From: Atish Patra <atish.patra@wdc.com>
Date: Sat, 10 Jul 2021 16:18:03 +0000 (-0700)
Subject: lib: sbi: Detect mcountinihibit support at runtime
X-Git-Tag: v1.0~114
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=fde28fadc2603c7c7a4afa7c2e7b96cc7b11d2e2;p=platform%2Fkernel%2Fopensbi.git

lib: sbi: Detect mcountinihibit support at runtime

RISC-V ISA specification v1.11 defined mcountinhibit CSR that allows
software to stop any counter from incrementing. The SBI PMU extension
depends on this CSR support in hardware.

Define mcountinhibit as a hart specific feature and detect it at runtime.

Reviewed-by: Anup Patel <anup.patel@wdc.com>
Signed-off-by: Atish Patra <atish.patra@wdc.com>
---

diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
index 031c7b0..9e317c5 100644
--- a/include/sbi/sbi_hart.h
+++ b/include/sbi/sbi_hart.h
@@ -18,8 +18,10 @@ enum sbi_hart_features {
 	SBI_HART_HAS_SCOUNTEREN = (1 << 0),
 	/** Hart has M-mode counter enable */
 	SBI_HART_HAS_MCOUNTEREN = (1 << 1),
+	/** Hart has counter inhibit CSR */
+	SBI_HART_HAS_MCOUNTINHIBIT = (1 << 2),
 	/** HART has timer csr implementation in hardware */
-	SBI_HART_HAS_TIME = (1 << 2),
+	SBI_HART_HAS_TIME = (1 << 3),
 
 	/** Last index of Hart features*/
 	SBI_HART_HAS_LAST_FEATURE = SBI_HART_HAS_TIME,
diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
index 56878b4..0bd1db1 100644
--- a/lib/sbi/sbi_hart.c
+++ b/lib/sbi/sbi_hart.c
@@ -259,6 +259,9 @@ static inline char *sbi_hart_feature_id2string(unsigned long feature)
 	case SBI_HART_HAS_MCOUNTEREN:
 		fstr = "mcounteren";
 		break;
+	case SBI_HART_HAS_MCOUNTINHIBIT:
+		fstr = "mcountinhibit";
+		break;
 	case SBI_HART_HAS_TIME:
 		fstr = "time";
 		break;
@@ -421,6 +424,14 @@ __mhpm_skip:
 			hfeatures->features |= SBI_HART_HAS_MCOUNTEREN;
 	}
 
+	/* Detect if hart supports MCOUNTINHIBIT feature */
+	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->features |= SBI_HART_HAS_MCOUNTINHIBIT;
+	}
+
 	/* Detect if hart supports time CSR */
 	csr_read_allowed(CSR_TIME, (unsigned long)&trap);
 	if (!trap.cause)