drivers/gpu/drm/msm/dp/dp_aux.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (c) 2012-2020, The Linux Foundation. All rights reserved.
  */

 #include <linux/delay.h>
 #include <linux/phy/phy.h>
 #include <drm/drm_print.h>

 #include "dp_reg.h"
 #include "dp_aux.h"

 enum msm_dp_aux_err {
 	DP_AUX_ERR_NONE,
 	DP_AUX_ERR_ADDR,
 	DP_AUX_ERR_TOUT,
 	DP_AUX_ERR_NACK,
 	DP_AUX_ERR_DEFER,
 	DP_AUX_ERR_NACK_DEFER,
 	DP_AUX_ERR_PHY,
 };

 struct dp_aux_private {
 	struct device *dev;
 	struct dp_catalog *catalog;

 	struct phy *phy;

 	struct mutex mutex;
 	struct completion comp;

 	enum msm_dp_aux_err aux_error_num;
 	u32 retry_cnt;
 	bool cmd_busy;
 	bool native;
 	bool read;
 	bool no_send_addr;
 	bool no_send_stop;
 	bool initted;
 	bool is_edp;
 	bool enable_xfers;
 	u32 offset;
 	u32 segment;

 	struct drm_dp_aux dp_aux;
 };

 #define MAX_AUX_RETRIES			5

 static ssize_t dp_aux_write(struct dp_aux_private *aux,
 			struct drm_dp_aux_msg *msg)
 {
 	u8 data[4];
 	u32 reg;
 	ssize_t len;
 	u8 *msgdata = msg->buffer;
 	int const AUX_CMD_FIFO_LEN = 128;
 	int i = 0;

 	if (aux->read)
 		len = 0;
 	else
 		len = msg->size;

 	/*
 	 * cmd fifo only has depth of 144 bytes
 	 * limit buf length to 128 bytes here
 	 */
 	if (len > AUX_CMD_FIFO_LEN - 4) {
 		DRM_ERROR("buf size greater than allowed size of 128 bytes\n");
 		return -EINVAL;
 	}

 	/* Pack cmd and write to HW */
 	data[0] = (msg->address >> 16) & 0xf;	/* addr[19:16] */
 	if (aux->read)
 		data[0] |=  BIT(4);		/* R/W */

 	data[1] = msg->address >> 8;		/* addr[15:8] */
 	data[2] = msg->address;			/* addr[7:0] */
 	data[3] = msg->size - 1;		/* len[7:0] */

 	for (i = 0; i < len + 4; i++) {
 		reg = (i < 4) ? data[i] : msgdata[i - 4];
 		reg <<= DP_AUX_DATA_OFFSET;
 		reg &= DP_AUX_DATA_MASK;
 		reg |= DP_AUX_DATA_WRITE;
 		/* index = 0, write */
 		if (i == 0)
 			reg |= DP_AUX_DATA_INDEX_WRITE;
 		dp_catalog_aux_write_data(aux->catalog, reg);
 	}

 	dp_catalog_aux_clear_trans(aux->catalog, false);
 	dp_catalog_aux_clear_hw_interrupts(aux->catalog);

 	reg = 0; /* Transaction number == 1 */
 	if (!aux->native) { /* i2c */
 		reg |= DP_AUX_TRANS_CTRL_I2C;

 		if (aux->no_send_addr)
 			reg |= DP_AUX_TRANS_CTRL_NO_SEND_ADDR;

 		if (aux->no_send_stop)
 			reg |= DP_AUX_TRANS_CTRL_NO_SEND_STOP;
 	}

 	reg |= DP_AUX_TRANS_CTRL_GO;
 	dp_catalog_aux_write_trans(aux->catalog, reg);

 	return len;
 }

 static ssize_t dp_aux_cmd_fifo_tx(struct dp_aux_private *aux,
 			      struct drm_dp_aux_msg *msg)
 {
 	ssize_t ret;
 	unsigned long time_left;

 	reinit_completion(&aux->comp);

 	ret = dp_aux_write(aux, msg);
 	if (ret < 0)
 		return ret;

 	time_left = wait_for_completion_timeout(&aux->comp,
 						msecs_to_jiffies(250));
 	if (!time_left)
 		return -ETIMEDOUT;

 	return ret;
 }

 static ssize_t dp_aux_cmd_fifo_rx(struct dp_aux_private *aux,
 		struct drm_dp_aux_msg *msg)
 {
 	u32 data;
 	u8 *dp;
 	u32 i, actual_i;
 	u32 len = msg->size;

 	dp_catalog_aux_clear_trans(aux->catalog, true);

 	data = DP_AUX_DATA_INDEX_WRITE; /* INDEX_WRITE */
 	data |= DP_AUX_DATA_READ;  /* read */

 	dp_catalog_aux_write_data(aux->catalog, data);

 	dp = msg->buffer;

