Add the up_systemreset interface to the samv7 arch. The approach is slightly different in that: 1) It enables ARCH_HAVE_RESET and allows the user to set if, and for how long, to drive External nRST signal. It also does not contain a default board_reset, as that really should be done in the config's src if CONFIG_BOARDCTL_RESET is defined.

arch/arm/src/samv7/Kconfig

@@ -618,6 +618,28 @@ config SAMV7_ERASE_ENABLE
 
 endchoice
 
+menuconfig SAMV7_SYSTEMRESET
+	bool "Enable System Reset"
+	select ARCH_HAVE_RESET
+	---help---
+		Enable up_systemreset
+
+if SAMV7_SYSTEMRESET
+
+config SAMV7_EXTRESET_ERST
+	int "Drive External nRST duration"
+	default 0
+	range 0 16
+	---help---
+		Define if the external reset (nRST) will be generated in up_systemreset
+		and for how long:
+
+		- A value of 0 will not drive the external reset
+		- A value of 1-6 will drive the external reset for 2^SAMV7_EXTRESET_ERST
+		  slow clock cycles.
+
+endif # SAMV7_SYSTEMRESET
+
 menuconfig SAMV7_GPIO_IRQ
 	bool "GPIO pin interrupts"
 	---help---

arch/arm/src/samv7/Make.defs

@@ -150,6 +150,10 @@ ifeq ($(CONFIG_SAMV7_RSWDT),y)
 CHIP_CSRCS += sam_rswdt.c
 endif
 
+ifeq ($(CONFIG_SAMV7_SYSTEMRESET),y)
+CHIP_CSRCS += sam_systemreset.c
+endif
+
 ifeq ($(CONFIG_SAMV7_SPI_MASTER),y)
 CHIP_CSRCS += sam_spi.c
 endif

arch/arm/src/samv7/sam_systemreset.c

@@ -0,0 +1,90 @@
+/****************************************************************************
+ * arch/arm/src/samv7/sam_systemreset.c
+ *
+ *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           David Sidrane <david_s5@nscdg.com>
+ *
+ * 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 <stdint.h>
+#include <assert.h>
+
+#include <nuttx/board.h>
+#include <arch/samv7/chip.h>
+
+#include "up_arch.h"
+#include "chip/sam_rstc.h"
+
+#ifdef CONFIG_SAMV7_SYSTEMRESET
+
+/****************************************************************************
+ * Public functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_systemreset
+ *
+ * Description:
+ *   Internal reset logic.
+ *
+ ****************************************************************************/
+
+void up_systemreset(void)
+{
+  uint32_t regval;
+#if defined(CONFIG_SAMV7_EXTRESET_ERST) && CONFIG_SAMV7_EXTRESET_ERST != 0
+  uint32_t rstmr;
+#endif
+
+  regval  = (RSTC_CR_PROCRST | RSTC_CR_KEY);
+
+#if defined(CONFIG_SAMV7_EXTRESET_ERST) && CONFIG_SAMV7_EXTRESET_ERST != 0
+  regval |= RSTC_CR_EXTRST;
+
+  rstmr  = gettreg32(SAM_RSTC_MR);
+  rstmr &= ~RSTC_MR_ERSTL_MASK;
+  rstmr &= RSTC_MR_ERSTL(CONFIG_SAMV7_EXTRESET_ERST) | RSTC_MR_KEY;
+  putreg32(regval, SAM_RSTC_MR);
+#endif
+
+  putreg32(regval, SAM_RSTC_CR);
+
+  /* Wait for the reset */
+
+  for (; ; );
+}
+#endif /* CONFIG_SAMV7_SYSTEMRESET */