reset_source: Add external reset ...

Some SoCs have special device pins for external reset signals.

Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

reset_source: make safe to call earlier ...

reset_source_init used to set the reset source to unknown in a
coredevice_initcall. This means if reset_source_set() has been called
earlier the value would have been overwritten. Fix this by calling
globalvar_add_simple() each time reset_source_set() is called.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

reset_source: add thermal reset ...

Some SoCs are able to detect if they got reset
in response to an overtemperature event.

Signed-off-by: Lucas Stach <dev@lynxeye.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

reset_source: add reset_source_get ...

To get reset_source from C code, not only from shell.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

reset_source: rename set_reset_source to reset_source_set ...

To get all reset source related functions into the same function
namespace.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

globalvar: Allow to set initial value ...

Calling globalvar_add_simple() and setting a value is more than common.
Add a parameter for the initial value.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Enable a way to provide the reason for "being here" ...

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@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>