riscv: Enhance extension probing

Enhance the existing extension probing mechanism by adding support for
more extensions and probing using the "riscv,isa" property. This patch
is ported from the latest upstream linux.

Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
new file mode 100644
index 0000000..aa68ada
--- /dev/null
+++ b/arch/riscv/include/asm/hwcap.h
@@ -0,0 +1,105 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _ASM_RISCV_HWCAP_H
+#define _ASM_RISCV_HWCAP_H
+
+#define RISCV_ISA_EXT_a		('a' - 'a')
+#define RISCV_ISA_EXT_c		('c' - 'a')
+#define RISCV_ISA_EXT_d		('d' - 'a')
+#define RISCV_ISA_EXT_f		('f' - 'a')
+#define RISCV_ISA_EXT_h		('h' - 'a')
+#define RISCV_ISA_EXT_i		('i' - 'a')
+#define RISCV_ISA_EXT_m		('m' - 'a')
+#define RISCV_ISA_EXT_q		('q' - 'a')
+#define RISCV_ISA_EXT_v		('v' - 'a')
+
+/*
+ * These macros represent the logical IDs of each multi-letter RISC-V ISA
+ * extension and are used in the ISA bitmap. The logical IDs start from
+ * RISCV_ISA_EXT_BASE, which allows the 0-25 range to be reserved for single
+ * letter extensions. The maximum, RISCV_ISA_EXT_MAX, is defined in order
+ * to allocate the bitmap and may be increased when necessary.
+ *
+ * New extensions should just be added to the bottom, rather than added
+ * alphabetically, in order to avoid unnecessary shuffling.
+ */
+#define RISCV_ISA_EXT_BASE		26
+
+#define RISCV_ISA_EXT_SSCOFPMF		26
+#define RISCV_ISA_EXT_SSTC		27
+#define RISCV_ISA_EXT_SVINVAL		28
+#define RISCV_ISA_EXT_SVPBMT		29
+#define RISCV_ISA_EXT_ZBB		30
+#define RISCV_ISA_EXT_ZICBOM		31
+#define RISCV_ISA_EXT_ZIHINTPAUSE	32
+#define RISCV_ISA_EXT_SVNAPOT		33
+#define RISCV_ISA_EXT_ZICBOZ		34
+#define RISCV_ISA_EXT_SMAIA		35
+#define RISCV_ISA_EXT_SSAIA		36
+#define RISCV_ISA_EXT_ZBA		37
+#define RISCV_ISA_EXT_ZBS		38
+#define RISCV_ISA_EXT_ZICNTR		39
+#define RISCV_ISA_EXT_ZICSR		40
+#define RISCV_ISA_EXT_ZIFENCEI		41
+#define RISCV_ISA_EXT_ZIHPM		42
+#define RISCV_ISA_EXT_SMSTATEEN		43
+#define RISCV_ISA_EXT_ZICOND		44
+#define RISCV_ISA_EXT_ZBC		45
+#define RISCV_ISA_EXT_ZBKB		46
+#define RISCV_ISA_EXT_ZBKC		47
+#define RISCV_ISA_EXT_ZBKX		48
+#define RISCV_ISA_EXT_ZKND		49
+#define RISCV_ISA_EXT_ZKNE		50
+#define RISCV_ISA_EXT_ZKNH		51
+#define RISCV_ISA_EXT_ZKR		52
+#define RISCV_ISA_EXT_ZKSED		53
+#define RISCV_ISA_EXT_ZKSH		54
+#define RISCV_ISA_EXT_ZKT		55
+#define RISCV_ISA_EXT_ZVBB		56
+#define RISCV_ISA_EXT_ZVBC		57
+#define RISCV_ISA_EXT_ZVKB		58
+#define RISCV_ISA_EXT_ZVKG		59
+#define RISCV_ISA_EXT_ZVKNED		60
+#define RISCV_ISA_EXT_ZVKNHA		61
+#define RISCV_ISA_EXT_ZVKNHB		62
+#define RISCV_ISA_EXT_ZVKSED		63
+#define RISCV_ISA_EXT_ZVKSH		64
+#define RISCV_ISA_EXT_ZVKT		65
+#define RISCV_ISA_EXT_ZFH		66
+#define RISCV_ISA_EXT_ZFHMIN		67
+#define RISCV_ISA_EXT_ZIHINTNTL		68
+#define RISCV_ISA_EXT_ZVFH		69
+#define RISCV_ISA_EXT_ZVFHMIN		70
+#define RISCV_ISA_EXT_ZFA		71
+#define RISCV_ISA_EXT_ZTSO		72
+#define RISCV_ISA_EXT_ZACAS		73
+#define RISCV_ISA_EXT_ZVE32X		74
+#define RISCV_ISA_EXT_ZVE32F		75
+#define RISCV_ISA_EXT_ZVE64X		76
+#define RISCV_ISA_EXT_ZVE64F		77
+#define RISCV_ISA_EXT_ZVE64D		78
+#define RISCV_ISA_EXT_ZIMOP		79
+#define RISCV_ISA_EXT_ZCA		80
+#define RISCV_ISA_EXT_ZCB		81
+#define RISCV_ISA_EXT_ZCD		82
+#define RISCV_ISA_EXT_ZCF		83
+#define RISCV_ISA_EXT_ZCMOP		84
+#define RISCV_ISA_EXT_ZAWRS		85
+#define RISCV_ISA_EXT_SVVPTC		86
+#define RISCV_ISA_EXT_SMMPM		87
+#define RISCV_ISA_EXT_SMNPM		88
+#define RISCV_ISA_EXT_SSNPM		89
+
+#define RISCV_ISA_EXT_XLINUXENVCFG	127
+
+#define RISCV_ISA_EXT_MAX		128
+#define RISCV_ISA_EXT_INVALID		U32_MAX
+
+#ifdef CONFIG_RISCV_M_MODE
+#define RISCV_ISA_EXT_SxAIA		RISCV_ISA_EXT_SMAIA
+#define RISCV_ISA_EXT_SUPM		RISCV_ISA_EXT_SMNPM
+#else
+#define RISCV_ISA_EXT_SxAIA		RISCV_ISA_EXT_SSAIA
+#define RISCV_ISA_EXT_SUPM		RISCV_ISA_EXT_SSNPM
+#endif
+
+#endif /* _ASM_RISCV_HWCAP_H */