Lines Matching +full:has +full:- +full:chip +full:- +full:id
11 Architecture) <http://www.alsa-project.org/>`__ driver. The document
19 low-level driver implementation details. It only describes the standard
26 -------
56 --------------
60 sub-directories contain different modules and are dependent upon the
74 This directory and its sub-directories are for the ALSA sequencer. This
76 as snd-seq-midi, snd-seq-virmidi, etc. They are compiled only when
85 -----------------
88 to be exported to user-space, or included by several files in different
94 -----------------
97 architectures. They are hence supposed not to be architecture-specific.
99 in this directory. In the sub-directories, there is code for components
105 The MPU401 and MPU401-UART modules are stored here.
110 The OPL3 and OPL4 FM-synth stuff is found here.
113 -------------
117 Although there is a standard i2c layer on Linux, ALSA has its own i2c
122 ---------------
124 This contains the synth middle-level modules.
127 ``synth/emux`` sub-directory.
130 -------------
132 This directory and its sub-directories hold the top-level card modules
137 their own sub-directory (e.g. emu10k1, ice1712).
140 -------------
142 This directory and its sub-directories hold the top-level card modules
146 -------------------------------
148 They are used for top-level card modules which are specific to one of
152 -------------
154 This directory contains the USB-audio driver.
155 The USB MIDI driver is integrated in the usb-audio driver.
158 ----------------
165 -------------
167 This directory contains the codes for ASoC (ALSA System on Chip)
171 -------------
174 At the time of writing, all code has been removed except for dmasound
182 -------
186 - define the PCI ID table (see the section `PCI Entries`_).
188 - create ``probe`` callback.
190 - create ``remove`` callback.
192 - create a struct pci_driver structure
195 - create an ``init`` function just calling the
199 - create an ``exit`` function to call the
203 -----------------
221 static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;
224 /* definition of the chip-specific record */
232 /* chip-specific destructor
235 static int snd_mychip_free(struct mychip *chip)
240 /* component-destructor
245 return snd_mychip_free(device->device_data);
248 /* chip-specific constructor
255 struct mychip *chip;
268 /* allocate a chip-specific data with zero filled */
269 chip = kzalloc(sizeof(*chip), GFP_KERNEL);
270 if (chip == NULL)
271 return -ENOMEM;
273 chip->card = card;
280 err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, &ops);
282 snd_mychip_free(chip);
286 *rchip = chip;
290 /* constructor -- see "Driver Constructor" sub-section */
296 struct mychip *chip;
301 return -ENODEV;
304 return -ENOENT;
308 err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
314 err = snd_mychip_create(card, pci, &chip);
319 strcpy(card->driver, "My Chip");
320 strcpy(card->shortname, "My Own Chip 123");
321 sprintf(card->longname, "%s at 0x%lx irq %i",
322 card->shortname, chip->port, chip->irq);
342 /* destructor -- see the "Destructor" sub-section */
351 ------------------
354 ``probe`` callback and other component-constructors which are called
368 return -ENODEV;
371 return -ENOENT;
390 err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
402 struct mychip *chip;
404 err = snd_mychip_create(card, pci, &chip);
423 4) Set the driver ID and name strings.
428 strcpy(card->driver, "My Chip");
429 strcpy(card->shortname, "My Own Chip 123");
430 sprintf(card->longname, "%s at 0x%lx irq %i",
431 card->shortname, chip->port, chip->irq);
433 The driver field holds the minimal ID string of the chip. This is used
434 by alsa-lib's configurator, so keep it simple but unique. Even the
436 functionality of each chip type.
446 `MPU-401 <MIDI (MPU401-UART) Interface_>`__), and other interfaces.
472 remove callback and power-management callbacks, too.
475 ----------
493 ------------
521 -------------
527 MIDI, synthesizer, and so on. Also, the card record holds the ID and the
529 the power-management states and hotplug disconnections. The component
538 err = snd_card_new(&pci->dev, index, id, module, extra_size, &card);
542 card-index number, the id string, the module pointer (usually
543 ``THIS_MODULE``), the size of extra-data space, and the pointer to
545 card->private_data for the chip-specific data. Note that these data are
549 device. For PCI devices, typically ``&pci->`` is passed there.
