1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * vivid-sdr-cap.c - software defined radio support functions.
4  *
5  * Copyright 2014 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
6  */
7 
8 #include <linux/errno.h>
9 #include <linux/kernel.h>
10 #include <linux/delay.h>
11 #include <linux/kthread.h>
12 #include <linux/freezer.h>
13 #include <linux/math64.h>
14 #include <linux/videodev2.h>
15 #include <linux/v4l2-dv-timings.h>
16 #include <media/v4l2-common.h>
17 #include <media/v4l2-event.h>
18 #include <media/v4l2-dv-timings.h>
19 #include <linux/fixp-arith.h>
20 #include <linux/jiffies.h>
21 
22 #include "vivid-core.h"
23 #include "vivid-ctrls.h"
24 #include "vivid-sdr-cap.h"
25 
26 /* stream formats */
27 struct vivid_format {
28 	u32	pixelformat;
29 	u32	buffersize;
30 };
31 
32 /* format descriptions for capture and preview */
33 static const struct vivid_format formats[] = {
34 	{
35 		.pixelformat	= V4L2_SDR_FMT_CU8,
36 		.buffersize	= SDR_CAP_SAMPLES_PER_BUF * 2,
37 	}, {
38 		.pixelformat	= V4L2_SDR_FMT_CS8,
39 		.buffersize	= SDR_CAP_SAMPLES_PER_BUF * 2,
40 	},
41 };
42 
43 static const struct v4l2_frequency_band bands_adc[] = {
44 	{
45 		.tuner = 0,
46 		.type = V4L2_TUNER_ADC,
47 		.index = 0,
48 		.capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
49 		.rangelow   =  300000,
50 		.rangehigh  =  300000,
51 	},
52 	{
53 		.tuner = 0,
54 		.type = V4L2_TUNER_ADC,
55 		.index = 1,
56 		.capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
57 		.rangelow   =  900001,
58 		.rangehigh  = 2800000,
59 	},
60 	{
61 		.tuner = 0,
62 		.type = V4L2_TUNER_ADC,
63 		.index = 2,
64 		.capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
65 		.rangelow   = 3200000,
66 		.rangehigh  = 3200000,
67 	},
68 };
69 
70 /* ADC band midpoints */
71 #define BAND_ADC_0 ((bands_adc[0].rangehigh + bands_adc[1].rangelow) / 2)
72 #define BAND_ADC_1 ((bands_adc[1].rangehigh + bands_adc[2].rangelow) / 2)
73 
74 static const struct v4l2_frequency_band bands_fm[] = {
75 	{
76 		.tuner = 1,
77 		.type = V4L2_TUNER_RF,
78 		.index = 0,
79 		.capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
80 		.rangelow   =    50000000,
81 		.rangehigh  =  2000000000,
82 	},
83 };
84 
vivid_thread_sdr_cap_tick(struct vivid_dev * dev)85 static void vivid_thread_sdr_cap_tick(struct vivid_dev *dev)
86 {
87 	struct vivid_buffer *sdr_cap_buf = NULL;
88 
89 	dprintk(dev, 1, "SDR Capture Thread Tick\n");
90 
91 	/* Drop a certain percentage of buffers. */
92 	if (dev->perc_dropped_buffers &&
93 	    get_random_u32_below(100) < dev->perc_dropped_buffers)
94 		return;
95 
96 	spin_lock(&dev->slock);
97 	if (!list_empty(&dev->sdr_cap_active)) {
98 		sdr_cap_buf = list_entry(dev->sdr_cap_active.next,
99 					 struct vivid_buffer, list);
100 		list_del(&sdr_cap_buf->list);
101 	}
102 	spin_unlock(&dev->slock);
103 
104 	if (sdr_cap_buf) {
105 		sdr_cap_buf->vb.sequence = dev->sdr_cap_with_seq_wrap_count;
106 		v4l2_ctrl_request_setup(sdr_cap_buf->vb.vb2_buf.req_obj.req,
107 					&dev->ctrl_hdl_sdr_cap);
108 		v4l2_ctrl_request_complete(sdr_cap_buf->vb.vb2_buf.req_obj.req,
109 					   &dev->ctrl_hdl_sdr_cap);
110 		vivid_sdr_cap_process(dev, sdr_cap_buf);
111 		sdr_cap_buf->vb.vb2_buf.timestamp =
112 			ktime_get_ns() + dev->time_wrap_offset;
113 		vb2_buffer_done(&sdr_cap_buf->vb.vb2_buf, dev->dqbuf_error ?
