drm/bridge: Add ti-tfp410 DVI transmitter driver

Add very basic ti-tfp410 DVI transmitter driver. The only feature
separating this from a completely dummy bridge is the EDID read
support trough DDC I2C. Even that functionality should be in a
separate generic connector driver. However, because of missing DRM
infrastructure support the connector is implemented within the bridge
driver. Some tfp410 HW specific features may be added later if needed,
because there is a set of registers behind i2c if it is connected.

This implementation is tested against my new tilcdc bridge support
and it works with BeagleBone DVI-D Cape Rev A3. A DT binding document
is also updated.

Signed-off-by: Jyri Sarha <jsarha@ti.com>
Acked-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/display/bridge/ti,tfp410.txt

@@ -6,10 +6,15 @@ Required properties:
 
 Optional properties:
 - powerdown-gpios: power-down gpio
+- reg: I2C address. If and only if present the device node
+       should be placed into the i2c controller node where the
+       tfp410 i2c is connected to.
 
 Required nodes:
-- Video port 0 for DPI input
-- Video port 1 for DVI output
+- Video port 0 for DPI input [1].
+- Video port 1 for DVI output [1].
+
+[1]: Documentation/devicetree/bindings/media/video-interfaces.txt
 
 Example
 -------

drivers/gpu/drm/bridge/Kconfig

@@ -81,6 +81,13 @@ config DRM_TOSHIBA_TC358767
 	---help---
 	  Toshiba TC358767 eDP bridge chip driver.
 
+config DRM_TI_TFP410
+	tristate "TI TFP410 DVI/HDMI bridge"
+	depends on OF
+	select DRM_KMS_HELPER
+	---help---
+	  Texas Instruments TFP410 DVI/HDMI Transmitter driver
+
 source "drivers/gpu/drm/bridge/analogix/Kconfig"
 
 source "drivers/gpu/drm/bridge/adv7511/Kconfig"

drivers/gpu/drm/bridge/Makefile

@@ -11,3 +11,4 @@ obj-$(CONFIG_DRM_SII902X) += sii902x.o
 obj-$(CONFIG_DRM_TOSHIBA_TC358767) += tc358767.o
 obj-$(CONFIG_DRM_ANALOGIX_DP) += analogix/
 obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
+obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o