552 ----------
558 Each such instance has one component entry.
563 snd_device_new(card, SNDRV_DEV_XXX, chip, &ops);
565 This takes the card pointer, the device-level (``SNDRV_DEV_XXX``), the
566 data pointer, and the callback pointers (``&ops``). The device-level
568 de-registration. For most components, the device-level is already
569 defined. For a user-defined component, you can use
574 argument. This pointer (``chip`` in the above example) is used as the
577 Each pre-defined ALSA component such as AC97 and PCM calls
585 example will show an implementation of chip-specific data.
587 Chip-Specific Data
588 ------------------
590 Chip-specific information, e.g. the I/O port address, its resource
591 pointer, or the irq number, is stored in the chip-specific record::
598 In general, there are two ways of allocating the chip record.
603 As mentioned above, you can pass the extra-data-length to the 5th
606 err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
609 struct mychip is the type of the chip record.
615 struct mychip *chip = card->private_data;
627 struct mychip *chip;
628 err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
631 chip = kzalloc(sizeof(*chip), GFP_KERNEL);
633 The chip record should have the field to hold the card pointer at least,
643 Then, set the card pointer in the returned chip instance::
645 chip->card = card;
647 Next, initialize the fields, and register this chip record as a
648 low-level device with a specified ``ops``::
654 snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, &ops);
656 :c:func:`snd_mychip_dev_free()` is the device-destructor
661 return snd_mychip_free(device->device_data);
674 ------------------------
695 -----------------
697 In this section, we'll complete the chip-specific constructor,
708 static int snd_mychip_free(struct mychip *chip)
714 if (chip->irq >= 0)
715 free_irq(chip->irq, chip);
717 pci_release_regions(chip->pci);
719 pci_disable_device(chip->pci);
721 kfree(chip);
725 /* chip-specific constructor */
730 struct mychip *chip;
747 return -ENXIO;
750 chip = kzalloc(sizeof(*chip), GFP_KERNEL);
751 if (chip == NULL) {
753 return -ENOMEM;
757 chip->card = card;
758 chip->pci = pci;
759 chip->irq = -1;
762 err = pci_request_regions(pci, "My Chip");
764 kfree(chip);
768 chip->port = pci_resource_start(pci, 0);
769 if (request_irq(pci->irq, snd_mychip_interrupt,
770 IRQF_SHARED, KBUILD_MODNAME, chip)) {
771 printk(KERN_ERR "cannot grab irq %d\n", pci->irq);
772 snd_mychip_free(chip);
773 return -EBUSY;
775 chip->irq = pci->irq;
776 card->sync_irq = chip->irq;
778 /* (2) initialization of the chip hardware */
781 err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, &ops);
783 snd_mychip_free(chip);
787 *rchip = chip;
826 ------------
847 return -ENXIO;
852 -------------------
858 Now assume that the PCI device has an I/O port with 8 bytes and an
873 this number to -1 before actual allocation, since irq 0 is valid. The
880 err = pci_request_regions(pci, "My Chip");
882 kfree(chip);
886 chip->port = pci_resource_start(pci, 0);
889 The returned value, ``chip->res_port``, is allocated via
896 if (request_irq(pci->irq, snd_mychip_interrupt,
897 IRQF_SHARED, KBUILD_MODNAME, chip)) {
898 printk(KERN_ERR "cannot grab irq %d\n", pci->irq);
899 snd_mychip_free(chip);
900 return -EBUSY;
902 chip->irq = pci->irq;
906 ``chip->irq`` should be defined only when :c:func:`request_irq()`
913 passed to the interrupt handler. Usually, the chip-specific record is
922 struct mychip *chip = dev_id;
927 After requesting the IRQ, you can passed it to ``card->sync_irq``
930 card->irq = chip->irq;
941 To release the resources, the “check-and-release” method is a safer way.
944 if (chip->irq >= 0)
945 free_irq(chip->irq, chip);
948 ``chip->irq`` with a negative value (e.g. -1), so that you can check
958 pci_release_regions(chip->pci);
964 chip->res_port, the release procedure looks like::
966 release_and_free_resource(chip->res_port);
971 And finally, release the chip-specific record::
973 kfree(chip);
977 before the initialization of the chip is completed. It would be better
981 When the chip-data is assigned to the card using
985 have to stop PCMs, etc. explicitly, but just call low-level hardware
988 The management of a memory-mapped region is almost as same as the
999 err = pci_request_regions(pci, "My Chip");
1001 kfree(chip);
1004 chip->iobase_phys = pci_resource_start(pci, 0);
1005 chip->iobase_virt = ioremap(chip->iobase_phys,
1010 static int snd_mychip_free(struct mychip *chip)
1013 if (chip->iobase_virt)
1014 iounmap(chip->iobase_virt);
1016 pci_release_regions(chip->pci);
1023 err = pci_request_regions(pci, "My Chip");
1025 kfree(chip);
1028 chip->iobase_virt = pci_iomap(pci, 0, 0);
1034 -----------
1038 this chipset. It's a table of PCI vendor/device ID number, and some
1059 all-zero entry.
