[PATCH v2 0/4] Add support for Counter array components

[PATCH v2 0/4] Add support for Counter array components

[William Breathitt Gray]

Changes in v2:
 - Fixed Counter array component id allocation; was previously
   allocating duplicate ids to subsequent components
 - Introduced the Signal polarity component
 - Added Signal polarity component for 104-quad-8 driver
 - Converted COUNTER_COMP_ARRAY_U64 to COUNTER_COMP_ARRAY
 - Added support for Counter arrays of Signal polarity component type
 - Introduced DEFINE_COUNTER_ARRAY helper macro to define Counter arrays

The COUNTER_COMP_ARRAY Counter component type is introduced to enable
support for Counter array components. With Counter array components,
exposure for buffers on counter devices can be defined via new Counter
array component macros. This should simplify code for driver authors who
would otherwise need to define individual Counter components for each
array element.

Driver authors can handle reads/writes for an array component by
receiving an element index via the `idx` parameter and processing the
respective value via the `val` parameter.

For example, suppose a driver wants to expose a Count's read-only
capture buffer of four elements using a callback
`foobar_capture_read()`::

        DEFINE_COUNTER_ARRAY(foobar_capture_array, COUNTER_COMP_U64,
                             NULL, 4)
        COUNTER_COMP_COUNT_ARRAY_U64("capture", foobar_capture_read,
                                     NULL, foobar_capture_array)

Respective sysfs attributes for each array element would appear for the
respective Count:

* /sys/bus/counter/devices/counterX/countY/capture0
* /sys/bus/counter/devices/counterX/countY/capture1
* /sys/bus/counter/devices/counterX/countY/capture2
* /sys/bus/counter/devices/counterX/countY/capture3

If a user tries to read _capture2_ for example, `idx` will be `2` when
passed to the `foobar_capture_read()` callback, and thus the driver
knows which array element to handle.

In addition, this patchset introduces the Signal polarity component,
which represents the active level of a respective Signal. There are two
possible states: positive (rising edge) and negative (falling edge). The
104-quad-8 driver is updated to expose its index_polarity functionality
via this new polarity component.

A macro COUNTER_COMP_ARRAY_POLARITY() is provided for driver authors to
support Counter arrays of Signal polarity component type;
DEFINE_COUNTER_AVAILABLE may be used to define the polarity modes that
are passed to DEFINE_COUNTER_ARRAY.

William Breathitt Gray (4):
  counter: Introduce the Signal polarity component
  counter: 104-quad-8: Add Signal polarity component
  counter: Consolidate Counter extension sysfs attribute creation
  counter: Introduce the COUNTER_COMP_ARRAY component type

 Documentation/ABI/testing/sysfs-bus-counter |  13 +
 drivers/counter/104-quad-8.c                |  35 +++
 drivers/counter/counter-sysfs.c             | 298 ++++++++++++++++----
 include/linux/counter.h                     | 131 +++++++++
 include/uapi/linux/counter.h                |   6 +
 5 files changed, 434 insertions(+), 49 deletions(-)


base-commit: a12224997bec72d231a8dd642876e6364decdc45
-- 
2.37.3

[PATCH v2 1/4] counter: Introduce the Signal polarity component

[William Breathitt Gray]

The Signal polarity component represents the active level of a
respective Signal. There are two possible states: positive (rising edge)
and negative (falling edge); enum counter_signal_polarity represents
these states. A convenience macro COUNTER_COMP_POLARITY() is provided
for driver authors to declare a Signal polarity component.

Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
---
 Documentation/ABI/testing/sysfs-bus-counter | 13 +++++++++++++
 drivers/counter/counter-sysfs.c             | 11 +++++++++++
 include/linux/counter.h                     | 10 ++++++++++
 include/uapi/linux/counter.h                |  6 ++++++
 4 files changed, 40 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-counter b/Documentation/ABI/testing/sysfs-bus-counter
index 06c2b3e27e0b..a234022f9add 100644
--- a/Documentation/ABI/testing/sysfs-bus-counter
+++ b/Documentation/ABI/testing/sysfs-bus-counter
@@ -303,6 +303,19 @@ Description:
 		Discrete set of available values for the respective Signal Y
 		configuration are listed in this file.
 
