Fix AVR clock setup; add SPI driver

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3721 42af7a65-404d-4744-a932-0658087f49c3

12 files changed, 696 insertions, 14 deletions

diff --git a/nuttx/arch/avr/src/at90usb/Make.defs b/nuttx/arch/avr/src/at90usb/Make.defs
index e3559c0dc..706eca544 100644
--- a/nuttx/arch/avr/src/at90usb/Make.defs
+++ b/nuttx/arch/avr/src/at90usb/Make.defs
@@ -54,6 +54,10 @@ ifeq ($(CONFIG_ARCH_STACKDUMP),y)
 CMN_CSRCS	+= up_dumpstate.c
 endif
 
+ifeq ($(CONFIG_AVR_SPI),y)
+CMN_CSRCS	+= up_spi.c
+endif
+
 # Required AT90USB files
 
 CHIP_ASRCS	= at90usb_exceptions.S
diff --git a/nuttx/arch/avr/src/at90usb/at90usb_lowinit.c b/nuttx/arch/avr/src/at90usb/at90usb_lowinit.c
index 5f8b2e432..e446fcf13 100644
--- a/nuttx/arch/avr/src/at90usb/at90usb_lowinit.c
+++ b/nuttx/arch/avr/src/at90usb/at90usb_lowinit.c
@@ -39,6 +39,7 @@
 
 #include <nuttx/config.h>
 #include <avr/wdt.h>
+#include <avr/power.h>
 
 #include "at90usb_config.h"
 #include "up_internal.h"
@@ -127,6 +128,10 @@ void up_lowinit(void)
 
   up_wdtinit();
 
+  /* Set the system clock divider to 1 */
+
+  clock_prescale_set(clock_div_1);
+
   /* Initialize a console (probably a serial console) */
 
   up_consoleinit();
diff --git a/nuttx/arch/avr/src/at90usb/at90usb_memorymap.h b/nuttx/arch/avr/src/at90usb/at90usb_memorymap.h
index c312a7cca..71635d383 100644
--- a/nuttx/arch/avr/src/at90usb/at90usb_memorymap.h
+++ b/nuttx/arch/avr/src/at90usb/at90usb_memorymap.h
@@ -46,12 +46,6 @@
  * Pre-processor Definitions
  ************************************************************************************/
 
-/* Physical memory map */
-# warning "Missing Definitions"
-
-/* Peripheral Address Map */
-# warning "Missing Definitions"
-
 /************************************************************************************
  * Public Types
  ************************************************************************************/
diff --git a/nuttx/arch/avr/src/at90usb/chip.h b/nuttx/arch/avr/src/at90usb/chip.h
index facc65ec1..c5f2c48b3 100644
--- a/nuttx/arch/avr/src/at90usb/chip.h
+++ b/nuttx/arch/avr/src/at90usb/chip.h
@@ -48,7 +48,7 @@
 
 /* Define features for supported chip in the ATMEGA family */
 
-#if 0
+#if 1
 #else
 #  error "Unsupported AVR chip"
 #endif
diff --git a/nuttx/arch/avr/src/atmega/Make.defs b/nuttx/arch/avr/src/atmega/Make.defs
index a761b4938..16f0f5a62 100644
--- a/nuttx/arch/avr/src/atmega/Make.defs
+++ b/nuttx/arch/avr/src/atmega/Make.defs
@@ -54,6 +54,10 @@ ifeq ($(CONFIG_ARCH_STACKDUMP),y)
 CMN_CSRCS	+= up_dumpstate.c
 endif
 
+ifeq ($(CONFIG_AVR_SPI),y)
+CMN_CSRCS	+= up_spi.c
+endif
+
 # Required ATMEGA files
 
 CHIP_ASRCS	= atmega_exceptions.S
diff --git a/nuttx/arch/avr/src/atmega/atmega_lowinit.c b/nuttx/arch/avr/src/atmega/atmega_lowinit.c
index 417f4e2eb..5802a22f0 100644
--- a/nuttx/arch/avr/src/atmega/atmega_lowinit.c
+++ b/nuttx/arch/avr/src/atmega/atmega_lowinit.c
@@ -39,6 +39,7 @@
 
