Lines Matching +full:card +full:- +full:detect +full:- +full:delay
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 -------------
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 -------------
171 -------------
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 -----------------
224 /* definition of the chip-specific record */
226 struct snd_card *card;
232 /* chip-specific destructor
240 /* component-destructor
245 return snd_mychip_free(device->device_data);
248 /* chip-specific constructor
251 static int snd_mychip_create(struct snd_card *card,
268 /* allocate a chip-specific data with zero filled */
271 return -ENOMEM;
273 chip->card = card;
280 err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, &ops);
290 /* constructor -- see "Driver Constructor" sub-section */
295 struct snd_card *card;
301 return -ENODEV;
304 return -ENOENT;
308 err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
309 0, &card);
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);
328 err = snd_card_register(card);
333 pci_set_drvdata(pci, card);
338 snd_card_free(card);
342 /* destructor -- see the "Destructor" sub-section */
351 ------------------
354 ``probe`` callback and other component-constructors which are called
368 return -ENODEV;
371 return -ENOENT;
382 2) Create a card instance
387 struct snd_card *card;
390 err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
391 0, &card);
404 err = snd_mychip_create(card, pci, &chip);
416 snd_card_free(card);
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);
434 by alsa-lib's configurator, so keep it simple but unique. Even the
446 `MPU-401 <MIDI (MPU401-UART) Interface_>`__), and other interfaces.
450 6) Register the card instance.
455 err = snd_card_register(card);
467 pci_set_drvdata(pci, card);
471 In the above, the card record is stored. This pointer is used in the
472 remove callback and power-management callbacks, too.
475 ----------
477 The destructor, the remove callback, simply releases the card instance.
489 The above code assumes that the card pointer is set to the PCI driver
493 ------------
511 to include ``<linux/delay.h>`` too.
520 Card Instance
521 -------------
523 For each soundcard, a “card” record must be allocated.
525 A card record is the headquarters of the soundcard. It manages the whole
527 MIDI, synthesizer, and so on. Also, the card record holds the ID and the
528 name strings of the card, manages the root of proc files, and controls
529 the power-management states and hotplug disconnections. The component
530 list on the card record is used to manage the correct release of
533 As mentioned above, to create a card instance, call
536 struct snd_card *card;
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
544 return the card instance. The extra_size argument is used to allocate
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 ----------
554 After the card is created, you can attach the components (devices) to
555 the card instance. In an ALSA driver, a component is represented as a
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
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::
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,
607 sizeof(struct mychip), &card);
615 struct mychip *chip = card->private_data;
618 released together with the card instance.
623 After allocating a card instance via :c:func:`snd_card_new()`
626 struct snd_card *card;
628 err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
629 0, &card);
633 The chip record should have the field to hold the card pointer at least,
638 struct snd_card *card;
643 Then, set the card pointer in the returned chip instance::
645 chip->card = card;
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);
668 registering and disconnecting the card via a setting in snd_device_ops.
669 About registering and disconnecting the card, see the subsections
674 ------------------------
676 After all components are assigned, register the card instance by calling
681 function after releasing the card via :c:func:`snd_card_free()`.
683 For releasing the card instance, you can call simply
695 -----------------
697 In this section, we'll complete the chip-specific constructor,
701 struct snd_card *card;
714 if (chip->irq >= 0)
715 free_irq(chip->irq, chip);
717 pci_release_regions(chip->pci);
719 pci_disable_device(chip->pci);
725 /* chip-specific constructor */
726 static int snd_mychip_create(struct snd_card *card,
747 return -ENXIO;
753 return -ENOMEM;
757 chip->card = card;
758 chip->pci = pci;
759 chip->irq = -1;
768 chip->port = pci_resource_start(pci, 0);
769 if (request_irq(pci->irq, snd_mychip_interrupt,
771 printk(KERN_ERR "cannot grab irq %d\n", pci->irq);
773 return -EBUSY;
775 chip->irq = pci->irq;
776 card->sync_irq = chip->irq;
781 err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, &ops);
826 ------------
847 return -ENXIO;
852 -------------------
863 struct snd_card *card;
873 this number to -1 before actual allocation, since irq 0 is valid. The
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,
898 printk(KERN_ERR "cannot grab irq %d\n", pci->irq);
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
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::
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
1004 chip->iobase_phys = pci_resource_start(pci, 0);
1005 chip->iobase_virt = ioremap(chip->iobase_phys,
1013 if (chip->iobase_virt)
1014 iounmap(chip->iobase_virt);
1016 pci_release_regions(chip->pci);
1028 chip->iobase_virt = pci_iomap(pci, 0, 0);
1034 -----------
1059 all-zero entry.
