drm/tilcdc: Add support for external tda998x encoder

Add support for an external compontised DRM encoder. The external
encoder can be connected to tilcdc trough device tree graph binding.
The binding document for tilcdc has been updated. The current
implementation supports only tda998x encoder.

To be able to filter out the unsupported video modes the tilcdc driver
needs to hijack the external connectors helper functions. The tilcdc
installes new helper functions that are otherwise identical to
orignals, but the mode_valid() call-back check the mode first localy,
before calling the original call-back. The tilcdc dirver restores the
original helper functions before it is unbound from the external
device.

I got the idea and some lines of code from Jean-Francois Moine's
"drm/tilcdc: Change the interface with the tda998x driver"-patch.

Signed-off-by: Jyri Sarha <jsarha@ti.com>
Acked-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

1 files changed, 166 insertions, 0 deletions

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_external.c b/drivers/gpu/drm/tilcdc/tilcdc_external.c
new file mode 100644
index 000000000000..03acb4f99982
--- /dev/null
+++ b/drivers/gpu/drm/tilcdc/tilcdc_external.c
@@ -0,0 +1,166 @@
+/*
+ * Copyright (C) 2015 Texas Instruments
+ * Author: Jyri Sarha <jsarha@ti.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ */
+
+#include <linux/component.h>
+#include <linux/of_graph.h>
+
+#include "tilcdc_drv.h"
+#include "tilcdc_external.h"
+
+static const struct tilcdc_panel_info panel_info_tda998x = {
+		.ac_bias                = 255,
+		.ac_bias_intrpt         = 0,
+		.dma_burst_sz           = 16,
+		.bpp                    = 16,
+		.fdd                    = 0x80,
+		.tft_alt_mode           = 0,
+		.invert_pxl_clk		= 1,
+		.sync_edge              = 1,
+		.sync_ctrl              = 1,
+		.raster_order           = 0,
+};
+
+static int tilcdc_external_mode_valid(struct drm_connector *connector,
+				      struct drm_display_mode *mode)
+{
+	struct tilcdc_drm_private *priv = connector->dev->dev_private;
+	int ret, i;
+
+	ret = tilcdc_crtc_mode_valid(priv->crtc, mode);
+	if (ret != MODE_OK)
+		return ret;
+
+	for (i = 0; i < priv->num_connectors &&
+		     priv->connectors[i] != connector; i++)
+		;
+
+	BUG_ON(priv->connectors[i] != connector);
+	BUG_ON(!priv->connector_funcs[i]);
+
+	/* If the connector has its own mode_valid call it. */
+	if (!IS_ERR(priv->connector_funcs[i]) &&
+	    priv->connector_funcs[i]->mode_valid)
+		return priv->connector_funcs[i]->mode_valid(connector, mode);
+
+	return MODE_OK;
+}
+
+static int tilcdc_add_external_encoder(struct drm_device *dev, int *bpp,
+				       struct drm_connector *connector)
+{
+	struct tilcdc_drm_private *priv = dev->dev_private;
+	struct drm_connector_helper_funcs *connector_funcs;
+
+	priv->connectors[priv->num_connectors] = connector;
+	priv->encoders[priv->num_encoders++] = connector->encoder;
+
+	/* Only tda998x is supported at the moment. */
+	tilcdc_crtc_set_simulate_vesa_sync(priv->crtc, true);
+	tilcdc_crtc_set_panel_info(priv->crtc, &panel_info_tda998x);
+	*bpp = panel_info_tda998x.bpp;
+
+	connector_funcs = devm_kzalloc(dev->dev, sizeof(*connector_funcs),
+				       GFP_KERNEL);
+	if (!connector_funcs)
+		return -ENOMEM;
+
+	/* connector->helper_private contains always struct
+	 * connector_helper_funcs pointer. For tilcdc crtc to have a
+	 * say if a specific mode is Ok, we need to install our own
+	 * helper functions. In our helper functions we copy
+	 * everything else but use our own mode_valid() (above).
+	 */
+	if (connector->helper_private) {
+		priv->connector_funcs[priv->num_connectors] =
+			connector->helper_private;
+		*connector_funcs = *priv->connector_funcs[priv->num_connectors];
+	} else {
+		priv->connector_funcs[priv->num_connectors] = ERR_PTR(-ENOENT);
+	}
+	connector_funcs->mode_valid = tilcdc_external_mode_valid;
+	drm_connector_helper_add(connector, connector_funcs);
+	priv->num_connectors++;
+
+	dev_dbg(dev->dev, "External encoder '%s' connected\n",
+		connector->encoder->name);
+
+	return 0;
+}
+
+int tilcdc_add_external_encoders(struct drm_device *dev, int *bpp)
+{
+	struct tilcdc_drm_private *priv = dev->dev_private;
+	struct drm_connector *connector;
+	int num_internal_connectors = priv->num_connectors;
+
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
+		bool found = false;
+		int i, ret;
+
+		for (i = 0; i < num_internal_connectors; i++)
+			if (connector == priv->connectors[i])
+				found = true;
+		if (!found) {
+			ret = tilcdc_add_external_encoder(dev, bpp, connector);
+			if (ret)
+				return ret;
+		}
+	}
+	return 0;
+}
+
+void tilcdc_remove_external_encoders(struct drm_device *dev)
+{
+	struct tilcdc_drm_private *priv = dev->dev_private;
+	int i;
+
+	/* Restore the original helper functions, if any. */
+	for (i = 0; i < priv->num_connectors; i++)
+		if (IS_ERR(priv->connector_funcs[i]))
+			drm_connector_helper_add(priv->connectors[i], NULL);
+		else if (priv->connector_funcs[i])
+			drm_connector_helper_add(priv->connectors[i],
+						 priv->connector_funcs[i]);
+}
+
+static int dev_match_of(struct device *dev, void *data)
+{
+	return dev->of_node == data;
+}
+
+int tilcdc_get_external_components(struct device *dev,
+				   struct component_match **match)
+{
+	struct device_node *ep = NULL;
+	int count = 0;
+
+	while ((ep = of_graph_get_next_endpoint(dev->of_node, ep))) {
+		struct device_node *node;
+
+		node = of_graph_get_remote_port_parent(ep);
+		if (!node && !of_device_is_available(node)) {
+			of_node_put(node);
+			continue;
+		}
+
+		dev_dbg(dev, "Subdevice node '%s' found\n", node->name);
+		if (match)
+			component_match_add(dev, match, dev_match_of, node);
+		of_node_put(node);
+		count++;
+	}
+
+	if (count > 1) {
+		dev_err(dev, "Only one external encoder is supported\n");
+		return -EINVAL;
+	}
+
+	return count;
+}