lib: sbi: Detect and print privileged spec version

It is possible to guess privileged spec versions based on the CSRs
that where introduced in different privileged spec versions. In
future, if we are not able guess privileged spec version then we
can have platform provide it.

We add privileged spec version as per-hart feature and try to guess
it based on presence of mcounteren, mcountinhibit, and menvcfg CSRs.

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

3 files changed, 63 insertions, 6 deletions

diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
index 1d09374..3c37933 100644
--- a/include/sbi/sbi_hart.h
+++ b/include/sbi/sbi_hart.h
@@ -12,6 +12,18 @@
 
 #include <sbi/sbi_types.h>
 
+/** Possible privileged specification versions of a hart */
+enum sbi_hart_priv_versions {
+	/** Unknown privileged specification */
+	SBI_HART_PRIV_VER_UNKNOWN = 0,
+	/** Privileged specification v1.10 */
+	SBI_HART_PRIV_VER_1_10 = 1,
+	/** Privileged specification v1.11 */
+	SBI_HART_PRIV_VER_1_11 = 2,
+	/** Privileged specification v1.12 */
+	SBI_HART_PRIV_VER_1_12 = 3,
+};
+
 /** Possible feature flags of a hart */
 enum sbi_hart_features {
 	/** Hart has S-mode counter enable */
@@ -56,6 +68,9 @@ unsigned long sbi_hart_pmp_granularity(struct sbi_scratch *scratch);
 unsigned int sbi_hart_pmp_addrbits(struct sbi_scratch *scratch);
 unsigned int sbi_hart_mhpm_bits(struct sbi_scratch *scratch);
 int sbi_hart_pmp_configure(struct sbi_scratch *scratch);
+int sbi_hart_priv_version(struct sbi_scratch *scratch);
+void sbi_hart_get_priv_version_str(struct sbi_scratch *scratch,
+				   char *version_str, int nvstr);
 bool sbi_hart_has_feature(struct sbi_scratch *scratch, unsigned long feature);
 void sbi_hart_get_features_str(struct sbi_scratch *scratch,
 			       char *features_str, int nfstr);
diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
index 229c14a..ed4e631 100644
--- a/lib/sbi/sbi_hart.c
+++ b/lib/sbi/sbi_hart.c
@@ -28,6 +28,7 @@ extern void __sbi_expected_trap_hext(void);
 void (*sbi_hart_expected_trap)(void) = &__sbi_expected_trap;
 
 struct hart_features {
+	int priv_version;
 	unsigned long features;
 	unsigned int pmp_count;
 	unsigned int pmp_addr_bits;
@@ -334,6 +335,39 @@ int sbi_hart_pmp_configure(struct sbi_scratch *scratch)
 	return 0;
 }
 
+int sbi_hart_priv_version(struct sbi_scratch *scratch)
+{
+	struct hart_features *hfeatures =
+			sbi_scratch_offset_ptr(scratch, hart_features_offset);
+
+	return hfeatures->priv_version;
+}
+
+void sbi_hart_get_priv_version_str(struct sbi_scratch *scratch,
+				   char *version_str, int nvstr)
+{
+	char *temp;
+	struct hart_features *hfeatures =
+			sbi_scratch_offset_ptr(scratch, hart_features_offset);
+
+	switch (hfeatures->priv_version) {
+	case SBI_HART_PRIV_VER_1_10:
+		temp = "v1.10";
+		break;
+	case SBI_HART_PRIV_VER_1_11:
+		temp = "v1.11";
+		break;
+	case SBI_HART_PRIV_VER_1_12:
+		temp = "v1.12";
+		break;
+	default:
+		temp = "unknown";
+		break;
+	}
+
+	sbi_snprintf(version_str, nvstr, "%s", temp);
+}
+
 /**
  * Check whether a particular hart feature is available
  *
@@ -583,6 +617,7 @@ __mhpm_skip:
 	/* Detect if hart supports SCOUNTEREN feature */
 	val = csr_read_allowed(CSR_SCOUNTEREN, (unsigned long)&trap);
 	if (!trap.cause) {
+		hfeatures->priv_version = SBI_HART_PRIV_VER_1_10;
 		csr_write_allowed(CSR_SCOUNTEREN, (unsigned long)&trap, val);
 		if (!trap.cause)
 			hfeatures->features |= SBI_HART_HAS_SCOUNTEREN;
@@ -591,6 +626,7 @@ __mhpm_skip:
 	/* Detect if hart supports MCOUNTEREN feature */
 	val = csr_read_allowed(CSR_MCOUNTEREN, (unsigned long)&trap);
 	if (!trap.cause) {
+		hfeatures->priv_version = SBI_HART_PRIV_VER_1_10;
 		csr_write_allowed(CSR_MCOUNTEREN, (unsigned long)&trap, val);
 		if (!trap.cause)
 			hfeatures->features |= SBI_HART_HAS_MCOUNTEREN;
@@ -600,8 +636,17 @@ __mhpm_skip:
 	val = csr_read_allowed(CSR_MCOUNTINHIBIT, (unsigned long)&trap);
 	if (!trap.cause) {
 		csr_write_allowed(CSR_MCOUNTINHIBIT, (unsigned long)&trap, val);
-		if (!trap.cause)
+		if (!trap.cause) {
+			hfeatures->priv_version = SBI_HART_PRIV_VER_1_11;
 			hfeatures->features |= SBI_HART_HAS_MCOUNTINHIBIT;
+		}
+	}
+
+	/* Detect if hart has menvcfg CSR */
+	csr_read_allowed(CSR_MENVCFG, (unsigned long)&trap);
+	if (!trap.cause) {
+		hfeatures->priv_version = SBI_HART_PRIV_VER_1_12;
+		hfeatures->features |= SBI_HART_HAS_MENVCFG;
 	}
 
 	/* Counter overflow/filtering is not useful without mcounter/inhibit */
@@ -625,11 +670,6 @@ __mhpm_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;
-
 	/**
 	 * Detect if hart supports stimecmp CSR(Sstc extension) and menvcfg is
 	 * implemented.
diff --git a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c
index 2b9e5ae..660b11f 100644
--- a/lib/sbi/sbi_init.c
+++ b/lib/sbi/sbi_init.c
@@ -139,6 +139,8 @@ static void sbi_boot_print_hart(struct sbi_scratch *scratch, u32 hartid)
 	/* Boot HART details */
 	sbi_printf("Boot HART ID              : %u\n", hartid);
 	sbi_printf("Boot HART Domain          : %s\n", dom->name);
+	sbi_hart_get_priv_version_str(scratch, str, sizeof(str));
+	sbi_printf("Boot HART Priv Version    : %s\n", str);
 	misa_string(xlen, str, sizeof(str));
 	sbi_printf("Boot HART ISA             : %s\n", str);
 	sbi_hart_get_features_str(scratch, str, sizeof(str));