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 
17 static 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  */
panic_happened(struct notifier_block * n,unsigned long val,void * v)32 static int panic_happened(struct notifier_block *n, unsigned long val, void *v)
33 {
34 	suspend_heartbeats = 1;
35 	return 0;
36 }
37 
38 static struct notifier_block panic_notifier = { panic_happened, NULL, 1 };
39 
ibmasm_register_panic_notifier(void)40 void ibmasm_register_panic_notifier(void)
41 {
42 	atomic_notifier_chain_register(&panic_notifier_list, &panic_notifier);
43 }
44 
ibmasm_unregister_panic_notifier(void)45 void ibmasm_unregister_panic_notifier(void)
46 {
47 	atomic_notifier_chain_unregister(&panic_notifier_list,
48 			&panic_notifier);
49 }
50 
51 
ibmasm_heartbeat_init(struct service_processor * sp)52 int 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 
ibmasm_heartbeat_exit(struct service_processor * sp)61 void 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 
ibmasm_receive_heartbeat(struct service_processor * sp,void * message,size_t size)72 void 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