/*
 * 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