ALSA: firewire-motu: notify event for parameter change in register DSP model

This commit copies queued event for change of register DSP into
userspace when application operates ALSA hwdep character device.
The notification occurs only when packet streaming is running.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20211015080826.34847-12-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>

3 files changed, 78 insertions, 9 deletions

diff --git a/sound/firewire/motu/motu-hwdep.c b/sound/firewire/motu/motu-hwdep.c
index 389e59ff768b..9c2e457ce692 100644
--- a/sound/firewire/motu/motu-hwdep.c
+++ b/sound/firewire/motu/motu-hwdep.c
@@ -25,7 +25,8 @@ static long hwdep_read(struct snd_hwdep *hwdep, char __user *buf, long count,
 
 	spin_lock_irq(&motu->lock);
 
-	while (!motu->dev_lock_changed && motu->msg == 0) {
+	while (!motu->dev_lock_changed && motu->msg == 0 &&
+			snd_motu_register_dsp_message_parser_count_event(motu) == 0) {
 		prepare_to_wait(&motu->hwdep_wait, &wait, TASK_INTERRUPTIBLE);
 		spin_unlock_irq(&motu->lock);
 		schedule();
@@ -40,20 +41,46 @@ static long hwdep_read(struct snd_hwdep *hwdep, char __user *buf, long count,
 		event.lock_status.type = SNDRV_FIREWIRE_EVENT_LOCK_STATUS;
 		event.lock_status.status = (motu->dev_lock_count > 0);
 		motu->dev_lock_changed = false;
+		spin_unlock_irq(&motu->lock);
 
-		count = min_t(long, count, sizeof(event.lock_status));
-	} else {
+		count = min_t(long, count, sizeof(event));
+		if (copy_to_user(buf, &event, count))
+			return -EFAULT;
+	} else if (motu->msg > 0) {
 		event.motu_notification.type = SNDRV_FIREWIRE_EVENT_MOTU_NOTIFICATION;
 		event.motu_notification.message = motu->msg;
 		motu->msg = 0;
+		spin_unlock_irq(&motu->lock);
 
-		count = min_t(long, count, sizeof(event.motu_notification));
-	}
+		count = min_t(long, count, sizeof(event));
+		if (copy_to_user(buf, &event, count))
+			return -EFAULT;
+	} else if (snd_motu_register_dsp_message_parser_count_event(motu) > 0) {
+		size_t consumed = 0;
+		u32 __user *ptr;
+		u32 ev;
 
-	spin_unlock_irq(&motu->lock);
+		spin_unlock_irq(&motu->lock);
 
-	if (copy_to_user(buf, &event, count))
-		return -EFAULT;
+		// Header is filled later.
+		consumed += sizeof(event.motu_register_dsp_change);
+
+		while (consumed < count &&
+		       snd_motu_register_dsp_message_parser_copy_event(motu, &ev)) {
+			ptr = (u32 __user *)(buf + consumed);
+			if (put_user(ev, ptr))
+				return -EFAULT;
+			consumed += sizeof(ev);
+		}
+
+		event.motu_register_dsp_change.type = SNDRV_FIREWIRE_EVENT_MOTU_REGISTER_DSP_CHANGE;
+		event.motu_register_dsp_change.count =
+			(consumed - sizeof(event.motu_register_dsp_change)) / 4;
+		if (copy_to_user(buf, &event, sizeof(event.motu_register_dsp_change)))
+			return -EFAULT;
+
+		count = consumed;
+	}
 
 	return count;
 }
@@ -67,7 +94,8 @@ static __poll_t hwdep_poll(struct snd_hwdep *hwdep, struct file *file,
 	poll_wait(file, &motu->hwdep_wait, wait);
 