 #include <nuttx/config.h>
 #include <avr/wdt.h>
+#include <avr/power.h>
 
 #include "atmega_config.h"
 #include "up_internal.h"
@@ -127,6 +128,10 @@ void up_lowinit(void)
 
   up_wdtinit();
 
+  /* Set the system clock divider to 1 */
+
+  clock_prescale_set(clock_div_1);
+
   /* Initialize a console (probably a serial console) */
 
   up_consoleinit();
diff --git a/nuttx/arch/avr/src/atmega/atmega_memorymap.h b/nuttx/arch/avr/src/atmega/atmega_memorymap.h
index a509f7657..7b990754c 100644
--- a/nuttx/arch/avr/src/atmega/atmega_memorymap.h
+++ b/nuttx/arch/avr/src/atmega/atmega_memorymap.h
@@ -46,12 +46,6 @@
  * Pre-processor Definitions
  ************************************************************************************/
 
-/* Physical memory map */
-# warning "Missing Definitions"
-
-/* Peripheral Address Map */
-# warning "Missing Definitions"
-
 /************************************************************************************
  * Public Types
  ************************************************************************************/
diff --git a/nuttx/arch/avr/src/atmega/chip.h b/nuttx/arch/avr/src/atmega/chip.h
index 7f114a604..0e3f779ab 100644
--- a/nuttx/arch/avr/src/atmega/chip.h
+++ b/nuttx/arch/avr/src/atmega/chip.h
@@ -48,7 +48,7 @@
 
 /* Define features for supported chip in the ATMEGA family */
 
-#if 0
+#if 1
 #else
 #  error "Unsupported AVR chip"
 #endif
diff --git a/nuttx/arch/avr/src/avr/avr_internal.h b/nuttx/arch/avr/src/avr/avr_internal.h
index 21906c79d..841b8376a 100644
--- a/nuttx/arch/avr/src/avr/avr_internal.h
+++ b/nuttx/arch/avr/src/avr/avr_internal.h
@@ -42,6 +42,7 @@
 
 #ifndef __ASSEMBLY__
 #  include <stdint.h>
+#  include <stdbool.h>
 #endif
 
 /****************************************************************************
@@ -90,12 +91,96 @@ extern uint16_t g_heapbase;
 
 #ifndef __ASSEMBLY__
 
+/************************************************************************************
+ * Name:  up_copystate
+ *
+ * Description:
+ *   Copy the contents of a register state save structure from one location to
+ *   another.
+ *
+ ************************************************************************************/
+
 extern void up_copystate(uint8_t *dest, uint8_t *src);
+
+/************************************************************************************
+ * Name:  up_saveusercontext
+ *
+ * Description:
+ *   Save the register context of the currently executing (user) thread.
+ *
+ ************************************************************************************/
+
 extern int  up_saveusercontext(uint8_t *saveregs);
+
+/************************************************************************************
+ * Name:  up_fullcontextrestore
+ *
+ * Description:
+ *   Restore the full context of a saved thread/task.
+ *
+ ************************************************************************************/
+
 extern void up_fullcontextrestore(uint8_t *restoreregs) __attribute__ ((noreturn));
+
+/************************************************************************************
+ * Name:  up_switchcontext
+ *
+ * Description:
+ *   Switch from one thread/task context to another.
+ *
+ ************************************************************************************/
+
 extern void up_switchcontext(uint8_t *saveregs, uint8_t *restoreregs);
+
+/************************************************************************************
+ * Name:  up_doirq
+ *
+ * Description:
+ *   Dispatch an interrupt.
+ *
+ ************************************************************************************/
+
 extern uint8_t *up_doirq(uint8_t irq, uint8_t *regs);
 
