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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 
vivid_thread_sdr_cap_tick(struct vivid_dev * dev)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 		v4l2_get_timestamp(&sdr_cap_buf->vb.timestamp);
121 		sdr_cap_buf->vb.timestamp.tv_sec += 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 
vivid_thread_sdr_cap(void * data)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 		if (!mutex_trylock(&dev->mutex)) {
155 			schedule_timeout_uninterruptible(1);
156 			continue;
157 		}
158 
159 		cur_jiffies = jiffies;
160 		if (dev->sdr_cap_seq_resync) {
161 			dev->jiffies_sdr_cap = cur_jiffies;
162 			dev->sdr_cap_seq_offset = dev->sdr_cap_seq_count + 1;
163 			dev->sdr_cap_seq_count = 0;
164 			dev->sdr_cap_seq_resync = false;
165 		}
166 		/* Calculate the number of jiffies since we started streaming */
167 		jiffies_since_start = cur_jiffies - dev->jiffies_sdr_cap;
168 		/* Get the number of buffers streamed since the start */
169 		buffers_since_start =
170 			(u64)jiffies_since_start * dev->sdr_adc_freq +
171 				      (HZ * SDR_CAP_SAMPLES_PER_BUF) / 2;
172 		do_div(buffers_since_start, HZ * SDR_CAP_SAMPLES_PER_BUF);
173 
174 		/*
175 		 * After more than 0xf0000000 (rounded down to a multiple of
176 		 * 'jiffies-per-day' to ease jiffies_to_msecs calculation)
177 		 * jiffies have passed since we started streaming reset the
178 		 * counters and keep track of the sequence offset.
179 		 */
180 		if (jiffies_since_start > JIFFIES_RESYNC) {
181 			dev->jiffies_sdr_cap = cur_jiffies;
182 			dev->sdr_cap_seq_offset = buffers_since_start;
183 			buffers_since_start = 0;
184 		}
185 		dev->sdr_cap_seq_count =
186 			buffers_since_start + dev->sdr_cap_seq_offset;
187 
188 		vivid_thread_sdr_cap_tick(dev);
189 		mutex_unlock(&dev->mutex);
190 
191 		/*
192 		 * Calculate the number of samples streamed since we started,
193 		 * not including the current buffer.
194 		 */
195 		samples_since_start = buffers_since_start * SDR_CAP_SAMPLES_PER_BUF;
196 
197 		/* And the number of jiffies since we started */
198 		jiffies_since_start = jiffies - dev->jiffies_sdr_cap;
199 
200 		/* Increase by the number of samples in one buffer */
201 		samples_since_start += SDR_CAP_SAMPLES_PER_BUF;
202 		/*
203 		 * Calculate when that next buffer is supposed to start
204 		 * in jiffies since we started streaming.
205 		 */
206 		next_jiffies_since_start = samples_since_start * HZ +
207 					   dev->sdr_adc_freq / 2;
208 		do_div(next_jiffies_since_start, dev->sdr_adc_freq);
209 		/* If it is in the past, then just schedule asap */
210 		if (next_jiffies_since_start < jiffies_since_start)
211 			next_jiffies_since_start = jiffies_since_start;
212 
213 		wait_jiffies = next_jiffies_since_start - jiffies_since_start;
214 		schedule_timeout_interruptible(wait_jiffies ? wait_jiffies : 1);
215 	}
216 	dprintk(dev, 1, "SDR Capture Thread End\n");
217 	return 0;
218 }
219 
sdr_cap_queue_setup(struct vb2_queue * vq,const void * parg,unsigned * nbuffers,unsigned * nplanes,unsigned sizes[],void * alloc_ctxs[])220 static int sdr_cap_queue_setup(struct vb2_queue *vq, const void *parg,
221 		       unsigned *nbuffers, unsigned *nplanes,
222 		       unsigned sizes[], void *alloc_ctxs[])
223 {
224 	/* 2 = max 16-bit sample returned */
225 	sizes[0] = SDR_CAP_SAMPLES_PER_BUF * 2;
226 	*nplanes = 1;
227 	return 0;
228 }
229 
sdr_cap_buf_prepare(struct vb2_buffer * vb)230 static int sdr_cap_buf_prepare(struct vb2_buffer *vb)
231 {
232 	struct vivid_dev *dev = vb2_get_drv_priv(vb->vb2_queue);
233 	unsigned size = SDR_CAP_SAMPLES_PER_BUF * 2;
234 
235 	dprintk(dev, 1, "%s\n", __func__);
236 
237 	if (dev->buf_prepare_error) {
238 		/*
239 		 * Error injection: test what happens if buf_prepare() returns
240 		 * an error.
