1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * helpers for managing a buffer for many packets
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
6*4882a593Smuzhiyun */
7*4882a593Smuzhiyun
8*4882a593Smuzhiyun #include <linux/firewire.h>
9*4882a593Smuzhiyun #include <linux/export.h>
10*4882a593Smuzhiyun #include <linux/slab.h>
11*4882a593Smuzhiyun #include "packets-buffer.h"
12*4882a593Smuzhiyun
13*4882a593Smuzhiyun /**
14*4882a593Smuzhiyun * iso_packets_buffer_init - allocates the memory for packets
15*4882a593Smuzhiyun * @b: the buffer structure to initialize
16*4882a593Smuzhiyun * @unit: the device at the other end of the stream
17*4882a593Smuzhiyun * @count: the number of packets
18*4882a593Smuzhiyun * @packet_size: the (maximum) size of a packet, in bytes
19*4882a593Smuzhiyun * @direction: %DMA_TO_DEVICE or %DMA_FROM_DEVICE
20*4882a593Smuzhiyun */
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*4882a593Smuzhiyun int iso_packets_buffer_init(struct iso_packets_buffer *b, struct fw_unit *unit,
22*4882a593Smuzhiyun unsigned int count, unsigned int packet_size,
23*4882a593Smuzhiyun enum dma_data_direction direction)
24*4882a593Smuzhiyun {
25*4882a593Smuzhiyun unsigned int packets_per_page, pages;
26*4882a593Smuzhiyun unsigned int i, page_index, offset_in_page;
27*4882a593Smuzhiyun void *p;
28*4882a593Smuzhiyun int err;
29*4882a593Smuzhiyun
30*4882a593Smuzhiyun b->packets = kmalloc_array(count, sizeof(*b->packets), GFP_KERNEL);
31*4882a593Smuzhiyun if (!b->packets) {
32*4882a593Smuzhiyun err = -ENOMEM;
33*4882a593Smuzhiyun goto error;
34*4882a593Smuzhiyun }
35*4882a593Smuzhiyun
36*4882a593Smuzhiyun packet_size = L1_CACHE_ALIGN(packet_size);
37*4882a593Smuzhiyun packets_per_page = PAGE_SIZE / packet_size;
38*4882a593Smuzhiyun if (WARN_ON(!packets_per_page)) {
39*4882a593Smuzhiyun err = -EINVAL;
40*4882a593Smuzhiyun goto err_packets;
41*4882a593Smuzhiyun }
42*4882a593Smuzhiyun pages = DIV_ROUND_UP(count, packets_per_page);
43*4882a593Smuzhiyun
44*4882a593Smuzhiyun err = fw_iso_buffer_init(&b->iso_buffer, fw_parent_device(unit)->card,
45*4882a593Smuzhiyun pages, direction);
46*4882a593Smuzhiyun if (err < 0)
47*4882a593Smuzhiyun goto err_packets;
48*4882a593Smuzhiyun
49*4882a593Smuzhiyun for (i = 0; i < count; ++i) {
50*4882a593Smuzhiyun page_index = i / packets_per_page;
51*4882a593Smuzhiyun p = page_address(b->iso_buffer.pages[page_index]);
52*4882a593Smuzhiyun offset_in_page = (i % packets_per_page) * packet_size;
53*4882a593Smuzhiyun b->packets[i].buffer = p + offset_in_page;
54*4882a593Smuzhiyun b->packets[i].offset = page_index * PAGE_SIZE + offset_in_page;
55*4882a593Smuzhiyun }
56*4882a593Smuzhiyun
57*4882a593Smuzhiyun return 0;
58*4882a593Smuzhiyun
59*4882a593Smuzhiyun err_packets:
60*4882a593Smuzhiyun kfree(b->packets);
61*4882a593Smuzhiyun error:
62*4882a593Smuzhiyun return err;
63*4882a593Smuzhiyun }
64*4882a593Smuzhiyun EXPORT_SYMBOL(iso_packets_buffer_init);
65*4882a593Smuzhiyun
66*4882a593Smuzhiyun /**
67*4882a593Smuzhiyun * iso_packets_buffer_destroy - frees packet buffer resources
68*4882a593Smuzhiyun * @b: the buffer structure to free
69*4882a593Smuzhiyun * @unit: the device at the other end of the stream
70*4882a593Smuzhiyun */
iso_packets_buffer_destroy(struct iso_packets_buffer * b,struct fw_unit * unit)71*4882a593Smuzhiyun void iso_packets_buffer_destroy(struct iso_packets_buffer *b,
72*4882a593Smuzhiyun struct fw_unit *unit)
73*4882a593Smuzhiyun {
74*4882a593Smuzhiyun fw_iso_buffer_destroy(&b->iso_buffer, fw_parent_device(unit)->card);
75*4882a593Smuzhiyun kfree(b->packets);
76*4882a593Smuzhiyun }
77*4882a593Smuzhiyun EXPORT_SYMBOL(iso_packets_buffer_destroy);
78