drivers/media/platform/vivid/vivid-rds-gen.c

   1 /*
   2  * vivid-rds-gen.c - rds (radio data system) generator support functions.
   3  *
   4  * Copyright 2014 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
   5  *
   6  * This program is free software; you may redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; version 2 of the License.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  11  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  12  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  13  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  14  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  15  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  16  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  17  * SOFTWARE.
  18  */
  19
  20 #include <linux/kernel.h>
  21 #include <linux/ktime.h>
  22 #include <linux/string.h>
  23 #include <linux/videodev2.h>
  24
  25 #include "vivid-rds-gen.h"
  26
  27 static u8 vivid_get_di(const struct vivid_rds_gen *rds, unsigned grp)
  28 {
  29         switch (grp) {
  30         case 0:
  31                 return (rds->dyn_pty << 2) | (grp & 3);
  32         case 1:
  33                 return (rds->compressed << 2) | (grp & 3);
  34         case 2:
  35                 return (rds->art_head << 2) | (grp & 3);
  36         case 3:
  37                 return (rds->mono_stereo << 2) | (grp & 3);
  38         }
  39         return 0;
  40 }
  41
  42 /*
  43  * This RDS generator creates 57 RDS groups (one group == four RDS blocks).
  44  * Groups 0-3, 22-25 and 44-47 (spaced 22 groups apart) are filled with a
  45  * standard 0B group containing the PI code and PS name.
  46  *
  47  * Groups 4-19 and 26-41 use group 2A for the radio text.
  48  *
  49  * Group 56 contains the time (group 4A).
  50  *
  51  * All remaining groups use a filler group 15B block that just repeats
  52  * the PI and PTY codes.
  53  */
  54 void vivid_rds_generate(struct vivid_rds_gen *rds)
  55 {
  56         struct v4l2_rds_data *data = rds->data;
  57         unsigned grp;
  58         unsigned idx;
  59         struct tm tm;
  60         unsigned date;
  61         unsigned time;
  62         int l;
  63
  64         for (grp = 0; grp < VIVID_RDS_GEN_GROUPS; grp++, data += VIVID_RDS_GEN_BLKS_PER_GRP) {
  65                 data[0].lsb = rds->picode & 0xff;
  66                 data[0].msb = rds->picode >> 8;
  67                 data[0].block = V4L2_RDS_BLOCK_A | (V4L2_RDS_BLOCK_A << 3);
  68                 data[1].lsb = rds->pty << 5;
  69                 data[1].msb = (rds->pty >> 3) | (rds->tp << 2);
  70                 data[1].block = V4L2_RDS_BLOCK_B | (V4L2_RDS_BLOCK_B << 3);
  71                 data[3].block = V4L2_RDS_BLOCK_D | (V4L2_RDS_BLOCK_D << 3);
  72
  73                 switch (grp) {
  74                 case 0 ... 3:
  75                 case 22 ... 25:
  76                 case 44 ... 47: /* Group 0B */
  77                         idx = (grp % 22) % 4;
  78                         data[1].lsb |= (rds->ta << 4) | (rds->ms << 3);
  79                         data[1].lsb |= vivid_get_di(rds, idx);
  80                         data[1].msb |= 1 << 3;
  81                         data[2].lsb = rds->picode & 0xff;
  82                         data[2].msb = rds->picode >> 8;
  83                         data[2].block = V4L2_RDS_BLOCK_C_ALT | (V4L2_RDS_BLOCK_C_ALT << 3);
  84                         data[3].lsb = rds->psname[2 * idx + 1];
  85                         data[3].msb = rds->psname[2 * idx];
  86                         break;
  87                 case 4 ... 19:
  88                 case 26 ... 41: /* Group 2A */
  89                         idx = ((grp - 4) % 22) % 16;
  90                         data[1].lsb |= idx;
  91                         data[1].msb |= 4 << 3;
  92                         data[2].msb = rds->radiotext[4 * idx];
  93                         data[2].lsb = rds->radiotext[4 * idx + 1];
  94                         data[2].block = V4L2_RDS_BLOCK_C | (V4L2_RDS_BLOCK_C << 3);
  95                         data[3].msb = rds->radiotext[4 * idx + 2];
  96                         data[3].lsb = rds->radiotext[4 * idx + 3];
  97                         break;
  98                 case 56:
  99                         /*
 100                          * Group 4A
 101                          *
 102                          * Uses the algorithm from Annex G of the RDS standard
 103                          * EN 50067:1998 to convert a UTC date to an RDS Modified
 104                          * Julian Day.
