/*
 * Copyright 2019 Advanced Micro Devices, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 */

#include "smuio/smuio_11_0_0_offset.h"
#include "smuio/smuio_11_0_0_sh_mask.h"

#include "smu_v11_0_i2c.h"
#include "amdgpu.h"
#include "soc15_common.h"
#include <drm/drm_fixed.h>
#include <drm/drm_drv.h>
#include "amdgpu_amdkfd.h"
#include <linux/i2c.h>
#include <linux/pci.h>

/* error codes */
#define I2C_OK                0
#define I2C_NAK_7B_ADDR_NOACK 1
#define I2C_NAK_TXDATA_NOACK  2
#define I2C_TIMEOUT           4
#define I2C_SW_TIMEOUT        8
#define I2C_ABORT             0x10

#define I2C_X_RESTART         BIT(31)

#define to_amdgpu_device(x) (container_of(x, struct amdgpu_device, pm.smu_i2c))

static void smu_v11_0_i2c_set_clock_gating(struct i2c_adapter *control, bool en)
{
	struct amdgpu_device *adev = to_amdgpu_device(control);
	uint32_t reg = RREG32_SOC15(SMUIO, 0, mmSMUIO_PWRMGT);

	reg = REG_SET_FIELD(reg, SMUIO_PWRMGT, i2c_clk_gate_en, en ? 1 : 0);
	WREG32_SOC15(SMUIO, 0, mmSMUIO_PWRMGT, reg);
}

/* The T_I2C_POLL_US is defined as follows:
 *
 * "Define a timer interval (t_i2c_poll) equal to 10 times the
 *  signalling period for the highest I2C transfer speed used in the
 *  system and supported by DW_apb_i2c. For instance, if the highest
 *  I2C data transfer mode is 400 kb/s, then t_i2c_poll is 25 us."  --
 * DesignWare DW_apb_i2c Databook, Version 1.21a, section 3.8.3.1,
 * page 56, with grammar and syntax corrections.
 *
 * Vcc for our device is at 1.8V which puts it at 400 kHz,
 * see Atmel AT24CM02 datasheet, section 8.3 DC Characteristics table, page 14.
 *
 * The procedure to disable the IP block is described in section
 * 3.8.3 Disabling DW_apb_i2c on page 56.
 */
#define I2C_SPEED_MODE_FAST     2
#define T_I2C_POLL_US           25
#define I2C_MAX_T_POLL_COUNT    1000

static int smu_v11_0_i2c_enable(struct i2c_adapter *control, bool enable)
{
	struct amdgpu_device *adev = to_amdgpu_device(control);

	WREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_ENABLE, enable ? 1 : 0);

	if (!enable) {
		int ii;

		for (ii = I2C_MAX_T_POLL_COUNT; ii > 0; ii--) {
			u32 en_stat = RREG32_SOC15(SMUIO,
						   0,
						   mmCKSVII2C_IC_ENABLE_STATUS);
			if (REG_GET_FIELD(en_stat, CKSVII2C_IC_ENABLE_STATUS, IC_EN))
				udelay(T_I2C_POLL_US);
			else
				return I2C_OK;
		}

		return I2C_ABORT;
	}

	return I2C_OK;
}

static void smu_v11_0_i2c_clear_status(struct i2c_adapter *control)
{
	struct amdgpu_device *adev = to_amdgpu_device(control);
	/* do */
	{
		RREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_CLR_INTR);

