// 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 v2");