 	/* discard first byte */
 	data = dp_catalog_aux_read_data(aux->catalog);

 	for (i = 0; i < len; i++) {
 		data = dp_catalog_aux_read_data(aux->catalog);
 		*dp++ = (u8)((data >> DP_AUX_DATA_OFFSET) & 0xff);

 		actual_i = (data >> DP_AUX_DATA_INDEX_OFFSET) & 0xFF;
 		if (i != actual_i)
 			break;
 	}

 	return i;
 }

 static void dp_aux_update_offset_and_segment(struct dp_aux_private *aux,
 					     struct drm_dp_aux_msg *input_msg)
 {
 	u32 edid_address = 0x50;
 	u32 segment_address = 0x30;
 	bool i2c_read = input_msg->request &
 		(DP_AUX_I2C_READ & DP_AUX_NATIVE_READ);
 	u8 *data;

 	if (aux->native || i2c_read || ((input_msg->address != edid_address) &&
 		(input_msg->address != segment_address)))
 		return;


 	data = input_msg->buffer;
 	if (input_msg->address == segment_address)
 		aux->segment = *data;
 	else
 		aux->offset = *data;
 }

 /**
  * dp_aux_transfer_helper() - helper function for EDID read transactions
  *
  * @aux: DP AUX private structure
  * @input_msg: input message from DRM upstream APIs
  * @send_seg: send the segment to sink
  *
  * return: void
  *
  * This helper function is used to fix EDID reads for non-compliant
  * sinks that do not handle the i2c middle-of-transaction flag correctly.
  */
 static void dp_aux_transfer_helper(struct dp_aux_private *aux,
 				   struct drm_dp_aux_msg *input_msg,
 				   bool send_seg)
 {
 	struct drm_dp_aux_msg helper_msg;
 	u32 message_size = 0x10;
 	u32 segment_address = 0x30;
 	u32 const edid_block_length = 0x80;
 	bool i2c_mot = input_msg->request & DP_AUX_I2C_MOT;
 	bool i2c_read = input_msg->request &
 		(DP_AUX_I2C_READ & DP_AUX_NATIVE_READ);

 	if (!i2c_mot || !i2c_read || (input_msg->size == 0))
 		return;

 	/*
 	 * Sending the segment value and EDID offset will be performed
 	 * from the DRM upstream EDID driver for each block. Avoid
 	 * duplicate AUX transactions related to this while reading the
 	 * first 16 bytes of each block.
 	 */
 	if (!(aux->offset % edid_block_length) || !send_seg)
 		goto end;

 	aux->read = false;
 	aux->cmd_busy = true;
 	aux->no_send_addr = true;
 	aux->no_send_stop = true;

 	/*
 	 * Send the segment address for every i2c read in which the
 	 * middle-of-tranaction flag is set. This is required to support EDID
 	 * reads of more than 2 blocks as the segment address is reset to 0
 	 * since we are overriding the middle-of-transaction flag for read
 	 * transactions.
 	 */

 	if (aux->segment) {
 		memset(&helper_msg, 0, sizeof(helper_msg));
 		helper_msg.address = segment_address;
 		helper_msg.buffer = &aux->segment;
 		helper_msg.size = 1;
 		dp_aux_cmd_fifo_tx(aux, &helper_msg);
 	}

 	/*
 	 * Send the offset address for every i2c read in which the
 	 * middle-of-transaction flag is set. This will ensure that the sink
 	 * will update its read pointer and return the correct portion of the
 	 * EDID buffer in the subsequent i2c read trasntion triggered in the
 	 * native AUX transfer function.
 	 */
 	memset(&helper_msg, 0, sizeof(helper_msg));
 	helper_msg.address = input_msg->address;
 	helper_msg.buffer = &aux->offset;
 	helper_msg.size = 1;
 	dp_aux_cmd_fifo_tx(aux, &helper_msg);

 end:
 	aux->offset += message_size;
 	if (aux->offset == 0x80 || aux->offset == 0x100)
 		aux->segment = 0x0; /* reset segment at end of block */
 }

 /*
  * This function does the real job to process an AUX transaction.
  * It will call aux_reset() function to reset the AUX channel,
  * if the waiting is timeout.
  */
 static ssize_t dp_aux_transfer(struct drm_dp_aux *dp_aux,
 			       struct drm_dp_aux_msg *msg)
 {
 	ssize_t ret;
 	int const aux_cmd_native_max = 16;
 	int const aux_cmd_i2c_max = 128;
 	struct dp_aux_private *aux;

 	aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

 	aux->native = msg->request & (DP_AUX_NATIVE_WRITE & DP_AUX_NATIVE_READ);

