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/*

 * Copyright © 2009 Keith Packard

 *

 * Permission to use, copy, modify, distribute, and sell this software and its

 * documentation for any purpose is hereby granted without fee, provided that

 * the above copyright notice appear in all copies and that both that copyright

 * notice and this permission notice appear in supporting documentation, and

 * that the name of the copyright holders not be used in advertising or

 * publicity pertaining to distribution of the software without specific,

 * written prior permission.  The copyright holders make no representations

 * about the suitability of this software for any purpose.  It is provided "as

 * is" without express or implied warranty.

 *

 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,

 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO

 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR

 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,

 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER

 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE

 * OF THIS SOFTWARE.

 */

#include 

#include 

//#include 

//#include 

#include 

#include 

#include 

#include 

#include 

/**

 * DOC: dp helpers

 *

 * These functions contain some common logic and helpers at various abstraction

 * levels to deal with Display Port sink devices and related things like DP aux

 * channel transfers, EDID reading over DP aux channels, decoding certain DPCD

 * blocks, ...

 */

/* Run a single AUX_CH I2C transaction, writing/reading data as necessary */

static int

i2c_algo_dp_aux_transaction(struct i2c_adapter *adapter, int mode,

			    uint8_t write_byte, uint8_t *read_byte)

{

	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;

	int ret;

	ret = (*algo_data->aux_ch)(adapter, mode,

				   write_byte, read_byte);

	return ret;

}

/*

 * I2C over AUX CH

 */

/*

 * Send the address. If the I2C link is running, this 'restarts'

 * the connection with the new address, this is used for doing

 * a write followed by a read (as needed for DDC)

 */

static int

i2c_algo_dp_aux_address(struct i2c_adapter *adapter, u16 address, bool reading)

{

	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;

	int mode = MODE_I2C_START;

	int ret;

	if (reading)

		mode |= MODE_I2C_READ;

	else

		mode |= MODE_I2C_WRITE;

	algo_data->address = address;

	algo_data->running = true;

	ret = i2c_algo_dp_aux_transaction(adapter, mode, 0, NULL);

	return ret;

}

/*

 * Stop the I2C transaction. This closes out the link, sending

 * a bare address packet with the MOT bit turned off

 */

static void

i2c_algo_dp_aux_stop(struct i2c_adapter *adapter, bool reading)

{

	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;

	int mode = MODE_I2C_STOP;

	if (reading)

		mode |= MODE_I2C_READ;

	else

		mode |= MODE_I2C_WRITE;

	if (algo_data->running) {

		(void) i2c_algo_dp_aux_transaction(adapter, mode, 0, NULL);

		algo_data->running = false;

	}

}

/*

 * Write a single byte to the current I2C address, the

 * the I2C link must be running or this returns -EIO

 */

static int

i2c_algo_dp_aux_put_byte(struct i2c_adapter *adapter, u8 byte)

{

	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;

	int ret;

	if (!algo_data->running)

		return -EIO;

	ret = i2c_algo_dp_aux_transaction(adapter, MODE_I2C_WRITE, byte, NULL);

	return ret;

}

/*

 * Read a single byte from the current I2C address, the

 * I2C link must be running or this returns -EIO

 */

static int

i2c_algo_dp_aux_get_byte(struct i2c_adapter *adapter, u8 *byte_ret)

{

	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;

	int ret;

	if (!algo_data->running)

		return -EIO;

	ret = i2c_algo_dp_aux_transaction(adapter, MODE_I2C_READ, 0, byte_ret);

	return ret;

}

static int

i2c_algo_dp_aux_xfer(struct i2c_adapter *adapter,

		     struct i2c_msg *msgs,

		     int num)

{

	int ret = 0;

	bool reading = false;

	int m;

	int b;

	for (m = 0; m < num; m++) {

		u16 len = msgs[m].len;

		u8 *buf = msgs[m].buf;

		reading = (msgs[m].flags & I2C_M_RD) != 0;

		ret = i2c_algo_dp_aux_address(adapter, msgs[m].addr, reading);

		if (ret < 0)

			break;

		if (reading) {

			for (b = 0; b < len; b++) {

				ret = i2c_algo_dp_aux_get_byte(adapter, &buf[b]);

				if (ret < 0)

					break;

