nios2: convert nios2 cpu to driver model

Convert nios2 cpu to driver model. The cpu parameters are
extracted from device tree and saved to global data structure.
We will use them to replace the custom_fpga.h .

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/doc/device-tree-bindings/cpu/nios2.txt b/doc/device-tree-bindings/cpu/nios2.txt
new file mode 100644
index 0000000..0ed2f44
--- /dev/null
+++ b/doc/device-tree-bindings/cpu/nios2.txt
@@ -0,0 +1,54 @@
+* Nios II Processor Binding
+
+This binding specifies what properties available in the device tree
+representation of a Nios II Processor Core.
+
+Users can use sopc2dts tool for generating device tree sources (dts) from a
+Qsys system. See more detail in: http://www.alterawiki.com/wiki/Sopc2dts
+
+Required properties:
+
+- compatible: Compatible property value should be "altr,nios2-1.0" or
+  "altr,nios2-1.1".
+- reg: Contains CPU index.
+- clock-frequency: Contains the clock frequency for CPU, in Hz.
+- dcache-line-size: Contains data cache line size.
+- icache-line-size: Contains instruction line size.
+- dcache-size: Contains data cache size.
+- icache-size: Contains instruction cache size.
+- altr,reset-addr: Specifies CPU reset address
+- altr,exception-addr: Specifies CPU exception address
+
+Optional properties:
+- altr,has-initda: Specifies CPU support initda instruction, should be 1.
+- altr,has-mmu: Specifies CPU support MMU support.
+- altr,has-mul: Specifies CPU hardware multipy support.
+- altr,has-div: Specifies CPU hardware divide support
+- altr,implementation: Nios II core implementation, this should be "fast";
+
+Example:
+
+cpu@0x0 {
+	device_type = "cpu";
+	compatible = "altr,nios2-1.0";
+	reg = <0>;
+	interrupt-controller;
+	#interrupt-cells = <1>;
+	clock-frequency = <125000000>;
+	dcache-line-size = <32>;
+	icache-line-size = <32>;
+	dcache-size = <32768>;
+	icache-size = <32768>;
+	altr,implementation = "fast";
+	altr,pid-num-bits = <8>;
+	altr,tlb-num-ways = <16>;
+	altr,tlb-num-entries = <128>;
+	altr,tlb-ptr-sz = <7>;
+	altr,has-div = <1>;
+	altr,has-mul = <1>;
+	altr,reset-addr = <0xc2800000>;
+	altr,fast-tlb-miss-addr = <0xc7fff400>;
+	altr,exception-addr = <0xd0000020>;
+	altr,has-initda = <1>;
+	altr,has-mmu = <1>;
+};