drivers/rtc/max6900.c

   1 /*
   2  * (C) Copyright 2004
   3  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   4  *
   5  * See file CREDITS for list of people who contributed to this
   6  * project.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation; either version 2 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  21  * MA 02111-1307 USA
  22  */
  23
  24 /*
  25  * Date & Time support for MAXIM MAX6900 RTC
  26  */
  27
  28 /* #define      DEBUG   */
  29
  30 #include <common.h>
  31 #include <command.h>
  32 #include <rtc.h>
  33 #include <i2c.h>
  34
  35 #if defined(CONFIG_RTC_MAX6900) && defined(CONFIG_CMD_DATE)
  36
  37 #ifndef CFG_I2C_RTC_ADDR
  38 #define CFG_I2C_RTC_ADDR        0x50
  39 #endif
  40
  41 /* ------------------------------------------------------------------------- */
  42
  43 static uchar rtc_read (uchar reg)
  44 {
  45         return (i2c_reg_read (CFG_I2C_RTC_ADDR, reg));
  46 }
  47
  48 static void rtc_write (uchar reg, uchar val)
  49 {
  50         i2c_reg_write (CFG_I2C_RTC_ADDR, reg, val);
  51         udelay(2500);
  52 }
  53
  54 static unsigned bcd2bin (uchar n)
  55 {
  56         return ((((n >> 4) & 0x0F) * 10) + (n & 0x0F));
  57 }
  58
  59 static unsigned char bin2bcd (unsigned int n)
  60 {
  61         return (((n / 10) << 4) | (n % 10));
  62 }
  63
  64 /* ------------------------------------------------------------------------- */
  65
  66 void rtc_get (struct rtc_time *tmp)
  67 {
  68         uchar sec, min, hour, mday, wday, mon, cent, year;
  69         int retry = 1;
  70
  71         do {
  72                 sec     = rtc_read (0x80);
  73                 min     = rtc_read (0x82);
  74                 hour    = rtc_read (0x84);
  75                 mday    = rtc_read (0x86);
  76                 mon     = rtc_read (0x88);
  77                 wday    = rtc_read (0x8a);
  78                 year    = rtc_read (0x8c);
  79                 cent    = rtc_read (0x92);
  80                 /*
  81                  * Check for seconds rollover
  82                  */
  83                 if ((sec != 59) || (rtc_read(0x80) == sec)){
  84                         retry = 0;
  85                 }
  86         } while (retry);
  87
  88         debug ( "Get RTC year: %02x mon: %02x cent: %02x mday: %02x wday: %02x "
  89                 "hr: %02x min: %02x sec: %02x\n",
  90                 year, mon, cent, mday, wday,
  91                 hour, min, sec );
  92
  93         tmp->tm_sec  = bcd2bin (sec  & 0x7F);
  94         tmp->tm_min  = bcd2bin (min  & 0x7F);
  95         tmp->tm_hour = bcd2bin (hour & 0x3F);
  96         tmp->tm_mday = bcd2bin (mday & 0x3F);
  97         tmp->tm_mon  = bcd2bin (mon & 0x1F);
  98         tmp->tm_year = bcd2bin (year) + bcd2bin(cent) * 100;
  99         tmp->tm_wday = bcd2bin (wday & 0x07);
 100         tmp->tm_yday = 0;
 101         tmp->tm_isdst= 0;
 102
 103         debug ( "Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 104                 tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
 105                 tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
 106 }
 107
 108 void rtc_set (struct rtc_time *tmp)
 109 {
 110
 111         debug ( "Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 112                 tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
 113                 tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
 114
 115         rtc_write (0x9E, 0x00);
 116         rtc_write (0x80, 0);    /* Clear seconds to ensure no rollover */
 117         rtc_write (0x92, bin2bcd(tmp->tm_year / 100));
 118         rtc_write (0x8c, bin2bcd(tmp->tm_year % 100));
 119         rtc_write (0x8a, bin2bcd(tmp->tm_wday));
 120         rtc_write (0x88, bin2bcd(tmp->tm_mon));
 121         rtc_write (0x86, bin2bcd(tmp->tm_mday));
 122         rtc_write (0x84, bin2bcd(tmp->tm_hour));
 123         rtc_write (0x82, bin2bcd(tmp->tm_min ));
 124         rtc_write (0x80, bin2bcd(tmp->tm_sec ));
 125 }
 126
 127 void rtc_reset (void)
 128 {
 129 }
 130
 131 #endif