+What:		/sys/bus/counter/devices/counterX/signalY/polarity
+KernelVersion:	6.1
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Active level of Signal Y. The following polarity values are
+		available:
+
+		positive:
+			Signal high state considered active level (rising edge).
+
+		negative:
+			Signal low state considered active level (falling edge).
+
 What:		/sys/bus/counter/devices/counterX/signalY/name
 KernelVersion:	5.2
 Contact:	linux-iio@vger.kernel.org
diff --git a/drivers/counter/counter-sysfs.c b/drivers/counter/counter-sysfs.c
index 04eac41dad33..92d3d4f549cb 100644
--- a/drivers/counter/counter-sysfs.c
+++ b/drivers/counter/counter-sysfs.c
@@ -91,6 +91,11 @@ static const char *const counter_count_mode_str[] = {
 	[COUNTER_COUNT_MODE_MODULO_N] = "modulo-n"
 };
 
+static const char *const counter_signal_polarity_str[] = {
+	[COUNTER_SIGNAL_POLARITY_POSITIVE] = "positive",
+	[COUNTER_SIGNAL_POLARITY_NEGATIVE] = "negative"
+};
+
 static ssize_t counter_comp_u8_show(struct device *dev,
 				    struct device_attribute *attr, char *buf)
 {
@@ -201,6 +206,8 @@ static ssize_t counter_comp_u32_show(struct device *dev,
 		return sysfs_emit(buf, "%s\n", counter_count_direction_str[data]);
 	case COUNTER_COMP_COUNT_MODE:
 		return sysfs_emit(buf, "%s\n", counter_count_mode_str[data]);
+	case COUNTER_COMP_SIGNAL_POLARITY:
+		return sysfs_emit(buf, "%s\n", counter_signal_polarity_str[data]);
 	default:
 		return sysfs_emit(buf, "%u\n", (unsigned int)data);
 	}
@@ -252,6 +259,10 @@ static ssize_t counter_comp_u32_store(struct device *dev,
 		err = counter_find_enum(&data, avail->enums, avail->num_items,
 					buf, counter_count_mode_str);
 		break;
+	case COUNTER_COMP_SIGNAL_POLARITY:
+		err = counter_find_enum(&data, avail->enums, avail->num_items,
+					buf, counter_signal_polarity_str);
+		break;
 	default:
 		err = kstrtou32(buf, 0, &data);
 		break;
diff --git a/include/linux/counter.h b/include/linux/counter.h
index 1fe17f5adb09..d508b260aaca 100644
--- a/include/linux/counter.h
+++ b/include/linux/counter.h
@@ -31,6 +31,7 @@ enum counter_comp_type {
 	COUNTER_COMP_ENUM,
 	COUNTER_COMP_COUNT_DIRECTION,
 	COUNTER_COMP_COUNT_MODE,
+	COUNTER_COMP_SIGNAL_POLARITY,
 };
 
 /**
@@ -483,4 +484,13 @@ struct counter_available {
 #define COUNTER_COMP_PRESET_ENABLE(_read, _write) \
 	COUNTER_COMP_COUNT_BOOL("preset_enable", _read, _write)
 
+#define COUNTER_COMP_POLARITY(_read, _write, _available) \
+{ \
+	.type = COUNTER_COMP_SIGNAL_POLARITY, \
+	.name = "polarity", \
+	.signal_u32_read = (_read), \
+	.signal_u32_write = (_write), \
+	.priv = &(_available), \
+}
+
 #endif /* _COUNTER_H_ */
diff --git a/include/uapi/linux/counter.h b/include/uapi/linux/counter.h
index 96c5ffd368ad..e9610e1944dc 100644
--- a/include/uapi/linux/counter.h
+++ b/include/uapi/linux/counter.h
@@ -153,4 +153,10 @@ enum counter_synapse_action {
 	COUNTER_SYNAPSE_ACTION_BOTH_EDGES,
 };
 
+/* Signal polarity values */
+enum counter_signal_polarity {
+	COUNTER_SIGNAL_POLARITY_POSITIVE,
+	COUNTER_SIGNAL_POLARITY_NEGATIVE,
+};
+
 #endif /* _UAPI_COUNTER_H_ */
-- 
2.37.3

[PATCH v2 2/4] counter: 104-quad-8: Add Signal polarity component

[William Breathitt Gray]

The 104-quad-8 driver provides support for Index signal polarity modes
via the "index_polarity" Signal component. This patch exposes the same
functionality through the more standard "polarity" Signal component.

Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
---
 drivers/counter/104-quad-8.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
index 1323edfbe40c..2a9d8259ed4b 100644
--- a/drivers/counter/104-quad-8.c
+++ b/drivers/counter/104-quad-8.c
@@ -549,6 +549,32 @@ static int quad8_index_polarity_set(struct counter_device *counter,
 	return 0;
 }
 
+static int quad8_polarity_read(struct counter_device *counter,
+			       struct counter_signal *signal,
+			       enum counter_signal_polarity *polarity)
+{
+	int err;
+	u32 index_polarity;
+
+	err = quad8_index_polarity_get(counter, signal, &index_polarity);
+	if (err)
+		return err;
+
+	*polarity = (index_polarity) ? COUNTER_SIGNAL_POLARITY_POSITIVE :
+		COUNTER_SIGNAL_POLARITY_NEGATIVE;
+
+	return 0;
+}
+
+static int quad8_polarity_write(struct counter_device *counter,
+				struct counter_signal *signal,
+				enum counter_signal_polarity polarity)
+{
+	const u32 pol = (polarity == COUNTER_SIGNAL_POLARITY_POSITIVE) ? 1 : 0;
+
+	return quad8_index_polarity_set(counter, signal, pol);
+}
+
 static const char *const quad8_synchronous_modes[] = {
 	"non-synchronous",
 	"synchronous"
@@ -977,6 +1003,13 @@ static struct counter_comp quad8_signal_ext[] = {
 			       quad8_signal_fck_prescaler_write)
 };
 
+static const enum counter_signal_polarity quad8_polarities[] = {
+	COUNTER_SIGNAL_POLARITY_POSITIVE,
+	COUNTER_SIGNAL_POLARITY_NEGATIVE,
+};
+
+static DEFINE_COUNTER_AVAILABLE(quad8_polarity_available, quad8_polarities);
+
 static DEFINE_COUNTER_ENUM(quad8_index_pol_enum, quad8_index_polarity_modes);
 static DEFINE_COUNTER_ENUM(quad8_synch_mode_enum, quad8_synchronous_modes);
 
@@ -984,6 +1017,8 @@ static struct counter_comp quad8_index_ext[] = {
 	COUNTER_COMP_SIGNAL_ENUM("index_polarity", quad8_index_polarity_get,
 				 quad8_index_polarity_set,
 				 quad8_index_pol_enum),
+	COUNTER_COMP_POLARITY(quad8_polarity_read, quad8_polarity_write,
+			      quad8_polarity_available),
 	COUNTER_COMP_SIGNAL_ENUM("synchronous_mode", quad8_synchronous_mode_get,
 				 quad8_synchronous_mode_set,
 				 quad8_synch_mode_enum),
-- 
2.37.3

[PATCH v2 3/4] counter: Consolidate Counter extension sysfs attribute creation

[William Breathitt Gray]

Counter extensions are handled for the Device, Counts, and Signals. The
code loops through each Counter extension and creates the expected sysfs
attributes. This patch consolidates that code into functions to reduce
redundancy and make the intention of the code clearer.

Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
---
 drivers/counter/counter-sysfs.c | 98 ++++++++++++++++-----------------
 1 file changed, 49 insertions(+), 49 deletions(-)

diff --git a/drivers/counter/counter-sysfs.c b/drivers/counter/counter-sysfs.c
index 92d3d4f549cb..7ce7c51395da 100644
--- a/drivers/counter/counter-sysfs.c
+++ b/drivers/counter/counter-sysfs.c
@@ -591,6 +591,46 @@ static int counter_comp_id_attr_create(struct device *const dev,
 	return 0;
 }
 
+static int counter_ext_attrs_create(struct device *const dev,
+				    struct counter_attribute_group *const group,
+				    const struct counter_comp *const ext,
+				    const enum counter_scope scope,
+				    void *const parent, const size_t id)
+{
+	int err;
+
+	/* Create main extension attribute */
+	err = counter_attr_create(dev, group, ext, scope, parent);
+	if (err < 0)
+		return err;
+
+	/* Create extension id attribute */
+	return counter_comp_id_attr_create(dev, group, ext->name, id);
+}
+
+static int counter_sysfs_exts_add(struct device *const dev,
+				  struct counter_attribute_group *const group,
+				  const struct counter_comp *const exts,
+				  const size_t num_ext,
+				  const enum counter_scope scope,
+				  void *const parent)
+{
+	size_t i;
+	const struct counter_comp *ext;
+	int err;
+
+	/* Create attributes for each extension */
+	for (i = 0; i < num_ext; i++) {
+		ext = &exts[i];
+		err = counter_ext_attrs_create(dev, group, ext, scope, parent,
+					       i);
+		if (err < 0)
+			return err;
+	}
+
+	return 0;
+}
+
 static struct counter_comp counter_signal_comp = {
 	.type = COUNTER_COMP_SIGNAL_LEVEL,
 	.name = "signal",
@@ -604,8 +644,6 @@ static int counter_signal_attrs_create(struct counter_device *const counter,
 	struct device *const dev = &counter->dev;
 	int err;
 	struct counter_comp comp;
-	size_t i;
-	struct counter_comp *ext;
 