			}

		} else {

			for (b = 0; b < len; b++) {

				ret = i2c_algo_dp_aux_put_byte(adapter, buf[b]);

				if (ret < 0)

					break;

			}

		}

		if (ret < 0)

			break;

	}

	if (ret >= 0)

		ret = num;

	i2c_algo_dp_aux_stop(adapter, reading);

	DRM_DEBUG_KMS("dp_aux_xfer return %d\n", ret);

	return ret;

}

static u32

i2c_algo_dp_aux_functionality(struct i2c_adapter *adapter)

{

	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |

	       I2C_FUNC_SMBUS_READ_BLOCK_DATA |

	       I2C_FUNC_SMBUS_BLOCK_PROC_CALL |

	       I2C_FUNC_10BIT_ADDR;

}

static const struct i2c_algorithm i2c_dp_aux_algo = {

	.master_xfer	= i2c_algo_dp_aux_xfer,

	.functionality	= i2c_algo_dp_aux_functionality,

};

static void

i2c_dp_aux_reset_bus(struct i2c_adapter *adapter)

{

	(void) i2c_algo_dp_aux_address(adapter, 0, false);

	(void) i2c_algo_dp_aux_stop(adapter, false);

}

static int

i2c_dp_aux_prepare_bus(struct i2c_adapter *adapter)

{

	adapter->algo = &i2c_dp_aux_algo;

	adapter->retries = 3;

	i2c_dp_aux_reset_bus(adapter);

	return 0;

}

/**

 * i2c_dp_aux_add_bus() - register an i2c adapter using the aux ch helper

 * @adapter: i2c adapter to register

 *

 * This registers an i2c adapter that uses dp aux channel as it's underlaying

 * transport. The driver needs to fill out the &i2c_algo_dp_aux_data structure

 * and store it in the algo_data member of the @adapter argument. This will be

 * used by the i2c over dp aux algorithm to drive the hardware.

 *

 * RETURNS:

 * 0 on success, -ERRNO on failure.

 *

 * IMPORTANT:

 * This interface is deprecated, please switch to the new dp aux helpers and

 * drm_dp_aux_register().

 */

int

i2c_dp_aux_add_bus(struct i2c_adapter *adapter)

{

	int error;

	error = i2c_dp_aux_prepare_bus(adapter);

	if (error)

		return error;

	error = i2c_add_adapter(adapter);

	return error;

}

EXPORT_SYMBOL(i2c_dp_aux_add_bus);

/* Helpers for DP link training */

static u8 dp_link_status(const u8 link_status[DP_LINK_STATUS_SIZE], int r)

{

	return link_status[r - DP_LANE0_1_STATUS];

}

static u8 dp_get_lane_status(const u8 link_status[DP_LINK_STATUS_SIZE],

			     int lane)

{

	int i = DP_LANE0_1_STATUS + (lane >> 1);

	int s = (lane & 1) * 4;

	u8 l = dp_link_status(link_status, i);

	return (l >> s) & 0xf;

}

bool drm_dp_channel_eq_ok(const u8 link_status[DP_LINK_STATUS_SIZE],

			  int lane_count)

{

	u8 lane_align;

	u8 lane_status;

	int lane;

	lane_align = dp_link_status(link_status,

				    DP_LANE_ALIGN_STATUS_UPDATED);

	if ((lane_align & DP_INTERLANE_ALIGN_DONE) == 0)

		return false;

	for (lane = 0; lane < lane_count; lane++) {

		lane_status = dp_get_lane_status(link_status, lane);

		if ((lane_status & DP_CHANNEL_EQ_BITS) != DP_CHANNEL_EQ_BITS)

			return false;

	}

	return true;