241 		 */
242 		dev->buf_prepare_error = false;
243 		return -EINVAL;
244 	}
245 	if (vb2_plane_size(vb, 0) < size) {
246 		dprintk(dev, 1, "%s data will not fit into plane (%lu < %u)\n",
247 				__func__, vb2_plane_size(vb, 0), size);
248 		return -EINVAL;
249 	}
250 	vb2_set_plane_payload(vb, 0, size);
251 
252 	return 0;
253 }
254 
sdr_cap_buf_queue(struct vb2_buffer * vb)255 static void sdr_cap_buf_queue(struct vb2_buffer *vb)
256 {
257 	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
258 	struct vivid_dev *dev = vb2_get_drv_priv(vb->vb2_queue);
259 	struct vivid_buffer *buf = container_of(vbuf, struct vivid_buffer, vb);
260 
261 	dprintk(dev, 1, "%s\n", __func__);
262 
263 	spin_lock(&dev->slock);
264 	list_add_tail(&buf->list, &dev->sdr_cap_active);
265 	spin_unlock(&dev->slock);
266 }
267 
sdr_cap_start_streaming(struct vb2_queue * vq,unsigned count)268 static int sdr_cap_start_streaming(struct vb2_queue *vq, unsigned count)
269 {
270 	struct vivid_dev *dev = vb2_get_drv_priv(vq);
271 	int err = 0;
272 
273 	dprintk(dev, 1, "%s\n", __func__);
274 	dev->sdr_cap_seq_count = 0;
275 	if (dev->start_streaming_error) {
276 		dev->start_streaming_error = false;
277 		err = -EINVAL;
278 	} else if (dev->kthread_sdr_cap == NULL) {
279 		dev->kthread_sdr_cap = kthread_run(vivid_thread_sdr_cap, dev,
280 				"%s-sdr-cap", dev->v4l2_dev.name);
281 
282 		if (IS_ERR(dev->kthread_sdr_cap)) {
283 			v4l2_err(&dev->v4l2_dev, "kernel_thread() failed\n");
284 			err = PTR_ERR(dev->kthread_sdr_cap);
285 			dev->kthread_sdr_cap = NULL;
286 		}
287 	}
288 	if (err) {
289 		struct vivid_buffer *buf, *tmp;
290 
291 		list_for_each_entry_safe(buf, tmp, &dev->sdr_cap_active, list) {
292 			list_del(&buf->list);
293 			vb2_buffer_done(&buf->vb.vb2_buf,
294 					VB2_BUF_STATE_QUEUED);
295 		}
296 	}
297 	return err;
298 }
299 
300 /* abort streaming and wait for last buffer */
sdr_cap_stop_streaming(struct vb2_queue * vq)301 static void sdr_cap_stop_streaming(struct vb2_queue *vq)
302 {
303 	struct vivid_dev *dev = vb2_get_drv_priv(vq);
304 
305 	if (dev->kthread_sdr_cap == NULL)
306 		return;
307 
308 	while (!list_empty(&dev->sdr_cap_active)) {
309 		struct vivid_buffer *buf;
310 
311 		buf = list_entry(dev->sdr_cap_active.next,
312 				struct vivid_buffer, list);
313 		list_del(&buf->list);
314 		vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
315 	}
316 
317 	/* shutdown control thread */
318 	kthread_stop(dev->kthread_sdr_cap);
319 	dev->kthread_sdr_cap = NULL;
320 }
321 
322 const struct vb2_ops vivid_sdr_cap_qops = {
323 	.queue_setup		= sdr_cap_queue_setup,
324 	.buf_prepare		= sdr_cap_buf_prepare,
325 	.buf_queue		= sdr_cap_buf_queue,
326 	.start_streaming	= sdr_cap_start_streaming,