 	/* Create main Signal attribute */
 	comp = counter_signal_comp;
@@ -619,21 +657,9 @@ static int counter_signal_attrs_create(struct counter_device *const counter,
 	if (err < 0)
 		return err;
 
-	/* Create an attribute for each extension */
-	for (i = 0; i < signal->num_ext; i++) {
-		ext = &signal->ext[i];
-
-		err = counter_attr_create(dev, cattr_group, ext, scope, signal);
-		if (err < 0)
-			return err;
-
-		err = counter_comp_id_attr_create(dev, cattr_group, ext->name,
-						  i);
-		if (err < 0)
-			return err;
-	}
-
-	return 0;
+	/* Add Signal extensions */
+	return counter_sysfs_exts_add(dev, cattr_group, signal->ext,
+				      signal->num_ext, scope, signal);
 }
 
 static int counter_sysfs_signals_add(struct counter_device *const counter,
@@ -718,8 +744,6 @@ static int counter_count_attrs_create(struct counter_device *const counter,
 	struct device *const dev = &counter->dev;
 	int err;
 	struct counter_comp comp;
-	size_t i;
-	struct counter_comp *ext;
 
 	/* Create main Count attribute */
 	comp = counter_count_comp;
@@ -742,21 +766,9 @@ static int counter_count_attrs_create(struct counter_device *const counter,
 	if (err < 0)
 		return err;
 
-	/* Create an attribute for each extension */
-	for (i = 0; i < count->num_ext; i++) {
-		ext = &count->ext[i];
-
-		err = counter_attr_create(dev, cattr_group, ext, scope, count);
-		if (err < 0)
-			return err;
-
-		err = counter_comp_id_attr_create(dev, cattr_group, ext->name,
-						  i);
-		if (err < 0)
-			return err;
-	}
-
-	return 0;
+	/* Add Count extensions */
+	return counter_sysfs_exts_add(dev, cattr_group, count->ext,
+				      count->num_ext, scope, count);
 }
 
 static int counter_sysfs_counts_add(struct counter_device *const counter,
@@ -849,8 +861,6 @@ static int counter_sysfs_attr_add(struct counter_device *const counter,
 	const enum counter_scope scope = COUNTER_SCOPE_DEVICE;
 	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, cattr_group);
@@ -887,19 +897,9 @@ static int counter_sysfs_attr_add(struct counter_device *const counter,
 	if (err < 0)
 		return err;
 
-	/* Create an attribute for each extension */
-	for (i = 0; i < counter->num_ext; i++) {
-		ext = &counter->ext[i];
-
-		err = counter_attr_create(dev, cattr_group, ext, scope, NULL);
-		if (err < 0)
-			return err;
-
-		err = counter_comp_id_attr_create(dev, cattr_group, ext->name,
-						  i);
-		if (err < 0)
-			return err;
-	}
+	/* Add device extensions */
+	return counter_sysfs_exts_add(dev, cattr_group, counter->ext,
+				      counter->num_ext, scope, NULL);
 
 	return 0;
 }
-- 
2.37.3

[PATCH v2 4/4] counter: Introduce the COUNTER_COMP_ARRAY component type

[William Breathitt Gray]

The COUNTER_COMP_ARRAY Counter component type is introduced to enable
support for Counter array components. With Counter array components,
exposure for buffers on counter devices can be defined via new Counter
array component macros. This should simplify code for driver authors who
would otherwise need to define individual Counter components for each
array element.

Five Counter array component macros are introduced::

        DEFINE_COUNTER_ARRAY(_name, _type, _available, _length)
        COUNTER_COMP_DEVICE_ARRAY_U64(_name, _read, _write, _array)
        COUNTER_COMP_COUNT_ARRAY_U64(_name, _read, _write, _array)
        COUNTER_COMP_SIGNAL_ARRAY_U64(_name, _read, _write, _array)
        COUNTER_COMP_ARRAY_POLARITY(_read, _write, _array)

