sound/firewire/packets-buffer.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * helpers for managing a buffer for many packets
0004  *
0005  * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
0006  */
0007
0008 #include <linux/firewire.h>
0009 #include <linux/export.h>
0010 #include <linux/slab.h>
0011 #include "packets-buffer.h"
0012
0013 /**
0014  * iso_packets_buffer_init - allocates the memory for packets
0015  * @b: the buffer structure to initialize
0016  * @unit: the device at the other end of the stream
0017  * @count: the number of packets
0018  * @packet_size: the (maximum) size of a packet, in bytes
0019  * @direction: %DMA_TO_DEVICE or %DMA_FROM_DEVICE
0020  */
0021 int iso_packets_buffer_init(struct iso_packets_buffer *b, struct fw_unit *unit,
0022                 unsigned int count, unsigned int packet_size,
0023                 enum dma_data_direction direction)
0024 {
0025     unsigned int packets_per_page, pages;
0026     unsigned int i, page_index, offset_in_page;
0027     void *p;
0028     int err;
0029
0030     b->packets = kmalloc_array(count, sizeof(*b->packets), GFP_KERNEL);
0031     if (!b->packets) {
0032         err = -ENOMEM;
0033         goto error;
0034     }
0035
0036     packet_size = L1_CACHE_ALIGN(packet_size);
0037     packets_per_page = PAGE_SIZE / packet_size;
0038     if (WARN_ON(!packets_per_page)) {
0039         err = -EINVAL;
0040         goto err_packets;
0041     }
0042     pages = DIV_ROUND_UP(count, packets_per_page);
0043
0044     err = fw_iso_buffer_init(&b->iso_buffer, fw_parent_device(unit)->card,
0045                  pages, direction);
0046     if (err < 0)
0047         goto err_packets;
0048
0049     for (i = 0; i < count; ++i) {
0050         page_index = i / packets_per_page;
0051         p = page_address(b->iso_buffer.pages[page_index]);
0052         offset_in_page = (i % packets_per_page) * packet_size;
0053         b->packets[i].buffer = p + offset_in_page;
0054         b->packets[i].offset = page_index * PAGE_SIZE + offset_in_page;
0055     }
0056
0057     return 0;
0058
0059 err_packets:
0060     kfree(b->packets);
0061 error:
0062     return err;
0063 }
0064 EXPORT_SYMBOL(iso_packets_buffer_init);
0065
0066 /**
0067  * iso_packets_buffer_destroy - frees packet buffer resources
0068  * @b: the buffer structure to free
0069  * @unit: the device at the other end of the stream
0070  */
0071 void iso_packets_buffer_destroy(struct iso_packets_buffer *b,
0072                 struct fw_unit *unit)
0073 {
0074     fw_iso_buffer_destroy(&b->iso_buffer, fw_parent_device(unit)->card);
0075     kfree(b->packets);
0076 }
0077 EXPORT_SYMBOL(iso_packets_buffer_destroy);