counter: Introduce the COUNTER_COMP_ARRAY component type

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.

Eight Counter array component macros are introduced::

        DEFINE_COUNTER_ARRAY_U64(_name, _length)
        DEFINE_COUNTER_ARRAY_CAPTURE(_name, _length)
        DEFINE_COUNTER_ARRAY_POLARITY(_name, _enums, _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_CAPTURE(_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_CAPTURE(foobar_capture_array, 4);
        COUNTER_COMP_ARRAY_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.

Counter arrays for polarity elements can be defined in a similar
manner as u64 elements::

        const enum counter_signal_polarity foobar_polarity_states[] = {
                COUNTER_SIGNAL_POLARITY_POSITIVE,
                COUNTER_SIGNAL_POLARITY_NEGATIVE,
        };
        DEFINE_COUNTER_ARRAY_POLARITY(foobar_polarity_array,
                                      foobar_polarity_states, 4);
        COUNTER_COMP_ARRAY_POLARITY(foobar_polarity_read,
                                    foobar_polarity_write,
                                    foobar_polarity_array)

Tested-by: Julien Panis <jpanis@baylibre.com>
Link: https://lore.kernel.org/r/5310c22520aeae65b1b74952419f49ac4c8e1ec1.1664204990.git.william.gray@linaro.org/
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
Link: https://lore.kernel.org/r/a51fd608704bdfc5a0efa503fc5481df34241e0a.1664318353.git.william.gray@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 312 insertions, 20 deletions

diff --git a/drivers/counter/counter-chrdev.c b/drivers/counter/counter-chrdev.c
index 120879ee2e87..80acdf62794a 100644
--- a/drivers/counter/counter-chrdev.c
+++ b/drivers/counter/counter-chrdev.c
@@ -40,7 +40,11 @@ struct counter_comp_node {
 	a.signal_u32_read == b.signal_u32_read || \
 	a.device_u64_read == b.device_u64_read || \
 	a.count_u64_read == b.count_u64_read || \
-	a.signal_u64_read == b.signal_u64_read)
+	a.signal_u64_read == b.signal_u64_read || \
+	a.signal_array_u32_read == b.signal_array_u32_read || \
+	a.device_array_u64_read == b.device_array_u64_read || \
+	a.count_array_u64_read == b.count_array_u64_read || \
+	a.signal_array_u64_read == b.signal_array_u64_read)
 
 #define counter_comp_read_is_set(comp) \
 	(comp.action_read || \
@@ -52,7 +56,11 @@ struct counter_comp_node {
 	comp.signal_u32_read || \
 	comp.device_u64_read || \
 	comp.count_u64_read || \
-	comp.signal_u64_read)
+	comp.signal_u64_read || \
+	comp.signal_array_u32_read || \
+	comp.device_array_u64_read || \
+	comp.count_array_u64_read || \
+	comp.signal_array_u64_read)
 
 static ssize_t counter_chrdev_read(struct file *filp, char __user *buf,
 				   size_t len, loff_t *f_ps)
@@ -228,6 +236,31 @@ static int counter_disable_events(struct counter_device *const counter)
 	return err;
 }
 
+static int counter_get_ext(const struct counter_comp *const ext,
+			   const size_t num_ext, const size_t component_id,
+			   size_t *const ext_idx, size_t *const id)
+{
+	struct counter_array *element;
+
+	*id = 0;
+	for (*ext_idx = 0; *ext_idx < num_ext; (*ext_idx)++) {
+		if (*id == component_id)
+			return 0;
+
+		if (ext->type == COUNTER_COMP_ARRAY) {
+			element = ext->priv;
+
+			if (component_id - *id < element->length)
+				return 0;
+
+			*id += element->length;
+		} else
+			(*id)++;
+	}
+
+	return -EINVAL;
+}
+
 static int counter_add_watch(struct counter_device *const counter,
 			     const unsigned long arg)
 {
@@ -237,6 +270,7 @@ static int counter_add_watch(struct counter_device *const counter,
 	size_t parent, id;
 	struct counter_comp *ext;
 	size_t num_ext;
+	size_t ext_idx, ext_id;
 	int err = 0;
 
 	if (copy_from_user(&watch, uwatch, sizeof(watch)))
@@ -314,11 +348,11 @@ static int counter_add_watch(struct counter_device *const counter,
 		comp_node.comp.priv = counter->counts[parent].synapses + id;
 		break;
 	case COUNTER_COMPONENT_EXTENSION:
-		if (id >= num_ext)
-			return -EINVAL;
-		id = array_index_nospec(id, num_ext);
+		err = counter_get_ext(ext, num_ext, id, &ext_idx, &ext_id);
+		if (err < 0)
+			return err;
 
-		comp_node.comp = ext[id];
+		comp_node.comp = ext[ext_idx];
 		break;
 	default:
 		return -EINVAL;
@@ -451,14 +485,56 @@ void counter_chrdev_remove(struct counter_device *const counter)
 	kfifo_free(&counter->events);
 }
 
