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usb: gadget: midi2: Add "Operation Mode" control

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Add a new ALSA control element to watch the current operation mode
(MIDI 1.0 or MIDI 2.0).  It's a read-only control that reflects the
current value of altsetting, and 0 means unused, 1 for MIDI 1.0
(altset 0) and 2 for MIDI 2.0 (altset 1).

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20230725062206.9674-7-tiwai@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Takashi Iwai 2023-07-25 08:22:05 +02:00 committed by Greg Kroah-Hartman
parent 8559caa985
commit 1b437d2fb3
2 changed files with 46 additions and 0 deletions
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11
Documentation/usb/gadget-testing.rst
View File

@ -1106,3 +1106,14 @@ On the host::
The access to MIDI 1.0 on altset 0 on the host is supported, and it's
translated from/to UMP packets on the gadget. It's bound to only
Function Block 0.
The current operation mode can be observed in ALSA control element
"Operation Mode" for SND_CTL_IFACE_RAWMIDI. For example::
$ amixer -c1 contents
numid=1,iface=RAWMIDI,name='Operation Mode'
; type=INTEGER,access=r--v----,values=1,min=0,max=2,step=0
: values=2
where 0 = unused, 1 = MIDI 1.0 (altset 0), 2 = MIDI 2.0 (altset 1).
The example above shows it's running in 2, i.e. MIDI 2.0.

35
drivers/usb/gadget/function/f_midi2.c
View File

@ -9,6 +9,7 @@
#include <linux/slab.h>
#include <sound/core.h>
#include <sound/control.h>
#include <sound/ump.h>
#include <sound/ump_msg.h>
#include <sound/ump_convert.h>
@ -1450,6 +1451,36 @@ static const struct snd_ump_ops f_midi2_ump_ops = {
.drain = f_midi2_ump_drain,
};
/*
* "Operation Mode" control element
*/
static int f_midi2_operation_mode_info(struct snd_kcontrol *kcontrol,
struct snd_ctl_elem_info *uinfo)
{
uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
uinfo->count = 1;
uinfo->value.integer.min = MIDI_OP_MODE_UNSET;
uinfo->value.integer.max = MIDI_OP_MODE_MIDI2;
return 0;
}
static int f_midi2_operation_mode_get(struct snd_kcontrol *kcontrol,
struct snd_ctl_elem_value *ucontrol)
{
struct f_midi2 *midi2 = snd_kcontrol_chip(kcontrol);
ucontrol->value.integer.value[0] = midi2->operation_mode;
return 0;
}
static const struct snd_kcontrol_new operation_mode_ctl = {
.iface = SNDRV_CTL_ELEM_IFACE_RAWMIDI,
.name = "Operation Mode",
.access = SNDRV_CTL_ELEM_ACCESS_READ | SNDRV_CTL_ELEM_ACCESS_VOLATILE,
.info = f_midi2_operation_mode_info,
.get = f_midi2_operation_mode_get,
};
/*
* ALSA UMP instance creation / deletion
*/
@ -1547,6 +1578,10 @@ static int f_midi2_create_card(struct f_midi2 *midi2)
id++;
}
err = snd_ctl_add(card, snd_ctl_new1(&operation_mode_ctl, midi2));
if (err < 0)
goto error;
err = snd_card_register(card);
if (err < 0)
goto error;