 105                          */
 106                         time64_to_tm(ktime_get_real_seconds(), 0, &tm);
 107                         l = tm.tm_mon <= 1;
 108                         date = 14956 + tm.tm_mday + ((tm.tm_year - l) * 1461) / 4 +
 109                                 ((tm.tm_mon + 2 + l * 12) * 306001) / 10000;
 110                         time = (tm.tm_hour << 12) |
 111                                (tm.tm_min << 6) |
 112                                (sys_tz.tz_minuteswest >= 0 ? 0x20 : 0) |
 113                                (abs(sys_tz.tz_minuteswest) / 30);
 114                         data[1].lsb &= ~3;
 115                         data[1].lsb |= date >> 15;
 116                         data[1].msb |= 8 << 3;
 117                         data[2].lsb = (date << 1) & 0xfe;
 118                         data[2].lsb |= (time >> 16) & 1;
 119                         data[2].msb = (date >> 7) & 0xff;
 120                         data[2].block = V4L2_RDS_BLOCK_C | (V4L2_RDS_BLOCK_C << 3);
 121                         data[3].lsb = time & 0xff;
 122                         data[3].msb = (time >> 8) & 0xff;
 123                         break;
 124                 default: /* Group 15B */
 125                         data[1].lsb |= (rds->ta << 4) | (rds->ms << 3);
 126                         data[1].lsb |= vivid_get_di(rds, grp % 22);
 127                         data[1].msb |= 0x1f << 3;
 128                         data[2].lsb = rds->picode & 0xff;
 129                         data[2].msb = rds->picode >> 8;
 130                         data[2].block = V4L2_RDS_BLOCK_C_ALT | (V4L2_RDS_BLOCK_C_ALT << 3);
 131                         data[3].lsb = rds->pty << 5;
 132                         data[3].lsb |= (rds->ta << 4) | (rds->ms << 3);
 133                         data[3].lsb |= vivid_get_di(rds, grp % 22);
 134                         data[3].msb |= rds->pty >> 3;
 135                         data[3].msb |= 0x1f << 3;
 136                         break;
 137                 }
 138         }
 139 }
 140
 141 void vivid_rds_gen_fill(struct vivid_rds_gen *rds, unsigned freq,
 142                           bool alt)
 143 {
 144         /* Alternate PTY between Info and Weather */
 145         if (rds->use_rbds) {
 146                 rds->picode = 0x2e75; /* 'KLNX' call sign */
 147                 rds->pty = alt ? 29 : 2;
 148         } else {
 149                 rds->picode = 0x8088;
 150                 rds->pty = alt ? 16 : 3;
 151         }
 152         rds->mono_stereo = true;
 153         rds->art_head = false;
 154         rds->compressed = false;
 155         rds->dyn_pty = false;
 156         rds->tp = true;
 157         rds->ta = alt;
 158         rds->ms = true;
 159         snprintf(rds->psname, sizeof(rds->psname), "%6d.%1d",
 160                  freq / 16, ((freq & 0xf) * 10) / 16);
 161         if (alt)
 162                 strlcpy(rds->radiotext,
 163                         " The Radio Data System can switch between different Radio Texts ",
 164                         sizeof(rds->radiotext));
 165         else
 166                 strlcpy(rds->radiotext,
 167                         "An example of Radio Text as transmitted by the Radio Data System",
 168                         sizeof(rds->radiotext));
 169 }