Commit a7980768 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: ump: Add helper to change MIDI protocol 

This is a preliminary patch for MIDI 2.0 USB gadget driver.
Export a new helper to allow changing the current MIDI protocol from
the outside.

Link: https://lore.kernel.org/r/20230621110241.4751-2-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent febdfa0e

include/sound/ump.h

+2 −0
Original line number Diff line number Diff line
@@ -108,6 +108,8 @@ static inline int snd_ump_attach_legacy_rawmidi(struct snd_ump_endpoint *ump, 
}

#endif



int snd_ump_switch_protocol(struct snd_ump_endpoint *ump, unsigned int protocol);



/*

 * Some definitions for UMP

 */

sound/core/ump.c

+24 −7
Original line number Diff line number Diff line
@@ -671,18 +671,35 @@ static void seq_notify_protocol(struct snd_ump_endpoint *ump) 
#endif /* CONFIG_SND_SEQUENCER */

}



/**

 * snd_ump_switch_protocol - switch MIDI protocol

 * @ump: UMP endpoint

 * @protocol: protocol to switch to

 *

 * Returns 1 if the protocol is actually switched, 0 if unchanged

 */

int snd_ump_switch_protocol(struct snd_ump_endpoint *ump, unsigned int protocol)

{

	protocol &= ump->info.protocol_caps;

	if (protocol == ump->info.protocol)

		return 0;



	ump->info.protocol = protocol;

	ump_dbg(ump, "New protocol = %x (caps = %x)\n",

		protocol, ump->info.protocol_caps);

	seq_notify_protocol(ump);

	return 1;

}

EXPORT_SYMBOL_GPL(snd_ump_switch_protocol);



/* handle EP stream config message; update the UMP protocol */

static int ump_handle_stream_cfg_msg(struct snd_ump_endpoint *ump,

				     const union snd_ump_stream_msg *buf)

{

	unsigned int old_protocol = ump->info.protocol;



	ump->info.protocol =

	unsigned int protocol =

		(buf->stream_cfg.protocol << 8) | buf->stream_cfg.jrts;

	ump_dbg(ump, "Current protocol = %x (caps = %x)\n",

		ump->info.protocol, ump->info.protocol_caps);

	if (ump->parsed && ump->info.protocol != old_protocol)

		seq_notify_protocol(ump);



	snd_ump_switch_protocol(ump, protocol);

	return 1; /* finished */

}