327 	.stop_streaming		= sdr_cap_stop_streaming,
328 	.wait_prepare		= vb2_ops_wait_prepare,
329 	.wait_finish		= vb2_ops_wait_finish,
330 };
331 
vivid_sdr_enum_freq_bands(struct file * file,void * fh,struct v4l2_frequency_band * band)332 int vivid_sdr_enum_freq_bands(struct file *file, void *fh,
333 		struct v4l2_frequency_band *band)
334 {
335 	switch (band->tuner) {
336 	case 0:
337 		if (band->index >= ARRAY_SIZE(bands_adc))
338 			return -EINVAL;
339 		*band = bands_adc[band->index];
340 		return 0;
341 	case 1:
342 		if (band->index >= ARRAY_SIZE(bands_fm))
343 			return -EINVAL;
344 		*band = bands_fm[band->index];
345 		return 0;
346 	default:
347 		return -EINVAL;
348 	}
349 }
350 
vivid_sdr_g_frequency(struct file * file,void * fh,struct v4l2_frequency * vf)351 int vivid_sdr_g_frequency(struct file *file, void *fh,
352 		struct v4l2_frequency *vf)
353 {
354 	struct vivid_dev *dev = video_drvdata(file);
355 
356 	switch (vf->tuner) {
357 	case 0:
358 		vf->frequency = dev->sdr_adc_freq;
359 		vf->type = V4L2_TUNER_ADC;
360 		return 0;
361 	case 1:
362 		vf->frequency = dev->sdr_fm_freq;
363 		vf->type = V4L2_TUNER_RF;
364 		return 0;
365 	default:
366 		return -EINVAL;
367 	}
368 }
369 
vivid_sdr_s_frequency(struct file * file,void * fh,const struct v4l2_frequency * vf)370 int vivid_sdr_s_frequency(struct file *file, void *fh,
371 		const struct v4l2_frequency *vf)
372 {
373 	struct vivid_dev *dev = video_drvdata(file);
374 	unsigned freq = vf->frequency;
375 	unsigned band;
376 
377 	switch (vf->tuner) {
378 	case 0:
379 		if (vf->type != V4L2_TUNER_ADC)
380 			return -EINVAL;
381 		if (freq < BAND_ADC_0)
382 			band = 0;
383 		else if (freq < BAND_ADC_1)
384 			band = 1;
385 		else
386 			band = 2;
387 
388 		freq = clamp_t(unsigned, freq,
389 				bands_adc[band].rangelow,
390 				bands_adc[band].rangehigh);
391 
392 		if (vb2_is_streaming(&dev->vb_sdr_cap_q) &&
393 		    freq != dev->sdr_adc_freq) {
394 			/* resync the thread's timings */
395 			dev->sdr_cap_seq_resync = true;
396 		}
397 		dev->sdr_adc_freq = freq;
398 		return 0;
399 	case 1:
400 		if (vf->type != V4L2_TUNER_RF)
401 			return -EINVAL;
402 		dev->sdr_fm_freq = clamp_t(unsigned, freq,
403 				bands_fm[0].rangelow,
404 				bands_fm[0].rangehigh);
405 		return 0;
406 	default:
407 		return -EINVAL;
408 	}
409 }
410 
vivid_sdr_g_tuner(struct file * file,void * fh,struct v4l2_tuner * vt)411 int vivid_sdr_g_tuner(struct file *file, void *fh, struct v4l2_tuner *vt)
412 {
413 	switch (vt->index) {
414 	case 0:
415 		strlcpy(vt->name, "ADC", sizeof(vt->name));
416 		vt->type = V4L2_TUNER_ADC;
417 		vt->capability =
418 			V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS;
419 		vt->rangelow = bands_adc[0].rangelow;
