1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * vivid-vbi-gen.c - vbi generator 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/ktime.h>
11#include <linux/string.h>
12#include <linux/videodev2.h>
13
14#include "vivid-vbi-gen.h"
15
16static void wss_insert(u8 *wss, u32 val, unsigned size)
17{
18	while (size--)
19		*wss++ = (val & (1 << size)) ? 0xc0 : 0x10;
20}
21
22static void vivid_vbi_gen_wss_raw(const struct v4l2_sliced_vbi_data *data,
23		u8 *buf, unsigned sampling_rate)
24{
25	const unsigned rate = 5000000;	/* WSS has a 5 MHz transmission rate */
26	u8 wss[29 + 24 + 24 + 24 + 18 + 18] = { 0 };
27	const unsigned zero = 0x07;
28	const unsigned one = 0x38;
29	unsigned bit = 0;
30	u16 wss_data;
31	int i;
32
33	wss_insert(wss + bit, 0x1f1c71c7, 29); bit += 29;
34	wss_insert(wss + bit, 0x1e3c1f, 24); bit += 24;
35
36	wss_data = (data->data[1] << 8) | data->data[0];
37	for (i = 0; i <= 13; i++, bit += 6)
38		wss_insert(wss + bit, (wss_data & (1 << i)) ? one : zero, 6);
39
40	for (i = 0, bit = 0; bit < sizeof(wss); bit++) {
41		unsigned n = ((bit + 1) * sampling_rate) / rate;
42
43		while (i < n)
44			buf[i++] = wss[bit];
45	}
46}
47
48static void vivid_vbi_gen_teletext_raw(const struct v4l2_sliced_vbi_data *data,
49		u8 *buf, unsigned sampling_rate)
50{
51	const unsigned rate = 6937500 / 10;	/* Teletext has a 6.9375 MHz transmission rate */
52	u8 teletext[45] = { 0x55, 0x55, 0x27 };
53	unsigned bit = 0;
54	int i;
55
56	memcpy(teletext + 3, data->data, sizeof(teletext) - 3);
57	/* prevents 32 bit overflow */
58	sampling_rate /= 10;
59
60	for (i = 0, bit = 0; bit < sizeof(teletext) * 8; bit++) {
61		unsigned n = ((bit + 1) * sampling_rate) / rate;
62		u8 val = (teletext[bit / 8] & (1 << (bit & 7))) ? 0xc0 : 0x10;
63
64		while (i < n)
65			buf[i++] = val;
66	}
67}
68
69static void cc_insert(u8 *cc, u8 ch)
70{
71	unsigned tot = 0;
72	unsigned i;
73
74	for (i = 0; i < 7; i++) {
75		cc[2 * i] = cc[2 * i + 1] = (ch & (1 << i)) ? 1 : 0;
76		tot += cc[2 * i];
77	}
78	cc[14] = cc[15] = !(tot & 1);
79}
80
81#define CC_PREAMBLE_BITS (14 + 4 + 2)
82
83static void vivid_vbi_gen_cc_raw(const struct v4l2_sliced_vbi_data *data,
84		u8 *buf, unsigned sampling_rate)
85{
86	const unsigned rate = 1000000;	/* CC has a 1 MHz transmission rate */
87
88	u8 cc[CC_PREAMBLE_BITS + 2 * 16] = {
89		/* Clock run-in: 7 cycles */
90		0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1,
91		/* 2 cycles of 0 */
92		0, 0, 0, 0,
93		/* Start bit of 1 (each bit is two cycles) */
94		1, 1
95	};
96	unsigned bit, i;
97
98	cc_insert(cc + CC_PREAMBLE_BITS, data->data[0]);
99	cc_insert(cc + CC_PREAMBLE_BITS + 16, data->data[1]);
100
101	for (i = 0, bit = 0; bit < sizeof(cc); bit++) {
102		unsigned n = ((bit + 1) * sampling_rate) / rate;
103
104		while (i < n)
105			buf[i++] = cc[bit] ? 0xc0 : 0x10;
106	}
107}
108
109void vivid_vbi_gen_raw(const struct vivid_vbi_gen_data *vbi,
110		const struct v4l2_vbi_format *vbi_fmt, u8 *buf)
111{
