// SPDX-License-Identifier: GPL-2.0-only/* * miscellaneous helper functions * * Copyright (c) Clemens Ladisch <clemens@ladisch.de> */ #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); MODULE_DESCRIPTION("FireWire audio helper functions");MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>");MODULE_LICENSE("GPL");