This implements initial support for kernel build (address environments,
page allocator) for RISC-V.
This is done a bit differently compared to the ARMV7 implementation:
- Support implemented for Sv39 MMU, however the implementation should be
extensible for other MMU types also.
- Instead of preserving and moving the L1 references around, a canonical
approach is used instead, where the page table base address register
is switched upon context switch.
- To preserve a bit of memory, only a single L1/L2 table is supported,
this gives access to 1GiB of virtual memory for each process, which
should be more than enough.
Some things worth noting:
- Assumes page pool is mapped with vaddr=paddr mappings
- The CONFIG_ARCH_XXXX_VBASE and CONFIG_ARCH_XXXX_NPAGES values are
ignored, with the exception of CONFIG_ARCH_DATA_VBASE which is used
for ARCH_DATA_RESERVE
- ARCH_DATA_RESERVE is placed at the beginning of the userspace task's
address environment
Summary:
- I noticed that maix-bit:smp does not work with QEMU.
- Actually, QEMU supports sifive_u (not K210) but it works
if FPU is disabled.
- This commit fixes this issue.
Impact:
- K210 with QEMU only
Testing:
- Tested with qemu-5.2
Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>
IRQ_NSTACKS, ARCH_CPU_COUNT, CONFIG_SMP_NCPUS all relate to each
other. However, a bit of clean up can be done and everything can
be merged into SMP_NCPUS.
The MPFS bootloader case works also as it requires only 1 IRQ stack
for the hart that executes as bootloader.
It might be useful to store things in memory per CPU. The tricky part
is that all CPUs run the same code and see the same memory, so some
kind of centralized access is required.
For now, the structure contains the hart id.
Access to the structure elements is provided via sscratch, which is
unique for every hart!
- Add config "ARCH_USE_S_MODE" which controls whether the kernel
runs in M-mode or S-mode
- Add more MSTATUS and most of the SSTATUS register definitions
- Add more MIP flags for interrupt delegation
- Add handling of interrupts from S-mode
- Add handling of FPU from S-mode
- Add new context handling functions that are not dependent on the trap
handlers / ecall
NOTE: S-mode requires a companion SW (SBI) which is not yet implemented,
thus S-mode is not usable as is, yet.
- Add test for mode support, which is architecture dependent
- Add tests for address alignment and region size
- Add option to query for access rights
- The function goes through every PMP entry and tests if an address
range from [base, base+size] has been configured for desired
access rights.
- If several PMP entries match the range and access rights, the
information is combined
- End result is either no access, a partial match was found, or a full
match was found. Details about the partial match are not provided.
The intent for testing access rights and not just blindly applying them
is a case where they are already set in e.g. a bootloader. In this
case, nothing should be done, unless the configuration does not match,
in which case the software must not continue further.
Sv39 is the only mode supported for now. However, it should be trivial
to extend the driver to support the other modes (including Sv32) as well.
The driver is tested with mpfs only, but it should work with any riscv
implementation.
OpenSBI may be compiled as an external library. OpenSBI commit d249d65
(Dec. 11, 2021) needs to be reverted as it causes memcpy / memcmp to
end up in the wrong section. That issue has yet no known workaround.
OpenSBI may be lauched from the hart0 (e51). It will start the U-Boot
and eventually the Linux kernel on harts 1-4.
OpenSBI, once initialized properly, will trap and handle illegal
instructions (for example, CSR time) and unaligned address accesses
among other things.
Due to size size limitations for the mpfs eNVM area where the NuttX
is located, we actually set up the OpenSBI on its own section which
is in the bottom of the DDR memory. Special care must be taken so that
the kernel doesn't override the OpenSBI. For example, the Linux device
tree may reserve some space from the beginning:
opensbi_reserved: opensbi@80000000 {
reg = <0x80000000 0x200000>;
label = "opensbi-reserved";
};
The resulting nuttx.bin file is very large, but objcopy is used to
create the final binary images for the regions (eNVM and DDR) using
the nuttx elf file.
Co-authored-by: Petro Karashchenko <petro.karashchenko@gmail.com>
Signed-off-by: Eero Nurkkala <eero.nurkkala@offcode.fi>
script.
These functions are strongly declared and thus will be used instead of
any other implementation. Furthermore, necessary Kconfig options are
selected to avoid building those function from NuttX's C library.
Signed-off-by: Abdelatif Guettouche <abdelatif.guettouche@espressif.com>
Add a driver for CorePWM block, which can be instantiated on PolarFire SOC FPGA
This supports 2 CorePWM blocks on the FPGA. One CorePWM block provides 8 PWM output signals