112	unsigned idx;
113
114	for (idx = 0; idx < 25; idx++) {
115		const struct v4l2_sliced_vbi_data *data = vbi->data + idx;
116		unsigned start_2nd_field;
117		unsigned line = data->line;
118		u8 *linebuf = buf;
119
120		start_2nd_field = (data->id & V4L2_SLICED_VBI_525) ? 263 : 313;
121		if (data->field)
122			line += start_2nd_field;
123		line -= vbi_fmt->start[data->field];
124
125		if (vbi_fmt->flags & V4L2_VBI_INTERLACED)
126			linebuf += (line * 2 + data->field) *
127				vbi_fmt->samples_per_line;
128		else
129			linebuf += (line + data->field * vbi_fmt->count[0]) *
130				vbi_fmt->samples_per_line;
131		if (data->id == V4L2_SLICED_CAPTION_525)
132			vivid_vbi_gen_cc_raw(data, linebuf, vbi_fmt->sampling_rate);
133		else if (data->id == V4L2_SLICED_WSS_625)
134			vivid_vbi_gen_wss_raw(data, linebuf, vbi_fmt->sampling_rate);
135		else if (data->id == V4L2_SLICED_TELETEXT_B)
136			vivid_vbi_gen_teletext_raw(data, linebuf, vbi_fmt->sampling_rate);
137	}
138}
139
140static const u8 vivid_cc_sequence1[30] = {
141	0x14, 0x20,	/* Resume Caption Loading */
142	'H',  'e',
143	'l',  'l',
144	'o',  ' ',
145	'w',  'o',
146	'r',  'l',
147	'd',  '!',
148	0x14, 0x2f,	/* End of Caption */
149};
150
151static const u8 vivid_cc_sequence2[30] = {
152	0x14, 0x20,	/* Resume Caption Loading */
153	'C',  'l',
154	'o',  's',
155	'e',  'd',
156	' ',  'c',
157	'a',  'p',
158	't',  'i',
159	'o',  'n',
160	's',  ' ',
161	't',  'e',
162	's',  't',
163	0x14, 0x2f,	/* End of Caption */
164};
165
166static u8 calc_parity(u8 val)
167{
168	unsigned i;
169	unsigned tot = 0;
170
171	for (i = 0; i < 7; i++)
172		tot += (val & (1 << i)) ? 1 : 0;
173	return val | ((tot & 1) ? 0 : 0x80);
174}
175
176static void vivid_vbi_gen_set_time_of_day(u8 *packet)
177{
178	struct tm tm;
179	u8 checksum, i;
180
181	time64_to_tm(ktime_get_real_seconds(), 0, &tm);
182	packet[0] = calc_parity(0x07);
183	packet[1] = calc_parity(0x01);
184	packet[2] = calc_parity(0x40 | tm.tm_min);
185	packet[3] = calc_parity(0x40 | tm.tm_hour);
186	packet[4] = calc_parity(0x40 | tm.tm_mday);
187	if (tm.tm_mday == 1 && tm.tm_mon == 2 &&
188	    sys_tz.tz_minuteswest > tm.tm_min + tm.tm_hour * 60)
189		packet[4] = calc_parity(0x60 | tm.tm_mday);
190	packet[5] = calc_parity(0x40 | (1 + tm.tm_mon));
191	packet[6] = calc_parity(0x40 | (1 + tm.tm_wday));
192	packet[7] = calc_parity(0x40 | ((tm.tm_year - 90) & 0x3f));
193	packet[8] = calc_parity(0x0f);
194	for (checksum = i = 0; i <= 8; i++)
195		checksum += packet[i] & 0x7f;
196	packet[9] = calc_parity(0x100 - checksum);
197	checksum = 0;
198	packet[10] = calc_parity(0x07);
199	packet[11] = calc_parity(0x04);
200	if (sys_tz.tz_minuteswest >= 0)
201		packet[12] = calc_parity(0x40 | ((sys_tz.tz_minuteswest / 60) & 0x1f));
202	else
203		packet[12] = calc_parity(0x40 | ((24 + sys_tz.tz_minuteswest / 60) & 0x1f));
204	packet[13] = calc_parity(0);
205	packet[14] = calc_parity(0x0f);
206	for (checksum = 0, i = 10; i <= 14; i++)
207		checksum += packet[i] & 0x7f;
