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