+static int counter_get_array_data(struct counter_device *const counter,
+				  const enum counter_scope scope,
+				  void *const parent,
+				  const struct counter_comp *const comp,
+				  const size_t idx, u64 *const value)
+{
+	const struct counter_array *const element = comp->priv;
+	u32 value_u32 = 0;
+	int ret;
+
+	switch (element->type) {
+	case COUNTER_COMP_SIGNAL_POLARITY:
+		if (scope != COUNTER_SCOPE_SIGNAL)
+			return -EINVAL;
+		ret = comp->signal_array_u32_read(counter, parent, idx,
+						  &value_u32);
+		*value = value_u32;
+		return ret;
+	case COUNTER_COMP_U64:
+		switch (scope) {
+		case COUNTER_SCOPE_DEVICE:
+			return comp->device_array_u64_read(counter, idx, value);
+		case COUNTER_SCOPE_SIGNAL:
+			return comp->signal_array_u64_read(counter, parent, idx,
+							   value);
+		case COUNTER_SCOPE_COUNT:
+			return comp->count_array_u64_read(counter, parent, idx,
+							  value);
+		default:
+			return -EINVAL;
+		}
+	default:
+		return -EINVAL;
+	}
+}
+
 static int counter_get_data(struct counter_device *const counter,
 			    const struct counter_comp_node *const comp_node,
 			    u64 *const value)
 {
 	const struct counter_comp *const comp = &comp_node->comp;
-	void *const parent = comp_node->parent;
+	const enum counter_scope scope = comp_node->component.scope;
+	const size_t id = comp_node->component.id;
+	struct counter_signal *const signal = comp_node->parent;
+	struct counter_count *const count = comp_node->parent;
 	u8 value_u8 = 0;
 	u32 value_u32 = 0;
+	const struct counter_comp *ext;
+	size_t num_ext;
+	size_t ext_idx, ext_id;
 	int ret;
 
 	if (comp_node->component.type == COUNTER_COMPONENT_NONE)
@@ -467,15 +543,15 @@ static int counter_get_data(struct counter_device *const counter,
 	switch (comp->type) {
 	case COUNTER_COMP_U8:
 	case COUNTER_COMP_BOOL:
-		switch (comp_node->component.scope) {
+		switch (scope) {
 		case COUNTER_SCOPE_DEVICE:
 			ret = comp->device_u8_read(counter, &value_u8);
 			break;
 		case COUNTER_SCOPE_SIGNAL:
-			ret = comp->signal_u8_read(counter, parent, &value_u8);
+			ret = comp->signal_u8_read(counter, signal, &value_u8);
 			break;
 		case COUNTER_SCOPE_COUNT:
-			ret = comp->count_u8_read(counter, parent, &value_u8);
+			ret = comp->count_u8_read(counter, count, &value_u8);
 			break;
 		default:
 			return -EINVAL;
@@ -488,16 +564,16 @@ static int counter_get_data(struct counter_device *const counter,
 	case COUNTER_COMP_COUNT_DIRECTION:
 	case COUNTER_COMP_COUNT_MODE:
 	case COUNTER_COMP_SIGNAL_POLARITY:
-		switch (comp_node->component.scope) {
+		switch (scope) {
 		case COUNTER_SCOPE_DEVICE:
 			ret = comp->device_u32_read(counter, &value_u32);
 			break;
 		case COUNTER_SCOPE_SIGNAL:
-			ret = comp->signal_u32_read(counter, parent,
+			ret = comp->signal_u32_read(counter, signal,
 						    &value_u32);
 			break;
 		case COUNTER_SCOPE_COUNT:
-			ret = comp->count_u32_read(counter, parent, &value_u32);
+			ret = comp->count_u32_read(counter, count, &value_u32);
 			break;
 		default:
 			return -EINVAL;
@@ -505,21 +581,43 @@ static int counter_get_data(struct counter_device *const counter,
 		*value = value_u32;
 		return ret;
 	case COUNTER_COMP_U64:
-		switch (comp_node->component.scope) {
+		switch (scope) {
 		case COUNTER_SCOPE_DEVICE:
 			return comp->device_u64_read(counter, value);
 		case COUNTER_SCOPE_SIGNAL:
-			return comp->signal_u64_read(counter, parent, value);
+			return comp->signal_u64_read(counter, signal, value);
 		case COUNTER_SCOPE_COUNT:
-			return comp->count_u64_read(counter, parent, value);
+			return comp->count_u64_read(counter, count, value);
 		default:
 			return -EINVAL;
 		}
 	case COUNTER_COMP_SYNAPSE_ACTION:
-		ret = comp->action_read(counter, parent, comp->priv,
-					&value_u32);
+		ret = comp->action_read(counter, count, comp->priv, &value_u32);
 		*value = value_u32;
 		return ret;
+	case COUNTER_COMP_ARRAY:
+		switch (scope) {
+		case COUNTER_SCOPE_DEVICE:
+			ext = counter->ext;
+			num_ext = counter->num_ext;
+			break;
+		case COUNTER_SCOPE_SIGNAL:
+			ext = signal->ext;
+			num_ext = signal->num_ext;
+			break;
+		case COUNTER_SCOPE_COUNT:
+			ext = count->ext;
+			num_ext = count->num_ext;
+			break;
+		default:
+			return -EINVAL;
+		}
+		ret = counter_get_ext(ext, num_ext, id, &ext_idx, &ext_id);
+		if (ret < 0)
+			return ret;
+
+		return counter_get_array_data(counter, scope, comp_node->parent,
+					      comp, id - ext_id, value);
 	default:
 		return -EINVAL;
 	}
diff --git a/drivers/counter/counter-sysfs.c b/drivers/counter/counter-sysfs.c
index b393da402e0b..b9efe66f9f8d 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;
 
@@ -500,6 +619,32 @@ 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;
 	}
@@ -609,6 +754,45 @@ 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++) {
+		/* Generate array element attribute name */
+		ext.name = devm_kasprintf(dev, GFP_KERNEL, "%s%zu", comp->name,
+					  idx);
+		if (!ext.name)
+			return -ENOMEM;
+
+		/* Allocate and configure array element */
+		element = devm_kzalloc(dev, sizeof(*element), GFP_KERNEL);
+		if (!element)
+			return -ENOMEM;
+		element->type = array->type;
+		element->avail = array->avail;
+		element->idx = idx;
+		ext.priv = element;
+
+		/* 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,
@@ -619,12 +803,22 @@ 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;
 	}