ALSA: seq: Introduce SNDRV_SEQ_IOCTL_USER_PVERSION ioctl

For the future extension of ALSA sequencer ABI, introduce a new ioctl
SNDRV_SEQ_IOCTL_USER_PVERSION.  This is similar like the ioctls used
in PCM and other interfaces, for an application to specify its
supporting ABI version.

The use of this ioctl will be mandatory for the upcoming UMP support.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20230523075358.9672-25-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Author: tiwai

include/uapi/sound/asequencer.h

@@ -561,6 +561,7 @@ struct snd_seq_query_subs {
 #define SNDRV_SEQ_IOCTL_CLIENT_ID	_IOR ('S', 0x01, int)
 #define SNDRV_SEQ_IOCTL_SYSTEM_INFO	_IOWR('S', 0x02, struct snd_seq_system_info)
 #define SNDRV_SEQ_IOCTL_RUNNING_MODE	_IOWR('S', 0x03, struct snd_seq_running_info)
+#define SNDRV_SEQ_IOCTL_USER_PVERSION	_IOW('S', 0x04, int)
 
 #define SNDRV_SEQ_IOCTL_GET_CLIENT_INFO	_IOWR('S', 0x10, struct snd_seq_client_info)
 #define SNDRV_SEQ_IOCTL_SET_CLIENT_INFO	_IOW ('S', 0x11, struct snd_seq_client_info)

sound/core/seq/seq_clientmgr.c

@@ -1056,6 +1056,12 @@ static int snd_seq_ioctl_pversion(struct snd_seq_client *client, void *arg)
 	return 0;
 }
 
+static int snd_seq_ioctl_user_pversion(struct snd_seq_client *client, void *arg)
+{
+	client->user_pversion = *(unsigned int *)arg;
+	return 0;
+}
+
 static int snd_seq_ioctl_client_id(struct snd_seq_client *client, void *arg)
 {
 	int *client_id = arg;
@@ -1985,6 +1991,7 @@ static const struct ioctl_handler {
 	int (*func)(struct snd_seq_client *client, void *arg);
 } ioctl_handlers[] = {
 	{ SNDRV_SEQ_IOCTL_PVERSION, snd_seq_ioctl_pversion },
+	{ SNDRV_SEQ_IOCTL_USER_PVERSION, snd_seq_ioctl_user_pversion },
 	{ SNDRV_SEQ_IOCTL_CLIENT_ID, snd_seq_ioctl_client_id },
 	{ SNDRV_SEQ_IOCTL_SYSTEM_INFO, snd_seq_ioctl_system_info },
 	{ SNDRV_SEQ_IOCTL_RUNNING_MODE, snd_seq_ioctl_running_mode },
@@ -2125,6 +2132,7 @@ int snd_seq_create_kernel_client(struct snd_card *card, int client_index,
 	client->accept_input = 1;
 	client->accept_output = 1;
 	client->data.kernel.card = card;
+	client->user_pversion = SNDRV_SEQ_VERSION;
 
 	va_start(args, name_fmt);
 	vsnprintf(client->name, sizeof(client->name), name_fmt, args);

sound/core/seq/seq_clientmgr.h

@@ -35,6 +35,7 @@ struct snd_seq_client {
 	snd_seq_client_type_t type;
 	unsigned int accept_input: 1,
 		accept_output: 1;
+	unsigned int user_pversion;
 	char name[64];		/* client name */
 	int number;		/* client number */
 	unsigned int filter;	/* filter flags */

sound/core/seq/seq_compat.c

@@ -81,6 +81,7 @@ static long snd_seq_ioctl_compat(struct file *file, unsigned int cmd, unsigned l
 
 	switch (cmd) {
 	case SNDRV_SEQ_IOCTL_PVERSION:
+	case SNDRV_SEQ_IOCTL_USER_PVERSION:
 	case SNDRV_SEQ_IOCTL_CLIENT_ID:
 	case SNDRV_SEQ_IOCTL_SYSTEM_INFO:
 	case SNDRV_SEQ_IOCTL_GET_CLIENT_INFO: