drm/panel: Add helper for reading DT rotation

This adds a helper function for reading the rotation (panel
orientation) from the device tree.

Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Derek Basehore <dbasehore@chromium.org>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200813215609.28643-2-digetx@gmail.com

diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
index ba11c36..f634371 100644 (file)
--- a/drivers/gpu/drm/drm_panel.c
+++ b/drivers/gpu/drm/drm_panel.c
@@ -260,6 +260,49 @@ struct drm_panel *of_drm_find_panel(const struct device_node *np)
        return ERR_PTR(-EPROBE_DEFER);
 }
 EXPORT_SYMBOL(of_drm_find_panel);
+
+/**
+ * of_drm_get_panel_orientation - look up the orientation of the panel through
+ * the "rotation" binding from a device tree node
+ * @np: device tree node of the panel
+ * @orientation: orientation enum to be filled in
+ *
+ * Looks up the rotation of a panel in the device tree. The orientation of the
+ * panel is expressed as a property name "rotation" in the device tree. The
+ * rotation in the device tree is counter clockwise.
+ *
+ * Return: 0 when a valid rotation value (0, 90, 180, or 270) is read or the
+ * rotation property doesn't exist. Return a negative error code on failure.
+ */
+int of_drm_get_panel_orientation(const struct device_node *np,
+                                enum drm_panel_orientation *orientation)
+{
+       int rotation, ret;
+
+       ret = of_property_read_u32(np, "rotation", &rotation);
+       if (ret == -EINVAL) {
+               /* Don't return an error if there's no rotation property. */
+               *orientation = DRM_MODE_PANEL_ORIENTATION_UNKNOWN;
+               return 0;
+       }
+
+       if (ret < 0)
+               return ret;
+
+       if (rotation == 0)
+               *orientation = DRM_MODE_PANEL_ORIENTATION_NORMAL;
+       else if (rotation == 90)
+               *orientation = DRM_MODE_PANEL_ORIENTATION_RIGHT_UP;
+       else if (rotation == 180)
+               *orientation = DRM_MODE_PANEL_ORIENTATION_BOTTOM_UP;
+       else if (rotation == 270)
+               *orientation = DRM_MODE_PANEL_ORIENTATION_LEFT_UP;
+       else
+               return -EINVAL;
+
+       return 0;
+}
+EXPORT_SYMBOL(of_drm_get_panel_orientation);
 #endif
 
 #if IS_REACHABLE(CONFIG_BACKLIGHT_CLASS_DEVICE)

diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h
index 45a1b5a..33605c3 100644 (file)
--- a/include/drm/drm_panel.h
+++ b/include/drm/drm_panel.h
@@ -35,6 +35,8 @@ struct drm_device;
 struct drm_panel;
 struct display_timing;
 
+enum drm_panel_orientation;
+
 /**
  * struct drm_panel_funcs - perform operations on a given panel
  *
@@ -188,11 +190,19 @@ int drm_panel_get_modes(struct drm_panel *panel, struct drm_connector *connector
 
 #if defined(CONFIG_OF) && defined(CONFIG_DRM_PANEL)
 struct drm_panel *of_drm_find_panel(const struct device_node *np);
+int of_drm_get_panel_orientation(const struct device_node *np,
+                                enum drm_panel_orientation *orientation);
 #else
 static inline struct drm_panel *of_drm_find_panel(const struct device_node *np)
 {
        return ERR_PTR(-ENODEV);
 }
+
+static inline int of_drm_get_panel_orientation(const struct device_node *np,
+                                              enum drm_panel_orientation *orientation)
+{
+       return -ENODEV;
+}
 #endif
 
 #if IS_ENABLED(CONFIG_DRM_PANEL) && (IS_BUILTIN(CONFIG_BACKLIGHT_CLASS_DEVICE) || \