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Subject[PATCH v8 1/4] drm/panel: Add helper for reading DT rotation
Date
This adds a helper function for reading the rotation (panel
orientation) from the device tree.

Signed-off-by: Derek Basehore <dbasehore@chromium.org>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
---
drivers/gpu/drm/drm_panel.c | 43 +++++++++++++++++++++++++++++++++++++
include/drm/drm_panel.h | 9 ++++++++
2 files changed, 52 insertions(+)

diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
index 6b0bf42039cf..0909b53b74e6 100644
--- a/drivers/gpu/drm/drm_panel.c
+++ b/drivers/gpu/drm/drm_panel.c
@@ -264,6 +264,49 @@ 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. -EERROR otherwise.
+ */
+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

MODULE_AUTHOR("Thierry Reding <treding@nvidia.com>");
diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h
index 624bd15ecfab..d16158deacdc 100644
--- a/include/drm/drm_panel.h
+++ b/include/drm/drm_panel.h
@@ -34,6 +34,8 @@ struct drm_device;
struct drm_panel;
struct display_timing;

+enum drm_panel_orientation;
+
/**
* struct drm_panel_funcs - perform operations on a given panel
*
@@ -165,11 +167,18 @@ int drm_panel_get_modes(struct drm_panel *panel);

#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

#endif
--
2.23.0.351.gc4317032e6-goog
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