lib: sbi: Detect menvcfg CSR at boot time

We add the menvcfg CSR as a HART feature and detect it at boot time
using traping mechanism.

Signed-off-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Xiang W <wxjstz@126.com>

diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
index a83b45b..57f80bc 100644 (file)
--- a/include/sbi/sbi_hart.h
+++ b/include/sbi/sbi_hart.h
@@ -26,9 +26,11 @@ enum sbi_hart_features {
        SBI_HART_HAS_TIME = (1 << 4),
        /** HART has AIA local interrupt CSRs */
        SBI_HART_HAS_AIA = (1 << 5),
+       /** HART has menvcfg CSR */
+       SBI_HART_HAS_MENVCFG = (1 << 6),
 
        /** Last index of Hart features*/
-       SBI_HART_HAS_LAST_FEATURE = SBI_HART_HAS_AIA,
+       SBI_HART_HAS_LAST_FEATURE = SBI_HART_HAS_MENVCFG,
 };
 
 struct sbi_scratch;

diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
index e028540..31c8f39 100644 (file)
--- a/lib/sbi/sbi_hart.c
+++ b/lib/sbi/sbi_hart.c
@@ -304,6 +304,9 @@ static inline char *sbi_hart_feature_id2string(unsigned long feature)
        case SBI_HART_HAS_AIA:
                fstr = "aia";
                break;
+       case SBI_HART_HAS_MENVCFG:
+               fstr = "menvcfg";
+               break;
        default:
                break;
        }
@@ -534,6 +537,12 @@ __mhpm_skip:
                goto __aia_skip;
        hfeatures->features |= SBI_HART_HAS_AIA;
 __aia_skip:
+
+       /* Detect if hart has menvcfg CSR */
+       csr_read_allowed(CSR_MENVCFG, (unsigned long)&trap);
+       if (!trap.cause)
+               hfeatures->features |= SBI_HART_HAS_MENVCFG;
+
        return;
 }