1099 -------
1102 for each driver to implement the low-level functions to access its
1117 support multiple playback functions. For example, emu10k1 has a PCM
1126 -----------------
1175 struct mychip *chip = snd_pcm_substream_chip(substream);
1176 struct snd_pcm_runtime *runtime = substream->runtime;
1178 runtime->hw = snd_mychip_playback_hw;
1179 /* more hardware-initialization will be done here */
1187 struct mychip *chip = snd_pcm_substream_chip(substream);
1188 /* the hardware-specific codes will be here */
1197 struct mychip *chip = snd_pcm_substream_chip(substream);
1198 struct snd_pcm_runtime *runtime = substream->runtime;
1200 runtime->hw = snd_mychip_capture_hw;
1201 /* more hardware-initialization will be done here */
1209 struct mychip *chip = snd_pcm_substream_chip(substream);
1210 /* the hardware-specific codes will be here */
1219 /* the hardware-specific codes will be here */
1227 /* the hardware-specific codes will be here */
1235 struct mychip *chip = snd_pcm_substream_chip(substream);
1236 struct snd_pcm_runtime *runtime = substream->runtime;
1241 mychip_set_sample_format(chip, runtime->format);
1242 mychip_set_sample_rate(chip, runtime->rate);
1243 mychip_set_channels(chip, runtime->channels);
1244 mychip_set_dma_setup(chip, runtime->dma_addr,
1245 chip->buffer_size,
1246 chip->period_size);
1264 return -EINVAL;
1272 struct mychip *chip = snd_pcm_substream_chip(substream);
1276 current_ptr = mychip_get_hw_pointer(chip);
1307 static int snd_mychip_new_pcm(struct mychip *chip)
1312 err = snd_pcm_new(chip->card, "My Chip", 0, 1, 1, &pcm);
1315 pcm->private_data = chip;
1316 strcpy(pcm->name, "My Chip");
1317 chip->pcm = pcm;
1323 /* pre-allocation of buffers */
1326 &chip->pci->dev,
1333 ---------------
1338 static int snd_mychip_new_pcm(struct mychip *chip)
1343 err = snd_pcm_new(chip->card, "My Chip", 0, 1, 1, &pcm);
1346 pcm->private_data = chip;
1347 strcpy(pcm->name, "My Chip");
1348 chip->pcm = pcm;
1355 the second is the ID string.
1367 If a chip supports multiple playbacks or captures, you can specify more
1374 int index = substream->number;
1398 After setting the operators, you probably will want to pre-allocate the
1403 &chip->pci->dev,
1411 ``pcm->info_flags``. The available values are defined as
1414 half-duplex, specify it like this::
1416 pcm->info_flags = SNDRV_PCM_INFO_HALF_DUPLEX;
1420 -----------------------
1428 destructor function to ``pcm->private_free``::
1432 struct mychip *chip = snd_pcm_chip(pcm);
1434 kfree(chip->my_private_pcm_data);
1439 static int snd_mychip_new_pcm(struct mychip *chip)
1444 chip->my_private_pcm_data = kmalloc(...);
1446 pcm->private_data = chip;
1447 pcm->private_free = mychip_pcm_free;
1453 Runtime Pointer - The Chest of PCM Information
1454 ----------------------------------------------
1458 ``substream->runtime``. This runtime pointer holds most information you
1466 /* -- Status -- */
1474 /* -- HW params -- */
1492 /* -- SW params -- */
1501 snd_pcm_uframes_t stop_threshold; /* - stop playback */
1502 snd_pcm_uframes_t silence_threshold; /* - pre-fill buffer with silence */
1503 snd_pcm_uframes_t silence_size; /* max size of silence pre-fill; when >= boundary,
1507 /* internal data of auto-silencer */
1511 snd_pcm_sync_id_t sync; /* hardware synchronization ID */
1513 /* -- mmap -- */
1518 /* -- locking / scheduling -- */
1524 /* -- private section -- */
1528 /* -- hardware description -- */
1532 /* -- timer -- */
1535 /* -- DMA -- */
1543 /* -- OSS things -- */
1550 records are supposed to be read-only. Only the PCM middle-layer changes
1566 (``runtime->hw``) as you need. For example, if the maximum number of
1567 channels is 1 only on some chip models, you can still use the same
1570 struct snd_pcm_runtime *runtime = substream->runtime;
1572 runtime->hw = snd_mychip_playback_hw; /* common definition */
1573 if (chip->model == VERY_OLD_ONE)
1574 runtime->hw.channels_max = 1;
1596 - The ``info`` field contains the type and capabilities of this
1602 interleaved or the non-interleaved formats, the
1623 need to check the linked-list of PCM substreams in the trigger
1626 - The ``formats`` field contains the bit-flags of supported formats
1629 little-endian format is specified.
