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
  27 /*
  28  * ASM service processor event handling routines.
  29  *
  30  * Events are signalled to the device drivers through interrupts.
  31  * They have the format of dot commands, with the type field set to
  32  * sp_event.
  33  * The driver does not interpret the events, it simply stores them in a
  34  * circular buffer.
  35  */
  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(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         if (wait_event_interruptible(reader->wait, event_available(buffer, reader)))
  97                 return -ERESTARTSYS;
  98
  99         if (!event_available(buffer, reader))
 100                 return 0;
 101
 102         spin_lock_irqsave(&sp->lock, flags);
 103
 104         index = buffer->next_index;
 105         event = &buffer->events[index];
 106         while (event->serial_number < reader->next_serial_number) {
 107                 index = (index + 1) % IBMASM_NUM_EVENTS;
 108                 event = &buffer->events[index];
 109         }
 110         memcpy(reader->data, event->data, event->data_size);
 111         reader->data_size = event->data_size;
 112         reader->next_serial_number = event->serial_number + 1;
 113
 114         spin_unlock_irqrestore(&sp->lock, flags);
 115
 116         return event->data_size;
 117 }
 118
 119 void ibmasm_event_reader_register(struct service_processor *sp, struct event_reader *reader)
 120 {
 121         unsigned long flags;
 122
 123         reader->next_serial_number = sp->event_buffer->next_serial_number;
 124         init_waitqueue_head(&reader->wait);
 125         spin_lock_irqsave(&sp->lock, flags);
 126         list_add(&reader->node, &sp->event_buffer->readers);
 127         spin_unlock_irqrestore(&sp->lock, flags);
 128 }
 129
 130 void ibmasm_event_reader_unregister(struct service_processor *sp, struct event_reader *reader)
 131 {
 132         unsigned long flags;
 133
 134         wake_up_interruptible(&reader->wait);
 135
 136         spin_lock_irqsave(&sp->lock, flags);
 137         list_del(&reader->node);
 138         spin_unlock_irqrestore(&sp->lock, flags);
 139 }
 140
 141 int ibmasm_event_buffer_init(struct service_processor *sp)
 142 {
 143         struct event_buffer *buffer;
 144         struct ibmasm_event *event;
 145         int i;
 146
 147         buffer = kmalloc(sizeof(struct event_buffer), GFP_KERNEL);
 148         if (!buffer)
 149                 return 1;
 150
 151         buffer->next_index = 0;
 152         buffer->next_serial_number = 1;
 153
 154         event = buffer->events;
 155         for (i=0; i<IBMASM_NUM_EVENTS; i++, event++)
 156                 event->serial_number = 0;
 157
 158         INIT_LIST_HEAD(&buffer->readers);
 159
 160         sp->event_buffer = buffer;
 161
 162         return 0;
 163 }
 164
 165 void ibmasm_event_buffer_exit(struct service_processor *sp)
 166 {
 167         wake_up_event_readers(sp);
 168         kfree(sp->event_buffer);
 169 }