[PATCH 1/2] lib: sbi: hart: Detect existence of cycle and instret CSRs for Zicntr

[Xiang W]

在 2025-02-25二的 15:41 +0000，Yao Zi写道：
> Zicntr extension specifies three RO CSRs, time, cycle and instret. It
remove 'R0'

Regards,
Xiang W
> isn't precise to report Zicntr is fully supported with only time CSR
> detected.
> 
> Since CSR emulating code only cares about the availablity of time CSR,
> add additional definitions to represent the existance of cycle and
> instret CSRs.
> 
> Signed-off-by: Yao Zi <ziyao at disroot.org>
> ---
>  include/sbi/sbi_hart.h |  8 ++++++--
>  lib/sbi/sbi_hart.c     | 30 ++++++++++++++++++++++--------
>  lib/sbi/sbi_timer.c    |  2 +-
>  3 files changed, 29 insertions(+), 11 deletions(-)
> 
> diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
> index 4c36c77..0a740cf 100644
> --- a/include/sbi/sbi_hart.h
> +++ b/include/sbi/sbi_hart.h
> @@ -37,8 +37,12 @@ enum sbi_hart_extensions {
>  	SBI_HART_EXT_SSCOFPMF,
>  	/** HART has Sstc extension */
>  	SBI_HART_EXT_SSTC,
> -	/** HART has Zicntr extension (i.e. HW cycle, time & instret CSRs) */
> -	SBI_HART_EXT_ZICNTR,
> +	/** HART has HW time CSR, as specified in Zicntr extension */
> +	SBI_HART_EXT_ZICNTR_TIME,
> +	/** HART has HW cycle CSR, as specified in Zicntr extension */
> +	SBI_HART_EXT_ZICNTR_CYCLE,
> +	/** HART has HW instret CSR, as specified in Zicntr extension */
> +	SBI_HART_EXT_ZICNTR_INSTRET,
>  	/** HART has Zihpm extension */
>  	SBI_HART_EXT_ZIHPM,
>  	/** HART has Zkr extension */
> diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
> index 8e2979b..e1d630d 100644
> --- a/lib/sbi/sbi_hart.c
> +++ b/lib/sbi/sbi_hart.c
> @@ -669,7 +669,9 @@ const struct sbi_hart_ext_data sbi_hart_ext[] = {
>  	__SBI_HART_EXT_DATA(smstateen, SBI_HART_EXT_SMSTATEEN),
>  	__SBI_HART_EXT_DATA(sscofpmf, SBI_HART_EXT_SSCOFPMF),
>  	__SBI_HART_EXT_DATA(sstc, SBI_HART_EXT_SSTC),
> -	__SBI_HART_EXT_DATA(zicntr, SBI_HART_EXT_ZICNTR),
> +	__SBI_HART_EXT_DATA(zicntr_time, SBI_HART_EXT_ZICNTR_TIME),
> +	__SBI_HART_EXT_DATA(zicntr_cycle, SBI_HART_EXT_ZICNTR_CYCLE),
> +	__SBI_HART_EXT_DATA(zicntr_instret, SBI_HART_EXT_ZICNTR_INSTRET),
>  	__SBI_HART_EXT_DATA(zihpm, SBI_HART_EXT_ZIHPM),
>  	__SBI_HART_EXT_DATA(zkr, SBI_HART_EXT_ZKR),
>  	__SBI_HART_EXT_DATA(smcntrpmf, SBI_HART_EXT_SMCNTRPMF),
> @@ -782,7 +784,7 @@ static int hart_detect_features(struct sbi_scratch *scratch)
>  	struct sbi_hart_features *hfeatures =
>  		sbi_scratch_offset_ptr(scratch, hart_features_offset);
>  	unsigned long val, oldval;
> -	bool has_zicntr = false;
> +	bool has_time = false, has_cycle = false, has_instret = false;
>  	int rc;
>  
>  	/* If hart features already detected then do nothing */
> @@ -919,7 +921,13 @@ __pmp_skip:
>  			CSR_SCOUNTOVF, SBI_HART_EXT_SSCOFPMF);
>  	/* Detect if hart supports time CSR */
>  	__check_ext_csr(SBI_HART_PRIV_VER_UNKNOWN,
> -			CSR_TIME, SBI_HART_EXT_ZICNTR);
> +			CSR_TIME, SBI_HART_EXT_ZICNTR_TIME);
> +	/* Detect if hart supports cycle CSR */
> +	__check_ext_csr(SBI_HART_PRIV_VER_UNKNOWN,
> +			CSR_CYCLE, SBI_HART_EXT_ZICNTR_CYCLE);
> +	/* Detect if hart supports instret CSR */
> +	__check_ext_csr(SBI_HART_PRIV_VER_UNKNOWN,
> +			CSR_INSTRET, SBI_HART_EXT_ZICNTR_INSTRET);
>  	/* Detect if hart has AIA local interrupt CSRs */
>  	__check_ext_csr(SBI_HART_PRIV_VER_UNKNOWN,
>  			CSR_MTOPI, SBI_HART_EXT_SMAIA);
> @@ -938,8 +946,10 @@ __pmp_skip:
>  
>  #undef __check_ext_csr
>  
> -	/* Save trap based detection of Zicntr */
> -	has_zicntr = sbi_hart_has_extension(scratch, SBI_HART_EXT_ZICNTR);
> +	/* Save trap based detection of Zicntr CSRs */
> +	has_time = sbi_hart_has_extension(scratch, SBI_HART_EXT_ZICNTR_TIME);
> +	has_cycle = sbi_hart_has_extension(scratch, SBI_HART_EXT_ZICNTR_CYCLE);
> +	has_instret = sbi_hart_has_extension(scratch, SBI_HART_EXT_ZICNTR_INSTRET);
>  
>  	/* Let platform populate extensions */
>  	rc = sbi_platform_extensions_init(sbi_platform_thishart_ptr(),
> @@ -947,9 +957,13 @@ __pmp_skip:
>  	if (rc)
>  		return rc;
>  
> -	/* Zicntr should only be detected using traps */
> -	__sbi_hart_update_extension(hfeatures, SBI_HART_EXT_ZICNTR,
> -				    has_zicntr);
> +	/* Zicntr CSRs should only be detected using traps */
> +	__sbi_hart_update_extension(hfeatures, SBI_HART_EXT_ZICNTR_TIME,
> +				    has_time);
> +	__sbi_hart_update_extension(hfeatures, SBI_HART_EXT_ZICNTR_CYCLE,
> +				    has_cycle);
> +	__sbi_hart_update_extension(hfeatures, SBI_HART_EXT_ZICNTR_INSTRET,
> +				    has_instret);
>  
>  	/* Extensions implied by other extensions and features */
>  	if (hfeatures->mhpm_mask)
> diff --git a/lib/sbi/sbi_timer.c b/lib/sbi/sbi_timer.c
> index 86e0db5..b4db4ca 100644
> --- a/lib/sbi/sbi_timer.c
> +++ b/lib/sbi/sbi_timer.c
> @@ -190,7 +190,7 @@ int sbi_timer_init(struct sbi_scratch *scratch, bool cold_boot)
>  		if (!time_delta_off)
>  			return SBI_ENOMEM;
>  
> -		if (sbi_hart_has_extension(scratch, SBI_HART_EXT_ZICNTR))
> +		if (sbi_hart_has_extension(scratch, SBI_HART_EXT_ZICNTR_TIME))
>  			get_time_val = get_ticks;
>  
>  		ret = sbi_platform_timer_init(plat);
> -- 
> 2.48.1
> 
>