ARM: STi: STiH415: Add soft reset controller support.

This patch adds soft reset controller support for STiH415 and adds new
softreset lines required for other device tree nodes in the header file.
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@st.com>

Documentation/devicetree/bindings/reset/st,sti-softreset.txt

+STMicroelectronics STi family Sysconfig Peripheral SoftReset Controller
+=============================================================================
+
+This binding describes a reset controller device that is used to enable and
+disable on-chip peripheral controllers such as USB and SATA, using
+"softreset" control bits found in the STi family SoC system configuration
+registers.
+
+The actual action taken when softreset is asserted is hardware dependent.
+However, when asserted it may not be possible to access the hardware's
+registers and after an assert/deassert sequence the hardware's previous state
+may no longer be valid.
+
+Please refer to reset.txt in this directory for common reset
+controller binding usage.
+
+Required properties:
+- compatible: Should be "st,<chip>-softreset" example:
+	"st,stih415-softreset" or "st,stih416-softreset";
+- #reset-cells: 1, see below
+
+example:
+
+	softreset: softreset-controller {
+		#reset-cells = <1>;
+		compatible = "st,stih415-softreset";
+	};
+
+
+Specifying softreset control of devices
+=======================================
+
+Device nodes should specify the reset channel required in their "resets"
+property, containing a phandle to the softreset device node and an
+index specifying which channel to use, as described in reset.txt
+
+example:
+
+	ethernet0{
+		resets			= <&softreset STIH415_ETH0_SOFTRESET>;
+	};
+
+Macro definitions for the supported reset channels can be found in:
+
+include/dt-bindings/reset-controller/stih415-resets.h
+include/dt-bindings/reset-controller/stih416-resets.h

arch/arm/boot/dts/stih415.dtsi

@@ -34,6 +34,11 @@ powerdown: powerdown-controller {
 			compatible = "st,stih415-powerdown";
 		};
 
+		softreset: softreset-controller {
+			#reset-cells = <1>;
+			compatible = "st,stih415-softreset";
+		};
+
 		syscfg_sbc: sbc-syscfg@fe600000{
 			compatible      = "st,stih415-sbc-syscfg", "syscon";
 			reg		= <0xfe600000 0xb4>;

include/dt-bindings/reset-controller/stih415-resets.h

@@ -16,4 +16,11 @@
 #define STIH415_SATA1_POWERDOWN		7
 #define STIH415_PCIE_POWERDOWN		8
 
+#define STIH415_ETH0_SOFTRESET		0
+#define STIH415_ETH1_SOFTRESET		1
+#define STIH415_IRB_SOFTRESET		2
+#define STIH415_USB0_SOFTRESET		3
+#define STIH415_USB1_SOFTRESET		4
+#define STIH415_USB2_SOFTRESET		5
+
 #endif /* _DT_BINDINGS_RESET_CONTROLLER_STIH415 */