	} /* while (reg_CKSVII2C_ic_clr_intr == 0) */
}

static void smu_v11_0_i2c_configure(struct i2c_adapter *control)
{
	struct amdgpu_device *adev = to_amdgpu_device(control);
	uint32_t reg = 0;

	reg = REG_SET_FIELD(reg, CKSVII2C_IC_CON, IC_SLAVE_DISABLE, 1);
	reg = REG_SET_FIELD(reg, CKSVII2C_IC_CON, IC_RESTART_EN, 1);
	reg = REG_SET_FIELD(reg, CKSVII2C_IC_CON, IC_10BITADDR_MASTER, 0);
	reg = REG_SET_FIELD(reg, CKSVII2C_IC_CON, IC_10BITADDR_SLAVE, 0);
	/* The values of IC_MAX_SPEED_MODE are,
	 * 1: standard mode, 0 - 100 Kb/s,
	 * 2: fast mode, <= 400 Kb/s, or fast mode plus, <= 1000 Kb/s,
	 * 3: high speed mode, <= 3.4 Mb/s.
	 */
	reg = REG_SET_FIELD(reg, CKSVII2C_IC_CON, IC_MAX_SPEED_MODE,
			    I2C_SPEED_MODE_FAST);
	reg = REG_SET_FIELD(reg, CKSVII2C_IC_CON, IC_MASTER_MODE, 1);

	WREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_CON, reg);
}

static void smu_v11_0_i2c_set_clock(struct i2c_adapter *control)
{
	struct amdgpu_device *adev = to_amdgpu_device(control);

	/*
	 * Standard mode speed, These values are taken from SMUIO MAS,
	 * but are different from what is given is
	 * Synopsys spec. The values here are based on assumption
	 * that refclock is 100MHz
	 *
	 * Configuration for standard mode; Speed = 100kbps
	 * Scale linearly, for now only support standard speed clock
	 * This will work only with 100M ref clock
	 *
	 * TBD:Change the calculation to take into account ref clock values also.
	 */

	WREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_FS_SPKLEN, 2);
	WREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_SS_SCL_HCNT, 120);
	WREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_SS_SCL_LCNT, 130);
	WREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_SDA_HOLD, 20);
}

static void smu_v11_0_i2c_set_address(struct i2c_adapter *control, u16 address)
{
	struct amdgpu_device *adev = to_amdgpu_device(control);

	/* The IC_TAR::IC_TAR field is 10-bits wide.
	 * It takes a 7-bit or 10-bit addresses as an address,
	 * i.e. no read/write bit--no wire format, just the address.
	 */
	WREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_TAR, address & 0x3FF);
}

static uint32_t smu_v11_0_i2c_poll_tx_status(struct i2c_adapter *control)
{
	struct amdgpu_device *adev = to_amdgpu_device(control);
	uint32_t ret = I2C_OK;
	uint32_t reg, reg_c_tx_abrt_source;

	/*Check if transmission is completed */
	unsigned long  timeout_counter = jiffies + msecs_to_jiffies(20);

	do {
		if (time_after(jiffies, timeout_counter)) {
			ret |= I2C_SW_TIMEOUT;
			break;
		}

		reg = RREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_STATUS);

	} while (REG_GET_FIELD(reg, CKSVII2C_IC_STATUS, TFE) == 0);

	if (ret != I2C_OK)
		return ret;

	/* This only checks if NAK is received and transaction got aborted */
	reg = RREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_INTR_STAT);

	if (REG_GET_FIELD(reg, CKSVII2C_IC_INTR_STAT, R_TX_ABRT) == 1) {
		reg_c_tx_abrt_source = RREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_TX_ABRT_SOURCE);
		DRM_INFO("TX was terminated, IC_TX_ABRT_SOURCE val is:%x", reg_c_tx_abrt_source);

		/* Check for stop due to NACK */
		if (REG_GET_FIELD(reg_c_tx_abrt_source,
				  CKSVII2C_IC_TX_ABRT_SOURCE,
				  ABRT_TXDATA_NOACK) == 1) {

			ret |= I2C_NAK_TXDATA_NOACK;

