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

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2
   3/*
   4 * IBM ASM Service Processor Device Driver
   5 *
   6 * Copyright (C) IBM Corporation, 2004
   7 *
   8 * Author: Max Asböck <amax@us.ibm.com>
   9 */
  10
  11#include <linux/notifier.h>
  12#include <linux/panic_notifier.h>
  13#include "ibmasm.h"
  14#include "dot_command.h"
  15#include "lowlevel.h"
  16
  17static int suspend_heartbeats = 0;
  18
  19/*
  20 * Once the driver indicates to the service processor that it is running
  21 * - see send_os_state() - the service processor sends periodic heartbeats
  22 * to the driver. The driver must respond to the heartbeats or else the OS
  23 * will be rebooted.
  24 * In the case of a panic the interrupt handler continues to work and thus
  25 * continues to respond to heartbeats, making the service processor believe
  26 * the OS is still running and thus preventing a reboot.
  27 * To prevent this from happening a callback is added the panic_notifier_list.
  28 * Before responding to a heartbeat the driver checks if a panic has happened,
  29 * if yes it suspends heartbeat, causing the service processor to reboot as
  30 * expected.
  31 */
  32static int panic_happened(struct notifier_block *n, unsigned long val, void *v)
  33{
  34        suspend_heartbeats = 1;
  35        return 0;
  36}
  37
  38static struct notifier_block panic_notifier = { panic_happened, NULL, 1 };
  39
  40void ibmasm_register_panic_notifier(void)
  41{
  42        atomic_notifier_chain_register(&panic_notifier_list, &panic_notifier);
  43}
  44
  45void ibmasm_unregister_panic_notifier(void)
  46{
  47        atomic_notifier_chain_unregister(&panic_notifier_list,
  48                        &panic_notifier);
  49}
  50
  51
  52int ibmasm_heartbeat_init(struct service_processor *sp)
  53{
  54        sp->heartbeat = ibmasm_new_command(sp, HEARTBEAT_BUFFER_SIZE);
  55        if (sp->heartbeat == NULL)
  56                return -ENOMEM;
  57
  58        return 0;
  59}
  60
  61void ibmasm_heartbeat_exit(struct service_processor *sp)
  62{
  63        char tsbuf[32];
  64
  65        dbg("%s:%d at %s\n", __func__, __LINE__, get_timestamp(tsbuf));
  66        ibmasm_wait_for_response(sp->heartbeat, IBMASM_CMD_TIMEOUT_NORMAL);
  67        dbg("%s:%d at %s\n", __func__, __LINE__, get_timestamp(tsbuf));
  68        suspend_heartbeats = 1;
  69        command_put(sp->heartbeat);
  70}
  71
  72void ibmasm_receive_heartbeat(struct service_processor *sp,  void *message, size_t size)
  73{
  74        struct command *cmd = sp->heartbeat;
  75        struct dot_command_header *header = (struct dot_command_header *)cmd->buffer;
  76        char tsbuf[32];
  77
  78        dbg("%s:%d at %s\n", __func__, __LINE__, get_timestamp(tsbuf));
  79        if (suspend_heartbeats)
  80                return;
  81
  82        /* return the received dot command to sender */
  83        cmd->status = IBMASM_CMD_PENDING;
  84        size = min(size, cmd->buffer_size);
  85        memcpy_fromio(cmd->buffer, message, size);
  86        header->type = sp_write;
  87        ibmasm_exec_command(sp, cmd);
  88}
  89