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 
21 #include "vivid-core.h"
22 #include "vivid-ctrls.h"
23 #include "vivid-sdr-cap.h"
24 
25 /* stream formats */
26 struct vivid_format {
27 	u32	pixelformat;
28 	u32	buffersize;
29 };
30 
31 /* format descriptions for capture and preview */
32 static const struct vivid_format formats[] = {
33 	{
34 		.pixelformat	= V4L2_SDR_FMT_CU8,
35 		.buffersize	= SDR_CAP_SAMPLES_PER_BUF * 2,
36 	}, {
37 		.pixelformat	= V4L2_SDR_FMT_CS8,
38 		.buffersize	= SDR_CAP_SAMPLES_PER_BUF * 2,
39 	},
40 };
41 
42 static const struct v4l2_frequency_band bands_adc[] = {
43 	{
44 		.tuner = 0,
45 		.type = V4L2_TUNER_ADC,
46 		.index = 0,
47 		.capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
48 		.rangelow   =  300000,
49 		.rangehigh  =  300000,
50 	},
51 	{
52 		.tuner = 0,
53 		.type = V4L2_TUNER_ADC,
54 		.index = 1,
55 		.capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
56 		.rangelow   =  900001,
57 		.rangehigh  = 2800000,
58 	},
59 	{
60 		.tuner = 0,
61 		.type = V4L2_TUNER_ADC,
62 		.index = 2,
63 		.capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
64 		.rangelow   = 3200000,
65 		.rangehigh  = 3200000,
66 	},
67 };
68 
69 /* ADC band midpoints */
70 #define BAND_ADC_0 ((bands_adc[0].rangehigh + bands_adc[1].rangelow) / 2)
71 #define BAND_ADC_1 ((bands_adc[1].rangehigh + bands_adc[2].rangelow) / 2)
72 
73 static const struct v4l2_frequency_band bands_fm[] = {
74 	{
75 		.tuner = 1,
76 		.type = V4L2_TUNER_RF,
77 		.index = 0,
78 		.capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
79 		.rangelow   =    50000000,
80 		.rangehigh  =  2000000000,
81 	},
82 };
83 
vivid_thread_sdr_cap_tick(struct vivid_dev * dev)84 static void vivid_thread_sdr_cap_tick(struct vivid_dev *dev)
85 {
86 	struct vivid_buffer *sdr_cap_buf = NULL;
87 
88 	dprintk(dev, 1, "SDR Capture Thread Tick\n");
89 
90 	/* Drop a certain percentage of buffers. */
91 	if (dev->perc_dropped_buffers &&
92 	    prandom_u32_max(100) < dev->perc_dropped_buffers)
93 		return;
94 
95 	spin_lock(&dev->slock);
96 	if (!list_empty(&dev->sdr_cap_active)) {
97 		sdr_cap_buf = list_entry(dev->sdr_cap_active.next,
98 					 struct vivid_buffer, list);
99 		list_del(&sdr_cap_buf->list);
100 	}
101 	spin_unlock(&dev->slock);
102 
103 	if (sdr_cap_buf) {
104 		sdr_cap_buf->vb.sequence = dev->sdr_cap_seq_count;
105 		v4l2_ctrl_request_setup(sdr_cap_buf->vb.vb2_buf.req_obj.req,
106 					&dev->ctrl_hdl_sdr_cap);
107 		v4l2_ctrl_request_complete(sdr_cap_buf->vb.vb2_buf.req_obj.req,
108 					   &dev->ctrl_hdl_sdr_cap);
109 		vivid_sdr_cap_process(dev, sdr_cap_buf);
110 		sdr_cap_buf->vb.vb2_buf.timestamp =
111 			ktime_get_ns() + dev->time_wrap_offset;
112 		vb2_buffer_done(&sdr_cap_buf->vb.vb2_buf, dev->dqbuf_error ?
113 				VB2_BUF_STATE_ERROR : VB2_BUF_STATE_DONE);
114 		dev->dqbuf_error = false;
115 	}
116 }
117 
vivid_thread_sdr_cap(void * data)118 static int vivid_thread_sdr_cap(void *data)
119 {
120 	struct vivid_dev *dev = data;
121 	u64 samples_since_start;
122 	u64 buffers_since_start;
123 	u64 next_jiffies_since_start;
124 	unsigned long jiffies_since_start;
125 	unsigned long cur_jiffies;
126 	unsigned wait_jiffies;
127 
128 	dprintk(dev, 1, "SDR Capture Thread Start\n");
129 
130 	set_freezable();
131 
132 	/* Resets frame counters */
133 	dev->sdr_cap_seq_offset = 0;
134 	if (dev->seq_wrap)
135 		dev->sdr_cap_seq_offset = 0xffffff80U;
136 	dev->jiffies_sdr_cap = jiffies;
137 	dev->sdr_cap_seq_resync = false;
138 
139 	for (;;) {
140 		try_to_freeze();
141 		if (kthread_should_stop())
142 			break;
143 
144 		mutex_lock(&dev->mutex);
145 		cur_jiffies = jiffies;
146 		if (dev->sdr_cap_seq_resync) {
147 			dev->jiffies_sdr_cap = cur_jiffies;
148 			dev->sdr_cap_seq_offset = dev->sdr_cap_seq_count + 1;
149 			dev->sdr_cap_seq_count = 0;
150 			dev->sdr_cap_seq_resync = false;
151 		}
152 		/* Calculate the number of jiffies since we started streaming */
153 		jiffies_since_start = cur_jiffies - dev->jiffies_sdr_cap;
154 		/* Get the number of buffers streamed since the start */
155 		buffers_since_start =
156 			(u64)jiffies_since_start * dev->sdr_adc_freq +
157 				      (HZ * SDR_CAP_SAMPLES_PER_BUF) / 2;
158 		do_div(buffers_since_start, HZ * SDR_CAP_SAMPLES_PER_BUF);
159 
160 		/*
161 		 * After more than 0xf0000000 (rounded down to a multiple of
162 		 * 'jiffies-per-day' to ease jiffies_to_msecs calculation)
163 		 * jiffies have passed since we started streaming reset the
164 		 * counters and keep track of the sequence offset.
