X-Git-Url: https://git.karo-electronics.de/?a=blobdiff_plain;f=Documentation%2Fsound%2Falsa%2FDocBook%2Fwriting-an-alsa-driver.tmpl;h=2c3fc3cb3b6bdced5bf553b223719f8b370a6c26;hb=d1761d1b14158498d4782d555a9b367ea4647224;hp=ccd0a953953dcc09a52288d766bff968afff3e4b;hpb=88d5a7bb75b5e8f600e79b16abaf008c7fdfd27d;p=mv-sheeva.git
diff --git a/Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl b/Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl
index ccd0a953953..2c3fc3cb3b6 100644
--- a/Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl
+++ b/Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl
@@ -18,8 +18,8 @@
- November 17, 2005
- 0.3.6
+ September 10, 2007
+ 0.3.7
@@ -405,8 +405,9 @@
/* definition of the chip-specific record */
struct mychip {
struct snd_card *card;
- // rest of implementation will be in the section
- // "PCI Resource Managements"
+ /* rest of implementation will be in the section
+ * "PCI Resource Managements"
+ */
};
/* chip-specific destructor
@@ -414,7 +415,7 @@
*/
static int snd_mychip_free(struct mychip *chip)
{
- .... // will be implemented later...
+ .... /* will be implemented later... */
}
/* component-destructor
@@ -440,8 +441,9 @@
*rchip = NULL;
- // check PCI availability here
- // (see "PCI Resource Managements")
+ /* check PCI availability here
+ * (see "PCI Resource Managements")
+ */
....
/* allocate a chip-specific data with zero filled */
@@ -451,12 +453,13 @@
chip->card = card;
- // rest of initialization here; will be implemented
- // later, see "PCI Resource Managements"
+ /* rest of initialization here; will be implemented
+ * later, see "PCI Resource Managements"
+ */
....
- if ((err = snd_device_new(card, SNDRV_DEV_LOWLEVEL,
- chip, &ops)) < 0) {
+ err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, &ops);
+ if (err < 0) {
snd_mychip_free(chip);
return err;
}
@@ -490,7 +493,8 @@
return -ENOMEM;
/* (3) */
- if ((err = snd_mychip_create(card, pci, &chip)) < 0) {
+ err = snd_mychip_create(card, pci, &chip);
+ if (err < 0) {
snd_card_free(card);
return err;
}
@@ -502,10 +506,11 @@
card->shortname, chip->ioport, chip->irq);
/* (5) */
- .... // implemented later
+ .... /* implemented later */
/* (6) */
- if ((err = snd_card_register(card)) < 0) {
+ err = snd_card_register(card);
+ if (err < 0) {
snd_card_free(card);
return err;
}
@@ -605,7 +610,8 @@
irq >= 0)
@@ -1119,7 +1126,8 @@
*rchip = NULL;
/* initialize the PCI entry */
- if ((err = pci_enable_device(pci)) < 0)
+ err = pci_enable_device(pci);
+ if (err < 0)
return err;
/* check PCI availability (28bit DMA) */
if (pci_set_dma_mask(pci, DMA_28BIT_MASK) < 0 ||
@@ -1141,7 +1149,8 @@
chip->irq = -1;
/* (1) PCI resource allocation */
- if ((err = pci_request_regions(pci, "My Chip")) < 0) {
+ err = pci_request_regions(pci, "My Chip");
+ if (err < 0) {
kfree(chip);
pci_disable_device(pci);
return err;
@@ -1156,10 +1165,10 @@
chip->irq = pci->irq;
/* (2) initialization of the chip hardware */
- .... // (not implemented in this document)
+ .... /* (not implemented in this document) */
- if ((err = snd_device_new(card, SNDRV_DEV_LOWLEVEL,
- chip, &ops)) < 0) {
+ err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, &ops);
+ if (err < 0) {
snd_mychip_free(chip);
return err;
}
@@ -1233,7 +1242,8 @@
irq, snd_mychip_interrupt,
- IRQF_DISABLED|IRQF_SHARED, "My Chip", chip)) {
+ IRQF_SHARED, "My Chip", chip)) {
printk(KERN_ERR "cannot grab irq %d\n", pci->irq);
snd_mychip_free(chip);
return -EBUSY;
@@ -1360,8 +1371,7 @@
runtime;
runtime->hw = snd_mychip_playback_hw;
- // more hardware-initialization will be done here
+ /* more hardware-initialization will be done here */
+ ....
return 0;
}
@@ -1782,7 +1793,8 @@
static int snd_mychip_playback_close(struct snd_pcm_substream *substream)
{
struct mychip *chip = snd_pcm_substream_chip(substream);
- // the hardware-specific codes will be here
+ /* the hardware-specific codes will be here */
+ ....
