docs: move openrisc documentation under Documentation/arch/

Architecture-specific documentation is being moved into Documentation/arch/
as a way of cleaning up the top-level documentation directory and making
the docs hierarchy more closely match the source hierarchy.  Move
Documentation/openrisc into arch/ and fix all in-tree references.

Cc: Jonas Bonn <jonas@southpole.se>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Stafford Horne <shorne@gmail.com>
Acked-by: Alex Shi <alexs@kernel.org>
Reviewed-by: Yanteng Si <siyanteng@loongson.cn>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

5 files changed, 160 insertions, 1 deletions

diff --git a/Documentation/arch/index.rst b/Documentation/arch/index.rst
index 792f58e30f253f..65945daa40fe98 100644
--- a/Documentation/arch/index.rst
+++ b/Documentation/arch/index.rst
@@ -17,7 +17,7 @@ implementation.
    ../m68k/index
    ../mips/index
    ../nios2/index
-   ../openrisc/index
+   openrisc/index
    ../parisc/index
    ../powerpc/index
    ../riscv/index
diff --git a/Documentation/arch/openrisc/features.rst b/Documentation/arch/openrisc/features.rst
new file mode 100644
index 00000000000000..3f7c40d219f2cc
--- /dev/null
+++ b/Documentation/arch/openrisc/features.rst
@@ -0,0 +1,3 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. kernel-feat:: $srctree/Documentation/features openrisc
diff --git a/Documentation/arch/openrisc/index.rst b/Documentation/arch/openrisc/index.rst
new file mode 100644
index 00000000000000..6879f998b87a3b
--- /dev/null
+++ b/Documentation/arch/openrisc/index.rst
@@ -0,0 +1,20 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=====================
+OpenRISC Architecture
+=====================
+
+.. toctree::
+   :maxdepth: 2
+
+   openrisc_port
+   todo
+
+   features
+
+.. only::  subproject and html
+
+   Indices
+   =======
+
+   * :ref:`genindex`
diff --git a/Documentation/arch/openrisc/openrisc_port.rst b/Documentation/arch/openrisc/openrisc_port.rst
new file mode 100644
index 00000000000000..657ac4af7be6ab
--- /dev/null
+++ b/Documentation/arch/openrisc/openrisc_port.rst
@@ -0,0 +1,121 @@
+==============
+OpenRISC Linux
+==============
+
+This is a port of Linux to the OpenRISC class of microprocessors; the initial
+target architecture, specifically, is the 32-bit OpenRISC 1000 family (or1k).
+
+For information about OpenRISC processors and ongoing development:
+
+	=======		=============================
+	website		https://openrisc.io
+	email		openrisc@lists.librecores.org
+	=======		=============================
+
+---------------------------------------------------------------------
+
+Build instructions for OpenRISC toolchain and Linux
+===================================================
+
+In order to build and run Linux for OpenRISC, you'll need at least a basic
+toolchain and, perhaps, the architectural simulator.  Steps to get these bits
+in place are outlined here.
+
+1) Toolchain
+
+Toolchain binaries can be obtained from openrisc.io or our github releases page.
+Instructions for building the different toolchains can be found on openrisc.io
+or Stafford's toolchain build and release scripts.
+
+	==========	=================================================
+	binaries	https://github.com/openrisc/or1k-gcc/releases
+	toolchains	https://openrisc.io/software
+	building	https://github.com/stffrdhrn/or1k-toolchain-build
+	==========	=================================================
+
+2) Building
+
+Build the Linux kernel as usual::
+
+	make ARCH=openrisc CROSS_COMPILE="or1k-linux-" defconfig
+	make ARCH=openrisc CROSS_COMPILE="or1k-linux-"
+
+3) Running on FPGA (optional)
+
+The OpenRISC community typically uses FuseSoC to manage building and programming
+an SoC into an FPGA.  The below is an example of programming a De0 Nano
+development board with the OpenRISC SoC.  During the build FPGA RTL is code
+downloaded from the FuseSoC IP cores repository and built using the FPGA vendor
+tools.  Binaries are loaded onto the board with openocd.
+
+::
+
+	git clone https://github.com/olofk/fusesoc
+	cd fusesoc
+	sudo pip install -e .
+
+	fusesoc init
+	fusesoc build de0_nano
+	fusesoc pgm de0_nano
+
+	openocd -f interface/altera-usb-blaster.cfg \
+		-f board/or1k_generic.cfg
+
+	telnet localhost 4444
+	> init
+	> halt; load_image vmlinux ; reset
+
+4) Running on a Simulator (optional)
+
+QEMU is a processor emulator which we recommend for simulating the OpenRISC
+platform.  Please follow the OpenRISC instructions on the QEMU website to get
+Linux running on QEMU.  You can build QEMU yourself, but your Linux distribution
+likely provides binary packages to support OpenRISC.
+
+	=============	======================================================
+	qemu openrisc	https://wiki.qemu.org/Documentation/Platforms/OpenRISC
+	=============	======================================================
+
+---------------------------------------------------------------------
+
+Terminology
+===========
+
+In the code, the following particles are used on symbols to limit the scope
+to more or less specific processor implementations:
+
+========= =======================================
+openrisc: the OpenRISC class of processors
+or1k:     the OpenRISC 1000 family of processors
+or1200:   the OpenRISC 1200 processor
+========= =======================================
+
+---------------------------------------------------------------------
+
+History
+========
+
+18-11-2003	Matjaz Breskvar (phoenix@bsemi.com)
+	initial port of linux to OpenRISC/or32 architecture.
+        all the core stuff is implemented and seams usable.
+
+08-12-2003	Matjaz Breskvar (phoenix@bsemi.com)
+	complete change of TLB miss handling.
+	rewrite of exceptions handling.
+	fully functional sash-3.6 in default initrd.
+	a much improved version with changes all around.
+
+10-04-2004	Matjaz Breskvar (phoenix@bsemi.com)
+	alot of bugfixes all over.
+	ethernet support, functional http and telnet servers.
+	running many standard linux apps.
+
+26-06-2004	Matjaz Breskvar (phoenix@bsemi.com)
+	port to 2.6.x
+
+30-11-2004	Matjaz Breskvar (phoenix@bsemi.com)
+	lots of bugfixes and enhancments.
+	added opencores framebuffer driver.
+
+09-10-2010    Jonas Bonn (jonas@southpole.se)
+	major rewrite to bring up to par with upstream Linux 2.6.36
diff --git a/Documentation/arch/openrisc/todo.rst b/Documentation/arch/openrisc/todo.rst
new file mode 100644
index 00000000000000..420b18b87eda00
--- /dev/null
+++ b/Documentation/arch/openrisc/todo.rst
@@ -0,0 +1,15 @@
+====
+TODO
+====
+
+The OpenRISC Linux port is fully functional and has been tracking upstream
+since 2.6.35.  There are, however, remaining items to be completed within
+the coming months.  Here's a list of known-to-be-less-than-stellar items
+that are due for investigation shortly, i.e. our TODO list:
+
+-  Implement the rest of the DMA API... dma_map_sg, etc.
+
+-  Finish the renaming cleanup... there are references to or32 in the code
+   which was an older name for the architecture.  The name we've settled on is
+   or1k and this change is slowly trickling through the stack.  For the time
+   being, or32 is equivalent to or1k.