drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Driver for MegaChips STDP4028 with GE B850v3 firmware (LVDS-DP)
  * Driver for MegaChips STDP2690 with GE B850v3 firmware (DP-DP++)

  * Copyright (c) 2017, Collabora Ltd.
  * Copyright (c) 2017, General Electric Company


  * This driver creates a drm_bridge and a drm_connector for the LVDS to DP++
  * display bridge of the GE B850v3. There are two physical bridges on the video
  * signal pipeline: a STDP4028(LVDS to DP) and a STDP2690(DP to DP++). The
  * physical bridges are automatically configured by the input video signal, and
  * the driver has no access to the video processing pipeline. The driver is
  * only needed to read EDID from the STDP2690 and to handle HPD events from the
  * STDP4028. The driver communicates with both bridges over i2c. The video
  * signal pipeline is as follows:
  *
  *   Host -> LVDS|--(STDP4028)--|DP -> DP|--(STDP2690)--|DP++ -> Video output
  */

 #include <linux/i2c.h>
 #include <linux/module.h>
 #include <linux/of.h>

 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_bridge.h>
 #include <drm/drm_edid.h>
 #include <drm/drm_print.h>
 #include <drm/drm_probe_helper.h>

 #define EDID_EXT_BLOCK_CNT 0x7E

 #define STDP4028_IRQ_OUT_CONF_REG 0x02
 #define STDP4028_DPTX_IRQ_EN_REG 0x3C
 #define STDP4028_DPTX_IRQ_STS_REG 0x3D
 #define STDP4028_DPTX_STS_REG 0x3E

 #define STDP4028_DPTX_DP_IRQ_EN 0x1000

 #define STDP4028_DPTX_HOTPLUG_IRQ_EN 0x0400
 #define STDP4028_DPTX_LINK_CH_IRQ_EN 0x2000
 #define STDP4028_DPTX_IRQ_CONFIG \
 		(STDP4028_DPTX_LINK_CH_IRQ_EN | STDP4028_DPTX_HOTPLUG_IRQ_EN)

 #define STDP4028_DPTX_HOTPLUG_STS 0x0200
 #define STDP4028_DPTX_LINK_STS 0x1000
 #define STDP4028_CON_STATE_CONNECTED \
 		(STDP4028_DPTX_HOTPLUG_STS | STDP4028_DPTX_LINK_STS)

 #define STDP4028_DPTX_HOTPLUG_CH_STS 0x0400
 #define STDP4028_DPTX_LINK_CH_STS 0x2000
 #define STDP4028_DPTX_IRQ_CLEAR \
 		(STDP4028_DPTX_LINK_CH_STS | STDP4028_DPTX_HOTPLUG_CH_STS)

 static DEFINE_MUTEX(ge_b850v3_lvds_dev_mutex);

 struct ge_b850v3_lvds {
 	struct drm_connector connector;
 	struct drm_bridge bridge;
 	struct i2c_client *stdp4028_i2c;
 	struct i2c_client *stdp2690_i2c;
 };

 static struct ge_b850v3_lvds *ge_b850v3_lvds_ptr;

 static int stdp2690_read_block(void *context, u8 *buf, unsigned int block, size_t len)
 {
 	struct i2c_client *client = context;
 	struct i2c_adapter *adapter = client->adapter;
 	unsigned char start = block * EDID_LENGTH;

 	struct i2c_msg msgs[] = {
 		{
 			.addr	= client->addr,
 			.flags	= 0,
 			.len	= 1,
 			.buf	= &start,
 		}, {
 			.addr	= client->addr,
 			.flags	= I2C_M_RD,
 			.len	= len,
 			.buf	= buf,
 		}
 	};

 	if (i2c_transfer(adapter, msgs, 2) != 2)
 		return -1;

 	return 0;
 }

 static const struct drm_edid *ge_b850v3_lvds_edid_read(struct drm_bridge *bridge,
 						       struct drm_connector *connector)
 {
 	struct i2c_client *client;

 	client = ge_b850v3_lvds_ptr->stdp2690_i2c;