		} else if (REG_GET_FIELD(reg_c_tx_abrt_source,
					 CKSVII2C_IC_TX_ABRT_SOURCE,
					 ABRT_7B_ADDR_NOACK) == 1) {

			ret |= I2C_NAK_7B_ADDR_NOACK;
		} else {
			ret |= I2C_ABORT;
		}

		smu_v11_0_i2c_clear_status(control);
	}

	return ret;
}

static uint32_t smu_v11_0_i2c_poll_rx_status(struct i2c_adapter *control)
{
	struct amdgpu_device *adev = to_amdgpu_device(control);
	uint32_t ret = I2C_OK;
	uint32_t reg_ic_status, reg_c_tx_abrt_source;

	reg_c_tx_abrt_source = RREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_TX_ABRT_SOURCE);

	/* If slave is not present */
	if (REG_GET_FIELD(reg_c_tx_abrt_source,
			  CKSVII2C_IC_TX_ABRT_SOURCE,
			  ABRT_7B_ADDR_NOACK) == 1) {
		ret |= I2C_NAK_7B_ADDR_NOACK;

		smu_v11_0_i2c_clear_status(control);
	} else {  /* wait till some data is there in RXFIFO */
		/* Poll for some byte in RXFIFO */
		unsigned long  timeout_counter = jiffies + msecs_to_jiffies(20);

		do {
			if (time_after(jiffies, timeout_counter)) {
				ret |= I2C_SW_TIMEOUT;
				break;
			}

			reg_ic_status = RREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_STATUS);

		} while (REG_GET_FIELD(reg_ic_status, CKSVII2C_IC_STATUS, RFNE) == 0);
	}

	return ret;
}

/**
 * smu_v11_0_i2c_transmit - Send a block of data over the I2C bus to a slave device.
 *
 * @control: I2C adapter reference
 * @address: The I2C address of the slave device.
 * @data: The data to transmit over the bus.
 * @numbytes: The amount of data to transmit.
 * @i2c_flag: Flags for transmission
 *
 * Returns 0 on success or error.
 */
static uint32_t smu_v11_0_i2c_transmit(struct i2c_adapter *control,
				       u16 address, u8 *data,
				       u32 numbytes, u32 i2c_flag)
{
	struct amdgpu_device *adev = to_amdgpu_device(control);
	u32 bytes_sent, reg, ret = I2C_OK;
	unsigned long  timeout_counter;

	bytes_sent = 0;

	DRM_DEBUG_DRIVER("I2C_Transmit(), address = %x, bytes = %d , data: ",
			 address, numbytes);

	if (drm_debug_enabled(DRM_UT_DRIVER)) {
		print_hex_dump(KERN_INFO, "data: ", DUMP_PREFIX_NONE,
			       16, 1, data, numbytes, false);
	}

	/* Set the I2C slave address */
	smu_v11_0_i2c_set_address(control, address);
	/* Enable I2C */
	smu_v11_0_i2c_enable(control, true);

	/* Clear status bits */
	smu_v11_0_i2c_clear_status(control);

	timeout_counter = jiffies + msecs_to_jiffies(20);

	while (numbytes > 0) {
		reg = RREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_STATUS);
		if (!REG_GET_FIELD(reg, CKSVII2C_IC_STATUS, TFNF)) {
			/*
			 * We waited for too long for the transmission
			 * FIFO to become not-full.  Exit the loop
			 * with error.
			 */
			if (time_after(jiffies, timeout_counter)) {
				ret |= I2C_SW_TIMEOUT;
				goto Err;
			}
		} else {
			reg = REG_SET_FIELD(reg, CKSVII2C_IC_DATA_CMD, DAT,
					    data[bytes_sent]);

			/* Final message, final byte, must generate a
			 * STOP to release the bus, i.e. don't hold
			 * SCL low.
			 */
			if (numbytes == 1 && i2c_flag & I2C_M_STOP)
				reg = REG_SET_FIELD(reg,
						    CKSVII2C_IC_DATA_CMD,
						    STOP, 1);

			if (bytes_sent == 0 && i2c_flag & I2C_X_RESTART)
				reg = REG_SET_FIELD(reg,
						    CKSVII2C_IC_DATA_CMD,
						    RESTART, 1);

