[PATCH 2/4] riscv: add functions for reading the IPI status

[Rick Chen]

Hi Lukas

> From: Lukas Auer [mailto:lukas.auer at aisec.fraunhofer.de]
> Sent: Wednesday, December 04, 2019 5:40 AM
> To: u-boot at lists.denx.de
> Cc: Rick Jian-Zhi Chen(陳建志); Anup Patel; Bin Meng; Lukas Auer; Anup Patel; Atish Patra
> Subject: [PATCH 2/4] riscv: add functions for reading the IPI status
>
> Add the function riscv_get_ipi() for reading the pending status of IPIs.
> The supported controllers are Andes' Platform Level Interrupt Controller (PLIC), the Supervisor Binary Interface (SBI), and SiFive's Core Local Interruptor (CLINT).
>
> Signed-off-by: Lukas Auer <lukas.auer at aisec.fraunhofer.de>
> ---
> I do not have access to the datasheet of the Andes PLIC. The
> riscv_clear_ipi() implementation seems to read the IPI status from the claim register before writing back the results to clear them. Based on this, I also used the claim register. Rick, please let me know if that is ok or if I should use the pending register instead.

Yes.

Please use pending register instead of claim register.

Thanks
Rick


>
>  arch/riscv/lib/andes_plic.c   |  9 +++++++++
>  arch/riscv/lib/sbi_ipi.c      | 11 +++++++++++
>  arch/riscv/lib/sifive_clint.c |  9 +++++++++
>  arch/riscv/lib/smp.c          | 12 ++++++++++++
>  4 files changed, 41 insertions(+)
>
> diff --git a/arch/riscv/lib/andes_plic.c b/arch/riscv/lib/andes_plic.c index 28568e4e2b..731ac3a148 100644
> --- a/arch/riscv/lib/andes_plic.c
> +++ b/arch/riscv/lib/andes_plic.c
> @@ -114,6 +114,15 @@ int riscv_clear_ipi(int hart)
>         return 0;
>  }
>
> +int riscv_get_ipi(int hart, int *pending) {
> +       PLIC_BASE_GET();
> +
> +       *pending = !!readl((void __iomem *)CLAIM_REG(gd->arch.plic, hart));
> +
> +       return 0;
> +}
> +
>  static const struct udevice_id andes_plic_ids[] = {
>         { .compatible = "riscv,plic1", .data = RISCV_SYSCON_PLIC },
>         { }
> diff --git a/arch/riscv/lib/sbi_ipi.c b/arch/riscv/lib/sbi_ipi.c index 170346da68..9a698ce74e 100644
> --- a/arch/riscv/lib/sbi_ipi.c
> +++ b/arch/riscv/lib/sbi_ipi.c
> @@ -23,3 +23,14 @@ int riscv_clear_ipi(int hart)
>
>         return 0;
>  }
> +
> +int riscv_get_ipi(int hart, int *pending) {
> +       /*
> +        * The SBI does not support reading the IPI status. We always return 0
> +        * to indicate that no IPI is pending.
> +        */
> +       *pending = 0;
> +
> +       return 0;
> +}
> diff --git a/arch/riscv/lib/sifive_clint.c b/arch/riscv/lib/sifive_clint.c index d24e0d585b..d7899d16d7 100644
> --- a/arch/riscv/lib/sifive_clint.c
> +++ b/arch/riscv/lib/sifive_clint.c
> @@ -71,6 +71,15 @@ int riscv_clear_ipi(int hart)
>         return 0;
>  }
>
> +int riscv_get_ipi(int hart, int *pending) {
> +       CLINT_BASE_GET();
> +
> +       *pending = readl((void __iomem *)MSIP_REG(gd->arch.clint, hart));
> +
> +       return 0;
> +}
> +
>  static const struct udevice_id sifive_clint_ids[] = {
>         { .compatible = "riscv,clint0", .data = RISCV_SYSCON_CLINT },
>         { }
> diff --git a/arch/riscv/lib/smp.c b/arch/riscv/lib/smp.c index cc66f15567..6ff0de4b74 100644
> --- a/arch/riscv/lib/smp.c
> +++ b/arch/riscv/lib/smp.c
> @@ -31,6 +31,18 @@ extern int riscv_send_ipi(int hart);
>   */
>  extern int riscv_clear_ipi(int hart);
>
> +/**
> + * riscv_get_ipi() - Get status of inter-processor interrupt (IPI)
> + *
> + * Platform code must provide this function.
> + *
> + * @hart: Hart ID of hart to be checked
> + * @pending: Pointer to variable with result of the check,
> + *           1 if IPI is pending, 0 otherwise
> + * @return 0 if OK, -ve on error
> + */
> +extern int riscv_get_ipi(int hart, int *pending);
> +
>  static int send_ipi_many(struct ipi_data *ipi)  {
>         ofnode node, cpus;
> --
> 2.21.0
>