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 #define PROBE_DELAY_MS          (2 * MSEC_PER_SEC)
  71
  72 /**
  73  * snd_fw_schedule_registration - schedule work for sound card registration
  74  * @unit: an instance for unit on IEEE 1394 bus
  75  * @dwork: delayed work with callback function
  76  *
  77  * This function is not designed for general purposes. When new unit is
  78  * connected to IEEE 1394 bus, the bus is under bus-reset state because of
  79  * topological change. In this state, units tend to fail both of asynchronous
  80  * and isochronous communication. To avoid this problem, this function is used
  81  * to postpone sound card registration after the state. The callers must
  82  * set up instance of delayed work in advance.
  83  */
  84 void snd_fw_schedule_registration(struct fw_unit *unit,
  85                                   struct delayed_work *dwork)
  86 {
  87         u64 now, delay;
  88
  89         now = get_jiffies_64();
  90         delay = fw_parent_device(unit)->card->reset_jiffies
  91                                         + msecs_to_jiffies(PROBE_DELAY_MS);
  92
  93         if (time_after64(delay, now))
  94                 delay -= now;
  95         else
  96                 delay = 0;
  97
  98         mod_delayed_work(system_wq, dwork, delay);
  99 }
 100 EXPORT_SYMBOL(snd_fw_schedule_registration);
 101
 102 static void async_midi_port_callback(struct fw_card *card, int rcode,
 103                                      void *data, size_t length,
 104                                      void *callback_data)
 105 {
 106         struct snd_fw_async_midi_port *port = callback_data;
 107         struct snd_rawmidi_substream *substream = ACCESS_ONCE(port->substream);
 108
 109         /* This port is closed. */
 110         if (substream == NULL)
 111                 return;
 112
 113         if (rcode == RCODE_COMPLETE)
 114                 snd_rawmidi_transmit_ack(substream, port->consume_bytes);
 115         else if (!rcode_is_permanent_error(rcode))
 116                 /* To start next transaction immediately for recovery. */
 117                 port->next_ktime = 0;
 118         else
 119                 /* Don't continue processing. */
 120                 port->error = true;
 121
 122         port->idling = true;
 123
 124         if (!snd_rawmidi_transmit_empty(substream))
 125                 schedule_work(&port->work);
 126 }
 127
 128 static void midi_port_work(struct work_struct *work)
 129 {
 130         struct snd_fw_async_midi_port *port =
 131                         container_of(work, struct snd_fw_async_midi_port, work);
 132         struct snd_rawmidi_substream *substream = ACCESS_ONCE(port->substream);
 133         int generation;
 134         int type;
 135
 136         /* Under transacting or error state. */
 137         if (!port->idling || port->error)
 138                 return;
 139
 140         /* Nothing to do. */
 141         if (substream == NULL || snd_rawmidi_transmit_empty(substream))
 142                 return;
 143
 144         /* Do it in next chance. */
 145         if (ktime_after(port->next_ktime, ktime_get())) {
 146                 schedule_work(&port->work);
 147                 return;
 148         }
 149
 150         /*
 151          * Fill the buffer. The callee must use snd_rawmidi_transmit_peek().
 152          * Later, snd_rawmidi_transmit_ack() is called.
 153          */
 154         memset(port->buf, 0, port->len);
 155         port->consume_bytes = port->fill(substream, port->buf);
 156         if (port->consume_bytes <= 0) {
 157                 /* Do it in next chance, immediately. */
 158                 if (port->consume_bytes == 0) {
 159                         port->next_ktime = 0;
 160                         schedule_work(&port->work);
 161                 } else {
 162                         /* Fatal error. */
 163                         port->error = true;
 164                 }
 165                 return;
 166         }
 167
 168         /* Calculate type of transaction. */
 169         if (port->len == 4)
 170                 type = TCODE_WRITE_QUADLET_REQUEST;
 171         else
 172                 type = TCODE_WRITE_BLOCK_REQUEST;
 173
 174         /* Set interval to next transaction. */
 175         port->next_ktime = ktime_add_ns(ktime_get(),
 176                                 port->consume_bytes * 8 * NSEC_PER_SEC / 31250);
 177
 178         /* Start this transaction. */
 179         port->idling = false;
 180
 181         /*
 182          * In Linux FireWire core, when generation is updated with memory
 183          * barrier, node id has already been updated. In this module, After
 184          * this smp_rmb(), load/store instructions to memory are completed.
 185          * Thus, both of generation and node id are available with recent
 186          * values. This is a light-serialization solution to handle bus reset
 187          * events on IEEE 1394 bus.
 188          */
 189         generation = port->parent->generation;
 190         smp_rmb();
 191
 192         fw_send_request(port->parent->card, &port->transaction, type,
 193                         port->parent->node_id, generation,
 194                         port->parent->max_speed, port->addr,
 195                         port->buf, port->len, async_midi_port_callback,
 196                         port);
 197 }
 198
 199 /**
 200  * snd_fw_async_midi_port_init - initialize asynchronous MIDI port structure
 201  * @port: the asynchronous MIDI port to initialize
 202  * @unit: the target of the asynchronous transaction
 203  * @addr: the address to which transactions are transferred
 204  * @len: the length of transaction
 205  * @fill: the callback function to fill given buffer, and returns the
 206  *             number of consumed bytes for MIDI message.
 207  *
 208  */
 209 int snd_fw_async_midi_port_init(struct snd_fw_async_midi_port *port,
 210                 struct fw_unit *unit, u64 addr, unsigned int len,
 211                 snd_fw_async_midi_port_fill fill)
 212 {
 213         port->len = DIV_ROUND_UP(len, 4) * 4;
 214         port->buf = kzalloc(port->len, GFP_KERNEL);
 215         if (port->buf == NULL)
 216                 return -ENOMEM;
 217
 218         port->parent = fw_parent_device(unit);
 219         port->addr = addr;
 220         port->fill = fill;
 221         port->idling = true;
 222         port->next_ktime = 0;
 223         port->error = false;
 224
 225         INIT_WORK(&port->work, midi_port_work);
 226
 227         return 0;
 228 }
 229 EXPORT_SYMBOL(snd_fw_async_midi_port_init);
 230
 231 /**
 232  * snd_fw_async_midi_port_destroy - free asynchronous MIDI port structure
 233  * @port: the asynchronous MIDI port structure
 234  */
 235 void snd_fw_async_midi_port_destroy(struct snd_fw_async_midi_port *port)
 236 {
 237         snd_fw_async_midi_port_finish(port);
 238         cancel_work_sync(&port->work);
 239         kfree(port->buf);
 240 }
 241 EXPORT_SYMBOL(snd_fw_async_midi_port_destroy);
 242
 243 MODULE_DESCRIPTION("FireWire audio helper functions");
 244 MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>");
 245 MODULE_LICENSE("GPL v2");