			/* Write */
			reg = REG_SET_FIELD(reg, CKSVII2C_IC_DATA_CMD, CMD, 0);
			WREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_DATA_CMD, reg);

			/* Record that the bytes were transmitted */
			bytes_sent++;
			numbytes--;
		}
	}

	ret = smu_v11_0_i2c_poll_tx_status(control);
Err:
	/* Any error, no point in proceeding */
	if (ret != I2C_OK) {
		if (ret & I2C_SW_TIMEOUT)
			DRM_ERROR("TIMEOUT ERROR !!!");

		if (ret & I2C_NAK_7B_ADDR_NOACK)
			DRM_ERROR("Received I2C_NAK_7B_ADDR_NOACK !!!");


		if (ret & I2C_NAK_TXDATA_NOACK)
			DRM_ERROR("Received I2C_NAK_TXDATA_NOACK !!!");
	}

	return ret;
}


/**
 * smu_v11_0_i2c_receive - Receive a block of data over the I2C bus from a slave device.
 *
 * @control: I2C adapter reference
 * @address: The I2C address of the slave device.
 * @data: Placeholder to store received data.
 * @numbytes: The amount of data to transmit.
 * @i2c_flag: Flags for transmission
 *
 * Returns 0 on success or error.
 */
static uint32_t smu_v11_0_i2c_receive(struct i2c_adapter *control,
				      u16 address, u8 *data,
				      u32 numbytes, u32 i2c_flag)
{
	struct amdgpu_device *adev = to_amdgpu_device(control);
	uint32_t bytes_received, ret = I2C_OK;

	bytes_received = 0;

	/* Set the I2C slave address */
	smu_v11_0_i2c_set_address(control, address);

	/* Enable I2C */
	smu_v11_0_i2c_enable(control, true);

	while (numbytes > 0) {
		uint32_t reg = 0;

		smu_v11_0_i2c_clear_status(control);

		/* Prepare transaction */
		reg = REG_SET_FIELD(reg, CKSVII2C_IC_DATA_CMD, DAT, 0);
		/* Read */
		reg = REG_SET_FIELD(reg, CKSVII2C_IC_DATA_CMD, CMD, 1);

		/* Final message, final byte, must generate a STOP
		 * to release the bus, i.e. don't hold SCL low.
		 */
		if (numbytes == 1 && i2c_flag & I2C_M_STOP)
			reg = REG_SET_FIELD(reg, CKSVII2C_IC_DATA_CMD,
					    STOP, 1);

		if (bytes_received == 0 && i2c_flag & I2C_X_RESTART)
			reg = REG_SET_FIELD(reg, CKSVII2C_IC_DATA_CMD,
					    RESTART, 1);

		WREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_DATA_CMD, reg);

		ret = smu_v11_0_i2c_poll_rx_status(control);

		/* Any error, no point in proceeding */
		if (ret != I2C_OK) {
			if (ret & I2C_SW_TIMEOUT)
				DRM_ERROR("TIMEOUT ERROR !!!");

			if (ret & I2C_NAK_7B_ADDR_NOACK)
				DRM_ERROR("Received I2C_NAK_7B_ADDR_NOACK !!!");

			if (ret & I2C_NAK_TXDATA_NOACK)
				DRM_ERROR("Received I2C_NAK_TXDATA_NOACK !!!");

			break;
		}

		reg = RREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_DATA_CMD);
		data[bytes_received] = REG_GET_FIELD(reg, CKSVII2C_IC_DATA_CMD, DAT);