}

EXPORT_SYMBOL(drm_dp_channel_eq_ok);

bool drm_dp_clock_recovery_ok(const u8 link_status[DP_LINK_STATUS_SIZE],

			      int lane_count)

{

	int lane;

	u8 lane_status;

	for (lane = 0; lane < lane_count; lane++) {

		lane_status = dp_get_lane_status(link_status, lane);

		if ((lane_status & DP_LANE_CR_DONE) == 0)

			return false;

	}

	return true;

}

EXPORT_SYMBOL(drm_dp_clock_recovery_ok);

u8 drm_dp_get_adjust_request_voltage(const u8 link_status[DP_LINK_STATUS_SIZE],

				     int lane)

{

	int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1);

	int s = ((lane & 1) ?

		 DP_ADJUST_VOLTAGE_SWING_LANE1_SHIFT :

		 DP_ADJUST_VOLTAGE_SWING_LANE0_SHIFT);

	u8 l = dp_link_status(link_status, i);

	return ((l >> s) & 0x3) << DP_TRAIN_VOLTAGE_SWING_SHIFT;

}

EXPORT_SYMBOL(drm_dp_get_adjust_request_voltage);

u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SIZE],

					  int lane)

{

	int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1);

	int s = ((lane & 1) ?

		 DP_ADJUST_PRE_EMPHASIS_LANE1_SHIFT :

		 DP_ADJUST_PRE_EMPHASIS_LANE0_SHIFT);

	u8 l = dp_link_status(link_status, i);

	return ((l >> s) & 0x3) << DP_TRAIN_PRE_EMPHASIS_SHIFT;

}

EXPORT_SYMBOL(drm_dp_get_adjust_request_pre_emphasis);

void drm_dp_link_train_clock_recovery_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) {

	if (dpcd[DP_TRAINING_AUX_RD_INTERVAL] == 0)

		udelay(100);

	else

		mdelay(dpcd[DP_TRAINING_AUX_RD_INTERVAL] * 4);

}

EXPORT_SYMBOL(drm_dp_link_train_clock_recovery_delay);

void drm_dp_link_train_channel_eq_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) {

	if (dpcd[DP_TRAINING_AUX_RD_INTERVAL] == 0)

		udelay(400);

	else

		mdelay(dpcd[DP_TRAINING_AUX_RD_INTERVAL] * 4);

}

EXPORT_SYMBOL(drm_dp_link_train_channel_eq_delay);

u8 drm_dp_link_rate_to_bw_code(int link_rate)

{

	switch (link_rate) {

	case 162000:

	default:

		return DP_LINK_BW_1_62;

	case 270000:

		return DP_LINK_BW_2_7;

	case 540000:

		return DP_LINK_BW_5_4;

	}

}

EXPORT_SYMBOL(drm_dp_link_rate_to_bw_code);

int drm_dp_bw_code_to_link_rate(u8 link_bw)

{

	switch (link_bw) {

	case DP_LINK_BW_1_62:

	default:

		return 162000;

	case DP_LINK_BW_2_7:

		return 270000;

	case DP_LINK_BW_5_4:

		return 540000;

	}

}

EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate);

/**

 * DOC: dp helpers

 *

 * The DisplayPort AUX channel is an abstraction to allow generic, driver-

 * independent access to AUX functionality. Drivers can take advantage of

 * this by filling in the fields of the drm_dp_aux structure.

 *

 * Transactions are described using a hardware-independent drm_dp_aux_msg

 * structure, which is passed into a driver's .transfer() implementation.

 * Both native and I2C-over-AUX transactions are supported.

 */

static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,

			      unsigned int offset, void *buffer, size_t size)

{

	struct drm_dp_aux_msg msg;

	unsigned int retry;

	int err;

	memset(&msg, 0, sizeof(msg));

	msg.address = offset;

	msg.request = request;

	msg.buffer = buffer;

	msg.size = size;

	/*

	 * The specification doesn't give any recommendation on how often to

	 * retry native transactions, so retry 7 times like for I2C-over-AUX

	 * transactions.