 	/* Ignore address only message */
 	if (msg->size == 0 || !msg->buffer) {
 		msg->reply = aux->native ?
 			DP_AUX_NATIVE_REPLY_ACK : DP_AUX_I2C_REPLY_ACK;
 		return msg->size;
 	}

 	/* msg sanity check */
 	if ((aux->native && msg->size > aux_cmd_native_max) ||
 	    msg->size > aux_cmd_i2c_max) {
 		DRM_ERROR("%s: invalid msg: size(%zu), request(%x)\n",
 			__func__, msg->size, msg->request);
 		return -EINVAL;
 	}

 	ret = pm_runtime_resume_and_get(dp_aux->dev);
 	if (ret)
 		return  ret;

 	mutex_lock(&aux->mutex);
 	if (!aux->initted) {
 		ret = -EIO;
 		goto exit;
 	}

 	/*
 	 * If we're using DP and an external display isn't connected then the
 	 * transfer won't succeed. Return right away. If we don't do this we
 	 * can end up with long timeouts if someone tries to access the DP AUX
 	 * character device when no DP device is connected.
 	 */
 	if (!aux->is_edp && !aux->enable_xfers) {
 		ret = -ENXIO;
 		goto exit;
 	}

 	dp_aux_update_offset_and_segment(aux, msg);
 	dp_aux_transfer_helper(aux, msg, true);

 	aux->read = msg->request & (DP_AUX_I2C_READ & DP_AUX_NATIVE_READ);
 	aux->cmd_busy = true;

 	if (aux->read) {
 		aux->no_send_addr = true;
 		aux->no_send_stop = false;
 	} else {
 		aux->no_send_addr = true;
 		aux->no_send_stop = true;
 	}

 	ret = dp_aux_cmd_fifo_tx(aux, msg);
 	if (ret < 0) {
 		if (aux->native) {
 			aux->retry_cnt++;
 			if (!(aux->retry_cnt % MAX_AUX_RETRIES))
 				phy_calibrate(aux->phy);
 		}
 		/* reset aux if link is in connected state */
 		if (dp_catalog_link_is_connected(aux->catalog))
 			dp_catalog_aux_reset(aux->catalog);
 	} else {
 		aux->retry_cnt = 0;
 		switch (aux->aux_error_num) {
 		case DP_AUX_ERR_NONE:
 			if (aux->read)
 				ret = dp_aux_cmd_fifo_rx(aux, msg);
 			msg->reply = aux->native ? DP_AUX_NATIVE_REPLY_ACK : DP_AUX_I2C_REPLY_ACK;
 			break;
 		case DP_AUX_ERR_DEFER:
 			msg->reply = aux->native ? DP_AUX_NATIVE_REPLY_DEFER : DP_AUX_I2C_REPLY_DEFER;
 			break;
 		case DP_AUX_ERR_PHY:
 		case DP_AUX_ERR_ADDR:
 		case DP_AUX_ERR_NACK:
 		case DP_AUX_ERR_NACK_DEFER:
 			msg->reply = aux->native ? DP_AUX_NATIVE_REPLY_NACK : DP_AUX_I2C_REPLY_NACK;
 			break;
 		case DP_AUX_ERR_TOUT:
 			ret = -ETIMEDOUT;
 			break;
 		}
 	}

 	aux->cmd_busy = false;

 exit:
 	mutex_unlock(&aux->mutex);
 	pm_runtime_put_sync(dp_aux->dev);

 	return ret;
 }

 irqreturn_t dp_aux_isr(struct drm_dp_aux *dp_aux)
 {
 	u32 isr;
 	struct dp_aux_private *aux;

 	if (!dp_aux) {
 		DRM_ERROR("invalid input\n");
 		return IRQ_NONE;
 	}

 	aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

 	isr = dp_catalog_aux_get_irq(aux->catalog);

 	/* no interrupts pending, return immediately */
 	if (!isr)
 		return IRQ_NONE;

 	if (!aux->cmd_busy) {
 		DRM_ERROR("Unexpected DP AUX IRQ %#010x when not busy\n", isr);
 		return IRQ_NONE;
 	}