 	return drm_edid_read_custom(connector, stdp2690_read_block, client);
 }

 static int ge_b850v3_lvds_get_modes(struct drm_connector *connector)
 {
 	const struct drm_edid *drm_edid;
 	int num_modes;

 	drm_edid = ge_b850v3_lvds_edid_read(&ge_b850v3_lvds_ptr->bridge, connector);

 	drm_edid_connector_update(connector, drm_edid);
 	num_modes = drm_edid_connector_add_modes(connector);
 	drm_edid_free(drm_edid);

 	return num_modes;
 }

 static enum drm_mode_status ge_b850v3_lvds_mode_valid(
 		struct drm_connector *connector, struct drm_display_mode *mode)
 {
 	return MODE_OK;
 }

 static const struct
 drm_connector_helper_funcs ge_b850v3_lvds_connector_helper_funcs = {
 	.get_modes = ge_b850v3_lvds_get_modes,
 	.mode_valid = ge_b850v3_lvds_mode_valid,
 };

 static enum drm_connector_status ge_b850v3_lvds_bridge_detect(struct drm_bridge *bridge)
 {
 	struct i2c_client *stdp4028_i2c =
 			ge_b850v3_lvds_ptr->stdp4028_i2c;
 	s32 link_state;

 	link_state = i2c_smbus_read_word_data(stdp4028_i2c,
 					      STDP4028_DPTX_STS_REG);

 	if (link_state == STDP4028_CON_STATE_CONNECTED)
 		return connector_status_connected;

 	if (link_state == 0)
 		return connector_status_disconnected;

 	return connector_status_unknown;
 }

 static enum drm_connector_status ge_b850v3_lvds_detect(struct drm_connector *connector,
 						       bool force)
 {
 	return ge_b850v3_lvds_bridge_detect(&ge_b850v3_lvds_ptr->bridge);
 }

 static const struct drm_connector_funcs ge_b850v3_lvds_connector_funcs = {
 	.fill_modes = drm_helper_probe_single_connector_modes,
 	.detect = ge_b850v3_lvds_detect,
 	.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 ge_b850v3_lvds_create_connector(struct drm_bridge *bridge)
 {
 	struct drm_connector *connector = &ge_b850v3_lvds_ptr->connector;
 	int ret;

 	connector->polled = DRM_CONNECTOR_POLL_HPD;

 	drm_connector_helper_add(connector,
 				 &ge_b850v3_lvds_connector_helper_funcs);

 	ret = drm_connector_init(bridge->dev, connector,
 				 &ge_b850v3_lvds_connector_funcs,
 				 DRM_MODE_CONNECTOR_DisplayPort);
 	if (ret) {
 		DRM_ERROR("Failed to initialize connector with drm\n");
 		return ret;
 	}

 	return drm_connector_attach_encoder(connector, bridge->encoder);
 }

 static irqreturn_t ge_b850v3_lvds_irq_handler(int irq, void *dev_id)
 {
 	struct i2c_client *stdp4028_i2c
 			= ge_b850v3_lvds_ptr->stdp4028_i2c;

 	i2c_smbus_write_word_data(stdp4028_i2c,
 				  STDP4028_DPTX_IRQ_STS_REG,
 				  STDP4028_DPTX_IRQ_CLEAR);

 	if (ge_b850v3_lvds_ptr->bridge.dev)
 		drm_kms_helper_hotplug_event(ge_b850v3_lvds_ptr->bridge.dev);

 	return IRQ_HANDLED;
 }

 static int ge_b850v3_lvds_attach(struct drm_bridge *bridge,
 				 enum drm_bridge_attach_flags flags)
 {
 	struct i2c_client *stdp4028_i2c
 			= ge_b850v3_lvds_ptr->stdp4028_i2c;

 	/* Configures the bridge to re-enable interrupts after each ack. */
 	i2c_smbus_write_word_data(stdp4028_i2c,
 				  STDP4028_IRQ_OUT_CONF_REG,
 				  STDP4028_DPTX_DP_IRQ_EN);