Eight Counter array callbacks are introduced as well::

        int (*signal_array_u32_read)(struct counter_device *counter,
                                     struct counter_signal *signal,
                                     size_t idx, u32 *val);
        int (*signal_array_u32_write)(struct counter_device *counter,
                                      struct counter_signal *signal,
                                      size_t idx, u32 val);
        int (*device_array_u64_read)(struct counter_device *counter,
                                     size_t idx, u64 *val);
        int (*count_array_u64_read)(struct counter_device *counter,
                                    struct counter_count *count,
                                    size_t idx, u64 *val);
        int (*signal_array_u64_read)(struct counter_device *counter,
                                     struct counter_signal *signal,
                                     size_t idx, u64 *val);
        int (*device_array_u64_write)(struct counter_device *counter,
                                      size_t idx, u64 val);
        int (*count_array_u64_write)(struct counter_device *counter,
                                     struct counter_count *count,
                                     size_t idx, u64 val);
        int (*signal_array_u64_write)(struct counter_device *counter,
                                      struct counter_signal *signal,
                                      size_t idx, u64 val);

Driver authors can handle reads/writes for an array component by
receiving an element index via the `idx` parameter and processing the
respective value via the `val` parameter.

For example, suppose a driver wants to expose a Count's read-only
capture buffer of four elements using a callback
`foobar_capture_read()`::

        DEFINE_COUNTER_ARRAY(foobar_capture_array, COUNTER_COMP_U64,
                             NULL, 4)
        COUNTER_COMP_COUNT_ARRAY_U64("capture", foobar_capture_read,
                                     NULL, foobar_capture_array)

Respective sysfs attributes for each array element would appear for the
respective Count:

* /sys/bus/counter/devices/counterX/countY/capture0
* /sys/bus/counter/devices/counterX/countY/capture1
* /sys/bus/counter/devices/counterX/countY/capture2
* /sys/bus/counter/devices/counterX/countY/capture3

If a user tries to read _capture2_ for example, `idx` will be `2` when
passed to the `foobar_capture_read()` callback, and thus the driver
knows which array element to handle.

Cc: Julien Panis <jpanis@baylibre.com>
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
---
 drivers/counter/counter-sysfs.c | 193 +++++++++++++++++++++++++++++++-
 include/linux/counter.h         | 121 ++++++++++++++++++++
 2 files changed, 312 insertions(+), 2 deletions(-)

diff --git a/drivers/counter/counter-sysfs.c b/drivers/counter/counter-sysfs.c
index 7ce7c51395da..ea4401b4d578 100644
--- a/drivers/counter/counter-sysfs.c
+++ b/drivers/counter/counter-sysfs.c
@@ -352,6 +352,124 @@ static ssize_t counter_comp_u64_store(struct device *dev,
 	return len;
 }
 
