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  * SPDX-License-Identifier:     GPL-2.0+
  11  */
  12
  13 /*
  14  * STMicroelectronics M41T60 serial access real-time clock
  15  */
  16
  17 /* #define DEBUG 1 */
  18
  19 #include <common.h>
  20 #include <command.h>
  21 #include <rtc.h>
  22 #include <i2c.h>
  23
  24 #if defined(CONFIG_SYS_I2C_RTC_ADDR) && defined(CONFIG_CMD_DATE)
  25
  26 /*
  27  * Convert between century and "century bits" (CB1 and CB0).  These routines
  28  * assume years are in the range 1900 - 2299.
  29  */
  30
  31 static unsigned char year2cb(unsigned const year)
  32 {
  33         if (year < 1900 || year >= 2300)
  34                 printf("M41T60 RTC: year %d out of range\n", year);
  35
  36         return (year / 100) & 0x3;
  37 }
  38
  39 static unsigned cb2year(unsigned const cb)
  40 {
  41         return 1900 + 100 * ((cb + 1) & 0x3);
  42 }
  43
  44 /*
  45  * These are simple defines for the chip local to here so they aren't too
  46  * verbose.  DAY/DATE aren't nice but that is how they are on the data sheet.
  47  */
  48 #define RTC_SEC         0x0
  49 #define RTC_MIN         0x1
  50 #define RTC_HOUR        0x2
  51 #define RTC_DAY         0x3
  52 #define RTC_DATE        0x4
  53 #define RTC_MONTH       0x5
  54 #define RTC_YEAR        0x6
  55
  56 #define RTC_REG_CNT     7
  57
  58 #define RTC_CTRL        0x7
  59
  60 #if defined(DEBUG)
  61 static void rtc_dump(char const *const label)
  62 {
  63         uchar data[8];
  64
  65         if (i2c_read(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
  66                 printf("I2C read failed in rtc_dump()\n");
  67                 return;
  68         }
  69         printf("RTC dump %s: %02X-%02X-%02X-%02X-%02X-%02X-%02X-%02X\n",
  70                label, data[0], data[1], data[2], data[3],
  71                data[4], data[5], data[6], data[7]);
  72 }
  73 #else
  74 #define rtc_dump(label)
  75 #endif
  76
  77 static uchar *rtc_validate(void)
  78 {
  79         /*
  80          * This routine uses the OUT bit and the validity of the time values to
  81          * determine whether there has been an initial power-up since the last
  82          * time the routine was run.  It assumes that the OUT bit is not being
  83          * used for any other purpose.
  84          */
  85         static const uchar daysInMonth[0x13] = {
  86                 0x00, 0x31, 0x29, 0x31, 0x30, 0x31, 0x30, 0x31,
  87                 0x31, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  88                 0x31, 0x30, 0x31
  89         };
  90         static uchar data[8];
  91         uchar min, date, month, years;
  92
  93         rtc_dump("begin validate");
  94         if (i2c_read(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
  95                 printf("I2C read failed in rtc_validate()\n");
  96                 return 0;
  97         }
  98         /*
  99          * If the OUT bit is "1", there has been a loss of power, so stop the
 100          * oscillator so it can be "kick-started" as per data sheet.
 101          */
 102         if (0x00 != (data[RTC_CTRL] & 0x80)) {
 103                 printf("M41T60 RTC clock lost power.\n");
 104                 data[RTC_SEC] = 0x80;
 105                 if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, RTC_SEC, 1, data, 1)) {
 106                         printf("I2C write failed in rtc_validate()\n");
 107                         return 0;
 108                 }
 109         }
 110         /*
 111          * If the oscillator is stopped or the date is invalid, then reset the
 112          * OUT bit to "0", reset the date registers, and start the oscillator.