 	/* Enable interrupts */
 	i2c_smbus_write_word_data(stdp4028_i2c,
 				  STDP4028_DPTX_IRQ_EN_REG,
 				  STDP4028_DPTX_IRQ_CONFIG);

 	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)
 		return 0;

 	return ge_b850v3_lvds_create_connector(bridge);
 }

 static const struct drm_bridge_funcs ge_b850v3_lvds_funcs = {
 	.attach = ge_b850v3_lvds_attach,
 	.detect = ge_b850v3_lvds_bridge_detect,
 	.edid_read = ge_b850v3_lvds_edid_read,
 };

 static int ge_b850v3_lvds_init(struct device *dev)
 {
 	mutex_lock(&ge_b850v3_lvds_dev_mutex);

 	if (ge_b850v3_lvds_ptr)
 		goto success;

 	ge_b850v3_lvds_ptr = devm_kzalloc(dev,
 					  sizeof(*ge_b850v3_lvds_ptr),
 					  GFP_KERNEL);

 	if (!ge_b850v3_lvds_ptr) {
 		mutex_unlock(&ge_b850v3_lvds_dev_mutex);
 		return -ENOMEM;
 	}

 success:
 	mutex_unlock(&ge_b850v3_lvds_dev_mutex);
 	return 0;
 }

 static void ge_b850v3_lvds_remove(void)
 {
 	mutex_lock(&ge_b850v3_lvds_dev_mutex);
 	/*
 	 * This check is to avoid both the drivers
 	 * removing the bridge in their remove() function
 	 */
 	if (!ge_b850v3_lvds_ptr ||
 	    !ge_b850v3_lvds_ptr->stdp2690_i2c ||
 		!ge_b850v3_lvds_ptr->stdp4028_i2c)
 		goto out;

 	drm_bridge_remove(&ge_b850v3_lvds_ptr->bridge);

 	ge_b850v3_lvds_ptr = NULL;
 out:
 	mutex_unlock(&ge_b850v3_lvds_dev_mutex);
 }

 static int ge_b850v3_register(void)
 {
 	struct i2c_client *stdp4028_i2c = ge_b850v3_lvds_ptr->stdp4028_i2c;
 	struct device *dev = &stdp4028_i2c->dev;

 	/* drm bridge initialization */
 	ge_b850v3_lvds_ptr->bridge.funcs = &ge_b850v3_lvds_funcs;
 	ge_b850v3_lvds_ptr->bridge.ops = DRM_BRIDGE_OP_DETECT |
 					 DRM_BRIDGE_OP_EDID;
 	ge_b850v3_lvds_ptr->bridge.type = DRM_MODE_CONNECTOR_DisplayPort;
 	ge_b850v3_lvds_ptr->bridge.of_node = dev->of_node;
 	drm_bridge_add(&ge_b850v3_lvds_ptr->bridge);

 	/* Clear pending interrupts since power up. */
 	i2c_smbus_write_word_data(stdp4028_i2c,
 				  STDP4028_DPTX_IRQ_STS_REG,
 				  STDP4028_DPTX_IRQ_CLEAR);

 	if (!stdp4028_i2c->irq)
 		return 0;

 	return devm_request_threaded_irq(&stdp4028_i2c->dev,
 			stdp4028_i2c->irq, NULL,
 			ge_b850v3_lvds_irq_handler,
 			IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
 			"ge-b850v3-lvds-dp", ge_b850v3_lvds_ptr);
 }

 static int stdp4028_ge_b850v3_fw_probe(struct i2c_client *stdp4028_i2c)
 {
 	struct device *dev = &stdp4028_i2c->dev;
 	int ret;

 	ret = ge_b850v3_lvds_init(dev);

 	if (ret)
 		return ret;

 	ge_b850v3_lvds_ptr->stdp4028_i2c = stdp4028_i2c;
 	i2c_set_clientdata(stdp4028_i2c, ge_b850v3_lvds_ptr);

