The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/dev/dec/mc146818reg.h

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    1 /* $FreeBSD$ */
    2 /*      $NetBSD: mc146818reg.h,v 1.2 1997/03/12 06:53:42 cgd Exp $      */
    3 
    4 /*-
    5  * Copyright (c) 1995 Carnegie-Mellon University.
    6  * All rights reserved.
    7  * 
    8  * Permission to use, copy, modify and distribute this software and
    9  * its documentation is hereby granted, provided that both the copyright
   10  * notice and this permission notice appear in all copies of the
   11  * software, derivative works or modified versions, and any portions
   12  * thereof, and that both notices appear in supporting documentation.
   13  * 
   14  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 
   15  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 
   16  * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
   17  * 
   18  * Carnegie Mellon requests users of this software to return to
   19  *
   20  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
   21  *  School of Computer Science
   22  *  Carnegie Mellon University
   23  *  Pittsburgh PA 15213-3890
   24  *
   25  * any improvements or extensions that they make and grant Carnegie the
   26  * rights to redistribute these changes.
   27  */
   28 
   29 /*
   30  * Definitions for the Motorola MC146818A Real Time Clock.
   31  * They also apply for the (compatible) Dallas Semicontuctor DS1287A RTC.
   32  *
   33  * Though there are undoubtedly other (better) sources, this material was
   34  * culled from the DEC "KN121 System Module Programmer's Reference
   35  * Information."
   36  *
   37  * The MC146818A has 16 registers.  The first 10 contain time-of-year
   38  * and alarm data.  The rest contain various control and status bits.
   39  *
   40  * To read or write the registers, one writes the register number to
   41  * the RTC's control port, then either reads from or writes the new
   42  * data to the RTC's data port.  Since the locations of these ports
   43  * and the method used to access them can be machine-dependent, the
   44  * low-level details of reading and writing the RTC's registers are
   45  * handled by machine-specific functions.
   46  *
   47  * The time-of-year and alarm data can be expressed in either binary
   48  * or BCD, and they are selected by a bit in register B.
   49  *
   50  * The "hour" time-of-year and alarm fields can either be expressed in
   51  * AM/PM format, or in 24-hour format.  If AM/PM format is chosen, the
   52  * hour fields can have the values: 1-12 and 81-92 (the latter being
   53  * PM).  If the 24-hour format is chosen, they can have the values
   54  * 0-24.  The hour format is selectable by a bit in register B.
   55  * (XXX IS AM/PM MODE DESCRIPTION CORRECT?)
   56  *
   57  * It is assumed the if systems are going to use BCD (rather than
   58  * binary) mode, or AM/PM hour format, they'll do the appropriate
   59  * conversions in machine-dependent code.  Also, if the clock is
   60  * switched between BCD and binary mode, or between AM/PM mode and
   61  * 24-hour mode, the time-of-day and alarm registers are NOT
   62  * automatically reset; they must be reprogrammed with correct values.
   63  */
   64 
   65 /*
   66  * The registers, and the bits within each register.
   67  */
   68 
   69 #define MC_SEC          0x0     /* Time of year: seconds (0-59) */
   70 #define MC_ASEC         0x1     /* Alarm: seconds */
   71 #define MC_MIN          0x2     /* Time of year: minutes (0-59) */
   72 #define MC_AMIN         0x3     /* Alarm: minutes */
   73 #define MC_HOUR         0x4     /* Time of year: hour (see above) */
   74 #define MC_AHOUR        0x5     /* Alarm: hour */
   75 #define MC_DOW          0x6     /* Time of year: day of week (1-7) */
   76 #define MC_DOM          0x7     /* Time of year: day of month (1-31) */
   77 #define MC_MONTH        0x8     /* Time of year: month (1-12) */
   78 #define MC_YEAR         0x9     /* Time of year: year in century (0-99) */
   79 
   80 #define MC_REGA         0xa     /* Control register A */
   81 
   82 #define  MC_REGA_RSMASK 0x0f    /* Interrupt rate select mask (see below) */
   83 #define  MC_REGA_DVMASK 0x70    /* Divisor select mask (see below) */
   84 #define  MC_REGA_UIP    0x80    /* Update in progress; read only. */
   85 
   86 #define MC_REGB         0xb     /* Control register B */
   87 
   88 #define  MC_REGB_DSE    0x01    /* Daylight Savings Enable */
   89 #define  MC_REGB_24HR   0x02    /* 24-hour mode (AM/PM mode when clear) */
   90 #define  MC_REGB_BINARY 0x04    /* Binary mode (BCD mode when clear) */
   91 #define  MC_REGB_SQWE   0x08    /* Square Wave Enable */
   92 #define  MC_REGB_UIE    0x10    /* Update End interrupt enable */
   93 #define  MC_REGB_AIE    0x20    /* Alarm interrupt enable */
   94 #define  MC_REGB_PIE    0x40    /* Periodic interrupt enable */
   95 #define  MC_REGB_SET    0x80    /* Allow time to be set; stops updates */
