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31ef9134 CL |
1 | /* |
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 | ||
31ef9134 CL |
16 | /** |
17 | * 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 | */ | |
29 | int 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", | |
7bdbff67 | 48 | fw_rcode_string(rcode)); |
31ef9134 CL |
49 | return -EIO; |
50 | } | |
51 | ||
52 | msleep(ERROR_RETRY_DELAY_MS); | |
53 | } | |
54 | } | |
55 | EXPORT_SYMBOL(snd_fw_transaction); | |
56 | ||
57 | MODULE_DESCRIPTION("FireWire audio helper functions"); | |
58 | MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>"); | |
59 | MODULE_LICENSE("GPL v2"); |