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

Cc: David Lechner <david@lechnology.com>
Cc: Gwendal Grignou <redacted>
Cc: Dan Carpenter <redacted>
Signed-off-by: William Breathitt Gray <redacted>
---
  Documentation/ABI/testing/sysfs-bus-counter | 16 ++++++++++-
  drivers/counter/counter-sysfs.c             | 30 ++++++++++++++++-----
  2 files changed, 39 insertions(+), 7 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-counter b/Documentation/ABI/testing/sysfs-bus-counter
index 9809d8a47431..e0e99adb0ecc 100644
--- a/Documentation/ABI/testing/sysfs-bus-counter
+++ b/Documentation/ABI/testing/sysfs-bus-counter

@@ -203,12 +203,26 @@ Description:
  		both edges:
  			Any state transition.
  
+What:		/sys/bus/counter/devices/counterX/countY/ceiling_component_id
+What:		/sys/bus/counter/devices/counterX/countY/floor_component_id
+What:		/sys/bus/counter/devices/counterX/countY/count_mode_component_id
+What:		/sys/bus/counter/devices/counterX/countY/direction_component_id
+What:		/sys/bus/counter/devices/counterX/countY/enable_component_id
+What:		/sys/bus/counter/devices/counterX/countY/error_noise_component_id
+What:		/sys/bus/counter/devices/counterX/countY/prescaler_component_id
+What:		/sys/bus/counter/devices/counterX/countY/preset_component_id
+What:		/sys/bus/counter/devices/counterX/countY/preset_enable_component_id
  What:		/sys/bus/counter/devices/counterX/countY/signalZ_action_component_id
+What:		/sys/bus/counter/devices/counterX/signalY/cable_fault_component_id
+What:		/sys/bus/counter/devices/counterX/signalY/cable_fault_enable_component_id
+What:		/sys/bus/counter/devices/counterX/signalY/filter_clock_prescaler_component_id
+What:		/sys/bus/counter/devices/counterX/signalY/index_polarity_component_id
+What:		/sys/bus/counter/devices/counterX/signalY/synchronous_mode_component_id

  KernelVersion:	5.15
  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.
+		respective extension or Synapse.
  
  What:		/sys/bus/counter/devices/counterX/countY/spike_filter_ns
  KernelVersion:	5.14

diff --git a/drivers/counter/counter-sysfs.c b/drivers/counter/counter-sysfs.c
index bb49a10f160b..eb1505bfbd89 100644
--- a/drivers/counter/counter-sysfs.c
+++ b/drivers/counter/counter-sysfs.c

@@ -587,6 +587,7 @@ static int counter_signal_attrs_create(struct counter_device *const counter,
  	int err;
  	struct counter_comp comp;
  	size_t i;
+	struct counter_comp *ext;
  
  	/* Create main Signal attribute */
  	comp = counter_signal_comp;

@@ -602,8 +603,13 @@ static int counter_signal_attrs_create(struct counter_device *const counter,
  
  	/* Create an attribute for each extension */
  	for (i = 0; i < signal->num_ext; i++) {
-		err = counter_attr_create(dev, group, signal->ext + i, scope,
-					  signal);
+		ext = signal->ext + i;
+
+		err = counter_attr_create(dev, group, ext, scope, signal);
+		if (err < 0)
+			return err;
+
+		err = counter_comp_id_attr_create(dev, group, ext->name, i);
  		if (err < 0)
  			return err;
  	}

@@ -694,6 +700,7 @@ static int counter_count_attrs_create(struct counter_device *const counter,
  	int err;
  	struct counter_comp comp;
  	size_t i;
+	struct counter_comp *ext;
  
  	/* Create main Count attribute */
  	comp = counter_count_comp;

@@ -718,8 +725,13 @@ static int counter_count_attrs_create(struct counter_device *const counter,
  
  	/* Create an attribute for each extension */
  	for (i = 0; i < count->num_ext; i++) {
-		err = counter_attr_create(dev, group, count->ext + i, scope,
-					  count);
+		ext = count->ext + i;

+
+		err = counter_attr_create(dev, group, ext, scope, count);
+		if (err < 0)
+			return err;
+
+		err = counter_comp_id_attr_create(dev, group, ext->name, i);
  		if (err < 0)
  			return err;
  	}

@@ -783,6 +795,7 @@ static int counter_sysfs_attr_add(struct counter_device *const counter,
  	struct device *const dev = &counter->dev;
  	int err;
  	size_t i;
+	struct counter_comp *ext;
  
  	/* Add Signals sysfs attributes */
  	err = counter_sysfs_signals_add(counter, group);

@@ -815,8 +828,13 @@ static int counter_sysfs_attr_add(struct counter_device *const counter,
  
  	/* Create an attribute for each extension */
  	for (i = 0; i < counter->num_ext; i++) {
-		err = counter_attr_create(dev, group, counter->ext + i, scope,
-					  NULL);
+		ext = counter->ext + i;