[PATCH 1/4] Enable a way to provide the reason for "being here"

[Juergen Beisert]

Many architectures support a way to detect why the bootloader is running.
This patch adds a global variable to be able to use the cause in some kind of
shell code to do special things on demand. For example to do an emergency boot,
when the last boot fails and the watchdog reactivate the hanging system.

Signed-off-by: Juergen Beisert <jbe at pengutronix.de>
---
 common/Kconfig         |    8 ++++++++
 common/Makefile        |    1 +
 common/reset_source.c  |   44 ++++++++++++++++++++++++++++++++++++++++++++
 include/reset_source.h |   27 +++++++++++++++++++++++++++
 4 files changed, 80 insertions(+)
 create mode 100644 common/reset_source.c
 create mode 100644 include/reset_source.h

diff --git a/common/Kconfig b/common/Kconfig
index 5fe997d..9652e5d 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -554,6 +554,14 @@ config BAREBOXENV_TARGET
 config POLLER
 	bool "generic polling infrastructure"
 
+config RESET_SOURCE
+	bool "detect Reset cause"
+	depends on GLOBALVAR
+	help
+	  Provide a global variable at runtine which reflects the possible cause
+	  of the reset and why the bootloader is currently running. It can be
+	  useful for any kind of system recovery or repair.
+
 endmenu
 
 menu "Debugging                     "
diff --git a/common/Makefile b/common/Makefile
index d99dfa2..d74dffb 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -30,6 +30,7 @@ obj-y += startup.o
 obj-y += misc.o
 obj-y += memsize.o
 obj-$(CONFIG_GLOBALVAR) += globalvar.o
+obj-$(CONFIG_RESET_SOURCE) += reset_source.o
 obj-$(CONFIG_FILETYPE) += filetype.o
 obj-y += resource.o
 obj-$(CONFIG_MENU) += menu.o
diff --git a/common/reset_source.c b/common/reset_source.c
new file mode 100644
index 0000000..2a7f9ff
--- /dev/null
+++ b/common/reset_source.c
@@ -0,0 +1,44 @@
+/*
+ * (C) Copyright 2012 Juergen Beisert - <kernel at pengutronix.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <common.h>
+#include <init.h>
+#include <environment.h>
+#include <globalvar.h>
+#include <reset_source.h>
+
+static const char * const reset_src_names[] = {
+	[RESET_UKWN] = "unknown",
+	[RESET_POR] = "POR",
+	[RESET_RST] = "RST",
+	[RESET_WDG] = "WDG",
+	[RESET_WKE] = "WKE",
+	[RESET_JTAG] = "JTAG",
+};
+
+void set_reset_source(enum reset_src_type st)
+{
+	setenv("global.system.reset", reset_src_names[st]);
+}
+EXPORT_SYMBOL(set_reset_source);
+
+/* ensure this runs after the 'global' device is already registerd */
+static int init_reset_source(void)
+{
+	globalvar_add_simple("system.reset");
+	set_reset_source(RESET_UKWN);
+	return 0;
+}
+
+coredevice_initcall(init_reset_source);
diff --git a/include/reset_source.h b/include/reset_source.h
new file mode 100644
index 0000000..6734fbde
--- /dev/null
+++ b/include/reset_source.h
@@ -0,0 +1,27 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __INCLUDE_RESET_SOURCE_H
+# define __INCLUDE_RESET_SOURCE_H
+
+enum reset_src_type {
+	RESET_UKWN,	/* maybe the SoC cannot detect the reset source */
+	RESET_POR,	/* Power On Reset (cold start) */
+	RESET_RST,	/* generic ReSeT (warm start) */
+	RESET_WDG,	/* watchdog */
+	RESET_WKE,	/* wake-up (some SoCs can handle this) */
+	RESET_JTAG,	/* JTAG reset */
+};
+
+void set_reset_source(enum reset_src_type);
+
+#endif /* __INCLUDE_RESET_SOURCE_H */
-- 
1.7.10.4