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