linux-kernel - Re: [External] Re: [PATCH v2] RISC-V: Provide the frequency of time CSR via hwprobe

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Date: Sat, 22 Jun 2024 10:42:25 +0800
From: yunhui cui <cuiyunhui@...edance.com>
To: Jessica Clarke <jrtc27@...c27.com>
Cc: Palmer Dabbelt <palmer@...belt.com>, Jonathan Corbet <corbet@....net>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Clément Léger <cleger@...osinc.com>, 
	Evan Green <evan@...osinc.com>, Conor Dooley <conor.dooley@...rochip.com>, costa.shul@...hat.com, 
	Andy Chiu <andy.chiu@...ive.com>, samitolvanen@...gle.com, linux-doc@...r.kernel.org, 
	linux-riscv <linux-riscv@...ts.infradead.org>, LKML <linux-kernel@...r.kernel.org>, 
	Palmer Dabbelt <palmer@...osinc.com>
Subject: Re: [External] Re: [PATCH v2] RISC-V: Provide the frequency of time
 CSR via hwprobe

Hi Jessica,

On Sat, Jun 22, 2024 at 2:04 AM Jessica Clarke <jrtc27@...c27.com> wrote:
>
> On 21 Jun 2024, at 12:31, Yunhui Cui <cuiyunhui@...edance.com> wrote:
> >
> > From: Palmer Dabbelt <palmer@...osinc.com>
> >
> > A handful of user-visible behavior is based on the frequency of the
> > time CSR.
> >
> > Signed-off-by: Palmer Dabbelt <palmer@...osinc.com>
> > Signed-off-by: Yunhui Cui <cuiyunhui@...edance.com>
> > ---
> > Documentation/arch/riscv/hwprobe.rst  | 2 ++
> > arch/riscv/include/asm/hwprobe.h      | 2 +-
> > arch/riscv/include/uapi/asm/hwprobe.h | 1 +
> > arch/riscv/kernel/sys_hwprobe.c       | 5 +++++
> > 4 files changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/arch/riscv/hwprobe.rst b/Documentation/arch/riscv/hwprobe.rst
> > index fc015b452ebf..c07f159d8906 100644
> > --- a/Documentation/arch/riscv/hwprobe.rst
> > +++ b/Documentation/arch/riscv/hwprobe.rst
> > @@ -229,3 +229,5 @@ The following keys are defined:
> >
> > * :c:macro:`RISCV_HWPROBE_KEY_ZICBOZ_BLOCK_SIZE`: An unsigned int which
> >   represents the size of the Zicboz block in bytes.
> > +
> > +* :c:macro:`RISCV_HWPROBE_KEY_TIME_CSR_FREQ`: Frequency (in Hz) of `mtime`.
>
> This still says mtime.
Okay, I will update it on v3, thanks.

>
> Jess
>
> > diff --git a/arch/riscv/include/asm/hwprobe.h b/arch/riscv/include/asm/hwprobe.h
> > index 630507dff5ea..150a9877b0af 100644
> > --- a/arch/riscv/include/asm/hwprobe.h
> > +++ b/arch/riscv/include/asm/hwprobe.h
> > @@ -8,7 +8,7 @@
> >
> > #include <uapi/asm/hwprobe.h>
> >
> > -#define RISCV_HWPROBE_MAX_KEY 6
> > +#define RISCV_HWPROBE_MAX_KEY 7
> >
> > static inline bool riscv_hwprobe_key_is_valid(__s64 key)
> > {
> > diff --git a/arch/riscv/include/uapi/asm/hwprobe.h b/arch/riscv/include/uapi/asm/hwprobe.h
> > index 7b95fadbea2a..18754341ff14 100644
> > --- a/arch/riscv/include/uapi/asm/hwprobe.h
> > +++ b/arch/riscv/include/uapi/asm/hwprobe.h
> > @@ -73,6 +73,7 @@ struct riscv_hwprobe {
> > #define RISCV_HWPROBE_MISALIGNED_UNSUPPORTED (4 << 0)
> > #define RISCV_HWPROBE_MISALIGNED_MASK (7 << 0)
> > #define RISCV_HWPROBE_KEY_ZICBOZ_BLOCK_SIZE 6
> > +#define RISCV_HWPROBE_KEY_TIME_CSR_FREQ 7
> > /* Increase RISCV_HWPROBE_MAX_KEY when adding items. */
> >
> > /* Flags */
> > diff --git a/arch/riscv/kernel/sys_hwprobe.c b/arch/riscv/kernel/sys_hwprobe.c
> > index 83fcc939df67..fc3b40fb9def 100644
> > --- a/arch/riscv/kernel/sys_hwprobe.c
> > +++ b/arch/riscv/kernel/sys_hwprobe.c
> > @@ -8,6 +8,7 @@
> > #include <asm/cacheflush.h>
> > #include <asm/cpufeature.h>
> > #include <asm/hwprobe.h>
> > +#include <asm/delay.h>
> > #include <asm/sbi.h>
> > #include <asm/switch_to.h>
> > #include <asm/uaccess.h>
> > @@ -226,6 +227,10 @@ static void hwprobe_one_pair(struct riscv_hwprobe *pair,
> > pair->value = riscv_cboz_block_size;
> > break;
> >
> > + case RISCV_HWPROBE_KEY_TIME_CSR_FREQ:
> > + pair->value = riscv_timebase;
> > + break;
> > +
> > /*
> > * For forward compatibility, unknown keys don't fail the whole
> > * call, but get their element key set to -1 and value set to 0
> > --
> > 2.20.1
> >
> >
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@...ts.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
>

Thanks,
Yunhui

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