	 */

	for (retry = 0; retry < 7; retry++) {

		mutex_lock(&aux->hw_mutex);

		err = aux->transfer(aux, &msg);

		mutex_unlock(&aux->hw_mutex);

		if (err < 0) {

			if (err == -EBUSY)

				continue;

			return err;

		}

		switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) {

		case DP_AUX_NATIVE_REPLY_ACK:

			if (err < size)

				return -EPROTO;

			return err;

		case DP_AUX_NATIVE_REPLY_NACK:

			return -EIO;

		case DP_AUX_NATIVE_REPLY_DEFER:

			usleep(500);

			break;

		}

	}

	DRM_DEBUG_KMS("too many retries, giving up\n");

	return -EIO;

}

/**

 * drm_dp_dpcd_read() - read a series of bytes from the DPCD

 * @aux: DisplayPort AUX channel

 * @offset: address of the (first) register to read

 * @buffer: buffer to store the register values

 * @size: number of bytes in @buffer

 *

 * Returns the number of bytes transferred on success, or a negative error

 * code on failure. -EIO is returned if the request was NAKed by the sink or

 * if the retry count was exceeded. If not all bytes were transferred, this

 * function returns -EPROTO. Errors from the underlying AUX channel transfer

 * function, with the exception of -EBUSY (which causes the transaction to

 * be retried), are propagated to the caller.

 */

ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,

			 void *buffer, size_t size)

{

	return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, buffer,

				  size);

}

EXPORT_SYMBOL(drm_dp_dpcd_read);

/**

 * drm_dp_dpcd_write() - write a series of bytes to the DPCD

 * @aux: DisplayPort AUX channel

 * @offset: address of the (first) register to write

 * @buffer: buffer containing the values to write

 * @size: number of bytes in @buffer

 *

 * Returns the number of bytes transferred on success, or a negative error

 * code on failure. -EIO is returned if the request was NAKed by the sink or

 * if the retry count was exceeded. If not all bytes were transferred, this

 * function returns -EPROTO. Errors from the underlying AUX channel transfer

 * function, with the exception of -EBUSY (which causes the transaction to

 * be retried), are propagated to the caller.

 */

ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset,

			  void *buffer, size_t size)

{

	return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_WRITE, offset, buffer,

				  size);

}

EXPORT_SYMBOL(drm_dp_dpcd_write);

/**

 * drm_dp_dpcd_read_link_status() - read DPCD link status (bytes 0x202-0x207)

 * @aux: DisplayPort AUX channel

 * @status: buffer to store the link status in (must be at least 6 bytes)

 *

 * Returns the number of bytes transferred on success or a negative error

 * code on failure.

 */

int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,

				 u8 status[DP_LINK_STATUS_SIZE])

{

	return drm_dp_dpcd_read(aux, DP_LANE0_1_STATUS, status,

				DP_LINK_STATUS_SIZE);

}

EXPORT_SYMBOL(drm_dp_dpcd_read_link_status);

/**

 * drm_dp_link_probe() - probe a DisplayPort link for capabilities

 * @aux: DisplayPort AUX channel

 * @link: pointer to structure in which to return link capabilities

 *

 * The structure filled in by this function can usually be passed directly

 * into drm_dp_link_power_up() and drm_dp_link_configure() to power up and

 * configure the link based on the link's capabilities.

 *

 * Returns 0 on success or a negative error code on failure.

 */

int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link)

{

	u8 values[3];

	int err;

	memset(link, 0, sizeof(*link));

	err = drm_dp_dpcd_read(aux, DP_DPCD_REV, values, sizeof(values));

	if (err < 0)

		return err;

	link->revision = values[0];

	link->rate = drm_dp_bw_code_to_link_rate(values[1]);

	link->num_lanes = values[2] & DP_MAX_LANE_COUNT_MASK;

	if (values[2] & DP_ENHANCED_FRAME_CAP)

		link->capabilities |= DP_LINK_CAP_ENHANCED_FRAMING;

	return 0;

}

EXPORT_SYMBOL(drm_dp_link_probe);

/**

 * drm_dp_link_power_up() - power up a DisplayPort link

 * @aux: DisplayPort AUX channel

 * @link: pointer to a structure containing the link configuration

 *

 * Returns 0 on success or a negative error code on failure.

