lib: sbi: Detect Smstateen CSRs at boot-time

Extend HART feature detection to discover Smstateen CSRs at boot-time
and configure mstateen envcfg bit depending on availability of
menvcfg CSR.

Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
Reviewed-by: Xiang W <wxjstz@126.com>
Reviewed-by: Anup Patel <anup@brainfault.org>

diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
index 57f80bc..be3ad9f 100644 (file)
--- a/include/sbi/sbi_hart.h
+++ b/include/sbi/sbi_hart.h
@@ -28,9 +28,11 @@ enum sbi_hart_features {
        SBI_HART_HAS_AIA = (1 << 5),
        /** HART has menvcfg CSR */
        SBI_HART_HAS_MENVCFG = (1 << 6),
+       /** HART has mstateen CSR **/
+       SBI_HART_HAS_SMSTATEEN = (1 << 7),
 
        /** Last index of Hart features*/
-       SBI_HART_HAS_LAST_FEATURE = SBI_HART_HAS_MENVCFG,
+       SBI_HART_HAS_LAST_FEATURE = SBI_HART_HAS_SMSTATEEN,
 };
 
 struct sbi_scratch;

diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
index 6be9286..b0edf38 100644 (file)
--- a/lib/sbi/sbi_hart.c
+++ b/lib/sbi/sbi_hart.c
@@ -43,6 +43,7 @@ static void mstatus_init(struct sbi_scratch *scratch)
        int cidx;
        unsigned int num_mhpm = sbi_hart_mhpm_count(scratch);
        uint64_t mhpmevent_init_val = 0;
+       uint64_t mstateen_val;
 
        /* Enable FPU */
        if (misa_extension('D') || misa_extension('F'))
@@ -87,6 +88,22 @@ static void mstatus_init(struct sbi_scratch *scratch)
 #endif
        }
 
+       if (sbi_hart_has_feature(scratch, SBI_HART_HAS_SMSTATEEN)) {
+               mstateen_val = csr_read(CSR_MSTATEEN0);
+#if __riscv_xlen == 32
+               mstateen_val |= ((uint64_t)csr_read(CSR_MSTATEEN0H)) << 32;
+#endif
+               mstateen_val |= SMSTATEEN_STATEN;
+               if (sbi_hart_has_feature(scratch, SBI_HART_HAS_MENVCFG))
+                       mstateen_val |= SMSTATEEN0_HSENVCFG;
+               else
+                       mstateen_val &= ~SMSTATEEN0_HSENVCFG;
+               csr_write(CSR_MSTATEEN0, mstateen_val);
+#if __riscv_xlen == 32
+               csr_write(CSR_MSTATEEN0H, mstateen_val >> 32);
+#endif
+       }
+
        if (sbi_hart_has_feature(scratch, SBI_HART_HAS_MENVCFG)) {
                menvcfg_val = csr_read(CSR_MENVCFG);
 
@@ -348,6 +365,9 @@ static inline char *sbi_hart_feature_id2string(unsigned long feature)
        case SBI_HART_HAS_MENVCFG:
                fstr = "menvcfg";
                break;
+       case SBI_HART_HAS_SMSTATEEN:
+               fstr = "smstateen";
+               break;
        default:
                break;
        }
@@ -584,6 +604,11 @@ __aia_skip:
        if (!trap.cause)
                hfeatures->features |= SBI_HART_HAS_MENVCFG;
 
+       /* Detect if hart supports mstateen CSRs */
+       val = csr_read_allowed(CSR_MSTATEEN0, (unsigned long)&trap);
+       if (!trap.cause)
+               hfeatures->features |= SBI_HART_HAS_SMSTATEEN;
+
        return;
 }