 	/*
 	 * The logic below assumes only one error bit is set (other than "done"
 	 * which can apparently be set at the same time as some of the other
 	 * bits). Warn if more than one get set so we know we need to improve
 	 * the logic.
 	 */
 	if (hweight32(isr & ~DP_INTR_AUX_XFER_DONE) > 1)
 		DRM_WARN("Some DP AUX interrupts unhandled: %#010x\n", isr);

 	if (isr & DP_INTR_AUX_ERROR) {
 		aux->aux_error_num = DP_AUX_ERR_PHY;
 		dp_catalog_aux_clear_hw_interrupts(aux->catalog);
 	} else if (isr & DP_INTR_NACK_DEFER) {
 		aux->aux_error_num = DP_AUX_ERR_NACK_DEFER;
 	} else if (isr & DP_INTR_WRONG_ADDR) {
 		aux->aux_error_num = DP_AUX_ERR_ADDR;
 	} else if (isr & DP_INTR_TIMEOUT) {
 		aux->aux_error_num = DP_AUX_ERR_TOUT;
 	} else if (!aux->native && (isr & DP_INTR_I2C_NACK)) {
 		aux->aux_error_num = DP_AUX_ERR_NACK;
 	} else if (!aux->native && (isr & DP_INTR_I2C_DEFER)) {
 		if (isr & DP_INTR_AUX_XFER_DONE)
 			aux->aux_error_num = DP_AUX_ERR_NACK;
 		else
 			aux->aux_error_num = DP_AUX_ERR_DEFER;
 	} else if (isr & DP_INTR_AUX_XFER_DONE) {
 		aux->aux_error_num = DP_AUX_ERR_NONE;
 	} else {
 		DRM_WARN("Unexpected interrupt: %#010x\n", isr);
 		return IRQ_NONE;
 	}

 	complete(&aux->comp);

 	return IRQ_HANDLED;
 }

 void dp_aux_enable_xfers(struct drm_dp_aux *dp_aux, bool enabled)
 {
 	struct dp_aux_private *aux;

 	aux = container_of(dp_aux, struct dp_aux_private, dp_aux);
 	aux->enable_xfers = enabled;
 }

 void dp_aux_reconfig(struct drm_dp_aux *dp_aux)
 {
 	struct dp_aux_private *aux;

 	aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

 	phy_calibrate(aux->phy);
 	dp_catalog_aux_reset(aux->catalog);
 }

 void dp_aux_init(struct drm_dp_aux *dp_aux)
 {
 	struct dp_aux_private *aux;

 	if (!dp_aux) {
 		DRM_ERROR("invalid input\n");
 		return;
 	}

 	aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

 	mutex_lock(&aux->mutex);

 	dp_catalog_aux_enable(aux->catalog, true);
 	aux->retry_cnt = 0;
 	aux->initted = true;

 	mutex_unlock(&aux->mutex);
 }

 void dp_aux_deinit(struct drm_dp_aux *dp_aux)
 {
 	struct dp_aux_private *aux;

 	aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

 	mutex_lock(&aux->mutex);

 	aux->initted = false;
 	dp_catalog_aux_enable(aux->catalog, false);

 	mutex_unlock(&aux->mutex);
 }

 int dp_aux_register(struct drm_dp_aux *dp_aux)
 {
 	int ret;

 	if (!dp_aux) {
 		DRM_ERROR("invalid input\n");
 		return -EINVAL;
 	}

 	ret = drm_dp_aux_register(dp_aux);
 	if (ret) {
 		DRM_ERROR("%s: failed to register drm aux: %d\n", __func__,
 				ret);
 		return ret;
 	}

 	return 0;
 }

 void dp_aux_unregister(struct drm_dp_aux *dp_aux)
 {
 	drm_dp_aux_unregister(dp_aux);
 }

 static int dp_wait_hpd_asserted(struct drm_dp_aux *dp_aux,
 				 unsigned long wait_us)
 {
 	int ret;
 	struct dp_aux_private *aux;

 	aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

 	pm_runtime_get_sync(aux->dev);
 	ret = dp_catalog_aux_wait_for_hpd_connect_state(aux->catalog, wait_us);
 	pm_runtime_put_sync(aux->dev);

 	return ret;
 }

 struct drm_dp_aux *dp_aux_get(struct device *dev, struct dp_catalog *catalog,
 			      struct phy *phy,
 			      bool is_edp)
 {
 	struct dp_aux_private *aux;

 	if (!catalog) {
 		DRM_ERROR("invalid input\n");
 		return ERR_PTR(-ENODEV);
 	}

 	aux = devm_kzalloc(dev, sizeof(*aux), GFP_KERNEL);
 	if (!aux)
 		return ERR_PTR(-ENOMEM);

 	init_completion(&aux->comp);
 	aux->cmd_busy = false;
 	aux->is_edp = is_edp;
 	mutex_init(&aux->mutex);

 	aux->dev = dev;
 	aux->catalog = catalog;
 	aux->phy = phy;
 	aux->retry_cnt = 0;

