linux-kernel - Re: [PATCH v4 2/5] RISC-V: Add SBI debug console helper routines

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Message-ID: <CAK9=C2WmFFsVmZZj9j9VwdQOgBiXZOUujoj5VWcycPetkqHRMQ@mail.gmail.com>
Date:   Thu, 23 Nov 2023 16:14:21 +0530
From:   Anup Patel <apatel@...tanamicro.com>
To:     Samuel Holland <samuel.holland@...ive.com>
Cc:     Conor Dooley <conor@...nel.org>,
        Andrew Jones <ajones@...tanamicro.com>,
        linux-riscv@...ts.infradead.org, linux-serial@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>
Subject: Re: [PATCH v4 2/5] RISC-V: Add SBI debug console helper routines

On Wed, Nov 22, 2023 at 4:15 AM Samuel Holland
<samuel.holland@...ive.com> wrote:
>
> Hi Anup,
>
> On 2023-11-17 9:38 PM, Anup Patel wrote:
> > Let us provide SBI debug console helper routines which can be
> > shared by serial/earlycon-riscv-sbi.c and hvc/hvc_riscv_sbi.c.
> >
> > Signed-off-by: Anup Patel <apatel@...tanamicro.com>
> > ---
> >  arch/riscv/include/asm/sbi.h |  5 +++++
> >  arch/riscv/kernel/sbi.c      | 43 ++++++++++++++++++++++++++++++++++++
> >  2 files changed, 48 insertions(+)
> >
> > diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
> > index 66f3933c14f6..ee7aef5f6233 100644
> > --- a/arch/riscv/include/asm/sbi.h
> > +++ b/arch/riscv/include/asm/sbi.h
> > @@ -334,6 +334,11 @@ static inline unsigned long sbi_mk_version(unsigned long major,
> >  }
> >
> >  int sbi_err_map_linux_errno(int err);
> > +
> > +extern bool sbi_debug_console_available;
> > +int sbi_debug_console_write(unsigned int num_bytes, phys_addr_t base_addr);
> > +int sbi_debug_console_read(unsigned int num_bytes, phys_addr_t base_addr);
> > +
> >  #else /* CONFIG_RISCV_SBI */
> >  static inline int sbi_remote_fence_i(const struct cpumask *cpu_mask) { return -1; }
> >  static inline void sbi_init(void) {}
> > diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
> > index 5a62ed1da453..73a9c22c3945 100644
> > --- a/arch/riscv/kernel/sbi.c
> > +++ b/arch/riscv/kernel/sbi.c
> > @@ -571,6 +571,44 @@ long sbi_get_mimpid(void)
> >  }
> >  EXPORT_SYMBOL_GPL(sbi_get_mimpid);
> >
> > +bool sbi_debug_console_available;
> > +
> > +int sbi_debug_console_write(unsigned int num_bytes, phys_addr_t base_addr)
> > +{
> > +     struct sbiret ret;
> > +
> > +     if (!sbi_debug_console_available)
> > +             return -EOPNOTSUPP;
> > +
> > +     if (IS_ENABLED(CONFIG_32BIT))
> > +             ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
> > +                             num_bytes, lower_32_bits(base_addr),
> > +                             upper_32_bits(base_addr), 0, 0, 0);
> > +     else
> > +             ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
> > +                             num_bytes, base_addr, 0, 0, 0, 0);
> > +
> > +     return ret.error ? sbi_err_map_linux_errno(ret.error) : ret.value;
> > +}
> > +
> > +int sbi_debug_console_read(unsigned int num_bytes, phys_addr_t base_addr)
> > +{
> > +     struct sbiret ret;
> > +
> > +     if (!sbi_debug_console_available)
> > +             return -EOPNOTSUPP;
> > +
> > +     if (IS_ENABLED(CONFIG_32BIT))
> > +             ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_READ,
> > +                             num_bytes, lower_32_bits(base_addr),
> > +                             upper_32_bits(base_addr), 0, 0, 0);
> > +     else
> > +             ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_READ,
> > +                             num_bytes, base_addr, 0, 0, 0, 0);
> > +
> > +     return ret.error ? sbi_err_map_linux_errno(ret.error) : ret.value;
> > +}
>
> Since every place that calls these functions will need to do the vmalloc lookup,
> would it make sense to do it here, and have these take a pointer instead?

Yes, that's better. I will update.

Regards,
Anup