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 <[e-mail]>
Acked-by: Tomi Valkeinen <[e-mail]>

Documentation/devicetree/bindings/drm/tilcdc/tilcdc.txt

···
  - max-pixelclock: The maximum pixel clock that can be supported
    by the lcd controller in KHz.
 
+Optional nodes:
+
+ - port/ports: to describe a connection to an external encoder. The
+   binding follows Documentation/devicetree/bindings/graph.txt and
+   suppors a single port with a single endpoint.
+
 Example:
 
 	fb: fb@4830e000 {
···
 		interrupt-parent = <&intc>;
 		interrupts = <36>;
 		ti,hwmods = "lcdc";
+
+		port {
+			lcdc_0: endpoint@0 {
+				remote-endpoint = <&hdmi_0>;
+			};
+		};
+	};
+
+	tda19988: tda19988 {
+		compatible = "nxp,tda998x";
+		reg = <0x70>;
+
+		pinctrl-names = "default", "off";
+		pinctrl-0 = <&nxp_hdmi_bonelt_pins>;
+		pinctrl-1 = <&nxp_hdmi_bonelt_off_pins>;
+
+		port {
+			hdmi_0: endpoint@0 {
+				remote-endpoint = <&lcdc_0>;
+			};
+		};
 	};

drivers/gpu/drm/tilcdc/Makefile

···
 	tilcdc_crtc.o \
 	tilcdc_tfp410.o \
 	tilcdc_panel.o \
+	tilcdc_external.o \
 	tilcdc_drv.o
 
 obj-$(CONFIG_DRM_TILCDC)	+= tilcdc.o

drivers/gpu/drm/tilcdc/tilcdc_crtc.c

···
 
 	/* for deferred fb unref's: */
 	struct drm_flip_work unref_work;
+
+	/* Only set if an external encoder is connected */
+	bool simulate_vesa_sync;
 };
 #define to_tilcdc_crtc(x) container_of(x, struct tilcdc_crtc, base)
 
···
 		const struct drm_display_mode *mode,
 		struct drm_display_mode *adjusted_mode)
 {
+	struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
+
+	if (!tilcdc_crtc->simulate_vesa_sync)
+		return true;
+
+	/*
+	 * tilcdc does not generate VESA-compliant sync but aligns
+	 * VS on the second edge of HS instead of first edge.
+	 * We use adjusted_mode, to fixup sync by aligning both rising
+	 * edges and add HSKEW offset to fix the sync.
+	 */
+	adjusted_mode->hskew = mode->hsync_end - mode->hsync_start;
+	adjusted_mode->flags |= DRM_MODE_FLAG_HSKEW;
+
+	if (mode->flags & DRM_MODE_FLAG_NHSYNC) {
+		adjusted_mode->flags |= DRM_MODE_FLAG_PHSYNC;
+		adjusted_mode->flags &= ~DRM_MODE_FLAG_NHSYNC;
+	} else {
+		adjusted_mode->flags |= DRM_MODE_FLAG_NHSYNC;
+		adjusted_mode->flags &= ~DRM_MODE_FLAG_PHSYNC;
+	}
+
 	return true;
 }
 
···
 {
 	struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
 	tilcdc_crtc->info = info;
+}
+
+void tilcdc_crtc_set_simulate_vesa_sync(struct drm_crtc *crtc,
+					bool simulate_vesa_sync)
+{
+	struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
+
+	tilcdc_crtc->simulate_vesa_sync = simulate_vesa_sync;
 }
 
 void tilcdc_crtc_update_clk(struct drm_crtc *crtc)

drivers/gpu/drm/tilcdc/tilcdc_drv.c

···
 
 /* LCDC DRM driver, based on da8xx-fb */
 
+#include <linux/component.h>
+
 #include "tilcdc_drv.h"
 #include "tilcdc_regs.h"
 #include "tilcdc_tfp410.h"
 #include "tilcdc_panel.h"
+#include "tilcdc_external.h"
 
 #include "drm_fb_helper.h"
 
···
 		mod->funcs->modeset_init(mod, dev);
 	}
 
-	if ((priv->num_encoders == 0) || (priv->num_connectors == 0)) {
-		/* oh nos! */
-		dev_err(dev->dev, "no encoders/connectors found\n");
-		drm_mode_config_cleanup(dev);
-		return -ENXIO;
-	}
-
 	dev->mode_config.min_width = 0;
 	dev->mode_config.min_height = 0;
 	dev->mode_config.max_width = tilcdc_crtc_max_width(priv->crtc);
···
 static int tilcdc_unload(struct drm_device *dev)
 {
 	struct tilcdc_drm_private *priv = dev->dev_private;
+
+	tilcdc_remove_external_encoders(dev);
 
 	drm_fbdev_cma_fini(priv->fbdev);
 	drm_kms_helper_poll_fini(dev);
···
 	}
 
 	dev->dev_private = priv;
+
+	priv->is_componentized =
+		tilcdc_get_external_components(dev->dev, NULL) > 0;
 
 	priv->wq = alloc_ordered_workqueue("tilcdc", 0);
 	if (!priv->wq) {
···
 		goto fail_cpufreq_unregister;
 	}
 
