path: root/user/bsps/bsps-riscv.rst

.. SPDX-License-Identifier: CC-BY-SA-4.0

.. Copyright (C) 2018 embedded brains GmbH & Co. KG

riscv (RISC-V)
**************

riscv
=====

**Each variant in this first group corresponds to a GCC multilib option with
different RISC-V standard extensions.**

* rv32i

* rv32iac

* rv32im

* rv32imac

* rv32imafc

* rv32imafd

* rv32imafdc

* rv64imac

* rv64imafd

* rv64imafdc

Each variant reflects an ISA with ABI and code model choice. All rv64 BSPs have
medany code model by default, while rv32 BSPs are medlow. The reason is that
RV32 medlow can access the entire 32-bit address space, while RV64 medlow can
only access addresses below 0x80000000. With RV64 medany, it's possible to
perform accesses above 0x80000000. The BSP must be started in machine mode.

The reference platforms for the rv* variants include the QEMU `virt` and
`spike` machines and the Spike RISC-V ISA simulator.

**The BSP also provides the following variants for specific hardware targets:**

* frdme310arty - The reference platform for this variant is the Arty FPGA board
  with the SiFive Freedom E310 reference design.

* mpfs64imafdc - The reference platform for this variant is the Microchip
  PolarFire SoC Icicle Kit.

* kendrytek210 - The reference platform for this variant is the Kendryte K210
  SoC on the Sipeed MAiX BiT or Maixduino board.


Build Configuration Options
---------------------------

The following options can be used in the BSP section of the ``waf``
configuration INI file. The ``waf`` defaults can be used to inspect the values.

``BSP_PRESS_KEY_FOR_RESET``
    If defined to a non-zero value, then print a message and wait until pressed
    before resetting board when application terminates.

``BSP_RESET_BOARD_AT_EXIT``
    If defined to a non-zero value, then reset the board when the application
    terminates.

``BSP_PRINT_EXCEPTION_CONTEXT``
    If defined to a non-zero value, then print the exception context when an
    unexpected exception occurs.

``BSP_FDT_BLOB_SIZE_MAX``
    The maximum size of the device tree blob in bytes (default is 65536).

``BSP_DTB_IS_SUPPORTED``
    If defined to a non-zero value, then the device tree blob is embedded in
    the BSP.

``BSP_DTB_HEADER_PATH``
    The path to the header file containing the device tree blob.

``BSP_CONSOLE_BAUD``
    The default baud for console driver devices (default is 115200).

``RISCV_MAXIMUM_EXTERNAL_INTERRUPTS``
     The maximum number of external interrupts supported by the BSP (default
     is 64).

``RISCV_ENABLE_HTIF_SUPPORT``
     Enable the Host/Target Interface (HTIF) support (enabled by default).

``RISCV_CONSOLE_MAX_NS16550_DEVICES``
     The maximum number of NS16550 devices supported by the console driver
     (default is 2).

``RISCV_ENABLE_SIFIVE_UART_SUPPORT``
     Enable the SiFive console UART (disabled by default).

``RISCV_RAM_REGION_BEGIN``
     The begin of the RAM region for linker command file
     (default is 0x80000000).

``RISCV_RAM_REGION_SIZE``
     The size of the RAM region for linker command file (default 64MiB).

``RISCV_ENABLE_FRDME310ARTY_SUPPORT``
     Enables support sifive Freedom E310 Arty board if defined to a non-zero
     value,otherwise it is disabled (disabled by default).

``RISCV_ENABLE_MPFS_SUPPORT``
     Enables support Microchip PolarFire SoC if defined to a non-zero
     value, otherwise it is disabled (disabled by default).

``RISCV_ENABLE_KENDRYTE_K210_SUPPORT``
     Enables support for the Kendtryte K210 SoC if defined to a non-zero
     value, otherwise it is disabled (disabled by default).

``RISCV_BOOT_HARTID``
     The boot hartid (processor number) of risc-v cpu by default 0.

Interrupt Controller
--------------------

Exactly one Core Local Interruptor (CLINT) and exactly one Platform-Level
Interrupt Controller (PLIC) are supported.  The maximum number of external
interrupts supported by the BSP is defined by the
``RISCV_MAXIMUM_EXTERNAL_INTERRUPTS`` BSP option.

