ALSA: iec958: Split status creation and fill

In some situations, like a codec probe, we need to provide an IEC status
default but don't have access to the sampling rate and width yet since
no stream has been configured yet.

Each and every driver has its own default, whereas the core iec958 code
also has some buried in the snd_pcm_create_iec958_consumer functions.

Let's split these functions in two to provide a default that doesn't
rely on the sampling rate and width, and another function to fill them
when available.
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20210525132354.297468-3-maxime@cerno.tech

include/sound/pcm_iec958.h

@@ -4,6 +4,14 @@
 
 #include <linux/types.h>
 
+int snd_pcm_create_iec958_consumer_default(u8 *cs, size_t len);
+
+int snd_pcm_fill_iec958_consumer(struct snd_pcm_runtime *runtime, u8 *cs,
+				 size_t len);
+
+int snd_pcm_fill_iec958_consumer_hw_params(struct snd_pcm_hw_params *params,
+					   u8 *cs, size_t len);
+
 int snd_pcm_create_iec958_consumer(struct snd_pcm_runtime *runtime, u8 *cs,
 	size_t len);
 

sound/core/pcm_iec958.c

@@ -9,41 +9,85 @@
 #include <sound/pcm_params.h>
 #include <sound/pcm_iec958.h>
 
-static int create_iec958_consumer(uint rate, uint sample_width,
-				  u8 *cs, size_t len)
+/**
+ * snd_pcm_create_iec958_consumer_default - create default consumer format IEC958 channel status
+ * @cs: channel status buffer, at least four bytes
+ * @len: length of channel status buffer
+ *
+ * Create the consumer format channel status data in @cs of maximum size
+ * @len. When relevant, the configuration-dependant bits will be set as
+ * unspecified.
+ *
+ * Drivers should then call einter snd_pcm_fill_iec958_consumer() or
+ * snd_pcm_fill_iec958_consumer_hw_params() to replace these unspecified
+ * bits by their actual values.
+ *
+ * Drivers may wish to tweak the contents of the buffer after creation.
+ *
+ * Returns: length of buffer, or negative error code if something failed.
+ */
+int snd_pcm_create_iec958_consumer_default(u8 *cs, size_t len)
 {
-	unsigned int fs, ws;
-
 	if (len < 4)
 		return -EINVAL;
 
-	switch (rate) {
-	case 32000:
-		fs = IEC958_AES3_CON_FS_32000;
-		break;
-	case 44100:
-		fs = IEC958_AES3_CON_FS_44100;
-		break;
-	case 48000:
-		fs = IEC958_AES3_CON_FS_48000;
-		break;
-	case 88200:
-		fs = IEC958_AES3_CON_FS_88200;
-		break;
-	case 96000:
-		fs = IEC958_AES3_CON_FS_96000;
-		break;
-	case 176400:
-		fs = IEC958_AES3_CON_FS_176400;
-		break;
-	case 192000:
-		fs = IEC958_AES3_CON_FS_192000;
-		break;
-	default:
+	memset(cs, 0, len);
+
+	cs[0] = IEC958_AES0_CON_NOT_COPYRIGHT | IEC958_AES0_CON_EMPHASIS_NONE;
+	cs[1] = IEC958_AES1_CON_GENERAL;
+	cs[2] = IEC958_AES2_CON_SOURCE_UNSPEC | IEC958_AES2_CON_CHANNEL_UNSPEC;
+	cs[3] = IEC958_AES3_CON_CLOCK_1000PPM | IEC958_AES3_CON_FS_NOTID;
+
+	if (len > 4)
+		cs[4] = IEC958_AES4_CON_WORDLEN_NOTID;
+
+	return len;
+}
+EXPORT_SYMBOL_GPL(snd_pcm_create_iec958_consumer_default);
+
+static int fill_iec958_consumer(uint rate, uint sample_width,
+				u8 *cs, size_t len)
+{
+	if (len < 4)
 		return -EINVAL;
+
+	if ((cs[3] & IEC958_AES3_CON_FS) == IEC958_AES3_CON_FS_NOTID) {
+		unsigned int fs;
+
+		switch (rate) {
+			case 32000:
+				fs = IEC958_AES3_CON_FS_32000;
+				break;
+			case 44100:
+				fs = IEC958_AES3_CON_FS_44100;
+				break;
+			case 48000:
+				fs = IEC958_AES3_CON_FS_48000;
+				break;
+			case 88200:
+				fs = IEC958_AES3_CON_FS_88200;
+				break;
+			case 96000:
+				fs = IEC958_AES3_CON_FS_96000;
+				break;
+			case 176400:
+				fs = IEC958_AES3_CON_FS_176400;
+				break;
+			case 192000:
+				fs = IEC958_AES3_CON_FS_192000;
+				break;
+			default:
+				return -EINVAL;
+		}
+
+		cs[3] &= ~IEC958_AES3_CON_FS;
+		cs[3] |= fs;
 	}
 
