xref: /openbmc/linux/drivers/misc/ibmasm/event.c (revision 22246614)
1 
2 /*
3  * IBM ASM Service Processor Device Driver
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License as published by
7  * the Free Software Foundation; either version 2 of the License, or
8  * (at your option) any later version.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  * GNU General Public License for more details.
14  *
15  * You should have received a copy of the GNU General Public License
16  * along with this program; if not, write to the Free Software
17  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
18  *
19  * Copyright (C) IBM Corporation, 2004
20  *
21  * Author: Max Asb�ck <amax@us.ibm.com>
22  *
23  */
24 
25 #include "ibmasm.h"
26 #include "lowlevel.h"
27 
28 /*
29  * ASM service processor event handling routines.
30  *
31  * Events are signalled to the device drivers through interrupts.
32  * They have the format of dot commands, with the type field set to
33  * sp_event.
34  * The driver does not interpret the events, it simply stores them in a
35  * circular buffer.
36  */
37 
38 static void wake_up_event_readers(struct service_processor *sp)
39 {
40 	struct event_reader *reader;
41 
42 	list_for_each_entry(reader, &sp->event_buffer->readers, node)
43                 wake_up_interruptible(&reader->wait);
44 }
45 
46 /**
47  * receive_event
48  * Called by the interrupt handler when a dot command of type sp_event is
49  * received.
50  * Store the event in the circular event buffer, wake up any sleeping
51  * event readers.
52  * There is no reader marker in the buffer, therefore readers are
53  * responsible for keeping up with the writer, or they will loose events.
54  */
55 void ibmasm_receive_event(struct service_processor *sp, void *data, unsigned int data_size)
56 {
57 	struct event_buffer *buffer = sp->event_buffer;
58 	struct ibmasm_event *event;
59 	unsigned long flags;
60 
61 	data_size = min(data_size, IBMASM_EVENT_MAX_SIZE);
62 
63 	spin_lock_irqsave(&sp->lock, flags);
64 	/* copy the event into the next slot in the circular buffer */
65 	event = &buffer->events[buffer->next_index];
66 	memcpy_fromio(event->data, data, data_size);
67 	event->data_size = data_size;
68 	event->serial_number = buffer->next_serial_number;
69 
70 	/* advance indices in the buffer */
71 	buffer->next_index = (buffer->next_index + 1) % IBMASM_NUM_EVENTS;
72 	buffer->next_serial_number++;
73 	spin_unlock_irqrestore(&sp->lock, flags);
74 
75 	wake_up_event_readers(sp);
76 }
77 
78 static inline int event_available(struct event_buffer *b, struct event_reader *r)
79 {
80 	return (r->next_serial_number < b->next_serial_number);
81 }
82 
83 /**
84  * get_next_event
85  * Called by event readers (initiated from user space through the file
86  * system).
87  * Sleeps until a new event is available.
88  */
89 int ibmasm_get_next_event(struct service_processor *sp, struct event_reader *reader)
90 {
91 	struct event_buffer *buffer = sp->event_buffer;
92 	struct ibmasm_event *event;
93 	unsigned int index;
94 	unsigned long flags;
95 
96 	reader->cancelled = 0;
97 
98 	if (wait_event_interruptible(reader->wait,
99 			event_available(buffer, reader) || reader->cancelled))
100 		return -ERESTARTSYS;
101 
102 	if (!event_available(buffer, reader))
103 		return 0;
104 
105 	spin_lock_irqsave(&sp->lock, flags);
106 
107 	index = buffer->next_index;
108 	event = &buffer->events[index];
109 	while (event->serial_number < reader->next_serial_number) {
110 		index = (index + 1) % IBMASM_NUM_EVENTS;
111 		event = &buffer->events[index];
112 	}
113 	memcpy(reader->data, event->data, event->data_size);
114 	reader->data_size = event->data_size;
115 	reader->next_serial_number = event->serial_number + 1;
116 
117 	spin_unlock_irqrestore(&sp->lock, flags);
118 
119 	return event->data_size;
120 }
121 
122 void ibmasm_cancel_next_event(struct event_reader *reader)
123 {
124         reader->cancelled = 1;
125         wake_up_interruptible(&reader->wait);
126 }
127 
128 void ibmasm_event_reader_register(struct service_processor *sp, struct event_reader *reader)
129 {
130 	unsigned long flags;
131 
132 	reader->next_serial_number = sp->event_buffer->next_serial_number;
133 	init_waitqueue_head(&reader->wait);
134 	spin_lock_irqsave(&sp->lock, flags);
135 	list_add(&reader->node, &sp->event_buffer->readers);
136 	spin_unlock_irqrestore(&sp->lock, flags);
137 }
138 
139 void ibmasm_event_reader_unregister(struct service_processor *sp, struct event_reader *reader)
140 {
141 	unsigned long flags;
142 
143 	spin_lock_irqsave(&sp->lock, flags);
144 	list_del(&reader->node);
145 	spin_unlock_irqrestore(&sp->lock, flags);
146 }
147 
148 int ibmasm_event_buffer_init(struct service_processor *sp)
149 {
150 	struct event_buffer *buffer;
151 	struct ibmasm_event *event;
152 	int i;
153 
154 	buffer = kmalloc(sizeof(struct event_buffer), GFP_KERNEL);
155 	if (!buffer)
156 		return 1;
157 
158 	buffer->next_index = 0;
159 	buffer->next_serial_number = 1;
160 
161 	event = buffer->events;
162 	for (i=0; i<IBMASM_NUM_EVENTS; i++, event++)
163 		event->serial_number = 0;
164 
165 	INIT_LIST_HEAD(&buffer->readers);
166 
167 	sp->event_buffer = buffer;
168 
169 	return 0;
170 }
171 
172 void ibmasm_event_buffer_exit(struct service_processor *sp)
173 {
174 	kfree(sp->event_buffer);
175 }
176