[v12,13/17] counter: Implement signalZ_action_component_id sysfs attribute

Commit Message

William Breathitt Gray July 5, 2021, 8:19 a.m. UTC

The Generic Counter chrdev interface expects users to supply component
IDs in order to select Synapses for requests. In order for users to know
what component ID belongs to which Synapse this information must be
exposed. The signalZ_action_component_id attribute provides a way for
users to discover what component ID belongs to the respective Synapse.

Cc: David Lechner <[e-mail]>
Cc: Gwendal Grignou <[e-mail]>
Cc: Dan Carpenter <[e-mail]>
Signed-off-by: William Breathitt Gray <[e-mail]>
---
 Documentation/ABI/testing/sysfs-bus-counter |  7 ++++
 drivers/counter/counter-sysfs.c             | 45 +++++++++++++++++++++
 2 files changed, 52 insertions(+)

Comments

David Lechner July 10, 2021, 4:20 p.m. UTC | #1

On 7/5/21 3:19 AM, William Breathitt Gray wrote:
> The Generic Counter chrdev interface expects users to supply component
> IDs in order to select Synapses for requests. In order for users to know
> what component ID belongs to which Synapse this information must be
> exposed. The signalZ_action_component_id attribute provides a way for
> users to discover what component ID belongs to the respective Synapse.
> 
> Cc: David Lechner <[e-mail]>
> Cc: Gwendal Grignou <[e-mail]>
> Cc: Dan Carpenter <[e-mail]>
> Signed-off-by: William Breathitt Gray <[e-mail]>
> ---

I like this better than having to scrape the number from the
attribute name.

Reviewed-by: David Lechner <[e-mail]>

> +	/* Allocate Counter attribute */
> +	counter_attr = devm_kzalloc(dev, sizeof(*counter_attr), GFP_KERNEL);

nit: Comments like this are redundant and can be omitted. All 3 words
in the comment are literally (abbreviated) in the next line of code so
it doesn't add any new/useful information.

Patch

diff --git a/Documentation/ABI/testing/sysfs-bus-counter b/Documentation/ABI/testing/sysfs-bus-counter
index dee79b606847..9809d8a47431 100644
--- a/Documentation/ABI/testing/sysfs-bus-counter
+++ b/Documentation/ABI/testing/sysfs-bus-counter
@@ -203,6 +203,13 @@  Description:
 		both edges:
 			Any state transition.
 
+What:		/sys/bus/counter/devices/counterX/countY/signalZ_action_component_id
+KernelVersion:	5.15
+Contact:	[e-mail]
+Description:
+		Read-only attribute that indicates the component ID of the
+		respective Synapse of Count Y for Signal Z.
+
 What:		/sys/bus/counter/devices/counterX/countY/spike_filter_ns
 KernelVersion:	5.14
 Contact:	[e-mail]
diff --git a/drivers/counter/counter-sysfs.c b/drivers/counter/counter-sysfs.c
index 07588130600a..bb49a10f160b 100644
--- a/drivers/counter/counter-sysfs.c
+++ b/drivers/counter/counter-sysfs.c
@@ -533,6 +533,46 @@  static int counter_name_attr_create(struct device *const dev,
 	return 0;
 }
 
+static ssize_t counter_comp_id_show(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	const size_t id = (size_t)to_counter_attribute(attr)->comp.priv;
+
+	return sprintf(buf, "%zu\n", id);
+}
+
+static int counter_comp_id_attr_create(struct device *const dev,
+				       struct counter_attribute_group *const group,
+				       const char *name, const size_t id)
+{
+	struct counter_attribute *counter_attr;
+
+	/* Allocate Counter attribute */
+	counter_attr = devm_kzalloc(dev, sizeof(*counter_attr), GFP_KERNEL);
+	if (!counter_attr)
+		return -ENOMEM;
+
+	/* Generate component ID name */
+	name = devm_kasprintf(dev, GFP_KERNEL, "%s_component_id", name);
+	if (!name)
+		return -ENOMEM;
+
+	/* Configure Counter attribute */
+	counter_attr->comp.priv = (void *)id;
+
+	/* Configure device attribute */
+	sysfs_attr_init(&counter_attr->dev_attr.attr);
+	counter_attr->dev_attr.attr.name = name;
+	counter_attr->dev_attr.attr.mode = 0444;
+	counter_attr->dev_attr.show = counter_comp_id_show;
+
+	/* Store list node */
+	list_add(&counter_attr->l, &group->attr_list);
+	group->num_attr++;
+
+	return 0;
+}
+
 static struct counter_comp counter_signal_comp = {
 	.type = COUNTER_COMP_SIGNAL_LEVEL,
 	.name = "signal",
@@ -627,6 +667,11 @@  static int counter_sysfs_synapses_add(struct counter_device *const counter,
 					  COUNTER_SCOPE_COUNT, count);
 		if (err < 0)
 			return err;
+
+		/* Create Synapse component ID attribute */
+		err = counter_comp_id_attr_create(dev, group, comp.name, i);
+		if (err < 0)
+			return err;
 	}
 
 	return 0;