counter: Implement signalZ_action_component_id sysfs attribute

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: Gwendal Grignou <gwendal@chromium.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: David Lechner <david@lechnology.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/a6c81b2f1f5d0b8d59b1ebe4f0fed04914b07547.1632884256.git.vilhelm.gray@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/Documentation/ABI/testing/sysfs-bus-counter b/Documentation/ABI/testing/sysfs-bus-counter
index dee79b606847dc80316f93ab3e5a0d70170b4b19..aa2cd3c10d74e0a2d89d84b8b47b107908bbf47a 100644 (file)
--- 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: 5.16
+Contact:       linux-iio@vger.kernel.org
+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:       linux-iio@vger.kernel.org

diff --git a/drivers/counter/counter-sysfs.c b/drivers/counter/counter-sysfs.c
index 108cbd838eb92eb78f6998f6d5236c9d93d41a0f..ee7ff1cde45493e6c0482b7ee3f6ab315c60f051 100644 (file)
--- a/drivers/counter/counter-sysfs.c
+++ b/drivers/counter/counter-sysfs.c
@@ -532,6 +532,46 @@ 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",
@@ -626,6 +666,11 @@ 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;