1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * helpers for managing a buffer for many packets
4 *
5 * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
6 */
7
8 #include <linux/firewire.h>
9 #include <linux/export.h>
10 #include <linux/slab.h>
11 #include "packets-buffer.h"
12
13 /**
14 * iso_packets_buffer_init - allocates the memory for packets
15 * @b: the buffer structure to initialize
16 * @unit: the device at the other end of the stream
17 * @count: the number of packets
18 * @packet_size: the (maximum) size of a packet, in bytes
19 * @direction: %DMA_TO_DEVICE or %DMA_FROM_DEVICE
20 */
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)21 int iso_packets_buffer_init(struct iso_packets_buffer *b, struct fw_unit *unit,
22 unsigned int count, unsigned int packet_size,
23 enum dma_data_direction direction)
24 {
25 unsigned int packets_per_page, pages;
26 unsigned int i, page_index, offset_in_page;
27 void *p;
28 int err;
29
30 b->packets = kmalloc_array(count, sizeof(*b->packets), GFP_KERNEL);
31 if (!b->packets) {
32 err = -ENOMEM;
33 goto error;
34 }
35
36 packet_size = L1_CACHE_ALIGN(packet_size);
37 packets_per_page = PAGE_SIZE / packet_size;
38 if (WARN_ON(!packets_per_page)) {
39 err = -EINVAL;
40 goto err_packets;
41 }
42 pages = DIV_ROUND_UP(count, packets_per_page);
43
44 err = fw_iso_buffer_init(&b->iso_buffer, fw_parent_device(unit)->card,
45 pages, direction);
46 if (err < 0)
47 goto err_packets;
48
49 for (i = 0; i < count; ++i) {
50 page_index = i / packets_per_page;
51 p = page_address(b->iso_buffer.pages[page_index]);
52 offset_in_page = (i % packets_per_page) * packet_size;
53 b->packets[i].buffer = p + offset_in_page;
54 b->packets[i].offset = page_index * PAGE_SIZE + offset_in_page;
55 }
56
57 return 0;
58
59 err_packets:
60 kfree(b->packets);
61 error:
62 return err;
63 }
64 EXPORT_SYMBOL(iso_packets_buffer_init);
65
66 /**
67 * iso_packets_buffer_destroy - frees packet buffer resources
68 * @b: the buffer structure to free
69 * @unit: the device at the other end of the stream
70 */
iso_packets_buffer_destroy(struct iso_packets_buffer * b,struct fw_unit * unit)71 void iso_packets_buffer_destroy(struct iso_packets_buffer *b,
72 struct fw_unit *unit)
73 {
74 fw_iso_buffer_destroy(&b->iso_buffer, fw_parent_device(unit)->card);
75 kfree(b->packets);
76 }
77 EXPORT_SYMBOL(iso_packets_buffer_destroy);
78