LXR linux/drivers/misc/ibmasm/heartbeat.c

   1
   2/*
   3 * IBM ASM Service Processor Device Driver
   4 *
   5 * This program is free software; you can redistribute it and/or modify
   6 * it under the terms of the GNU General Public License as published by
   7 * the Free Software Foundation; either version 2 of the License, or
   8 * (at your option) any later version.
   9 *
  10 * This program is distributed in the hope that it will be useful,
  11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 * GNU General Public License for more details.
  14 *
  15 * You should have received a copy of the GNU General Public License
  16 * along with this program; if not, write to the Free Software
  17 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  18 *
  19 * Copyright (C) IBM Corporation, 2004
  20 *
  21 * Author: Max Asböck <amax@us.ibm.com>
  22 *
  23 */
  24
  25#include <linux/notifier.h>
  26#include "ibmasm.h"
  27#include "dot_command.h"
  28#include "lowlevel.h"
  29
  30static int suspend_heartbeats = 0;
  31
  32/*
  33 * Once the driver indicates to the service processor that it is running
  34 * - see send_os_state() - the service processor sends periodic heartbeats
  35 * to the driver. The driver must respond to the heartbeats or else the OS
  36 * will be rebooted.
  37 * In the case of a panic the interrupt handler continues to work and thus
  38 * continues to respond to heartbeats, making the service processor believe
  39 * the OS is still running and thus preventing a reboot.
  40 * To prevent this from happening a callback is added the panic_notifier_list.
  41 * Before responding to a heartbeat the driver checks if a panic has happened,
  42 * if yes it suspends heartbeat, causing the service processor to reboot as
  43 * expected.
  44 */
  45static int panic_happened(struct notifier_block *n, unsigned long val, void *v)
  46{
  47        suspend_heartbeats = 1;
  48        return 0;
  49}
  50
  51static struct notifier_block panic_notifier = { panic_happened, NULL, 1 };
  52
  53void ibmasm_register_panic_notifier(void)
  54{
  55        atomic_notifier_chain_register(&panic_notifier_list, &panic_notifier);
  56}
  57
  58void ibmasm_unregister_panic_notifier(void)
  59{
  60        atomic_notifier_chain_unregister(&panic_notifier_list,
  61                        &panic_notifier);
  62}
  63
  64
  65int ibmasm_heartbeat_init(struct service_processor *sp)
  66{
  67        sp->heartbeat = ibmasm_new_command(sp, HEARTBEAT_BUFFER_SIZE);
  68        if (sp->heartbeat == NULL)
  69                return -ENOMEM;
  70
  71        return 0;
  72}
  73
  74void ibmasm_heartbeat_exit(struct service_processor *sp)
  75{
  76        char tsbuf[32];
  77
  78        dbg("%s:%d at %s\n", __func__, __LINE__, get_timestamp(tsbuf));
  79        ibmasm_wait_for_response(sp->heartbeat, IBMASM_CMD_TIMEOUT_NORMAL);
  80        dbg("%s:%d at %s\n", __func__, __LINE__, get_timestamp(tsbuf));
  81        suspend_heartbeats = 1;
  82        command_put(sp->heartbeat);
  83}
  84
  85void ibmasm_receive_heartbeat(struct service_processor *sp,  void *message, size_t size)
  86{
  87        struct command *cmd = sp->heartbeat;
  88        struct dot_command_header *header = (struct dot_command_header *)cmd->buffer;
  89        char tsbuf[32];
  90
  91        dbg("%s:%d at %s\n", __func__, __LINE__, get_timestamp(tsbuf));
  92        if (suspend_heartbeats)
  93                return;
  94
  95        /* return the received dot command to sender */
  96        cmd->status = IBMASM_CMD_PENDING;
  97        size = min(size, cmd->buffer_size);
  98        memcpy_fromio(cmd->buffer, message, size);
  99        header->type = sp_write;
 100        ibmasm_exec_command(sp, cmd);
 101}
 102