dt-bindings: Add devicetree bindings

Add snapshot of device tree bindings from keystone common kernel, branch
"android-mainline-keystone-qcom-release" at c4c12103f9c0 ("Snap for 9228065
from e32903b9a63bb558df8b803b076619c53c16baad to
android-mainline-keystone-qcom-release").

Change-Id: I7682079615cbd9f29340a5c1f2a1d84ec441a1f1
Signed-off-by: Melody Olvera <quic_molvera@quicinc.com>

bindings/mips/img/pistachio-marduk.txt

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+Imagination Technologies' Pistachio SoC based Marduk Board
+==========================================================
+
+Compatible string must be "img,pistachio-marduk", "img,pistachio"
+
+Hardware and other related documentation is available at
+https://docs.creatordev.io/ci40/
+
+It is also known as Creator Ci40. Marduk is legacy name and will
+be there for decades.

bindings/mips/img/pistachio.txt

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+Imagination Pistachio SoC
+=========================
+
+Required properties:
+--------------------
+ - compatible: Must include "img,pistachio".
+
+CPU nodes:
+----------
+A "cpus" node is required.  Required properties:
+ - #address-cells: Must be 1.
+ - #size-cells: Must be 0.
+A CPU sub-node is also required for at least CPU 0.  Since the topology may
+be probed via CPS, it is not necessary to specify secondary CPUs.  Required
+propertis:
+ - device_type: Must be "cpu".
+ - compatible: Must be "mti,interaptiv".
+ - reg: CPU number.
+ - clocks: Must include the CPU clock.  See ../../clock/clock-bindings.txt for
+   details on clock bindings.
+Example:
+	cpus {
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		cpu0: cpu@0 {
+			device_type = "cpu";
+			compatible = "mti,interaptiv";
+			reg = <0>;
+			clocks = <&clk_core CLK_MIPS>;
+		};
+	};
+
+
+Boot protocol:
+--------------
+In accordance with the MIPS UHI specification[1], the bootloader must pass the
+following arguments to the kernel:
+ - $a0: -2.
+ - $a1: KSEG0 address of the flattened device-tree blob.
+
+[1] http://prplfoundation.org/wiki/MIPS_documentation

bindings/mips/img/xilfpga.txt

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+Imagination University Program MIPSfpga
+=======================================
+
+Under the Imagination University Program, a microAptiv UP core has been
+released for academic usage.
+
+As we are dealing with a MIPS core instantiated on an FPGA, specifications
+are fluid and can be varied in RTL.
+
+This binding document is provided as baseline guidance for the example
+project provided by IMG.
+
+The example project runs on the Nexys4DDR board by Digilent powered by
+the ARTIX-7 FPGA by Xilinx.
+
+Relevant details about the example project and the Nexys4DDR board:
+
+- microAptiv UP core m14Kc
+- 50MHz clock speed
+- 128Mbyte DDR RAM	at 0x0000_0000
+- 8Kbyte RAM		at 0x1000_0000
+- axi_intc		at 0x1020_0000
+- axi_uart16550		at 0x1040_0000
+- axi_gpio		at 0x1060_0000
+- axi_i2c		at 0x10A0_0000
+- custom_gpio		at 0x10C0_0000
+- axi_ethernetlite	at 0x10E0_0000
+- 8Kbyte BootRAM	at 0x1FC0_0000
+
+Required properties:
+--------------------
+ - compatible: Must include "digilent,nexys4ddr","img,xilfpga".
+
+CPU nodes:
+----------
+A "cpus" node is required.  Required properties:
+ - #address-cells: Must be 1.
+ - #size-cells: Must be 0.
+A CPU sub-node is also required for at least CPU 0. Required properties:
+ - device_type: Must be "cpu".
+ - compatible: Must be "mips,m14Kc".
+ - reg: Must be <0>.
+ - clocks: phandle to ext clock for fixed-clock received by MIPS core.
+
+Example:
+
+	compatible = "img,xilfpga","digilent,nexys4ddr";
+	cpus {
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		cpu0: cpu@0 {
+			device_type = "cpu";
+			compatible = "mips,m14Kc";
+			reg = <0>;
+			clocks	= <&ext>;
+		};
+	};
+
+	ext: ext {
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <50000000>;
+	};
+
+Boot protocol:
+--------------
+
+The BootRAM is a writeable "RAM" in FPGA at 0x1FC0_0000.
+This is for easy reprogrammibility via JTAG.
+
+The BootRAM initializes the cache and the axi_uart peripheral.
+
+DDR initialization is already handled by a HW IP block.
+
+When the example project bitstream is loaded, the cpu_reset button
+needs to be pressed.
+
+The bootram initializes the cache and axi_uart.
+Then outputs MIPSFPGA\n\r on the serial port on the Nexys4DDR board.
+
+At this point, the board is ready to load the Linux kernel
+vmlinux file via JTAG.