		/* Record that the bytes were received */
		bytes_received++;
		numbytes--;
	}

	DRM_DEBUG_DRIVER("I2C_Receive(), address = %x, bytes = %d, data :",
		  (uint16_t)address, bytes_received);

	if (drm_debug_enabled(DRM_UT_DRIVER)) {
		print_hex_dump(KERN_INFO, "data: ", DUMP_PREFIX_NONE,
			       16, 1, data, bytes_received, false);
	}

	return ret;
}

static void smu_v11_0_i2c_abort(struct i2c_adapter *control)
{
	struct amdgpu_device *adev = to_amdgpu_device(control);
	uint32_t reg = 0;

	/* Enable I2C engine; */
	reg = REG_SET_FIELD(reg, CKSVII2C_IC_ENABLE, ENABLE, 1);
	WREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_ENABLE, reg);

	/* Abort previous transaction */
	reg = REG_SET_FIELD(reg, CKSVII2C_IC_ENABLE, ABORT, 1);
	WREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_ENABLE, reg);

	DRM_DEBUG_DRIVER("I2C_Abort() Done.");
}

static bool smu_v11_0_i2c_activity_done(struct i2c_adapter *control)
{
	struct amdgpu_device *adev = to_amdgpu_device(control);

	const uint32_t IDLE_TIMEOUT = 1024;
	uint32_t timeout_count = 0;
	uint32_t reg_ic_enable, reg_ic_enable_status, reg_ic_clr_activity;

	reg_ic_enable_status = RREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_ENABLE_STATUS);
	reg_ic_enable = RREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_ENABLE);

	if ((REG_GET_FIELD(reg_ic_enable, CKSVII2C_IC_ENABLE, ENABLE) == 0) &&
	    (REG_GET_FIELD(reg_ic_enable_status, CKSVII2C_IC_ENABLE_STATUS, IC_EN) == 1)) {
		/*
		 * Nobody is using I2C engine, but engine remains active because
		 * someone missed to send STOP
		 */
		smu_v11_0_i2c_abort(control);
	} else if (REG_GET_FIELD(reg_ic_enable, CKSVII2C_IC_ENABLE, ENABLE) == 0) {
		/* Nobody is using I2C engine */
		return true;
	}

	/* Keep reading activity bit until it's cleared */
	do {
		reg_ic_clr_activity = RREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_CLR_ACTIVITY);

		if (REG_GET_FIELD(reg_ic_clr_activity,
		    CKSVII2C_IC_CLR_ACTIVITY, CLR_ACTIVITY) == 0)
			return true;

		++timeout_count;

	} while (timeout_count < IDLE_TIMEOUT);

	return false;
}

static void smu_v11_0_i2c_init(struct i2c_adapter *control)
{
	int res;

	/* Disable clock gating */
	smu_v11_0_i2c_set_clock_gating(control, false);

	if (!smu_v11_0_i2c_activity_done(control))
		DRM_WARN("I2C busy !");

	/* Disable I2C */
	res = smu_v11_0_i2c_enable(control, false);
	if (res != I2C_OK)
		smu_v11_0_i2c_abort(control);

	/* Configure I2C to operate as master and in standard mode */
	smu_v11_0_i2c_configure(control);

	/* Initialize the clock to 50 kHz default */
	smu_v11_0_i2c_set_clock(control);

}

static void smu_v11_0_i2c_fini(struct i2c_adapter *control)
{
	struct amdgpu_device *adev = to_amdgpu_device(control);
	u32 status, enable, en_stat;
	int res;

	res = smu_v11_0_i2c_enable(control, false);
	if (res != I2C_OK) {
		status  = RREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_STATUS);
		enable  = RREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_ENABLE);
		en_stat = RREG32_SOC15(SMUIO, 0, mmCKSVII2C_IC_ENABLE_STATUS);

		/* Nobody is using the I2C engine, yet it remains
		 * active, possibly because someone missed to send
		 * STOP.
		 */
		DRM_DEBUG_DRIVER("Aborting from fini: status:0x%08x "
				 "enable:0x%08x enable_stat:0x%08x",
				 status, enable, en_stat);
		smu_v11_0_i2c_abort(control);
	}

