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 Asböck <amax@us.ibm.com>
22 *
23 */
24
25#include <linux/sched.h>
26#include <linux/slab.h>
27#include "ibmasm.h"
28#include "lowlevel.h"
29
30/*
31 * ASM service processor event handling routines.
32 *
33 * Events are signalled to the device drivers through interrupts.
34 * They have the format of dot commands, with the type field set to
35 * sp_event.
36 * The driver does not interpret the events, it simply stores them in a
37 * circular buffer.
38 */
39
40static void wake_up_event_readers(struct service_processor *sp)
41{
42	struct event_reader *reader;
43
44	list_for_each_entry(reader, &sp->event_buffer->readers, node)
45                wake_up_interruptible(&reader->wait);
46}
47
48/**
49 * receive_event
50 * Called by the interrupt handler when a dot command of type sp_event is
51 * received.
52 * Store the event in the circular event buffer, wake up any sleeping
53 * event readers.
54 * There is no reader marker in the buffer, therefore readers are
55 * responsible for keeping up with the writer, or they will lose events.
56 */
57void ibmasm_receive_event(struct service_processor *sp, void *data, unsigned int data_size)
58{
59	struct event_buffer *buffer = sp->event_buffer;
60	struct ibmasm_event *event;
61	unsigned long flags;
62
63	data_size = min(data_size, IBMASM_EVENT_MAX_SIZE);
64
65	spin_lock_irqsave(&sp->lock, flags);
66	/* copy the event into the next slot in the circular buffer */
67	event = &buffer->events[buffer->next_index];
68	memcpy_fromio(event->data, data, data_size);
69	event->data_size = data_size;
70	event->serial_number = buffer->next_serial_number;
71
72	/* advance indices in the buffer */
73	buffer->next_index = (buffer->next_index + 1) % IBMASM_NUM_EVENTS;
74	buffer->next_serial_number++;
75	spin_unlock_irqrestore(&sp->lock, flags);
76
77	wake_up_event_readers(sp);
78}
79
80static inline int event_available(struct event_buffer *b, struct event_reader *r)
81{
82	return (r->next_serial_number < b->next_serial_number);
83}
84
85/**
86 * get_next_event
87 * Called by event readers (initiated from user space through the file
88 * system).
89 * Sleeps until a new event is available.
90 */
91int ibmasm_get_next_event(struct service_processor *sp, struct event_reader *reader)
92{
93	struct event_buffer *buffer = sp->event_buffer;
94	struct ibmasm_event *event;
95	unsigned int index;
96	unsigned long flags;
97
98	reader->cancelled = 0;
99
100	if (wait_event_interruptible(reader->wait,
101			event_available(buffer, reader) || reader->cancelled))
102		return -ERESTARTSYS;
103
104	if (!event_available(buffer, reader))
105		return 0;
106
107	spin_lock_irqsave(&sp->lock, flags);
108
109	index = buffer->next_index;
110	event = &buffer->events[index];
111	while (event->serial_number < reader->next_serial_number) {
112		index = (index + 1) % IBMASM_NUM_EVENTS;
113		event = &buffer->events[index];
114	}
115	memcpy(reader->data, event->data, event->data_size);
116	reader->data_size = event->data_size;
117	reader->next_serial_number = event->serial_number + 1;
118
119	spin_unlock_irqrestore(&sp->lock, flags);
120
121	return event->data_size;
122}
123
124void ibmasm_cancel_next_event(struct event_reader *reader)
125{
126        reader->cancelled = 1;
127        wake_up_interruptible(&reader->wait);
128}
129
130void ibmasm_event_reader_register(struct service_processor *sp, struct event_reader *reader)
131{
132	unsigned long flags;
133
134	reader->next_serial_number = sp->event_buffer->next_serial_number;
135	init_waitqueue_head(&reader->wait);
136	spin_lock_irqsave(&sp->lock, flags);
137	list_add(&reader->node, &sp->event_buffer->readers);
138	spin_unlock_irqrestore(&sp->lock, flags);
139}
140
141void ibmasm_event_reader_unregister(struct service_processor *sp, struct event_reader *reader)
142{
143	unsigned long flags;
144
145	spin_lock_irqsave(&sp->lock, flags);
146	list_del(&reader->node);
147	spin_unlock_irqrestore(&sp->lock, flags);
148}
149
150int ibmasm_event_buffer_init(struct service_processor *sp)
151{
152	struct event_buffer *buffer;
153	struct ibmasm_event *event;
154	int i;
155
156	buffer = kmalloc(sizeof(struct event_buffer), GFP_KERNEL);
157	if (!buffer)
158		return 1;
159
160	buffer->next_index = 0;
161	buffer->next_serial_number = 1;
162
163	event = buffer->events;
164	for (i=0; i<IBMASM_NUM_EVENTS; i++, event++)
165		event->serial_number = 0;
166
167	INIT_LIST_HEAD(&buffer->readers);
168
169	sp->event_buffer = buffer;
170
171	return 0;
172}
173
174void ibmasm_event_buffer_exit(struct service_processor *sp)
175{
176	kfree(sp->event_buffer);
177}
178