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 20 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 * @flags: use %FW_FIXED_GENERATION and add the generation value to attempt the 24 * request only in that generation; use %FW_QUIET to suppress error 25 * messages 26 * 27 * Submits an asynchronous request to the target device, and waits for the 28 * response. The node ID and the current generation are derived from @unit. 29 * On a bus reset or an error, the transaction is retried a few times. 30 * Returns zero on success, or a negative error code. 31 */ 32 int snd_fw_transaction(struct fw_unit *unit, int tcode, 33 u64 offset, void *buffer, size_t length, 34 unsigned int flags) 35 { 36 struct fw_device *device = fw_parent_device(unit); 37 int generation, rcode, tries = 0; 38 39 generation = flags & FW_GENERATION_MASK; 40 for (;;) { 41 if (!(flags & FW_FIXED_GENERATION)) { 42 generation = device->generation; 43 smp_rmb(); /* node_id vs. generation */ 44 } 45 rcode = fw_run_transaction(device->card, tcode, 46 device->node_id, generation, 47 device->max_speed, offset, 48 buffer, length); 49 50 if (rcode == RCODE_COMPLETE) 51 return 0; 52 53 if (rcode == RCODE_GENERATION && (flags & FW_FIXED_GENERATION)) 54 return -EAGAIN; 55 56 if (rcode_is_permanent_error(rcode) || ++tries >= 3) { 57 if (!(flags & FW_QUIET)) 58 dev_err(&unit->device, 59 "transaction failed: %s\n", 60 fw_rcode_string(rcode)); 61 return -EIO; 62 } 63 64 msleep(ERROR_RETRY_DELAY_MS); 65 } 66 } 67 EXPORT_SYMBOL(snd_fw_transaction); 68 69 MODULE_DESCRIPTION("FireWire audio helper functions"); 70 MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>"); 71 MODULE_LICENSE("GPL v2"); 72