[PATCH v2 3/5] lib: sbi: Detect and print MHPM counters at boot-time

[Anup Patel]

A RISC-V platform can leave unimplemented MHPM counters hard-wired
to zero. We extend hart_detect_features() to detect MHPM counters
which are accessible and not hard-wired to zero. We also print
number of available MHPM counters as part of boot prints.

Signed-off-by: Anup Patel <anup.patel at wdc.com>
---
 include/sbi/sbi_hart.h |  1 +
 lib/sbi/sbi_hart.c     | 17 +++++++++++++++++
 lib/sbi/sbi_init.c     |  1 +
 3 files changed, 19 insertions(+)

diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
index c2ea686..1e1eb67 100644
--- a/include/sbi/sbi_hart.h
+++ b/include/sbi/sbi_hart.h
@@ -35,6 +35,7 @@ static inline ulong sbi_hart_expected_trap_addr(void)
 	return (ulong)sbi_hart_expected_trap;
 }
 
+unsigned int sbi_hart_mhpm_count(struct sbi_scratch *scratch);
 void sbi_hart_delegation_dump(struct sbi_scratch *scratch);
 unsigned int sbi_hart_pmp_count(struct sbi_scratch *scratch);
 int sbi_hart_pmp_get(struct sbi_scratch *scratch, unsigned int n,
diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
index 8f31d58..2211c3c 100644
--- a/lib/sbi/sbi_hart.c
+++ b/lib/sbi/sbi_hart.c
@@ -28,6 +28,7 @@ void (*sbi_hart_expected_trap)(void) = &__sbi_expected_trap;
 struct hart_features {
 	unsigned long features;
 	unsigned int pmp_count;
+	unsigned int mhpm_count;
 };
 static unsigned long hart_features_offset;
 
@@ -135,6 +136,14 @@ void sbi_hart_delegation_dump(struct sbi_scratch *scratch)
 #endif
 }
 
+unsigned int sbi_hart_mhpm_count(struct sbi_scratch *scratch)
+{
+	struct hart_features *hfeatures =
+			sbi_scratch_offset_ptr(scratch, hart_features_offset);
+
+	return hfeatures->mhpm_count;
+}
+
 unsigned int sbi_hart_pmp_count(struct sbi_scratch *scratch)
 {
 	struct hart_features *hfeatures =
@@ -339,6 +348,7 @@ static void hart_detect_features(struct sbi_scratch *scratch)
 	hfeatures = sbi_scratch_offset_ptr(scratch, hart_features_offset);
 	hfeatures->features = 0;
 	hfeatures->pmp_count = 0;
+	hfeatures->mhpm_count = 0;
 
 #define __check_csr(__csr, __rdonly, __wrval, __field, __skip)	\
 	val = csr_read_allowed(__csr, (ulong)&trap);			\
@@ -382,6 +392,13 @@ static void hart_detect_features(struct sbi_scratch *scratch)
 	__check_csr_64(CSR_PMPADDR0, 0, PMP_ADDR_MASK, pmp_count, __pmp_skip);
 __pmp_skip:
 
+	/* Detect number of MHPM counters */
+	__check_csr(CSR_MHPMCOUNTER3, 0, 1UL, mhpm_count, __mhpm_skip);
+	__check_csr_4(CSR_MHPMCOUNTER4, 0, 1UL, mhpm_count, __mhpm_skip);
+	__check_csr_8(CSR_MHPMCOUNTER8, 0, 1UL, mhpm_count, __mhpm_skip);
+	__check_csr_16(CSR_MHPMCOUNTER16, 0, 1UL, mhpm_count, __mhpm_skip);
+__mhpm_skip:
+
 #undef __check_csr_64
 #undef __check_csr_32
 #undef __check_csr_16
diff --git a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c
index c438eaa..e1a1d96 100644
--- a/lib/sbi/sbi_init.c
+++ b/lib/sbi/sbi_init.c
@@ -70,6 +70,7 @@ static void sbi_boot_prints(struct sbi_scratch *scratch, u32 hartid)
 	sbi_hart_get_features_str(scratch, str, sizeof(str));
 	sbi_printf("BOOT HART Features  : %s\n", str);
 	sbi_printf("BOOT HART PMP Count : %d\n", sbi_hart_pmp_count(scratch));
+	sbi_printf("BOOT HART MHPM Count: %d\n", sbi_hart_mhpm_count(scratch));
 
 	/* Firmware details */
 	sbi_printf("Firmware Base       : 0x%lx\n", scratch->fw_start);
-- 
2.25.1