 */

int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link)

{

	u8 value;

	int err;

	/* DP_SET_POWER register is only available on DPCD v1.1 and later */

	if (link->revision < 0x11)

		return 0;

	err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value);

	if (err < 0)

		return err;

	value &= ~DP_SET_POWER_MASK;

	value |= DP_SET_POWER_D0;

	err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);

	if (err < 0)

		return err;

	/*

	 * According to the DP 1.1 specification, a "Sink Device must exit the

	 * power saving state within 1 ms" (Section 2.5.3.1, Table 5-52, "Sink

	 * Control Field" (register 0x600).

	 */

	usleep(2000);

	return 0;

}

EXPORT_SYMBOL(drm_dp_link_power_up);

/**

 * drm_dp_link_configure() - configure a DisplayPort link

 * @aux: DisplayPort AUX channel

 * @link: pointer to a structure containing the link configuration

 *

 * Returns 0 on success or a negative error code on failure.

 */

int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link)

{

	u8 values[2];

	int err;

	values[0] = drm_dp_link_rate_to_bw_code(link->rate);

	values[1] = link->num_lanes;

	if (link->capabilities & DP_LINK_CAP_ENHANCED_FRAMING)

		values[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN;

	err = drm_dp_dpcd_write(aux, DP_LINK_BW_SET, values, sizeof(values));

	if (err < 0)

		return err;

	return 0;

}

EXPORT_SYMBOL(drm_dp_link_configure);

/*

 * I2C-over-AUX implementation

 */

static u32 drm_dp_i2c_functionality(struct i2c_adapter *adapter)

{

	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |

	       I2C_FUNC_SMBUS_READ_BLOCK_DATA |

	       I2C_FUNC_SMBUS_BLOCK_PROC_CALL |

	       I2C_FUNC_10BIT_ADDR;

}

/*

 * Transfer a single I2C-over-AUX message and handle various error conditions,

 * retrying the transaction as appropriate.  It is assumed that the

 * aux->transfer function does not modify anything in the msg other than the

 * reply field.

 */

static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)

{

	unsigned int retry;

	int err;

	/*

	 * DP1.2 sections 2.7.7.1.5.6.1 and 2.7.7.1.6.6.1: A DP Source device

	 * is required to retry at least seven times upon receiving AUX_DEFER

	 * before giving up the AUX transaction.

	 */

	for (retry = 0; retry < 7; retry++) {

		mutex_lock(&aux->hw_mutex);

		err = aux->transfer(aux, msg);

		mutex_unlock(&aux->hw_mutex);

		if (err < 0) {

			if (err == -EBUSY)

				continue;

			DRM_DEBUG_KMS("transaction failed: %d\n", err);

			return err;

		}

		switch (msg->reply & DP_AUX_NATIVE_REPLY_MASK) {

		case DP_AUX_NATIVE_REPLY_ACK:

			/*

			 * For I2C-over-AUX transactions this isn't enough, we

			 * need to check for the I2C ACK reply.

			 */

			break;

		case DP_AUX_NATIVE_REPLY_NACK:

			DRM_DEBUG_KMS("native nack\n");

			return -EREMOTEIO;

		case DP_AUX_NATIVE_REPLY_DEFER:

			DRM_DEBUG_KMS("native defer");

			/*

			 * We could check for I2C bit rate capabilities and if

			 * available adjust this interval. We could also be

			 * more careful with DP-to-legacy adapters where a

			 * long legacy cable may force very low I2C bit rates.

			 *

			 * For now just defer for long enough to hopefully be

			 * safe for all use-cases.

			 */

			usleep_range(500, 600);

			continue;

		default:

			DRM_ERROR("invalid native reply %#04x\n", msg->reply);

			return -EREMOTEIO;

		}

		switch (msg->reply & DP_AUX_I2C_REPLY_MASK) {

		case DP_AUX_I2C_REPLY_ACK:

			/*

			 * Both native ACK and I2C ACK replies received. We

			 * can assume the transfer was successful.

