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