1099 -------
1102 for each driver to implement the low-level functions to access its
1109 Each card device can have up to four PCM instances. A PCM instance
1126 -----------------
1176 struct snd_pcm_runtime *runtime = substream->runtime;
1178 runtime->hw = snd_mychip_playback_hw;
1179 /* more hardware-initialization will be done here */
1188 /* the hardware-specific codes will be here */
1198 struct snd_pcm_runtime *runtime = substream->runtime;
1200 runtime->hw = snd_mychip_capture_hw;
1201 /* more hardware-initialization will be done here */
1210 /* the hardware-specific codes will be here */
1219 /* the hardware-specific codes will be here */
1227 /* the hardware-specific codes will be here */
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;
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 ---------------
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;
1354 first argument is the card pointer to which this PCM is assigned, and
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``::
1434 kfree(chip->my_private_pcm_data);
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 */
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
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
1633 pass the ``CONTINUOUS`` bit additionally. The pre-defined rate bits
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
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``
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
1994 If the IRQ handler is released by the card destructor, you don't need
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 ---------------------
2106 spin_lock(&chip->lock);
2110 spin_unlock(&chip->lock);
2111 snd_pcm_period_elapsed(chip->substream);
2112 spin_lock(&chip->lock);
2116 spin_unlock(&chip->lock);
2120 Also, when the device can detect a buffer underrun/overrun, the driver
2144 spin_lock(&chip->lock);
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);
2189 ---------
2193 usually avoided via spin-locks, mutexes or semaphores. In general, if a
2201 example, the ``hw_params`` callback is non-atomic, while the ``trigger``
2210 callbacks (e.g. ``trigger`` callback). To implement some delay in such a
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 ----------------------
2384 ``SNDRV_CTL_ELEM_IFACE_XXX``, which is usually ``MIXER``. Use ``CARD``
2387 card, use ``HWDEP``, ``PCM``, ``RAWMIDI``, ``TIMER``, or ``SEQUENCER``,
2393 its name. There are pre-defined standard control names. The details
2399 codecs exist on the card. If the index is zero, you can omit the
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),
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.
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;
2615 This callback is used to write a value coming from user-space.
2624 if (chip->current_value !=
2625 ucontrol->value.integer.value[0]) {
2627 ucontrol->value.integer.value[0]);
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
2666 card.
2669 -------------------
2674 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE, id_pointer);
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
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;
2767 err = snd_ac97_bus(chip->card, 0, &ops, NULL, &bus);
2772 return snd_ac97_mixer(bus, &ac97, &chip->ac97);
2777 ----------------
2788 snd_ac97_bus(card, 0, &ops, NULL, &pbus);
2800 snd_ac97_mixer(bus, &ac97, &chip->ac97);
2802 where chip->ac97 is a pointer to a newly created ``ac97_t``
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.
2852 --------------------------------
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 ---------------
2911 When there are several codecs on the same card, you need to call
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
2934 ----------------
2939 snd_mpu401_uart_new(card, 0, MPU401_HW_MPU401, port, info_flags,
2943 The first argument is the card pointer, and the second is the index of
2949 The 4th argument is the I/O port address. Many backward-compatible
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
2973 devices on the card, set ``MPU401_INFO_IRQ_HOOK`` (see
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 ----------------------
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;
3223 -------
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.
3239 snd_opl3_create(card, lport, rport, OPL3_HW_OPL3_XXX,
3242 The first argument is the card pointer, the second one is the left port
3248 When the left and right ports have been already allocated by the card
3249 driver, pass non-zero to the fifth argument (``integrated``). Otherwise,
3257 snd_opl3_new(card, OPL3_HW_OPL3_XXX, &opl3);
3263 ``opl3->private_data`` field.
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
3296 snd_hwdep_new(card, "My HWDEP", 0, &hw);
3305 hw->private_data = p;
3306 hw->private_free = mydata_free;
3312 struct mydata *p = hw->private_data;
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.
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
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
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``.
3620 automatically in the card registration and release functions.
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
3645 struct my_chip *chip = entry->private_data;
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;
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
3750 1. Retrieve the card and the chip data.
3767 struct snd_card *card = dev_get_drvdata(dev);
3768 struct mychip *chip = card->private_data;
3770 snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);
3772 snd_ac97_suspend(chip->ac97);
3783 1. Retrieve the card and the chip data.
3785 2. Re-initialize the chip.
3801 struct snd_card *card = dev_get_drvdata(dev);
3802 struct mychip *chip = card->private_data;
3808 snd_ac97_resume(chip->ac97);
3812 snd_power_change_state(card, SNDRV_CTL_POWER_D0);
3821 of the card, make sure that you can get the chip data from the card
3829 struct snd_card *card;
3833 err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
3834 0, &card);
3838 card->private_data = chip;
3849 struct snd_card *card;
3853 err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
3854 sizeof(struct mychip), &card);
3856 chip = card->private_data;
3893 If the module supports only a single card, they could be single
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,
3931 :c:func:`snd_devm_card_new()` for creating a card object.
3940 Also, the ``private_free`` callback is always called at the card free,
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
3949 the card in that way. Mixing up with the normal and the managed
3957 -------
3963 Suppose that you create a new PCI driver for the card “xyz”. The card
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.