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