmt.sdr.buffersize = formats[0].buffersize;
 469         return 0;
 470 }
 471
 472 int vidioc_try_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_format *f)
 473 {
 474         int i;
 475
 476         memset(f->fmt.sdr.reserved, 0, sizeof(f->fmt.sdr.reserved));
 477         for (i = 0; i < ARRAY_SIZE(formats); i++) {
 478                 if (formats[i].pixelformat == f->fmt.sdr.pixelformat) {
 479                         f->fmt.sdr.buffersize = formats[i].buffersize;
 480                         return 0;
 481                 }
 482         }
 483         f->fmt.sdr.pixelformat = formats[0].pixelformat;
 484         f->fmt.sdr.buffersize = formats[0].buffersize;
 485         return 0;
 486 }
 487
 488 #define FIXP_N    (15)
 489 #define FIXP_FRAC (1 << FIXP_N)
 490 #define FIXP_2PI  ((int)(2 * 3.141592653589 * FIXP_FRAC))
 491
 492 void vivid_sdr_cap_process(struct vivid_dev *dev, struct vivid_buffer *buf)
 493 {
 494         u8 *vbuf = vb2_plane_vaddr(&buf->vb, 0);
 495         unsigned long i;
 496         unsigned long plane_size = vb2_plane_size(&buf->vb, 0);
 497         s32 src_phase_step;
 498         s32 mod_phase_step;
 499         s32 fixp_i;
 500         s32 fixp_q;
 501
 502         /*
 503          * TODO: Generated beep tone goes very crackly when sample rate is
 504          * increased to ~1Msps or more. That is because of huge rounding error
 505          * of phase angle caused by used cosine implementation.
 506          */
 507
 508         /* calculate phase step */
 509         #define BEEP_FREQ 1000 /* 1kHz beep */
 510         src_phase_step = DIV_ROUND_CLOSEST(FIXP_2PI * BEEP_FREQ,
 511                         dev->sdr_adc_freq);
 512
 513         for (i = 0; i < plane_size; i += 2) {
 514                 mod_phase_step = fixp_cos32_rad(dev->sdr_fixp_src_phase,
 515                                                 FIXP_2PI) >> (31 - FIXP_N);
 516
 517                 dev->sdr_fixp_src_phase += src_phase_step;
 518                 dev->sdr_fixp_mod_phase += mod_phase_step / 4;
 519
 520                 /*
 521                  * Transfer phases to [0 / 2xPI] in order to avoid variable
 522                  * overflow and make it suitable for cosine implementation
 523                  * used, which does not support negative angles.
 524                  */
 525                 while (dev->sdr_fixp_mod_phase < FIXP_2PI)
 526                         dev->sdr_fixp_mod_phase += FIXP_2PI;
 527                 while (dev->sdr_fixp_mod_phase > FIXP_2PI)
 528                         dev->sdr_fixp_mod_phase -= FIXP_2PI;
 529
 530                 while (dev->sdr_fixp_src_phase > FIXP_2PI)
 531                         dev->sdr_fixp_src_phase -= FIXP_2PI;
 532
 533                 fixp_i = fixp_cos32_rad(dev->sdr_fixp_mod_phase, FIXP_2PI);
 534                 fixp_q = fixp_sin32_rad(dev->sdr_fixp_mod_phase, FIXP_2PI);
 535
 536                 /* Normalize fraction values represented with 32 bit precision
 537                  * to fixed point representation with FIXP_N bits */
 538                 fixp_i >>= (31 - FIXP_N);
 539                 fixp_q >>= (31 - FIXP_N);
 540
 541                 switch (dev->sdr_pixelformat) {
 542                 case V4L2_SDR_FMT_CU8:
 543                         /* convert 'fixp float' to u8 */
 544                         /* u8 = X * 127.5 + 127.5; X is float [-1.0, +1.0] */
 545                         fixp_i = fixp_i * 1275 + FIXP_FRAC * 1275;
 546                         fixp_q = fixp_q * 1275 + FIXP_FRAC * 1275;
 547                         *vbuf++ = DIV_ROUND_CLOSEST(fixp_i, FIXP_FRAC * 10);
 548                         *vbuf++ = DIV_ROUND_CLOSEST(fixp_q, FIXP_FRAC * 10);
 549                         break;
 550                 case V4L2_SDR_FMT_CS8:
 551                         /* convert 'fixp float' to s8 */
 552                         fixp_i = fixp_i * 1275;
 553                         fixp_q = fixp_q * 1275;
 554                         *vbuf++ = DIV_ROUND_CLOSEST(fixp_i, FIXP_FRAC * 10);
 555                         *vbuf++ = DIV_ROUND_CLOSEST(fixp_q, FIXP_FRAC * 10);
 556                         break;
 557                 default:
 558                         break;
 559                 }
 560         }
 561 }