Add Kestrel SoC reboot support

soc/powerpc/CMakeLists.txt

 # SPDX-License-Identifier: Apache-2.0
 
-#if(SOC_FAMILY)
-#add_subdirectory(${SOC_FAMILY})
-#else()
-#add_subdirectory(${SOC_NAME})
-#endif()
+if(SOC_FAMILY)
+add_subdirectory(${SOC_FAMILY})
+else()
+add_subdirectory(${SOC_NAME})
+endif()

soc/powerpc/litex-kestrel/CMakeLists.txt

+#
+# Copyright (c) 2021 Raptor Engineering, LLC <sales@raptorengineering.com>
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+zephyr_sources(
+    soc.c
+)

soc/powerpc/litex-kestrel/soc.c

+/*
+ * Copyright (c) 2021 Raptor Engineering, LLC <sales@raptorengineering.com>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <kernel.h>
+#include <init.h>
+#include <device.h>
+#include <logging/log.h>
+
+#define LOG_LEVEL CONFIG_SOC_LOG_LEVEL
+LOG_MODULE_REGISTER(soc);
+
+#ifdef CONFIG_OPENPOWER_LITEX_IRQ
+extern void microwatt_irq_set_base(void *ivt_base);
+#endif
+
+// SoC base controller information
+#define SOC_CTL_BASE		DT_REG_ADDR(DT_INST(0, litex_soc_controller))
+
+// Overrides the weak PowerPC implementation
+// Reboot SoC
+void sys_arch_reboot(int type)
+{
+	// Shut down interrupts
+	irq_lock();
+
+	// Reset IRQ vector table base address
+#ifdef CONFIG_OPENPOWER_LITEX_IRQ
+	microwatt_irq_set_base(0x0);
+#endif
+
+	// Hard reboot
+	*((uint8_t*)(SOC_CTL_BASE)) = 1;
+}