board/bmw/m48t59y.c

   1 /*
   2  * SGS M48-T59Y TOD/NVRAM Driver
   3  *
   4  * (C) Copyright 2000
   5  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   6  *
   7  * (C) Copyright 1999, by Curt McDowell, 08-06-99, Broadcom Corp.
   8  *
   9  * (C) Copyright 2001, James Dougherty, 07/18/01, Broadcom Corp.
  10  *
  11  * See file CREDITS for list of people who contributed to this
  12  * project.
  13  *
  14  * This program is free software; you can redistribute it and/or
  15  * modify it under the terms of the GNU General Public License as
  16  * published by the Free Software Foundation; either version 2 of
  17  * the License, or (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with this program; if not, write to the Free Software
  26  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  27  * MA 02111-1307 USA
  28  */
  29
  30 /*
  31  * SGS M48-T59Y TOD/NVRAM Driver
  32  *
  33  * The SGS M48 an 8K NVRAM starting at offset M48_BASE_ADDR and
  34  * continuing for 8176 bytes. After that starts the Time-Of-Day (TOD)
  35  * registers which are used to set/get the internal date/time functions.
  36  *
  37  * This module implements Y2K compliance by taking full year numbers
  38  * and translating back and forth from the TOD 2-digit year.
  39  *
  40  * NOTE: for proper interaction with an operating system, the TOD should
  41  * be used to store Universal Coordinated Time (GMT) and timezone
  42  * conversions should be used.
  43  *
  44  * Here is a diagram of the memory layout:
  45  *
  46  * +---------------------------------------------+ 0xffe0a000
  47  * | Non-volatile memory                         | .
  48  * |                                             | .
  49  * | (8176 bytes of Non-volatile memory)         | .
  50  * |                                             | .
  51  * +---------------------------------------------+ 0xffe0bff0
  52  * | Flags                                       |
  53  * +---------------------------------------------+ 0xffe0bff1
  54  * | Unused                                      |
  55  * +---------------------------------------------+ 0xffe0bff2
  56  * | Alarm Seconds                               |
  57  * +---------------------------------------------+ 0xffe0bff3
  58  * | Alarm Minutes                               |
  59  * +---------------------------------------------+ 0xffe0bff4
  60  * | Alarm Date                                  |
  61  * +---------------------------------------------+ 0xffe0bff5
  62  * | Interrupts                                  |
  63  * +---------------------------------------------+ 0xffe0bff6
  64  * | WatchDog                                    |
  65  * +---------------------------------------------+ 0xffe0bff7
  66  * | Calibration                                 |
  67  * +---------------------------------------------+ 0xffe0bff8
  68  * | Seconds                                     |
  69  * +---------------------------------------------+ 0xffe0bff9
  70  * | Minutes                                     |
  71  * +---------------------------------------------+ 0xffe0bffa
  72  * | Hours                                       |
  73  * +---------------------------------------------+ 0xffe0bffb
  74  * | Day                                         |
  75  * +---------------------------------------------+ 0xffe0bffc
  76  * | Date                                        |
  77  * +---------------------------------------------+ 0xffe0bffd
  78  * | Month                                       |
  79  * +---------------------------------------------+ 0xffe0bffe
  80  * | Year (2 digits only)                        |
  81  * +---------------------------------------------+ 0xffe0bfff
  82  */
  83 #include <common.h>
  84 #include <rtc.h>
  85 #include "bmw.h"
  86
  87 /*
  88  * Imported from mousse.h:
  89  *
  90  *   TOD_REG_BASE               Base of m48t59y TOD registers
  91  *   SYS_TOD_UNPROTECT()        Disable NVRAM write protect
  92  *   SYS_TOD_PROTECT()          Re-enable NVRAM write protect
  93  */
  94
  95 #define YEAR            0xf
  96 #define MONTH           0xe
  97 #define DAY             0xd
  98 #define DAY_OF_WEEK     0xc
  99 #define HOUR            0xb
 100 #define MINUTE          0xa
 101 #define SECOND          0x9
 102 #define CONTROL         0x8
 103 #define WATCH           0x7
 104 #define INTCTL          0x6
 105 #define WD_DATE         0x5
 106 #define WD_HOUR         0x4
 107 #define WD_MIN          0x3
 108 #define WD_SEC          0x2
 109 #define _UNUSED         0x1
 110 #define FLAGS           0x0
 111
 112 #define M48_ADDR        ((volatile unsigned char *) TOD_REG_BASE)
 113
 114 int m48_tod_init(void)
 115 {
 116     SYS_TOD_UNPROTECT();
 117
 118     M48_ADDR[CONTROL] = 0;
 119     M48_ADDR[WATCH] = 0;
 120     M48_ADDR[INTCTL] = 0;
 121
 122     /*
 123      * If the oscillator is currently stopped (as on a new part shipped
 124      * from the factory), start it running.
