usr/src/uts/sun4u/sys/todsg.h

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright (c) 2000 by Sun Microsystems, Inc.
  24  * All rights reserved.
  25  */
  26
  27 #ifndef _TODSG_H
  28 #define _TODSG_H
  29
  30 #pragma ident   "%Z%%M% %I%     %E% SMI"
  31
  32 #ifdef __cplusplus
  33 extern "C" {
  34 #endif
  35
  36 /*
  37  * Serengeti TOD (time of day) driver
  38  *
  39  * Serengeti does not have hardware TOD chip inside chassis. SC has
  40  * a hardware TOD chip and maintains virtual TOD information for
  41  * each domain. Domain accesses virtual TOD through SRAM on chosen
  42  * IO board.
  43  */
  44
  45 #include <sys/time_impl.h>
  46
  47 /*
  48  * IOSRAM used by virtual TOD
  49  *
  50  * +-------------------------------+
  51  * |       tod_magic               |
  52  * +-------------------------------+
  53  * |       tod_version             |
  54  * +-------------------------------+
  55  * |       tod_get_value           |
  56  * +-------------------------------+
  57  * |       tod_domain_skew         |
  58  * +-------------------------------+
  59  * |       tod_reserved            |
  60  * +-------------------------------+
  61  * |       tod_i_am_alive          |
  62  * +-------------------------------+
  63  * |       tod_timeout_period      |
  64  * +-------------------------------+
  65  *
  66  * For every struct member in IOSRAM except tod_domain_skew and tod_reserved,
  67  * there are only one writer and one reader.
  68  * tod_reserved (was tod_set_flag) is for backwards compatibility.
  69  *
  70  *                      reader  read interval    writer  write interval
  71  * ------------------------------------------------------------------------
  72  * tod_get_value        Solaris 1 second         SC      twice per second
  73  * tod_domain_skew      Solaris 1 second         Solaris when needed
  74  *                      SC (see following NOTE)
  75  * tod_i_am_alive       SC      twice per second Solaris 1 second
  76  * tod_timeout_period   SC      twice per second Solaris when needed
  77  *
  78  * NOTE: SC reads tod_domain_skew twice per second, notices if it
  79  *       changes, and always keeps the last observed value preserved
  80  *       in non-volatile storage.
  81  */
  82 typedef struct _tod_iosram {
  83         uint32_t tod_magic;     /* magic number, always TODSG_MAGIC     */
  84         uint32_t tod_version;   /* version number                       */
  85         time_t tod_get_value;   /* SC updates and Solaris reads         */
  86         time_t tod_domain_skew; /* Solaris updates and read             */
  87         uint32_t tod_reserved;  /* Was tod_set_flag. No use             */
  88         uint32_t tod_i_am_alive;        /* I'm alive! a.k.a. heartbeat  */
  89         uint32_t tod_timeout_period;    /* time period to decide hard hang */
  90 } tod_iosram_t;
  91
  92 #define TODSG_MAGIC     0x54443100      /* 'T','D', '1', \0 */
  93 #define TODSG_VERSION_1 1
  94
  95 extern int todsg_use_sc;
  96
  97 #ifdef __cplusplus
  98 }
  99 #endif
 100
 101 #endif /* _TODSG_H */