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
  29 static int suspend_heartbeats = 0;
  30
  31 /*
  32  * Once the driver indicates to the service processor that it is running
  33  * - see send_os_state() - the service processor sends periodic heartbeats
  34  * to the driver. The driver must respond to the heartbeats or else the OS
  35  * will be rebooted.
  36  * In the case of a panic the interrupt handler continues to work and thus
  37  * continues to respond to heartbeats, making the service processor believe
  38  * the OS is still running and thus preventing a reboot.
  39  * To prevent this from happening a callback is added the panic_notifier_list.
  40  * Before responding to a heartbeat the driver checks if a panic has happened,
  41  * if yes it suspends heartbeat, causing the service processor to reboot as
  42  * expected.
  43  */
  44 static int panic_happened(struct notifier_block *n, unsigned long val, void *v)
  45 {
  46         suspend_heartbeats = 1;
  47         return 0;
  48 }
  49
  50 static struct notifier_block panic_notifier = { panic_happened, NULL, 1 };
  51
  52 void ibmasm_register_panic_notifier(void)
  53 {
  54         notifier_chain_register(&panic_notifier_list, &panic_notifier);
  55 }
  56
  57 void ibmasm_unregister_panic_notifier(void)
  58 {
  59         notifier_chain_unregister(&panic_notifier_list, &panic_notifier);
  60 }
  61
  62
  63 int ibmasm_heartbeat_init(struct service_processor *sp)
  64 {
  65         sp->heartbeat = ibmasm_new_command(HEARTBEAT_BUFFER_SIZE);
  66         if (sp->heartbeat == NULL)
  67                 return -ENOMEM;
  68
  69         return 0;
  70 }
  71
  72 void ibmasm_heartbeat_exit(struct service_processor *sp)
  73 {
  74         command_put(sp->heartbeat);
  75 }
  76
  77 void ibmasm_receive_heartbeat(struct service_processor *sp,  void *message, size_t size)
  78 {
  79         struct command *cmd = sp->heartbeat;
  80         struct dot_command_header *header = (struct dot_command_header *)cmd->buffer;
  81
  82         if (suspend_heartbeats)
  83                 return;
  84
  85         /* return the received dot command to sender */
  86         cmd->status = IBMASM_CMD_PENDING;
  87         size = min(size, cmd->buffer_size);
  88         memcpy(cmd->buffer, message, size);
  89         header->type = sp_write;
  90         ibmasm_exec_command(sp, cmd);
  91 }