77 lines
2.0 KiB
C
77 lines
2.0 KiB
C
/*
|
|
* helpers for managing a buffer for many packets
|
|
*
|
|
* Copyright (c) Clemens Ladisch <clemens@ladisch.de>
|
|
* Licensed under the terms of the GNU General Public License, version 2.
|
|
*/
|
|
|
|
#include <linux/firewire.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(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);
|
|
|
|
/**
|
|
* 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);
|