return 0;
}
@@ -1794,7 +1806,8 @@
struct snd_pcm_runtime *runtime = substream->runtime;
runtime->hw = snd_mychip_capture_hw;
- // more hardware-initialization will be done here
+ /* more hardware-initialization will be done here */
+ ....
return 0;
}
@@ -1802,7 +1815,8 @@
static int snd_mychip_capture_close(struct snd_pcm_substream *substream)
{
struct mychip *chip = snd_pcm_substream_chip(substream);
- // the hardware-specific codes will be here
+ /* the hardware-specific codes will be here */
+ ....
return 0;
}
@@ -1845,10 +1859,12 @@
{
switch (cmd) {
case SNDRV_PCM_TRIGGER_START:
- // do something to start the PCM engine
+ /* do something to start the PCM engine */
+ ....
break;
case SNDRV_PCM_TRIGGER_STOP:
- // do something to stop the PCM engine
+ /* do something to stop the PCM engine */
+ ....
break;
default:
return -EINVAL;
@@ -1901,8 +1917,8 @@
struct snd_pcm *pcm;
int err;
- if ((err = snd_pcm_new(chip->card, "My Chip", 0, 1, 1,
- &pcm)) < 0)
+ err = snd_pcm_new(chip->card, "My Chip", 0, 1, 1, &pcm);
+ if (err < 0)
return err;
pcm->private_data = chip;
strcpy(pcm->name, "My Chip");
@@ -1940,8 +1956,8 @@
struct snd_pcm *pcm;
int err;
- if ((err = snd_pcm_new(chip->card, "My Chip", 0, 1, 1,
- &pcm)) < 0)
+ err = snd_pcm_new(chip->card, "My Chip", 0, 1, 1, &pcm);
+ if (err < 0)
return err;
pcm->private_data = chip;
strcpy(pcm->name, "My Chip");
@@ -2098,7 +2114,7 @@
struct mychip *chip = snd_pcm_chip(pcm);
/* free your own data */
kfree(chip->my_private_pcm_data);
- // do what you like else
+ /* do what you like else */
....
}
@@ -2127,7 +2143,7 @@
accessible via substream->runtime.
This runtime pointer holds the various information; it holds
the copy of hw_params and sw_params configurations, the buffer
- pointers, mmap records, spinlocks, etc. Almost everyhing you
+ pointers, mmap records, spinlocks, etc. Almost everything you
need for controlling the PCM can be found there.
@@ -2340,7 +2356,7 @@ struct _snd_pcm_runtime {
When the PCM substreams can be synchronized (typically,
- synchorinized start/stop of a playback and a capture streams),
+ synchronized start/stop of a playback and a capture streams),
you can give SNDRV_PCM_INFO_SYNC_START,
too. In this case, you'll need to check the linked-list of
PCM substreams in the trigger callback. This will be
@@ -2885,10 +2901,10 @@ struct _snd_pcm_runtime {
Interrupt Handler Case #1
lock);
@@ -3073,7 +3088,7 @@ struct _snd_pcm_runtime {
spin_unlock(&chip->lock);
snd_pcm_period_elapsed(chip->substream);
spin_lock(&chip->lock);
- // acknowledge the interrupt if necessary
+ /* acknowledge the interrupt if necessary */
}
....
spin_unlock(&chip->lock);
@@ -3106,8 +3121,7 @@ struct _snd_pcm_runtime {
Interrupt Handler Case #2
lock);
@@ -3137,7 +3151,7 @@ struct _snd_pcm_runtime {
snd_pcm_period_elapsed(substream);
spin_lock(&chip->lock);
}
- // acknowledge the interrupt if necessary
+ /* acknowledge the interrupt if necessary */
}
....
spin_unlock(&chip->lock);
@@ -3247,7 +3261,7 @@ struct _snd_pcm_runtime {
You can even define your own constraint rules.
For example, let's suppose my_chip can manage a substream of 1 channel
if and only if the format is S16_LE, otherwise it supports any format
- specified in the snd_pcm_hardware stucture (or in any
+ specified in the snd_pcm_hardware structure (or in any
other constraint_list). You can build a rule like this:
@@ -3458,6 +3472,13 @@ struct _snd_pcm_runtime {
(casted to unsigned long) of some record to this field, too.
+
+ The tlv field can be used to provide
+ metadata about the control; see the
+
+ Metadata subsection.
