From 867c65360df283f056afa963ad8333e9c1eb21bb Mon Sep 17 00:00:00 2001
From: Atish Patra <atish.patra@wdc.com>
Date: Mon, 8 Nov 2021 10:52:58 -0800
Subject: lib: sbi: Detect Sscofpmf extension at run time
Sscofpmf ISA extension introduces PMU counter overflow and filtering support.
It introduces a read only `scountovf` csr that can be used to detect if
a hart supports this extension at runtime. However, this feature is only
useful if the hart already supports mcounteren and mcountinhibit.
Add a dynamic detection mechanism and boot time print message if sscofpmf
is present.
Reviewed-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
lib/sbi/sbi_hart.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
(limited to 'lib')
diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
index 8eb0c38..7f31bb7 100644
--- a/lib/sbi/sbi_hart.c
+++ b/lib/sbi/sbi_hart.c
@@ -281,6 +281,9 @@ static inline char *sbi_hart_feature_id2string(unsigned long feature)
case SBI_HART_HAS_MCOUNTINHIBIT:
fstr = "mcountinhibit";
break;
+ case SBI_HART_HAS_SSCOFPMF:
+ fstr = "sscofpmf";
+ break;
case SBI_HART_HAS_TIME:
fstr = "time";
break;
@@ -490,6 +493,15 @@ __mhpm_skip:
hfeatures->features |= SBI_HART_HAS_MCOUNTINHIBIT;
}
+ /* Counter overflow/filtering is not useful without mcounter/inhibit */
+ if (hfeatures->features & SBI_HART_HAS_MCOUNTINHIBIT &&
+ hfeatures->features & SBI_HART_HAS_MCOUNTEREN) {
+ /* Detect if hart supports sscofpmf */
+ csr_read_allowed(CSR_SCOUNTOVF, (unsigned long)&trap);
+ if (!trap.cause)
+ hfeatures->features |= SBI_HART_HAS_SSCOFPMF;
+ }
+
/* Detect if hart supports time CSR */
csr_read_allowed(CSR_TIME, (unsigned long)&trap);
if (!trap.cause)
--
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