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#include 

 * 0 on success, -ERRNO on failure.

 *

 * IMPORTANT:

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

/**

 * 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);