+	platform_set_drvdata(pdev, dev);
+
+	if (priv->is_componentized) {
+		ret = component_bind_all(dev->dev, dev);
+		if (ret < 0)
+			goto fail_mode_config_cleanup;
+
+		ret = tilcdc_add_external_encoders(dev, &bpp);
+		if (ret < 0)
+			goto fail_component_cleanup;
+	}
+
+	if ((priv->num_encoders == 0) || (priv->num_connectors == 0)) {
+		dev_err(dev->dev, "no encoders/connectors found\n");
+		ret = -ENXIO;
+		goto fail_external_cleanup;
+	}
+
 	ret = drm_vblank_init(dev, 1);
 	if (ret < 0) {
 		dev_err(dev->dev, "failed to initialize vblank\n");
-		goto fail_mode_config_cleanup;
+		goto fail_external_cleanup;
 	}
 
 	pm_runtime_get_sync(dev->dev);
···
 		dev_err(dev->dev, "failed to install IRQ handler\n");
 		goto fail_vblank_cleanup;
 	}
-
-	platform_set_drvdata(pdev, dev);
-
 
 	list_for_each_entry(mod, &module_list, list) {
 		DBG("%s: preferred_bpp: %d", mod->name, mod->preferred_bpp);
···
 
 fail_mode_config_cleanup:
 	drm_mode_config_cleanup(dev);
+
+fail_component_cleanup:
+	if (priv->is_componentized)
+		component_unbind_all(dev->dev, dev);
+
+fail_external_cleanup:
+	tilcdc_remove_external_encoders(dev);
 
 fail_cpufreq_unregister:
 	pm_runtime_disable(dev->dev);
···
  * Platform driver:
  */
 
+static int tilcdc_bind(struct device *dev)
+{
+	return drm_platform_init(&tilcdc_driver, to_platform_device(dev));
+}
+
+static void tilcdc_unbind(struct device *dev)
+{
+	drm_put_dev(dev_get_drvdata(dev));
+}
+
+static const struct component_master_ops tilcdc_comp_ops = {
+	.bind = tilcdc_bind,
+	.unbind = tilcdc_unbind,
+};
+
 static int tilcdc_pdev_probe(struct platform_device *pdev)
 {
+	struct component_match *match = NULL;
+	int ret;
+
 	/* bail out early if no DT data: */
 	if (!pdev->dev.of_node) {
 		dev_err(&pdev->dev, "device-tree data is missing\n");
 		return -ENXIO;
 	}
 
-	return drm_platform_init(&tilcdc_driver, pdev);
+	ret = tilcdc_get_external_components(&pdev->dev, &match);
+	if (ret < 0)
+		return ret;
+	else if (ret == 0)
+		return drm_platform_init(&tilcdc_driver, pdev);
+	else
+		return component_master_add_with_match(&pdev->dev,
+						       &tilcdc_comp_ops,
+						       match);
 }
 
 static int tilcdc_pdev_remove(struct platform_device *pdev)
 {
-	drm_put_dev(platform_get_drvdata(pdev));
+	struct drm_device *ddev = dev_get_drvdata(&pdev->dev);
+	struct tilcdc_drm_private *priv = ddev->dev_private;
+
+	/* Check if a subcomponent has already triggered the unloading. */
+	if (!priv)
+		return 0;
+
+	if (priv->is_componentized)
+		component_master_del(&pdev->dev, &tilcdc_comp_ops);
+	else
+		drm_put_dev(platform_get_drvdata(pdev));
 
 	return 0;
 }

drivers/gpu/drm/tilcdc/tilcdc_drv.h

···
 
 	unsigned int num_connectors;
 	struct drm_connector *connectors[8];
+	const struct drm_connector_helper_funcs *connector_funcs[8];
+
+	bool is_componentized;
 };
 
 /* Sub-module for display.  Since we don't know at compile time what panels
···
 void tilcdc_crtc_update_clk(struct drm_crtc *crtc);
 void tilcdc_crtc_set_panel_info(struct drm_crtc *crtc,
 		const struct tilcdc_panel_info *info);
+void tilcdc_crtc_set_simulate_vesa_sync(struct drm_crtc *crtc,
+					bool simulate_vesa_sync);
 int tilcdc_crtc_mode_valid(struct drm_crtc *crtc, struct drm_display_mode *mode);
 int tilcdc_crtc_max_width(struct drm_crtc *crtc);
 

drivers/gpu/drm/tilcdc/tilcdc_external.c

···
+/*
+ * Copyright (C) 2015 Texas Instruments
+ * Author: Jyri Sarha <[e-mail]>
+ *
+ * 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;
+}

drivers/gpu/drm/tilcdc/tilcdc_external.h

···
+/*
+ * Copyright (C) 2015 Texas Instruments
+ * Author: Jyri Sarha <[e-mail]>
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __TILCDC_EXTERNAL_H__
+#define __TILCDC_EXTERNAL_H__
+
+int tilcdc_add_external_encoders(struct drm_device *dev, int *bpp);
+void tilcdc_remove_external_encoders(struct drm_device *dev);
+int tilcdc_get_external_components(struct device *dev,
+				   struct component_match **match);
+#endif /* __TILCDC_SLAVE_H__ */