1631 - The ``rates`` field contains the bit-flags of supported rates
1632 (``SNDRV_PCM_RATE_XXX``). When the chip supports continuous rates,
1633 pass the ``CONTINUOUS`` bit additionally. The pre-defined rate bits
1634 are provided only for typical rates. If your chip supports
1638 - ``rate_min`` and ``rate_max`` define the minimum and maximum sample
1641 - ``channels_min`` and ``channels_max`` define, as you might have already
1644 - ``buffer_bytes_max`` defines the maximum buffer size in
1661 - There is also a field ``fifo_size``. This specifies the size of the
1663 in the alsa-lib. So, you can ignore this field.
1672 alsa-lib. There are many fields copied from hw_params and sw_params
1679 channels \* samples-size``. For conversion between frames and bytes,
1683 period_bytes = frames_to_bytes(runtime, runtime->period_size);
1715 The running status can be referred via ``runtime->status``. This is
1718 DMA hardware pointer via ``runtime->status->hw_ptr``.
1720 The DMA application pointer can be referred via ``runtime->control``,
1728 ``runtime->private_data``. Usually, this is done in the `PCM open
1729 callback`_. Don't mix this with ``pcm->private_data``. The
1730 ``pcm->private_data`` usually points to the chip instance assigned
1732 ``runtime->private_data``
1741 substream->runtime->private_data = data;
1749 ---------
1753 error number such as ``-EINVAL``. To choose an appropriate error
1758 struct snd_pcm_substream pointer. To retrieve the chip
1763 struct mychip *chip = snd_pcm_substream_chip(substream);
1767 The macro reads ``substream->private_data``, which is a copy of
1768 ``pcm->private_data``. You can override the former if you need to
1771 capture directions, because it uses two different codecs (SB- and
1772 AD-compatible) for different directions.
1783 At least, here you have to initialize the ``runtime->hw``
1788 struct mychip *chip = snd_pcm_substream_chip(substream);
1789 struct snd_pcm_runtime *runtime = substream->runtime;
1791 runtime->hw = snd_mychip_playback_hw;
1795 where ``snd_mychip_playback_hw`` is the pre-defined hardware
1820 kfree(substream->runtime->private_data);
1859 DMA buffers have been pre-allocated. See the section `Buffer Types`_
1871 Another note is that this callback is non-atomic (schedulable) by
1873 because the ``trigger`` callback is atomic (non-schedulable). That is,
1874 mutexes or any schedule-related functions are not available in the
1896 pre-allocated pool, you can use the standard API function
1914 Note that this callback is non-atomic. You can use
1915 schedule-related functions safely in this callback.
1918 the runtime record, ``substream->runtime``. For example, to get the
1919 current rate, format or channels, access to ``runtime->rate``,
1920 ``runtime->format`` or ``runtime->channels``, respectively. The
1922 ``runtime->dma_area``. The buffer and period sizes are in
1923 ``runtime->buffer_size`` and ``runtime->period_size``, respectively.
1949 return -EINVAL;
1960 power-management status is changed. Obviously, the ``SUSPEND`` and
1990 the ``card->sync_irq`` field to the returned interrupt number after
1995 to clear ``card->sync_irq``, as the card itself is being released.
1997 ``card->sync_irq`` in the driver code unless the driver re-acquires
1998 the IRQ. When the driver frees and re-acquires the IRQ dynamically
1999 (e.g. for suspend/resume), it needs to clear and re-set
2000 ``card->sync_irq`` again appropriately.
