/* * 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");