// SPDX-License-Identifier: GPL-2.0-only
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/*
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* vivid-rds-gen.c - rds (radio data system) generator support functions.
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*
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* Copyright 2014 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
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*/
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#include <linux/kernel.h>
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#include <linux/ktime.h>
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#include <linux/string.h>
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#include <linux/videodev2.h>
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#include "vivid-rds-gen.h"
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static u8 vivid_get_di(const struct vivid_rds_gen *rds, unsigned grp)
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{
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switch (grp) {
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case 0:
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return (rds->dyn_pty << 2) | (grp & 3);
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case 1:
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return (rds->compressed << 2) | (grp & 3);
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case 2:
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return (rds->art_head << 2) | (grp & 3);
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case 3:
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return (rds->mono_stereo << 2) | (grp & 3);
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}
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return 0;
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}
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/*
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* This RDS generator creates 57 RDS groups (one group == four RDS blocks).
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* Groups 0-3, 22-25 and 44-47 (spaced 22 groups apart) are filled with a
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* standard 0B group containing the PI code and PS name.
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*
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* Groups 4-19 and 26-41 use group 2A for the radio text.
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*
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* Group 56 contains the time (group 4A).
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*
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* All remaining groups use a filler group 15B block that just repeats
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* the PI and PTY codes.
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*/
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void vivid_rds_generate(struct vivid_rds_gen *rds)
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{
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struct v4l2_rds_data *data = rds->data;
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unsigned grp;
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unsigned idx;
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struct tm tm;
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unsigned date;
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unsigned time;
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int l;
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for (grp = 0; grp < VIVID_RDS_GEN_GROUPS; grp++, data += VIVID_RDS_GEN_BLKS_PER_GRP) {
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data[0].lsb = rds->picode & 0xff;
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data[0].msb = rds->picode >> 8;
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data[0].block = V4L2_RDS_BLOCK_A | (V4L2_RDS_BLOCK_A << 3);
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data[1].lsb = rds->pty << 5;
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data[1].msb = (rds->pty >> 3) | (rds->tp << 2);
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data[1].block = V4L2_RDS_BLOCK_B | (V4L2_RDS_BLOCK_B << 3);
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data[3].block = V4L2_RDS_BLOCK_D | (V4L2_RDS_BLOCK_D << 3);
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switch (grp) {
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case 0 ... 3:
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case 22 ... 25:
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case 44 ... 47: /* Group 0B */
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idx = (grp % 22) % 4;
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data[1].lsb |= (rds->ta << 4) | (rds->ms << 3);
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data[1].lsb |= vivid_get_di(rds, idx);
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data[1].msb |= 1 << 3;
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data[2].lsb = rds->picode & 0xff;
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data[2].msb = rds->picode >> 8;
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data[2].block = V4L2_RDS_BLOCK_C_ALT | (V4L2_RDS_BLOCK_C_ALT << 3);
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data[3].lsb = rds->psname[2 * idx + 1];
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data[3].msb = rds->psname[2 * idx];
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break;
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case 4 ... 19:
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case 26 ... 41: /* Group 2A */
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idx = ((grp - 4) % 22) % 16;
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data[1].lsb |= idx;
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data[1].msb |= 4 << 3;
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data[2].msb = rds->radiotext[4 * idx];
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data[2].lsb = rds->radiotext[4 * idx + 1];
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data[2].block = V4L2_RDS_BLOCK_C | (V4L2_RDS_BLOCK_C << 3);
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data[3].msb = rds->radiotext[4 * idx + 2];
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data[3].lsb = rds->radiotext[4 * idx + 3];
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break;
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case 56:
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/*
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* Group 4A
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*
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* Uses the algorithm from Annex G of the RDS standard
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* EN 50067:1998 to convert a UTC date to an RDS Modified
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* Julian Day.
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*/
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time64_to_tm(ktime_get_real_seconds(), 0, &tm);
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l = tm.tm_mon <= 1;
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date = 14956 + tm.tm_mday + ((tm.tm_year - l) * 1461) / 4 +
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((tm.tm_mon + 2 + l * 12) * 306001) / 10000;
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time = (tm.tm_hour << 12) |
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(tm.tm_min << 6) |
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(sys_tz.tz_minuteswest >= 0 ? 0x20 : 0) |
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(abs(sys_tz.tz_minuteswest) / 30);
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data[1].lsb &= ~3;
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data[1].lsb |= date >> 15;
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data[1].msb |= 8 << 3;
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data[2].lsb = (date << 1) & 0xfe;
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data[2].lsb |= (time >> 16) & 1;
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data[2].msb = (date >> 7) & 0xff;
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data[2].block = V4L2_RDS_BLOCK_C | (V4L2_RDS_BLOCK_C << 3);
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data[3].lsb = time & 0xff;
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data[3].msb = (time >> 8) & 0xff;
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break;
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default: /* Group 15B */
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data[1].lsb |= (rds->ta << 4) | (rds->ms << 3);
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data[1].lsb |= vivid_get_di(rds, grp % 22);
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data[1].msb |= 0x1f << 3;
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data[2].lsb = rds->picode & 0xff;
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data[2].msb = rds->picode >> 8;
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data[2].block = V4L2_RDS_BLOCK_C_ALT | (V4L2_RDS_BLOCK_C_ALT << 3);
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data[3].lsb = rds->pty << 5;
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data[3].lsb |= (rds->ta << 4) | (rds->ms << 3);
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data[3].lsb |= vivid_get_di(rds, grp % 22);
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data[3].msb |= rds->pty >> 3;
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data[3].msb |= 0x1f << 3;
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break;
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}
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}
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}
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void vivid_rds_gen_fill(struct vivid_rds_gen *rds, unsigned freq,
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bool alt)
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{
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/* Alternate PTY between Info and Weather */
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if (rds->use_rbds) {
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rds->picode = 0x2e75; /* 'KLNX' call sign */
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rds->pty = alt ? 29 : 2;
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} else {
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rds->picode = 0x8088;
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rds->pty = alt ? 16 : 3;
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}
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rds->mono_stereo = true;
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rds->art_head = false;
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rds->compressed = false;
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rds->dyn_pty = false;
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rds->tp = true;
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rds->ta = alt;
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rds->ms = true;
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snprintf(rds->psname, sizeof(rds->psname), "%6d.%1d",
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freq / 16, ((freq & 0xf) * 10) / 16);
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if (alt)
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strscpy(rds->radiotext,
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" The Radio Data System can switch between different Radio Texts ",
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sizeof(rds->radiotext));
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else
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strscpy(rds->radiotext,
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"An example of Radio Text as transmitted by the Radio Data System",
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sizeof(rds->radiotext));
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}
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