105 lines
3.1 KiB
C
105 lines
3.1 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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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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*/
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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 <linux/slab.h>
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#include "lib.h"
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#define ERROR_RETRY_DELAY_MS 20
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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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* @flags: use %FW_FIXED_GENERATION and add the generation value to attempt the
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* request only in that generation; use %FW_QUIET to suppress error
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* messages
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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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unsigned int flags)
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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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generation = flags & FW_GENERATION_MASK;
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for (;;) {
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if (!(flags & FW_FIXED_GENERATION)) {
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generation = device->generation;
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smp_rmb(); /* node_id vs. generation */
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}
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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 == RCODE_GENERATION && (flags & FW_FIXED_GENERATION))
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return -EAGAIN;
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if (rcode_is_permanent_error(rcode) || ++tries >= 3) {
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if (!(flags & FW_QUIET))
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dev_err(&unit->device,
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"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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#define PROBE_DELAY_MS (2 * MSEC_PER_SEC)
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/**
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* snd_fw_schedule_registration - schedule work for sound card registration
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* @unit: an instance for unit on IEEE 1394 bus
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* @dwork: delayed work with callback function
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*
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* This function is not designed for general purposes. When new unit is
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* connected to IEEE 1394 bus, the bus is under bus-reset state because of
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* topological change. In this state, units tend to fail both of asynchronous
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* and isochronous communication. To avoid this problem, this function is used
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* to postpone sound card registration after the state. The callers must
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* set up instance of delayed work in advance.
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*/
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void snd_fw_schedule_registration(struct fw_unit *unit,
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struct delayed_work *dwork)
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{
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u64 now, delay;
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now = get_jiffies_64();
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delay = fw_parent_device(unit)->card->reset_jiffies
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+ msecs_to_jiffies(PROBE_DELAY_MS);
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if (time_after64(delay, now))
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delay -= now;
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else
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delay = 0;
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mod_delayed_work(system_wq, dwork, delay);
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}
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EXPORT_SYMBOL(snd_fw_schedule_registration);
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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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