+static ssize_t counter_comp_array_u32_show(struct device *dev,
+					   struct device_attribute *attr,
+					   char *buf)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	struct counter_device *const counter = counter_from_dev(dev);
+	const struct counter_array *const element = a->comp.priv;
+	int err;
+	u32 data = 0;
+
+	if (a->scope != COUNTER_SCOPE_SIGNAL ||
+	    element->type != COUNTER_COMP_SIGNAL_POLARITY)
+		return -EINVAL;
+
+	err = a->comp.signal_array_u32_read(counter, a->parent, element->idx,
+					    &data);
+	if (err < 0)
+		return err;
+
+	return sysfs_emit(buf, "%s\n", counter_signal_polarity_str[data]);
+}
+
+static ssize_t counter_comp_array_u32_store(struct device *dev,
+					    struct device_attribute *attr,
+					    const char *buf, size_t len)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	struct counter_device *const counter = counter_from_dev(dev);
+	const struct counter_array *const element = a->comp.priv;
+	int err;
+	u32 data = 0;
+
+	if (element->type != COUNTER_COMP_SIGNAL_POLARITY ||
+	    a->scope != COUNTER_SCOPE_SIGNAL)
+		return -EINVAL;
+
+	err = counter_find_enum(&data, element->avail->enums,
+				element->avail->num_items, buf,
+				counter_signal_polarity_str);
+	if (err < 0)
+		return err;
+
+	err = a->comp.signal_array_u32_write(counter, a->parent, element->idx,
+					     data);
+	if (err < 0)
+		return err;
+
+	return len;
+}
+
+static ssize_t counter_comp_array_u64_show(struct device *dev,
+					   struct device_attribute *attr,
+					   char *buf)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	struct counter_device *const counter = counter_from_dev(dev);
+	const struct counter_array *const element = a->comp.priv;
+	int err;
+	u64 data = 0;
+
+	switch (a->scope) {
+	case COUNTER_SCOPE_DEVICE:
+		err = a->comp.device_array_u64_read(counter, element->idx,
+						    &data);
+		break;
+	case COUNTER_SCOPE_SIGNAL:
+		err = a->comp.signal_array_u64_read(counter, a->parent,
+						    element->idx, &data);
+		break;
+	case COUNTER_SCOPE_COUNT:
+		err = a->comp.count_array_u64_read(counter, a->parent,
+						   element->idx, &data);
+		break;
+	default:
+		return -EINVAL;
+	}
+	if (err < 0)
+		return err;
+
+	return sysfs_emit(buf, "%llu\n", (unsigned long long)data);
+}
+
+static ssize_t counter_comp_array_u64_store(struct device *dev,
+					    struct device_attribute *attr,
+					    const char *buf, size_t len)
+{
+	const struct counter_attribute *const a = to_counter_attribute(attr);
+	struct counter_device *const counter = counter_from_dev(dev);
+	const struct counter_array *const element = a->comp.priv;
+	int err;
+	u64 data = 0;
+
+	err = kstrtou64(buf, 0, &data);
+	if (err < 0)
+		return err;
+
+	switch (a->scope) {
+	case COUNTER_SCOPE_DEVICE:
+		err = a->comp.device_array_u64_write(counter, element->idx,
+						     data);
+		break;
+	case COUNTER_SCOPE_SIGNAL:
+		err = a->comp.signal_array_u64_write(counter, a->parent,
+						     element->idx, data);
+		break;
+	case COUNTER_SCOPE_COUNT:
+		err = a->comp.count_array_u64_write(counter, a->parent,
+						    element->idx, data);
+		break;
+	default:
+		return -EINVAL;
+	}
+	if (err < 0)
+		return err;
+
+	return len;
+}
+
 static ssize_t enums_available_show(const u32 *const enums,
 				    const size_t num_enums,
 				    const char *const strs[], char *buf)
@@ -446,6 +564,7 @@ static int counter_attr_create(struct device *const dev,
 			       const enum counter_scope scope,
 			       void *const parent)
 {
+	const struct counter_array *const array = comp->priv;
 	struct counter_attribute *counter_attr;
 	struct device_attribute *dev_attr;
 
@@ -499,6 +618,32 @@ static int counter_attr_create(struct device *const dev,
 			dev_attr->store = counter_comp_u64_store;
 		}
 		break;
+	case COUNTER_COMP_ARRAY:
+		switch (array->type) {
+		case COUNTER_COMP_SIGNAL_POLARITY:
+			if (comp->signal_array_u32_read) {
+				dev_attr->attr.mode |= 0444;
+				dev_attr->show = counter_comp_array_u32_show;
+			}
+			if (comp->signal_array_u32_write) {
+				dev_attr->attr.mode |= 0200;
+				dev_attr->store = counter_comp_array_u32_store;
+			}
+			break;
+		case COUNTER_COMP_U64:
+			if (comp->device_array_u64_read) {
+				dev_attr->attr.mode |= 0444;
+				dev_attr->show = counter_comp_array_u64_show;
+			}
+			if (comp->device_array_u64_write) {
+				dev_attr->attr.mode |= 0200;
+				dev_attr->store = counter_comp_array_u64_store;
+			}
+			break;
+		default:
+			return -EINVAL;
+		}
+		break;
 	default:
 		return -EINVAL;
 	}
@@ -608,6 +753,40 @@ static int counter_ext_attrs_create(struct device *const dev,
 	return counter_comp_id_attr_create(dev, group, ext->name, id);
 }
 
+static int counter_array_attrs_create(struct device *const dev,
+				      struct counter_attribute_group *const group,
+				      const struct counter_comp *const comp,
+				      const enum counter_scope scope,
+				      void *const parent, const size_t id)
+{
+	const struct counter_array *const array = comp->priv;
+	struct counter_comp ext = *comp;
+	struct counter_array *element;
+	size_t idx;
+	int err;
+
+	/* Create an attribute for each array element */
+	for (idx = 0; idx < array->length; idx++) {
+		/* Set index for array element extension */
+		element = ext.priv;
+		element->idx = idx;
+
+		/* Generate array element attribute name */
+		ext.name = devm_kasprintf(dev, GFP_KERNEL, "%s%zu", comp->name,
+					  idx);
+		if (!ext.name)
+			return -ENOMEM;
+
+		/* Create all attributes associated with the array element */
+		err = counter_ext_attrs_create(dev, group, &ext, scope, parent,
+					       id + idx);
+		if (err < 0)
+			return err;
+	}
+
+	return 0;
+}
+
 static int counter_sysfs_exts_add(struct device *const dev,
 				  struct counter_attribute_group *const group,
 				  const struct counter_comp *const exts,
@@ -618,12 +797,22 @@ static int counter_sysfs_exts_add(struct device *const dev,
 	size_t i;
 	const struct counter_comp *ext;
 	int err;
+	size_t id = 0;
+	const struct counter_array *array;
 