drivers/gpu/drm/bridge/ti-tfp410.c

@@ -0,0 +1,317 @@
+/*
+ * Copyright (C) 2016 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/module.h>
+#include <linux/of_graph.h>
+#include <linux/platform_device.h>
+#include <linux/i2c.h>
+
+#include <drm/drmP.h>
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_crtc.h>
+#include <drm/drm_crtc_helper.h>
+
+struct tfp410 {
+	struct drm_bridge	bridge;
+	struct drm_connector	connector;
+
+	struct i2c_adapter	*ddc;
+
+	struct device *dev;
+};
+
+static inline struct tfp410 *
+drm_bridge_to_tfp410(struct drm_bridge *bridge)
+{
+	return container_of(bridge, struct tfp410, bridge);
+}
+
+static inline struct tfp410 *
+drm_connector_to_tfp410(struct drm_connector *connector)
+{
+	return container_of(connector, struct tfp410, connector);
+}
+
+static int tfp410_get_modes(struct drm_connector *connector)
+{
+	struct tfp410 *dvi = drm_connector_to_tfp410(connector);
+	struct edid *edid;
+	int ret;
+
+	if (!dvi->ddc)
+		goto fallback;
+
+	edid = drm_get_edid(connector, dvi->ddc);
+	if (!edid) {
+		DRM_INFO("EDID read failed. Fallback to standard modes\n");
+		goto fallback;
+	}
+
+	drm_mode_connector_update_edid_property(connector, edid);
+
+	return drm_add_edid_modes(connector, edid);
+fallback:
+	/* No EDID, fallback on the XGA standard modes */
+	ret = drm_add_modes_noedid(connector, 1920, 1200);
+
+	/* And prefer a mode pretty much anything can handle */
+	drm_set_preferred_mode(connector, 1024, 768);
+
+	return ret;
+}
+
+static const struct drm_connector_helper_funcs tfp410_con_helper_funcs = {
+	.get_modes	= tfp410_get_modes,
+};
+
+static enum drm_connector_status
+tfp410_connector_detect(struct drm_connector *connector, bool force)
+{
+	struct tfp410 *dvi = drm_connector_to_tfp410(connector);
+
+	if (dvi->ddc) {
+		if (drm_probe_ddc(dvi->ddc))
+			return connector_status_connected;
+		else
+			return connector_status_disconnected;
+	}
+
+	return connector_status_unknown;
+}
+
+static const struct drm_connector_funcs tfp410_con_funcs = {
+	.dpms			= drm_atomic_helper_connector_dpms,
+	.detect			= tfp410_connector_detect,
+	.fill_modes		= drm_helper_probe_single_connector_modes,
+	.destroy		= drm_connector_cleanup,
+	.reset			= drm_atomic_helper_connector_reset,
+	.atomic_duplicate_state	= drm_atomic_helper_connector_duplicate_state,
+	.atomic_destroy_state	= drm_atomic_helper_connector_destroy_state,
+};
+
+static int tfp410_attach(struct drm_bridge *bridge)
+{
+	struct tfp410 *dvi = drm_bridge_to_tfp410(bridge);
+	int ret;
+
+	if (!bridge->encoder) {
+		dev_err(dvi->dev, "Missing encoder\n");
+		return -ENODEV;
+	}
+
+	drm_connector_helper_add(&dvi->connector,
+				 &tfp410_con_helper_funcs);
+	ret = drm_connector_init(bridge->dev, &dvi->connector,
+				 &tfp410_con_funcs, DRM_MODE_CONNECTOR_HDMIA);
+	if (ret) {
+		dev_err(dvi->dev, "drm_connector_init() failed: %d\n", ret);
+		return ret;
+	}
+
+	drm_mode_connector_attach_encoder(&dvi->connector,
+					  bridge->encoder);
+
+	return 0;
+}
+
+static const struct drm_bridge_funcs tfp410_bridge_funcs = {
+	.attach		= tfp410_attach,
+};
+
+static int tfp410_get_connector_ddc(struct tfp410 *dvi)
+{
+	struct device_node *ep = NULL, *connector_node = NULL;
+	struct device_node *ddc_phandle = NULL;
+	int ret = 0;
+
+	/* port@1 is the connector node */
+	ep = of_graph_get_endpoint_by_regs(dvi->dev->of_node, 1, -1);
+	if (!ep)
+		goto fail;
+
+	connector_node = of_graph_get_remote_port_parent(ep);
+	if (!connector_node)
+		goto fail;
+
+	ddc_phandle = of_parse_phandle(connector_node, "ddc-i2c-bus", 0);
+	if (!ddc_phandle)
+		goto fail;
+
+	dvi->ddc = of_get_i2c_adapter_by_node(ddc_phandle);
+	if (dvi->ddc)
