reset: Add a reset controller driver for the Lantiq XWAY based SoCs

The reset controllers (on xRX200 and newer SoCs have two of them) are
provided by the RCU module. This was initially implemented as a simple
reset controller. However, the RCU module provides more functionality
(ethernet GPHYs, USB PHY, etc.), which makes it a MFD device.
The old reset controller driver implementation from
arch/mips/lantiq/xway/reset.c did not honor this fact.

For some devices the request and the status bits are different.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Cc: john@phrozen.org
Cc: kishon@ti.com
Cc: mark.rutland@arm.com
Cc: linux-mips@linux-mips.org
Cc: linux-mtd@lists.infradead.org
Cc: linux-watchdog@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: linux-spi@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/17125/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 30 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/reset/lantiq,reset.txt b/Documentation/devicetree/bindings/reset/lantiq,reset.txt
new file mode 100644
index 0000000000000..c6aef36b7d150
--- /dev/null
+++ b/Documentation/devicetree/bindings/reset/lantiq,reset.txt
@@ -0,0 +1,30 @@
+Lantiq XWAY SoC RCU reset controller binding
+============================================
+
+This binding describes a reset-controller found on the RCU module on Lantiq
+XWAY SoCs.
+
+This node has to be a sub node of the Lantiq RCU block.
+
+-------------------------------------------------------------------------------
+Required properties:
+- compatible		: Should be one of
+				"lantiq,danube-reset"
+				"lantiq,xrx200-reset"
+- reg			: Defines the following sets of registers in the parent
+			  syscon device
+			- Offset of the reset set register
+			- Offset of the reset status register
+- #reset-cells		: Specifies the number of cells needed to encode the
+			  reset line, should be 2.
+			  The first cell takes the reset set bit and the
+			  second cell takes the status bit.
+
+-------------------------------------------------------------------------------
+Example for the reset-controllers on the xRX200 SoCs:
+	reset0: reset-controller@10 {
+		compatible = "lantiq,xrx200-reset";
+		reg <0x10 0x04>, <0x14 0x04>;
+
+		#reset-cells = <2>;
+	};