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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 | |
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", |
48 | fw_rcode_string(rcode)); |
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"); |
60 |
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