 125      *
 126      * Here is an example of the TOD bytes on a brand new M48T59Y part:
 127      *          00 00 00 00 00 00 00 00 00 88 8c c3 bf c8 f5 01
 128      */
 129
 130     if (M48_ADDR[SECOND] & 0x80)
 131         M48_ADDR[SECOND] = 0;
 132
 133     /* Is battery low */
 134     if ( M48_ADDR[FLAGS] & 0x10) {
 135          printf("NOTICE: Battery low on Real-Time Clock (replace SNAPHAT).\n");
 136     }
 137
 138     SYS_TOD_PROTECT();
 139
 140     return 0;
 141 }
 142
 143 /*
 144  * m48_tod_set
 145  */
 146
 147 static int to_bcd(int value)
 148 {
 149     return value / 10 * 16 + value % 10;
 150 }
 151
 152 static int from_bcd(int value)
 153 {
 154     return value / 16 * 10 + value % 16;
 155 }
 156
 157 static int day_of_week(int y, int m, int d)     /* 0-6 ==> Sun-Sat */
 158 {
 159     static int t[] = {0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4};
 160     y -= m < 3;
 161     return (y + y/4 - y/100 + y/400 + t[m-1] + d) % 7;
 162 }
 163
 164 /*
 165  * Note: the TOD should store the current GMT
 166  */
 167
 168 int m48_tod_set(int year,               /* 1980-2079 */
 169                 int month,              /* 01-12 */
 170                 int day,                /* 01-31 */
 171                 int hour,               /* 00-23 */
 172                 int minute,             /* 00-59 */
 173                 int second)             /* 00-59 */
 174
 175 {
 176     SYS_TOD_UNPROTECT();
 177
 178     M48_ADDR[CONTROL] |= 0x80;  /* Set WRITE bit */
 179
 180     M48_ADDR[YEAR] = to_bcd(year % 100);
 181     M48_ADDR[MONTH] = to_bcd(month);
 182     M48_ADDR[DAY] = to_bcd(day);
 183     M48_ADDR[DAY_OF_WEEK] = day_of_week(year, month, day) + 1;
 184     M48_ADDR[HOUR] = to_bcd(hour);
 185     M48_ADDR[MINUTE] = to_bcd(minute);
 186     M48_ADDR[SECOND] = to_bcd(second);
 187
 188     M48_ADDR[CONTROL] &= ~0x80; /* Clear WRITE bit */
 189
 190     SYS_TOD_PROTECT();
 191
 192     return 0;
 193 }
 194
 195 /*
 196  * Note: the TOD should store the current GMT
 197  */
 198
 199 int m48_tod_get(int *year,              /* 1980-2079 */
 200                 int *month,             /* 01-12 */
 201                 int *day,               /* 01-31 */
 202                 int *hour,              /* 00-23 */
 203                 int *minute,            /* 00-59 */
 204                 int *second)            /* 00-59 */
 205 {
 206     int y;
 207
 208     SYS_TOD_UNPROTECT();
 209
 210     M48_ADDR[CONTROL] |= 0x40;  /* Set READ bit */
 211
 212     y = from_bcd(M48_ADDR[YEAR]);
 213     *year = y < 80 ? 2000 + y : 1900 + y;
 214     *month = from_bcd(M48_ADDR[MONTH]);
 215     *day = from_bcd(M48_ADDR[DAY]);
 216     /* day_of_week = M48_ADDR[DAY_OF_WEEK] & 0xf; */
 217     *hour = from_bcd(M48_ADDR[HOUR]);
 218     *minute = from_bcd(M48_ADDR[MINUTE]);
 219     *second = from_bcd(M48_ADDR[SECOND] & 0x7f);
 220
 221     M48_ADDR[CONTROL] &= ~0x40; /* Clear READ bit */
 222
 223     SYS_TOD_PROTECT();
 224
 225     return 0;
 226 }
 227
 228 int m48_tod_get_second(void)
 229 {
 230     return from_bcd(M48_ADDR[SECOND] & 0x7f);
 231 }
 232
 233 /*
 234  * Watchdog function
 235  *
 236  *  If usec is 0, the watchdog timer is disarmed.