 	/*
 	 * Use the drm_dp_aux_init() to use the aux adapter
 	 * before registering AUX with the DRM device so that
 	 * msm eDP panel can be detected by generic_dep_panel_probe().
 	 */
 	aux->dp_aux.name = "dpu_dp_aux";
 	aux->dp_aux.dev = dev;
 	aux->dp_aux.transfer = dp_aux_transfer;
 	aux->dp_aux.wait_hpd_asserted = dp_wait_hpd_asserted;
 	drm_dp_aux_init(&aux->dp_aux);

 	return &aux->dp_aux;
 }

 void dp_aux_put(struct drm_dp_aux *dp_aux)
 {
 	struct dp_aux_private *aux;

 	if (!dp_aux)
 		return;

 	aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

 	mutex_destroy(&aux->mutex);

 	devm_kfree(aux->dev, aux);
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Copyright (c) 2012-2020, The Linux Foundation. All rights reserved.
	*/

	#include <linux/delay.h>
	#include <linux/phy/phy.h>
	#include <drm/drm_print.h>

	#include "dp_reg.h"
	#include "dp_aux.h"

	enum msm_dp_aux_err {
	DP_AUX_ERR_NONE,
	DP_AUX_ERR_ADDR,
	DP_AUX_ERR_TOUT,
	DP_AUX_ERR_NACK,
	DP_AUX_ERR_DEFER,
	DP_AUX_ERR_NACK_DEFER,
	DP_AUX_ERR_PHY,
	};

	struct dp_aux_private {
	struct device *dev;
	struct dp_catalog *catalog;

	struct phy *phy;

	struct mutex mutex;
	struct completion comp;

	enum msm_dp_aux_err aux_error_num;
	u32 retry_cnt;
	bool cmd_busy;
	bool native;
	bool read;
	bool no_send_addr;
	bool no_send_stop;
	bool initted;
	bool is_edp;
	bool enable_xfers;
	u32 offset;
	u32 segment;

	struct drm_dp_aux dp_aux;
	};

	#define MAX_AUX_RETRIES 5

	static ssize_t dp_aux_write(struct dp_aux_private *aux,
	struct drm_dp_aux_msg *msg)
	{
	u8 data[4];
	u32 reg;
	ssize_t len;
	u8 *msgdata = msg->buffer;
	int const AUX_CMD_FIFO_LEN = 128;
	int i = 0;

	if (aux->read)
	len = 0;
	else
	len = msg->size;

	/*
	* cmd fifo only has depth of 144 bytes
	* limit buf length to 128 bytes here
	*/
	if (len > AUX_CMD_FIFO_LEN - 4) {
	DRM_ERROR("buf size greater than allowed size of 128 bytes\n");
	return -EINVAL;
	}

	/* Pack cmd and write to HW */
	data[0] = (msg->address >> 16) & 0xf; /* addr[19:16] */
	if (aux->read)
	data[0] \|= BIT(4); /* R/W */

	data[1] = msg->address >> 8; /* addr[15:8] */
	data[2] = msg->address; /* addr[7:0] */
	data[3] = msg->size - 1; /* len[7:0] */

	for (i = 0; i < len + 4; i++) {
	reg = (i < 4) ? data[i] : msgdata[i - 4];
	reg <<= DP_AUX_DATA_OFFSET;
	reg &= DP_AUX_DATA_MASK;
	reg \|= DP_AUX_DATA_WRITE;
	/* index = 0, write */
	if (i == 0)
	reg \|= DP_AUX_DATA_INDEX_WRITE;
	dp_catalog_aux_write_data(aux->catalog, reg);
	}

	dp_catalog_aux_clear_trans(aux->catalog, false);
	dp_catalog_aux_clear_hw_interrupts(aux->catalog);

	reg = 0; /* Transaction number == 1 */
	if (!aux->native) { /* i2c */
	reg \|= DP_AUX_TRANS_CTRL_I2C;

	if (aux->no_send_addr)
	reg \|= DP_AUX_TRANS_CTRL_NO_SEND_ADDR;

	if (aux->no_send_stop)
	reg \|= DP_AUX_TRANS_CTRL_NO_SEND_STOP;
	}

	reg \|= DP_AUX_TRANS_CTRL_GO;
	dp_catalog_aux_write_trans(aux->catalog, reg);

	return len;
	}

	static ssize_t dp_aux_cmd_fifo_tx(struct dp_aux_private *aux,
	struct drm_dp_aux_msg *msg)
	{
	ssize_t ret;
	unsigned long time_left;

	reinit_completion(&aux->comp);

	ret = dp_aux_write(aux, msg);
	if (ret < 0)
	return ret;

	time_left = wait_for_completion_timeout(&aux->comp,
	msecs_to_jiffies(250));
	if (!time_left)
	return -ETIMEDOUT;

	return ret;
	}

	static ssize_t dp_aux_cmd_fifo_rx(struct dp_aux_private *aux,
	struct drm_dp_aux_msg *msg)
	{
	u32 data;
	u8 *dp;
	u32 i, actual_i;
	u32 len = msg->size;

	dp_catalog_aux_clear_trans(aux->catalog, true);

	data = DP_AUX_DATA_INDEX_WRITE; /* INDEX_WRITE */
	data \|= DP_AUX_DATA_READ; /* read */

	dp_catalog_aux_write_data(aux->catalog, data);

	dp = msg->buffer;

