gpio: swnode: allow referencing GPIO chips by firmware nodes

When doing a software node lookup, we require both the fwnode that
references a GPIO chip as well as the node associated with that chip to
be software nodes. However, we now allow referencing generic firmware
nodes from software nodes in driver core so we should allow the same in
GPIO core. Make the software node name check optional and dependent on
whether the referenced firmware node is a software node. If it's not,
just continue with the lookup.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

Author: Bartosz Golaszewski

drivers/gpio/gpiolib-swnode.c

@@ -31,7 +31,7 @@ static struct gpio_device *swnode_get_gpio_device(struct fwnode_handle *fwnode)
 
 	gdev_node = to_software_node(fwnode);
 	if (!gdev_node || !gdev_node->name)
-		return ERR_PTR(-EINVAL);
+		goto fwnode_lookup;
 
 	/*
 	 * Check for a special node that identifies undefined GPIOs, this is
@@ -41,6 +41,7 @@ static struct gpio_device *swnode_get_gpio_device(struct fwnode_handle *fwnode)
 	    !strcmp(gdev_node->name, GPIOLIB_SWNODE_UNDEFINED_NAME))
 		return ERR_PTR(-ENOENT);
 
+fwnode_lookup:
 	gdev = gpio_device_find_by_fwnode(fwnode);
 	return gdev ?: ERR_PTR(-EPROBE_DEFER);
 }