 237  *
 238  *  If usec is non-zero, the watchdog timer is armed (or re-armed) for
 239  *    approximately usec microseconds (if the exact requested usec is
 240  *    not supported by the chip, the next higher available value is used).
 241  *
 242  *  Minimum watchdog timeout = 62500 usec
 243  *  Maximum watchdog timeout = 124 sec (124000000 usec)
 244  */
 245
 246 void m48_watchdog_arm(int usec)
 247 {
 248     int         mpy, res;
 249
 250     SYS_TOD_UNPROTECT();
 251
 252     if (usec == 0) {
 253         res = 0;
 254         mpy = 0;
 255     } else if (usec < 2000000) {        /* Resolution: 1/16s if below 2s */
 256         res = 0;
 257         mpy = (usec + 62499) / 62500;
 258     } else if (usec < 8000000) {        /* Resolution: 1/4s if below 8s */
 259         res = 1;
 260         mpy = (usec + 249999) / 250000;
 261     } else if (usec < 32000000) {       /* Resolution: 1s if below 32s */
 262         res = 2;
 263         mpy = (usec + 999999) / 1000000;
 264     } else {                            /* Resolution: 4s up to 124s */
 265         res = 3;
 266         mpy = (usec + 3999999) / 4000000;
 267         if (mpy > 31)
 268             mpy = 31;
 269     }
 270
 271     M48_ADDR[WATCH] = (0x80 |           /* Steer to RST signal (IRQ = N/C) */
 272                        mpy << 2 |
 273                        res);
 274
 275     SYS_TOD_PROTECT();
 276 }
 277
 278 /*
 279  * U-Boot RTC support.
 280  */
 281 void
 282 rtc_get( struct rtc_time *tmp )
 283 {
 284         m48_tod_get(&tmp->tm_year,
 285                     &tmp->tm_mon,
 286                     &tmp->tm_mday,
 287                     &tmp->tm_hour,
 288                     &tmp->tm_min,
 289                     &tmp->tm_sec);
 290         tmp->tm_yday = 0;
 291         tmp->tm_isdst= 0;
 292
 293 #ifdef RTC_DEBUG
 294         printf( "Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 295                 tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
 296                 tmp->tm_hour, tmp->tm_min, tmp->tm_sec );
 297 #endif
 298 }
 299
 300 void
 301 rtc_set( struct rtc_time *tmp )
 302 {
 303         m48_tod_set(tmp->tm_year,               /* 1980-2079 */
 304                     tmp->tm_mon,                /* 01-12 */
 305                     tmp->tm_mday,              /* 01-31 */
 306                     tmp->tm_hour,               /* 00-23 */
 307                     tmp->tm_min,                /* 00-59 */
 308                     tmp->tm_sec);               /* 00-59 */
 309
 310 #ifdef RTC_DEBUG
 311         printf( "Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 312                 tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
 313                 tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
 314 #endif
 315
 316 }
 317
 318 void
 319 rtc_reset (void)
 320 {
 321   m48_tod_init();
 322 }