drivers/rtc/m41t60.c

   1 /*
   2  * (C) Copyright 2007
   3  * Larry Johnson, lrj@acm.org
   4  *
   5  * based on rtc/m41t11.c which is ...
   6  *
   7  * (C) Copyright 2002
   8  * Andrew May, Viasat Inc, amay@viasat.com
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License as
  12  * published by the Free Software Foundation; either version 2 of
  13  * the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  23  * MA 02111-1307 USA
  24  */
  25
  26 /*
  27  * STMicroelectronics M41T60 serial access real-time clock
  28  */
  29
  30 /* #define DEBUG 1 */
  31
  32 #include <common.h>
  33 #include <command.h>
  34 #include <rtc.h>
  35 #include <i2c.h>
  36
  37 #if defined(CONFIG_RTC_M41T60) && defined(CFG_I2C_RTC_ADDR) && \
  38         defined(CONFIG_CMD_DATE)
  39
  40 static unsigned bcd2bin(uchar n)
  41 {
  42         return ((((n >> 4) & 0x0F) * 10) + (n & 0x0F));
  43 }
  44
  45 static unsigned char bin2bcd(unsigned int n)
  46 {
  47         return (((n / 10) << 4) | (n % 10));
  48 }
  49
  50 /*
  51  * Convert between century and "century bits" (CB1 and CB0).  These routines
  52  * assume years are in the range 1900 - 2299.
  53  */
  54
  55 static unsigned char year2cb(unsigned const year)
  56 {
  57         if (year < 1900 || year >= 2300)
  58                 printf("M41T60 RTC: year %d out of range\n", year);
  59
  60         return (year / 100) & 0x3;
  61 }
  62
  63 static unsigned cb2year(unsigned const cb)
  64 {
  65         return 1900 + 100 * ((cb + 1) & 0x3);
  66 }
  67
  68 /*
  69  * These are simple defines for the chip local to here so they aren't too
  70  * verbose.  DAY/DATE aren't nice but that is how they are on the data sheet.
  71  */
  72 #define RTC_SEC         0x0
  73 #define RTC_MIN         0x1
  74 #define RTC_HOUR        0x2
  75 #define RTC_DAY         0x3
  76 #define RTC_DATE        0x4
  77 #define RTC_MONTH       0x5
  78 #define RTC_YEAR        0x6
  79
  80 #define RTC_REG_CNT     7
  81
  82 #define RTC_CTRL        0x7
  83
  84 #if defined(DEBUG)
  85 static void rtc_dump(char const *const label)
  86 {
  87         uchar data[8];
  88
  89         if (i2c_read(CFG_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
  90                 printf("I2C read failed in rtc_dump()\n");
  91                 return;
  92         }
  93         printf("RTC dump %s: %02X-%02X-%02X-%02X-%02X-%02X-%02X-%02X\n",
  94                label, data[0], data[1], data[2], data[3],
  95                data[4], data[5], data[6], data[7]);
  96 }
  97 #else
  98 #define rtc_dump(label)
  99 #endif
 100
 101 static uchar *rtc_validate(void)
 102 {
 103         /*
 104          * This routine uses the OUT bit and the validity of the time values to
 105          * determine whether there has been an initial power-up since the last
 106          * time the routine was run.  It assumes that the OUT bit is not being
 107          * used for any other purpose.
 108          */
 109         static const uchar daysInMonth[0x13] = {
 110                 0x00, 0x31, 0x29, 0x31, 0x30, 0x31, 0x30, 0x31,
 111                 0x31, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 112                 0x31, 0x30, 0x31
 113         };
 114         static uchar data[8];
 115         uchar min, date, month, years;
 116
 117         rtc_dump("begin validate");
 118         if (i2c_read(CFG_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
 119                 printf("I2C read failed in rtc_validate()\n");
 120                 return 0;
 121         }
 122         /*
 123          * If the OUT bit is "1", there has been a loss of power, so stop the
 124          * oscillator so it can be "kick-started" as per data sheet.
 125          */
 126         if (0x00 != (data[RTC_CTRL] & 0x80)) {
 127                 printf("M41T60 RTC clock lost power.\n");
 128                 data[RTC_SEC] = 0x80;
 129                 if (i2c_write(CFG_I2C_RTC_ADDR, RTC_SEC, 1, data, 1)) {
 130                         printf("I2C write failed in rtc_validate()\n");
 131                         return 0;
 132                 }
 133         }
 134         /*
 135          * If the oscillator is stopped or the date is invalid, then reset the
 136          * OUT bit to "0", reset the date registers, and start the oscillator.
