ALSA: hdspm - Allow the TCO and SYNC-IN to be used in slave mode

When using the additional Time Code Option module in slave mode or the
SYNC-In wordclock connector, the sample rate needs to be returned by
hdspm_external_sample_rate().

Since this sample rate may contain any value with 1Hz granularity, we
need to round it to a common rate as done by the OSX driver.

[Fixed missing function declarations by tiwai]
Signed-off-by: Adrian Knoth <adi@drcomp.erfurt.thur.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/rme9652/hdspm.c

@@ -1076,6 +1076,20 @@ static int snd_hdspm_use_is_exclusive(struct hdspm *hdspm)
 	return ret;
 }
 
+/* round arbitary sample rates to commonly known rates */
+static int hdspm_round_frequency(int rate)
+{
+	if (rate < 38050)
+		return 32000;
+	if (rate < 46008)
+		return 44100;
+	else
+		return 48000;
+}
+
+static int hdspm_tco_sync_check(struct hdspm *hdspm);
+static int hdspm_sync_in_sync_check(struct hdspm *hdspm);
+
 /* check for external sample rate */
 static int hdspm_external_sample_rate(struct hdspm *hdspm)
 {
@@ -1217,6 +1231,30 @@ static int hdspm_external_sample_rate(struct hdspm *hdspm)
 				break;
 			}
 
+		} /* endif HDSPM_madiLock */
+
+		/* check sample rate from TCO or SYNC_IN */
+		{
+			bool is_valid_input = 0;
+			bool has_sync = 0;
+
+			syncref = hdspm_autosync_ref(hdspm);
+			if (HDSPM_AUTOSYNC_FROM_TCO == syncref) {
+				is_valid_input = 1;
+				has_sync = (HDSPM_SYNC_CHECK_SYNC ==
+					hdspm_tco_sync_check(hdspm));
+			} else if (HDSPM_AUTOSYNC_FROM_SYNC_IN == syncref) {
+				is_valid_input = 1;
+				has_sync = (HDSPM_SYNC_CHECK_SYNC ==
+					hdspm_sync_in_sync_check(hdspm));
+			}
+
+			if (is_valid_input && has_sync) {
+				rate = hdspm_round_frequency(
+					hdspm_get_pll_freq(hdspm));
+			}
+		}
+
 		/* QS and DS rates normally can not be detected
 		 * automatically by the card. Only exception is MADI
 		 * in 96k frame mode.
@@ -1232,7 +1270,6 @@ static int hdspm_external_sample_rate(struct hdspm *hdspm)
 					HDSPM_DoubleSpeed)
 				rate *= 2;
 		}
-		}
 		break;
 	}