// SPDX-License-Identifier: GPL-2.0-only
/*
 * helpers for managing a buffer for many packets
 *
 * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
 */

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

/**
 * iso_packets_buffer_init - allocates the memory for packets
 * @b: the buffer structure to initialize
 * @unit: the device at the other end of the stream
 * @count: the number of packets
 * @packet_size: the (maximum) size of a packet, in bytes
 * @direction: %DMA_TO_DEVICE or %DMA_FROM_DEVICE
 */
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_objs(*b->packets, count);
        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 err_packets;
        }
        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);

/**
 * iso_packets_buffer_destroy - frees packet buffer resources
 * @b: the buffer structure to free
 * @unit: the device at the other end of the stream
 */
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);