114 				VB2_BUF_STATE_ERROR : VB2_BUF_STATE_DONE);
115 		dev->dqbuf_error = false;
116 	}
117 }
118 
vivid_thread_sdr_cap(void * data)119 static int vivid_thread_sdr_cap(void *data)
120 {
121 	struct vivid_dev *dev = data;
122 	u64 samples_since_start;
123 	u64 buffers_since_start;
124 	u64 next_jiffies_since_start;
125 	unsigned long jiffies_since_start;
126 	unsigned long cur_jiffies;
127 	unsigned wait_jiffies;
128 
129 	dprintk(dev, 1, "SDR Capture Thread Start\n");
130 
131 	set_freezable();
132 
133 	/* Resets frame counters */
134 	dev->sdr_cap_seq_offset = 0;
135 	dev->sdr_cap_seq_count = 0;
136 	dev->jiffies_sdr_cap = jiffies;
137 	dev->sdr_cap_seq_resync = false;
138 	if (dev->time_wrap)
139 		dev->time_wrap_offset = dev->time_wrap - ktime_get_ns();
140 	else
141 		dev->time_wrap_offset = 0;
142 
143 	for (;;) {
144 		try_to_freeze();
145 		if (kthread_should_stop())
146 			break;
147 
148 		if (!mutex_trylock(&dev->mutex)) {
149 			schedule();
150 			continue;
151 		}
152 
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 		dev->sdr_cap_with_seq_wrap_count = dev->sdr_cap_seq_count - dev->sdr_cap_seq_start;
182 
183 		vivid_thread_sdr_cap_tick(dev);
184 		mutex_unlock(&dev->mutex);
185 
186 		/*
187 		 * Calculate the number of samples streamed since we started,
188 		 * not including the current buffer.
189 		 */
190 		samples_since_start = buffers_since_start * SDR_CAP_SAMPLES_PER_BUF;
191 
192 		/* And the number of jiffies since we started */
193 		jiffies_since_start = jiffies - dev->jiffies_sdr_cap;
194 
195 		/* Increase by the number of samples in one buffer */
196 		samples_since_start += SDR_CAP_SAMPLES_PER_BUF;
197 		/*
198 		 * Calculate when that next buffer is supposed to start
199 		 * in jiffies since we started streaming.
200 		 */
201 		next_jiffies_since_start = samples_since_start * HZ +
202 					   dev->sdr_adc_freq / 2;
203 		do_div(next_jiffies_since_start, dev->sdr_adc_freq);
204 		/* If it is in the past, then just schedule asap */
205 		if (next_jiffies_since_start < jiffies_since_start)
206 			next_jiffies_since_start = jiffies_since_start;
207 
208 		wait_jiffies = next_jiffies_since_start - jiffies_since_start;
209 		while (time_is_after_jiffies(cur_jiffies + wait_jiffies) &&
210 		       !kthread_should_stop())
211 			schedule();
212 	}
213 	dprintk(dev, 1, "SDR Capture Thread End\n");
214 	return 0;
215 }
216 
sdr_cap_queue_setup(struct vb2_queue * vq,unsigned * nbuffers,unsigned * nplanes,unsigned sizes[],struct device * alloc_devs[])217 static int sdr_cap_queue_setup(struct vb2_queue *vq,
218 		       unsigned *nbuffers, unsigned *nplanes,
219 		       unsigned sizes[], struct device *alloc_devs[])
220 {
221 	/* 2 = max 16-bit sample returned */
222 	sizes[0] = SDR_CAP_SAMPLES_PER_BUF * 2;
223 	*nplanes = 1;
224 	return 0;
225 }
226 
sdr_cap_buf_prepare(struct vb2_buffer * vb)227 static int sdr_cap_buf_prepare(struct vb2_buffer *vb)
228 {
229 	struct vivid_dev *dev = vb2_get_drv_priv(vb->vb2_queue);
230 	unsigned size = SDR_CAP_SAMPLES_PER_BUF * 2;
231 
232 	dprintk(dev, 1, "%s\n", __func__);
233 
234 	if (dev->buf_prepare_error) {
235 		/*
236 		 * Error injection: test what happens if buf_prepare() returns
237 		 * an error.
