OMAPDSS: output: Add set/unset device ops for omap_dss_output

An output entity represented by the struct omap_dss_output connects to a
omap_dss_device entity. Add functions to set or unset an output's device. This
is similar to how managers and devices were connected previously. An output can
connect to a device without being connected to a manager. However, the output
needs to eventually connect to a manager so that the connected panel can be
enabled.

Keep the omap_overlay_manager pointer in omap_dss_device for now to prevent
breaking things. This will be removed later when outputs are supported
completely.
Signed-off-by: Archit Taneja <archit@ti.com>

drivers/video/omap2/dss/output.c

@@ -16,6 +16,7 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 
@@ -24,6 +25,72 @@
 #include "dss.h"
 
 static LIST_HEAD(output_list);
+static DEFINE_MUTEX(output_lock);
+
+int omapdss_output_set_device(struct omap_dss_output *out,
+		struct omap_dss_device *dssdev)
+{
+	int r;
+
+	mutex_lock(&output_lock);
+
+	if (out->device) {
+		DSSERR("output already has device %s connected to it\n",
+			out->device->name);
+		r = -EINVAL;
+		goto err;
+	}
+
+	if (out->type != dssdev->type) {
+		DSSERR("output type and display type don't match\n");
+		r = -EINVAL;
+		goto err;
+	}
+
+	out->device = dssdev;
+	dssdev->output = out;
+
+	mutex_unlock(&output_lock);
+
+	return 0;
+err:
+	mutex_unlock(&output_lock);
+
+	return r;
+}
+EXPORT_SYMBOL(omapdss_output_set_device);
+
+int omapdss_output_unset_device(struct omap_dss_output *out)
+{
+	int r;
+
+	mutex_lock(&output_lock);
+
+	if (!out->device) {
+		DSSERR("output doesn't have a device connected to it\n");
+		r = -EINVAL;
+		goto err;
+	}
+
+	if (out->device->state != OMAP_DSS_DISPLAY_DISABLED) {
+		DSSERR("device %s is not disabled, cannot unset device\n",
+				out->device->name);
+		r = -EINVAL;
+		goto err;
+	}
+
+	out->device->output = NULL;
+	out->device = NULL;
+
+	mutex_unlock(&output_lock);
+
+	return 0;
+err:
+	mutex_unlock(&output_lock);
+
+	return r;
+}
+EXPORT_SYMBOL(omapdss_output_unset_device);
 
 void dss_register_output(struct omap_dss_output *out)
 {

include/video/omapdss.h

@@ -620,6 +620,7 @@ struct omap_dss_device {
 	enum omap_display_caps caps;
 
 	struct omap_overlay_manager *manager;
+	struct omap_dss_output *output;
 
 	enum omap_dss_display_state state;
 
@@ -731,6 +732,9 @@ int omap_dss_get_num_overlays(void);
 struct omap_overlay *omap_dss_get_overlay(int num);
 
 struct omap_dss_output *omap_dss_get_output(enum omap_dss_output_id id);
+int omapdss_output_set_device(struct omap_dss_output *out,
+		struct omap_dss_device *dssdev);
+int omapdss_output_unset_device(struct omap_dss_output *out);
 
 void omapdss_default_get_resolution(struct omap_dss_device *dssdev,
 		u16 *xres, u16 *yres);