/* * 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_array(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);