73 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*3 * miscellaneous helper functions4 *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 2016 17/**18 * snd_fw_transaction - send a request and wait for its completion19 * @unit: the driver's unit on the target device20 * @tcode: the transaction code21 * @offset: the address in the target's address space22 * @buffer: input/output data23 * @length: length of @buffer24 * @flags: use %FW_FIXED_GENERATION and add the generation value to attempt the25 * request only in that generation; use %FW_QUIET to suppress error26 * messages27 *28 * Submits an asynchronous request to the target device, and waits for the29 * 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");73