packets-buffer.c

Go to the documentation of this file.

/*
 * helpers for managing a buffer for many packets
 *
 * Copyright (c) Clemens Ladisch <[email protected]>
 * Licensed under the terms of the GNU General Public License, version 2.
 */

#include <linux/firewire.h>
#include <linux/export.h>
#include <linux/slab.h>
#include "packets-buffer.h"

int iso_packets_buffer_init(struct iso_packets_buffer *b, struct fw_unit *unit,
                unsigned int count, unsigned int packet_size,
                enum dma_data_direction direction)
{
    unsigned int packets_per_page, pages;
    unsigned int i, page_index, offset_in_page;
    void *p;
    int err;

    b->packets = kmalloc(count * sizeof(*b->packets), GFP_KERNEL);
    if (!b->packets) {
        err = -ENOMEM;
        goto error;
    }

    packet_size = L1_CACHE_ALIGN(packet_size);
    packets_per_page = PAGE_SIZE / packet_size;
    if (WARN_ON(!packets_per_page)) {
        err = -EINVAL;
        goto error;
    }
    pages = DIV_ROUND_UP(count, packets_per_page);

    err = fw_iso_buffer_init(&b->iso_buffer, fw_parent_device(unit)->card,
                 pages, direction);
    if (err < 0)
        goto err_packets;

    for (i = 0; i < count; ++i) {
        page_index = i / packets_per_page;
        p = page_address(b->iso_buffer.pages[page_index]);
        offset_in_page = (i % packets_per_page) * packet_size;
        b->packets[i].buffer = p + offset_in_page;
        b->packets[i].offset = page_index * PAGE_SIZE + offset_in_page;
    }

    return 0;

err_packets:
    kfree(b->packets);
error:
    return err;
}
EXPORT_SYMBOL(iso_packets_buffer_init);

void iso_packets_buffer_destroy(struct iso_packets_buffer *b,
                struct fw_unit *unit)
{
    fw_iso_buffer_destroy(&b->iso_buffer, fw_parent_device(unit)->card);
    kfree(b->packets);
}
EXPORT_SYMBOL(iso_packets_buffer_destroy);