SAMA5 SSC: Add support for loopback mode. Plus unrelated Make.defs file from the last checkin

ChangeLog

@@ -6025,3 +6025,6 @@
 	  that must be available to audio applications.  If it was left in the
 	  audio/ directory then it would not be available to applications in the
 	  NuttX Kernel build (2013-11-10).
+	* arch/arm/src/sama5/sam_ssc.c and Kconfig:  Add configurable support
+	  for SSC loopback mode (2013-11-10).
+

arch/arm/src/sama5/Kconfig

@@ -1528,6 +1528,17 @@ config SAMA5_SSC0_MCKDIV_SAMPLERATE
 		divider to obtain that bitrate (up to 4095).  If the bitrate can be realized
 		by dividing down the MCK/2, a compile time error will occur.
 
+config SAMA5_SSC0_LOOPBACK
+	bool "Loopback mode"
+	default n
+	depends on SAMA5_SSC0_TX && SAMA5_SSC0_RX
+	---help---
+		If both the receiver and transmitter are enabled, then the SSC can
+		be configured in loopback mode.  This setting selects SSC loopback
+		and will cause the LOOP bit to be set in the SSC_RFMR regsiter. In
+		this case, RD is connected to TD, RF is connected to TF and RK is
+		connected to TK.
+
 endif # SAMA5_SSC0
 
 if SAMA5_SSC1
@@ -1669,6 +1680,17 @@ config SAMA5_SSC1_MCKDIV_SAMPLERATE
 		divider to obtain that bitrate (up to 4095).  If the bitrate can be realized
 		by dividing down the MCK/2, a compile time error will occur.
 
+config SAMA5_SSC1_LOOPBACK
+	bool "Loopback mode"
+	default n
+	depends on SAMA5_SSC1_TX && SAMA5_SSC1_RX
+	---help---
+		If both the receiver and transmitter are enabled, then the SSC can
+		be configured in loopback mode.  This setting selects SSC loopback
+		and will cause the LOOP bit to be set in the SSC_RFMR regsiter. In
+		this case, RD is connected to TD, RF is connected to TF and RK is
+		connected to TK.
+
 endif # SAMA5_SSC1
 
 config SAMA5_SSC_DMADEBUG

arch/arm/src/sama5/sam_ssc.c

@@ -260,6 +260,7 @@ struct sam_ssc_s
   uint16_t master:1;           /* True: Master mode transfers */
   uint16_t rx:1;               /* True: RX transfers supported */
   uint16_t tx:1;               /* True: TX transfers supported */
+  uint16_t loopback:1;         /* True: Loopback mode */
   uint16_t sscno:1;            /* SSC controller number (0 or 1) */
   uint16_t rxclk:2;            /* Receiver clock source. See SSC_CLKSRC_* definitions */
   uint16_t txclk:2;            /* Transmitter clock source. See SSC_CLKSRC_* definitions */
@@ -2132,7 +2133,7 @@ static int ssc_rx_configure(struct sam_ssc_s *priv)
    * Currently hardcoded to:
    *
    *  SSC_RFMR_DATLEN(n)    'n' deterimined by configuration
-   *  SSC_RFMR_LOOP         Loop mode not selected
+   *  SSC_RFMR_LOOP         Determined by configuration
    *  SSC_RFMR_MSBF         Most significant bit first
    *  SSC_RFMR_DATNB(n)     Data number 'n' per frame (hard-coded)
    *  SSC_RFMR_FSLEN(0)     Receive frame sync length = 0
@@ -2144,6 +2145,14 @@ static int ssc_rx_configure(struct sam_ssc_s *priv)
   regval = (SSC_RFMR_DATLEN(CONFIG_SAMA5_SSC0_DATALEN - 1) | SSC_RFMR_MSBF |
             SSC_RFMR_DATNB(SSC_DATNB - 1) | SSC_RFMR_FSLEN(0) |
             SSC_RFMR_FSOS_NONE | SSC_RFMR_FSLENEXT(0));
+
+  /* Loopback mode? */
+
+  if (priv->loopback)
+    {
+      regval |= SSC_RFMR_LOOP;
+    }
+
   ssc_putreg(priv, SAM_SSC_RFMR_OFFSET, regval);
 
 #else
@@ -2614,6 +2623,15 @@ static void ssc0_configure(struct sam_ssc_s *priv)
 
 #endif /* CONFIG_SAMA5_SSC0_TX */
 
+  /* Set/clear loopback mode */
+
+#if defined(CONFIG_SAMA5_SSC0_TX) && defined(CONFIG_SAMA5_SSC0_TX) && \
+    defined(SAMA5_SSC0_LOOPBACK)
+  priv->loopback = true;
+#else
+  priv->loopback = false;
+#endif
+
   /* Does the receiver or transmitter need to have the MCK divider set up? */
 
 #if defined(SSC0_HAVE_MCK2)
@@ -2740,6 +2758,15 @@ static void ssc1_configure(struct sam_ssc_s *priv)
 
 #endif /* CONFIG_SAMA5_SSC1_TX */
 
+  /* Set/clear loopback mode */
+
+#if defined(CONFIG_SAMA5_SSC1_TX) && defined(CONFIG_SAMA5_SSC1_TX) && \
+    defined(SAMA5_SSC1_LOOPBACK)
+  priv->loopback = true;
+#else
+  priv->loopback = false;
+#endif
+
   /* Does the receiver or transmitter need to have the MCK divider set up? */
 
 #if defined(SSC1_HAVE_MCK2)

libc/audio/Make.defs

@@ -0,0 +1,43 @@
+############################################################################
+# libc/audio/Make.defs
+#
+#   Copyright (C) 2013 Gregory Nutt. All rights reserved.
+#   Author: Gregory Nutt <gnutt@nuttx.org>
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 3. Neither the name NuttX nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+############################################################################
+
+ifeq ($(CONFIG_AUDIO),y)
+CSRCS += lib_buffer.c
+
+# Add the misc directory to the build
+
+DEPPATH += --dep-path audio
+VPATH += :audio
+endif