420 		vt->rangehigh = bands_adc[2].rangehigh;
421 		return 0;
422 	case 1:
423 		strlcpy(vt->name, "RF", sizeof(vt->name));
424 		vt->type = V4L2_TUNER_RF;
425 		vt->capability =
426 			V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS;
427 		vt->rangelow = bands_fm[0].rangelow;
428 		vt->rangehigh = bands_fm[0].rangehigh;
429 		return 0;
430 	default:
431 		return -EINVAL;
432 	}
433 }
434 
vivid_sdr_s_tuner(struct file * file,void * fh,const struct v4l2_tuner * vt)435 int vivid_sdr_s_tuner(struct file *file, void *fh, const struct v4l2_tuner *vt)
436 {
437 	if (vt->index > 1)
438 		return -EINVAL;
439 	return 0;
440 }
441 
vidioc_enum_fmt_sdr_cap(struct file * file,void * fh,struct v4l2_fmtdesc * f)442 int vidioc_enum_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_fmtdesc *f)
443 {
444 	if (f->index >= ARRAY_SIZE(formats))
445 		return -EINVAL;
446 	f->pixelformat = formats[f->index].pixelformat;
447 	return 0;
448 }
449 
vidioc_g_fmt_sdr_cap(struct file * file,void * fh,struct v4l2_format * f)450 int vidioc_g_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_format *f)
451 {
452 	struct vivid_dev *dev = video_drvdata(file);
453 
454 	f->fmt.sdr.pixelformat = dev->sdr_pixelformat;
455 	f->fmt.sdr.buffersize = dev->sdr_buffersize;
456 	memset(f->fmt.sdr.reserved, 0, sizeof(f->fmt.sdr.reserved));
457 	return 0;
458 }
459 
vidioc_s_fmt_sdr_cap(struct file * file,void * fh,struct v4l2_format * f)460 int vidioc_s_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_format *f)
461 {
462 	struct vivid_dev *dev = video_drvdata(file);
463 	struct vb2_queue *q = &dev->vb_sdr_cap_q;
464 	int i;
465 
466 	if (vb2_is_busy(q))
467 		return -EBUSY;
468 
469 	memset(f->fmt.sdr.reserved, 0, sizeof(f->fmt.sdr.reserved));
470 	for (i = 0; i < ARRAY_SIZE(formats); i++) {
471 		if (formats[i].pixelformat == f->fmt.sdr.pixelformat) {
472 			dev->sdr_pixelformat = formats[i].pixelformat;
473 			dev->sdr_buffersize = formats[i].buffersize;
474 			f->fmt.sdr.buffersize = formats[i].buffersize;
475 			return 0;
476 		}
477 	}
478 	dev->sdr_pixelformat = formats[0].pixelformat;
479 	dev->sdr_buffersize = formats[0].buffersize;
480 	f->fmt.sdr.pixelformat = formats[0].pixelformat;
481 	f->fmt.sdr.buffersize = formats[0].buffersize;
482 	return 0;
483 }
484 
vidioc_try_fmt_sdr_cap(struct file * file,void * fh,struct v4l2_format * f)485 int vidioc_try_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_format *f)
486 {
487 	int i;
488 
489 	memset(f->fmt.sdr.reserved, 0, sizeof(f->fmt.sdr.reserved));
490 	for (i = 0; i < ARRAY_SIZE(formats); i++) {
491 		if (formats[i].pixelformat == f->fmt.sdr.pixelformat) {
492 			f->fmt.sdr.buffersize = formats[i].buffersize;
493 			return 0;
494 		}
495 	}
