Documentation/devicetree/bindings/xilinx.txt

Source file repositories/reference/linux-study-clean/Documentation/devicetree/bindings/xilinx.txt

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Linux kernel
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Documentation/devicetree/bindings/xilinx.txt
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.txt
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Support Tooling And Documentation
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Documentation
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Support Tooling And Documentation: documentation
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Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

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d) Xilinx IP cores

   The Xilinx EDK toolchain ships with a set of IP cores (devices) for use
   in Xilinx Spartan and Virtex FPGAs.  The devices cover the whole range
   of standard device types (network, serial, etc.) and miscellaneous
   devices (gpio, LCD, spi, etc).  Also, since these devices are
   implemented within the fpga fabric every instance of the device can be
   synthesised with different options that change the behaviour.

   Each IP-core has a set of parameters which the FPGA designer can use to
   control how the core is synthesized.  Historically, the EDK tool would
   extract the device parameters relevant to device drivers and copy them
   into an 'xparameters.h' in the form of #define symbols.  This tells the
   device drivers how the IP cores are configured, but it requires the kernel
   to be recompiled every time the FPGA bitstream is resynthesized.

   The new approach is to export the parameters into the device tree and
   generate a new device tree each time the FPGA bitstream changes.  The
   parameters which used to be exported as #defines will now become
   properties of the device node.  In general, device nodes for IP-cores
   will take the following form:

	(name): (generic-name)@(base-address) {
		compatible = "xlnx,(ip-core-name)-(HW_VER)"
			     [, (list of compatible devices), ...];
		reg = <(baseaddr) (size)>;
		interrupt-parent = <&interrupt-controller-phandle>;
		interrupts = < ... >;
		xlnx,(parameter1) = "(string-value)";
		xlnx,(parameter2) = <(int-value)>;
	};

	(generic-name):   an open firmware-style name that describes the
			generic class of device.  Preferably, this is one word, such
			as 'serial' or 'ethernet'.
	(ip-core-name):	the name of the ip block (given after the BEGIN
			directive in system.mhs).  Should be in lowercase
			and all underscores '_' converted to dashes '-'.
	(name):		is derived from the "PARAMETER INSTANCE" value.
	(parameter#):	C_* parameters from system.mhs.  The C_ prefix is
			dropped from the parameter name, the name is converted
			to lowercase and all underscore '_' characters are
			converted to dashes '-'.
	(baseaddr):	the baseaddr parameter value (often named C_BASEADDR).
	(HW_VER):	from the HW_VER parameter.
	(size):		the address range size (often C_HIGHADDR - C_BASEADDR + 1).

   Typically, the compatible list will include the exact IP core version
   followed by an older IP core version which implements the same
   interface or any other device with the same interface.

   'reg' and 'interrupts' are all optional properties.

   For example, the following block from system.mhs:

	BEGIN opb_uartlite
		PARAMETER INSTANCE = opb_uartlite_0
		PARAMETER HW_VER = 1.00.b
		PARAMETER C_BAUDRATE = 115200
		PARAMETER C_DATA_BITS = 8
		PARAMETER C_ODD_PARITY = 0
		PARAMETER C_USE_PARITY = 0
		PARAMETER C_CLK_FREQ = 50000000
		PARAMETER C_BASEADDR = 0xEC100000
		PARAMETER C_HIGHADDR = 0xEC10FFFF
		BUS_INTERFACE SOPB = opb_7
		PORT OPB_Clk = CLK_50MHz
		PORT Interrupt = opb_uartlite_0_Interrupt
		PORT RX = opb_uartlite_0_RX
		PORT TX = opb_uartlite_0_TX

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