[PATCH v4 5/9] gpio: aggregator: add 'name' attribute for custom GPIO line names

[Koichiro Den <koichiro.den@xxxxxxxxxxxxx>]

Previously, there was no way to assign names to GPIO lines exported
through the aggregator when the device was created via sysfs.

Allow users to set custom line names via a 'name' attribute and
expose them using swnode.

Signed-off-by: Koichiro Den <koichiro.den@xxxxxxxxxxxxx>
---
 drivers/gpio/gpio-aggregator.c | 84 ++++++++++++++++++++++++++++++++--
 1 file changed, 81 insertions(+), 3 deletions(-)

diff --git a/drivers/gpio/gpio-aggregator.c b/drivers/gpio/gpio-aggregator.c
index ec102453817b..692d90246674 100644
--- a/drivers/gpio/gpio-aggregator.c
+++ b/drivers/gpio/gpio-aggregator.c
@@ -61,6 +61,8 @@ struct gpio_aggregator_line {
 	/* Line index within the aggregator device */
 	unsigned int idx;
 
+	/* Custom name for the virtual line */
+	const char *name;
 	/* GPIO chip label or line name */
 	const char *key;
 	/* Can be negative to indicate lookup by line name */
@@ -530,10 +532,40 @@ to_gpio_aggregator_line(struct config_item *item)
 	return container_of(group, struct gpio_aggregator_line, group);
 }
 
+static struct fwnode_handle *aggr_make_device_swnode(struct gpio_aggregator *aggr)
+{
+	const char **line_names __free(kfree) = NULL;
+	struct property_entry properties[2];
+	struct gpio_aggregator_line *line;
+	size_t num_lines;
+	int n = 0;
+
+	memset(properties, 0, sizeof(properties));
+
+	num_lines = aggr_count_lines(aggr);
+	if (num_lines == 0)
+		return NULL;
+
+	line_names = kcalloc(num_lines, sizeof(*line_names), GFP_KERNEL);
+	if (!line_names)
+		return ERR_PTR(-ENOMEM);
+
+	/* The list is always sorted as new elements are inserted in order. */
+	list_for_each_entry(line, &aggr->list_head, entry)
+		line_names[n++] = line->name ?: "";
+
+	properties[0] = PROPERTY_ENTRY_STRING_ARRAY_LEN(
+					"gpio-line-names",
+					line_names, num_lines);
+
+	return fwnode_create_software_node(properties, NULL);
+}
+
 static int aggr_activate(struct gpio_aggregator *aggr)
 {
 	struct platform_device_info pdevinfo;
 	struct gpio_aggregator_line *line;
+	struct fwnode_handle *swnode;
 	unsigned int n = 0;
 	int ret = 0;
 
@@ -545,9 +577,14 @@ static int aggr_activate(struct gpio_aggregator *aggr)
 	if (!aggr->lookups)
 		return -ENOMEM;
 
+	swnode = aggr_make_device_swnode(aggr);
+	if (IS_ERR(swnode))
+		goto err_remove_lookups;
+
 	memset(&pdevinfo, 0, sizeof(pdevinfo));
 	pdevinfo.name = DRV_NAME;
 	pdevinfo.id = aggr->id;
+	pdevinfo.fwnode = swnode;
 
 	/* The list is always sorted as new elements are inserted in order. */
 	list_for_each_entry(line, &aggr->list_head, entry) {
@@ -559,7 +596,7 @@ static int aggr_activate(struct gpio_aggregator *aggr)
 		 */
 		if (!line->key || line->idx != n) {
 			ret = -EINVAL;
-			goto err_remove_lookups;
+			goto err_remove_swnode;
 		}
 
 		if (line->offset < 0)
@@ -567,13 +604,13 @@ static int aggr_activate(struct gpio_aggregator *aggr)
 		else
 			ret = aggr_add_gpio(aggr, line->key, line->offset, &n);
 		if (ret)
-			goto err_remove_lookups;
+			goto err_remove_swnode;
 	}
 
 	aggr->lookups->dev_id = kasprintf(GFP_KERNEL, "%s.%d", DRV_NAME, aggr->id);
 	if (!aggr->lookups->dev_id) {
 		ret = -ENOMEM;
-		goto err_remove_lookups;
+		goto err_remove_swnode;
 	}
 
 	gpiod_add_lookup_table(aggr->lookups);
@@ -587,6 +624,8 @@ static int aggr_activate(struct gpio_aggregator *aggr)
 err_remove_lookup_table:
 	kfree(aggr->lookups->dev_id);
 	gpiod_remove_lookup_table(aggr->lookups);
+err_remove_swnode:
+	fwnode_remove_software_node(swnode);
 err_remove_lookups:
 	kfree(aggr->lookups);
 
@@ -658,6 +697,43 @@ gpio_aggr_line_key_store(struct config_item *item, const char *page,
 }
 CONFIGFS_ATTR(gpio_aggr_line_, key);
 
+static ssize_t
+gpio_aggr_line_name_show(struct config_item *item, char *page)
+{
+	struct gpio_aggregator_line *line = to_gpio_aggregator_line(item);
+	struct gpio_aggregator *aggr = line->parent;
+
+	guard(mutex)(&aggr->lock);
+
+	return sysfs_emit(page, "%s\n", line->name ?: "");
+}
+
+static ssize_t
+gpio_aggr_line_name_store(struct config_item *item, const char *page,
+			  size_t count)
+{
+	struct gpio_aggregator_line *line = to_gpio_aggregator_line(item);
+	struct gpio_aggregator *aggr = line->parent;
+
+	char *name __free(kfree) = kstrndup(skip_spaces(page), count,
+					    GFP_KERNEL);
+	if (!name)
+		return -ENOMEM;
+
+	strim(name);
+
+	guard(mutex)(&aggr->lock);
+
+	if (aggr_is_active(aggr))
+		return -EBUSY;
+
+	kfree(line->name);
+	line->name = no_free_ptr(name);
+
+	return count;
+}
+CONFIGFS_ATTR(gpio_aggr_line_, name);
+
 static ssize_t
 gpio_aggr_line_offset_show(struct config_item *item, char *page)
 {
@@ -707,6 +783,7 @@ CONFIGFS_ATTR(gpio_aggr_line_, offset);
 
 static struct configfs_attribute *gpio_aggr_line_attrs[] = {
 	&gpio_aggr_line_attr_key,
+	&gpio_aggr_line_attr_name,
 	&gpio_aggr_line_attr_offset,
 	NULL
 };
@@ -795,6 +872,7 @@ gpio_aggr_line_release(struct config_item *item)
 
 	aggr_line_del(aggr, line);
 	kfree(line->key);
+	kfree(line->name);
 	kfree(line);
 }
 
-- 
2.45.2