[PATCHv2 1/3] mpc52xx/wdt: OF property to enable the WDT on boot

["Albrecht Dreß" <albrecht.dress@arcor.de>]

Add the "fsl,wdt-on-boot" OF property as to reserve a GPT as WDT which may
be a requirement in safety-related (e.g. ISO/EN 61508) applications.

Signed-off-by: Albrecht Dre=DF <albrecht.dress@arcor.de>

---

Change against v1: rename the new property.

 Documentation/powerpc/dts-bindings/fsl/mpc5200.txt |   17 ++++++++++++++++=
-
 1 files changed, 16 insertions(+), 1 deletions(-)

diff --git a/Documentation/powerpc/dts-bindings/fsl/mpc5200.txt b/Documenta=
tion/powerpc/dts-bindings/fsl/mpc5200.txt
index 8447fd7..ddd5ee3 100644
--- a/Documentation/powerpc/dts-bindings/fsl/mpc5200.txt
+++ b/Documentation/powerpc/dts-bindings/fsl/mpc5200.txt
@@ -103,7 +103,22 @@ fsl,mpc5200-gpt nodes
 ---------------------
 On the mpc5200 and 5200b, GPT0 has a watchdog timer function.  If the boar=
d
 design supports the internal wdt, then the device node for GPT0 should
-include the empty property 'fsl,has-wdt'.
+include the empty property 'fsl,has-wdt'.  Note that this does not activat=
e
+the watchdog.  The timer will function as a GPT if the timer api is used, =
and
+it will function as watchdog if the watchdog device is used.  The watchdog
+mode has priority over the gpt mode, i.e. if the watchdog is activated, an=
y
+gpt api call to this timer will fail with -EBUSY.
+
+If you add the property
+	fsl,wdt-on-boot =3D <n>;
+GPT0 will be marked as in-use watchdog, i.e. blocking every gpt access to =
it.
+If n>0, the watchdog is started with a timeout of n seconds.  If n=3D0, th=
e
+configuration of the watchdog is not touched.  This is useful in two cases=
:
+- just mark GPT0 as watchdog, blocking gpt accesses, and configure it late=
r;
+- do not touch a configuration assigned by the boot loader which supervise=
s
+  the boot process itself.
+
+The watchdog will respect the CONFIG_WATCHDOG_NOWAYOUT option.
=20
 An mpc5200-gpt can be used as a single line GPIO controller.  To do so,
 add the following properties to the gpt node: