1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * miscellaneous helper functions |
4 | * |
5 | * Copyright (c) Clemens Ladisch <clemens@ladisch.de> |
6 | */ |
7 | |
8 | #include <linux/delay.h> |
9 | #include <linux/device.h> |
10 | #include <linux/firewire.h> |
11 | #include <linux/module.h> |
12 | #include <linux/slab.h> |
13 | #include "lib.h" |
14 | |
15 | #define ERROR_RETRY_DELAY_MS 20 |
16 | |
17 | /** |
18 | * snd_fw_transaction - send a request and wait for its completion |
19 | * @unit: the driver's unit on the target device |
20 | * @tcode: the transaction code |
21 | * @offset: the address in the target's address space |
22 | * @buffer: input/output data |
23 | * @length: length of @buffer |
24 | * @flags: use %FW_FIXED_GENERATION and add the generation value to attempt the |
25 | * request only in that generation; use %FW_QUIET to suppress error |
26 | * messages |
27 | * |
28 | * Submits an asynchronous request to the target device, and waits for the |
29 | * response. The node ID and the current generation are derived from @unit. |
30 | * On a bus reset or an error, the transaction is retried a few times. |
31 | * Returns zero on success, or a negative error code. |
32 | */ |
33 | int snd_fw_transaction(struct fw_unit *unit, int tcode, |
34 | u64 offset, void *buffer, size_t length, |
35 | unsigned int flags) |
36 | { |
37 | struct fw_device *device = fw_parent_device(unit); |
38 | int generation, rcode, tries = 0; |
39 | |
40 | generation = flags & FW_GENERATION_MASK; |
41 | for (;;) { |
42 | if (!(flags & FW_FIXED_GENERATION)) { |
43 | generation = device->generation; |
44 | smp_rmb(); /* node_id vs. generation */ |
45 | } |
46 | rcode = fw_run_transaction(card: device->card, tcode, |
47 | destination_id: device->node_id, generation, |
48 | speed: device->max_speed, offset, |
49 | payload: buffer, length); |
50 | |
51 | if (rcode == RCODE_COMPLETE) |
52 | return 0; |
53 | |
54 | if (rcode == RCODE_GENERATION && (flags & FW_FIXED_GENERATION)) |
55 | return -EAGAIN; |
56 | |
57 | if (rcode_is_permanent_error(rcode) || ++tries >= 3) { |
58 | if (!(flags & FW_QUIET)) |
59 | dev_err(&unit->device, |
60 | "transaction failed: %s\n" , |
61 | fw_rcode_string(rcode)); |
62 | return -EIO; |
63 | } |
64 | |
65 | msleep(ERROR_RETRY_DELAY_MS); |
66 | } |
67 | } |
68 | EXPORT_SYMBOL(snd_fw_transaction); |
69 | |
70 | MODULE_DESCRIPTION("FireWire audio helper functions" ); |
71 | MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>" ); |
72 | MODULE_LICENSE("GPL" ); |
73 | |