[RFC PATCH 3/3] lib: sbi: Implement SBI debug console extension

[Atish Patra]

On Thu, Nov 10, 2022 at 9:01 AM Anup Patel <apatel at ventanamicro.com> wrote:
>
> We implement SBI debug console extension as one of the replacement
> SBI extensions. This extension is only available when OpenSBI platform
> provides a console device to generic library.
>
> Signed-off-by: Anup Patel <apatel at ventanamicro.com>
> ---
>  lib/sbi/Kconfig             |  4 ++++
>  lib/sbi/objects.mk          |  1 +
>  lib/sbi/sbi_ecall_replace.c | 30 ++++++++++++++++++++++++++++++
>  3 files changed, 35 insertions(+)
>
> diff --git a/lib/sbi/Kconfig b/lib/sbi/Kconfig
> index df74bba..ef6728b 100644
> --- a/lib/sbi/Kconfig
> +++ b/lib/sbi/Kconfig
> @@ -26,6 +26,10 @@ config SBI_ECALL_PMU
>         bool "Performance Monitoring Unit extension"
>         default y
>
> +config SBI_ECALL_DBCN
> +       bool "Debug Console extension"
> +       default y
> +
>  config SBI_ECALL_LEGACY
>         bool "SBI v0.1 legacy extensions"
>         default y
> diff --git a/lib/sbi/objects.mk b/lib/sbi/objects.mk
> index 783c46d..7ccad52 100644
> --- a/lib/sbi/objects.mk
> +++ b/lib/sbi/objects.mk
> @@ -23,6 +23,7 @@ carray-sbi_ecall_exts-y += ecall_base
>  carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_HSM) += ecall_hsm
>  carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_SRST) += ecall_srst
>  carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_PMU) += ecall_pmu
> +carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_DBCN) += ecall_dbcn
>  carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_LEGACY) += ecall_legacy
>  carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_VENDOR) += ecall_vendor
>
> diff --git a/lib/sbi/sbi_ecall_replace.c b/lib/sbi/sbi_ecall_replace.c
> index 0ea00d6..a092e2f 100644
> --- a/lib/sbi/sbi_ecall_replace.c
> +++ b/lib/sbi/sbi_ecall_replace.c
> @@ -9,6 +9,7 @@
>   */
>
>  #include <sbi/riscv_asm.h>
> +#include <sbi/sbi_console.h>
>  #include <sbi/sbi_ecall.h>
>  #include <sbi/sbi_ecall_interface.h>
>  #include <sbi/sbi_error.h>
> @@ -202,3 +203,32 @@ struct sbi_ecall_extension ecall_srst = {
>         .probe = sbi_ecall_srst_probe,
>  };
>  #endif
> +
> +#ifdef CONFIG_SBI_ECALL_DBCN
> +static int sbi_ecall_dbcn_handler(unsigned long extid, unsigned long funcid,
> +                                 const struct sbi_trap_regs *regs,
> +                                 unsigned long *out_val,
> +                                 struct sbi_trap_info *out_trap)
> +{
> +       if (funcid == SBI_EXT_DBCN_CONSOLE_PUTS) {
> +               /* TODO: sanity check on the physical address range */

We need PMP validation to ensure that it is not one of the M-mode
reserved addresses.
What else needed to be done here ?

> +               sbi_nputs((const char *)regs->a1, regs->a0);
> +               return 0;
> +       }
> +
> +       return SBI_ENOTSUPP;
> +}
> +
> +static int sbi_ecall_dbcn_probe(unsigned long extid, unsigned long *out_val)
> +{
> +       *out_val = (sbi_console_get_device()) ? 1 : 0;
> +       return 0;
> +}
> +
> +struct sbi_ecall_extension ecall_dbcn = {
> +       .extid_start = SBI_EXT_DBCN,
> +       .extid_end = SBI_EXT_DBCN,
> +       .handle = sbi_ecall_dbcn_handler,
> +       .probe = sbi_ecall_dbcn_probe,
> +};
> +#endif
> --
> 2.34.1
>


--
Regards,
Atish