238 		 */
239 		dev->buf_prepare_error = false;
240 		return -EINVAL;
241 	}
242 	if (vb2_plane_size(vb, 0) < size) {
243 		dprintk(dev, 1, "%s data will not fit into plane (%lu < %u)\n",
244 				__func__, vb2_plane_size(vb, 0), size);
245 		return -EINVAL;
246 	}
247 	vb2_set_plane_payload(vb, 0, size);
248 
249 	return 0;
250 }
251 
sdr_cap_buf_queue(struct vb2_buffer * vb)252 static void sdr_cap_buf_queue(struct vb2_buffer *vb)
253 {
254 	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
255 	struct vivid_dev *dev = vb2_get_drv_priv(vb->vb2_queue);
256 	struct vivid_buffer *buf = container_of(vbuf, struct vivid_buffer, vb);
257 
258 	dprintk(dev, 1, "%s\n", __func__);
259 
260 	spin_lock(&dev->slock);
261 	list_add_tail(&buf->list, &dev->sdr_cap_active);
262 	spin_unlock(&dev->slock);
263 }
264 
sdr_cap_start_streaming(struct vb2_queue * vq,unsigned count)265 static int sdr_cap_start_streaming(struct vb2_queue *vq, unsigned count)
266 {
267 	struct vivid_dev *dev = vb2_get_drv_priv(vq);
268 	int err = 0;
269 
270 	dprintk(dev, 1, "%s\n", __func__);
271 	dev->sdr_cap_seq_start = dev->seq_wrap * 128;
272 	if (dev->start_streaming_error) {
273 		dev->start_streaming_error = false;
274 		err = -EINVAL;
275 	} else if (dev->kthread_sdr_cap == NULL) {
276 		dev->kthread_sdr_cap = kthread_run(vivid_thread_sdr_cap, dev,
277 				"%s-sdr-cap", dev->v4l2_dev.name);
278 
279 		if (IS_ERR(dev->kthread_sdr_cap)) {
280 			v4l2_err(&dev->v4l2_dev, "kernel_thread() failed\n");
281 			err = PTR_ERR(dev->kthread_sdr_cap);
282 			dev->kthread_sdr_cap = NULL;
283 		}
284 	}
285 	if (err) {
286 		struct vivid_buffer *buf, *tmp;
287 
288 		list_for_each_entry_safe(buf, tmp, &dev->sdr_cap_active, list) {
289 			list_del(&buf->list);
290 			vb2_buffer_done(&buf->vb.vb2_buf,
291 					VB2_BUF_STATE_QUEUED);
292 		}
293 	}
294 	return err;
295 }
296 
297 /* abort streaming and wait for last buffer */
sdr_cap_stop_streaming(struct vb2_queue * vq)298 static void sdr_cap_stop_streaming(struct vb2_queue *vq)
299 {
300 	struct vivid_dev *dev = vb2_get_drv_priv(vq);
301 
302 	if (dev->kthread_sdr_cap == NULL)
303 		return;
304 
305 	while (!list_empty(&dev->sdr_cap_active)) {
306 		struct vivid_buffer *buf;
307 
308 		buf = list_entry(dev->sdr_cap_active.next,
309 				struct vivid_buffer, list);
310 		list_del(&buf->list);
311 		v4l2_ctrl_request_complete(buf->vb.vb2_buf.req_obj.req,
312 					   &dev->ctrl_hdl_sdr_cap);
313 		vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
314 	}
315 
316 	/* shutdown control thread */
317 	kthread_stop(dev->kthread_sdr_cap);
318 	dev->kthread_sdr_cap = NULL;
319 }
320 
sdr_cap_buf_request_complete(struct vb2_buffer * vb)321 static void sdr_cap_buf_request_complete(struct vb2_buffer *vb)
322 {
323 	struct vivid_dev *dev = vb2_get_drv_priv(vb->vb2_queue);
