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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 <linux/slab.h>
#include "lib.h"
#define ERROR_RETRY_DELAY_MS 20
/**
* 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
* @flags: use %FW_FIXED_GENERATION and add the generation value to attempt the
* request only in that generation; use %FW_QUIET to suppress error
* messages
*
* 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,
unsigned int flags)
{
struct fw_device *device = fw_parent_device(unit);
int generation, rcode, tries = 0;
generation = flags & FW_GENERATION_MASK;
for (;;) {
if (!(flags & FW_FIXED_GENERATION)) {
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 == RCODE_GENERATION && (flags & FW_FIXED_GENERATION))
return -EAGAIN;
if (rcode_is_permanent_error(rcode) || ++tries >= 3) {
if (!(flags & FW_QUIET))
dev_err(&unit->device,
"transaction failed: %s\n",
fw_rcode_string(rcode));
return -EIO;
}
msleep(ERROR_RETRY_DELAY_MS);
}
}
EXPORT_SYMBOL(snd_fw_transaction);
#define PROBE_DELAY_MS (2 * MSEC_PER_SEC)
/**
* snd_fw_schedule_registration - schedule work for sound card registration
* @unit: an instance for unit on IEEE 1394 bus
* @dwork: delayed work with callback function
*
* This function is not designed for general purposes. When new unit is
* connected to IEEE 1394 bus, the bus is under bus-reset state because of
* topological change. In this state, units tend to fail both of asynchronous
* and isochronous communication. To avoid this problem, this function is used
* to postpone sound card registration after the state. The callers must
* set up instance of delayed work in advance.
*/
void snd_fw_schedule_registration(struct fw_unit *unit,
struct delayed_work *dwork)
{
u64 now, delay;
now = get_jiffies_64();
delay = fw_parent_device(unit)->card->reset_jiffies
+ msecs_to_jiffies(PROBE_DELAY_MS);
if (time_after64(delay, now))
delay -= now;
else
delay = 0;
mod_delayed_work(system_wq, dwork, delay);
}
EXPORT_SYMBOL(snd_fw_schedule_registration);
MODULE_DESCRIPTION("FireWire audio helper functions");
MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>");
MODULE_LICENSE("GPL v2");
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