// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2009-2013, 2016-2018, The Linux Foundation. All rights reserved.
 * Copyright (c) 2014, Sony Mobile Communications AB.
 *
 */

#include <linux/acpi.h>
#include <linux/atomic.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/dmaengine.h>
#include <linux/dmapool.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/scatterlist.h>

/* QUP Registers */
#define QUP_CONFIG              0x000
#define QUP_STATE               0x004
#define QUP_IO_MODE             0x008
#define QUP_SW_RESET            0x00c
#define QUP_OPERATIONAL         0x018
#define QUP_ERROR_FLAGS         0x01c
#define QUP_ERROR_FLAGS_EN      0x020
#define QUP_OPERATIONAL_MASK    0x028
#define QUP_HW_VERSION          0x030
#define QUP_MX_OUTPUT_CNT       0x100
#define QUP_OUT_FIFO_BASE       0x110
#define QUP_MX_WRITE_CNT        0x150
#define QUP_MX_INPUT_CNT        0x200
#define QUP_MX_READ_CNT         0x208
#define QUP_IN_FIFO_BASE        0x218
#define QUP_I2C_CLK_CTL         0x400
#define QUP_I2C_STATUS          0x404
#define QUP_I2C_MASTER_GEN      0x408

/* QUP States and reset values */
#define QUP_RESET_STATE         0
#define QUP_RUN_STATE           1
#define QUP_PAUSE_STATE         3
#define QUP_STATE_MASK          3

#define QUP_STATE_VALID         BIT(2)
#define QUP_I2C_MAST_GEN        BIT(4)
#define QUP_I2C_FLUSH           BIT(6)

#define QUP_OPERATIONAL_RESET   0x000ff0
#define QUP_I2C_STATUS_RESET    0xfffffc

/* QUP OPERATIONAL FLAGS */
#define QUP_I2C_NACK_FLAG       BIT(3)
#define QUP_OUT_NOT_EMPTY       BIT(4)
#define QUP_IN_NOT_EMPTY        BIT(5)
#define QUP_OUT_FULL            BIT(6)
#define QUP_OUT_SVC_FLAG        BIT(8)
#define QUP_IN_SVC_FLAG         BIT(9)
#define QUP_MX_OUTPUT_DONE      BIT(10)
#define QUP_MX_INPUT_DONE       BIT(11)
#define OUT_BLOCK_WRITE_REQ     BIT(12)
#define IN_BLOCK_READ_REQ       BIT(13)

/* I2C mini core related values */
#define QUP_NO_INPUT            BIT(7)
#define QUP_CLOCK_AUTO_GATE     BIT(13)
#define I2C_MINI_CORE           (2 << 8)
#define I2C_N_VAL               15
#define I2C_N_VAL_V2            7

/* Most significant word offset in FIFO port */
#define QUP_MSW_SHIFT           (I2C_N_VAL + 1)

/* Packing/Unpacking words in FIFOs, and IO modes */
#define QUP_OUTPUT_BLK_MODE     (1 << 10)
#define QUP_OUTPUT_BAM_MODE     (3 << 10)
#define QUP_INPUT_BLK_MODE      (1 << 12)
#define QUP_INPUT_BAM_MODE      (3 << 12)
#define QUP_BAM_MODE            (QUP_OUTPUT_BAM_MODE | QUP_INPUT_BAM_MODE)
#define QUP_UNPACK_EN           BIT(14)
#define QUP_PACK_EN             BIT(15)

#define QUP_REPACK_EN           (QUP_UNPACK_EN | QUP_PACK_EN)
#define QUP_V2_TAGS_EN          1

#define QUP_OUTPUT_BLOCK_SIZE(x)(((x) >> 0) & 0x03)
#define QUP_OUTPUT_FIFO_SIZE(x) (((x) >> 2) & 0x07)
#define QUP_INPUT_BLOCK_SIZE(x) (((x) >> 5) & 0x03)
#define QUP_INPUT_FIFO_SIZE(x)  (((x) >> 7) & 0x07)

/* QUP tags */
#define QUP_TAG_START           (1 << 8)
#define QUP_TAG_DATA            (2 << 8)
#define QUP_TAG_STOP            (3 << 8)
#define QUP_TAG_REC             (4 << 8)
#define QUP_BAM_INPUT_EOT               0x93
#define QUP_BAM_FLUSH_STOP              0x96

