Merge remote-tracking branch 'remotes/alistair/tags/pull-riscv-to-apply-20210511' into staging

A large collection of RISC-V fixes, improvements and features

 - Clenaup some left over v1.9 code
 - Documentation improvements
 - Support for the shakti_c machine
 - Internal cleanup of the CSR accesses
 - Updates to the OpenTitan platform
 - Support for the virtio-vga
 - Fix for the saturate subtract in vector extensions
 - Experimental support for the ePMP spec
 - A range of other internal code cleanups and bug fixes

# gpg: Signature made Tue 11 May 2021 11:17:10 BST
# gpg:                using RSA key F6C4AC46D4934868D3B8CE8F21E10D29DF977054
# gpg: Good signature from "Alistair Francis <alistair@alistair23.me>" [full]
# Primary key fingerprint: F6C4 AC46 D493 4868 D3B8  CE8F 21E1 0D29 DF97 7054

* remotes/alistair/tags/pull-riscv-to-apply-20210511: (42 commits)
  target/riscv: Fix the RV64H decode comment
  target/riscv: Consolidate RV32/64 16-bit instructions
  target/riscv: Consolidate RV32/64 32-bit instructions
  target/riscv: Remove an unused CASE_OP_32_64 macro
  target/riscv: Remove the unused HSTATUS_WPRI macro
  target/riscv: Remove the hardcoded SATP_MODE macro
  target/riscv: Remove the hardcoded MSTATUS_SD macro
  target/riscv: Remove the hardcoded HGATP_MODE macro
  target/riscv: Remove the hardcoded SSTATUS_SD macro
  target/riscv: Remove the hardcoded RVXLEN macro
  target/riscv: fix a typo with interrupt names
  fpu/softfloat: set invalid excp flag for RISC-V muladd instructions
  hw/riscv: Fix OT IBEX reset vector
  target/riscv: fix exception index on instruction access fault
  target/riscv: fix vrgather macro index variable type bug
  target/riscv: Add ePMP support for the Ibex CPU
  target/riscv/pmp: Remove outdated comment
  target/riscv: Add a config option for ePMP
  target/riscv: Implementation of enhanced PMP (ePMP)
  target/riscv: Add ePMP CSR access functions
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

3 files changed, 89 insertions, 3 deletions

diff --git a/docs/system/generic-loader.rst b/docs/system/generic-loader.rst
index 6bf8a4e..531ddbc 100644
--- a/docs/system/generic-loader.rst
+++ b/docs/system/generic-loader.rst
@@ -92,9 +92,12 @@ shown below:
   specified in the executable format header. This option should only
   be used for the boot image. This will also cause the image to be
   written to the specified CPU's address space. If not specified, the
-  default is CPU 0. <force-raw> - Setting force-raw=on forces the file
-  to be treated as a raw image. This can be used to load supported
-  executable formats as if they were raw.
+  default is CPU 0.
+
+``<force-raw>``
+  Setting 'force-raw=on' forces the file to be treated as a raw image.
+  This can be used to load supported executable formats as if they
+  were raw.
 
 All values are parsed using the standard QemuOpts parsing. This allows the user
 to specify any values in any format supported. By default the values
diff --git a/docs/system/riscv/shakti-c.rst b/docs/system/riscv/shakti-c.rst
new file mode 100644
index 0000000..a6035d4
--- /dev/null
+++ b/docs/system/riscv/shakti-c.rst
@@ -0,0 +1,82 @@
+Shakti C Reference Platform (``shakti_c``)
+==========================================
+
+Shakti C Reference Platform is a reference platform based on arty a7 100t
+for the Shakti SoC.
+
+Shakti SoC is a SoC based on the Shakti C-class processor core. Shakti C
+is a 64bit RV64GCSUN processor core.
+
+For more details on Shakti SoC, please see:
+https://gitlab.com/shaktiproject/cores/shakti-soc/-/blob/master/fpga/boards/artya7-100t/c-class/README.rst
+
+For more info on the Shakti C-class core, please see:
+https://c-class.readthedocs.io/en/latest/
+
+Supported devices
+-----------------
+
+The ``shakti_c`` machine supports the following devices:
+
+ * 1 C-class core
+ * Core Level Interruptor (CLINT)
+ * Platform-Level Interrupt Controller (PLIC)
+ * 1 UART
+
+Boot options
+------------
+
+The ``shakti_c`` machine can start using the standard -bios
+functionality for loading the baremetal application or opensbi.
+
+Boot the machine
+----------------
+
+Shakti SDK
+~~~~~~~~~~
+Shakti SDK can be used to generate the baremetal example UART applications.
+
+.. code-block:: bash
+
+   $ git clone https://gitlab.com/behindbytes/shakti-sdk.git
+   $ cd shakti-sdk
+   $ make software PROGRAM=loopback TARGET=artix7_100t
+
+Binary would be generated in:
+  software/examples/uart_applns/loopback/output/loopback.shakti
+
+You could also download the precompiled example applicatons using below
+commands.
+
+.. code-block:: bash
+
+   $ wget -c https://gitlab.com/behindbytes/shakti-binaries/-/raw/master/sdk/shakti_sdk_qemu.zip
+   $ unzip shakti_sdk_qemu.zip
+
+Then we can run the UART example using:
+
+.. code-block:: bash
+
+   $ qemu-system-riscv64 -M shakti_c -nographic \
+      -bios path/to/shakti_sdk_qemu/loopback.shakti
+
+OpenSBI
+~~~~~~~
+We can also run OpenSBI with Test Payload.
+
+.. code-block:: bash
+
+   $ git clone https://github.com/riscv/opensbi.git -b v0.9
+   $ cd opensbi
+   $ wget -c https://gitlab.com/behindbytes/shakti-binaries/-/raw/master/dts/shakti.dtb
+   $ export CROSS_COMPILE=riscv64-unknown-elf-
+   $ export FW_FDT_PATH=./shakti.dtb
+   $ make PLATFORM=generic
+
+fw_payload.elf would be generated in build/platform/generic/firmware/fw_payload.elf.
+Boot it using the below qemu command.
+
+.. code-block:: bash
+
+   $ qemu-system-riscv64 -M shakti_c -nographic \
+      -bios path/to/fw_payload.elf
diff --git a/docs/system/target-riscv.rst b/docs/system/target-riscv.rst
index 8d5946f..4b3c783 100644
--- a/docs/system/target-riscv.rst
+++ b/docs/system/target-riscv.rst
@@ -67,6 +67,7 @@ undocumented; you can get a complete list by running
    :maxdepth: 1
 
    riscv/microchip-icicle-kit
+   riscv/shakti-c
    riscv/sifive_u
 
 RISC-V CPU features