ALSA: firewire-motu: add ioctl command to read cached parameters in register DSP model

This patch adds new ioctl command for userspace applications to read
cached parameters of register DSP.

The structured data includes model-dependent parameters. Userspace
application should be carefully programmed so that what parameter is
common and specific.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20211015080826.34847-10-o-takashi@sakamocchi.jpSigned-off-by: Takashi Iwai <tiwai@suse.de>

include/uapi/sound/firewire.h

@@ -82,6 +82,7 @@ union snd_firewire_event {
 #define SNDRV_FIREWIRE_IOCTL_TASCAM_STATE _IOR('H', 0xfb, struct snd_firewire_tascam_state)
 #define SNDRV_FIREWIRE_IOCTL_MOTU_REGISTER_DSP_METER	_IOR('H', 0xfc, struct snd_firewire_motu_register_dsp_meter)
 #define SNDRV_FIREWIRE_IOCTL_MOTU_COMMAND_DSP_METER	_IOR('H', 0xfd, struct snd_firewire_motu_command_dsp_meter)
+#define SNDRV_FIREWIRE_IOCTL_MOTU_REGISTER_DSP_PARAMETER	_IOR('H', 0xfe, struct snd_firewire_motu_register_dsp_parameter)
 
 #define SNDRV_FIREWIRE_TYPE_DICE	1
 #define SNDRV_FIREWIRE_TYPE_FIREWORKS	2

sound/firewire/motu/motu-hwdep.c

@@ -199,6 +199,27 @@ static int hwdep_ioctl(struct snd_hwdep *hwdep, struct file *file,
 
 		return 0;
 	}
+	case SNDRV_FIREWIRE_IOCTL_MOTU_REGISTER_DSP_PARAMETER:
+	{
+		struct snd_firewire_motu_register_dsp_parameter *param;
+		int err;
+
+		if (!(motu->spec->flags & SND_MOTU_SPEC_REGISTER_DSP))
+			return -ENXIO;
+
+		param = kzalloc(sizeof(*param), GFP_KERNEL);
+		if (!param)
+			return -ENOMEM;
+
+		snd_motu_register_dsp_message_parser_copy_parameter(motu, param);
+
+		err = copy_to_user((void __user *)arg, param, sizeof(*param));
+		kfree(param);
+		if (err)
+			return -EFAULT;
+
+		return 0;
+	}
 	default:
 		return -ENOIOCTLCMD;
 	}

sound/firewire/motu/motu-register-dsp-message-parser.c

@@ -299,3 +299,14 @@ void snd_motu_register_dsp_message_parser_copy_meter(struct snd_motu *motu,
 	memcpy(meter, &parser->meter, sizeof(*meter));
 	spin_unlock_irqrestore(&parser->lock, flags);
 }
+
+void snd_motu_register_dsp_message_parser_copy_parameter(struct snd_motu *motu,
+					struct snd_firewire_motu_register_dsp_parameter *param)
+{
+	struct msg_parser *parser = motu->message_parser;
+	unsigned long flags;
+
+	spin_lock_irqsave(&parser->lock, flags);
+	memcpy(param, &parser->param, sizeof(*param));
+	spin_unlock_irqrestore(&parser->lock, flags);
+}

sound/firewire/motu/motu.h

@@ -280,7 +280,8 @@ void snd_motu_register_dsp_message_parser_parse(struct snd_motu *motu, const str
 					unsigned int desc_count, unsigned int data_block_quadlets);
 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);
 
 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);