+		dev_info(dvi->dev, "Connector's ddc i2c bus found\n");
+	else
+		ret = -EPROBE_DEFER;
+
+fail:
+	of_node_put(ep);
+	of_node_put(connector_node);
+	of_node_put(ddc_phandle);
+	return ret;
+}
+
+static int tfp410_init(struct device *dev)
+{
+	struct tfp410 *dvi;
+	int ret;
+
+	if (!dev->of_node) {
+		dev_err(dev, "device-tree data is missing\n");
+		return -ENXIO;
+	}
+
+	dvi = devm_kzalloc(dev, sizeof(*dvi), GFP_KERNEL);
+	if (!dvi)
+		return -ENOMEM;
+	dev_set_drvdata(dev, dvi);
+
+	dvi->bridge.funcs = &tfp410_bridge_funcs;
+	dvi->bridge.of_node = dev->of_node;
+	dvi->dev = dev;
+
+	ret = tfp410_get_connector_ddc(dvi);
+	if (ret)
+		goto fail;
+
+	ret = drm_bridge_add(&dvi->bridge);
+	if (ret) {
+		dev_err(dev, "drm_bridge_add() failed: %d\n", ret);
+		goto fail;
+	}
+
+	return 0;
+fail:
+	i2c_put_adapter(dvi->ddc);
+	return ret;
+}
+
+static int tfp410_fini(struct device *dev)
+{
+	struct tfp410 *dvi = dev_get_drvdata(dev);
+
+	drm_bridge_remove(&dvi->bridge);
+
+	if (dvi->ddc)
+		i2c_put_adapter(dvi->ddc);
+
+	return 0;
+}
+
+static int tfp410_probe(struct platform_device *pdev)
+{
+	return tfp410_init(&pdev->dev);
+}
+
+static int tfp410_remove(struct platform_device *pdev)
+{
+	return tfp410_fini(&pdev->dev);
+}
+
+static const struct of_device_id tfp410_match[] = {
+	{ .compatible = "ti,tfp410" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, tfp410_match);
+
+struct platform_driver tfp410_platform_driver = {
+	.probe	= tfp410_probe,
+	.remove	= tfp410_remove,
+	.driver	= {
+		.name		= "tfp410-bridge",
+		.of_match_table	= tfp410_match,
+	},
+};
+
+#if IS_ENABLED(CONFIG_I2C)
+/* There is currently no i2c functionality. */
+static int tfp410_i2c_probe(struct i2c_client *client,
+			    const struct i2c_device_id *id)
+{
+	int reg;
+
+	if (!client->dev.of_node ||
+	    of_property_read_u32(client->dev.of_node, "reg", &reg)) {
+		dev_err(&client->dev,
+			"Can't get i2c reg property from device-tree\n");
+		return -ENXIO;
+	}
+
+	return tfp410_init(&client->dev);
+}
+
+static int tfp410_i2c_remove(struct i2c_client *client)
+{
+	return tfp410_fini(&client->dev);
+}
+
+static const struct i2c_device_id tfp410_i2c_ids[] = {
+	{ "tfp410", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, tfp410_i2c_ids);
+
+static struct i2c_driver tfp410_i2c_driver = {
+	.driver = {
+		.name	= "tfp410",
+		.of_match_table = of_match_ptr(tfp410_match),
+	},
+	.id_table	= tfp410_i2c_ids,
+	.probe		= tfp410_i2c_probe,
+	.remove		= tfp410_i2c_remove,
+};
+#endif /* IS_ENABLED(CONFIG_I2C) */
+
+static struct {
+	uint i2c:1;
+	uint platform:1;
+}  tfp410_registered_driver;
+
+static int __init tfp410_module_init(void)
+{
+	int ret;
+
+#if IS_ENABLED(CONFIG_I2C)
+	ret = i2c_add_driver(&tfp410_i2c_driver);
+	if (ret)
+		pr_err("%s: registering i2c driver failed: %d",
+		       __func__, ret);
+	else
+		tfp410_registered_driver.i2c = 1;
+#endif
+
+	ret = platform_driver_register(&tfp410_platform_driver);
+	if (ret)
+		pr_err("%s: registering platform driver failed: %d",
+		       __func__, ret);
+	else
+		tfp410_registered_driver.platform = 1;
+
+	if (tfp410_registered_driver.i2c ||
+	    tfp410_registered_driver.platform)
+		return 0;
+
+	return ret;
+}
+module_init(tfp410_module_init);
+
+static void __exit tfp410_module_exit(void)
+{
+#if IS_ENABLED(CONFIG_I2C)
+	if (tfp410_registered_driver.i2c)
+		i2c_del_driver(&tfp410_i2c_driver);
+#endif
+	if (tfp410_registered_driver.platform)
+		platform_driver_unregister(&tfp410_platform_driver);
+}
+module_exit(tfp410_module_exit);
+
+MODULE_AUTHOR("Jyri Sarha <jsarha@ti.com>");
+MODULE_DESCRIPTION("TI TFP410 DVI bridge driver");
+MODULE_LICENSE("GPL");