	/* Restore clock gating */

	/*
	 * TODO Reenabling clock gating seems to break subsequent SMU operation
	 *      on the I2C bus. My guess is that SMU doesn't disable clock gating like
	 *      we do here before working with the bus. So for now just don't restore
	 *      it but later work with SMU to see if they have this issue and can
	 *      update their code appropriately
	 */
	/* smu_v11_0_i2c_set_clock_gating(control, true); */

}

static bool smu_v11_0_i2c_bus_lock(struct i2c_adapter *control)
{
	struct amdgpu_device *adev = to_amdgpu_device(control);

	/* Send  PPSMC_MSG_RequestI2CBus */
	if (!amdgpu_dpm_smu_i2c_bus_access(adev, true))
		return true;

	return false;
}

static bool smu_v11_0_i2c_bus_unlock(struct i2c_adapter *control)
{
	struct amdgpu_device *adev = to_amdgpu_device(control);

	/* Send  PPSMC_MSG_ReleaseI2CBus */
	if (!amdgpu_dpm_smu_i2c_bus_access(adev, false))
		return true;

	return false;
}

/***************************** I2C GLUE ****************************/

static uint32_t smu_v11_0_i2c_read_data(struct i2c_adapter *control,
					struct i2c_msg *msg, uint32_t i2c_flag)
{
	uint32_t  ret;

	ret = smu_v11_0_i2c_receive(control, msg->addr, msg->buf, msg->len, i2c_flag);

	if (ret != I2C_OK)
		DRM_ERROR("ReadData() - I2C error occurred :%x", ret);

	return ret;
}

static uint32_t smu_v11_0_i2c_write_data(struct i2c_adapter *control,
					struct i2c_msg *msg, uint32_t i2c_flag)
{
	uint32_t  ret;

	ret = smu_v11_0_i2c_transmit(control, msg->addr, msg->buf, msg->len, i2c_flag);

	if (ret != I2C_OK)
		DRM_ERROR("WriteI2CData() - I2C error occurred :%x", ret);
	
	return ret;

}

static void lock_bus(struct i2c_adapter *i2c, unsigned int flags)
{
	struct amdgpu_device *adev = to_amdgpu_device(i2c);

	mutex_lock(&adev->pm.smu_i2c_mutex);
	if (!smu_v11_0_i2c_bus_lock(i2c))
		DRM_ERROR("Failed to lock the bus from SMU");
	else
		adev->pm.bus_locked = true;
}

static int trylock_bus(struct i2c_adapter *i2c, unsigned int flags)
{
	WARN_ONCE(1, "This operation not supposed to run in atomic context!");
	return false;
}

static void unlock_bus(struct i2c_adapter *i2c, unsigned int flags)
{
	struct amdgpu_device *adev = to_amdgpu_device(i2c);

	if (!smu_v11_0_i2c_bus_unlock(i2c))
		DRM_ERROR("Failed to unlock the bus from SMU");
	else
		adev->pm.bus_locked = false;
	mutex_unlock(&adev->pm.smu_i2c_mutex);
}

static const struct i2c_lock_operations smu_v11_0_i2c_i2c_lock_ops = {
	.lock_bus = lock_bus,
	.trylock_bus = trylock_bus,
	.unlock_bus = unlock_bus,
};

static int smu_v11_0_i2c_xfer(struct i2c_adapter *i2c_adap,
			      struct i2c_msg *msg, int num)
{
	int i, ret;
	u16 addr, dir;

	smu_v11_0_i2c_init(i2c_adap);

