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/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 */ 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(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 error; 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 */ 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