ARC: reset: introduce AXS10x reset driver

ARC AXS10x boards support custom IP-block which allows to control
reset signals of selected peripherals. For example DW GMAC, etc...
This block is controlled via memory-mapped register (AKA CREG) which
represents up-to 32 reset lines. This regiter is self-clearing so we
don't need to deassert line after reset.

As of today only the following lines are used:
 - DW GMAC - line 5

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

1 files changed, 33 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/reset/snps,axs10x-reset.txt b/Documentation/devicetree/bindings/reset/snps,axs10x-reset.txt
new file mode 100644
index 000000000000..32d8435a41df
--- /dev/null
+++ b/Documentation/devicetree/bindings/reset/snps,axs10x-reset.txt
@@ -0,0 +1,33 @@
+Binding for the AXS10x reset controller
+
+This binding describes the ARC AXS10x boards custom IP-block which allows
+to control reset signals of selected peripherals. For example DW GMAC, etc...
+This block is controlled via memory-mapped register (AKA CREG) which
+represents up-to 32 reset lines.
+
+As of today only the following lines are used:
+ - DW GMAC - line 5
+
+This binding uses the common reset binding[1].
+
+[1] Documentation/devicetree/bindings/reset/reset.txt
+
+Required properties:
+- compatible: should be "snps,axs10x-reset".
+- reg: should always contain pair address - length: for creg reset
+  bits register.
+- #reset-cells: from common reset binding; Should always be set to 1.
+
+Example:
+	reset: reset-controller@11220 {
+		compatible = "snps,axs10x-reset";
+		#reset-cells = <1>;
+		reg = <0x11220 0x4>;
+	};
+
+Specifying reset lines connected to IP modules:
+	ethernet@.... {
+		....
+		resets = <&reset 5>;
+		....
+	};