2011 frames, ranging from 0 to ``buffer_size - 1``.
2013 This is usually called from the buffer-update routine in the PCM
2029 buffer is non-contiguous on both physical and virtual memory spaces,
2032 If these two callbacks are defined, copy and set-silence operations
2041 emu10k1-fx and cs46xx need to track the current ``appl_ptr`` for the
2045 return value is ``-EPIPE``, PCM core treats that as a buffer XRUN,
2056 You need no special callback for the standard SG-buffer or vmalloc-
2064 memory-mapped, instead of using the standard helper.
2066 device-specific issues), implement everything here as you like.
2070 ---------------------
2090 from the chip instance. For example, define ``substream`` field in the
2091 chip record to hold the current running substream pointer, and set the
2105 struct mychip *chip = dev_id;
2106 spin_lock(&chip->lock);
2108 if (pcm_irq_invoked(chip)) {
2110 spin_unlock(&chip->lock);
2111 snd_pcm_period_elapsed(chip->substream);
2112 spin_lock(&chip->lock);
2116 spin_unlock(&chip->lock);
2143 struct mychip *chip = dev_id;
2144 spin_lock(&chip->lock);
2146 if (pcm_irq_invoked(chip)) {
2149 last_ptr = get_hw_ptr(chip);
2153 if (last_ptr < chip->last_ptr)
2154 size = runtime->buffer_size + last_ptr
2155 - chip->last_ptr;
2157 size = last_ptr - chip->last_ptr;
2159 chip->last_ptr = last_ptr;
2161 chip->size += size;
2163 if (chip->size >= runtime->period_size) {
2165 chip->size %= runtime->period_size;
2167 spin_unlock(&chip->lock);
2169 spin_lock(&chip->lock);
2174 spin_unlock(&chip->lock);
2183 In both cases, even if more than one period has elapsed, you don't have
2189 ---------
2193 usually avoided via spin-locks, mutexes or semaphores. In general, if a
2194 race condition can happen in an interrupt handler, it has to be managed
2201 example, the ``hw_params`` callback is non-atomic, while the ``trigger``
2216 However, it is possible to request all PCM operations to be non-atomic.
2218 non-atomic contexts. For example, the function
2221 interrupt handler, this call can be in non-atomic context, too. In such
2225 functions safely in a non-atomic
2236 -----------
2257 err = snd_pcm_hw_constraint_list(substream->runtime, 0,
2281 if (f->bits[0] == SNDRV_PCM_FMTBIT_S16_LE) {
2292 snd_pcm_hw_rule_add(substream->runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS,
2294 SNDRV_PCM_HW_PARAM_FORMAT, -1);
2310 if (c->min < 2) {
2320 snd_pcm_hw_rule_add(substream->runtime, 0, SNDRV_PCM_HW_PARAM_FORMAT,
2322 SNDRV_PCM_HW_PARAM_CHANNELS, -1);
2335 snd_pcm_hw_constraint_integer(substream->runtime,
2350 -------
2353 which are accessed from user-space. Its most important use is the mixer
2357 ALSA has a well-defined AC97 control module. If your chip supports only
2364 ----------------------
2393 its name. There are pre-defined standard control names. The details
2420 -------------
2427 pre-defined sources.
2450 Tone-controls
2453 tone-control switch and volumes are specified like “Tone Control - XXX”,
2454 e.g. “Tone Control - Switch”, “Tone Control - Bass”, “Tone Control -
2460 3D-control switches and volumes are specified like “3D Control - XXX”,
2461 e.g. “3D Control - Switch”, “3D Control - Center”, “3D Control - Space”.
2466 Mic-boost switch is set as “Mic Boost” or “Mic Boost (6dB)”.
2469 ``Documentation/sound/designs/control-names.rst``.
2472 ------------
2480 When the control is read-only, pass ``SNDRV_CTL_ELEM_ACCESS_READ``
2482 Similarly, when the control is write-only (although it's a rare case),
2491 When the control may be updated, but currently has no effect on anything,
2498 -----------------
2512 uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
2513 uinfo->count = 1;
2514 uinfo->value.integer.min = 0;
2515 uinfo->value.integer.max = 1;
2537 uinfo->type = SNDRV_CTL_ELEM_TYPE_ENUMERATED;
2538 uinfo->count = 1;
2539 uinfo->value.enumerated.items = 4;
2540 if (uinfo->value.enumerated.item > 3)
2541 uinfo->value.enumerated.item = 3;
2542 strcpy(uinfo->value.enumerated.name,
2543 texts[uinfo->value.enumerated.item]);
2575 can be returned to user-space.
2582 struct mychip *chip = snd_kcontrol_chip(kcontrol);
2583 ucontrol->value.integer.value[0] = get_some_value(chip);
2591 register offset, the bit-shift and the bit-mask. The ``private_value``
2601 int reg = kcontrol->private_value & 0xff;
2602 int shift = (kcontrol->private_value >> 16) & 0xff;
2603 int mask = (kcontrol->private_value >> 24) & 0xff;
2608 control has more than one element, i.e. ``count > 1``. In the example
2615 This callback is used to write a value coming from user-space.
2622 struct mychip *chip = snd_kcontrol_chip(kcontrol);
2624 if (chip->current_value !=
2625 ucontrol->value.integer.value[0]) {
2626 change_current_value(chip,
2627 ucontrol->value.integer.value[0]);
2639 As in the ``get`` callback, when the control has more than one
2645 All these three callbacks are not-atomic.
2648 -------------------
2656 err = snd_ctl_add(card, snd_ctl_new1(&my_control, chip));
2661 and chip is the object pointer to be passed to kcontrol->private_data which
2669 -------------------
2676 This function takes the card pointer, the event-mask, and the control id
2677 pointer for the notification. The event-mask specifies the types of
2679 values is notified. The id pointer is the pointer of struct snd_ctl_elem_id
2684 --------
2692 static DECLARE_TLV_DB_SCALE(db_scale_my_control, -4050, 150, 0);
2723 -------
2725 The ALSA AC97 codec layer is a well-defined one, and you don't have to
2726 write much code to control it. Only low-level control routines are
2730 -----------------
2743 struct mychip *chip = ac97->private_data;
2752 struct mychip *chip = ac97->private_data;
2757 static int snd_mychip_ac97(struct mychip *chip)
2767 err = snd_ac97_bus(chip->card, 0, &ops, NULL, &bus);
2771 ac97.private_data = chip;
2772 return snd_ac97_mixer(bus, &ac97, &chip->ac97);
2777 ----------------
2799 ac97.private_data = chip;
2800 snd_ac97_mixer(bus, &ac97, &chip->ac97);
2802 where chip->ac97 is a pointer to a newly created ``ac97_t``
2803 instance. In this case, the chip pointer is set as the private data,
2804 so that the read/write callback functions can refer to this chip
2805 instance. This instance is not necessarily stored in the chip
2811 --------------
2815 hardware low-level codes.
2823 struct mychip *chip = ac97->private_data;
2828 Here, the chip can be cast from ``ac97->private_data``.
2837 These callbacks are non-atomic like the control API callbacks.
2841 The ``reset`` callback is used to reset the codec. If the chip
2845 initialization of the codec. If the chip requires the extra waiting
2852 --------------------------------
2863 value has been already set, while :c:func:`snd_ac97_write()`
2893 ----------------
2896 (to save a quartz!). In this case, change the field ``bus->clock`` to
2901 ----------
2904 ``/proc/asound/card0/codec97#0/ac97#0-0`` and ``ac97#0-0+regs``. You
2909 ---------------
2916 callbacks for each codec or check ``ac97->num`` in the callback
2919 MIDI (MPU401-UART) Interface
2923 -------
2925 Many soundcards have built-in MIDI (MPU401-UART) interfaces. When the
2926 soundcard supports the standard MPU401-UART interface, most likely you
2927 can use the ALSA MPU401-UART API. The MPU401-UART API is defined in
2931 mpu401 stuff. For example, emu10k1 has its own mpu401 routines.
2934 ----------------
2949 The 4th argument is the I/O port address. Many backward-compatible
2951 PCI I/O region. It depends on the chip design.
2957 mpu401-uart layer will allocate the I/O ports by itself.