 137          */
 138         min = data[RTC_MIN] & 0x7F;
 139         date = data[RTC_DATE];
 140         month = data[RTC_MONTH] & 0x3F;
 141         years = data[RTC_YEAR];
 142         if (0x59 < data[RTC_SEC] || 0x09 < (data[RTC_SEC] & 0x0F) ||
 143             0x59 < min || 0x09 < (min & 0x0F) ||
 144             0x23 < data[RTC_HOUR] || 0x09 < (data[RTC_HOUR] & 0x0F) ||
 145             0x07 < data[RTC_DAY] || 0x00 == data[RTC_DAY] ||
 146             0x12 < month ||
 147             0x99 < years || 0x09 < (years & 0x0F) ||
 148             daysInMonth[month] < date || 0x09 < (date & 0x0F) || 0x00 == date ||
 149             (0x29 == date && 0x02 == month &&
 150              ((0x00 != (years & 0x03)) ||
 151               (0x00 == years && 0x00 != (data[RTC_MONTH] & 0xC0))))) {
 152                 printf("Resetting M41T60 RTC clock.\n");
 153                 /*
 154                  * Set to 00:00:00 1900-01-01 (Monday)
 155                  */
 156                 data[RTC_SEC] = 0x00;
 157                 data[RTC_MIN] &= 0x80;  /* preserve OFIE bit */
 158                 data[RTC_HOUR] = 0x00;
 159                 data[RTC_DAY] = 0x02;
 160                 data[RTC_DATE] = 0x01;
 161                 data[RTC_MONTH] = 0xC1;
 162                 data[RTC_YEAR] = 0x00;
 163                 data[RTC_CTRL] &= 0x7F; /* reset OUT bit */
 164
 165                 if (i2c_write(CFG_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
 166                         printf("I2C write failed in rtc_validate()\n");
 167                         return 0;
 168                 }
 169         }
 170         return data;
 171 }
 172
 173 int rtc_get(struct rtc_time *tmp)
 174 {
 175         uchar const *const data = rtc_validate();
 176
 177         if (!data)
 178                 return -1;
 179
 180         tmp->tm_sec = bcd2bin(data[RTC_SEC] & 0x7F);
 181         tmp->tm_min = bcd2bin(data[RTC_MIN] & 0x7F);
 182         tmp->tm_hour = bcd2bin(data[RTC_HOUR] & 0x3F);
 183         tmp->tm_mday = bcd2bin(data[RTC_DATE] & 0x3F);
 184         tmp->tm_mon = bcd2bin(data[RTC_MONTH] & 0x1F);
 185         tmp->tm_year = cb2year(data[RTC_MONTH] >> 6) + bcd2bin(data[RTC_YEAR]);
 186         tmp->tm_wday = bcd2bin(data[RTC_DAY] & 0x07) - 1;
 187         tmp->tm_yday = 0;
 188         tmp->tm_isdst = 0;
 189
 190         debug("Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 191               tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
 192               tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
 193
 194         return 0;
 195 }
 196
 197 void rtc_set(struct rtc_time *tmp)
 198 {
 199         uchar *const data = rtc_validate();
 200
 201         if (!data)
 202                 return;
 203
 204         debug("Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 205               tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
 206               tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
 207
 208         data[RTC_SEC] = (data[RTC_SEC] & 0x80) | (bin2bcd(tmp->tm_sec) & 0x7F);
 209         data[RTC_MIN] = (data[RTC_MIN] & 0X80) | (bin2bcd(tmp->tm_min) & 0X7F);
 210         data[RTC_HOUR] = bin2bcd(tmp->tm_hour) & 0x3F;
 211         data[RTC_DATE] = bin2bcd(tmp->tm_mday) & 0x3F;
 212         data[RTC_MONTH] = bin2bcd(tmp->tm_mon) & 0x1F;
 213         data[RTC_YEAR] = bin2bcd(tmp->tm_year % 100);
 214         data[RTC_MONTH] |= year2cb(tmp->tm_year) << 6;
 215         data[RTC_DAY] = bin2bcd(tmp->tm_wday + 1) & 0x07;
 216         if (i2c_write(CFG_I2C_RTC_ADDR, 0, 1, data, RTC_REG_CNT)) {
 217                 printf("I2C write failed in rtc_set()\n");
 218                 return;
 219         }
 220 }
 221
 222 void rtc_reset(void)
 223 {
 224         uchar *const data = rtc_validate();
 225         char const *const s = getenv("rtccal");
 226
 227         if (!data)
 228                 return;
 229
 230         rtc_dump("begin reset");
 231         /*
 232          * If environmental variable "rtccal" is present, it must be a hex value
 233          * between 0x00 and 0x3F, inclusive.  The five least-significan bits
 234          * represent the calibration magnitude, and the sixth bit the sign bit.
 235          * If these do not match the contents of the hardware register, that
 236          * register is updated.  The value 0x00 imples no correction.  Consult
 237          * the M41T60 documentation for further details.
 238          */
 239         if (s) {
 240                 unsigned long const l = simple_strtoul(s, 0, 16);
 241
 242                 if (l <= 0x3F) {
 243                         if ((data[RTC_CTRL] & 0x3F) != l) {
 244                                 printf("Setting RTC calibration to 0x%02X\n",
 245                                        l);
 246                                 data[RTC_CTRL] &= 0xC0;
 247                                 data[RTC_CTRL] |= (uchar) l;
 248                         }
 249                 } else
 250                         printf("environment parameter \"rtccal\" not valid: "
 251                                "ignoring\n");
 252         }
 253         /*
 254          * Turn off frequency test.
 255          */
 256         data[RTC_CTRL] &= 0xBF;
 257         if (i2c_write(CFG_I2C_RTC_ADDR, RTC_CTRL, 1, data + RTC_CTRL, 1)) {
 258                 printf("I2C write failed in rtc_reset()\n");
 259                 return;
 260         }
 261         rtc_dump("end reset");
 262 }
 263 #endif /* CONFIG_RTC_M41T60 && CFG_I2C_RTC_ADDR && CONFIG_CMD_DATE */