[PATCH 1/4] drm/panel: use fwnode based lookups for panel followers

[Jani Nikula]

Use firmware node based lookups for panel followers, to make the code
independent of OF and device tree, and make it work also for ACPI with
an appropriate _DSD.

ASL example:

	Package (0x02)
	{
		"panel", \_SB.PCI0.GFX0.LCD0
	}

Suggested-by: Heikki Krogerus <heikki.krogerus at linux.intel.com>
Cc: Neil Armstrong <neil.armstrong at linaro.org>
Cc: Jessica Zhang <jessica.zhang at oss.qualcomm.com>
Cc: Maxime Ripard <mripard at kernel.org>
Cc: Doug Anderson <dianders at chromium.org>
Cc: Lee Shawn C <shawn.c.lee at intel.com>
Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
 drivers/gpu/drm/drm_panel.c | 39 +++++++++++++++++++++++++++++--------
 1 file changed, 31 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
index fee65dc65979..3eb0a615f7a9 100644
--- a/drivers/gpu/drm/drm_panel.c
+++ b/drivers/gpu/drm/drm_panel.c
@@ -473,17 +473,40 @@ int of_drm_get_panel_orientation(const struct device_node *np,
 EXPORT_SYMBOL(of_drm_get_panel_orientation);
 #endif
 
-static struct drm_panel *of_find_panel(struct device *follower_dev)
+/* Find panel by fwnode */
+static struct drm_panel *find_panel_by_fwnode(const struct fwnode_handle *fwnode)
 {
-	struct device_node *panel_np;
 	struct drm_panel *panel;
 
-	panel_np = of_parse_phandle(follower_dev->of_node, "panel", 0);
-	if (!panel_np)
+	if (!fwnode_device_is_available(fwnode))
 		return ERR_PTR(-ENODEV);
 
-	panel = of_drm_find_panel(panel_np);
-	of_node_put(panel_np);
+	mutex_lock(&panel_lock);
+
+	list_for_each_entry(panel, &panel_list, list) {
+		if (dev_fwnode(panel->dev) == fwnode) {
+			mutex_unlock(&panel_lock);
+			return panel;
+		}
+	}
+
+	mutex_unlock(&panel_lock);
+
+	return ERR_PTR(-EPROBE_DEFER);
+}
+
+/* Find panel by follower device */
+static struct drm_panel *find_panel_by_dev(struct device *follower_dev)
+{
+	struct fwnode_handle *fwnode;
+	struct drm_panel *panel;
+
+	fwnode = fwnode_find_reference(dev_fwnode(follower_dev), "panel", 0);
+	if (IS_ERR_OR_NULL(fwnode))
+		return ERR_PTR(-ENODEV);
+
+	panel = find_panel_by_fwnode(fwnode);
+	fwnode_handle_put(fwnode);
 
 	return panel;
 }
@@ -506,7 +529,7 @@ bool drm_is_panel_follower(struct device *dev)
 	 * don't bother trying to parse it here. We just need to know if the
 	 * property is there.
 	 */
-	return of_property_present(dev->of_node, "panel");
+	return device_property_present(dev, "panel");
 }
 EXPORT_SYMBOL(drm_is_panel_follower);
 
@@ -536,7 +559,7 @@ int drm_panel_add_follower(struct device *follower_dev,
 	struct drm_panel *panel;
 	int ret;
 
-	panel = of_find_panel(follower_dev);
+	panel = find_panel_by_dev(follower_dev);
 	if (IS_ERR(panel))
 		return PTR_ERR(panel);
 
-- 
2.39.5