 113          */
 114         min = data[RTC_MIN] & 0x7F;
 115         date = data[RTC_DATE];
 116         month = data[RTC_MONTH] & 0x3F;
 117         years = data[RTC_YEAR];
 118         if (0x59 < data[RTC_SEC] || 0x09 < (data[RTC_SEC] & 0x0F) ||
 119             0x59 < min || 0x09 < (min & 0x0F) ||
 120             0x23 < data[RTC_HOUR] || 0x09 < (data[RTC_HOUR] & 0x0F) ||
 121             0x07 < data[RTC_DAY] || 0x00 == data[RTC_DAY] ||
 122             0x12 < month ||
 123             0x99 < years || 0x09 < (years & 0x0F) ||
 124             daysInMonth[month] < date || 0x09 < (date & 0x0F) || 0x00 == date ||
 125             (0x29 == date && 0x02 == month &&
 126              ((0x00 != (years & 0x03)) ||
 127               (0x00 == years && 0x00 != (data[RTC_MONTH] & 0xC0))))) {
 128                 printf("Resetting M41T60 RTC clock.\n");
 129                 /*
 130                  * Set to 00:00:00 1900-01-01 (Monday)
 131                  */
 132                 data[RTC_SEC] = 0x00;
 133                 data[RTC_MIN] &= 0x80;  /* preserve OFIE bit */
 134                 data[RTC_HOUR] = 0x00;
 135                 data[RTC_DAY] = 0x02;
 136                 data[RTC_DATE] = 0x01;
 137                 data[RTC_MONTH] = 0xC1;
 138                 data[RTC_YEAR] = 0x00;
 139                 data[RTC_CTRL] &= 0x7F; /* reset OUT bit */
 140
 141                 if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
 142                         printf("I2C write failed in rtc_validate()\n");
 143                         return 0;
 144                 }
 145         }
 146         return data;
 147 }
 148
 149 int rtc_get(struct rtc_time *tmp)
 150 {
 151         uchar const *const data = rtc_validate();
 152
 153         if (!data)
 154                 return -1;
 155
 156         tmp->tm_sec = bcd2bin(data[RTC_SEC] & 0x7F);
 157         tmp->tm_min = bcd2bin(data[RTC_MIN] & 0x7F);
 158         tmp->tm_hour = bcd2bin(data[RTC_HOUR] & 0x3F);
 159         tmp->tm_mday = bcd2bin(data[RTC_DATE] & 0x3F);
 160         tmp->tm_mon = bcd2bin(data[RTC_MONTH] & 0x1F);
 161         tmp->tm_year = cb2year(data[RTC_MONTH] >> 6) + bcd2bin(data[RTC_YEAR]);
 162         tmp->tm_wday = bcd2bin(data[RTC_DAY] & 0x07) - 1;
 163         tmp->tm_yday = 0;
 164         tmp->tm_isdst = 0;
 165
 166         debug("Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 167               tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
 168               tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
 169
 170         return 0;
 171 }
 172
 173 int rtc_set(struct rtc_time *tmp)
 174 {
 175         uchar *const data = rtc_validate();
 176
 177         if (!data)
 178                 return -1;
 179
 180         debug("Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 181               tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
 182               tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
 183
 184         data[RTC_SEC] = (data[RTC_SEC] & 0x80) | (bin2bcd(tmp->tm_sec) & 0x7F);
 185         data[RTC_MIN] = (data[RTC_MIN] & 0X80) | (bin2bcd(tmp->tm_min) & 0X7F);
 186         data[RTC_HOUR] = bin2bcd(tmp->tm_hour) & 0x3F;
 187         data[RTC_DATE] = bin2bcd(tmp->tm_mday) & 0x3F;
 188         data[RTC_MONTH] = bin2bcd(tmp->tm_mon) & 0x1F;
 189         data[RTC_YEAR] = bin2bcd(tmp->tm_year % 100);
 190         data[RTC_MONTH] |= year2cb(tmp->tm_year) << 6;
 191         data[RTC_DAY] = bin2bcd(tmp->tm_wday + 1) & 0x07;
 192         if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, RTC_REG_CNT)) {
 193                 printf("I2C write failed in rtc_set()\n");
 194                 return -1;
 195         }
 196
 197         return 0;
 198 }
 199
 200 void rtc_reset(void)
 201 {
 202         uchar *const data = rtc_validate();
 203         char const *const s = env_get("rtccal");
 204
 205         if (!data)
 206                 return;
 207
 208         rtc_dump("begin reset");
 209         /*
 210          * If environmental variable "rtccal" is present, it must be a hex value
 211          * between 0x00 and 0x3F, inclusive.  The five least-significan bits
 212          * represent the calibration magnitude, and the sixth bit the sign bit.
 213          * If these do not match the contents of the hardware register, that
 214          * register is updated.  The value 0x00 imples no correction.  Consult
 215          * the M41T60 documentation for further details.
 216          */
 217         if (s) {
 218                 unsigned long const l = simple_strtoul(s, 0, 16);
 219
 220                 if (l <= 0x3F) {
 221                         if ((data[RTC_CTRL] & 0x3F) != l) {
 222                                 printf("Setting RTC calibration to 0x%02lX\n",
 223                                        l);
 224                                 data[RTC_CTRL] &= 0xC0;
 225                                 data[RTC_CTRL] |= (uchar) l;
 226                         }
 227                 } else
 228                         printf("environment parameter \"rtccal\" not valid: "
 229                                "ignoring\n");
 230         }
 231         /*
 232          * Turn off frequency test.
 233          */
 234         data[RTC_CTRL] &= 0xBF;
 235         if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, RTC_CTRL, 1, data + RTC_CTRL, 1)) {
 236                 printf("I2C write failed in rtc_reset()\n");
 237                 return;
 238         }
 239         rtc_dump("end reset");
 240 }
 241 #endif /* CONFIG_RTC_M41T60 && CONFIG_SYS_I2C_RTC_ADDR && CONFIG_CMD_DATE */