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 */
 33int 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}
 68EXPORT_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 */
 84void 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}
100EXPORT_SYMBOL(snd_fw_schedule_registration);
101
102MODULE_DESCRIPTION("FireWire audio helper functions");
103MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>");
104MODULE_LICENSE("GPL v2");