			 */

			if (err < msg->size)

				return -EPROTO;

			return 0;

		case DP_AUX_I2C_REPLY_NACK:

			DRM_DEBUG_KMS("I2C nack\n");

			return -EREMOTEIO;

		case DP_AUX_I2C_REPLY_DEFER:

			DRM_DEBUG_KMS("I2C defer\n");

			usleep_range(400, 500);

			continue;

		default:

			DRM_ERROR("invalid I2C reply %#04x\n", msg->reply);

			return -EREMOTEIO;

		}

	}

	DRM_DEBUG_KMS("too many retries, giving up\n");

	return -EREMOTEIO;

}

static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,

			   int num)

{

	struct drm_dp_aux *aux = adapter->algo_data;

	unsigned int i, j;

	struct drm_dp_aux_msg msg;

	int err = 0;

	memset(&msg, 0, sizeof(msg));

	for (i = 0; i < num; i++) {

		msg.address = msgs[i].addr;

		msg.request = (msgs[i].flags & I2C_M_RD) ?

			DP_AUX_I2C_READ :

			DP_AUX_I2C_WRITE;

		msg.request |= DP_AUX_I2C_MOT;

		/* Send a bare address packet to start the transaction.

		 * Zero sized messages specify an address only (bare

		 * address) transaction.

		 */

		msg.buffer = NULL;

		msg.size = 0;

		err = drm_dp_i2c_do_msg(aux, &msg);

		if (err < 0)

			break;

		/*

		 * Many hardware implementations support FIFOs larger than a

		 * single byte, but it has been empirically determined that

		 * transferring data in larger chunks can actually lead to

		 * decreased performance. Therefore each message is simply

		 * transferred byte-by-byte.

		 */

		for (j = 0; j < msgs[i].len; j++) {

			msg.buffer = msgs[i].buf + j;

			msg.size = 1;

			err = drm_dp_i2c_do_msg(aux, &msg);

			if (err < 0)

				break;

		}

		if (err < 0)

			break;

	}

	if (err >= 0)

		err = num;

	/* Send a bare address packet to close out the transaction.

	 * Zero sized messages specify an address only (bare

	 * address) transaction.

	 */

	msg.request &= ~DP_AUX_I2C_MOT;

	msg.buffer = NULL;

	msg.size = 0;

	(void)drm_dp_i2c_do_msg(aux, &msg);

	return err;

}

static const struct i2c_algorithm drm_dp_i2c_algo = {

	.functionality = drm_dp_i2c_functionality,

	.master_xfer = drm_dp_i2c_xfer,

};

/**

 * drm_dp_aux_register() - initialise and register aux channel

 * @aux: DisplayPort AUX channel

 *

 * Returns 0 on success or a negative error code on failure.

 */

int drm_dp_aux_register(struct drm_dp_aux *aux)

{

	mutex_init(&aux->hw_mutex);

	aux->ddc.algo = &drm_dp_i2c_algo;

	aux->ddc.algo_data = aux;

	aux->ddc.retries = 3;

	aux->ddc.class = I2C_CLASS_DDC;

	aux->ddc.owner = THIS_MODULE;

	aux->ddc.dev.parent = aux->dev;

//	aux->ddc.dev.of_node = aux->dev->of_node;

    strlcpy(aux->ddc.name, aux->name ? aux->name : "aux",

		sizeof(aux->ddc.name));

	return i2c_add_adapter(&aux->ddc);

}

EXPORT_SYMBOL(drm_dp_aux_register);

/**

 * drm_dp_aux_unregister() - unregister an AUX adapter

 * @aux: DisplayPort AUX channel

 */

void drm_dp_aux_unregister(struct drm_dp_aux *aux)

{

	i2c_del_adapter(&aux->ddc);

}

EXPORT_SYMBOL(drm_dp_aux_unregister);