 	/* Only register after both bridges are probed */
 	if (!ge_b850v3_lvds_ptr->stdp2690_i2c)
 		return 0;

 	return ge_b850v3_register();
 }

 static void stdp4028_ge_b850v3_fw_remove(struct i2c_client *stdp4028_i2c)
 {
 	ge_b850v3_lvds_remove();
 }

 static const struct i2c_device_id stdp4028_ge_b850v3_fw_i2c_table[] = {
 	{"stdp4028_ge_fw", 0},
 	{},
 };
 MODULE_DEVICE_TABLE(i2c, stdp4028_ge_b850v3_fw_i2c_table);

 static const struct of_device_id stdp4028_ge_b850v3_fw_match[] = {
 	{ .compatible = "megachips,stdp4028-ge-b850v3-fw" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, stdp4028_ge_b850v3_fw_match);

 static struct i2c_driver stdp4028_ge_b850v3_fw_driver = {
 	.id_table	= stdp4028_ge_b850v3_fw_i2c_table,
 	.probe		= stdp4028_ge_b850v3_fw_probe,
 	.remove		= stdp4028_ge_b850v3_fw_remove,
 	.driver		= {
 		.name		= "stdp4028-ge-b850v3-fw",
 		.of_match_table = stdp4028_ge_b850v3_fw_match,
 	},
 };

 static int stdp2690_ge_b850v3_fw_probe(struct i2c_client *stdp2690_i2c)
 {
 	struct device *dev = &stdp2690_i2c->dev;
 	int ret;

 	ret = ge_b850v3_lvds_init(dev);

 	if (ret)
 		return ret;

 	ge_b850v3_lvds_ptr->stdp2690_i2c = stdp2690_i2c;
 	i2c_set_clientdata(stdp2690_i2c, ge_b850v3_lvds_ptr);

 	/* Only register after both bridges are probed */
 	if (!ge_b850v3_lvds_ptr->stdp4028_i2c)
 		return 0;

 	return ge_b850v3_register();
 }

 static void stdp2690_ge_b850v3_fw_remove(struct i2c_client *stdp2690_i2c)
 {
 	ge_b850v3_lvds_remove();
 }

 static const struct i2c_device_id stdp2690_ge_b850v3_fw_i2c_table[] = {
 	{"stdp2690_ge_fw", 0},
 	{},
 };
 MODULE_DEVICE_TABLE(i2c, stdp2690_ge_b850v3_fw_i2c_table);

 static const struct of_device_id stdp2690_ge_b850v3_fw_match[] = {
 	{ .compatible = "megachips,stdp2690-ge-b850v3-fw" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, stdp2690_ge_b850v3_fw_match);

 static struct i2c_driver stdp2690_ge_b850v3_fw_driver = {
 	.id_table	= stdp2690_ge_b850v3_fw_i2c_table,
 	.probe		= stdp2690_ge_b850v3_fw_probe,
 	.remove		= stdp2690_ge_b850v3_fw_remove,
 	.driver		= {
 		.name		= "stdp2690-ge-b850v3-fw",
 		.of_match_table = stdp2690_ge_b850v3_fw_match,
 	},
 };

 static int __init stdpxxxx_ge_b850v3_init(void)
 {
 	int ret;

 	ret = i2c_add_driver(&stdp4028_ge_b850v3_fw_driver);
 	if (ret)
 		return ret;

 	ret = i2c_add_driver(&stdp2690_ge_b850v3_fw_driver);
 	if (ret)
 		i2c_del_driver(&stdp4028_ge_b850v3_fw_driver);

 	return ret;
 }
 module_init(stdpxxxx_ge_b850v3_init);

 static void __exit stdpxxxx_ge_b850v3_exit(void)
 {
 	i2c_del_driver(&stdp2690_ge_b850v3_fw_driver);
 	i2c_del_driver(&stdp4028_ge_b850v3_fw_driver);
 }
 module_exit(stdpxxxx_ge_b850v3_exit);