Clock Driver
------------

The clock driver uses the CLINT timer.

Console Driver
--------------

The console driver supports devices compatible to:

* "ucb,htif0" (depending on the ``RISCV_ENABLE_HTIF_SUPPORT`` BSP option),

* "ns16550a" (see ``RISCV_CONSOLE_MAX_NS16550_DEVICES`` BSP option),

* "ns16750" (see ``RISCV_CONSOLE_MAX_NS16550_DEVICES`` BSP option), and

* "sifive,uart0" (see ``RISCV_ENABLE_SIFIVE_UART_SUPPORT`` BSP option).

They are initialized according to the device tree.  The console driver does not
configure the pins or peripheral clocks.  The console device is selected
according to the device tree "/chosen/stdout-path" property value.

QEMU
----

All of the BSP variants that start with rv can be run on QEMU's virt
and spike machines. For instance, to run the ``rv64imafdc`` BSP with the
following "config.ini" file.

.. code-block:: none

    [riscv/rv64imafdc]

Run the following QEMU command.

.. code-block:: shell

    $ qemu-system-riscv64 -M virt -nographic -bios $RTEMS_EXE
    $ qemu-system-riscv64 -M spike -nographic -bios $RTEMS_EXE

Spike
----

All of the BSP variants that start with rv can be run on Spike.  For instance,
to run the ``rv64imafdc`` BSP with the following "config.ini" file.

.. code-block:: none

    [riscv/rv64imafdc]

Run the following Spike command.

.. code-block:: shell

    $ spike --isa=rv64imafdc $RTEMS_EXE

Unlike QEMU, Spike supports enabling/disabling a subset of the imafdc
extensions and has support for further RISC-V extensions as well. A fault will
be triggered if an executable built with rv64imafdc RISC-V's -march option run
on Spike with --isa=rv64i option. If no --isa option is specified, the default
is rv64imafdc.

Microchip PolarFire SoC
-----------------------

The PolarFire SoC is the 4x 64-bit RISC-V U54 cores and a 64-bit RISC-V E51
monitor core SoC from the Microchip.

The ``mpfs64imafdc`` BSP variant supports the U54 cores but not the E51 because
the E51 monitor core is reserved for the first stage bootloader (Hart Software
Services). In order to boot from the first U54 core, ``RISCV_BOOT_HARTID`` is
set to 1 by default.

The device tree blob is embedded in the ``mpfs64imafdc`` BSP variant by default
with the ``BSP_DTB_IS_SUPPORTED`` enabled and the DTB header path
``BSP_DTB_HEADER_PATH`` is set to bsp/mpfs-dtb.h.

**SMP test procedure for the Microchip PolarFire Icicle Kit:**

The "config.ini" file.

.. code-block:: none

    [riscv/mpfs64imafdc]
    BUILD_TESTS = True
    RTEMS_POSIX_API=True
    RTEMS_SMP = True
    BSP_START_COPY_FDT_FROM_U_BOOT=False
    BSP_VERBOSE_FATAL_EXTENSION = False

Build RTEMS.

.. code-block:: shell

    $ ./waf configure --prefix=$HOME/rtems-start/rtems/@rtems-ver-major@
    $ ./waf

Convert .exe to .elf file.

.. code-block:: shell

    $ riscv-rtems@rtems-ver-major@-objcopy build/riscv/mpfs64imafdc/testsuites/smptests/smp01.exe build/riscv/mpfs64imafdc/testsuites/smptests/smp01.elf

Generate a payload for the `smp01.elf` using the `hss-payload-generator <https://github.com/polarfire-soc/hart-software-services/blob/master/tools/hss-payload-generator>`_.

* Copy `smp01.elf` file to the HSS/tools/hss-payload-generator/test directory.

* Go to hss-payload-generator source directory.

.. code-block:: shell

    $ cd hart-software-services/tools/hss-payload-generator

* Edit test/uboot.yaml file for the hart entry points and correct name of the
  binary file.

