event.c

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/*
 * IBM ASM Service Processor Device Driver
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright (C) IBM Corporation, 2004
 *
 * Author: Max Asböck <[email protected]>
 *
 */

#include <linux/sched.h>
#include <linux/slab.h>
#include "ibmasm.h"
#include "lowlevel.h"

/*
 * ASM service processor event handling routines.
 *
 * Events are signalled to the device drivers through interrupts.
 * They have the format of dot commands, with the type field set to
 * sp_event.
 * The driver does not interpret the events, it simply stores them in a
 * circular buffer.
 */

static void wake_up_event_readers(struct service_processor *sp)
{
    struct event_reader *reader;

    list_for_each_entry(reader, &sp->event_buffer->readers, node)
                wake_up_interruptible(&reader->wait);
}

void ibmasm_receive_event(struct service_processor *sp, void *data, unsigned int data_size)
{
    struct event_buffer *buffer = sp->event_buffer;
    struct ibmasm_event *event;
    unsigned long flags;

    data_size = min(data_size, IBMASM_EVENT_MAX_SIZE);

    spin_lock_irqsave(&sp->lock, flags);
    /* copy the event into the next slot in the circular buffer */
    event = &buffer->events[buffer->next_index];
    memcpy_fromio(event->data, data, data_size);
    event->data_size = data_size;
    event->serial_number = buffer->next_serial_number;

    /* advance indices in the buffer */
    buffer->next_index = (buffer->next_index + 1) % IBMASM_NUM_EVENTS;
    buffer->next_serial_number++;
    spin_unlock_irqrestore(&sp->lock, flags);

    wake_up_event_readers(sp);
}

static inline int event_available(struct event_buffer *b, struct event_reader *r)
{
    return (r->next_serial_number < b->next_serial_number);
}

int ibmasm_get_next_event(struct service_processor *sp, struct event_reader *reader)
{
    struct event_buffer *buffer = sp->event_buffer;
    struct ibmasm_event *event;
    unsigned int index;
    unsigned long flags;

    reader->cancelled = 0;

    if (wait_event_interruptible(reader->wait,
            event_available(buffer, reader) || reader->cancelled))
        return -ERESTARTSYS;

    if (!event_available(buffer, reader))
        return 0;

    spin_lock_irqsave(&sp->lock, flags);

    index = buffer->next_index;
    event = &buffer->events[index];
    while (event->serial_number < reader->next_serial_number) {
        index = (index + 1) % IBMASM_NUM_EVENTS;
        event = &buffer->events[index];
    }
    memcpy(reader->data, event->data, event->data_size);
    reader->data_size = event->data_size;
    reader->next_serial_number = event->serial_number + 1;

    spin_unlock_irqrestore(&sp->lock, flags);

    return event->data_size;
}

void ibmasm_cancel_next_event(struct event_reader *reader)
{
        reader->cancelled = 1;
        wake_up_interruptible(&reader->wait);
}

void ibmasm_event_reader_register(struct service_processor *sp, struct event_reader *reader)
{
    unsigned long flags;

    reader->next_serial_number = sp->event_buffer->next_serial_number;
    init_waitqueue_head(&reader->wait);
    spin_lock_irqsave(&sp->lock, flags);
    list_add(&reader->node, &sp->event_buffer->readers);
    spin_unlock_irqrestore(&sp->lock, flags);
}

void ibmasm_event_reader_unregister(struct service_processor *sp, struct event_reader *reader)
{
    unsigned long flags;

    spin_lock_irqsave(&sp->lock, flags);
    list_del(&reader->node);
    spin_unlock_irqrestore(&sp->lock, flags);
}

int ibmasm_event_buffer_init(struct service_processor *sp)
{
    struct event_buffer *buffer;
    struct ibmasm_event *event;
    int i;

    buffer = kmalloc(sizeof(struct event_buffer), GFP_KERNEL);
    if (!buffer)
        return 1;

    buffer->next_index = 0;
    buffer->next_serial_number = 1;

    event = buffer->events;
    for (i=0; i<IBMASM_NUM_EVENTS; i++, event++)
        event->serial_number = 0;

    INIT_LIST_HEAD(&buffer->readers);

    sp->event_buffer = buffer;

    return 0;
}

void ibmasm_event_buffer_exit(struct service_processor *sp)
{
    kfree(sp->event_buffer);
}