324 
325 	v4l2_ctrl_request_complete(vb->req_obj.req, &dev->ctrl_hdl_sdr_cap);
326 }
327 
328 const struct vb2_ops vivid_sdr_cap_qops = {
329 	.queue_setup		= sdr_cap_queue_setup,
330 	.buf_prepare		= sdr_cap_buf_prepare,
331 	.buf_queue		= sdr_cap_buf_queue,
332 	.start_streaming	= sdr_cap_start_streaming,
333 	.stop_streaming		= sdr_cap_stop_streaming,
334 	.buf_request_complete	= sdr_cap_buf_request_complete,
335 	.wait_prepare		= vb2_ops_wait_prepare,
336 	.wait_finish		= vb2_ops_wait_finish,
337 };
338 
vivid_sdr_enum_freq_bands(struct file * file,void * fh,struct v4l2_frequency_band * band)339 int vivid_sdr_enum_freq_bands(struct file *file, void *fh,
340 		struct v4l2_frequency_band *band)
341 {
342 	switch (band->tuner) {
343 	case 0:
344 		if (band->index >= ARRAY_SIZE(bands_adc))
345 			return -EINVAL;
346 		*band = bands_adc[band->index];
347 		return 0;
348 	case 1:
349 		if (band->index >= ARRAY_SIZE(bands_fm))
350 			return -EINVAL;
351 		*band = bands_fm[band->index];
352 		return 0;
353 	default:
354 		return -EINVAL;
355 	}
356 }
357 
vivid_sdr_g_frequency(struct file * file,void * fh,struct v4l2_frequency * vf)358 int vivid_sdr_g_frequency(struct file *file, void *fh,
359 		struct v4l2_frequency *vf)
360 {
361 	struct vivid_dev *dev = video_drvdata(file);
362 
363 	switch (vf->tuner) {
364 	case 0:
365 		vf->frequency = dev->sdr_adc_freq;
366 		vf->type = V4L2_TUNER_ADC;
367 		return 0;
368 	case 1:
369 		vf->frequency = dev->sdr_fm_freq;
370 		vf->type = V4L2_TUNER_RF;
371 		return 0;
372 	default:
373 		return -EINVAL;
374 	}
375 }
376 
vivid_sdr_s_frequency(struct file * file,void * fh,const struct v4l2_frequency * vf)377 int vivid_sdr_s_frequency(struct file *file, void *fh,
378 		const struct v4l2_frequency *vf)
379 {
380 	struct vivid_dev *dev = video_drvdata(file);
381 	unsigned freq = vf->frequency;
382 	unsigned band;
383 
384 	switch (vf->tuner) {
385 	case 0:
386 		if (vf->type != V4L2_TUNER_ADC)
387 			return -EINVAL;
388 		if (freq < BAND_ADC_0)
389 			band = 0;
390 		else if (freq < BAND_ADC_1)
391 			band = 1;
392 		else
393 			band = 2;
394 
395 		freq = clamp_t(unsigned, freq,
396 				bands_adc[band].rangelow,
397 				bands_adc[band].rangehigh);
398 
399 		if (vb2_is_streaming(&dev->vb_sdr_cap_q) &&
400 		    freq != dev->sdr_adc_freq) {
401 			/* resync the thread's timings */
402 			dev->sdr_cap_seq_resync = true;
403 		}
404 		dev->sdr_adc_freq = freq;
405 		return 0;
406 	case 1:
407 		if (vf->type != V4L2_TUNER_RF)
408 			return -EINVAL;
409 		dev->sdr_fm_freq = clamp_t(unsigned, freq,
410 				bands_fm[0].rangelow,
411 				bands_fm[0].rangehigh);
412 		return 0;
413 	default:
414 		return -EINVAL;
415 	}
416 }
417 
vivid_sdr_g_tuner(struct file * file,void * fh,struct v4l2_tuner * vt)418 int vivid_sdr_g_tuner(struct file *file, void *fh, struct v4l2_tuner *vt)