165 		 */
166 		if (jiffies_since_start > JIFFIES_RESYNC) {
167 			dev->jiffies_sdr_cap = cur_jiffies;
168 			dev->sdr_cap_seq_offset = buffers_since_start;
169 			buffers_since_start = 0;
170 		}
171 		dev->sdr_cap_seq_count =
172 			buffers_since_start + dev->sdr_cap_seq_offset;
173 
174 		vivid_thread_sdr_cap_tick(dev);
175 		mutex_unlock(&dev->mutex);
176 
177 		/*
178 		 * Calculate the number of samples streamed since we started,
179 		 * not including the current buffer.
180 		 */
181 		samples_since_start = buffers_since_start * SDR_CAP_SAMPLES_PER_BUF;
182 
183 		/* And the number of jiffies since we started */
184 		jiffies_since_start = jiffies - dev->jiffies_sdr_cap;
185 
186 		/* Increase by the number of samples in one buffer */
187 		samples_since_start += SDR_CAP_SAMPLES_PER_BUF;
188 		/*
189 		 * Calculate when that next buffer is supposed to start
190 		 * in jiffies since we started streaming.
191 		 */
192 		next_jiffies_since_start = samples_since_start * HZ +
193 					   dev->sdr_adc_freq / 2;
194 		do_div(next_jiffies_since_start, dev->sdr_adc_freq);
195 		/* If it is in the past, then just schedule asap */
196 		if (next_jiffies_since_start < jiffies_since_start)
197 			next_jiffies_since_start = jiffies_since_start;
198 
199 		wait_jiffies = next_jiffies_since_start - jiffies_since_start;
200 		schedule_timeout_interruptible(wait_jiffies ? wait_jiffies : 1);
201 	}
202 	dprintk(dev, 1, "SDR Capture Thread End\n");
203 	return 0;
204 }
205 
sdr_cap_queue_setup(struct vb2_queue * vq,unsigned * nbuffers,unsigned * nplanes,unsigned sizes[],struct device * alloc_devs[])206 static int sdr_cap_queue_setup(struct vb2_queue *vq,
207 		       unsigned *nbuffers, unsigned *nplanes,
208 		       unsigned sizes[], struct device *alloc_devs[])
209 {
210 	/* 2 = max 16-bit sample returned */
211 	sizes[0] = SDR_CAP_SAMPLES_PER_BUF * 2;
212 	*nplanes = 1;
213 	return 0;
214 }
215 
sdr_cap_buf_prepare(struct vb2_buffer * vb)216 static int sdr_cap_buf_prepare(struct vb2_buffer *vb)
217 {
218 	struct vivid_dev *dev = vb2_get_drv_priv(vb->vb2_queue);
219 	unsigned size = SDR_CAP_SAMPLES_PER_BUF * 2;
220 
221 	dprintk(dev, 1, "%s\n", __func__);
222 
223 	if (dev->buf_prepare_error) {
224 		/*
225 		 * Error injection: test what happens if buf_prepare() returns
226 		 * an error.
