RISC-V: split riscv_fill_hwcap() in 3

Before adding more complexity to it, split riscv_fill_hwcap() into 3
distinct sections:
- riscv_fill_hwcap() still is the top level function, into which the
  additional complexity will be added.
- riscv_fill_hwcap_from_isa_string() handles getting the information
  from the riscv,isa/ACPI equivalent across harts & the various quirks
  there
- riscv_parse_isa_string() does what it says on the tin.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230713-daylight-puritan-37aeb41a4d9b@wendySigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/kernel/cpufeature.c

@@ -178,60 +178,9 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
 
 const size_t riscv_isa_ext_count = ARRAY_SIZE(riscv_isa_ext);
 
-void __init riscv_fill_hwcap(void)
+static void __init riscv_parse_isa_string(unsigned long *this_hwcap, struct riscv_isainfo *isainfo,
+					  unsigned long *isa2hwcap, const char *isa)
 {
-	struct device_node *node;
-	const char *isa;
-	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 int cpu;
-
-	isa2hwcap['i' - 'a'] = COMPAT_HWCAP_ISA_I;
-	isa2hwcap['m' - 'a'] = COMPAT_HWCAP_ISA_M;
-	isa2hwcap['a' - 'a'] = COMPAT_HWCAP_ISA_A;
-	isa2hwcap['f' - 'a'] = COMPAT_HWCAP_ISA_F;
-	isa2hwcap['d' - 'a'] = COMPAT_HWCAP_ISA_D;
-	isa2hwcap['c' - 'a'] = COMPAT_HWCAP_ISA_C;
-	isa2hwcap['v' - 'a'] = COMPAT_HWCAP_ISA_V;
-
-	elf_hwcap = 0;
-
-	bitmap_zero(riscv_isa, RISCV_ISA_EXT_MAX);
-
-	if (!acpi_disabled) {
-		status = acpi_get_table(ACPI_SIG_RHCT, 0, &rhct);
-		if (ACPI_FAILURE(status))
-			return;
-	}
-
-	for_each_possible_cpu(cpu) {
-		struct riscv_isainfo *isainfo = &hart_isa[cpu];
-		unsigned long this_hwcap = 0;
-
-		if (acpi_disabled) {
-			node = of_cpu_device_node_get(cpu);
-			if (!node) {
-				pr_warn("Unable to find cpu node\n");
-				continue;
-			}
-
-			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, cpu, &isa);
-			if (rc < 0) {
-				pr_warn("Unable to get ISA for the hart - %d\n", cpu);
-				continue;
-			}
-		}
-
 	/*
 	 * For all possible cpus, we have already validated in
 	 * the boot process that they at least contain "rv" and
@@ -374,7 +323,7 @@ void __init riscv_fill_hwcap(void)
 			int nr = tolower(*ext) - 'a';
 
 			if (riscv_isa_extension_check(nr)) {
-					this_hwcap |= isa2hwcap[nr];
+				*this_hwcap |= isa2hwcap[nr];
 				set_bit(nr, isainfo->isa);
 			}
 		} else {
@@ -384,6 +333,49 @@ void __init riscv_fill_hwcap(void)
 		}
 #undef SET_ISA_EXT_MAP
 	}
+}
+
+static void __init riscv_fill_hwcap_from_isa_string(unsigned long *isa2hwcap)
+{
+	struct device_node *node;
+	const char *isa;
+	int rc;
+	struct acpi_table_header *rhct;
+	acpi_status status;
+	unsigned int cpu;
+
+	if (!acpi_disabled) {
+		status = acpi_get_table(ACPI_SIG_RHCT, 0, &rhct);
+		if (ACPI_FAILURE(status))
+			return;
+	}
+
+	for_each_possible_cpu(cpu) {
+		struct riscv_isainfo *isainfo = &hart_isa[cpu];
+		unsigned long this_hwcap = 0;
+
+		if (acpi_disabled) {
+			node = of_cpu_device_node_get(cpu);
+			if (!node) {
+				pr_warn("Unable to find cpu node\n");
+				continue;
+			}
+
+			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, cpu, &isa);
+			if (rc < 0) {
+				pr_warn("Unable to get ISA for the hart - %d\n", cpu);
+				continue;
+			}
+		}
+
+		riscv_parse_isa_string(&this_hwcap, isainfo, isa2hwcap, isa);
 
 		/*
 		 * Linux requires the following extensions, so we may as well
@@ -420,6 +412,23 @@ void __init riscv_fill_hwcap(void)
 
 	if (!acpi_disabled && rhct)
 		acpi_put_table((struct acpi_table_header *)rhct);
+}
+
+void __init riscv_fill_hwcap(void)
+{
+	char print_str[NUM_ALPHA_EXTS + 1];
+	int i, j;
+	unsigned long isa2hwcap[26] = {0};
+
+	isa2hwcap['i' - 'a'] = COMPAT_HWCAP_ISA_I;
+	isa2hwcap['m' - 'a'] = COMPAT_HWCAP_ISA_M;
+	isa2hwcap['a' - 'a'] = COMPAT_HWCAP_ISA_A;
+	isa2hwcap['f' - 'a'] = COMPAT_HWCAP_ISA_F;
+	isa2hwcap['d' - 'a'] = COMPAT_HWCAP_ISA_D;
+	isa2hwcap['c' - 'a'] = COMPAT_HWCAP_ISA_C;
+	isa2hwcap['v' - 'a'] = COMPAT_HWCAP_ISA_V;
+
+	riscv_fill_hwcap_from_isa_string(isa2hwcap);
 
 	/* We don't support systems with F but without D, so mask those out
 	 * here. */