496 	f->fmt.sdr.pixelformat = formats[0].pixelformat;
497 	f->fmt.sdr.buffersize = formats[0].buffersize;
498 	return 0;
499 }
500 
501 #define FIXP_N    (15)
502 #define FIXP_FRAC (1 << FIXP_N)
503 #define FIXP_2PI  ((int)(2 * 3.141592653589 * FIXP_FRAC))
504 #define M_100000PI (3.14159 * 100000)
505 
vivid_sdr_cap_process(struct vivid_dev * dev,struct vivid_buffer * buf)506 void vivid_sdr_cap_process(struct vivid_dev *dev, struct vivid_buffer *buf)
507 {
508 	u8 *vbuf = vb2_plane_vaddr(&buf->vb.vb2_buf, 0);
509 	unsigned long i;
510 	unsigned long plane_size = vb2_plane_size(&buf->vb.vb2_buf, 0);
511 	s64 s64tmp;
512 	s32 src_phase_step;
513 	s32 mod_phase_step;
514 	s32 fixp_i;
515 	s32 fixp_q;
516 
517 	/* calculate phase step */
518 	#define BEEP_FREQ 1000 /* 1kHz beep */
519 	src_phase_step = DIV_ROUND_CLOSEST(FIXP_2PI * BEEP_FREQ,
520 					   dev->sdr_adc_freq);
521 
522 	for (i = 0; i < plane_size; i += 2) {
523 		mod_phase_step = fixp_cos32_rad(dev->sdr_fixp_src_phase,
524 						FIXP_2PI) >> (31 - FIXP_N);
525 
526 		dev->sdr_fixp_src_phase += src_phase_step;
527 		s64tmp = (s64) mod_phase_step * dev->sdr_fm_deviation;
528 		dev->sdr_fixp_mod_phase += div_s64(s64tmp, M_100000PI);
529 
530 		/*
531 		 * Transfer phase angle to [0, 2xPI] in order to avoid variable
532 		 * overflow and make it suitable for cosine implementation
533 		 * used, which does not support negative angles.
534 		 */
535 		dev->sdr_fixp_src_phase %= FIXP_2PI;
536 		dev->sdr_fixp_mod_phase %= FIXP_2PI;
537 
538 		if (dev->sdr_fixp_mod_phase < 0)
539 			dev->sdr_fixp_mod_phase += FIXP_2PI;
540 
541 		fixp_i = fixp_cos32_rad(dev->sdr_fixp_mod_phase, FIXP_2PI);
542 		fixp_q = fixp_sin32_rad(dev->sdr_fixp_mod_phase, FIXP_2PI);
543 
544 		/* Normalize fraction values represented with 32 bit precision
545 		 * to fixed point representation with FIXP_N bits */
546 		fixp_i >>= (31 - FIXP_N);
547 		fixp_q >>= (31 - FIXP_N);
548 
549 		switch (dev->sdr_pixelformat) {
550 		case V4L2_SDR_FMT_CU8:
551 			/* convert 'fixp float' to u8 [0, +255] */
552 			/* u8 = X * 127.5 + 127.5; X is float [-1.0, +1.0] */
553 			fixp_i = fixp_i * 1275 + FIXP_FRAC * 1275;
554 			fixp_q = fixp_q * 1275 + FIXP_FRAC * 1275;
555 			*vbuf++ = DIV_ROUND_CLOSEST(fixp_i, FIXP_FRAC * 10);
556 			*vbuf++ = DIV_ROUND_CLOSEST(fixp_q, FIXP_FRAC * 10);
557 			break;
558 		case V4L2_SDR_FMT_CS8:
559 			/* convert 'fixp float' to s8 [-128, +127] */
560 			/* s8 = X * 127.5 - 0.5; X is float [-1.0, +1.0] */
561 			fixp_i = fixp_i * 1275 - FIXP_FRAC * 5;
562 			fixp_q = fixp_q * 1275 - FIXP_FRAC * 5;
563 			*vbuf++ = DIV_ROUND_CLOSEST(fixp_i, FIXP_FRAC * 10);
564 			*vbuf++ = DIV_ROUND_CLOSEST(fixp_q, FIXP_FRAC * 10);
565 			break;
566 		default:
567 			break;
568 		}
569 	}
570 }
571