[PATCH] ARM: ARMv7-M: implement restart routine common to all v7-M machines

[Uwe Kleine-König]

On Wed, Aug 14, 2013 at 05:44:01PM +0100, Jonathan Austin wrote:
> On 14/08/13 16:37, Uwe Kleine-König wrote:
> >Signed-off-by: Uwe Kleine-König <u.kleine-koenig at pengutronix.de>
> 
> Do we get a commit message? ;)
You did see the Subject line? I guess you did and it's not enough to
understand it. The new function is used as .restart member of
{DT_,}MACHINE_START.

> 
> >---
> >  arch/arm/include/asm/v7m.h   | 12 ++++++++++++
> >  arch/arm/kernel/Makefile     |  2 +-
> >  arch/arm/kernel/common-v7m.c | 19 +++++++++++++++++++
> >  3 files changed, 32 insertions(+), 1 deletion(-)
> >  create mode 100644 arch/arm/kernel/common-v7m.c
> >
> >diff --git a/arch/arm/include/asm/v7m.h b/arch/arm/include/asm/v7m.h
> >index fa88d09..615781c 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)
> >+
> 
> These all look good, happy with the names too.
> >  #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;
> 
> Certainly worth introducing what the plans for this are in the long
> run - but I suspect the commit message might have contained that
> info?
> 
> >+
> >+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 86d10dd..688b8be 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 common-v7m.o
> >  else
> >  obj-y		+= entry-armv.o
> >  endif
> >diff --git a/arch/arm/kernel/common-v7m.c b/arch/arm/kernel/common-v7m.c
> >new file mode 100644
> >index 0000000..4d2cba9
> >--- /dev/null
> >+++ b/arch/arm/kernel/common-v7m.c
> 
> Is this really the right place for such a function? My immediate
> thought is that such a thing belongs in proc-v7m.S
> 
> Is this fitting in to a an existing framework or pattern that I'm missing?
proc-v7m.S doesn't work as my function is coded in C :-)

Here are some other restart functions with the file they are defined in:

davinci_restart   | arch/arm/mach-davinci/devices.c
exynos4_restart   | arch/arm/mach-exynos/common.c
highbank_restart  | arch/arm/mach-highbank/system.c
mxc_restart       | arch/arm/mach-imx/system.c
omap3xxx_restart  | arch/arm/mach-omap2/omap3-restart.c
pxa_restart       | arch/arm/mach-pxa/reset.c
versatile_restart | arch/arm/mach-versatile/core.c

at91 doesn't seem to have a restart function.

Hmm, I'm still happy with arch/arm/kernel/common-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();
> >+}

Best regards
Uwe

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