platform/mellanox: mlxbf-pmc: Fix reading of unprogrammed events

This fix involves 2 changes:
 - All event regs have a reset value of 0, which is not a valid
   event_number as per the event_list for most blocks and hence seen
   as an error. Add a "disable" event with event_number 0 for all blocks.

 - The enable bit for each counter need not be checked before
   reading the event info, and hence removed.

Fixes: 1a218d3 ("platform/mellanox: mlxbf-pmc: Add Mellanox BlueField PMC driver")
Signed-off-by: Shravan Kumar Ramani <shravankr@nvidia.com>
Reviewed-by: Vadim Pasternak <vadimp@nvidia.com>
Reviewed-by: David Thompson <davthompson@nvidia.com>
Link: https://lore.kernel.org/r/04d0213932d32681de1c716b54320ed894e52425.1693917738.git.shravankr@nvidia.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

drivers/platform/mellanox/mlxbf-pmc.c

@@ -191,6 +191,7 @@ static const struct mlxbf_pmc_events mlxbf_pmc_smgen_events[] = {
 };
 
 static const struct mlxbf_pmc_events mlxbf_pmc_trio_events_1[] = {
+	{ 0x0, "DISABLE" },
 	{ 0xa0, "TPIO_DATA_BEAT" },
 	{ 0xa1, "TDMA_DATA_BEAT" },
 	{ 0xa2, "MAP_DATA_BEAT" },
@@ -214,6 +215,7 @@ static const struct mlxbf_pmc_events mlxbf_pmc_trio_events_1[] = {
 };
 
 static const struct mlxbf_pmc_events mlxbf_pmc_trio_events_2[] = {
+	{ 0x0, "DISABLE" },
 	{ 0xa0, "TPIO_DATA_BEAT" },
 	{ 0xa1, "TDMA_DATA_BEAT" },
 	{ 0xa2, "MAP_DATA_BEAT" },
@@ -246,6 +248,7 @@ static const struct mlxbf_pmc_events mlxbf_pmc_trio_events_2[] = {
 };
 
 static const struct mlxbf_pmc_events mlxbf_pmc_ecc_events[] = {
+	{ 0x0, "DISABLE" },
 	{ 0x100, "ECC_SINGLE_ERROR_CNT" },
 	{ 0x104, "ECC_DOUBLE_ERROR_CNT" },
 	{ 0x114, "SERR_INJ" },
@@ -258,13 +261,15 @@ static const struct mlxbf_pmc_events mlxbf_pmc_ecc_events[] = {
 };
 
 static const struct mlxbf_pmc_events mlxbf_pmc_mss_events[] = {
+	{ 0x0, "DISABLE" },
 	{ 0xc0, "RXREQ_MSS" },
 	{ 0xc1, "RXDAT_MSS" },
 	{ 0xc2, "TXRSP_MSS" },
 	{ 0xc3, "TXDAT_MSS" },
 };
 
 static const struct mlxbf_pmc_events mlxbf_pmc_hnf_events[] = {
+	{ 0x0, "DISABLE" },
 	{ 0x45, "HNF_REQUESTS" },
 	{ 0x46, "HNF_REJECTS" },
 	{ 0x47, "ALL_BUSY" },
@@ -323,6 +328,7 @@ static const struct mlxbf_pmc_events mlxbf_pmc_hnf_events[] = {
 };
 
 static const struct mlxbf_pmc_events mlxbf_pmc_hnfnet_events[] = {
+	{ 0x0, "DISABLE" },
 	{ 0x12, "CDN_REQ" },
 	{ 0x13, "DDN_REQ" },
 	{ 0x14, "NDN_REQ" },
@@ -892,7 +898,7 @@ static int mlxbf_pmc_read_event(int blk_num, uint32_t cnt_num, bool is_l3,
 				uint64_t *result)
 {
 	uint32_t perfcfg_offset, perfval_offset;
-	uint64_t perfmon_cfg, perfevt, perfctl;
+	uint64_t perfmon_cfg, perfevt;
 
 	if (cnt_num >= pmc->block[blk_num].counters)
 		return -EINVAL;
@@ -904,25 +910,6 @@ static int mlxbf_pmc_read_event(int blk_num, uint32_t cnt_num, bool is_l3,
 	perfval_offset = perfcfg_offset +
 			 pmc->block[blk_num].counters * MLXBF_PMC_REG_SIZE;
 
-	/* Set counter in "read" mode */
-	perfmon_cfg = FIELD_PREP(MLXBF_PMC_PERFMON_CONFIG_ADDR,
-				 MLXBF_PMC_PERFCTL);
-	perfmon_cfg |= FIELD_PREP(MLXBF_PMC_PERFMON_CONFIG_STROBE, 1);
-	perfmon_cfg |= FIELD_PREP(MLXBF_PMC_PERFMON_CONFIG_WR_R_B, 0);
-
-	if (mlxbf_pmc_write(pmc->block[blk_num].mmio_base + perfcfg_offset,
-			    MLXBF_PMC_WRITE_REG_64, perfmon_cfg))
-		return -EFAULT;
-
-	/* Check if the counter is enabled */
-
-	if (mlxbf_pmc_read(pmc->block[blk_num].mmio_base + perfval_offset,
-			   MLXBF_PMC_READ_REG_64, &perfctl))
-		return -EFAULT;
-
-	if (!FIELD_GET(MLXBF_PMC_PERFCTL_EN0, perfctl))
-		return -EINVAL;
-
 	/* Set counter in "read" mode */
 	perfmon_cfg = FIELD_PREP(MLXBF_PMC_PERFMON_CONFIG_ADDR,
 				 MLXBF_PMC_PERFEVT);