   96 
   97 #define MC_REGC         0xc     /* Control register C */
   98 
   99 /*       MC_REGC_UNUSED 0x0f    UNUSED */
  100 #define  MC_REGC_UF     0x10    /* Update End interrupt flag */
  101 #define  MC_REGC_AF     0x20    /* Alarm interrupt flag */
  102 #define  MC_REGC_PF     0x40    /* Periodic interrupt flag */
  103 #define  MC_REGC_IRQF   0x80    /* Interrupt request pending flag */
  104 
  105 #define MC_REGD         0xd     /* Control register D */
  106 
  107 /*       MC_REGD_UNUSED 0x7f    UNUSED */
  108 #define  MC_REGD_VRT    0x80    /* Valid RAM and Time bit */
  109 
  110 
  111 #define MC_NREGS        0xe     /* 14 registers; CMOS follows */
  112 #define MC_NTODREGS     0xa     /* 10 of those regs are for TOD and alarm */
  113 
  114 #define MC_NVRAM_START  0xe     /* start of NVRAM: offset 14 */
  115 #define MC_NVRAM_SIZE   50      /* 50 bytes of NVRAM */
  116 
  117 /*
  118  * Periodic Interrupt Rate Select constants (Control register A)
  119  */
  120 #define MC_RATE_NONE    0x0     /* No periodic interrupt */
  121 #define MC_RATE_1       0x1     /* 256 Hz if MC_BASE_32_KHz, else 32768 Hz */
  122 #define MC_RATE_2       0x2     /* 128 Hz if MC_BASE_32_KHz, else 16384 Hz */
  123 #define MC_RATE_8192_Hz 0x3     /* 122.070 us period */
  124 #define MC_RATE_4096_Hz 0x4     /* 244.141 us period */
  125 #define MC_RATE_2048_Hz 0x5     /* 488.281 us period */
  126 #define MC_RATE_1024_Hz 0x6     /* 976.562 us period */
  127 #define MC_RATE_512_Hz  0x7     /* 1.953125 ms period */
  128 #define MC_RATE_256_Hz  0x8     /* 3.90625 ms period */
  129 #define MC_RATE_128_Hz  0x9     /* 7.8125 ms period */
  130 #define MC_RATE_64_Hz   0xa     /* 15.625 ms period */
  131 #define MC_RATE_32_Hz   0xb     /* 31.25 ms period */
  132 #define MC_RATE_16_Hz   0xc     /* 62.5 ms period */
  133 #define MC_RATE_8_Hz    0xd     /* 125 ms period */
  134 #define MC_RATE_4_Hz    0xe     /* 250 ms period */
  135 #define MC_RATE_2_Hz    0xf     /* 500 ms period */
  136 
  137 /*
  138  * Time base (divisor select) constants (Control register A)
  139  */
  140 #define MC_BASE_4_MHz   0x00            /* 4MHz crystal */
  141 #define MC_BASE_1_MHz   0x10            /* 1MHz crystal */
  142 #define MC_BASE_32_KHz  0x20            /* 32KHz crystal */
  143 #define MC_BASE_NONE    0x60            /* actually, both of these reset */
  144 #define MC_BASE_RESET   0x70
  145 
  146 /*
  147  * A collection of TOD/Alarm registers.
  148  */
  149 typedef u_int mc_todregs[MC_NTODREGS];
  150 
  151 /*
  152  * Get all of the TOD/Alarm registers
  153  * Must be called at splhigh(), and with the RTC properly set up.
  154  */
  155 #define MC146818_GETTOD(dev, regs)                                      \
  156         do {                                                            \
  157                 int i;                                                  \
  158                                                                         \
  159                 /* update in progress; spin loop */                     \
  160                 while (MCCLOCK_READ(dev, MC_REGA) & MC_REGA_UIP)        \
  161                         ;                                               \
  162                                                                         \
  163                 /* read all of the tod/alarm regs */                    \
  164                 for (i = 0; i < MC_NTODREGS; i++)                       \
  165                         (*regs)[i] = MCCLOCK_READ(dev, i);              \
  166         } while (0);
  167 
  168 /*
  169  * Set all of the TOD/Alarm registers
  170  * Must be called at splhigh(), and with the RTC properly set up.
  171  */
  172 #define MC146818_PUTTOD(dev, regs)                                      \
  173         do {                                                            \
  174                 int i;                                                  \
  175                                                                         \
  176                 /* stop updates while setting */                        \
  177                 MCCLOCK_WRITE(dev, MC_REGB,                             \
  178                     MCCLOCK_READ(dev, MC_REGB) | MC_REGB_SET);          \
  179                                                                         \
  180                 /* write all of the tod/alarm regs */                   \
  181                 for (i = 0; i < MC_NTODREGS; i++)                       \
  182                         MCCLOCK_WRITE(dev, i, (*regs)[i]);              \
  183                                                                         \
  184                 /* reenable updates */                                  \
  185                 MCCLOCK_WRITE(dev, MC_REGB,                             \
  186                     MCCLOCK_READ(dev, MC_REGB) & ~MC_REGB_SET);         \
  187         } while (0);

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