 MODULE_AUTHOR("Peter Senna Tschudin <peter.senna@collabora.com>");
 MODULE_AUTHOR("Martyn Welch <martyn.welch@collabora.co.uk>");
 MODULE_DESCRIPTION("GE LVDS to DP++ display bridge)");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Driver for MegaChips STDP4028 with GE B850v3 firmware (LVDS-DP)
	* Driver for MegaChips STDP2690 with GE B850v3 firmware (DP-DP++)

	* Copyright (c) 2017, Collabora Ltd.
	* Copyright (c) 2017, General Electric Company


	* This driver creates a drm_bridge and a drm_connector for the LVDS to DP++
	* display bridge of the GE B850v3. There are two physical bridges on the video
	* signal pipeline: a STDP4028(LVDS to DP) and a STDP2690(DP to DP++). The
	* physical bridges are automatically configured by the input video signal, and
	* the driver has no access to the video processing pipeline. The driver is
	* only needed to read EDID from the STDP2690 and to handle HPD events from the
	* STDP4028. The driver communicates with both bridges over i2c. The video
	* signal pipeline is as follows:
	*
	* Host -> LVDS\|--(STDP4028)--\|DP -> DP\|--(STDP2690)--\|DP++ -> Video output
	*/

	#include <linux/i2c.h>
	#include <linux/module.h>
	#include <linux/of.h>

	#include <drm/drm_atomic.h>
	#include <drm/drm_atomic_helper.h>
	#include <drm/drm_bridge.h>
	#include <drm/drm_edid.h>
	#include <drm/drm_print.h>
	#include <drm/drm_probe_helper.h>

	#define EDID_EXT_BLOCK_CNT 0x7E

	#define STDP4028_IRQ_OUT_CONF_REG 0x02
	#define STDP4028_DPTX_IRQ_EN_REG 0x3C
	#define STDP4028_DPTX_IRQ_STS_REG 0x3D
	#define STDP4028_DPTX_STS_REG 0x3E

	#define STDP4028_DPTX_DP_IRQ_EN 0x1000

	#define STDP4028_DPTX_HOTPLUG_IRQ_EN 0x0400
	#define STDP4028_DPTX_LINK_CH_IRQ_EN 0x2000
	#define STDP4028_DPTX_IRQ_CONFIG \
	(STDP4028_DPTX_LINK_CH_IRQ_EN \| STDP4028_DPTX_HOTPLUG_IRQ_EN)

	#define STDP4028_DPTX_HOTPLUG_STS 0x0200
	#define STDP4028_DPTX_LINK_STS 0x1000
	#define STDP4028_CON_STATE_CONNECTED \
	(STDP4028_DPTX_HOTPLUG_STS \| STDP4028_DPTX_LINK_STS)

	#define STDP4028_DPTX_HOTPLUG_CH_STS 0x0400
	#define STDP4028_DPTX_LINK_CH_STS 0x2000
	#define STDP4028_DPTX_IRQ_CLEAR \
	(STDP4028_DPTX_LINK_CH_STS \| STDP4028_DPTX_HOTPLUG_CH_STS)

	static DEFINE_MUTEX(ge_b850v3_lvds_dev_mutex);

	struct ge_b850v3_lvds {
	struct drm_connector connector;
	struct drm_bridge bridge;
	struct i2c_client *stdp4028_i2c;
	struct i2c_client *stdp2690_i2c;
	};

	static struct ge_b850v3_lvds *ge_b850v3_lvds_ptr;

	static int stdp2690_read_block(void context, u8 buf, unsigned int block, size_t len)
	{
	struct i2c_client *client = context;
	struct i2c_adapter *adapter = client->adapter;
	unsigned char start = block * EDID_LENGTH;

	struct i2c_msg msgs[] = {
	{
	.addr = client->addr,
	.flags = 0,
	.len = 1,
	.buf = &start,
	}, {
	.addr = client->addr,
	.flags = I2C_M_RD,
	.len = len,
	.buf = buf,
	}
	};

	if (i2c_transfer(adapter, msgs, 2) != 2)
	return -1;

	return 0;
	}

	static const struct drm_edid ge_b850v3_lvds_edid_read(struct drm_bridge bridge,
	struct drm_connector *connector)
	{
	struct i2c_client *client;

