ARM: 7828/1: ARMv7-M: implement restart routine common to all v7-M machines

The newly introduced function is to be used as .restart callback for
ARMv7-M machines. The used register is architecturally defined, so it
should work for all M-class machines.

Acked-by: Jonathan Austin <jonathan.austin@arm.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 32 insertions, 1 deletions

diff --git a/arch/arm/include/asm/v7m.h b/arch/arm/include/asm/v7m.h
index fa88d09fa3d9..615781c61627 100644
--- a/arch/arm/include/asm/v7m.h
+++ b/arch/arm/include/asm/v7m.h
@@ -15,6 +15,10 @@
 
 #define V7M_SCB_VTOR                    0x08
 
+#define V7M_SCB_AIRCR                   0x0c
+#define V7M_SCB_AIRCR_VECTKEY                   (0x05fa << 16)
+#define V7M_SCB_AIRCR_SYSRESETREQ               (1 << 2)
+
 #define V7M_SCB_SCR                     0x10
 #define V7M_SCB_SCR_SLEEPDEEP                   (1 << 2)
 
@@ -42,3 +46,11 @@
  */
 #define EXC_RET_STACK_MASK                      0x00000004
 #define EXC_RET_THREADMODE_PROCESSSTACK         0xfffffffd
+
+#ifndef __ASSEMBLY__
+
+enum reboot_mode;
+
+void armv7m_restart(enum reboot_mode mode, const char *cmd);
+
+#endif /* __ASSEMBLY__ */
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 86d10dd47dc4..5140df5f23aa 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -24,7 +24,7 @@ obj-$(CONFIG_ATAGS_PROC)	+= atags_proc.o
 obj-$(CONFIG_DEPRECATED_PARAM_STRUCT) += atags_compat.o
 
 ifeq ($(CONFIG_CPU_V7M),y)
-obj-y           += entry-v7m.o
+obj-y           += entry-v7m.o v7m.o
 else
 obj-y           += entry-armv.o
 endif
diff --git a/arch/arm/kernel/v7m.c b/arch/arm/kernel/v7m.c
new file mode 100644
index 000000000000..4d2cba94f5cc
--- /dev/null
+++ b/arch/arm/kernel/v7m.c
@@ -0,0 +1,19 @@
+/*
+ * Copyright (C) 2013 Uwe Kleine-Koenig for Pengutronix
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation.
+ */
+#include <linux/io.h>
+#include <linux/reboot.h>
+#include <asm/barrier.h>
+#include <asm/v7m.h>
+
+void armv7m_restart(enum reboot_mode mode, const char *cmd)
+{
+        dsb();
+        __raw_writel(V7M_SCB_AIRCR_VECTKEY | V7M_SCB_AIRCR_SYSRESETREQ,
+                        BASEADDR_V7M_SCB + V7M_SCB_AIRCR);
+        dsb();
+}