LXR linux/sound/firewire/lib.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * miscellaneous helper functions
   4 *
   5 * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
   6 */
   7
   8#include <linux/delay.h>
   9#include <linux/device.h>
  10#include <linux/firewire.h>
  11#include <linux/module.h>
  12#include <linux/slab.h>
  13#include "lib.h"
  14
  15#define ERROR_RETRY_DELAY_MS    20
  16
  17/**
  18 * snd_fw_transaction - send a request and wait for its completion
  19 * @unit: the driver's unit on the target device
  20 * @tcode: the transaction code
  21 * @offset: the address in the target's address space
  22 * @buffer: input/output data
  23 * @length: length of @buffer
  24 * @flags: use %FW_FIXED_GENERATION and add the generation value to attempt the
  25 *         request only in that generation; use %FW_QUIET to suppress error
  26 *         messages
  27 *
  28 * Submits an asynchronous request to the target device, and waits for the
  29 * response.  The node ID and the current generation are derived from @unit.
  30 * On a bus reset or an error, the transaction is retried a few times.
  31 * Returns zero on success, or a negative error code.
  32 */
  33int snd_fw_transaction(struct fw_unit *unit, int tcode,
  34                       u64 offset, void *buffer, size_t length,
  35                       unsigned int flags)
  36{
  37        struct fw_device *device = fw_parent_device(unit);
  38        int generation, rcode, tries = 0;
  39
  40        generation = flags & FW_GENERATION_MASK;
  41        for (;;) {
  42                if (!(flags & FW_FIXED_GENERATION)) {
  43                        generation = device->generation;
  44                        smp_rmb(); /* node_id vs. generation */
  45                }
  46                rcode = fw_run_transaction(device->card, tcode,
  47                                           device->node_id, generation,
  48                                           device->max_speed, offset,
  49                                           buffer, length);
  50
  51                if (rcode == RCODE_COMPLETE)
  52                        return 0;
  53
  54                if (rcode == RCODE_GENERATION && (flags & FW_FIXED_GENERATION))
  55                        return -EAGAIN;
  56
  57                if (rcode_is_permanent_error(rcode) || ++tries >= 3) {
  58                        if (!(flags & FW_QUIET))
  59                                dev_err(&unit->device,
  60                                        "transaction failed: %s\n",
  61                                        fw_rcode_string(rcode));
  62                        return -EIO;
  63                }
  64
  65                msleep(ERROR_RETRY_DELAY_MS);
  66        }
  67}
  68EXPORT_SYMBOL(snd_fw_transaction);
  69
  70MODULE_DESCRIPTION("FireWire audio helper functions");
  71MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>");
  72MODULE_LICENSE("GPL v2");
  73