-	if (len > 4) {
+	if (len > 4 &&
+	    (cs[4] & IEC958_AES4_CON_WORDLEN) == IEC958_AES4_CON_WORDLEN_NOTID) {
+		unsigned int ws;
+
 		switch (sample_width) {
 		case 16:
 			ws = IEC958_AES4_CON_WORDLEN_20_16;
@@ -64,20 +108,57 @@ static int create_iec958_consumer(uint rate, uint sample_width,
 		default:
 			return -EINVAL;
 		}
-	}
 
-	memset(cs, 0, len);
+		cs[4] &= ~IEC958_AES4_CON_WORDLEN;
+		cs[4] |= ws;
+	}
 
-	cs[0] = IEC958_AES0_CON_NOT_COPYRIGHT | IEC958_AES0_CON_EMPHASIS_NONE;
-	cs[1] = IEC958_AES1_CON_GENERAL;
-	cs[2] = IEC958_AES2_CON_SOURCE_UNSPEC | IEC958_AES2_CON_CHANNEL_UNSPEC;
-	cs[3] = IEC958_AES3_CON_CLOCK_1000PPM | fs;
+	return len;
+}
 
-	if (len > 4)
-		cs[4] = ws;
+/**
+ * snd_pcm_fill_iec958_consumer - Fill consumer format IEC958 channel status
+ * @runtime: pcm runtime structure with ->rate filled in
+ * @cs: channel status buffer, at least four bytes
+ * @len: length of channel status buffer
+ *
+ * Fill the unspecified bits in an IEC958 status bits array using the
+ * parameters of the PCM runtime @runtime.
+ *
+ * Drivers may wish to tweak the contents of the buffer after its been
+ * filled.
+ *
+ * Returns: length of buffer, or negative error code if something failed.
+ */
+int snd_pcm_fill_iec958_consumer(struct snd_pcm_runtime *runtime,
+				 u8 *cs, size_t len)
+{
+	return fill_iec958_consumer(runtime->rate,
+				    snd_pcm_format_width(runtime->format),
+				    cs, len);
+}
+EXPORT_SYMBOL_GPL(snd_pcm_fill_iec958_consumer);
 
-	return len;
+/**
+ * snd_pcm_fill_iec958_consumer_hw_params - Fill consumer format IEC958 channel status
+ * @params: the hw_params instance for extracting rate and sample format
+ * @cs: channel status buffer, at least four bytes
+ * @len: length of channel status buffer
+ *
+ * Fill the unspecified bits in an IEC958 status bits array using the
+ * parameters of the PCM hardware parameters @params.
+ *
+ * Drivers may wish to tweak the contents of the buffer after its been
+ * filled..
+ *
+ * Returns: length of buffer, or negative error code if something failed.
+ */
+int snd_pcm_fill_iec958_consumer_hw_params(struct snd_pcm_hw_params *params,
+					   u8 *cs, size_t len)
+{
+	return fill_iec958_consumer(params_rate(params), params_width(params), cs, len);
 }
+EXPORT_SYMBOL_GPL(snd_pcm_fill_iec958_consumer_hw_params);
 
 /**
  * snd_pcm_create_iec958_consumer - create consumer format IEC958 channel status
@@ -95,9 +176,13 @@ static int create_iec958_consumer(uint rate, uint sample_width,
 int snd_pcm_create_iec958_consumer(struct snd_pcm_runtime *runtime, u8 *cs,
 	size_t len)
 {
-	return create_iec958_consumer(runtime->rate,
-				      snd_pcm_format_width(runtime->format),
-				      cs, len);
+	int ret;
+
+	ret = snd_pcm_create_iec958_consumer_default(cs, len);
+	if (ret < 0)
+		return ret;
+
+	return snd_pcm_fill_iec958_consumer(runtime, cs, len);
 }
 EXPORT_SYMBOL(snd_pcm_create_iec958_consumer);
 
@@ -117,7 +202,12 @@ EXPORT_SYMBOL(snd_pcm_create_iec958_consumer);
 int snd_pcm_create_iec958_consumer_hw_params(struct snd_pcm_hw_params *params,
 					     u8 *cs, size_t len)
 {
-	return create_iec958_consumer(params_rate(params), params_width(params),
-				      cs, len);
+	int ret;
+
+	ret = snd_pcm_create_iec958_consumer_default(cs, len);
+	if (ret < 0)
+		return ret;
+
+	return fill_iec958_consumer(params_rate(params), params_width(params), cs, len);
 }
 EXPORT_SYMBOL(snd_pcm_create_iec958_consumer_hw_params);