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 }