gpio: sim: allow to define the active-low setting of a simulated hog

Add a new configfs attribute to the hog group allowing to configure the
active-low lookup flag for hogged lines. This will allow us to extend
tests to also cover the line config of hogs set up using software nodes.

Reviewed-by: Linus Walleij <linusw@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20260309-gpio-hog-fwnode-v2-6-4e61f3dbf06a@oss.qualcomm.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>

Author: Bartosz Golaszewski

drivers/gpio/gpio-sim.c

@@ -654,6 +654,7 @@ struct gpio_sim_hog {
 
 	char *name;
 	int dir;
+	bool active_low;
 };
 
 static struct gpio_sim_hog *to_gpio_sim_hog(struct config_item *item)
@@ -836,7 +837,7 @@ static int gpio_sim_bank_add_hogs(struct gpio_sim_bank *bank)
 		hog = line->hog;
 
 		gpios[0] = line->offset;
-		gpios[1] = 0;
+		gpios[1] = hog->active_low ? 1 : 0;
 
 		memset(properties, 0, sizeof(properties));
 
@@ -1315,9 +1316,46 @@ gpio_sim_hog_config_direction_store(struct config_item *item,
 
 CONFIGFS_ATTR(gpio_sim_hog_config_, direction);
 
+static ssize_t gpio_sim_hog_config_active_low_show(struct config_item *item,
+						   char *page)
+{
+	struct gpio_sim_hog *hog = to_gpio_sim_hog(item);
+	struct gpio_sim_device *dev = gpio_sim_hog_get_device(hog);
+
+	guard(mutex)(&dev->lock);
+
+	return sprintf(page, "%c\n", hog->active_low ? '1' : '0');
+}
+
+static ssize_t
+gpio_sim_hog_config_active_low_store(struct config_item *item,
+				     const char *page, size_t count)
+{
+	struct gpio_sim_hog *hog = to_gpio_sim_hog(item);
+	struct gpio_sim_device *dev = gpio_sim_hog_get_device(hog);
+	bool active_low;
+	int ret;
+
+	guard(mutex)(&dev->lock);
+
+	if (gpio_sim_device_is_live(dev))
+		return -EBUSY;
+
+	ret = kstrtobool(page, &active_low);
+	if (ret)
+		return ret;
+
+	hog->active_low = active_low;
+
+	return count;
+}
+
+CONFIGFS_ATTR(gpio_sim_hog_config_, active_low);
+
 static struct configfs_attribute *gpio_sim_hog_config_attrs[] = {
 	&gpio_sim_hog_config_attr_name,
 	&gpio_sim_hog_config_attr_direction,
+	&gpio_sim_hog_config_attr_active_low,
 	NULL
 };