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 <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 static void async_midi_port_callback(struct fw_card *card, int rcode,
  71                                      void *data, size_t length,
  72                                      void *callback_data)
  73 {
  74         struct snd_fw_async_midi_port *port = callback_data;
  75         struct snd_rawmidi_substream *substream = ACCESS_ONCE(port->substream);
  76
  77         /* This port is closed. */
  78         if (substream == NULL)
  79                 return;
  80
  81         if (rcode == RCODE_COMPLETE)
  82                 snd_rawmidi_transmit_ack(substream, port->consume_bytes);
  83         else if (!rcode_is_permanent_error(rcode))
  84                 /* To start next transaction immediately for recovery. */
  85                 port->next_ktime = ktime_set(0, 0);
  86         else
  87                 /* Don't continue processing. */
  88                 port->error = true;
  89
  90         port->idling = true;
  91
  92         if (!snd_rawmidi_transmit_empty(substream))
  93                 schedule_work(&port->work);
  94 }
  95
  96 static void midi_port_work(struct work_struct *work)
  97 {
  98         struct snd_fw_async_midi_port *port =
  99                         container_of(work, struct snd_fw_async_midi_port, work);
 100         struct snd_rawmidi_substream *substream = ACCESS_ONCE(port->substream);
 101         int generation;
 102         int type;
 103
 104         /* Under transacting or error state. */
 105         if (!port->idling || port->error)
 106                 return;
 107
 108         /* Nothing to do. */
 109         if (substream == NULL || snd_rawmidi_transmit_empty(substream))
 110                 return;
 111
 112         /* Do it in next chance. */
 113         if (ktime_after(port->next_ktime, ktime_get())) {
 114                 schedule_work(&port->work);
 115                 return;
 116         }
 117
 118         /*
 119          * Fill the buffer. The callee must use snd_rawmidi_transmit_peek().
 120          * Later, snd_rawmidi_transmit_ack() is called.
 121          */
 122         memset(port->buf, 0, port->len);
 123         port->consume_bytes = port->fill(substream, port->buf);
 124         if (port->consume_bytes <= 0) {
 125                 /* Do it in next chance, immediately. */
 126                 if (port->consume_bytes == 0) {
 127                         port->next_ktime = ktime_set(0, 0);
 128                         schedule_work(&port->work);
 129                 } else {
 130                         /* Fatal error. */
 131                         port->error = true;
 132                 }
 133                 return;
 134         }
 135
 136         /* Calculate type of transaction. */
 137         if (port->len == 4)
 138                 type = TCODE_WRITE_QUADLET_REQUEST;
 139         else
 140                 type = TCODE_WRITE_BLOCK_REQUEST;
 141
 142         /* Set interval to next transaction. */
 143         port->next_ktime = ktime_add_ns(ktime_get(),
 144                                 port->consume_bytes * 8 * NSEC_PER_SEC / 31250);
 145
 146         /* Start this transaction. */
 147         port->idling = false;
 148
 149         /*
 150          * In Linux FireWire core, when generation is updated with memory
 151          * barrier, node id has already been updated. In this module, After
 152          * this smp_rmb(), load/store instructions to memory are completed.
 153          * Thus, both of generation and node id are available with recent
 154          * values. This is a light-serialization solution to handle bus reset
 155          * events on IEEE 1394 bus.
 156          */
 157         generation = port->parent->generation;
 158         smp_rmb();
 159
 160         fw_send_request(port->parent->card, &port->transaction, type,
 161                         port->parent->node_id, generation,
 162                         port->parent->max_speed, port->addr,
 163                         port->buf, port->len, async_midi_port_callback,
 164                         port);
 165 }
 166
 167 /**
 168  * snd_fw_async_midi_port_init - initialize asynchronous MIDI port structure
 169  * @port: the asynchronous MIDI port to initialize
 170  * @unit: the target of the asynchronous transaction
 171  * @addr: the address to which transactions are transferred
 172  * @len: the length of transaction
 173  * @fill: the callback function to fill given buffer, and returns the
 174  *             number of consumed bytes for MIDI message.
 175  *
 176  */
 177 int snd_fw_async_midi_port_init(struct snd_fw_async_midi_port *port,
 178                 struct fw_unit *unit, u64 addr, unsigned int len,
 179                 snd_fw_async_midi_port_fill fill)
 180 {
 181         port->len = DIV_ROUND_UP(len, 4) * 4;
 182         port->buf = kzalloc(port->len, GFP_KERNEL);
 183         if (port->buf == NULL)
 184                 return -ENOMEM;
 185
 186         port->parent = fw_parent_device(unit);
 187         port->addr = addr;
 188         port->fill = fill;
 189         port->idling = true;
 190         port->next_ktime = ktime_set(0, 0);
 191         port->error = false;
 192
 193         INIT_WORK(&port->work, midi_port_work);
 194
 195         return 0;
 196 }
 197 EXPORT_SYMBOL(snd_fw_async_midi_port_init);
 198
 199 /**
 200  * snd_fw_async_midi_port_destroy - free asynchronous MIDI port structure
 201  * @port: the asynchronous MIDI port structure
 202  */
 203 void snd_fw_async_midi_port_destroy(struct snd_fw_async_midi_port *port)
 204 {
 205         snd_fw_async_midi_port_finish(port);
 206         cancel_work_sync(&port->work);
 207         kfree(port->buf);
 208 }
 209 EXPORT_SYMBOL(snd_fw_async_midi_port_destroy);
 210
 211 MODULE_DESCRIPTION("FireWire audio helper functions");
 212 MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>");
 213 MODULE_LICENSE("GPL v2");