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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * vivid-rds-gen.c - rds (radio data system) generator support functions.4 *5 * Copyright 2014 Cisco Systems, Inc. and/or its affiliates. All rights reserved.6 */7 8#include <linux/kernel.h>9#include <linux/ktime.h>10#include <linux/string.h>11#include <linux/videodev2.h>12 13#include "vivid-rds-gen.h"14 15static u8 vivid_get_di(const struct vivid_rds_gen *rds, unsigned grp)16{17 switch (grp) {18 case 0:19 return (rds->dyn_pty << 2) | (grp & 3);20 case 1:21 return (rds->compressed << 2) | (grp & 3);22 case 2:23 return (rds->art_head << 2) | (grp & 3);24 case 3:25 return (rds->mono_stereo << 2) | (grp & 3);26 }27 return 0;28}29 30/*31 * This RDS generator creates 57 RDS groups (one group == four RDS blocks).32 * Groups 0-3, 22-25 and 44-47 (spaced 22 groups apart) are filled with a33 * standard 0B group containing the PI code and PS name.34 *35 * Groups 4-19 and 26-41 use group 2A for the radio text.36 *37 * Group 56 contains the time (group 4A).38 *39 * All remaining groups use a filler group 15B block that just repeats40 * the PI and PTY codes.41 */42void vivid_rds_generate(struct vivid_rds_gen *rds)43{44 struct v4l2_rds_data *data = rds->data;45 unsigned grp;46 unsigned idx;47 struct tm tm;48 unsigned date;49 unsigned time;50 int l;51 52 for (grp = 0; grp < VIVID_RDS_GEN_GROUPS; grp++, data += VIVID_RDS_GEN_BLKS_PER_GRP) {53 data[0].lsb = rds->picode & 0xff;54 data[0].msb = rds->picode >> 8;55 data[0].block = V4L2_RDS_BLOCK_A | (V4L2_RDS_BLOCK_A << 3);56 data[1].lsb = rds->pty << 5;57 data[1].msb = (rds->pty >> 3) | (rds->tp << 2);58 data[1].block = V4L2_RDS_BLOCK_B | (V4L2_RDS_BLOCK_B << 3);59 data[3].block = V4L2_RDS_BLOCK_D | (V4L2_RDS_BLOCK_D << 3);60 61 switch (grp) {62 case 0 ... 3:63 case 22 ... 25:64 case 44 ... 47: /* Group 0B */65 idx = (grp % 22) % 4;66 data[1].lsb |= (rds->ta << 4) | (rds->ms << 3);67 data[1].lsb |= vivid_get_di(rds, idx);68 data[1].msb |= 1 << 3;69 data[2].lsb = rds->picode & 0xff;70 data[2].msb = rds->picode >> 8;71 data[2].block = V4L2_RDS_BLOCK_C_ALT | (V4L2_RDS_BLOCK_C_ALT << 3);72 data[3].lsb = rds->psname[2 * idx + 1];73 data[3].msb = rds->psname[2 * idx];74 break;75 case 4 ... 19:76 case 26 ... 41: /* Group 2A */77 idx = ((grp - 4) % 22) % 16;78 data[1].lsb |= idx;79 data[1].msb |= 4 << 3;80 data[2].msb = rds->radiotext[4 * idx];81 data[2].lsb = rds->radiotext[4 * idx + 1];82 data[2].block = V4L2_RDS_BLOCK_C | (V4L2_RDS_BLOCK_C << 3);83 data[3].msb = rds->radiotext[4 * idx + 2];84 data[3].lsb = rds->radiotext[4 * idx + 3];85 break;86 case 56:87 /*88 * Group 4A89 *90 * Uses the algorithm from Annex G of the RDS standard91 * EN 50067:1998 to convert a UTC date to an RDS Modified92 * Julian Day.93 */94 time64_to_tm(ktime_get_real_seconds(), 0, &tm);95 l = tm.tm_mon <= 1;96 date = 14956 + tm.tm_mday + ((tm.tm_year - l) * 1461) / 4 +97 ((tm.tm_mon + 2 + l * 12) * 306001) / 10000;98 time = (tm.tm_hour << 12) |99 (tm.tm_min << 6) |100 (sys_tz.tz_minuteswest >= 0 ? 0x20 : 0) |101 (abs(sys_tz.tz_minuteswest) / 30);102 data[1].lsb &= ~3;103 data[1].lsb |= date >> 15;104 data[1].msb |= 8 << 3;105 data[2].lsb = (date << 1) & 0xfe;106 data[2].lsb |= (time >> 16) & 1;107 data[2].msb = (date >> 7) & 0xff;108 data[2].block = V4L2_RDS_BLOCK_C | (V4L2_RDS_BLOCK_C << 3);109 data[3].lsb = time & 0xff;110 data[3].msb = (time >> 8) & 0xff;111 break;112 default: /* Group 15B */113 data[1].lsb |= (rds->ta << 4) | (rds->ms << 3);114 data[1].lsb |= vivid_get_di(rds, grp % 22);115 data[1].msb |= 0x1f << 3;116 data[2].lsb = rds->picode & 0xff;117 data[2].msb = rds->picode >> 8;118 data[2].block = V4L2_RDS_BLOCK_C_ALT | (V4L2_RDS_BLOCK_C_ALT << 3);119 data[3].lsb = rds->pty << 5;120 data[3].lsb |= (rds->ta << 4) | (rds->ms << 3);121 data[3].lsb |= vivid_get_di(rds, grp % 22);122 data[3].msb |= rds->pty >> 3;123 data[3].msb |= 0x1f << 3;124 break;125 }126 }127}128 129void vivid_rds_gen_fill(struct vivid_rds_gen *rds, unsigned freq,130 bool alt)131{132 /* Alternate PTY between Info and Weather */133 if (rds->use_rbds) {134 rds->picode = 0x2e75; /* 'KLNX' call sign */135 rds->pty = alt ? 29 : 2;136 } else {137 rds->picode = 0x8088;138 rds->pty = alt ? 16 : 3;139 }140 rds->mono_stereo = true;141 rds->art_head = false;142 rds->compressed = false;143 rds->dyn_pty = false;144 rds->tp = true;145 rds->ta = alt;146 rds->ms = true;147 snprintf(rds->psname, sizeof(rds->psname), "%6d.%1d",148 (freq / 16) % 1000000, (((freq & 0xf) * 10) / 16) % 10);149 if (alt)150 strscpy(rds->radiotext,151 " The Radio Data System can switch between different Radio Texts ",152 sizeof(rds->radiotext));153 else154 strscpy(rds->radiotext,155 "An example of Radio Text as transmitted by the Radio Data System",156 sizeof(rds->radiotext));157}158