[v2 1/2] lib: sbi_pmu: Add PMU snapshot definitions

[Atish Patra]

OpenSBI doesn't support SBI PMU snapshot yet as there is not much benefit
unless the multiple counters overflow at the same time.

Just add the definition and return not supported error at this moment. The
default returned error is also not supported. Thus, no functional change
intended.

Reviewed-by: Anup Patel <anup at brainfault.org>
Signed-off-by: Atish Patra <atishp at rivosinc.com>
---
 include/sbi/sbi_ecall_interface.h | 6 +++++-
 include/sbi/sbi_error.h           | 1 +
 lib/sbi/sbi_ecall_pmu.c           | 2 ++
 lib/sbi/sbi_pmu.c                 | 6 ++++++
 4 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/include/sbi/sbi_ecall_interface.h b/include/sbi/sbi_ecall_interface.h
index 1fe469e37078..d8c646d7b073 100644
--- a/include/sbi/sbi_ecall_interface.h
+++ b/include/sbi/sbi_ecall_interface.h
@@ -103,6 +103,7 @@
 #define SBI_EXT_PMU_COUNTER_STOP	0x4
 #define SBI_EXT_PMU_COUNTER_FW_READ	0x5
 #define SBI_EXT_PMU_COUNTER_FW_READ_HI	0x6
+#define SBI_EXT_PMU_SNAPSHOT_SET_SHMEM	0x7
 
 /** General pmu event codes specified in SBI PMU extension */
 enum sbi_pmu_hw_generic_events_t {
@@ -241,9 +242,11 @@ enum sbi_pmu_ctr_type {
 
 /* Flags defined for counter start function */
 #define SBI_PMU_START_FLAG_SET_INIT_VALUE (1 << 0)
+#define SBI_PMU_START_FLAG_INIT_FROM_SNAPSHOT (1 << 1)
 
 /* Flags defined for counter stop function */
 #define SBI_PMU_STOP_FLAG_RESET (1 << 0)
+#define SBI_PMU_STOP_FLAG_TAKE_SNAPSHOT (1 << 1)
 
 /* SBI function IDs for DBCN extension */
 #define SBI_EXT_DBCN_CONSOLE_WRITE		0x0
@@ -309,8 +312,9 @@ enum sbi_cppc_reg_id {
 #define SBI_ERR_ALREADY_AVAILABLE		-6
 #define SBI_ERR_ALREADY_STARTED			-7
 #define SBI_ERR_ALREADY_STOPPED			-8
+#define SBI_ERR_NO_SHMEM			-9
 
-#define SBI_LAST_ERR				SBI_ERR_ALREADY_STOPPED
+#define SBI_LAST_ERR				SBI_ERR_NO_SHMEM
 
 /* clang-format on */
 
diff --git a/include/sbi/sbi_error.h b/include/sbi/sbi_error.h
index dd65e14b6fcd..7f97506d8bd5 100644
--- a/include/sbi/sbi_error.h
+++ b/include/sbi/sbi_error.h
@@ -23,6 +23,7 @@
 #define SBI_EALREADY		SBI_ERR_ALREADY_AVAILABLE
 #define SBI_EALREADY_STARTED	SBI_ERR_ALREADY_STARTED
 #define SBI_EALREADY_STOPPED	SBI_ERR_ALREADY_STOPPED
+#define SBI_ENO_SHMEM		SBI_ERR_NO_SHMEM
 
 #define SBI_ENODEV		-1000
 #define SBI_ENOSYS		-1001
diff --git a/lib/sbi/sbi_ecall_pmu.c b/lib/sbi/sbi_ecall_pmu.c
index 1d5d512eeed7..c58591106d09 100644
--- a/lib/sbi/sbi_ecall_pmu.c
+++ b/lib/sbi/sbi_ecall_pmu.c
@@ -74,6 +74,8 @@ static int sbi_ecall_pmu_handler(unsigned long extid, unsigned long funcid,
 	case SBI_EXT_PMU_COUNTER_STOP:
 		ret = sbi_pmu_ctr_stop(regs->a0, regs->a1, regs->a2);
 		break;
+	case SBI_EXT_PMU_SNAPSHOT_SET_SHMEM:
+		/* fallthrough as OpenSBI doesn't support snapshot yet */
 	default:
 		ret = SBI_ENOTSUPP;
 	}
diff --git a/lib/sbi/sbi_pmu.c b/lib/sbi/sbi_pmu.c
index 185068bb1f43..1ac8562a9c99 100644
--- a/lib/sbi/sbi_pmu.c
+++ b/lib/sbi/sbi_pmu.c
@@ -442,6 +442,9 @@ int sbi_pmu_ctr_start(unsigned long cbase, unsigned long cmask,
 	if ((cbase + sbi_fls(cmask)) >= total_ctrs)
 		return ret;
 
+	if (flags & SBI_PMU_STOP_FLAG_TAKE_SNAPSHOT)
+		return SBI_ENO_SHMEM;
+
 	if (flags & SBI_PMU_START_FLAG_SET_INIT_VALUE)
 		bUpdate = true;
 
@@ -540,6 +543,9 @@ int sbi_pmu_ctr_stop(unsigned long cbase, unsigned long cmask,
 	if ((cbase + sbi_fls(cmask)) >= total_ctrs)
 		return SBI_EINVAL;
 
+	if (flag & SBI_PMU_STOP_FLAG_TAKE_SNAPSHOT)
+		return SBI_ENO_SHMEM;
+
 	for_each_set_bit(i, &cmask, BITS_PER_LONG) {
 		cidx = i + cbase;
 		event_idx_type = pmu_ctr_validate(phs, cidx, &event_code);
-- 
2.34.1