	client = ge_b850v3_lvds_ptr->stdp2690_i2c;

	return drm_edid_read_custom(connector, stdp2690_read_block, client);
	}

	static int ge_b850v3_lvds_get_modes(struct drm_connector *connector)
	{
	const struct drm_edid *drm_edid;
	int num_modes;

	drm_edid = ge_b850v3_lvds_edid_read(&ge_b850v3_lvds_ptr->bridge, connector);

	drm_edid_connector_update(connector, drm_edid);
	num_modes = drm_edid_connector_add_modes(connector);
	drm_edid_free(drm_edid);

	return num_modes;
	}

	static enum drm_mode_status ge_b850v3_lvds_mode_valid(
	struct drm_connector connector, struct drm_display_mode mode)
	{
	return MODE_OK;
	}

	static const struct
	drm_connector_helper_funcs ge_b850v3_lvds_connector_helper_funcs = {
	.get_modes = ge_b850v3_lvds_get_modes,
	.mode_valid = ge_b850v3_lvds_mode_valid,
	};

	static enum drm_connector_status ge_b850v3_lvds_bridge_detect(struct drm_bridge *bridge)
	{
	struct i2c_client *stdp4028_i2c =
	ge_b850v3_lvds_ptr->stdp4028_i2c;
	s32 link_state;

	link_state = i2c_smbus_read_word_data(stdp4028_i2c,
	STDP4028_DPTX_STS_REG);

	if (link_state == STDP4028_CON_STATE_CONNECTED)
	return connector_status_connected;

	if (link_state == 0)
	return connector_status_disconnected;

	return connector_status_unknown;
	}

	static enum drm_connector_status ge_b850v3_lvds_detect(struct drm_connector *connector,
	bool force)
	{
	return ge_b850v3_lvds_bridge_detect(&ge_b850v3_lvds_ptr->bridge);
	}

	static const struct drm_connector_funcs ge_b850v3_lvds_connector_funcs = {
	.fill_modes = drm_helper_probe_single_connector_modes,
	.detect = ge_b850v3_lvds_detect,
	.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 ge_b850v3_lvds_create_connector(struct drm_bridge *bridge)
	{
	struct drm_connector *connector = &ge_b850v3_lvds_ptr->connector;
	int ret;

	connector->polled = DRM_CONNECTOR_POLL_HPD;

	drm_connector_helper_add(connector,
	&ge_b850v3_lvds_connector_helper_funcs);

	ret = drm_connector_init(bridge->dev, connector,
	&ge_b850v3_lvds_connector_funcs,
	DRM_MODE_CONNECTOR_DisplayPort);
	if (ret) {
	DRM_ERROR("Failed to initialize connector with drm\n");
	return ret;
	}

	return drm_connector_attach_encoder(connector, bridge->encoder);
	}

	static irqreturn_t ge_b850v3_lvds_irq_handler(int irq, void *dev_id)
	{
	struct i2c_client *stdp4028_i2c
	= ge_b850v3_lvds_ptr->stdp4028_i2c;

	i2c_smbus_write_word_data(stdp4028_i2c,
	STDP4028_DPTX_IRQ_STS_REG,
	STDP4028_DPTX_IRQ_CLEAR);

	if (ge_b850v3_lvds_ptr->bridge.dev)
	drm_kms_helper_hotplug_event(ge_b850v3_lvds_ptr->bridge.dev);

	return IRQ_HANDLED;
	}

	static int ge_b850v3_lvds_attach(struct drm_bridge *bridge,
	enum drm_bridge_attach_flags flags)
	{
	struct i2c_client *stdp4028_i2c
	= ge_b850v3_lvds_ptr->stdp4028_i2c;

	/* Configures the bridge to re-enable interrupts after each ack. */
	i2c_smbus_write_word_data(stdp4028_i2c,
	STDP4028_IRQ_OUT_CONF_REG,
	STDP4028_DPTX_DP_IRQ_EN);

