ALSA: fireface: share helper function to get current sampling rate and clock source

As long as investigating packet dumps from Fireface 400/800, bits on
status registers for clock synchronization are the same.

This commit moves a parser for a register of clock configuration to
obsolete model-specific operations.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/fireface/ff-transaction.c

@@ -8,6 +8,65 @@
 
 #include "ff.h"
 
+int snd_ff_transaction_get_clock(struct snd_ff *ff, unsigned int *rate,
+				 enum snd_ff_clock_src *src)
+{
+	__le32 reg;
+	u32 data;
+	int err;
+
+	err = snd_fw_transaction(ff->unit, TCODE_READ_QUADLET_REQUEST,
+				 SND_FF_REG_CLOCK_CONFIG, &reg, sizeof(reg), 0);
+	if (err < 0)
+		return err;
+	data = le32_to_cpu(reg);
+
+	/* Calculate sampling rate. */
+	switch ((data >> 1) & 0x03) {
+	case 0x01:
+		*rate = 32000;
+		break;
+	case 0x00:
+		*rate = 44100;
+		break;
+	case 0x03:
+		*rate = 48000;
+		break;
+	case 0x02:
+	default:
+		return -EIO;
+	}
+
+	if (data & 0x08)
+		*rate *= 2;
+	else if (data & 0x10)
+		*rate *= 4;
+
+	/* Calculate source of clock. */
+	if (data & 0x01) {
+		*src = SND_FF_CLOCK_SRC_INTERNAL;
+	} else {
+		/* TODO: 0x00, 0x01, 0x02, 0x06, 0x07? */
+		switch ((data >> 10) & 0x07) {
+		case 0x03:
+			*src = SND_FF_CLOCK_SRC_SPDIF;
+			break;
+		case 0x04:
+			*src = SND_FF_CLOCK_SRC_WORD;
+			break;
+		case 0x05:
+			*src = SND_FF_CLOCK_SRC_LTC;
+			break;
+		case 0x00:
+		default:
+			*src = SND_FF_CLOCK_SRC_ADAT;
+			break;
+		}
+	}
+
+	return 0;
+}
+
 static void finish_transmit_midi_msg(struct snd_ff *ff, unsigned int port,
 				     int rcode)
 {