GNU Linux-libre 4.4.284-gnu1
[releases.git] / drivers / misc / ibmasm / event.c
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
40 static 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  */
57 void 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
80 static 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  */
91 int 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
124 void ibmasm_cancel_next_event(struct event_reader *reader)
125 {
126         reader->cancelled = 1;
127         wake_up_interruptible(&reader->wait);
128 }
129
130 void 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
141 void 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
150 int 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
174 void ibmasm_event_buffer_exit(struct service_processor *sp)
175 {
176         kfree(sp->event_buffer);
177 }