sound/firewire/lib.c

   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  * rcode_string - convert a firewire result code to a string
  18  * @rcode: the result
  19  */
  20 const char *rcode_string(unsigned int rcode)
  21 {
  22         static const char *const names[] = {
  23                 [RCODE_COMPLETE]        = "complete",
  24                 [RCODE_CONFLICT_ERROR]  = "conflict error",
  25                 [RCODE_DATA_ERROR]      = "data error",
  26                 [RCODE_TYPE_ERROR]      = "type error",
  27                 [RCODE_ADDRESS_ERROR]   = "address error",
  28                 [RCODE_SEND_ERROR]      = "send error",
  29                 [RCODE_CANCELLED]       = "cancelled",
  30                 [RCODE_BUSY]            = "busy",
  31                 [RCODE_GENERATION]      = "generation",
  32                 [RCODE_NO_ACK]          = "no ack",
  33         };
  34
  35         if (rcode < ARRAY_SIZE(names) && names[rcode])
  36                 return names[rcode];
  37         else
  38                 return "unknown";
  39 }
  40 EXPORT_SYMBOL(rcode_string);
  41
  42 /**
  43  * snd_fw_transaction - send a request and wait for its completion
  44  * @unit: the driver's unit on the target device
  45  * @tcode: the transaction code
  46  * @offset: the address in the target's address space
  47  * @buffer: input/output data
  48  * @length: length of @buffer
  49  *
  50  * Submits an asynchronous request to the target device, and waits for the
  51  * response.  The node ID and the current generation are derived from @unit.
  52  * On a bus reset or an error, the transaction is retried a few times.
  53  * Returns zero on success, or a negative error code.
  54  */
  55 int snd_fw_transaction(struct fw_unit *unit, int tcode,
  56                        u64 offset, void *buffer, size_t length)
  57 {
  58         struct fw_device *device = fw_parent_device(unit);
  59         int generation, rcode, tries = 0;
  60
  61         for (;;) {
  62                 generation = device->generation;
  63                 smp_rmb(); /* node_id vs. generation */
  64                 rcode = fw_run_transaction(device->card, tcode,
  65                                            device->node_id, generation,
  66                                            device->max_speed, offset,
  67                                            buffer, length);
  68
  69                 if (rcode == RCODE_COMPLETE)
  70                         return 0;
  71
  72                 if (rcode_is_permanent_error(rcode) || ++tries >= 3) {
  73                         dev_err(&unit->device, "transaction failed: %s\n",
  74                                 rcode_string(rcode));
  75                         return -EIO;
  76                 }
  77
  78                 msleep(ERROR_RETRY_DELAY_MS);
  79         }
  80 }
  81 EXPORT_SYMBOL(snd_fw_transaction);
  82
  83 MODULE_DESCRIPTION("FireWire audio helper functions");
  84 MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>");
  85 MODULE_LICENSE("GPL v2");