Re: [PATCH v2] lib: utils: fdt_helper: simplify fdt_parse_isa_extensions() helper

[Xiang W <wxjstz@126.com>]

在 2025-09-06六的 15:26 +0800，Yu-Chien Peter Lin写道：
> The fdt_isa_bitmap was previously used as a temporary array
> to store ISA extensions when parsing device-tree.
> To reduce scratch space consumption, set the ISA bitmap
> directly in hfeature->extensions, allows us to remove the
> fdt_parse_isa_all_harts() as fdt_parse_isa_extensions() can
> now handle the task directly.
> 
> This change makes the helper function more versatile, even
> before scratch space is initialized.
> 
> Signed-off-by: Yu-Chien Peter Lin <peter.lin@sifive.com>
LGTM

Signed-off-by: Xiang W <wxjstz@126.com>
> ---
>  include/sbi_utils/fdt/fdt_helper.h |  3 +-
>  lib/utils/fdt/fdt_helper.c         | 48 ++++--------------------------
>  platform/generic/platform.c        |  2 +-
>  3 files changed, 7 insertions(+), 46 deletions(-)
> 
> diff --git a/include/sbi_utils/fdt/fdt_helper.h b/include/sbi_utils/fdt/fdt_helper.h
> index 04c850cc..24ad1a94 100644
> --- a/include/sbi_utils/fdt/fdt_helper.h
> +++ b/include/sbi_utils/fdt/fdt_helper.h
> @@ -54,8 +54,7 @@ int fdt_parse_cbom_block_size(const void *fdt, int cpu_offset, unsigned long  *c
>  
>  int fdt_parse_timebase_frequency(const void *fdt, unsigned long *freq);
>  
> -int fdt_parse_isa_extensions(const void *fdt, unsigned int hartid,
> -			     unsigned long *extensions);
> +int fdt_parse_isa_extensions(const void *fdt, unsigned long *hart_exts);
>  
>  int fdt_parse_gaisler_uart_node(const void *fdt, int nodeoffset,
>  				struct platform_uart_data *uart);
> diff --git a/lib/utils/fdt/fdt_helper.c b/lib/utils/fdt/fdt_helper.c
> index 0f4859c1..252dd459 100644
> --- a/lib/utils/fdt/fdt_helper.c
> +++ b/lib/utils/fdt/fdt_helper.c
> @@ -324,8 +324,6 @@ int fdt_parse_timebase_frequency(const void *fdt, unsigned long *freq)
>  
>  #define RISCV_ISA_EXT_NAME_LEN_MAX	32
>  
> -static unsigned long fdt_isa_bitmap_offset;
> -
>  static int fdt_parse_isa_one_hart(const char *isa, unsigned long *extensions)
>  {
>  	size_t i, j, isa_len;
> @@ -405,15 +403,13 @@ static void fdt_parse_isa_extensions_one_hart(const char *isa,
>  	}
>  }
>  
> -static int fdt_parse_isa_all_harts(const void *fdt)
> +int fdt_parse_isa_extensions(const void *fdt, unsigned long *hart_exts)
>  {
>  	u32 hartid;
>  	const fdt32_t *val;
> -	unsigned long *hart_exts;
> -	struct sbi_scratch *scratch;
>  	int err, cpu_offset, cpus_offset, len;
>  
> -	if (!fdt || !fdt_isa_bitmap_offset)
> +	if (!fdt || !hart_exts)
>  		return SBI_EINVAL;
>  
>  	cpus_offset = fdt_path_offset(fdt, "/cpus");
> @@ -425,15 +421,11 @@ static int fdt_parse_isa_all_harts(const void *fdt)
>  		if (err)
>  			continue;
>  
> -		if (!fdt_node_is_enabled(fdt, cpu_offset))
> +		if (hartid != current_hartid())
>  			continue;
>  
> -		scratch = sbi_hartid_to_scratch(hartid);
> -		if (!scratch)
> -			return SBI_ENOENT;
> -
> -		hart_exts = sbi_scratch_offset_ptr(scratch,
> -						   fdt_isa_bitmap_offset);
> +		if (!fdt_node_is_enabled(fdt, cpu_offset))
> +			continue;
>  
>  		val = fdt_getprop(fdt, cpu_offset, "riscv,isa-extensions", &len);
>  		if (val && len > 0) {
> @@ -454,36 +446,6 @@ static int fdt_parse_isa_all_harts(const void *fdt)
>  	return 0;
>  }
>  
> -int fdt_parse_isa_extensions(const void *fdt, unsigned int hartid,
> -			unsigned long *extensions)
> -{
> -	int rc, i;
> -	unsigned long *hart_exts;
> -	struct sbi_scratch *scratch;
> -
> -	if (!fdt_isa_bitmap_offset) {
> -		fdt_isa_bitmap_offset = sbi_scratch_alloc_offset(
> -					sizeof(*hart_exts) *
> -					BITS_TO_LONGS(SBI_HART_EXT_MAX));
> -		if (!fdt_isa_bitmap_offset)
> -			return SBI_ENOMEM;
> -
> -		rc = fdt_parse_isa_all_harts(fdt);
> -		if (rc)
> -			return rc;
> -	}
> -
> -	scratch = sbi_hartid_to_scratch(hartid);
> -	if (!scratch)
> -		return SBI_ENOENT;
> -
> -	hart_exts = sbi_scratch_offset_ptr(scratch, fdt_isa_bitmap_offset);
> -
> -	for (i = 0; i < BITS_TO_LONGS(SBI_HART_EXT_MAX); i++)
> -		extensions[i] |= hart_exts[i];
> -	return 0;
> -}
> -
>  static int fdt_parse_uart_node_common(const void *fdt, int nodeoffset,
>  				      struct platform_uart_data *uart,
>  				      unsigned long default_freq,
> diff --git a/platform/generic/platform.c b/platform/generic/platform.c
> index 47e771ad..2e8c6051 100644
> --- a/platform/generic/platform.c
> +++ b/platform/generic/platform.c
> @@ -251,7 +251,7 @@ int generic_final_init(bool cold_boot)
>  int generic_extensions_init(struct sbi_hart_features *hfeatures)
>  {
>  	/* Parse the ISA string from FDT and enable the listed extensions */
> -	return fdt_parse_isa_extensions(fdt_get_address(), current_hartid(),
> +	return fdt_parse_isa_extensions(fdt_get_address(),
>  					hfeatures->extensions);
>  }
>  
> -- 
> 2.48.0
> 


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