[PATCH v3 2/4] platform/mellanox: mlxbf-pmc: Add support for 64-bit counters and cycle count

[Shravan Kumar Ramani]

Add support for programming any counter to monitor the cycle count.
This will allow the user to repurpose and dedicate any of the counters
in the block to counting cycles.
Since counting of cycles using 32-bit counters would result in frequent
wraparounds, add the ability to combine 2 adjacent 32-bit counters to
form 1 64-bit counter. The 64-bit value can be read via the same 2
counter sysfs  which will each hold the lower and upper 32 bits.
Both these features are supported by BlueField-3 PMC hardware, hence
the required bit-fields are exposed by the driver via sysfs to allow
the user to configure as needed.

Signed-off-by: Shravan Kumar Ramani <shravankr@xxxxxxxxxx>
Reviewed-by: David Thompson <davthompson@xxxxxxxxxx>
Reviewed-by: Vadim Pasternak <vadimp@xxxxxxxxxx>
---
 drivers/platform/mellanox/mlxbf-pmc.c | 134 ++++++++++++++++++++++++++
 1 file changed, 134 insertions(+)

diff --git a/drivers/platform/mellanox/mlxbf-pmc.c b/drivers/platform/mellanox/mlxbf-pmc.c
index 4ed9c7fd2b62..635ecc3b3845 100644
--- a/drivers/platform/mellanox/mlxbf-pmc.c
+++ b/drivers/platform/mellanox/mlxbf-pmc.c
@@ -88,6 +88,8 @@
 #define MLXBF_PMC_CRSPACE_PERFMON_CTL(n) (n * MLXBF_PMC_CRSPACE_PERFMON_REG0_SZ)
 #define MLXBF_PMC_CRSPACE_PERFMON_EN BIT(30)
 #define MLXBF_PMC_CRSPACE_PERFMON_CLR BIT(28)
+#define MLXBF_PMC_CRSPACE_PERFMON_UOC GENMASK(15, 0)
+#define MLXBF_PMC_CRSPACE_PERFMON_COUNT_CLOCK(n) (MLXBF_PMC_CRSPACE_PERFMON_CTL(n) + 0x4)
 #define MLXBF_PMC_CRSPACE_PERFMON_VAL0(n) (MLXBF_PMC_CRSPACE_PERFMON_CTL(n) + 0xc)
 
 /**
@@ -114,6 +116,8 @@ struct mlxbf_pmc_attribute {
  * @attr_event: Attributes for "event" sysfs files
  * @attr_event_list: Attributes for "event_list" sysfs files
  * @attr_enable: Attributes for "enable" sysfs files
+ * @attr_use_odd_counter: Attributes for "use_odd_counter" sysfs files
+ * @attr_count_clock: Attributes for "count_clock" sysfs files
  * @block_attr: All attributes needed for the block
  * @block_attr_grp: Attribute group for the block
  */
@@ -126,6 +130,8 @@ struct mlxbf_pmc_block_info {
 	struct mlxbf_pmc_attribute *attr_event;
 	struct mlxbf_pmc_attribute attr_event_list;
 	struct mlxbf_pmc_attribute attr_enable;
+	struct mlxbf_pmc_attribute attr_use_odd_counter;
+	struct mlxbf_pmc_attribute attr_count_clock;
 	struct attribute *block_attr[MLXBF_PMC_MAX_ATTRS];
 	struct attribute_group block_attr_grp;
 };
@@ -1763,6 +1769,103 @@ static ssize_t mlxbf_pmc_enable_store(struct device *dev,
 	return count;
 }
 
