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 "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 }