[PATCH 1/5] drm/panel: Add helper for reading DT rotation

Derek Basehore
2019-06-11T04:03:46Z

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

Signed-off-by: Derek Basehore <dbasehore@chromium.org>
---
drivers/gpu/drm/drm_panel.c | 41 +++++++++++++++++++++++++++++++++++++
include/drm/drm_panel.h | 7 +++++++
2 files changed, 48 insertions(+)

diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
index dbd5b873e8f2..3b689ce4a51a 100644
--- a/drivers/gpu/drm/drm_panel.c
+++ b/drivers/gpu/drm/drm_panel.c
@@ -172,6 +172,47 @@ 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 rotation of the panel using 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 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, int *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 8c738c0e6e9f..13631b2efbaa 100644
--- a/include/drm/drm_panel.h
+++ b/include/drm/drm_panel.h
@@ -197,11 +197,18 @@ int drm_panel_detach(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,
+ int *orientation);
#else
static inline struct drm_panel *of_drm_find_panel(const struct device_node *np)
{
return ERR_PTR(-ENODEV);
}
+int of_drm_get_panel_orientation(const struct device_node *np,
+ int *orientation)
+{
+ return -ENODEV;
+}
#endif

#endif
--
2.22.0.rc2.383.gf4fbbf30c2-goog