2972 If the MPU-401 interface shares its interrupt with the other logical
2981 need to cast ``rmidi->private_data`` to struct snd_mpu401 explicitly::
2984 mpu = rmidi->private_data;
2988 mpu->cport = my_own_control_port;
2993 -1 instead. For a MPU-401 device without an interrupt, a polling timer
2997 ----------------------
3005 interrupt handler when it has determined that a UART interrupt has
3012 snd_mpu401_uart_interrupt(irq, rmidi->private_data, regs);
3019 --------
3031 -------------------
3037 err = snd_rawmidi_new(chip->card, "MyMIDI", 0, outs, ins, &rmidi);
3040 rmidi->private_data = chip;
3041 strcpy(rmidi->name, "My MIDI");
3042 rmidi->info_flags = SNDRV_RAWMIDI_INFO_OUTPUT |
3046 The first argument is the card pointer, the second argument is the ID
3084 &rmidi->streams[SNDRV_RAWMIDI_STREAM_OUTPUT].substreams,
3086 sprintf(substream->name, "My MIDI Port %d", substream->number + 1);
3091 -----------------
3094 device can be accessed as ``substream->rmidi->private_data``.
3101 int index = substream->number;
3168 before the substream buffer has been emptied, you have to continue
3223 -------
3226 compatibility). ALSA has a nice OPL3 FM control layer, too. The OPL3 API
3229 FM registers can be directly accessed through the direct-FM API, defined
3231 accessed through the Hardware-Dependent Device direct-FM extension API,
3233 OSS direct-FM compatible API in ``/dev/dmfmX`` device.
3249 driver, pass non-zero to the fifth argument (``integrated``). Otherwise,
3263 ``opl3->private_data`` field.
3266 call :c:func:`snd_opl3_init()` to initialize the chip to the
3279 The third argument is the index-offset for the sequencer client assigned
3280 to the OPL3 port. When there is an MPU401-UART, give 1 for here (UART
3283 Hardware-Dependent Devices
3284 --------------------------
3286 Some chips need user-space access for special controls or for loading
3288 (hardware-dependent) device. The hwdep API is defined in
3305 hw->private_data = p;
3306 hw->private_free = mydata_free;
3312 struct mydata *p = hw->private_data;
3318 this chip needs an ioctl::
3320 hw->ops.open = mydata_open;
3321 hw->ops.ioctl = mydata_ioctl;
3322 hw->ops.release = mydata_release;
3327 ---------------
3340 “IEC958 Playback Con Mask” is used to return the bit-mask for the IEC958
3342 returns the bitmask for professional mode. They are read-only controls.
3353 set the raw bit mode. The implementation will depend on the chip, but
3364 ------------
3368 allocation of physically-contiguous pages is done via the
3383 is called “pre-allocation”. As already written, you can call the
3388 &pci->dev, size, max);
3390 where ``size`` is the byte size to be pre-allocated and ``max`` is
3397 (typically identical as ``card->dev``) to the third argument with
3401 bus can be pre-allocated with ``SNDRV_DMA_TYPE_CONTINUOUS`` type.
3409 For the scatter-gather buffers, use ``SNDRV_DMA_TYPE_DEV_SG`` with the
3410 device pointer (see the `Non-Contiguous Buffers`_ section).
3412 Once the buffer is pre-allocated, you can use the allocator in the
3417 Note that you have to pre-allocate to use this function.
3425 &pci->dev, size, max);
3437 -------------------------
3457 Another case is when the chip uses a PCI memory-map region for the
3459 on certain architectures like the Intel one. In non-mmap mode, the data
3467 interleaved or non-interleaved samples. The ``copy`` callback is
3490 offset (``pos``) in the hardware buffer. When coded like memcpy-like
3508 it easier to unify both the interleaved and non-interleaved cases, as
3511 In the case of non-interleaved samples, the implementation will be a bit
3517 the given user-space buffer, but only for the given channel. For
3530 argument. In the case of interleaved samples, the channel argument has
3536 silent-data is 0), and the implementation using a memset-like function
3541 In the case of non-interleaved samples, again, the implementation
3545 Non-Contiguous Buffers
3546 ----------------------
3549 descriptors as in via82xx, you can use scatter-gather (SG) DMA. ALSA
3550 provides an interface for handling SG-buffers. The API is provided in
3553 For creating the SG-buffer handler, call
3557 pre-allocations. You need to pass ``&pci->dev``, where pci is
3558 the struct pci_dev pointer of the chip as well::
3561 &pci->dev, size, max);
3564 ``substream->dma_private`` in turn. You can cast the pointer like::
3566 struct snd_sg_buf *sgbuf = (struct snd_sg_buf *)substream->dma_private;
3568 Then in the :c:func:`snd_pcm_lib_malloc_pages()` call, the common SG-buffer
3569 handler will allocate the non-contiguous kernel pages of the given size
3571 is addressed via runtime->dma_area. The physical address
3572 (``runtime->dma_addr``) is set to zero, because the buffer is
3573 physically non-contiguous. The physical address table is set up in
3574 ``sgbuf->table``. You can get the physical address at a certain offset
3577 If you need to release the SG-buffer data explicitly, call the
3581 ------------------
3598 we don't need to pre-allocate the buffers like other continuous
3612 int err = snd_card_proc_new(card, "my-file", &entry);
3615 created. The above example will create a file ``my-file`` under the
3616 card directory, e.g. ``/proc/asound/card0/my-file``.
