ALSA: isight: add AudioEnable register write
[linux-2.6.git] / sound / firewire / packets-buffer.c
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 EXPORT_SYMBOL(iso_packets_buffer_init);
64
65 /**
66  * iso_packets_buffer_destroy - frees packet buffer resources
67  * @b: the buffer structure to free
68  * @unit: the device at the other end of the stream
69  */
70 void iso_packets_buffer_destroy(struct iso_packets_buffer *b,
71                                 struct fw_unit *unit)
72 {
73         fw_iso_buffer_destroy(&b->iso_buffer, fw_parent_device(unit)->card);
74         kfree(b->packets);
75 }
76 EXPORT_SYMBOL(iso_packets_buffer_destroy);