+/************************************************************************************
+ * Name:  avr_spiselect, avr_spitatus, and avr_spicmddata
+ *
+ * Description:
+ *   These external functions must be provided by board-specific logic.  They are
+ *   implementations of the select, status, and cmddata methods of the SPI interface
+ *   defined by struct spi_ops_s (see include/nuttx/spi.h). All other methods 
+ *   including up_spiinitialize()) are provided by common LPC17xx logic.  To use
+ *   this common SPI logic on your board:
+ *
+ *   1. Provide logic in up_boardinitialize() to configure SPI chip select
+ *      pins.
+ *   2. Provide avr_spiselect() and avr_spistatus() functions in your board-specific
+ *      logic.  These functions will perform chip selection and status operations
+ *      using GPIOs in the way your board is configured.
+ *   2. If CONFIG_SPI_CMDDATA is defined in the NuttX configuration, provide the
+ *      avr_spicmddata() function in your board-specific logic.  This functions will
+ *      perform cmd/data selection operations using GPIOs in the way your board is
+ *      configured.
+ *   3. Add a call to up_spiinitialize() in your low level application
+ *      initialization logic
+ *   4. The handle returned by up_spiinitialize() may then be used to bind the
+ *      SPI driver to higher level logic (e.g., calling 
+ *      mmcsd_spislotinitialize(), for example, will bind the SPI driver to
+ *      the SPI MMC/SD driver).
+ *
+ ************************************************************************************/
+
+struct spi_dev_s;
+enum spi_dev_e;
+
+#ifdef CONFIG_AVR_SPI
+extern void  avr_spiselect(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected);
+extern uint8_t avr_spistatus(FAR struct spi_dev_s *dev, enum spi_dev_e devid);
+#ifdef CONFIG_SPI_CMDDATA
+extern int avr_spicmddata(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool cmd);
+#endif
+#endif
+
 #endif /* __ASSEMBLY__ */
 #endif  /* __ARCH_AVR_SRC_AVR_AVR_INTERNAL_H */
 