	/* From the client's point of view, this sequence of
	 * messages-- the array i2c_msg *msg, is a single transaction
	 * on the bus, starting with START and ending with STOP.
	 *
	 * The client is welcome to send any sequence of messages in
	 * this array, as processing under this function here is
	 * striving to be agnostic.
	 *
	 * Record the first address and direction we see. If either
	 * changes for a subsequent message, generate ReSTART. The
	 * DW_apb_i2c databook, v1.21a, specifies that ReSTART is
	 * generated when the direction changes, with the default IP
	 * block parameter settings, but it doesn't specify if ReSTART
	 * is generated when the address changes (possibly...). We
	 * don't rely on the default IP block parameter settings as
	 * the block is shared and they may change.
	 */
	if (num > 0) {
		addr = msg[0].addr;
		dir  = msg[0].flags & I2C_M_RD;
	}

	for (i = 0; i < num; i++) {
		u32 i2c_flag = 0;

		if (msg[i].addr != addr || (msg[i].flags ^ dir) & I2C_M_RD) {
			addr = msg[i].addr;
			dir  = msg[i].flags & I2C_M_RD;
			i2c_flag |= I2C_X_RESTART;
		}

		if (i == num - 1) {
			/* Set the STOP bit on the last message, so
			 * that the IP block generates a STOP after
			 * the last byte of the message.
			 */
			i2c_flag |= I2C_M_STOP;
		}

		if (msg[i].flags & I2C_M_RD)
			ret = smu_v11_0_i2c_read_data(i2c_adap,
						      msg + i,
						      i2c_flag);
		else
			ret = smu_v11_0_i2c_write_data(i2c_adap,
						       msg + i,
						       i2c_flag);

		if (ret != I2C_OK) {
			num = -EIO;
			break;
		}
	}

	smu_v11_0_i2c_fini(i2c_adap);
	return num;
}

static u32 smu_v11_0_i2c_func(struct i2c_adapter *adap)
{
	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}

static const struct i2c_algorithm smu_v11_0_i2c_algo = {
	.master_xfer = smu_v11_0_i2c_xfer,
	.functionality = smu_v11_0_i2c_func,
};

static const struct i2c_adapter_quirks smu_v11_0_i2c_control_quirks = {
	.flags = I2C_AQ_NO_ZERO_LEN,
};

int smu_v11_0_i2c_control_init(struct i2c_adapter *control)
{
	struct amdgpu_device *adev = to_amdgpu_device(control);
	int res;

	mutex_init(&adev->pm.smu_i2c_mutex);
	control->owner = THIS_MODULE;
	control->class = I2C_CLASS_HWMON;
	control->dev.parent = &adev->pdev->dev;
	control->algo = &smu_v11_0_i2c_algo;
	snprintf(control->name, sizeof(control->name), "AMDGPU SMU");
	control->lock_ops = &smu_v11_0_i2c_i2c_lock_ops;
	control->quirks = &smu_v11_0_i2c_control_quirks;

	res = i2c_add_adapter(control);
	if (res)
		DRM_ERROR("Failed to register hw i2c, err: %d\n", res);

	return res;
}

void smu_v11_0_i2c_control_fini(struct i2c_adapter *control)
{
	i2c_del_adapter(control);
}

/*
 * Keep this for future unit test if bugs arise
 */
#if 0
#define I2C_TARGET_ADDR 0xA0

bool smu_v11_0_i2c_test_bus(struct i2c_adapter *control)
{

	uint32_t ret = I2C_OK;
	uint8_t data[6] = {0xf, 0, 0xde, 0xad, 0xbe, 0xef};


	DRM_INFO("Begin");

	if (!smu_v11_0_i2c_bus_lock(control)) {
		DRM_ERROR("Failed to lock the bus!.");
		return false;
	}

	smu_v11_0_i2c_init(control);

	/* Write 0xde to address 0x0000 on the EEPROM */
	ret = smu_v11_0_i2c_write_data(control, I2C_TARGET_ADDR, data, 6);

	ret = smu_v11_0_i2c_read_data(control, I2C_TARGET_ADDR, data, 6);

	smu_v11_0_i2c_fini(control);

	smu_v11_0_i2c_bus_unlock(control);


	DRM_INFO("End");
	return true;
}
#endif