diff mbox series

[v2,2/4] platform/mellanox: mlxbf-pmc: Add support for 64-bit counters and cycle count

Message ID ce077a0db5d4afdbcc63a635fece9793aaae055f.1716205838.git.shravankr@nvidia.com (mailing list archive)
State New
Headers show
Series Updates to mlxbf-pmc | expand

Commit Message

Shravan Kumar Ramani May 20, 2024, 11:56 a.m. UTC 
Add support for programming any counter to monitor the cycle count.
Since counting of cycles using 32-bit ocunters would result in frequent
wraparounds, add the ability to combine 2 adjacent 32-bit counters to
form 1 64-bit counter.
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@nvidia.com>
Reviewed-by: David Thompson <davthompson@nvidia.com>
Reviewed-by: Vadim Pasternak <vadimp@nvidia.com>
---
 drivers/platform/mellanox/mlxbf-pmc.c | 134 ++++++++++++++++++++++++++
 1 file changed, 134 insertions(+)

Comments

Ilpo Järvinen May 27, 2024, 11:39 a.m. UTC | #1 
On Mon, 20 May 2024, Shravan Kumar Ramani wrote:

> Add support for programming any counter to monitor the cycle count.
> Since counting of cycles using 32-bit ocunters would result in frequent

counters

> wraparounds, add the ability to combine 2 adjacent 32-bit counters to
> form 1 64-bit counter.
> 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.

I'm trying to understand what happens for the other counter, when the 
use_odd_counter is enabled? This change also doesn't add code that would 
make the other counter -EBUSY, should that be done?

For 64-bit counter, I suppose the userspace is expected to read the full 
counter from two sysfs files and combine the value (your documentation 
doesn't explain this)? That seems non-optimal, why cannot kernel just 
return the full combined 64-value directly in kernel?

Similarly, are these cycle counters occupying the same space as non-cycle 
counters (so both can/cannot be used that the same time)? I'm asking this 
because you're adding a parallel interface to read the value and if it's 
either-or, I don't understand why the value needs to be read from 
different file depending on the counter counting in cycles or not.
diff mbox series

Patch

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);