| /* |
| * 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 err_packets; |
| } |
| 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); |