// 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");