419 {
420 	switch (vt->index) {
421 	case 0:
422 		strscpy(vt->name, "ADC", sizeof(vt->name));
423 		vt->type = V4L2_TUNER_ADC;
424 		vt->capability =
425 			V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS;
426 		vt->rangelow = bands_adc[0].rangelow;
427 		vt->rangehigh = bands_adc[2].rangehigh;
428 		return 0;
429 	case 1:
430 		strscpy(vt->name, "RF", sizeof(vt->name));
431 		vt->type = V4L2_TUNER_RF;
432 		vt->capability =
433 			V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS;
434 		vt->rangelow = bands_fm[0].rangelow;
435 		vt->rangehigh = bands_fm[0].rangehigh;
436 		return 0;
437 	default:
438 		return -EINVAL;
439 	}
440 }
441 
vivid_sdr_s_tuner(struct file * file,void * fh,const struct v4l2_tuner * vt)442 int vivid_sdr_s_tuner(struct file *file, void *fh, const struct v4l2_tuner *vt)
443 {
444 	if (vt->index > 1)
445 		return -EINVAL;
446 	return 0;
447 }
448 
vidioc_enum_fmt_sdr_cap(struct file * file,void * fh,struct v4l2_fmtdesc * f)449 int vidioc_enum_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_fmtdesc *f)
450 {
451 	if (f->index >= ARRAY_SIZE(formats))
452 		return -EINVAL;
453 	f->pixelformat = formats[f->index].pixelformat;
454 	return 0;
455 }
456 
vidioc_g_fmt_sdr_cap(struct file * file,void * fh,struct v4l2_format * f)457 int vidioc_g_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_format *f)
458 {
459 	struct vivid_dev *dev = video_drvdata(file);
460 
461 	f->fmt.sdr.pixelformat = dev->sdr_pixelformat;
462 	f->fmt.sdr.buffersize = dev->sdr_buffersize;
463 	return 0;
464 }
465 
vidioc_s_fmt_sdr_cap(struct file * file,void * fh,struct v4l2_format * f)466 int vidioc_s_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_format *f)
467 {
468 	struct vivid_dev *dev = video_drvdata(file);
469 	struct vb2_queue *q = &dev->vb_sdr_cap_q;
470 	int i;
471 
472 	if (vb2_is_busy(q))
473 		return -EBUSY;
474 
475 	for (i = 0; i < ARRAY_SIZE(formats); i++) {
476 		if (formats[i].pixelformat == f->fmt.sdr.pixelformat) {
477 			dev->sdr_pixelformat = formats[i].pixelformat;
478 			dev->sdr_buffersize = formats[i].buffersize;
479 			f->fmt.sdr.buffersize = formats[i].buffersize;
480 			return 0;
481 		}
482 	}
483 	dev->sdr_pixelformat = formats[0].pixelformat;
484 	dev->sdr_buffersize = formats[0].buffersize;
485 	f->fmt.sdr.pixelformat = formats[0].pixelformat;
486 	f->fmt.sdr.buffersize = formats[0].buffersize;
487 	return 0;
488 }
489 
vidioc_try_fmt_sdr_cap(struct file * file,void * fh,struct v4l2_format * f)490 int vidioc_try_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_format *f)
491 {
492 	int i;
493 
494 	for (i = 0; i < ARRAY_SIZE(formats); i++) {
495 		if (formats[i].pixelformat == f->fmt.sdr.pixelformat) {
496 			f->fmt.sdr.buffersize = formats[i].buffersize;
