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 */ 33 int 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 } 68 EXPORT_SYMBOL(snd_fw_transaction); 69 70 MODULE_DESCRIPTION("FireWire audio helper functions"); 71 MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>"); 72 MODULE_LICENSE("GPL v2"); 73