+
+
The other three are
@@ -3607,7 +3628,7 @@ struct _snd_pcm_runtime {
Example of info callback
type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
@@ -3642,7 +3663,7 @@ struct _snd_pcm_runtime {
+
+
+ Some common info callbacks are prepared for easy use:
+ snd_ctl_boolean_mono_info() and
+ snd_ctl_boolean_stereo_info().
+ Obviously, the former is an info callback for a mono channel
+ boolean item, just like snd_myctl_mono_info
+ above, and the latter is for a stereo channel boolean item.
+
+
@@ -3690,16 +3721,6 @@ struct _snd_pcm_runtime {
-
- Here, the chip instance is retrieved via
- snd_kcontrol_chip() macro. This macro
- just accesses to kcontrol->private_data. The
- kcontrol->private_data field is
- given as the argument of snd_ctl_new()
- (see the later subsection
- Constructor).
-
-
The value field is depending on
the type of control as well as on info callback. For example,
@@ -3780,7 +3801,7 @@ struct _snd_pcm_runtime {
Like get callback,
when the control has more than one elements,
- all elemehts must be evaluated in this callback, too.
+ all elements must be evaluated in this callback, too.
@@ -3807,7 +3828,8 @@ struct _snd_pcm_runtime {
@@ -3856,6 +3878,56 @@ struct _snd_pcm_runtime {
+
+ Metadata
+
+ To provide information about the dB values of a mixer control, use
+ on of the DECLARE_TLV_xxx macros from
+ <sound/tlv.h> to define a variable
+ containing this information, set thetlv.p
+ field to point to this variable, and include the
+ SNDRV_CTL_ELEM_ACCESS_TLV_READ flag in the
+ access field; like this:
+
+
+
+
+
+
+
+
+ The DECLARE_TLV_DB_SCALE macro defines
+ information about a mixer control where each step in the control's
+ value changes the dB value by a constant dB amount.
+ The first parameter is the name of the variable to be defined.
+ The second parameter is the minimum value, in units of 0.01 dB.
+ The third parameter is the step size, in units of 0.01 dB.
+ Set the fourth parameter to 1 if the minimum value actually mutes
+ the control.
+
+
+
+ The DECLARE_TLV_DB_LINEAR macro defines
+ information about a mixer control where the control's value affects
+ the output linearly.
+ The first parameter is the name of the variable to be defined.
+ The second parameter is the minimum value, in units of 0.01 dB.
+ The third parameter is the maximum value, in units of 0.01 dB.
+ If the minimum value mutes the control, set the second parameter to
+ TLV_DB_GAIN_MUTE.
+
+
+
@@ -3893,7 +3965,7 @@ struct _snd_pcm_runtime {
{
struct mychip *chip = ac97->private_data;
....
- // read a register value here from the codec
+ /* read a register value here from the codec */
return the_register_value;
}
@@ -3902,7 +3974,7 @@ struct _snd_pcm_runtime {
{
struct mychip *chip = ac97->private_data;
....
- // write the given register value to the codec
+ /* write the given register value to the codec */
}
static int snd_mychip_ac97(struct mychip *chip)
@@ -3915,7 +3987,8 @@ struct _snd_pcm_runtime {
.read = snd_mychip_ac97_read,
};
- if ((err = snd_ac97_bus(chip->card, 0, &ops, NULL, &bus)) < 0)
+ err = snd_ac97_bus(chip->card, 0, &ops, NULL, &bus);
+ if (err < 0)
return err;
memset(&ac97, 0, sizeof(ac97));
ac97.private_data = chip;
@@ -4460,10 +4533,10 @@ struct _snd_pcm_runtime {
streams[SNDRV_RAWMIDI_STREAM_OUTPUT].substreams) {
- substream = list_entry(list, struct snd_rawmidi_substream, list);
+ list_for_each_entry(substream,
+ &rmidi->streams[SNDRV_RAWMIDI_STREAM_OUTPUT].substreams,
+ list {
sprintf(substream->name, "My MIDI Port %d", substream->number + 1);
}
/* same for SNDRV_RAWMIDI_STREAM_INPUT */
@@ -5541,12 +5614,12 @@ struct _snd_pcm_runtime {
#ifdef CONFIG_PM
static int snd_my_suspend(struct pci_dev *pci, pm_message_t state)
{
- .... /* do things for suspsend */
+ .... /* do things for suspend */
return 0;
}
static int snd_my_resume(struct pci_dev *pci)
{
- .... /* do things for suspsend */
+ .... /* do things for suspend */
return 0;
}
#endif
@@ -6111,7 +6184,7 @@ struct _snd_pcm_runtime {
-
+ Acknowledgments
I would like to thank Phil Kerr for his help for improvement and