497 			return 0;
498 		}
499 	}
500 	f->fmt.sdr.pixelformat = formats[0].pixelformat;
501 	f->fmt.sdr.buffersize = formats[0].buffersize;
502 	return 0;
503 }
504 
505 #define FIXP_N    (15)
506 #define FIXP_FRAC (1 << FIXP_N)
507 #define FIXP_2PI  ((int)(2 * 3.141592653589 * FIXP_FRAC))
508 #define M_100000PI (3.14159 * 100000)
509 
vivid_sdr_cap_process(struct vivid_dev * dev,struct vivid_buffer * buf)510 void vivid_sdr_cap_process(struct vivid_dev *dev, struct vivid_buffer *buf)
511 {
512 	u8 *vbuf = vb2_plane_vaddr(&buf->vb.vb2_buf, 0);
513 	unsigned long i;
514 	unsigned long plane_size = vb2_plane_size(&buf->vb.vb2_buf, 0);
515 	s64 s64tmp;
516 	s32 src_phase_step;
517 	s32 mod_phase_step;
518 	s32 fixp_i;
519 	s32 fixp_q;
520 
521 	/* calculate phase step */
522 	#define BEEP_FREQ 1000 /* 1kHz beep */
523 	src_phase_step = DIV_ROUND_CLOSEST(FIXP_2PI * BEEP_FREQ,
524 					   dev->sdr_adc_freq);
525 
526 	for (i = 0; i < plane_size; i += 2) {
527 		mod_phase_step = fixp_cos32_rad(dev->sdr_fixp_src_phase,
528 						FIXP_2PI) >> (31 - FIXP_N);
529 
530 		dev->sdr_fixp_src_phase += src_phase_step;
531 		s64tmp = (s64) mod_phase_step * dev->sdr_fm_deviation;
532 		dev->sdr_fixp_mod_phase += div_s64(s64tmp, M_100000PI);
533 
534 		/*
535 		 * Transfer phase angle to [0, 2xPI] in order to avoid variable
536 		 * overflow and make it suitable for cosine implementation
537 		 * used, which does not support negative angles.
538 		 */
539 		dev->sdr_fixp_src_phase %= FIXP_2PI;
540 		dev->sdr_fixp_mod_phase %= FIXP_2PI;
541 
542 		if (dev->sdr_fixp_mod_phase < 0)
543 			dev->sdr_fixp_mod_phase += FIXP_2PI;
544 
545 		fixp_i = fixp_cos32_rad(dev->sdr_fixp_mod_phase, FIXP_2PI);
546 		fixp_q = fixp_sin32_rad(dev->sdr_fixp_mod_phase, FIXP_2PI);
547 
548 		/* Normalize fraction values represented with 32 bit precision
549 		 * to fixed point representation with FIXP_N bits */
550 		fixp_i >>= (31 - FIXP_N);
551 		fixp_q >>= (31 - FIXP_N);
552 
553 		switch (dev->sdr_pixelformat) {
554 		case V4L2_SDR_FMT_CU8:
555 			/* convert 'fixp float' to u8 [0, +255] */
556 			/* u8 = X * 127.5 + 127.5; X is float [-1.0, +1.0] */
557 			fixp_i = fixp_i * 1275 + FIXP_FRAC * 1275;
558 			fixp_q = fixp_q * 1275 + FIXP_FRAC * 1275;
559 			*vbuf++ = DIV_ROUND_CLOSEST(fixp_i, FIXP_FRAC * 10);
560 			*vbuf++ = DIV_ROUND_CLOSEST(fixp_q, FIXP_FRAC * 10);
561 			break;
562 		case V4L2_SDR_FMT_CS8:
563 			/* convert 'fixp float' to s8 [-128, +127] */
564 			/* s8 = X * 127.5 - 0.5; X is float [-1.0, +1.0] */
565 			fixp_i = fixp_i * 1275 - FIXP_FRAC * 5;
566 			fixp_q = fixp_q * 1275 - FIXP_FRAC * 5;
567 			*vbuf++ = DIV_ROUND_CLOSEST(fixp_i, FIXP_FRAC * 10);
568 			*vbuf++ = DIV_ROUND_CLOSEST(fixp_q, FIXP_FRAC * 10);
569 			break;
570 		default:
571 			break;
572 		}
573 	}
574 }
575