.. code-block:: none

    set-name: 'PolarFire-SoC-HSS::RTEMS'
    hart-entry-points: {u54_1: '0x1000000000', u54_2: '0x1000000000', u54_3: '0x1000000000', u54_4: '0x1000000000'}
    payloads:
     test/smp01.elf: {exec-addr: '0x1000000000', owner-hart: u54_1, secondary-hart: u54_2, secondary-hart: u54_3, secondary-hart: u54_4, priv-mode: prv_m, skip-opensbi: true}

* Generate payload

.. code-block:: shell

    $ ./hss-payload-generator -c test/uboot.yaml payload.bin

Once the payload binary is generated, it should be copied to the eMMC/SD.

`FPGA design with HSS programming file <https://github.com/polarfire-soc/polarfire-soc-documentation/blob/master/boards/mpfs-icicle-kit-es/updating-icicle-kit/updating-icicle-kit-design-and-linux.md>`_.

Program the eMMC/SD with the payload binary.

* Power Cycle the Microchip PolarFire Icicle Kit and stop at the HSS.

* type "mmc" and then "usbdmsc" on the HSS terminal(UART0).

* Load the payload.bin from the Host PC.

.. code-block:: shell

    $ sudo dd if=payload.bin of=/dev/sdb bs=512

Reset the Microchip PolarFire SoC Icicle Kit.

Serial terminal UART1 displays the SMP example messages

.. code-block:: none

    *** BEGIN OF TEST SMP 1 ***
    *** TEST VERSION: 6.0.0.ef33f861e16de9bf4190a36e4d18062c7300986c
    *** TEST STATE: EXPECTED_PASS
    *** TEST BUILD: RTEMS_POSIX_API RTEMS_SMP
    *** TEST TOOLS: 12.1.1 20220622 (RTEMS 6, RSB 3cb78b0b815ba05d17f5c6
		5865d246a8333aa087, Newlib ea99f21)

    CPU 3 start task TA0
    CPU 2 running Task TA0
    CPU 3 start task TA1
    CPU 1 running Task TA1
    CPU 3 start task TA2
    CPU 0 running Task TA2

    *** END OF TEST SMP 1 ***

Kendryte K210
-------------

The Kendryte K210 SoC is a dual core 64-bit RISC-V SoC with an AI NPU, built in
SRAM, and a variety of peripherals. Currently just the console UART, interrupt
controller, and timer are supported.

The device tree blob is embedded in the ``kendrytek210`` BSP variant by
default.  When the kendrytek210 BSP variant is selected,
``BSP_DTB_IS_SUPPORTED`` enabled and the DTB header path
``BSP_DTB_HEADER_PATH`` is set to ``bsp/kendryte-k210-dtb.h``.

The ``kendrytek210`` BSP variant has been tested on the following simulator and
boards:

* Renode.io simulator using the Kendrtye k210 model
* Sipeed MAiX BiT board
* Sipeed Maixduino board
* Sipeed MAiX Dock board

**Building the Kendryte K210 BSP**

Configuration file ``config.ini``:

.. code-block:: none

    [riscv/kendrytek210]
    RTEMS_SMP = True

Build RTEMS:

.. code-block:: shell

    $ ./waf configure --prefix=$HOME/rtems-start/rtems/@rtems-ver-major@
    $ ./waf

**Flash an executable to a supported K210 board**

Binary images can be flashed to the Sipeed boards through the USB port using
the ``kflash.py`` utility available from the python pip utility.

.. code-block:: shell

    $ riscv-rtems@rtems-ver-major@-objcopy -Obinary ticker.exe ticker.bin
    $ kflash.py --uart /dev/ttyUSB0 ticker.bin

After the image is flashed, the RTEMS image will automatically boot. It will
also run when the board is reset or powered through the USB cable. The USB port
provides the power and console UART. Plug the USB cable into a host PC and
bring up a terminal emulator at 115200 baud, 8 data bits, 1 stop bit, no
parity, and no flow control. On Linux the UART device is often
``/dev/ttyUSB0``.

**Run a RTEMS application on the Renode.io simulator**

RTEMS executables compiled with the kendrytek210 BSP can run on the renode.io
simulator using the built-in K210 model. The simulator currently supports the
console UART, interrupt controller, and timer.