/* QUP v2 tags */
#define QUP_TAG_V2_START               0x81
#define QUP_TAG_V2_DATAWR              0x82
#define QUP_TAG_V2_DATAWR_STOP         0x83
#define QUP_TAG_V2_DATARD              0x85
#define QUP_TAG_V2_DATARD_NACK         0x86
#define QUP_TAG_V2_DATARD_STOP         0x87

/* Status, Error flags */
#define I2C_STATUS_WR_BUFFER_FULL       BIT(0)
#define I2C_STATUS_BUS_ACTIVE           BIT(8)
#define I2C_STATUS_ERROR_MASK           0x38000fc
#define QUP_STATUS_ERROR_FLAGS          0x7c

#define QUP_READ_LIMIT                  256
#define SET_BIT                         0x1
#define RESET_BIT                       0x0
#define ONE_BYTE                        0x1
#define QUP_I2C_MX_CONFIG_DURING_RUN   BIT(31)

/* Maximum transfer length for single DMA descriptor */
#define MX_TX_RX_LEN                    SZ_64K
#define MX_BLOCKS                       (MX_TX_RX_LEN / QUP_READ_LIMIT)
/* Maximum transfer length for all DMA descriptors */
#define MX_DMA_TX_RX_LEN                (2 * MX_TX_RX_LEN)
#define MX_DMA_BLOCKS                   (MX_DMA_TX_RX_LEN / QUP_READ_LIMIT)

/*
 * Minimum transfer timeout for i2c transfers in seconds. It will be added on
 * the top of maximum transfer time calculated from i2c bus speed to compensate
 * the overheads.
 */
#define TOUT_MIN                        2

/* I2C Frequency Modes */
#define I2C_STANDARD_FREQ               100000
#define I2C_FAST_MODE_FREQ              400000
#define I2C_FAST_MODE_PLUS_FREQ         1000000

/* Default values. Use these if FW query fails */
#define DEFAULT_CLK_FREQ I2C_STANDARD_FREQ
#define DEFAULT_SRC_CLK 20000000

/*
 * Max tags length (start, stop and maximum 2 bytes address) for each QUP
 * data transfer
 */
#define QUP_MAX_TAGS_LEN                4
/* Max data length for each DATARD tags */
#define RECV_MAX_DATA_LEN               254
/* TAG length for DATA READ in RX FIFO  */
#define READ_RX_TAGS_LEN                2

static unsigned int scl_freq;
module_param_named(scl_freq, scl_freq, uint, 0444);
MODULE_PARM_DESC(scl_freq, "SCL frequency override");

/*
 * count: no of blocks
 * pos: current block number
 * tx_tag_len: tx tag length for current block
 * rx_tag_len: rx tag length for current block
 * data_len: remaining data length for current message
 * cur_blk_len: data length for current block
 * total_tx_len: total tx length including tag bytes for current QUP transfer
 * total_rx_len: total rx length including tag bytes for current QUP transfer
 * tx_fifo_data_pos: current byte number in TX FIFO word
 * tx_fifo_free: number of free bytes in current QUP block write.
 * rx_fifo_data_pos: current byte number in RX FIFO word
 * fifo_available: number of available bytes in RX FIFO for current
 *                 QUP block read
 * tx_fifo_data: QUP TX FIFO write works on word basis (4 bytes). New byte write
 *               to TX FIFO will be appended in this data and will be written to
 *               TX FIFO when all the 4 bytes are available.
 * rx_fifo_data: QUP RX FIFO read works on word basis (4 bytes). This will
 *               contains the 4 bytes of RX data.
 * cur_data: pointer to tell cur data position for current message
 * cur_tx_tags: pointer to tell cur position in tags
 * tx_tags_sent: all tx tag bytes have been written in FIFO word
 * send_last_word: for tx FIFO, last word send is pending in current block
 * rx_bytes_read: if all the bytes have been read from rx FIFO.
 * rx_tags_fetched: all the rx tag bytes have been fetched from rx fifo word
 * is_tx_blk_mode: whether tx uses block or FIFO mode in case of non BAM xfer.
 * is_rx_blk_mode: whether rx uses block or FIFO mode in case of non BAM xfer.
 * tags: contains tx tag bytes for current QUP transfer
 */
struct qup_i2c_block {
        int             count;
        int             pos;
        int             tx_tag_len;
        int             rx_tag_len;
        int             data_len;
        int             cur_blk_len;
        int             total_tx_len;
        int             total_rx_len;
        int             tx_fifo_data_pos;
        int             tx_fifo_free;
        int             rx_fifo_data_pos;
        int             fifo_available;
        u32             tx_fifo_data;
        u32             rx_fifo_data;
        u8              *cur_data;
        u8              *cur_tx_tags;
        bool            tx_tags_sent;
        bool            send_last_word;
        bool            rx_tags_fetched;
        bool            rx_bytes_read;
        bool            is_tx_blk_mode;
        bool            is_rx_blk_mode;
        u8              tags[6];
};

