75 lines
2.0 KiB
C
75 lines
2.0 KiB
C
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/*
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* helpers for managing a buffer for many packets
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*
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* Copyright (c) Clemens Ladisch <clemens@ladisch.de>
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* Licensed under the terms of the GNU General Public License, version 2.
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*/
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#include <linux/firewire.h>
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#include <linux/slab.h>
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#include "packets-buffer.h"
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/**
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* iso_packets_buffer_init - allocates the memory for packets
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* @b: the buffer structure to initialize
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* @unit: the device at the other end of the stream
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* @count: the number of packets
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* @packet_size: the (maximum) size of a packet, in bytes
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* @direction: %DMA_TO_DEVICE or %DMA_FROM_DEVICE
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*/
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int iso_packets_buffer_init(struct iso_packets_buffer *b, struct fw_unit *unit,
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unsigned int count, unsigned int packet_size,
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enum dma_data_direction direction)
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{
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unsigned int packets_per_page, pages;
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unsigned int i, page_index, offset_in_page;
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void *p;
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int err;
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b->packets = kmalloc(count * sizeof(*b->packets), GFP_KERNEL);
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if (!b->packets) {
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err = -ENOMEM;
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goto error;
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}
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packet_size = L1_CACHE_ALIGN(packet_size);
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packets_per_page = PAGE_SIZE / packet_size;
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if (WARN_ON(!packets_per_page)) {
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err = -EINVAL;
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goto error;
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}
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pages = DIV_ROUND_UP(count, packets_per_page);
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err = fw_iso_buffer_init(&b->iso_buffer, fw_parent_device(unit)->card,
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pages, direction);
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if (err < 0)
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goto err_packets;
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for (i = 0; i < count; ++i) {
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page_index = i / packets_per_page;
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p = page_address(b->iso_buffer.pages[page_index]);
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offset_in_page = (i % packets_per_page) * packet_size;
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b->packets[i].buffer = p + offset_in_page;
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b->packets[i].offset = page_index * PAGE_SIZE + offset_in_page;
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}
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return 0;
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err_packets:
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kfree(b->packets);
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error:
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return err;
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}
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/**
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* iso_packets_buffer_destroy - frees packet buffer resources
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* @b: the buffer structure to free
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* @unit: the device at the other end of the stream
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*/
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void iso_packets_buffer_destroy(struct iso_packets_buffer *b,
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struct fw_unit *unit)
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{
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fw_iso_buffer_destroy(&b->iso_buffer, fw_parent_device(unit)->card);
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kfree(b->packets);
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}
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