	/* discard first byte */
	data = dp_catalog_aux_read_data(aux->catalog);

	for (i = 0; i < len; i++) {
	data = dp_catalog_aux_read_data(aux->catalog);
	*dp++ = (u8)((data >> DP_AUX_DATA_OFFSET) & 0xff);

	actual_i = (data >> DP_AUX_DATA_INDEX_OFFSET) & 0xFF;
	if (i != actual_i)
	break;
	}

	return i;
	}

	static void dp_aux_update_offset_and_segment(struct dp_aux_private *aux,
	struct drm_dp_aux_msg *input_msg)
	{
	u32 edid_address = 0x50;
	u32 segment_address = 0x30;
	bool i2c_read = input_msg->request &
	(DP_AUX_I2C_READ & DP_AUX_NATIVE_READ);
	u8 *data;

	if (aux->native \|\| i2c_read \|\| ((input_msg->address != edid_address) &&
	(input_msg->address != segment_address)))
	return;


	data = input_msg->buffer;
	if (input_msg->address == segment_address)
	aux->segment = *data;
	else
	aux->offset = *data;
	}

	/**
	* dp_aux_transfer_helper() - helper function for EDID read transactions
	*
	* @aux: DP AUX private structure
	* @input_msg: input message from DRM upstream APIs
	* @send_seg: send the segment to sink
	*
	* return: void
	*
	* This helper function is used to fix EDID reads for non-compliant
	* sinks that do not handle the i2c middle-of-transaction flag correctly.
	*/
	static void dp_aux_transfer_helper(struct dp_aux_private *aux,
	struct drm_dp_aux_msg *input_msg,
	bool send_seg)
	{
	struct drm_dp_aux_msg helper_msg;
	u32 message_size = 0x10;
	u32 segment_address = 0x30;
	u32 const edid_block_length = 0x80;
	bool i2c_mot = input_msg->request & DP_AUX_I2C_MOT;
	bool i2c_read = input_msg->request &
	(DP_AUX_I2C_READ & DP_AUX_NATIVE_READ);

	if (!i2c_mot \|\| !i2c_read \|\| (input_msg->size == 0))
	return;

	/*
	* Sending the segment value and EDID offset will be performed
	* from the DRM upstream EDID driver for each block. Avoid
	* duplicate AUX transactions related to this while reading the
	* first 16 bytes of each block.
	*/
	if (!(aux->offset % edid_block_length) \|\| !send_seg)
	goto end;

	aux->read = false;
	aux->cmd_busy = true;
	aux->no_send_addr = true;
	aux->no_send_stop = true;

	/*
	* Send the segment address for every i2c read in which the
	* middle-of-tranaction flag is set. This is required to support EDID
	* reads of more than 2 blocks as the segment address is reset to 0
	* since we are overriding the middle-of-transaction flag for read
	* transactions.
	*/

	if (aux->segment) {
	memset(&helper_msg, 0, sizeof(helper_msg));
	helper_msg.address = segment_address;
	helper_msg.buffer = &aux->segment;
	helper_msg.size = 1;
	dp_aux_cmd_fifo_tx(aux, &helper_msg);
	}

	/*
	* Send the offset address for every i2c read in which the
	* middle-of-transaction flag is set. This will ensure that the sink
	* will update its read pointer and return the correct portion of the
	* EDID buffer in the subsequent i2c read trasntion triggered in the
	* native AUX transfer function.
	*/
	memset(&helper_msg, 0, sizeof(helper_msg));
	helper_msg.address = input_msg->address;
	helper_msg.buffer = &aux->offset;
	helper_msg.size = 1;
	dp_aux_cmd_fifo_tx(aux, &helper_msg);

	end:
	aux->offset += message_size;
	if (aux->offset == 0x80 \|\| aux->offset == 0x100)
	aux->segment = 0x0; /* reset segment at end of block */
	}

	/*
	* This function does the real job to process an AUX transaction.
	* It will call aux_reset() function to reset the AUX channel,
	* if the waiting is timeout.
	*/
	static ssize_t dp_aux_transfer(struct drm_dp_aux *dp_aux,
	struct drm_dp_aux_msg *msg)
	{
	ssize_t ret;
	int const aux_cmd_native_max = 16;
	int const aux_cmd_i2c_max = 128;
	struct dp_aux_private *aux;

	aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

	aux->native = msg->request & (DP_AUX_NATIVE_WRITE & DP_AUX_NATIVE_READ);

