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Clemens Ladisch31ef9132011-03-15 07:53:21 +01001/*
2 * miscellaneous helper functions
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/delay.h>
9#include <linux/device.h>
10#include <linux/firewire.h>
11#include <linux/module.h>
12#include "lib.h"
13
14#define ERROR_RETRY_DELAY_MS 5
15
16/**
Clemens Ladisch31ef9132011-03-15 07:53:21 +010017 * snd_fw_transaction - send a request and wait for its completion
18 * @unit: the driver's unit on the target device
19 * @tcode: the transaction code
20 * @offset: the address in the target's address space
21 * @buffer: input/output data
22 * @length: length of @buffer
23 *
24 * Submits an asynchronous request to the target device, and waits for the
25 * response. The node ID and the current generation are derived from @unit.
26 * On a bus reset or an error, the transaction is retried a few times.
27 * Returns zero on success, or a negative error code.
28 */
29int snd_fw_transaction(struct fw_unit *unit, int tcode,
30 u64 offset, void *buffer, size_t length)
31{
32 struct fw_device *device = fw_parent_device(unit);
33 int generation, rcode, tries = 0;
34
35 for (;;) {
36 generation = device->generation;
37 smp_rmb(); /* node_id vs. generation */
38 rcode = fw_run_transaction(device->card, tcode,
39 device->node_id, generation,
40 device->max_speed, offset,
41 buffer, length);
42
43 if (rcode == RCODE_COMPLETE)
44 return 0;
45
46 if (rcode_is_permanent_error(rcode) || ++tries >= 3) {
47 dev_err(&unit->device, "transaction failed: %s\n",
Clemens Ladisch7bdbff62012-04-11 17:38:10 +020048 fw_rcode_string(rcode));
Clemens Ladisch31ef9132011-03-15 07:53:21 +010049 return -EIO;
50 }
51
52 msleep(ERROR_RETRY_DELAY_MS);
53 }
54}
55EXPORT_SYMBOL(snd_fw_transaction);
56
57MODULE_DESCRIPTION("FireWire audio helper functions");
58MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>");
59MODULE_LICENSE("GPL v2");