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