+/* Show function for "use_odd_counter" sysfs files - only for crspace */
+static ssize_t mlxbf_pmc_use_odd_counter_show(struct device *dev,
+					      struct device_attribute *attr, char *buf)
+{
+	struct mlxbf_pmc_attribute *attr_use_odd_counter = container_of(
+		attr, struct mlxbf_pmc_attribute, dev_attr);
+	unsigned int blk_num;
+	u32 value, reg;
+
+	blk_num = attr_use_odd_counter->nr;
+
+	if (mlxbf_pmc_readl(pmc->block[blk_num].mmio_base +
+			MLXBF_PMC_CRSPACE_PERFMON_CTL(pmc->block[blk_num].counters),
+			&reg))
+		return -EINVAL;
+
+	value = FIELD_GET(MLXBF_PMC_CRSPACE_PERFMON_UOC, reg);
+
+	return sysfs_emit(buf, "%u\n", value);
+}
+
+/* Store function for "use_odd_counter" sysfs files - only for crspace */
+static ssize_t mlxbf_pmc_use_odd_counter_store(struct device *dev,
+					       struct device_attribute *attr,
+					       const char *buf, size_t count)
+{
+	struct mlxbf_pmc_attribute *attr_use_odd_counter = container_of(
+		attr, struct mlxbf_pmc_attribute, dev_attr);
+	unsigned int blk_num;
+	u32 uoc, reg;
+	int err;
+
+	blk_num = attr_use_odd_counter->nr;
+
+	err = kstrtouint(buf, 0, &uoc);
+	if (err < 0)
+		return err;
+
+	err = mlxbf_pmc_readl(pmc->block[blk_num].mmio_base +
+		MLXBF_PMC_CRSPACE_PERFMON_CTL(pmc->block[blk_num].counters),
+		&reg);
+	if (err)
+		return -EINVAL;
+
+	reg &= ~MLXBF_PMC_CRSPACE_PERFMON_UOC;
+	reg |= FIELD_PREP(MLXBF_PMC_CRSPACE_PERFMON_UOC, uoc);
+
+	mlxbf_pmc_write(pmc->block[blk_num].mmio_base +
+		MLXBF_PMC_CRSPACE_PERFMON_CTL(pmc->block[blk_num].counters),
+		MLXBF_PMC_WRITE_REG_32, reg);
+
+	return count;
+}
+
+/* Show function for "count_clock" sysfs files - only for crspace */
+static ssize_t mlxbf_pmc_count_clock_show(struct device *dev,
+					  struct device_attribute *attr, char *buf)
+{
+	struct mlxbf_pmc_attribute *attr_count_clock = container_of(
+		attr, struct mlxbf_pmc_attribute, dev_attr);
+	unsigned int blk_num;
+	u32 reg;
+
+	blk_num = attr_count_clock->nr;
+
+	if (mlxbf_pmc_readl(pmc->block[blk_num].mmio_base +
+			MLXBF_PMC_CRSPACE_PERFMON_COUNT_CLOCK(pmc->block[blk_num].counters),
+			&reg))
+		return -EINVAL;
+
+	return sysfs_emit(buf, "%u\n", reg);
+}
+
+/* Store function for "count_clock" sysfs files - only for crspace */
+static ssize_t mlxbf_pmc_count_clock_store(struct device *dev,
+					   struct device_attribute *attr,
+					   const char *buf, size_t count)
+{
+	struct mlxbf_pmc_attribute *attr_count_clock = container_of(
+		attr, struct mlxbf_pmc_attribute, dev_attr);
+	unsigned int blk_num;
+	u32 reg;
+	int err;
+
+	blk_num = attr_count_clock->nr;
+
+	err = kstrtouint(buf, 0, &reg);
+	if (err < 0)
+		return err;
+
+	mlxbf_pmc_write(pmc->block[blk_num].mmio_base +
+		MLXBF_PMC_CRSPACE_PERFMON_COUNT_CLOCK(pmc->block[blk_num].counters),
+		MLXBF_PMC_WRITE_REG_32, reg);
+
+	return count;
+}
+
 /* Populate attributes for blocks with counters to monitor performance */
 static int mlxbf_pmc_init_perftype_counter(struct device *dev, unsigned int blk_num)
 {
@@ -1799,6 +1902,37 @@ static int mlxbf_pmc_init_perftype_counter(struct device *dev, unsigned int blk_
 		attr = NULL;
 	}
 
+	if (pmc->block[blk_num].type == MLXBF_PMC_TYPE_CRSPACE) {
+		/*
+		 * Couple adjacent odd and even 32-bit counters to form 64-bit counters
+		 * using "use_odd_counter" sysfs which has one bit per even counter.
+		 */
+		attr = &pmc->block[blk_num].attr_use_odd_counter;
+		attr->dev_attr.attr.mode = 0644;
+		attr->dev_attr.show = mlxbf_pmc_use_odd_counter_show;
+		attr->dev_attr.store = mlxbf_pmc_use_odd_counter_store;
+		attr->nr = blk_num;
+		attr->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
+							  "use_odd_counter");
+		if (!attr->dev_attr.attr.name)
+			return -ENOMEM;
+		pmc->block[blk_num].block_attr[++i] = &attr->dev_attr.attr;
+		attr = NULL;
+
+		/* Program crspace counters to count clock cycles using "count_clock" sysfs */
+		attr = &pmc->block[blk_num].attr_count_clock;
+		attr->dev_attr.attr.mode = 0644;
+		attr->dev_attr.show = mlxbf_pmc_count_clock_show;
+		attr->dev_attr.store = mlxbf_pmc_count_clock_store;
+		attr->nr = blk_num;
+		attr->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
+							  "count_clock");
+		if (!attr->dev_attr.attr.name)
+			return -ENOMEM;
+		pmc->block[blk_num].block_attr[++i] = &attr->dev_attr.attr;
+		attr = NULL;
+	}
+
 	pmc->block[blk_num].attr_counter = devm_kcalloc(
 		dev, pmc->block[blk_num].counters,
 		sizeof(struct mlxbf_pmc_attribute), GFP_KERNEL);
-- 
2.30.1