misc/ibmasm/heartbeat.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002
0003 /*
0004  * IBM ASM Service Processor Device Driver
0005  *
0006  * Copyright (C) IBM Corporation, 2004
0007  *
0008  * Author: Max Asböck <amax@us.ibm.com>
0009  */
0010
0011 #include <linux/notifier.h>
0012 #include <linux/panic_notifier.h>
0013 #include "ibmasm.h"
0014 #include "dot_command.h"
0015 #include "lowlevel.h"
0016
0017 static int suspend_heartbeats = 0;
0018
0019 /*
0020  * Once the driver indicates to the service processor that it is running
0021  * - see send_os_state() - the service processor sends periodic heartbeats
0022  * to the driver. The driver must respond to the heartbeats or else the OS
0023  * will be rebooted.
0024  * In the case of a panic the interrupt handler continues to work and thus
0025  * continues to respond to heartbeats, making the service processor believe
0026  * the OS is still running and thus preventing a reboot.
0027  * To prevent this from happening a callback is added the panic_notifier_list.
0028  * Before responding to a heartbeat the driver checks if a panic has happened,
0029  * if yes it suspends heartbeat, causing the service processor to reboot as
0030  * expected.
0031  */
0032 static int panic_happened(struct notifier_block *n, unsigned long val, void *v)
0033 {
0034     suspend_heartbeats = 1;
0035     return 0;
0036 }
0037
0038 static struct notifier_block panic_notifier = { panic_happened, NULL, 1 };
0039
0040 void ibmasm_register_panic_notifier(void)
0041 {
0042     atomic_notifier_chain_register(&panic_notifier_list, &panic_notifier);
0043 }
0044
0045 void ibmasm_unregister_panic_notifier(void)
0046 {
0047     atomic_notifier_chain_unregister(&panic_notifier_list,
0048             &panic_notifier);
0049 }
0050
0051
0052 int ibmasm_heartbeat_init(struct service_processor *sp)
0053 {
0054     sp->heartbeat = ibmasm_new_command(sp, HEARTBEAT_BUFFER_SIZE);
0055     if (sp->heartbeat == NULL)
0056         return -ENOMEM;
0057
0058     return 0;
0059 }
0060
0061 void ibmasm_heartbeat_exit(struct service_processor *sp)
0062 {
0063     char tsbuf[32];
0064
0065     dbg("%s:%d at %s\n", __func__, __LINE__, get_timestamp(tsbuf));
0066     ibmasm_wait_for_response(sp->heartbeat, IBMASM_CMD_TIMEOUT_NORMAL);
0067     dbg("%s:%d at %s\n", __func__, __LINE__, get_timestamp(tsbuf));
0068     suspend_heartbeats = 1;
0069     command_put(sp->heartbeat);
0070 }
0071
0072 void ibmasm_receive_heartbeat(struct service_processor *sp,  void *message, size_t size)
0073 {
0074     struct command *cmd = sp->heartbeat;
0075     struct dot_command_header *header = (struct dot_command_header *)cmd->buffer;
0076     char tsbuf[32];
0077
0078     dbg("%s:%d at %s\n", __func__, __LINE__, get_timestamp(tsbuf));
0079     if (suspend_heartbeats)
0080         return;
0081
0082     /* return the received dot command to sender */
0083     cmd->status = IBMASM_CMD_PENDING;
0084     size = min(size, cmd->buffer_size);
0085     memcpy_fromio(cmd->buffer, message, size);
0086     header->type = sp_write;
0087     ibmasm_exec_command(sp, cmd);
0088 }