3624 proc file for read only. To use this proc file as a read-only text file
3625 as-is, set the read callback with private data via
3628 snd_info_set_text_ops(entry, chip, my_proc_read);
3630 where the second argument (``chip``) is the private data to be used in
3645 struct my_chip *chip = entry->private_data;
3647 snd_iprintf(buffer, "This is my chip!\n");
3648 snd_iprintf(buffer, "Port = %ld\n", chip->port);
3655 entry->mode = S_IFREG | S_IRUGO | S_IWUSR;
3659 entry->c.text.write = my_proc_write;
3666 For a raw-data proc-file, set the attributes as follows::
3672 entry->content = SNDRV_INFO_CONTENT_DATA;
3673 entry->private_data = chip;
3674 entry->c.ops = &my_file_io_ops;
3675 entry->size = 4096;
3676 entry->mode = S_IFREG | S_IRUGO;
3682 You need to use a low-level I/O functions such as
3694 return -EFAULT;
3698 If the size of the info entry has been set up properly, ``count`` and
3706 If the chip is supposed to work with suspend/resume functions, you need
3707 to add power-management code to the driver. The additional code for
3708 power-management should be ifdef-ed with ``CONFIG_PM``, or annotated
3714 possible when the registers of the chip can be safely saved and restored
3750 1. Retrieve the card and the chip data.
3768 struct mychip *chip = card->private_data;
3772 snd_ac97_suspend(chip->ac97);
3774 snd_mychip_save_registers(chip);
3776 snd_mychip_stop_hardware(chip);
3783 1. Retrieve the card and the chip data.
3785 2. Re-initialize the chip.
3802 struct mychip *chip = card->private_data;
3804 snd_mychip_reinit_chip(chip);
3806 snd_mychip_restore_registers(chip);
3808 snd_ac97_resume(chip->ac97);
3810 snd_mychip_restart_chip(chip);
3816 Note that, at the time this callback gets called, the PCM stream has
3821 of the card, make sure that you can get the chip data from the card
3823 chip data individually::
3830 struct mychip *chip;
3833 err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
3836 chip = kzalloc(sizeof(*chip), GFP_KERNEL);
3838 card->private_data = chip;
3842 When you created the chip data with :c:func:`snd_card_new()`, it's
3850 struct mychip *chip;
3853 err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
3856 chip = card->private_data;
3883 have the ``index``, ``id`` and ``enable`` options.
3890 static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;
3903 #define CARD_NAME "My Chip"
3907 module_param_array(id, charp, NULL, 0444);
3908 MODULE_PARM_DESC(id, "ID string for " CARD_NAME " soundcard.");
3916 MODULE_DESCRIPTION("Sound driver for My Chip");
3920 Device-Managed Resources
3926 the (device-)managed resources aka devres or devm family. For
3930 ALSA core provides also the device-managed helper, namely,
3941 so be careful to put the hardware clean-up procedure in
3947 Another thing to be remarked is that you should use device-managed
3957 -------
3964 module name would be snd-xyz. The new driver is usually put into the
3965 alsa-driver tree, ``sound/pci`` directory in the case of PCI
3973 --------------------------------
3979 snd-xyz-y := xyz.o
3980 obj-$(CONFIG_SND_XYZ) += snd-xyz.o
3993 the module will be called snd-xyz.
4009 ---------------------------------
4011 Suppose that the driver snd-xyz have several source files. They are
4017 obj-$(CONFIG_SND) += sound/pci/xyz/
4022 snd-xyz-y := xyz.o abc.o def.o
4023 obj-$(CONFIG_SND_XYZ) += snd-xyz.o
4034 -------------------
4043 ----------------------
4048 return -EINVAL;
4051 ``CONFIG_SND_DEBUG``, is set, if the expression is non-zero, it shows
4061 Kevin Conder reformatted the original plain-text to the DocBook format.