Re: [PATCH 19/24] RISC-V: ACPI: cpufeature: Add ACPI support in riscv_fill_hwcap()

[Conor Dooley <conor@kernel.org>]

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On Mon, Jan 30, 2023 at 11:52:20PM +0530, Sunil V L wrote:
> On ACPI based systems, the information about the hart
> like ISA, extesions supported are defined in RISC-V Hart
> Capabilities Table (RHCT). Enable filling up hwcap structure
> based on the information in RHCT.
> 
> Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
> ---
>  arch/riscv/kernel/cpufeature.c | 45 ++++++++++++++++++++++++++++------
>  1 file changed, 38 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 93e45560af30..c10177c608f8 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -6,12 +6,14 @@
>   * Copyright (C) 2017 SiFive
>   */
>  
> +#include <linux/acpi.h>
>  #include <linux/bitmap.h>
>  #include <linux/ctype.h>
>  #include <linux/libfdt.h>
>  #include <linux/log2.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> +#include <asm/acpi.h>
>  #include <asm/alternative.h>
>  #include <asm/cacheflush.h>
>  #include <asm/errata_list.h>
> @@ -21,6 +23,7 @@
>  #include <asm/processor.h>
>  #include <asm/smp.h>
>  #include <asm/switch_to.h>
> +#include <linux/of_device.h>

Is there a reason this header is not added with the other linux ones?

>  
>  #define NUM_ALPHA_EXTS ('z' - 'a' + 1)
>  
> @@ -93,7 +96,10 @@ void __init riscv_fill_hwcap(void)
>  	char print_str[NUM_ALPHA_EXTS + 1];
>  	int i, j, rc;
>  	unsigned long isa2hwcap[26] = {0};
> +	struct acpi_table_header *rhct;
> +	acpi_status status;
>  	unsigned long hartid;
> +	unsigned int cpu;
>  
>  	isa2hwcap['i' - 'a'] = COMPAT_HWCAP_ISA_I;
>  	isa2hwcap['m' - 'a'] = COMPAT_HWCAP_ISA_M;
> @@ -106,18 +112,38 @@ void __init riscv_fill_hwcap(void)
>  
>  	bitmap_zero(riscv_isa, RISCV_ISA_EXT_MAX);
>  
> -	for_each_of_cpu_node(node) {
> +	if (!acpi_disabled) {
> +

Extraneous blank line.

> +		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;
> +		if (acpi_disabled) {
> +			node = of_cpu_device_node_get(cpu);
> +			if (node) {
> +				rc = riscv_of_processor_hartid(node, &hartid);
> +				if (rc < 0)
> +					continue;
>  
> -		if (of_property_read_string(node, "riscv,isa", &isa)) {
> -			pr_warn("Unable to find \"riscv,isa\" devicetree entry\n");
> -			continue;
> +				if (of_property_read_string(node, "riscv,isa", &isa)) {
> +					pr_warn("Unable to find \"riscv,isa\" devicetree entry\n");
> +					continue;
> +				}
> +				of_node_put(node);
> +			}
> +		} 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);

The alignment here is wrong, but the whole thing fits on a single line.

> +				continue;
> +			}
>  		}
>  
>  		temp = isa;
> @@ -248,6 +274,11 @@ void __init riscv_fill_hwcap(void)
>  			bitmap_and(riscv_isa, riscv_isa, this_isa, RISCV_ISA_EXT_MAX);
>  	}
>  
> +#ifdef CONFIG_ACPI

Is this guard actually needed, or is acpi_put_table() always available?

Cheers,
Conor.

> +	if (!acpi_disabled)
> +		acpi_put_table((struct acpi_table_header *)rhct);
> +#endif
> +
>  	/* 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)) {
> -- 
> 2.38.0
> 

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