Hi Lee,

On Wed, 17 Sep 2014 09:34:05 -0700
Lee Jones [off-list ref] wrote:

On Thu, 11 Sep 2014, Boris BREZILLON wrote:

quoted

The GPBR block provides a set of battery-backed registers that can be used
to save data which need to be kept when the system is powered down and
VDD-core is maintained by an external battery.

A typical usage is the RTT block (when used as an RTC) which needs one of
those registers to save the current time.

Signed-off-by: Boris BREZILLON <redacted>
---
 Documentation/devicetree/bindings/mfd/atmel,gpbr.txt | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mfd/atmel,gpbr.txt

diff --git a/Documentation/devicetree/bindings/mfd/atmel,gpbr.txt b/Documentation/devicetree/bindings/mfd/atmel,gpbr.txt
new file mode 100644
index 0000000..a285695
--- /dev/null
+++ b/Documentation/devicetree/bindings/mfd/atmel,gpbr.txt

@@ -0,0 +1,15 @@
+* Device tree bindings for Atmel GPBR (General Purpose Backup Registers)
+
+The GPBR are a set of battery-backed registers.
+
+Required properties:
+- compatible:		"atmel,at91sam9260-gpbr", "syscon"
+- reg:			contains offset/length value of the GPBR memory
+			region.
+
+Example:
+
+gpbr: gpbr at fffffd50 {

Is something referencing this node via phandle?  If not, please remove
the label.

Yes, the rtt device is referencing it in its atmel,rtt-rtc-time-reg
property (see patch 8 of this series).

Best Regards,

Boris

-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com