1 files changed, 151 insertions, 0 deletions
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
new file mode 100644
index 000000000..ac202f44a
--- /dev/null
+++ b/arch/riscv/kernel/cpufeature.c
@@ -0,0 +1,151 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copied from arch/arm64/kernel/cpufeature.c
+ *
+ * Copyright (C) 2015 ARM Ltd.
+ * Copyright (C) 2017 SiFive
+ */
+
+#include <linux/bitmap.h>
+#include <linux/of.h>
+#include <asm/processor.h>
+#include <asm/hwcap.h>
+#include <asm/smp.h>
+#include <asm/switch_to.h>
+
+unsigned long elf_hwcap __read_mostly;
+
+/* Host ISA bitmap */
+static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly;
+
+#ifdef CONFIG_FPU
+bool has_fpu __read_mostly;
+#endif
+
+/**
+ * riscv_isa_extension_base() - Get base extension word
+ *
+ * @isa_bitmap: ISA bitmap to use
+ * Return: base extension word as unsigned long value
+ *
+ * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
+ */
+unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap)
+{
+	if (!isa_bitmap)
+		return riscv_isa[0];
+	return isa_bitmap[0];
+}
+EXPORT_SYMBOL_GPL(riscv_isa_extension_base);
+
+/**
+ * __riscv_isa_extension_available() - Check whether given extension
+ * is available or not
+ *
+ * @isa_bitmap: ISA bitmap to use
+ * @bit: bit position of the desired extension
+ * Return: true or false
+ *
+ * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
+ */
+bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit)
+{
+	const unsigned long *bmap = (isa_bitmap) ? isa_bitmap : riscv_isa;
+
+	if (bit >= RISCV_ISA_EXT_MAX)
+		return false;
+
+	return test_bit(bit, bmap) ? true : false;
+}
+EXPORT_SYMBOL_GPL(__riscv_isa_extension_available);
+
+void riscv_fill_hwcap(void)
+{
+	struct device_node *node;
+	const char *isa;
+	char print_str[BITS_PER_LONG + 1];
+	size_t i, j, isa_len;
+	static unsigned long isa2hwcap[256] = {0};
+
+	isa2hwcap['i'] = isa2hwcap['I'] = COMPAT_HWCAP_ISA_I;
+	isa2hwcap['m'] = isa2hwcap['M'] = COMPAT_HWCAP_ISA_M;
+	isa2hwcap['a'] = isa2hwcap['A'] = COMPAT_HWCAP_ISA_A;
+	isa2hwcap['f'] = isa2hwcap['F'] = COMPAT_HWCAP_ISA_F;
+	isa2hwcap['d'] = isa2hwcap['D'] = COMPAT_HWCAP_ISA_D;
+	isa2hwcap['c'] = isa2hwcap['C'] = COMPAT_HWCAP_ISA_C;
+
+	elf_hwcap = 0;
+
+	bitmap_zero(riscv_isa, RISCV_ISA_EXT_MAX);
+
+	for_each_of_cpu_node(node) {
+		unsigned long this_hwcap = 0;
+		unsigned long this_isa = 0;
+
+		if (riscv_of_processor_hartid(node) < 0)
+			continue;
+
+		if (of_property_read_string(node, "riscv,isa", &isa)) {
+			pr_warn("Unable to find \"riscv,isa\" devicetree entry\n");
+			continue;
+		}
+
+		i = 0;
+		isa_len = strlen(isa);
+#if IS_ENABLED(CONFIG_32BIT)
+		if (!strncmp(isa, "rv32", 4))
+			i += 4;
+#elif IS_ENABLED(CONFIG_64BIT)
+		if (!strncmp(isa, "rv64", 4))
+			i += 4;
+#endif
+		for (; i < isa_len; ++i) {
+			this_hwcap |= isa2hwcap[(unsigned char)(isa[i])];
+			/*
+			 * TODO: X, Y and Z extension parsing for Host ISA
+			 * bitmap will be added in-future.
+			 */
+			if ('a' <= isa[i] && isa[i] < 'x')
+				this_isa |= (1UL << (isa[i] - 'a'));
+		}
+
+		/*
+		 * All "okay" hart should have same isa. Set HWCAP based on
+		 * common capabilities of every "okay" hart, in case they don't
+		 * have.
+		 */
+		if (elf_hwcap)
+			elf_hwcap &= this_hwcap;
+		else
+			elf_hwcap = this_hwcap;
+
+		if (riscv_isa[0])
+			riscv_isa[0] &= this_isa;
+		else
+			riscv_isa[0] = this_isa;
+	}
+
+	/* 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)) {
+		pr_info("This kernel does not support systems with F but not D\n");
+		elf_hwcap &= ~COMPAT_HWCAP_ISA_F;
+	}
+
+	memset(print_str, 0, sizeof(print_str));
+	for (i = 0, j = 0; i < BITS_PER_LONG; i++)
+		if (riscv_isa[0] & BIT_MASK(i))
+			print_str[j++] = (char)('a' + i);
+	pr_info("riscv: ISA extensions %s\n", print_str);
+
+	memset(print_str, 0, sizeof(print_str));
+	for (i = 0, j = 0; i < BITS_PER_LONG; i++)
+		if (elf_hwcap & BIT_MASK(i))
+			print_str[j++] = (char)('a' + i);
+	pr_info("riscv: ELF capabilities %s\n", print_str);
+
+#ifdef CONFIG_FPU
+	if (elf_hwcap & (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D))
+		has_fpu = true;
+#endif
+}