qemu-patch-raspberry4/docs/system/arm/mps2.rst
Peter Maydell f1dfab0d9b hw/arm/mps2-tz: Implement AN524 memory remapping via machine property
The AN524 FPGA image supports two memory maps, which differ in where
the QSPI and BRAM are.  In the default map, the BRAM is at
0x0000_0000, and the QSPI at 0x2800_0000.  In the second map, they
are the other way around.

In hardware, the initial mapping can be selected by the user by
writing either "REMAP: BRAM" (the default) or "REMAP: QSPI" in the
board configuration file.  The board config file is acted on by the
"Motherboard Configuration Controller", which is an entirely separate
microcontroller on the dev board but outside the FPGA.

The guest can also dynamically change the mapping via the SCC
CFG_REG0 register.

Implement this functionality for QEMU, using a machine property
"remap" with valid values "BRAM" and "QSPI" to allow the user to set
the initial mapping, in the same way they can on the FPGA, and
wiring up the bit from the SCC register to also switch the mapping.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20210504120912.23094-4-peter.maydell@linaro.org
2021-05-10 17:21:54 +01:00

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Arm MPS2 and MPS3 boards (``mps2-an385``, ``mps2-an386``, ``mps2-an500``, ``mps2-an505``, ``mps2-an511``, ``mps2-an521``, ``mps3-an524``, ``mps3-an547``)
=========================================================================================================================================================
These board models all use Arm M-profile CPUs.
The Arm MPS2, MPS2+ and MPS3 dev boards are FPGA based (the 2+ has a
bigger FPGA but is otherwise the same as the 2; the 3 has a bigger
FPGA again, can handle 4GB of RAM and has a USB controller and QSPI flash).
Since the CPU itself and most of the devices are in the FPGA, the
details of the board as seen by the guest depend significantly on the
FPGA image.
QEMU models the following FPGA images:
``mps2-an385``
Cortex-M3 as documented in Arm Application Note AN385
``mps2-an386``
Cortex-M4 as documented in Arm Application Note AN386
``mps2-an500``
Cortex-M7 as documented in Arm Application Note AN500
``mps2-an505``
Cortex-M33 as documented in Arm Application Note AN505
``mps2-an511``
Cortex-M3 'DesignStart' as documented in Arm Application Note AN511
``mps2-an521``
Dual Cortex-M33 as documented in Arm Application Note AN521
``mps3-an524``
Dual Cortex-M33 on an MPS3, as documented in Arm Application Note AN524
``mps3-an547``
Cortex-M55 on an MPS3, as documented in Arm Application Note AN547
Differences between QEMU and real hardware:
- AN385/AN386 remapping of low 16K of memory to either ZBT SSRAM1 or to
block RAM is unimplemented (QEMU always maps this to ZBT SSRAM1, as
if zbt_boot_ctrl is always zero)
- AN524 remapping of low memory to either BRAM or to QSPI flash is
unimplemented (QEMU always maps this to BRAM, ignoring the
SCC CFG_REG0 memory-remap bit)
- QEMU provides a LAN9118 ethernet rather than LAN9220; the only guest
visible difference is that the LAN9118 doesn't support checksum
offloading
- QEMU does not model the QSPI flash in MPS3 boards as real QSPI
flash, but only as simple ROM, so attempting to rewrite the flash
from the guest will fail
- QEMU does not model the USB controller in MPS3 boards
Machine-specific options
""""""""""""""""""""""""
The following machine-specific options are supported:
remap
Supported for ``mps3-an524`` only.
Set ``BRAM``/``QSPI`` to select the initial memory mapping. The
default is ``BRAM``.