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 */
snd_fw_transaction(struct fw_unit * unit,int tcode,u64 offset,void * buffer,size_t length,unsigned int flags)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(device->card, tcode,
47 device->node_id, generation,
48 device->max_speed, offset,
49 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 #define PROBE_DELAY_MS (2 * MSEC_PER_SEC)
71
72 /**
73 * snd_fw_schedule_registration - schedule work for sound card registration
74 * @unit: an instance for unit on IEEE 1394 bus
75 * @dwork: delayed work with callback function
76 *
77 * This function is not designed for general purposes. When new unit is
78 * connected to IEEE 1394 bus, the bus is under bus-reset state because of
79 * topological change. In this state, units tend to fail both of asynchronous
80 * and isochronous communication. To avoid this problem, this function is used
81 * to postpone sound card registration after the state. The callers must
82 * set up instance of delayed work in advance.
83 */
snd_fw_schedule_registration(struct fw_unit * unit,struct delayed_work * dwork)84 void snd_fw_schedule_registration(struct fw_unit *unit,
85 struct delayed_work *dwork)
86 {
87 u64 now, delay;
88
89 now = get_jiffies_64();
90 delay = fw_parent_device(unit)->card->reset_jiffies
91 + msecs_to_jiffies(PROBE_DELAY_MS);
92
93 if (time_after64(delay, now))
94 delay -= now;
95 else
96 delay = 0;
97
98 mod_delayed_work(system_wq, dwork, delay);
99 }
100 EXPORT_SYMBOL(snd_fw_schedule_registration);
101
102 MODULE_DESCRIPTION("FireWire audio helper functions");
103 MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>");
104 MODULE_LICENSE("GPL v2");
105