To install renode.io please refer to the `installation instructions <https://github.com/renode/renode#installation>`_.
Once installed, save the following file as `k210_rtems.resc`.

.. code-block:: shell

   using sysbus

   $bin?=@ticker.exe

   mach create "K210"

   machine LoadPlatformDescription @platforms/cpus/kendryte_k210.repl

   showAnalyzer uart

   sysbus Tag <0x50440000 0x10000> "SYSCTL"
   sysbus Tag <0x50440018 0x4> "pll_lock" 0xFFFFFFFF
   sysbus Tag <0x5044000C 0x4> "pll1"
   sysbus Tag <0x50440008 0x4> "pll0"
   sysbus Tag <0x50440020 0x4> "clk_sel0"
   sysbus Tag <0x50440028 0x4> "clk_en_cent"
   sysbus Tag <0x5044002c 0x4> "clk_en_peri"

   macro reset
   """
      sysbus LoadELF $bin
   """
   runMacro $reset

After saving the above file in in the same directory as your RTEMS ELF images,
start renode and load the `k210_rtems.resc` script to start the emulation.

.. code-block:: shell

    (monitor) s @k210_rtems.resc

You should see a renode UART window and the RTEMS ticker example output. If you
want to run a different RTEMS image, you can edit the file or enter the
following on the renode console.

.. code-block:: shell

    (monitor) $bin=@smp08.exe
    (monitor) s @k210_rtems.resc

The above example will run the SMP08 example instead of ticker.

**Generating the Device Tree Header**

The kendrytek210 BSP uses a built in device tree blob. If additional peripheral
support is added to the BSP, the device tree may need to be updated. After
editing the device tree source, compile it to a device tree blob with the
following command:

.. code-block:: shell

    $ dtc -O dtb -b 0 -o kendryte-k210.dtb kendryte-k210.dts

The dtb file can then be converted to a C array using the rtems-bin2c tool.
The data for the device tree binary can then replace the existing device tree
binary data in the ``kendryte-k210-dtb.h`` header file.

noel
====

This BSP supports the `NOEL-V <https://gaisler.com/noel-v>`_ systems from
Cobham Gaisler. The NOEL-V is a synthesizable VHDL model of a processor that
implements the RISC-V architecture. It is part of the open source `GRLIB
<https://gaisler.com/grlib>`_ IP Library. The following BSP variants correspond
to common NOEL-V configurations:

* noel32im

* noel32imafd

* noel64imac

* noel64imafd

* noel64imafdc

The start of the memory is set to 0x0 to match a standard NOEL-V system, but
can be changed using the ``RISCV_RAM_REGION_BEGIN`` configuration option. The
size of the memory is taken from the information available in the device tree.

Reference Designs
-----------------

The BSP has been tested with NOEL-V reference designs for `Digilent Arty A7
<https://gaisler.com/noel-artya7>`_, `Microchip PolarFire Splash Kit
<https://gaisler.com/noel-pf>`_, and `Xilinx KCU105
<https://gaisler.com/noel-xcku>`_.  See the accompanying quickstart guide for
each reference design to determine which BSP configuration to use.

Build Configuration Options
---------------------------

The following options can be used in the BSP section of the ``waf``
configuration INI file. The ``waf`` defaults can be used to inspect the values.

``BSP_CONSOLE_USE_INTERRUPTS``
     Use the Termios interrupt mode in the console driver (true by default).

``BSP_FDT_BLOB_SIZE_MAX``
    The maximum size of the device tree blob in bytes (262144 by default).

``RISCV_CONSOLE_MAX_APBUART_DEVICES``
     The maximum number of APBUART devices supported by the console driver
     (2 by default).

``RISCV_RAM_REGION_BEGIN``
     The begin of the RAM region for linker command file (0x0 by default).

``RISCV_MAXIMUM_EXTERNAL_INTERRUPTS``
     The maximum number of external interrupts supported by the BSP (64 by
     default).

griscv
======

This RISC-V BSP supports chips using the
`GRLIB <https://www.gaisler.com/products/grlib/grlib.pdf>`_.