lib: sbi: Add Smrnmi extension macros for registers and bits

Add CSR definitions (MNSCRATCH, MNSTATUS, MNEPC, MNCAUSE) and bit definitions
(MNSTATUS_NMIE, MNSTATUS_MNPV, MNSTATUS_MNPP). Also add SBI_HART_EXT_SMRNMI to
the hart extension enumeration.

Signed-off-by: Evgeny Voevodin <evvoevod@tenstorrent.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/1c6feb6d359b9827b3c2ad8f4f0e0a4dfd1de911.1778176768.git.evvoevod@tenstorrent.com
Signed-off-by: Anup Patel <anup@brainfault.org>

include/sbi/riscv_encoding.h

@@ -215,6 +215,10 @@
 
 #endif
 
+#define MNSTATUS_NMIE			(_UL(0x8))
+#define MNSTATUS_MNPV			(_UL(0x80))
+#define MNSTATUS_MNPP			(_UL(0x1800))
+
 #define MHPMEVENT_SSCOF_MASK		_ULL(0xFF00000000000000)
 
 #define ENVCFG_STCE			(_ULL(1) << 63)
@@ -830,6 +834,12 @@
 #define CSR_CUSTOM10_M_RO_BASE		0xFC0
 #define CSR_CUSTOM10_M_RO_COUNT		0x040
 
+/* Smrnmi extension registers */
+#define CSR_MNSCRATCH				0x740
+#define CSR_MNEPC					0x741
+#define CSR_MNCAUSE					0x742
+#define CSR_MNSTATUS				0x744
+
 /* ===== Trap/Exception Causes ===== */
 
 #define CAUSE_MISALIGNED_FETCH		0x0

include/sbi/sbi_hart.h

@@ -87,6 +87,8 @@ enum sbi_hart_extensions {
 	SBI_HART_EXT_XSIFIVE_CFLUSH_D_L1,
 	/** Hart has Xsfcease extension */
 	SBI_HART_EXT_XSIFIVE_CEASE,
+	/** Hart has Smrnmi extension */
+	SBI_HART_EXT_SMRNMI,
 
 	/** Maximum index of Hart extension */
 	SBI_HART_EXT_MAX,

lib/sbi/sbi_hart.c

@@ -396,6 +396,7 @@ const struct sbi_hart_ext_data sbi_hart_ext[] = {
 	__SBI_HART_EXT_DATA(ssstateen, SBI_HART_EXT_SSSTATEEN),
 	__SBI_HART_EXT_DATA(xsfcflushdlone, SBI_HART_EXT_XSIFIVE_CFLUSH_D_L1),
 	__SBI_HART_EXT_DATA(xsfcease, SBI_HART_EXT_XSIFIVE_CEASE),
+	__SBI_HART_EXT_DATA(smrnmi, SBI_HART_EXT_SMRNMI),
 };
 
 _Static_assert(SBI_HART_EXT_MAX == array_size(sbi_hart_ext),