diff --git a/nuttx/arch/avr/src/avr/up_spi.c b/nuttx/arch/avr/src/avr/up_spi.c
new file mode 100644
index 000000000..7a38d5c97
--- /dev/null
+++ b/nuttx/arch/avr/src/avr/up_spi.c
@@ -0,0 +1,537 @@
+/****************************************************************************
+ * arch/arm/src/avr/up_spi.c
+ *
+ *   Copyright (C) 2011 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <semaphore.h>
+#include <errno.h>
+#include <debug.h>
+
+#include <arch/board/board.h>
+#include <nuttx/arch.h>
+#include <nuttx/spi.h>
+
+#include <avr/io.h>
+#include <avr/power.h>
+
+#include "up_internal.h"
+#include "up_arch.h"
+
+#include "chip.h"
+#include "avr_internal.h"
+
+#ifdef CONFIG_AVR_SPI
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/* Enables debug output from this file (needs CONFIG_DEBUG too) */
+
+#undef SPI_DEBUG     /* Define to enable debug */
+#undef SPI_VERBOSE   /* Define to enable verbose debug */
+
+#ifdef SPI_DEBUG
+#  define spidbg  lldbg
+#  ifdef SPI_VERBOSE
+#    define spivdbg lldbg
+#  else
+#    define spivdbg(x...)
+#  endif
+#else
+#  undef SPI_VERBOSE
+#  define spidbg(x...)
+#  define spivdbg(x...)
+#endif
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+struct avr_spidev_s
+{
+  struct spi_dev_s spidev;     /* Externally visible part of the SPI interface */
+#ifndef CONFIG_SPI_OWNBUS
+  sem_t            exclsem;    /* Held while chip is selected for mutual exclusion */
+  uint32_t         frequency;  /* Requested clock frequency */
+  uint32_t         actual;     /* Actual clock frequency */
+  uint8_t          mode;       /* Mode 0,1,2,3 */
+#endif
+};
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/* SPI methods */
+
+#ifndef CONFIG_SPI_OWNBUS
+static int      spi_lock(FAR struct spi_dev_s *dev, bool lock);
+#endif
+static uint32_t spi_setfrequency(FAR struct spi_dev_s *dev, uint32_t frequency);
+static void     spi_setmode(FAR struct spi_dev_s *dev, enum spi_mode_e mode);
+static void     spi_setbits(FAR struct spi_dev_s *dev, int nbits);
+static uint16_t spi_send(FAR struct spi_dev_s *dev, uint16_t ch);
+static void     spi_sndblock(FAR struct spi_dev_s *dev, FAR const void *buffer, size_t nwords);
+static void     spi_recvblock(FAR struct spi_dev_s *dev, FAR void *buffer, size_t nwords);
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct spi_ops_s g_spiops =
+{
+#ifndef CONFIG_SPI_OWNBUS
+  .lock              = spi_lock,
+#endif
+  .select            = avr_spiselect,
+  .setfrequency      = spi_setfrequency,
+  .setmode           = spi_setmode,
+  .setbits           = spi_setbits,
+  .status            = avr_spistatus,
+#ifdef CONFIG_SPI_CMDDATA
+  .cmddata           = avr_spicmddata,
+#endif
+  .send              = spi_send,
+  .sndblock          = spi_sndblock,
+  .recvblock         = spi_recvblock,
+  .registercallback  = 0,                 /* Not implemented */
+};
+
+static struct avr_spidev_s g_spidev =
+{
+  .spidev            = { &g_spiops },
+}; 
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: spi_lock
+ *
+ * Description:
+ *   On SPI busses where there are multiple devices, it will be necessary to
+ *   lock SPI to have exclusive access to the busses for a sequence of
+ *   transfers.  The bus should be locked before the chip is selected. After
+ *   locking the SPI bus, the caller should then also call the setfrequency,
+ *   setbits, and setmode methods to make sure that the SPI is properly
+ *   configured for the device.  If the SPI buss is being shared, then it
+ *   may have been left in an incompatible state.
+ *
+ * Input Parameters:
+ *   dev  - Device-specific state data
+ *   lock - true: Lock spi bus, false: unlock SPI bus
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+#ifndef CONFIG_SPI_OWNBUS
+static int spi_lock(FAR struct spi_dev_s *dev, bool lock)
+{
+  FAR struct avr_spidev_s *priv = (FAR struct avr_spidev_s *)dev;
+
+  if (lock)
+    {
+      /* Take the semaphore (perhaps waiting) */
+
+      while (sem_wait(&priv->exclsem) != 0)
+        {
+          /* The only case that an error should occur here is if the wait was awakened
+           * by a signal.
+           */
+
+          ASSERT(errno == EINTR);
+        }
+    }
+  else
+    {
+      (void)sem_post(&priv->exclsem);
+    }
+  return OK;
+}
+#endif
+
+/****************************************************************************
+ * Name: spi_setfrequency
+ *
+ * Description:
+ *   Set the SPI frequency.
+ *
+ * Input Parameters:
+ *   dev -       Device-specific state data
+ *   frequency - The SPI frequency requested
+ *
+ * Returned Value:
+ *   Returns the actual frequency selected
+ *
+ ****************************************************************************/
+
+static uint32_t spi_setfrequency(FAR struct spi_dev_s *dev, uint32_t frequency)
+{
+  uint32_t actual;
+#ifndef CONFIG_SPI_OWNBUS
+  FAR struct avr_spidev_s *priv = (FAR struct avr_spidev_s *)dev;
+
+  /* Has the request frequency changed? */
+
+  if (frequency != priv->frequency)
+    {
+#endif
+      /* Read the SPI status and control registers, clearing all divider bits */
+
+      uint8_t spcr = SPCR & ~((1 << SPR0) | (1 << SPR1));
+      uint8_t spsr = SPSR & ~(1 << SPI2X);
+
+      /* Select the best divider bits */
+
+      if (frequency >= BOARD_CPU_CLOCK / 2)
+        {
+          spsr  |= (1 << SPI2X);
+          actual = BOARD_CPU_CLOCK / 2;
+        }
+      else if (frequency >= BOARD_CPU_CLOCK / 4)
+        {
+          actual = BOARD_CPU_CLOCK / 4;
+        }
+      else if (frequency >= BOARD_CPU_CLOCK / 8)
+        {
+          spcr  |= (1 << SPR0);
+          spsr  |= (1 << SPI2X);
+          actual = BOARD_CPU_CLOCK / 8;
+        }
+      else if (frequency >= BOARD_CPU_CLOCK / 16)
+        {
+          spcr  |= (1 << SPR0);
+          actual = BOARD_CPU_CLOCK / 16;
+        }
+      else if (frequency >= BOARD_CPU_CLOCK / 32)
+        {
+          spcr  |= (1 << SPR1);
+          spsr  |= (1 << SPI2X);
+          actual = BOARD_CPU_CLOCK / 32;
+        }
+      else if (frequency >= BOARD_CPU_CLOCK / 64)
+        {
+          spcr  |= (1 << SPR1);
+          actual = BOARD_CPU_CLOCK / 64;
+        }
+      else /* if (frequency >= BOARD_CPU_CLOCK / 128) */
+        {
+          spcr  |= (1 << SPR0)|(1 << SPR1);
+          actual = BOARD_CPU_CLOCK / 128;
+        }
+
+      /* Save the frequency setting */
+
+#ifndef CONFIG_SPI_OWNBUS
+      priv->frequency = frequency;
+      priv->actual    = actual;
+    }
+  else
+    {
+      actual          = priv->actual;
+    }
+#endif
+
+  spidbg("Frequency %d->%d\n", frequency, actual);
+  return actual;
+}
+
+/****************************************************************************
+ * Name: spi_setmode
+ *
+ * Description:
+ *   Set the SPI mode. Optional.  See enum spi_mode_e for mode definitions
+ *
+ * Input Parameters:
+ *   dev -  Device-specific state data
+ *   mode - The SPI mode requested
+ *
+ * Returned Value:
+ *   none
+ *
+ ****************************************************************************/
+
+static void spi_setmode(FAR struct spi_dev_s *dev, enum spi_mode_e mode)
+{
+#ifndef CONFIG_SPI_OWNBUS
+  FAR struct avr_spidev_s *priv = (FAR struct avr_spidev_s *)dev;
+
+  /* Has the mode changed? */
+
+  if (mode != priv->mode)
+    {
+#endif
+      uint8_t regval;
+
+      /* Yes... Set SPI CR appropriately */
+
+      regval = SPCR;
+      regval &= ~((1 << CPOL) | (1 << CPHA));
+
+      switch (mode)
+        {
+        case SPIDEV_MODE0: /* CPOL=0; CPHA=0 */
+          break;
+ 
+        case SPIDEV_MODE1: /* CPOL=0; CPHA=1 */
+          regval |= (1 << CPHA);
+          break;
+ 
+        case SPIDEV_MODE2: /* CPOL=1; CPHA=0 */
+          regval |= (1 << CPOL);
+          break;
+ 
+        case SPIDEV_MODE3: /* CPOL=1; CPHA=1 */
+          regval |= ((1 << CPOL) | (1 << CPHA));
+          break;
+ 
+        default:
+          DEBUGASSERT(FALSE);
+          return;
+        }
+
+      SPSR = regval;
+
+      /* Save the mode so that subsequent re-configuratins will be faster */
+
+#ifndef CONFIG_SPI_OWNBUS
+      priv->mode = mode;
+    }
+#endif
+}
+
+/****************************************************************************
+ * Name: spi_setbits
+ *
+ * Description:
+ *   Set the number if bits per word.
+ *
+ * Input Parameters:
+ *   dev -  Device-specific state data
+ *   nbits - The number of bits requests (only nbits == 8 is supported)
+ *
+ * Returned Value:
+ *   none
+ *
+ ****************************************************************************/
+
+static void spi_setbits(FAR struct spi_dev_s *dev, int nbits)
+{
+  DEBUGASSERT(dev && nbits == 8);
+}
+
+/****************************************************************************
+ * Name: spi_send
+ *
+ * Description:
+ *   Exchange one word on SPI
+ *
+ * Input Parameters:
+ *   dev - Device-specific state data
+ *   wd  - The word to send.  the size of the data is determined by the
+ *         number of bits selected for the SPI interface.
+ *
+ * Returned Value:
+ *   response
+ *
+ ****************************************************************************/
+
+static uint16_t spi_send(FAR struct spi_dev_s *dev, uint16_t wd)
+{
+  /* Write the data to transmitted to the SPI Data Register */
+
+  SPDR = (uint8_t)wd;
+
+  /* Wait for transmission to complete */
+
+  while (!(SPSR & (1<<SPIF)));
+
+  /* Then return the received value */
+
+  return (uint16_t)SPDR;
+}
+
+/*************************************************************************
+ * Name: spi_sndblock
+ *
+ * Description:
+ *   Send a block of data on SPI
+ *
+ * Input Parameters:
+ *   dev -    Device-specific state data
+ *   buffer - A pointer to the buffer of data to be sent
+ *   nwords - the length of data to send from the buffer in number of words.
+ *            The wordsize is determined by the number of bits-per-word
+ *            selected for the SPI interface.  If nbits <= 8, the data is
+ *            packed into uint8_t's; if nbits >8, the data is packed into
+ *            uint16_t's
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+static void spi_sndblock(FAR struct spi_dev_s *dev, FAR const void *buffer, size_t nwords)
+{
+  FAR uint8_t *ptr = (FAR uint8_t*)buffer;
+
+  spidbg("nwords: %d\n", nwords);
+  while (nwords-- > 0)
+  {
+    (void)spi_send(dev, (uint16_t)*ptr++);
+  }
+}
+
+/****************************************************************************
+ * Name: spi_recvblock
+ *
+ * Description:
+ *   Revice a block of data from SPI
+ *
+ * Input Parameters:
+ *   dev -    Device-specific state data
+ *   buffer - A pointer to the buffer in which to recieve data
+ *   nwords - the length of data that can be received in the buffer in number
+ *            of words.  The wordsize is determined by the number of bits-
+ *            per-wordselected for the SPI interface.  If nbits <= 8, the
+ *            data is packed into uint8_t's; if nbits >8, the data is packed
+ *            into uint16_t's
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+static void spi_recvblock(FAR struct spi_dev_s *dev, FAR void *buffer, size_t nwords)
+{
+  FAR uint8_t *ptr = (FAR uint8_t*)buffer;
+
+  spidbg("nwords: %d\n", nwords);
+  while (nwords-- > 0)
+  {
+    *ptr++ = spi_send(dev, (uint16_t)0xff);
+  }
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_spiinitialize
+ *
+ * Description:
+ *   Initialize the selected SPI port
+ *
+ * Input Parameter:
+ *   Port number (for hardware that has mutiple SPI interfaces)
+ *
+ * Returned Value:
+ *   Valid SPI device structure reference on succcess; a NULL on failure
+ *
+ ****************************************************************************/
+
+FAR struct spi_dev_s *up_spiinitialize(int port)
+{
+  FAR struct avr_spidev_s *priv = &g_spidev;
+  irqstate_t flags;
+  uint8_t regval;
+
+  /* Make sure that clocks are provided to the SPI module */
+
+  flags = irqsave();
+  power_spi_enable();
+
+  /* Set MOSI and SCK as outputs, all others are inputs (default on reset):
+   *
+   * PB3: PDO/MISO/PCINT3
+   * PB2: PDI/MOSI/PCINT2
+   * PB1: SCK/PCINT1
+   * PB0: SS/PCINT0
+   */
+
+  DDRB |= (1 << 2) | (1 << 1);
+
+  /* - Enable SPI
+   * - Set Master
+   * - Set clock rate oscillator/4
+   * - Set CPOL for SPI clock mode 0
+   */
+
+  SPCR = (1 << SPE) | (1 << MSTR);
+
+  /* Set clock rate to f(osc)/8 */
+  /* SPSR |= (1 << 0); */
+
+  /* Clear status flags by reading them */
+
+  regval = SPSR;
+  regval = SPDR;
+
+  /* Set the initial SPI configuration */
+
+#ifndef CONFIG_SPI_OWNBUS
+  priv->frequency = 0;
+  priv->mode      = SPIDEV_MODE0;
+#endif
+
+  /* Select a default frequency of approx. 400KHz */
+
+  spi_setfrequency((FAR struct spi_dev_s *)priv, 400000);
+
+  /* Initialize the SPI semaphore that enforces mutually exclusive access */
+
+#ifndef CONFIG_SPI_OWNBUS
+  sem_init(&priv->exclsem, 0, 1);
+#endif
+  return &priv->spidev;
+}
+#endif /* CONFIG_AVR_SPI */
+
diff --git a/nuttx/arch/avr/src/avr32/avr32_internal.h b/nuttx/arch/avr/src/avr32/avr32_internal.h
index 9cf714b01..58aa555aa 100644
--- a/nuttx/arch/avr/src/avr32/avr32_internal.h
+++ b/nuttx/arch/avr/src/avr32/avr32_internal.h
@@ -90,10 +90,55 @@ extern uint32_t g_heapbase;
 