227 		 */
228 		dev->buf_prepare_error = false;
229 		return -EINVAL;
230 	}
231 	if (vb2_plane_size(vb, 0) < size) {
232 		dprintk(dev, 1, "%s data will not fit into plane (%lu < %u)\n",
233 				__func__, vb2_plane_size(vb, 0), size);
234 		return -EINVAL;
235 	}
236 	vb2_set_plane_payload(vb, 0, size);
237 
238 	return 0;
239 }
240 
sdr_cap_buf_queue(struct vb2_buffer * vb)241 static void sdr_cap_buf_queue(struct vb2_buffer *vb)
242 {
243 	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
244 	struct vivid_dev *dev = vb2_get_drv_priv(vb->vb2_queue);
245 	struct vivid_buffer *buf = container_of(vbuf, struct vivid_buffer, vb);
246 
247 	dprintk(dev, 1, "%s\n", __func__);
248 
249 	spin_lock(&dev->slock);
250 	list_add_tail(&buf->list, &dev->sdr_cap_active);
251 	spin_unlock(&dev->slock);
252 }
253 
sdr_cap_start_streaming(struct vb2_queue * vq,unsigned count)254 static int sdr_cap_start_streaming(struct vb2_queue *vq, unsigned count)
255 {
256 	struct vivid_dev *dev = vb2_get_drv_priv(vq);
257 	int err = 0;
258 
259 	dprintk(dev, 1, "%s\n", __func__);
260 	dev->sdr_cap_seq_count = 0;
261 	if (dev->start_streaming_error) {
262 		dev->start_streaming_error = false;
263 		err = -EINVAL;
264 	} else if (dev->kthread_sdr_cap == NULL) {
265 		dev->kthread_sdr_cap = kthread_run(vivid_thread_sdr_cap, dev,
266 				"%s-sdr-cap", dev->v4l2_dev.name);
267 
268 		if (IS_ERR(dev->kthread_sdr_cap)) {
269 			v4l2_err(&dev->v4l2_dev, "kernel_thread() failed\n");
270 			err = PTR_ERR(dev->kthread_sdr_cap);
271 			dev->kthread_sdr_cap = NULL;
272 		}
273 	}
274 	if (err) {
275 		struct vivid_buffer *buf, *tmp;
276 
277 		list_for_each_entry_safe(buf, tmp, &dev->sdr_cap_active, list) {
278 			list_del(&buf->list);
279 			vb2_buffer_done(&buf->vb.vb2_buf,
280 					VB2_BUF_STATE_QUEUED);
281 		}
282 	}
283 	return err;
284 }
285 
286 /* abort streaming and wait for last buffer */
sdr_cap_stop_streaming(struct vb2_queue * vq)287 static void sdr_cap_stop_streaming(struct vb2_queue *vq)
288 {
289 	struct vivid_dev *dev = vb2_get_drv_priv(vq);
290 
291 	if (dev->kthread_sdr_cap == NULL)
292 		return;
293 
294 	while (!list_empty(&dev->sdr_cap_active)) {
295 		struct vivid_buffer *buf;
296 
297 		buf = list_entry(dev->sdr_cap_active.next,
298 				struct vivid_buffer, list);
299 		list_del(&buf->list);
300 		v4l2_ctrl_request_complete(buf->vb.vb2_buf.req_obj.req,
301 					   &dev->ctrl_hdl_sdr_cap);
302 		vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
303 	}
304 
305 	/* shutdown control thread */
306 	mutex_unlock(&dev->mutex);
307 	kthread_stop(dev->kthread_sdr_cap);
308 	dev->kthread_sdr_cap = NULL;
309 	mutex_lock(&dev->mutex);
310 }
311 
sdr_cap_buf_request_complete(struct vb2_buffer * vb)312 static void sdr_cap_buf_request_complete(struct vb2_buffer *vb)
313 {
314 	struct vivid_dev *dev = vb2_get_drv_priv(vb->vb2_queue);
315 
316 	v4l2_ctrl_request_complete(vb->req_obj.req, &dev->ctrl_hdl_sdr_cap);
317 }
318 
319 const struct vb2_ops vivid_sdr_cap_qops = {
320 	.queue_setup		= sdr_cap_queue_setup,
321 	.buf_prepare		= sdr_cap_buf_prepare,
322 	.buf_queue		= sdr_cap_buf_queue,
323 	.start_streaming	= sdr_cap_start_streaming,
324 	.stop_streaming		= sdr_cap_stop_streaming,
325 	.buf_request_complete	= sdr_cap_buf_request_complete,
326 	.wait_prepare		= vb2_ops_wait_prepare,
327 	.wait_finish		= vb2_ops_wait_finish,
328 };
329 
vivid_sdr_enum_freq_bands(struct file * file,void * fh,struct v4l2_frequency_band * band)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 
vivid_sdr_g_frequency(struct file * file,void * fh,struct v4l2_frequency * vf)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 
vivid_sdr_s_frequency(struct file * file,void * fh,const struct v4l2_frequency * vf)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 
vivid_sdr_g_tuner(struct file * file,void * fh,struct v4l2_tuner * vt)409 int vivid_sdr_g_tuner(struct file *file, void *fh, struct v4l2_tuner *vt)
410 {
411 	switch (vt->index) {
412 	case 0:
413 		strscpy(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 		strscpy(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 
vivid_sdr_s_tuner(struct file * file,void * fh,const struct v4l2_tuner * vt)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 
vidioc_enum_fmt_sdr_cap(struct file * file,void * fh,struct v4l2_fmtdesc * f)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 
vidioc_g_fmt_sdr_cap(struct file * file,void * fh,struct v4l2_format * f)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 
vidioc_s_fmt_sdr_cap(struct file * file,void * fh,struct v4l2_format * f)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 
vidioc_try_fmt_sdr_cap(struct file * file,void * fh,struct v4l2_format * f)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 
vivid_sdr_cap_process(struct vivid_dev * dev,struct vivid_buffer * buf)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 }
569