	/* Ignore address only message */
	if (msg->size == 0 \|\| !msg->buffer) {
	msg->reply = aux->native ?
	DP_AUX_NATIVE_REPLY_ACK : DP_AUX_I2C_REPLY_ACK;
	return msg->size;
	}

	/* msg sanity check */
	if ((aux->native && msg->size > aux_cmd_native_max) \|\|
	msg->size > aux_cmd_i2c_max) {
	DRM_ERROR("%s: invalid msg: size(%zu), request(%x)\n",
	__func__, msg->size, msg->request);
	return -EINVAL;
	}

	ret = pm_runtime_resume_and_get(dp_aux->dev);
	if (ret)
	return ret;

	mutex_lock(&aux->mutex);
	if (!aux->initted) {
	ret = -EIO;
	goto exit;
	}

	/*
	* If we're using DP and an external display isn't connected then the
	* transfer won't succeed. Return right away. If we don't do this we
	* can end up with long timeouts if someone tries to access the DP AUX
	* character device when no DP device is connected.
	*/
	if (!aux->is_edp && !aux->enable_xfers) {
	ret = -ENXIO;
	goto exit;
	}

	dp_aux_update_offset_and_segment(aux, msg);
	dp_aux_transfer_helper(aux, msg, true);

	aux->read = msg->request & (DP_AUX_I2C_READ & DP_AUX_NATIVE_READ);
	aux->cmd_busy = true;

	if (aux->read) {
	aux->no_send_addr = true;
	aux->no_send_stop = false;
	} else {
	aux->no_send_addr = true;
	aux->no_send_stop = true;
	}

	ret = dp_aux_cmd_fifo_tx(aux, msg);
	if (ret < 0) {
	if (aux->native) {
	aux->retry_cnt++;
	if (!(aux->retry_cnt % MAX_AUX_RETRIES))
	phy_calibrate(aux->phy);
	}
	/* reset aux if link is in connected state */
	if (dp_catalog_link_is_connected(aux->catalog))
	dp_catalog_aux_reset(aux->catalog);
	} else {
	aux->retry_cnt = 0;
	switch (aux->aux_error_num) {
	case DP_AUX_ERR_NONE:
	if (aux->read)
	ret = dp_aux_cmd_fifo_rx(aux, msg);
	msg->reply = aux->native ? DP_AUX_NATIVE_REPLY_ACK : DP_AUX_I2C_REPLY_ACK;
	break;
	case DP_AUX_ERR_DEFER:
	msg->reply = aux->native ? DP_AUX_NATIVE_REPLY_DEFER : DP_AUX_I2C_REPLY_DEFER;
	break;
	case DP_AUX_ERR_PHY:
	case DP_AUX_ERR_ADDR:
	case DP_AUX_ERR_NACK:
	case DP_AUX_ERR_NACK_DEFER:
	msg->reply = aux->native ? DP_AUX_NATIVE_REPLY_NACK : DP_AUX_I2C_REPLY_NACK;
	break;
	case DP_AUX_ERR_TOUT:
	ret = -ETIMEDOUT;
	break;
	}
	}

	aux->cmd_busy = false;

	exit:
	mutex_unlock(&aux->mutex);
	pm_runtime_put_sync(dp_aux->dev);

	return ret;
	}

	irqreturn_t dp_aux_isr(struct drm_dp_aux *dp_aux)
	{
	u32 isr;
	struct dp_aux_private *aux;

	if (!dp_aux) {
	DRM_ERROR("invalid input\n");
	return IRQ_NONE;
	}

	aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

	isr = dp_catalog_aux_get_irq(aux->catalog);

	/* no interrupts pending, return immediately */
	if (!isr)
	return IRQ_NONE;

	if (!aux->cmd_busy) {
	DRM_ERROR("Unexpected DP AUX IRQ %#010x when not busy\n", isr);
	return IRQ_NONE;
	}

	/*
	* The logic below assumes only one error bit is set (other than "done"
	* which can apparently be set at the same time as some of the other
	* bits). Warn if more than one get set so we know we need to improve
	* the logic.
	*/
	if (hweight32(isr & ~DP_INTR_AUX_XFER_DONE) > 1)
	DRM_WARN("Some DP AUX interrupts unhandled: %#010x\n", isr);

	if (isr & DP_INTR_AUX_ERROR) {
	aux->aux_error_num = DP_AUX_ERR_PHY;
	dp_catalog_aux_clear_hw_interrupts(aux->catalog);
	} else if (isr & DP_INTR_NACK_DEFER) {
	aux->aux_error_num = DP_AUX_ERR_NACK_DEFER;
	} else if (isr & DP_INTR_WRONG_ADDR) {
	aux->aux_error_num = DP_AUX_ERR_ADDR;
	} else if (isr & DP_INTR_TIMEOUT) {
	aux->aux_error_num = DP_AUX_ERR_TOUT;
	} else if (!aux->native && (isr & DP_INTR_I2C_NACK)) {
	aux->aux_error_num = DP_AUX_ERR_NACK;
	} else if (!aux->native && (isr & DP_INTR_I2C_DEFER)) {
	if (isr & DP_INTR_AUX_XFER_DONE)
	aux->aux_error_num = DP_AUX_ERR_NACK;
	else
	aux->aux_error_num = DP_AUX_ERR_DEFER;
	} else if (isr & DP_INTR_AUX_XFER_DONE) {
	aux->aux_error_num = DP_AUX_ERR_NONE;
	} else {
	DRM_WARN("Unexpected interrupt: %#010x\n", isr);
	return IRQ_NONE;
	}

	complete(&aux->comp);

	return IRQ_HANDLED;
	}

	void dp_aux_enable_xfers(struct drm_dp_aux *dp_aux, bool enabled)
	{
	struct dp_aux_private *aux;

	aux = container_of(dp_aux, struct dp_aux_private, dp_aux);
	aux->enable_xfers = enabled;
	}

	void dp_aux_reconfig(struct drm_dp_aux *dp_aux)
	{
	struct dp_aux_private *aux;

	aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

	phy_calibrate(aux->phy);
	dp_catalog_aux_reset(aux->catalog);
	}

	void dp_aux_init(struct drm_dp_aux *dp_aux)
	{
	struct dp_aux_private *aux;

	if (!dp_aux) {
	DRM_ERROR("invalid input\n");
	return;
	}

	aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

	mutex_lock(&aux->mutex);

	dp_catalog_aux_enable(aux->catalog, true);
	aux->retry_cnt = 0;
	aux->initted = true;

	mutex_unlock(&aux->mutex);
	}

	void dp_aux_deinit(struct drm_dp_aux *dp_aux)
	{
	struct dp_aux_private *aux;

	aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

	mutex_lock(&aux->mutex);

	aux->initted = false;
	dp_catalog_aux_enable(aux->catalog, false);

	mutex_unlock(&aux->mutex);
	}

	int dp_aux_register(struct drm_dp_aux *dp_aux)
	{
	int ret;

	if (!dp_aux) {
	DRM_ERROR("invalid input\n");
	return -EINVAL;
	}

	ret = drm_dp_aux_register(dp_aux);
	if (ret) {
	DRM_ERROR("%s: failed to register drm aux: %d\n", __func__,
	ret);
	return ret;
	}

	return 0;
	}

	void dp_aux_unregister(struct drm_dp_aux *dp_aux)
	{
	drm_dp_aux_unregister(dp_aux);
	}

	static int dp_wait_hpd_asserted(struct drm_dp_aux *dp_aux,
	unsigned long wait_us)
	{
	int ret;
	struct dp_aux_private *aux;

	aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

	pm_runtime_get_sync(aux->dev);
	ret = dp_catalog_aux_wait_for_hpd_connect_state(aux->catalog, wait_us);
	pm_runtime_put_sync(aux->dev);

	return ret;
	}

	struct drm_dp_aux dp_aux_get(struct device dev, struct dp_catalog *catalog,
	struct phy *phy,
	bool is_edp)
	{
	struct dp_aux_private *aux;

	if (!catalog) {
	DRM_ERROR("invalid input\n");
	return ERR_PTR(-ENODEV);
	}

	aux = devm_kzalloc(dev, sizeof(*aux), GFP_KERNEL);
	if (!aux)
	return ERR_PTR(-ENOMEM);

	init_completion(&aux->comp);
	aux->cmd_busy = false;
	aux->is_edp = is_edp;
	mutex_init(&aux->mutex);

	aux->dev = dev;
	aux->catalog = catalog;
	aux->phy = phy;
	aux->retry_cnt = 0;

	/*
	* Use the drm_dp_aux_init() to use the aux adapter
	* before registering AUX with the DRM device so that
	* msm eDP panel can be detected by generic_dep_panel_probe().
	*/
	aux->dp_aux.name = "dpu_dp_aux";
	aux->dp_aux.dev = dev;
	aux->dp_aux.transfer = dp_aux_transfer;
	aux->dp_aux.wait_hpd_asserted = dp_wait_hpd_asserted;
	drm_dp_aux_init(&aux->dp_aux);

	return &aux->dp_aux;
	}

	void dp_aux_put(struct drm_dp_aux *dp_aux)
	{
	struct dp_aux_private *aux;

	if (!dp_aux)
	return;

	aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

	mutex_destroy(&aux->mutex);

	devm_kfree(aux->dev, aux);
	}