/* * 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/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(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);