 	/* Create attributes for each extension */
 	for (i = 0; i < num_ext; i++) {
 		ext = &exts[i];
-		err = counter_ext_attrs_create(dev, group, ext, scope, parent,
-					       i);
+		if (ext->type == COUNTER_COMP_ARRAY) {
+			err = counter_array_attrs_create(dev, group, ext, scope,
+							 parent, id);
+			array = ext->priv;
+			id += array->length;
+		} else {
+			err = counter_ext_attrs_create(dev, group, ext, scope,
+						       parent, id);
+			id++;
+		}
 		if (err < 0)
 			return err;
 	}
diff --git a/include/linux/counter.h b/include/linux/counter.h
index d508b260aaca..61fe38e30626 100644
--- a/include/linux/counter.h
+++ b/include/linux/counter.h
@@ -32,6 +32,7 @@ enum counter_comp_type {
 	COUNTER_COMP_COUNT_DIRECTION,
 	COUNTER_COMP_COUNT_MODE,
 	COUNTER_COMP_SIGNAL_POLARITY,
+	COUNTER_COMP_ARRAY,
 };
 
 /**
@@ -69,6 +70,30 @@ enum counter_comp_type {
  * @signal_u64_read:		Signal u64 component read callback. The read value of
  *			the respective Signal u64 component should be passed
  *			back via the val parameter.
+ * @signal_array_u32_read:	Signal u32 array component read callback. The
+ *				index of the respective Count u32 array
+ *				component element is passed via the idx
+ *				parameter. The read value of the respective
+ *				Count u32 array component element should be
+ *				passed back via the val parameter.
+ * @device_array_u64_read:	Device u64 array component read callback. The
+ *				index of the respective Device u64 array
+ *				component element is passed via the idx
+ *				parameter. The read value of the respective
+ *				Device u64 array component element should be
+ *				passed back via the val parameter.
+ * @count_array_u64_read:	Count u64 array component read callback. The
+ *				index of the respective Count u64 array
+ *				component element is passed via the idx
+ *				parameter. The read value of the respective
+ *				Count u64 array component element should be
+ *				passed back via the val parameter.
+ * @signal_array_u64_read:	Signal u64 array component read callback. The
+ *				index of the respective Count u64 array
+ *				component element is passed via the idx
+ *				parameter. The read value of the respective
+ *				Count u64 array component element should be
+ *				passed back via the val parameter.
  * @action_write:		Synapse action mode write callback. The write value of
  *			the respective Synapse action mode is passed via the
  *			action parameter.
@@ -99,6 +124,30 @@ enum counter_comp_type {
  * @signal_u64_write:		Signal u64 component write callback. The write value of
  *			the respective Signal u64 component is passed via the
  *			val parameter.
+ * @signal_array_u32_write:	Signal u32 array component write callback. The
+ *				index of the respective Signal u32 array
+ *				component element is passed via the idx
+ *				parameter. The write value of the respective
+ *				Signal u32 array component element is passed via
+ *				the val parameter.
+ * @device_array_u64_write:	Device u64 array component write callback. The
+ *				index of the respective Device u64 array
+ *				component element is passed via the idx
+ *				parameter. The write value of the respective
+ *				Device u64 array component element is passed via
+ *				the val parameter.
+ * @count_array_u64_write:	Count u64 array component write callback. The
+ *				index of the respective Count u64 array
+ *				component element is passed via the idx
+ *				parameter. The write value of the respective
+ *				Count u64 array component element is passed via
+ *				the val parameter.
+ * @signal_array_u64_write:	Signal u64 array component write callback. The
+ *				index of the respective Signal u64 array
+ *				component element is passed via the idx
+ *				parameter. The write value of the respective
+ *				Signal u64 array component element is passed via
+ *				the val parameter.
  */
 struct counter_comp {
 	enum counter_comp_type type;
@@ -126,6 +175,17 @@ struct counter_comp {
 				      struct counter_count *count, u64 *val);
 		int (*signal_u64_read)(struct counter_device *counter,
 				       struct counter_signal *signal, u64 *val);
+		int (*signal_array_u32_read)(struct counter_device *counter,
+					     struct counter_signal *signal,
+					     size_t idx, u32 *val);
+		int (*device_array_u64_read)(struct counter_device *counter,
+					     size_t idx, u64 *val);
+		int (*count_array_u64_read)(struct counter_device *counter,
+					    struct counter_count *count,
+					    size_t idx, u64 *val);
+		int (*signal_array_u64_read)(struct counter_device *counter,
+					     struct counter_signal *signal,
+					     size_t idx, u64 *val);
 	};
 	union {
 		int (*action_write)(struct counter_device *counter,
@@ -149,6 +209,17 @@ struct counter_comp {
 				       struct counter_count *count, u64 val);
 		int (*signal_u64_write)(struct counter_device *counter,
 					struct counter_signal *signal, u64 val);
+		int (*signal_array_u32_write)(struct counter_device *counter,
+					      struct counter_signal *signal,
+					      size_t idx, u32 val);
+		int (*device_array_u64_write)(struct counter_device *counter,
+					      size_t idx, u64 val);
+		int (*count_array_u64_write)(struct counter_device *counter,
+					     struct counter_count *count,
+					     size_t idx, u64 val);
+		int (*signal_array_u64_write)(struct counter_device *counter,
+					      struct counter_signal *signal,
+					      size_t idx, u64 val);
 	};
 };
 
