[PATCH 2/2] docs/system: riscv: Add documentation for 'microchip-icicle-kit' machine

[Bin Meng <bmeng.cn@gmail.com>]

From: Bin Meng <bin.meng@windriver.com>

This adds the documentation to describe what is supported for the
'microchip-icicle-kit' machine, and how to boot the machine in QEMU.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
---

 docs/system/riscv/microchip-icicle-kit.rst | 89 ++++++++++++++++++++++
 docs/system/target-riscv.rst               |  1 +
 2 files changed, 90 insertions(+)
 create mode 100644 docs/system/riscv/microchip-icicle-kit.rst

diff --git a/docs/system/riscv/microchip-icicle-kit.rst b/docs/system/riscv/microchip-icicle-kit.rst
new file mode 100644
index 0000000000..4fe97bce3f
--- /dev/null
+++ b/docs/system/riscv/microchip-icicle-kit.rst
@@ -0,0 +1,89 @@
+Microchip PolarFire SoC Icicle Kit (``microchip-icicle-kit``)
+=============================================================
+
+Microchip PolarFire SoC Icicle Kit integrates a PolarFire SoC, with one
+SiFive's E51 plus four U54 cores and many on-chip peripherals and an FPGA.
+
+For more details about Microchip PolarFire SoC, please see:
+https://www.microsemi.com/product-directory/soc-fpgas/5498-polarfire-soc-fpga
+
+The Icicle Kit board information can be found here:
+https://www.microsemi.com/existing-parts/parts/152514
+
+Supported devices
+-----------------
+
+The ``microchip-icicle-kit`` machine supports the following devices:
+
+ * 1 E51 core
+ * 4 U54 cores
+ * Core Level Interruptor (CLINT)
+ * Platform-Level Interrupt Controller (PLIC)
+ * L2 Loosely Integrated Memory (L2-LIM)
+ * DDR memory controller
+ * 5 MMUARTs
+ * 1 DMA controller
+ * 2 GEM Ethernet controllers
+ * 1 SDHC storage controller
+
+Boot options
+------------
+
+The ``microchip-icicle-kit`` machine can start using the standard -bios
+functionality for loading its BIOS image, aka Hart Software Services (HSS_).
+HSS loads the second stage bootloader U-Boot from an SD card. It does not
+support direct kernel loading via the -kernel option. One has to load kernel
+from U-Boot.
+
+The memory is set to 1537 MiB by default which is the minimum required high
+memory size by HSS. A sanity check on ram size is performed in the machine
+init routine to prompt user to increase the RAM size to > 1537 MiB when less
+than 1537 MiB ram is detected.
+
+Boot the machine
+----------------
+
+HSS 2020.12 release is tested at the time of writing. To build an HSS image
+that can be booted by the ``microchip-icicle-kit`` machine, type the following
+in the HSS source tree:
+
+.. code-block:: bash
+
+  $ export CROSS_COMPILE=riscv64-linux-
+  $ cp boards/mpfs-icicle-kit-es/def_config .config
+  $ make BOARD=mpfs-icicle-kit-es
+
+Download the official SD card image released by Microchip and prepare it for
+QEMU usage:
+
+.. code-block:: bash
+
+  $ wget ftp://ftpsoc.microsemi.com/outgoing/core-image-minimal-dev-icicle-kit-es-sd-20201009141623.rootfs.wic.gz
+  $ gunzip core-image-minimal-dev-icicle-kit-es-sd-20201009141623.rootfs.wic.gz
+  $ qemu-img resize core-image-minimal-dev-icicle-kit-es-sd-20201009141623.rootfs.wic 4G
+
+Then we can boot the machine by:
+
+.. code-block:: bash
+
+  $ qemu-system-riscv64 -M microchip-icicle-kit -smp 5 \
+      -bios path/to/hss.bin -sd path/to/sdcard.img \
+      -nic user,model=cadence_gem \
+      -nic tap,ifname=tap,model=cadence_gem,script=no \
+      -display none -serial stdio \
+      -chardev socket,id=serial1,path=serial1.sock,server=on,wait=on \
+      -serial chardev:serial1
+
+With above command line, current terminal session will be used for the first
+serial port. Open another terminal window, and use `minicom` to connect the
+second serial port.
+
+.. code-block:: bash
+
+  $ minicom -D unix\#serial1.sock
+
+HSS output is on the first serial port (stdio) and U-Boot outputs on the
+second serial port. U-Boot will automatically load the Linux kernel from
+the SD card image.
+
+.. _HSS: https://github.com/polarfire-soc/hart-software-services
diff --git a/docs/system/target-riscv.rst b/docs/system/target-riscv.rst
index 94d99c4c82..8d5946fbbb 100644
--- a/docs/system/target-riscv.rst
+++ b/docs/system/target-riscv.rst
@@ -66,6 +66,7 @@ undocumented; you can get a complete list by running
 .. toctree::
    :maxdepth: 1
 
+   riscv/microchip-icicle-kit
    riscv/sifive_u
 
 RISC-V CPU features
-- 
2.25.1