[PATCH v6 4/4] docs: add riscv-server-ref.rst

[Daniel Henrique Barboza <daniel.barboza@oss.qualcomm.com>]

Add documentation for the new riscv-server-ref board.

Signed-off-by: Daniel Henrique Barboza <daniel.barboza@oss.qualcomm.com>
---
 docs/system/riscv/riscv-server-ref.rst | 37 ++++++++++++++++++++++++++
 docs/system/target-riscv.rst           |  1 +
 2 files changed, 38 insertions(+)
 create mode 100644 docs/system/riscv/riscv-server-ref.rst

diff --git a/docs/system/riscv/riscv-server-ref.rst b/docs/system/riscv/riscv-server-ref.rst
new file mode 100644
index 0000000000..7803133b77
--- /dev/null
+++ b/docs/system/riscv/riscv-server-ref.rst
@@ -0,0 +1,37 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+RISC-V Server Platform Reference board (``riscv-server-ref``)
+=============================================================
+
+The RISC-V Server Platform specification `spec`_ defines a standardized
+set of hardware and software capabilities that portable system software,
+such as OS and hypervisors, can rely on being present in a RISC-V server
+platform.  This machine aims to emulate this specification, providing
+an environment for firmware/OS development and testing.
+
+`spec`_ is version 1.0 at the introduction of this board.  New spec versions
+might trigger a revision of the emulation itself, which will strive to always
+match the latest version available.  In case the emulation changes aren't
+backwards compatible we'll introduce a versioning scheme, probably via
+a machine property, to allow older SW to run with older spec versions.
+
+The main features included in the riscv-server-ref board are:
+
+* IOMMU platform device (riscv-iommu-sys)
+* AIA
+* PCIe AHCI
+* PCIe NIC
+* No virtio mmio bus
+* No fw_cfg device
+* No ACPI table
+* Minimal device tree nodes
+
+There are multiple ways of using this reference board, some of them being:
+
+* BIOS: u-boot-spl.bin; SD-CARD: <disk_containing_FIT>; NVME: <distro_disk>
+* BIOS: fw_dynamic.bin; KERNEL: u-boot.bin; NVME: <distro_disk>
+* BIOS: fw_dynamic.bin; KERNEL: EDK2.fd; NVME: <distro_disk>
+* BIOS: fw_dynamic.bin; KERNEL: <linux_image>; INITRD: <busybox_initrd>
+
+
+.. _spec: https://github.com/riscv-non-isa/riscv-server-platform
diff --git a/docs/system/target-riscv.rst b/docs/system/target-riscv.rst
index 3ad5d1ddaf..3f7690331b 100644
--- a/docs/system/target-riscv.rst
+++ b/docs/system/target-riscv.rst
@@ -73,6 +73,7 @@ undocumented; you can get a complete list by running
    riscv/sifive_u
    riscv/virt
    riscv/xiangshan-kunminghu
+   riscv/riscv-server-ref
 
 RISC-V CPU firmware
 -------------------
-- 
2.43.0