@@ -453,6 +524,47 @@ struct counter_available {
 	.priv = &(_available), \
 }
 
+struct counter_array {
+	enum counter_comp_type type;
+	const struct counter_available *avail;
+	union {
+		size_t length;
+		size_t idx;
+	};
+};
+
+#define DEFINE_COUNTER_ARRAY(_name, _type, _available, _length) \
+	struct counter_array _name = { \
+		.type = (_type), \
+		.avail = &(_available), \
+		.length = (_length), \
+	}
+
+#define COUNTER_COMP_DEVICE_ARRAY_U64(_name, _read, _write, _array) \
+{ \
+	.type = COUNTER_COMP_ARRAY, \
+	.name = (_name), \
+	.device_array_u64_read = (_read), \
+	.device_array_u64_write = (_write), \
+	.priv = &(_array), \
+}
+#define COUNTER_COMP_COUNT_ARRAY_U64(_name, _read, _write, _array) \
+{ \
+	.type = COUNTER_COMP_ARRAY, \
+	.name = (_name), \
+	.count_array_u64_read = (_read), \
+	.count_array_u64_write = (_write), \
+	.priv = &(_array), \
+}
+#define COUNTER_COMP_SIGNAL_ARRAY_U64(_name, _read, _write, _array) \
+{ \
+	.type = COUNTER_COMP_ARRAY, \
+	.name = (_name), \
+	.signal_array_u64_read = (_read), \
+	.signal_array_u64_write = (_write), \
+	.priv = &(_array), \
+}
+
 #define COUNTER_COMP_CEILING(_read, _write) \
 	COUNTER_COMP_COUNT_U64("ceiling", _read, _write)
 
@@ -493,4 +605,13 @@ struct counter_available {
 	.priv = &(_available), \
 }
 
+#define COUNTER_COMP_ARRAY_POLARITY(_read, _write, _array) \
+{ \
+	.type = COUNTER_COMP_ARRAY, \
+	.name = "polarity", \
+	.signal_array_u32_read = (_read), \
+	.signal_array_u32_write = (_write), \
+	.priv = &(_array), \
+}
+
 #endif /* _COUNTER_H_ */
-- 
2.37.3

Re: [PATCH v2 4/4] counter: Introduce the COUNTER_COMP_ARRAY component type

[William Breathitt Gray]

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On Fri, Sep 16, 2022 at 08:39:28PM -0400, William Breathitt Gray wrote:
> +static int counter_array_attrs_create(struct device *const dev,
> +				      struct counter_attribute_group *const group,
> +				      const struct counter_comp *const comp,
> +				      const enum counter_scope scope,
> +				      void *const parent, const size_t id)
> +{
> +	const struct counter_array *const array = comp->priv;
> +	struct counter_comp ext = *comp;
> +	struct counter_array *element;
> +	size_t idx;
> +	int err;
> +
> +	/* Create an attribute for each array element */
> +	for (idx = 0; idx < array->length; idx++) {
> +		/* Set index for array element extension */
> +		element = ext.priv;
> +		element->idx = idx;

This is unintentionally overwriting the array length and thus skipping
the subsequent array elements. Instead, element should be a copy of the
array rather than a pointer to it. I'll fix this in a v3 release.

William Breathitt Gray

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