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/*
* miscellaneous helper functions
*
* Copyright (c) Clemens Ladisch <clemens@ladisch.de>
* Licensed under the terms of the GNU General Public License, version 2.
*/
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/firewire.h>
#include <linux/module.h>
#include "lib.h"
#define ERROR_RETRY_DELAY_MS 5
/**
* snd_fw_transaction - send a request and wait for its completion
* @unit: the driver's unit on the target device
* @tcode: the transaction code
* @offset: the address in the target's address space
* @buffer: input/output data
* @length: length of @buffer
*
* Submits an asynchronous request to the target device, and waits for the
* response. The node ID and the current generation are derived from @unit.
* On a bus reset or an error, the transaction is retried a few times.
* Returns zero on success, or a negative error code.
*/
int snd_fw_transaction(struct fw_unit *unit, int tcode,
u64 offset, void *buffer, size_t length)
{
struct fw_device *device = fw_parent_device(unit);
int generation, rcode, tries = 0;
for (;;) {
generation = device->generation;
smp_rmb(); /* node_id vs. generation */
rcode = fw_run_transaction(device->card, tcode,
device->node_id, generation,
device->max_speed, offset,
buffer, length);
if (rcode == RCODE_COMPLETE)
return 0;
if (rcode_is_permanent_error(rcode) || ++tries >= 3) {
dev_err(&unit->device, "transaction failed: %s\n",
fw_rcode_string(rcode));
return -EIO;
}
msleep(ERROR_RETRY_DELAY_MS);
}
}
EXPORT_SYMBOL(snd_fw_transaction);
MODULE_DESCRIPTION("FireWire audio helper functions");
MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>");
MODULE_LICENSE("GPL v2");
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