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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * helpers for managing a buffer for many packets4 *5 * Copyright (c) Clemens Ladisch <clemens@ladisch.de>6 */7 8#include <linux/firewire.h>9#include <linux/export.h>10#include <linux/slab.h>11#include "packets-buffer.h"12 13/**14 * iso_packets_buffer_init - allocates the memory for packets15 * @b: the buffer structure to initialize16 * @unit: the device at the other end of the stream17 * @count: the number of packets18 * @packet_size: the (maximum) size of a packet, in bytes19 * @direction: %DMA_TO_DEVICE or %DMA_FROM_DEVICE20 */21int iso_packets_buffer_init(struct iso_packets_buffer *b, struct fw_unit *unit,22 unsigned int count, unsigned int packet_size,23 enum dma_data_direction direction)24{25 unsigned int packets_per_page, pages;26 unsigned int i, page_index, offset_in_page;27 void *p;28 int err;29 30 b->packets = kmalloc_array(count, sizeof(*b->packets), GFP_KERNEL);31 if (!b->packets) {32 err = -ENOMEM;33 goto error;34 }35 36 packet_size = L1_CACHE_ALIGN(packet_size);37 packets_per_page = PAGE_SIZE / packet_size;38 if (WARN_ON(!packets_per_page)) {39 err = -EINVAL;40 goto err_packets;41 }42 pages = DIV_ROUND_UP(count, packets_per_page);43 44 err = fw_iso_buffer_init(&b->iso_buffer, fw_parent_device(unit)->card,45 pages, direction);46 if (err < 0)47 goto err_packets;48 49 for (i = 0; i < count; ++i) {50 page_index = i / packets_per_page;51 p = page_address(b->iso_buffer.pages[page_index]);52 offset_in_page = (i % packets_per_page) * packet_size;53 b->packets[i].buffer = p + offset_in_page;54 b->packets[i].offset = page_index * PAGE_SIZE + offset_in_page;55 }56 57 return 0;58 59err_packets:60 kfree(b->packets);61error:62 return err;63}64EXPORT_SYMBOL(iso_packets_buffer_init);65 66/**67 * iso_packets_buffer_destroy - frees packet buffer resources68 * @b: the buffer structure to free69 * @unit: the device at the other end of the stream70 */71void iso_packets_buffer_destroy(struct iso_packets_buffer *b,72 struct fw_unit *unit)73{74 fw_iso_buffer_destroy(&b->iso_buffer, fw_parent_device(unit)->card);75 kfree(b->packets);76}77EXPORT_SYMBOL(iso_packets_buffer_destroy);78