	/* Enable interrupts */
	i2c_smbus_write_word_data(stdp4028_i2c,
	STDP4028_DPTX_IRQ_EN_REG,
	STDP4028_DPTX_IRQ_CONFIG);

	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)
	return 0;

	return ge_b850v3_lvds_create_connector(bridge);
	}

	static const struct drm_bridge_funcs ge_b850v3_lvds_funcs = {
	.attach = ge_b850v3_lvds_attach,
	.detect = ge_b850v3_lvds_bridge_detect,
	.edid_read = ge_b850v3_lvds_edid_read,
	};

	static int ge_b850v3_lvds_init(struct device *dev)
	{
	mutex_lock(&ge_b850v3_lvds_dev_mutex);

	if (ge_b850v3_lvds_ptr)
	goto success;

	ge_b850v3_lvds_ptr = devm_kzalloc(dev,
	sizeof(*ge_b850v3_lvds_ptr),
	GFP_KERNEL);

	if (!ge_b850v3_lvds_ptr) {
	mutex_unlock(&ge_b850v3_lvds_dev_mutex);
	return -ENOMEM;
	}

	success:
	mutex_unlock(&ge_b850v3_lvds_dev_mutex);
	return 0;
	}

	static void ge_b850v3_lvds_remove(void)
	{
	mutex_lock(&ge_b850v3_lvds_dev_mutex);
	/*
	* This check is to avoid both the drivers
	* removing the bridge in their remove() function
	*/
	if (!ge_b850v3_lvds_ptr \|\|
	!ge_b850v3_lvds_ptr->stdp2690_i2c \|\|
	!ge_b850v3_lvds_ptr->stdp4028_i2c)
	goto out;

	drm_bridge_remove(&ge_b850v3_lvds_ptr->bridge);

	ge_b850v3_lvds_ptr = NULL;
	out:
	mutex_unlock(&ge_b850v3_lvds_dev_mutex);
	}

	static int ge_b850v3_register(void)
	{
	struct i2c_client *stdp4028_i2c = ge_b850v3_lvds_ptr->stdp4028_i2c;
	struct device *dev = &stdp4028_i2c->dev;

	/* drm bridge initialization */
	ge_b850v3_lvds_ptr->bridge.funcs = &ge_b850v3_lvds_funcs;
	ge_b850v3_lvds_ptr->bridge.ops = DRM_BRIDGE_OP_DETECT \|
	DRM_BRIDGE_OP_EDID;
	ge_b850v3_lvds_ptr->bridge.type = DRM_MODE_CONNECTOR_DisplayPort;
	ge_b850v3_lvds_ptr->bridge.of_node = dev->of_node;
	drm_bridge_add(&ge_b850v3_lvds_ptr->bridge);

	/* Clear pending interrupts since power up. */
	i2c_smbus_write_word_data(stdp4028_i2c,
	STDP4028_DPTX_IRQ_STS_REG,
	STDP4028_DPTX_IRQ_CLEAR);

	if (!stdp4028_i2c->irq)
	return 0;

	return devm_request_threaded_irq(&stdp4028_i2c->dev,
	stdp4028_i2c->irq, NULL,
	ge_b850v3_lvds_irq_handler,
	IRQF_TRIGGER_HIGH \| IRQF_ONESHOT,
	"ge-b850v3-lvds-dp", ge_b850v3_lvds_ptr);
	}

	static int stdp4028_ge_b850v3_fw_probe(struct i2c_client *stdp4028_i2c)
	{
	struct device *dev = &stdp4028_i2c->dev;
	int ret;

	ret = ge_b850v3_lvds_init(dev);

	if (ret)
	return ret;

	ge_b850v3_lvds_ptr->stdp4028_i2c = stdp4028_i2c;
	i2c_set_clientdata(stdp4028_i2c, ge_b850v3_lvds_ptr);

