[PATCH v2 04/10] gpio: aggregator: add read-write 'name' attribute

[Koichiro Den <koichiro.den@xxxxxxxxxxxxx>]

Previously, there is no way to assign names to GPIO lines exported
through an aggregator.

Allow users to set custom line names via a 'name' attribute.

Signed-off-by: Koichiro Den <koichiro.den@xxxxxxxxxxxxx>
---
 drivers/gpio/gpio-aggregator.c | 42 ++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/drivers/gpio/gpio-aggregator.c b/drivers/gpio/gpio-aggregator.c
index 76d3a8677308..3263d99bfe69 100644
--- a/drivers/gpio/gpio-aggregator.c
+++ b/drivers/gpio/gpio-aggregator.c
@@ -63,6 +63,8 @@ struct gpio_aggregator_line {
 	/* Line index within the aggregator device */
 	int idx;
 
+	/* Custom name for the virtual line */
+	char *name;
 	/* GPIO chip label or line name */
 	char *key;
 	/* Can be negative to indicate lookup by line name */
@@ -678,6 +680,44 @@ 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 sprintf(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)
 {
@@ -728,6 +768,7 @@ 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
 };
@@ -813,6 +854,7 @@ gpio_aggr_line_release(struct config_item *item)
 
 	aggr_line_del(aggr, line);
 	kfree(line->key);
+	kfree(line->name);
 	kfree(line);
 }
 
-- 
2.45.2