ARM: AT91: Add DT support to AT91RM9200 System Timer

Based on AT91 PIT DT patch from Jean-Christophe PLAGNIOL-VILLARD.

Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/Documentation/devicetree/bindings/arm/atmel-at91.txt b/Documentation/devicetree/bindings/arm/atmel-at91.txt
index ecc81e3..8adc9a8 100644
--- a/Documentation/devicetree/bindings/arm/atmel-at91.txt
+++ b/Documentation/devicetree/bindings/arm/atmel-at91.txt
@@ -7,6 +7,12 @@
 - interrupts: Should contain interrupt for the PIT which is the IRQ line
   shared across all System Controller members.
 
+System Timer (ST) required properties:
+- compatible: Should be "atmel,at91rm9200-st"
+- reg: Should contain registers location and length
+- interrupts: Should contain interrupt for the ST which is the IRQ line
+  shared across all System Controller members.
+
 TC/TCLIB Timer required properties:
 - compatible: Should be "atmel,<chip>-pit".
   <chip> can be "at91rm9200" or "at91sam9x5"