linux-kernel - [PATCH V2 12/21] RISC-V: cpufeature: Add ACPI support in riscv_fill

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Date:   Thu, 16 Feb 2023 23:50:34 +0530
From:   Sunil V L <sunilvl@...tanamicro.com>
To:     Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>, Jonathan Corbet <corbet@....net>
Cc:     linux-riscv@...ts.infradead.org, linux-acpi@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Conor Dooley <conor.dooley@...rochip.com>,
        Andrew Jones <ajones@...tanamicro.com>,
        Anup Patel <apatel@...tanamicro.com>,
        Atish Patra <atishp@...osinc.com>,
        Sunil V L <sunilvl@...tanamicro.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH V2 12/21] RISC-V: cpufeature: Add ACPI support in riscv_fill_hwcap()

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@...tanamicro.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 arch/riscv/kernel/cpufeature.c | 41 ++++++++++++++++++++++++++++------
 1 file changed, 34 insertions(+), 7 deletions(-)

diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 93e45560af30..cb67d3fcbb56 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -6,12 +6,15 @@
  * 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 <linux/of_device.h>
+#include <asm/acpi.h>
 #include <asm/alternative.h>
 #include <asm/cacheflush.h>
 #include <asm/errata_list.h>
@@ -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 +112,36 @@ 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;
+		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);
+				continue;
+			}
 		}
 
 		temp = isa;
@@ -248,6 +272,9 @@ void __init riscv_fill_hwcap(void)
 			bitmap_and(riscv_isa, riscv_isa, this_isa, RISCV_ISA_EXT_MAX);
 	}
 
+	if (!acpi_disabled)
+		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