	/* Only register after both bridges are probed */
	if (!ge_b850v3_lvds_ptr->stdp2690_i2c)
	return 0;

	return ge_b850v3_register();
	}

	static void stdp4028_ge_b850v3_fw_remove(struct i2c_client *stdp4028_i2c)
	{
	ge_b850v3_lvds_remove();
	}

	static const struct i2c_device_id stdp4028_ge_b850v3_fw_i2c_table[] = {
	{"stdp4028_ge_fw", 0},
	{},
	};
	MODULE_DEVICE_TABLE(i2c, stdp4028_ge_b850v3_fw_i2c_table);

	static const struct of_device_id stdp4028_ge_b850v3_fw_match[] = {
	{ .compatible = "megachips,stdp4028-ge-b850v3-fw" },
	{},
	};
	MODULE_DEVICE_TABLE(of, stdp4028_ge_b850v3_fw_match);

	static struct i2c_driver stdp4028_ge_b850v3_fw_driver = {
	.id_table = stdp4028_ge_b850v3_fw_i2c_table,
	.probe = stdp4028_ge_b850v3_fw_probe,
	.remove = stdp4028_ge_b850v3_fw_remove,
	.driver = {
	.name = "stdp4028-ge-b850v3-fw",
	.of_match_table = stdp4028_ge_b850v3_fw_match,
	},
	};

	static int stdp2690_ge_b850v3_fw_probe(struct i2c_client *stdp2690_i2c)
	{
	struct device *dev = &stdp2690_i2c->dev;
	int ret;

	ret = ge_b850v3_lvds_init(dev);

	if (ret)
	return ret;

	ge_b850v3_lvds_ptr->stdp2690_i2c = stdp2690_i2c;
	i2c_set_clientdata(stdp2690_i2c, ge_b850v3_lvds_ptr);

	/* Only register after both bridges are probed */
	if (!ge_b850v3_lvds_ptr->stdp4028_i2c)
	return 0;

	return ge_b850v3_register();
	}

	static void stdp2690_ge_b850v3_fw_remove(struct i2c_client *stdp2690_i2c)
	{
	ge_b850v3_lvds_remove();
	}

	static const struct i2c_device_id stdp2690_ge_b850v3_fw_i2c_table[] = {
	{"stdp2690_ge_fw", 0},
	{},
	};
	MODULE_DEVICE_TABLE(i2c, stdp2690_ge_b850v3_fw_i2c_table);

	static const struct of_device_id stdp2690_ge_b850v3_fw_match[] = {
	{ .compatible = "megachips,stdp2690-ge-b850v3-fw" },
	{},
	};
	MODULE_DEVICE_TABLE(of, stdp2690_ge_b850v3_fw_match);

	static struct i2c_driver stdp2690_ge_b850v3_fw_driver = {
	.id_table = stdp2690_ge_b850v3_fw_i2c_table,
	.probe = stdp2690_ge_b850v3_fw_probe,
	.remove = stdp2690_ge_b850v3_fw_remove,
	.driver = {
	.name = "stdp2690-ge-b850v3-fw",
	.of_match_table = stdp2690_ge_b850v3_fw_match,
	},
	};

	static int __init stdpxxxx_ge_b850v3_init(void)
	{
	int ret;

	ret = i2c_add_driver(&stdp4028_ge_b850v3_fw_driver);
	if (ret)
	return ret;

	ret = i2c_add_driver(&stdp2690_ge_b850v3_fw_driver);
	if (ret)
	i2c_del_driver(&stdp4028_ge_b850v3_fw_driver);

	return ret;
	}
	module_init(stdpxxxx_ge_b850v3_init);

	static void __exit stdpxxxx_ge_b850v3_exit(void)
	{
	i2c_del_driver(&stdp2690_ge_b850v3_fw_driver);
	i2c_del_driver(&stdp4028_ge_b850v3_fw_driver);
	}
	module_exit(stdpxxxx_ge_b850v3_exit);

	MODULE_AUTHOR("Peter Senna Tschudin <peter.senna@collabora.com>");
	MODULE_AUTHOR("Martyn Welch <martyn.welch@collabora.co.uk>");
	MODULE_DESCRIPTION("GE LVDS to DP++ display bridge)");
	MODULE_LICENSE("GPL v2");