lib: sbi: Remove MCOUNTINHIBT hart feature

If a hart implements privileged spec v1.11 (or higher) then we can
safely assume that mcountinhibit CSR is present and we don't need
MCOUNTINHIBT as a hart feature.

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

3 files changed, 19 insertions, 28 deletions

diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
index 4665a62..bc6b766 100644
--- a/include/sbi/sbi_hart.h
+++ b/include/sbi/sbi_hart.h
@@ -26,20 +26,18 @@ enum sbi_hart_priv_versions {
 
 /** Possible feature flags of a hart */
 enum sbi_hart_features {
-	/** Hart has counter inhibit CSR */
-	SBI_HART_HAS_MCOUNTINHIBIT = (1 << 0),
 	/** Hart has sscofpmf extension */
-	SBI_HART_HAS_SSCOFPMF = (1 << 1),
+	SBI_HART_HAS_SSCOFPMF = (1 << 0),
 	/** HART has timer csr implementation in hardware */
-	SBI_HART_HAS_TIME = (1 << 2),
+	SBI_HART_HAS_TIME = (1 << 1),
 	/** HART has AIA local interrupt CSRs */
-	SBI_HART_HAS_AIA = (1 << 3),
+	SBI_HART_HAS_AIA = (1 << 2),
 	/** HART has menvcfg CSR */
-	SBI_HART_HAS_MENVCFG = (1 << 4),
+	SBI_HART_HAS_MENVCFG = (1 << 3),
 	/** HART has mstateen CSR **/
-	SBI_HART_HAS_SMSTATEEN = (1 << 5),
+	SBI_HART_HAS_SMSTATEEN = (1 << 4),
 	/** HART has SSTC extension implemented in hardware */
-	SBI_HART_HAS_SSTC = (1 << 6),
+	SBI_HART_HAS_SSTC = (1 << 5),
 
 	/** Last index of Hart features*/
 	SBI_HART_HAS_LAST_FEATURE = SBI_HART_HAS_SSTC,
diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
index ed8a061..0fe88cb 100644
--- a/lib/sbi/sbi_hart.c
+++ b/lib/sbi/sbi_hart.c
@@ -70,7 +70,7 @@ static void mstatus_init(struct sbi_scratch *scratch)
 		csr_write(CSR_MCOUNTEREN, -1);
 
 	/* All programmable counters will start running at runtime after S-mode request */
-	if (sbi_hart_has_feature(scratch, SBI_HART_HAS_MCOUNTINHIBIT))
+	if (sbi_hart_priv_version(scratch) >= SBI_HART_PRIV_VER_1_11)
 		csr_write(CSR_MCOUNTINHIBIT, 0xFFFFFFF8);
 
 	/**
@@ -402,9 +402,6 @@ static inline char *sbi_hart_feature_id2string(unsigned long feature)
 		return NULL;
 
 	switch (feature) {
-	case SBI_HART_HAS_MCOUNTINHIBIT:
-		fstr = "mcountinhibit";
-		break;
 	case SBI_HART_HAS_SSCOFPMF:
 		fstr = "sscofpmf";
 		break;
@@ -613,26 +610,22 @@ __mhpm_skip:
 	if (!trap.cause)
 		hfeatures->priv_version = SBI_HART_PRIV_VER_1_10;
 
-	/* Detect if hart supports MCOUNTINHIBIT feature */
+	/* Detect if hart supports Priv v1.11 */
 	val = csr_read_allowed(CSR_MCOUNTINHIBIT, (unsigned long)&trap);
-	if (!trap.cause) {
-		csr_write_allowed(CSR_MCOUNTINHIBIT, (unsigned long)&trap, val);
-		if (!trap.cause) {
-			hfeatures->priv_version = SBI_HART_PRIV_VER_1_11;
-			hfeatures->features |= SBI_HART_HAS_MCOUNTINHIBIT;
-		}
-	}
+	if (!trap.cause &&
+	    (hfeatures->priv_version >= SBI_HART_PRIV_VER_1_10))
+		hfeatures->priv_version = SBI_HART_PRIV_VER_1_11;
 
