linux/drivers/misc/ibmasm/heartbeat.c

// SPDX-License-Identifier: GPL-2.0-or-later

/*
 * IBM ASM Service Processor Device Driver
 *
 * Copyright (C) IBM Corporation, 2004
 *
 * Author: Max Asböck <[email protected]>
 */

#include <linux/notifier.h>
#include <linux/panic_notifier.h>
#include "ibmasm.h"
#include "dot_command.h"
#include "lowlevel.h"

static int suspend_heartbeats = …;

/*
 * Once the driver indicates to the service processor that it is running
 * - see send_os_state() - the service processor sends periodic heartbeats
 * to the driver. The driver must respond to the heartbeats or else the OS
 * will be rebooted.
 * In the case of a panic the interrupt handler continues to work and thus
 * continues to respond to heartbeats, making the service processor believe
 * the OS is still running and thus preventing a reboot.
 * To prevent this from happening a callback is added the panic_notifier_list.
 * Before responding to a heartbeat the driver checks if a panic has happened,
 * if yes it suspends heartbeat, causing the service processor to reboot as
 * expected.
 */
static int panic_happened(struct notifier_block *n, unsigned long val, void *v)
{ … }

static struct notifier_block panic_notifier = …;

void ibmasm_register_panic_notifier(void)
{ … }

void ibmasm_unregister_panic_notifier(void)
{ … }


int ibmasm_heartbeat_init(struct service_processor *sp)
{ … }

void ibmasm_heartbeat_exit(struct service_processor *sp)
{ … }

void ibmasm_receive_heartbeat(struct service_processor *sp,  void *message, size_t size)
{ … }