| Clemens Ladisch | 31ef913 | 2011-03-15 07:53:21 +0100 | [diff] [blame] | 1 | /* |
| 2 | * helpers for managing a buffer for many packets |
| 3 | * |
| 4 | * Copyright (c) Clemens Ladisch <clemens@ladisch.de> |
| 5 | * Licensed under the terms of the GNU General Public License, version 2. |
| 6 | */ |
| 7 | |
| 8 | #include <linux/firewire.h> |
| 9 | #include <linux/slab.h> |
| 10 | #include "packets-buffer.h" |
| 11 | |
| 12 | /** |
| 13 | * iso_packets_buffer_init - allocates the memory for packets |
| 14 | * @b: the buffer structure to initialize |
| 15 | * @unit: the device at the other end of the stream |
| 16 | * @count: the number of packets |
| 17 | * @packet_size: the (maximum) size of a packet, in bytes |
| 18 | * @direction: %DMA_TO_DEVICE or %DMA_FROM_DEVICE |
| 19 | */ |
| 20 | int iso_packets_buffer_init(struct iso_packets_buffer *b, struct fw_unit *unit, |
| 21 | unsigned int count, unsigned int packet_size, |
| 22 | enum dma_data_direction direction) |
| 23 | { |
| 24 | unsigned int packets_per_page, pages; |
| 25 | unsigned int i, page_index, offset_in_page; |
| 26 | void *p; |
| 27 | int err; |
| 28 | |
| 29 | b->packets = kmalloc(count * sizeof(*b->packets), GFP_KERNEL); |
| 30 | if (!b->packets) { |
| 31 | err = -ENOMEM; |
| 32 | goto error; |
| 33 | } |
| 34 | |
| 35 | packet_size = L1_CACHE_ALIGN(packet_size); |
| 36 | packets_per_page = PAGE_SIZE / packet_size; |
| 37 | if (WARN_ON(!packets_per_page)) { |
| 38 | err = -EINVAL; |
| 39 | goto error; |
| 40 | } |
| 41 | pages = DIV_ROUND_UP(count, packets_per_page); |
| 42 | |
| 43 | err = fw_iso_buffer_init(&b->iso_buffer, fw_parent_device(unit)->card, |
| 44 | pages, direction); |
| 45 | if (err < 0) |
| 46 | goto err_packets; |
| 47 | |
| 48 | for (i = 0; i < count; ++i) { |
| 49 | page_index = i / packets_per_page; |
| 50 | p = page_address(b->iso_buffer.pages[page_index]); |
| 51 | offset_in_page = (i % packets_per_page) * packet_size; |
| 52 | b->packets[i].buffer = p + offset_in_page; |
| 53 | b->packets[i].offset = page_index * PAGE_SIZE + offset_in_page; |
| 54 | } |
| 55 | |
| 56 | return 0; |
| 57 | |
| 58 | err_packets: |
| 59 | kfree(b->packets); |
| 60 | error: |
| 61 | return err; |
| 62 | } |
| 63 | |
| 64 | /** |
| 65 | * iso_packets_buffer_destroy - frees packet buffer resources |
| 66 | * @b: the buffer structure to free |
| 67 | * @unit: the device at the other end of the stream |
| 68 | */ |
| 69 | void iso_packets_buffer_destroy(struct iso_packets_buffer *b, |
| 70 | struct fw_unit *unit) |
| 71 | { |
| 72 | fw_iso_buffer_destroy(&b->iso_buffer, fw_parent_device(unit)->card); |
| 73 | kfree(b->packets); |
| 74 | } |