[U-Boot] [PATCH v2 1/9] riscv: add infrastructure for calling functions on other harts

[Bin Meng]

On Wed, Mar 6, 2019 at 6:54 AM Lukas Auer
<lukas.auer at aisec.fraunhofer.de> wrote:
>
> Harts on RISC-V boot independently, U-Boot is responsible for managing
> them. Functions are called on other harts with smp_call_function(),
> which sends inter-processor interrupts (IPIs) to all other available
> harts. Available harts are those marked as available in the device tree
> and present in the available_harts mask stored in global data. The
> available_harts mask is used to register all harts that have entered
> U-Boot. Functions are specified with their address and two function
> arguments (argument 2 and 3). The first function argument is always the
> hart ID of the hart calling the function. On the other harts, the IPI
> interrupt handler handle_ipi() must be called on software interrupts to
> handle the request and call the specified function.
>
> Functions are stored in the ipi_data data structure. Every hart has its
> own data structure in global data. While this is not required at the
> moment (all harts are expected to boot Linux), this does allow future
> expansion, where other harts may be used for monitoring or other tasks.
>
> Signed-off-by: Lukas Auer <lukas.auer at aisec.fraunhofer.de>
> ---
>
> Changes in v2:
> - Remove unneeded quotes from NR_CPUS Kconfig entry
> - Move memory barrier from send_ipi_many() to handle_ipi()
> - Add check in send_ipi_many so that IPIs are only sent to available
> harts as indicated by the available_harts mask
>
>  arch/riscv/Kconfig                   |  19 +++++
>  arch/riscv/include/asm/global_data.h |   6 ++
>  arch/riscv/include/asm/smp.h         |  53 ++++++++++++
>  arch/riscv/lib/Makefile              |   1 +
>  arch/riscv/lib/smp.c                 | 116 +++++++++++++++++++++++++++
>  5 files changed, 195 insertions(+)
>  create mode 100644 arch/riscv/include/asm/smp.h
>  create mode 100644 arch/riscv/lib/smp.c
>

Reviewed-by: Bin Meng <bmeng.cn at gmail.com>
Tested-by: Bin Meng <bmeng.cn at gmail.com>