 #ifndef __ASSEMBLY__
 
+/************************************************************************************
+ * Name:  up_copystate
+ *
+ * Description:
+ *   Copy the contents of a register state save structure from one location to
+ *   another.
+ *
+ ************************************************************************************/
+
 extern void up_copystate(uint32_t *dest, uint32_t *src);
+
+/************************************************************************************
+ * Name:  up_saveusercontext
+ *
+ * Description:
+ *   Save the register context of the currently executing (user) thread.
+ *
+ ************************************************************************************/
+
 extern int  up_saveusercontext(uint32_t *saveregs);
+
+/************************************************************************************
+ * Name:  up_fullcontextrestore
+ *
+ * Description:
+ *   Restore the full context of a saved thread/task.
+ *
+ ************************************************************************************/
+
 extern void up_fullcontextrestore(uint32_t *restoreregs) __attribute__ ((noreturn));
+
+/************************************************************************************
+ * Name:  up_switchcontext
+ *
+ * Description:
+ *   Switch from one thread/task context to another.
+ *
+ ************************************************************************************/
+
 extern void up_switchcontext(uint32_t *saveregs, uint32_t *restoreregs);
+
+/************************************************************************************
+ * Name:  up_doirq
+ *
+ * Description:
+ *   Dispatch an interrupt.
+ *
+ ************************************************************************************/
+
 extern uint32_t *up_doirq(int irq, uint32_t *regs);
 
 #endif /* __ASSEMBLY__ */
diff --git a/nuttx/arch/avr/src/common/up_assert.c b/nuttx/arch/avr/src/common/up_assert.c
index b2cd8ae86..a0ba2355e 100644
--- a/nuttx/arch/avr/src/common/up_assert.c
+++ b/nuttx/arch/avr/src/common/up_assert.c
@@ -69,6 +69,15 @@
 #  define CONFIG_PRINT_TASKNAME 1
 #endif
 
+/* If there is going to be stackdump output, then we should turn on output
+ * here unconditionally as well.
+ */
+
+#ifdef CONFIG_ARCH_STACKDUMP
+#  undef  lldbg
+#  define lldbg lib_lowprintf
+#endif
+
 /****************************************************************************
  * Private Data
  ****************************************************************************/