Commit 1b437d2f authored by Takashi Iwai's avatar Takashi Iwai Committed by Greg Kroah-Hartman
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usb: gadget: midi2: Add "Operation Mode" control 



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: default avatarTakashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20230725062206.9674-7-tiwai@suse.de


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 8559caa9

Documentation/usb/gadget-testing.rst

+11 −0
Original line number Diff line number Diff line
@@ -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.

drivers/usb/gadget/function/f_midi2.c

+35 −0
Original line number Diff line number Diff line
@@ -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;