 	spin_lock_irq(&motu->lock);
-	if (motu->dev_lock_changed || motu->msg)
+	if (motu->dev_lock_changed || motu->msg ||
+	    snd_motu_register_dsp_message_parser_count_event(motu) > 0)
 		events = EPOLLIN | EPOLLRDNORM;
 	else
 		events = 0;
diff --git a/sound/firewire/motu/motu-register-dsp-message-parser.c b/sound/firewire/motu/motu-register-dsp-message-parser.c
index cda8e6d987cc..cbc06b3b70f6 100644
--- a/sound/firewire/motu/motu-register-dsp-message-parser.c
+++ b/sound/firewire/motu/motu-register-dsp-message-parser.c
@@ -95,6 +95,7 @@ struct msg_parser {
 
 	u32 event_queue[EVENT_QUEUE_SIZE];
 	unsigned int push_pos;
+	unsigned int pull_pos;
 };
 
 int snd_motu_register_dsp_message_parser_new(struct snd_motu *motu)
@@ -122,6 +123,7 @@ int snd_motu_register_dsp_message_parser_init(struct snd_motu *motu)
 	return 0;
 }
 
+// Rough implementaion of queue without overrun check.
 static void queue_event(struct snd_motu *motu, u8 msg_type, u8 identifier0, u8 identifier1, u8 val)
 {
 	struct msg_parser *parser = motu->message_parser;
@@ -145,6 +147,7 @@ void snd_motu_register_dsp_message_parser_parse(struct snd_motu *motu, const str
 {
 	struct msg_parser *parser = motu->message_parser;
 	bool meter_pos_quirk = parser->meter_pos_quirk;
+	unsigned int pos = parser->push_pos;
 	unsigned long flags;
 	int i;
 
@@ -351,6 +354,9 @@ void snd_motu_register_dsp_message_parser_parse(struct snd_motu *motu, const str
 		}
 	}
 
+	if (pos != parser->push_pos)
+		wake_up(&motu->hwdep_wait);
+
 	spin_unlock_irqrestore(&parser->lock, flags);
 }
 
@@ -375,3 +381,36 @@ void snd_motu_register_dsp_message_parser_copy_parameter(struct snd_motu *motu,
 	memcpy(param, &parser->param, sizeof(*param));
 	spin_unlock_irqrestore(&parser->lock, flags);
 }
+
+unsigned int snd_motu_register_dsp_message_parser_count_event(struct snd_motu *motu)
+{
+	struct msg_parser *parser = motu->message_parser;
+
+	if (parser->pull_pos > parser->push_pos)
+		return EVENT_QUEUE_SIZE - parser->pull_pos + parser->push_pos;
+	else
+		return parser->push_pos - parser->pull_pos;
+}
+
+bool snd_motu_register_dsp_message_parser_copy_event(struct snd_motu *motu, u32 *event)
+{
+	struct msg_parser *parser = motu->message_parser;
+	unsigned int pos = parser->pull_pos;
+	unsigned long flags;
+
+	if (pos == parser->push_pos)
+		return false;
+
+	spin_lock_irqsave(&parser->lock, flags);
+
+	*event = parser->event_queue[pos];
+
+	++pos;
+	if (pos >= EVENT_QUEUE_SIZE)
+		pos = 0;
+	parser->pull_pos = pos;
+
+	spin_unlock_irqrestore(&parser->lock, flags);
+
+	return true;
+}
diff --git a/sound/firewire/motu/motu.h b/sound/firewire/motu/motu.h
index 9703d3af59ec..79704ae6a73e 100644
--- a/sound/firewire/motu/motu.h
+++ b/sound/firewire/motu/motu.h
@@ -283,6 +283,8 @@ void snd_motu_register_dsp_message_parser_copy_meter(struct snd_motu *motu,
 					struct snd_firewire_motu_register_dsp_meter *meter);
 void snd_motu_register_dsp_message_parser_copy_parameter(struct snd_motu *motu,
 					struct snd_firewire_motu_register_dsp_parameter *params);
+unsigned int snd_motu_register_dsp_message_parser_count_event(struct snd_motu *motu);
+bool snd_motu_register_dsp_message_parser_copy_event(struct snd_motu *motu, u32 *event);
 
 int snd_motu_command_dsp_message_parser_new(struct snd_motu *motu);
 int snd_motu_command_dsp_message_parser_init(struct snd_motu *motu, enum cip_sfc sfc);