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

[Anup Patel]

On Sat, Nov 12, 2022 at 2:24 PM Atish Patra <atishp at atishpatra.org> wrote:
>
> 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 ?

Yes, I need to add required checks here.

Regards,
Anup

>
> > +               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