linux-kernel - Re: [PATCH v3] RISC-V: Provide the frequency of time CSR via hwprobe

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Date: Wed, 26 Jun 2024 14:01:03 +0100
From: Conor Dooley <conor@...nel.org>
To: Yunhui Cui <cuiyunhui@...edance.com>
Cc: jesse@...osinc.com, jrtc27@...c27.com, corbet@....net,
	paul.walmsley@...ive.com, palmer@...belt.com, aou@...s.berkeley.edu,
	cleger@...osinc.com, evan@...osinc.com, conor.dooley@...rochip.com,
	costa.shul@...hat.com, andy.chiu@...ive.com,
	samitolvanen@...gle.com, linux-doc@...r.kernel.org,
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Palmer Dabbelt <palmer@...osinc.com>,
	Anup Patel <anup@...infault.org>
Subject: Re: [PATCH v3] RISC-V: Provide the frequency of time CSR via hwprobe

On Sat, Jun 22, 2024 at 10:55:14AM +0800, Yunhui Cui 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>
> Reviewed-by: Evan Green <evan@...osinc.com>
> Reviewed-by: Anup Patel <anup@...infault.org>
> ---

What changed between this version and the previous one? You need to
include changelogs under the --- for this purpose.

Thanks,
Conor.

>  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 df5045103e73..ec3c99474ed7 100644
> --- a/Documentation/arch/riscv/hwprobe.rst
> +++ b/Documentation/arch/riscv/hwprobe.rst
> @@ -233,3 +233,5 @@ 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 `time CSR`.
> diff --git a/arch/riscv/include/asm/hwprobe.h b/arch/riscv/include/asm/hwprobe.h
> index 150a9877b0af..ef01c182af2b 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 7
> +#define RISCV_HWPROBE_MAX_KEY 8
>  
>  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 2fb8a8185e7a..5053a9b18710 100644
> --- a/arch/riscv/include/uapi/asm/hwprobe.h
> +++ b/arch/riscv/include/uapi/asm/hwprobe.h
> @@ -74,6 +74,7 @@ struct riscv_hwprobe {
>  #define		RISCV_HWPROBE_MISALIGNED_MASK		(7 << 0)
>  #define RISCV_HWPROBE_KEY_ZICBOZ_BLOCK_SIZE	6
>  #define RISCV_HWPROBE_KEY_MISALIGNED_PERF	7
> +#define RISCV_HWPROBE_KEY_TIME_CSR_FREQ	8
>  /* 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 e4ec9166339f..3d47edc04a3f 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>
> @@ -227,6 +228,10 @@ 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
> 
> 

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