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