 	/* Detect if hart has menvcfg CSR */
 	csr_read_allowed(CSR_MENVCFG, (unsigned long)&trap);
-	if (!trap.cause) {
+	if (!trap.cause &&
+	    (hfeatures->priv_version >= SBI_HART_PRIV_VER_1_11)) {
 		hfeatures->priv_version = SBI_HART_PRIV_VER_1_12;
 		hfeatures->features |= SBI_HART_HAS_MENVCFG;
 	}
 
 	/* Counter overflow/filtering is not useful without mcounter/inhibit */
-	if (hfeatures->features & SBI_HART_HAS_MCOUNTINHIBIT &&
-	    hfeatures->priv_version >= SBI_HART_PRIV_VER_1_12) {
+	if (hfeatures->priv_version >= SBI_HART_PRIV_VER_1_12) {
 		/* Detect if hart supports sscofpmf */
 		csr_read_allowed(CSR_SCOUNTOVF, (unsigned long)&trap);
 		if (!trap.cause)
diff --git a/lib/sbi/sbi_pmu.c b/lib/sbi/sbi_pmu.c
index 1b8f1cf..f0a88ca 100644
--- a/lib/sbi/sbi_pmu.c
+++ b/lib/sbi/sbi_pmu.c
@@ -300,7 +300,7 @@ static int pmu_ctr_start_hw(uint32_t cidx, uint64_t ival, bool ival_update)
 	if (cidx > num_hw_ctrs || cidx == 1)
 		return SBI_EINVAL;
 
-	if (!sbi_hart_has_feature(scratch, SBI_HART_HAS_MCOUNTINHIBIT))
+	if (sbi_hart_priv_version(scratch) < SBI_HART_PRIV_VER_1_11)
 		goto skip_inhibit_update;
 
 	/*
@@ -372,7 +372,7 @@ static int pmu_ctr_stop_hw(uint32_t cidx)
 	struct sbi_scratch *scratch = sbi_scratch_thishart_ptr();
 	unsigned long mctr_inhbt;
 
-	if (!sbi_hart_has_feature(scratch, SBI_HART_HAS_MCOUNTINHIBIT))
+	if (sbi_hart_priv_version(scratch) < SBI_HART_PRIV_VER_1_11)
 		return 0;
 
 	mctr_inhbt = csr_read(CSR_MCOUNTINHIBIT);
@@ -528,7 +528,7 @@ static int pmu_ctr_find_hw(unsigned long cbase, unsigned long cmask, unsigned lo
 	    !sbi_hart_has_feature(scratch, SBI_HART_HAS_SSCOFPMF))
 		return fixed_ctr;
 
-	if (sbi_hart_has_feature(scratch, SBI_HART_HAS_MCOUNTINHIBIT))
+	if (sbi_hart_priv_version(scratch) >= SBI_HART_PRIV_VER_1_11)
 		mctr_inhbt = csr_read(CSR_MCOUNTINHIBIT);
 	for (i = 0; i < num_hw_events; i++) {
 		temp = &hw_event_map[i];
@@ -555,7 +555,7 @@ static int pmu_ctr_find_hw(unsigned long cbase, unsigned long cmask, unsigned lo
 			if (active_events[hartid][cbase] != SBI_PMU_EVENT_IDX_INVALID)
 				continue;
 			/* If mcountinhibit is supported, the bit must be enabled */
-			if ((sbi_hart_has_feature(scratch, SBI_HART_HAS_MCOUNTINHIBIT)) &&
+			if ((sbi_hart_priv_version(scratch) >= SBI_HART_PRIV_VER_1_11) &&
 			    !__test_bit(cbase, &mctr_inhbt))
 				continue;
 			/* We found a valid counter that is not started yet */
@@ -730,7 +730,7 @@ void sbi_pmu_exit(struct sbi_scratch *scratch)
 {
 	u32 hartid = current_hartid();
 
-	if (sbi_hart_has_feature(scratch, SBI_HART_HAS_MCOUNTINHIBIT))
+	if (sbi_hart_priv_version(scratch) >= SBI_HART_PRIV_VER_1_11)
 		csr_write(CSR_MCOUNTINHIBIT, 0xFFFFFFF8);
 
 	if (sbi_hart_priv_version(scratch) >= SBI_HART_PRIV_VER_1_10)