208	packet[15] = calc_parity(0x100 - checksum);
209}
210
211static const u8 hamming[16] = {
212	0x15, 0x02, 0x49, 0x5e, 0x64, 0x73, 0x38, 0x2f,
213	0xd0, 0xc7, 0x8c, 0x9b, 0xa1, 0xb6, 0xfd, 0xea
214};
215
216static void vivid_vbi_gen_teletext(u8 *packet, unsigned line, unsigned frame)
217{
218	unsigned offset = 2;
219	unsigned i;
220
221	packet[0] = hamming[1 + ((line & 1) << 3)];
222	packet[1] = hamming[line >> 1];
223	memset(packet + 2, 0x20, 40);
224	if (line == 0) {
225		/* subcode */
226		packet[2] = hamming[frame % 10];
227		packet[3] = hamming[frame / 10];
228		packet[4] = hamming[0];
229		packet[5] = hamming[0];
230		packet[6] = hamming[0];
231		packet[7] = hamming[0];
232		packet[8] = hamming[0];
233		packet[9] = hamming[1];
234		offset = 10;
235	}
236	packet += offset;
237	memcpy(packet, "Page: 100 Row: 10", 17);
238	packet[7] = '0' + frame / 10;
239	packet[8] = '0' + frame % 10;
240	packet[15] = '0' + line / 10;
241	packet[16] = '0' + line % 10;
242	for (i = 0; i < 42 - offset; i++)
243		packet[i] = calc_parity(packet[i]);
244}
245
246void vivid_vbi_gen_sliced(struct vivid_vbi_gen_data *vbi,
247		bool is_60hz, unsigned seqnr)
248{
249	struct v4l2_sliced_vbi_data *data0 = vbi->data;
250	struct v4l2_sliced_vbi_data *data1 = vbi->data + 1;
251	unsigned frame = seqnr % 60;
252
253	memset(vbi->data, 0, sizeof(vbi->data));
254
255	if (!is_60hz) {
256		unsigned i;
257
258		for (i = 0; i <= 11; i++) {
259			data0->id = V4L2_SLICED_TELETEXT_B;
260			data0->line = 7 + i;
261			vivid_vbi_gen_teletext(data0->data, i, frame);
262			data0++;
263		}
264		data0->id = V4L2_SLICED_WSS_625;
265		data0->line = 23;
266		/* 4x3 video aspect ratio */
267		data0->data[0] = 0x08;
268		data0++;
269		for (i = 0; i <= 11; i++) {
270			data0->id = V4L2_SLICED_TELETEXT_B;
271			data0->field = 1;
272			data0->line = 7 + i;
273			vivid_vbi_gen_teletext(data0->data, 12 + i, frame);
274			data0++;
275		}
276		return;
277	}
278
279	data0->id = V4L2_SLICED_CAPTION_525;
280	data0->line = 21;
281	data1->id = V4L2_SLICED_CAPTION_525;
282	data1->field = 1;
283	data1->line = 21;
284
285	if (frame < 15) {
286		data0->data[0] = calc_parity(vivid_cc_sequence1[2 * frame]);
287		data0->data[1] = calc_parity(vivid_cc_sequence1[2 * frame + 1]);
288	} else if (frame >= 30 && frame < 45) {
289		frame -= 30;
290		data0->data[0] = calc_parity(vivid_cc_sequence2[2 * frame]);
291		data0->data[1] = calc_parity(vivid_cc_sequence2[2 * frame + 1]);
292	} else {
293		data0->data[0] = calc_parity(0);
294		data0->data[1] = calc_parity(0);
295	}
296
297	frame = seqnr % (30 * 60);
298	switch (frame) {
299	case 0:
300		vivid_vbi_gen_set_time_of_day(vbi->time_of_day_packet);
301		fallthrough;
302	case 1 ... 7:
303		data1->data[0] = vbi->time_of_day_packet[frame * 2];
304		data1->data[1] = vbi->time_of_day_packet[frame * 2 + 1];
305		break;
306	default:
307		data1->data[0] = calc_parity(0);
308		data1->data[1] = calc_parity(0);
309		break;
310	}
311}
312