Re: [PATCH V3 12/20] RISC-V: cpufeature: Add ACPI support in riscv_fill_hwcap()

[Andrew Jones]

On Fri, Mar 03, 2023 at 07:06:39PM +0530, Sunil V L wrote:
> On ACPI based systems, the information about the hart
> like ISA is provided by the RISC-V Hart Capabilities Table (RHCT).
> Enable filling up hwcap structure based on the information in RHCT.
> 
> Signed-off-by: Sunil V L <sunilvl@xxxxxxxxxxxxxxxx>
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
>  arch/riscv/kernel/cpufeature.c | 41 ++++++++++++++++++++++++++--------
>  1 file changed, 32 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 59d58ee0f68d..478dbf129922 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -6,6 +6,7 @@
>   * Copyright (C) 2017 SiFive
>   */
>  
> +#include <linux/acpi.h>
>  #include <linux/bitmap.h>
>  #include <linux/ctype.h>
>  #include <linux/libfdt.h>
> @@ -13,6 +14,8 @@
>  #include <linux/memory.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <asm/acpi.h>
>  #include <asm/alternative.h>
>  #include <asm/cacheflush.h>
>  #include <asm/errata_list.h>
> @@ -91,7 +94,9 @@ void __init riscv_fill_hwcap(void)
>  	char print_str[NUM_ALPHA_EXTS + 1];
>  	int i, j, rc;
>  	unsigned long isa2hwcap[26] = {0};
> -	unsigned long hartid;
> +	struct acpi_table_header *rhct;
> +	acpi_status status;
> +	unsigned int cpu;
>  
>  	isa2hwcap['i' - 'a'] = COMPAT_HWCAP_ISA_I;
>  	isa2hwcap['m' - 'a'] = COMPAT_HWCAP_ISA_M;
> @@ -104,18 +109,33 @@ void __init riscv_fill_hwcap(void)
>  
>  	bitmap_zero(riscv_isa, RISCV_ISA_EXT_MAX);
>  
> -	for_each_of_cpu_node(node) {
> +	if (!acpi_disabled) {
> +		status = acpi_get_table(ACPI_SIG_RHCT, 0, &rhct);
> +		if (ACPI_FAILURE(status))
> +			return;
> +	}
> +
> +	for_each_possible_cpu(cpu) {
>  		unsigned long this_hwcap = 0;
>  		DECLARE_BITMAP(this_isa, RISCV_ISA_EXT_MAX);
>  		const char *temp;
>  
> -		rc = riscv_of_processor_hartid(node, &hartid);
> -		if (rc < 0)
> -			continue;

The above is an unrelated cleanup and should be in a separate patch.

> -
> -		if (of_property_read_string(node, "riscv,isa", &isa)) {
> -			pr_warn("Unable to find \"riscv,isa\" devicetree entry\n");
> -			continue;
> +		if (acpi_disabled) {
> +			node = of_cpu_device_node_get(cpu);
> +			if (node) {
> +				rc = of_property_read_string(node, "riscv,isa", &isa);
> +				of_node_put(node);
> +				if (rc) {
> +					pr_warn("Unable to find \"riscv,isa\" devicetree entry\n");
> +					continue;
> +				}
> +			}
> +		} else {
> +			rc = acpi_get_riscv_isa(rhct, get_acpi_id_for_cpu(cpu), &isa);
> +			if (rc < 0) {
> +				pr_warn("Unable to get ISA for the hart - %d\n", cpu);
> +				continue;
> +			}
>  		}
>  
>  		temp = isa;
> @@ -248,6 +268,9 @@ void __init riscv_fill_hwcap(void)
>  			bitmap_and(riscv_isa, riscv_isa, this_isa, RISCV_ISA_EXT_MAX);
>  	}
>  
> +	if (!acpi_disabled && rhct)
> +		acpi_put_table((struct acpi_table_header *)rhct);
> +
>  	/* We don't support systems with F but without D, so mask those out
>  	 * here. */
>  	if ((elf_hwcap & COMPAT_HWCAP_ISA_F) && !(elf_hwcap & COMPAT_HWCAP_ISA_D)) {
> -- 
> 2.34.1
>

Otherwise,

Reviewed-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx>

Thanks,
drew