struct qup_i2c_tag {
        u8 *start;
        dma_addr_t addr;
};

struct qup_i2c_bam {
        struct  qup_i2c_tag tag;
        struct  dma_chan *dma;
        struct  scatterlist *sg;
        unsigned int sg_cnt;
};

struct qup_i2c_dev {
        struct device           *dev;
        void __iomem            *base;
        int                     irq;
        struct clk              *clk;
        struct clk              *pclk;
        struct i2c_adapter      adap;

        int                     clk_ctl;
        int                     out_fifo_sz;
        int                     in_fifo_sz;
        int                     out_blk_sz;
        int                     in_blk_sz;

        int                     blk_xfer_limit;
        unsigned long           one_byte_t;
        unsigned long           xfer_timeout;
        struct qup_i2c_block    blk;

        struct i2c_msg          *msg;
        /* Current posion in user message buffer */
        int                     pos;
        /* I2C protocol errors */
        u32                     bus_err;
        /* QUP core errors */
        u32                     qup_err;

        /* To check if this is the last msg */
        bool                    is_last;
        bool                    is_smbus_read;

        /* To configure when bus is in run state */
        u32                     config_run;

        /* dma parameters */
        bool                    is_dma;
        /* To check if the current transfer is using DMA */
        bool                    use_dma;
        unsigned int            max_xfer_sg_len;
        unsigned int            tag_buf_pos;
        /* The threshold length above which block mode will be used */
        unsigned int            blk_mode_threshold;
        struct                  dma_pool *dpool;
        struct                  qup_i2c_tag start_tag;
        struct                  qup_i2c_bam brx;
        struct                  qup_i2c_bam btx;

        struct completion       xfer;
        /* function to write data in tx fifo */
        void (*write_tx_fifo)(struct qup_i2c_dev *qup);
        /* function to read data from rx fifo */
        void (*read_rx_fifo)(struct qup_i2c_dev *qup);
        /* function to write tags in tx fifo for i2c read transfer */
        void (*write_rx_tags)(struct qup_i2c_dev *qup);
};

static irqreturn_t qup_i2c_interrupt(int irq, void *dev)
{
        struct qup_i2c_dev *qup = dev;
        struct qup_i2c_block *blk = &qup->blk;
        u32 bus_err;
        u32 qup_err;
        u32 opflags;

        bus_err = readl(qup->base + QUP_I2C_STATUS);
        qup_err = readl(qup->base + QUP_ERROR_FLAGS);
        opflags = readl(qup->base + QUP_OPERATIONAL);

        if (!qup->msg) {
                /* Clear Error interrupt */
                writel(QUP_RESET_STATE, qup->base + QUP_STATE);
                return IRQ_HANDLED;
        }

        bus_err &= I2C_STATUS_ERROR_MASK;
        qup_err &= QUP_STATUS_ERROR_FLAGS;

        /* Clear the error bits in QUP_ERROR_FLAGS */
        if (qup_err)
                writel(qup_err, qup->base + QUP_ERROR_FLAGS);

        /* Clear the error bits in QUP_I2C_STATUS */
        if (bus_err)
                writel(bus_err, qup->base + QUP_I2C_STATUS);

        /*
         * Check for BAM mode and returns if already error has come for current
         * transfer. In Error case, sometimes, QUP generates more than one
         * interrupt.
         */
        if (qup->use_dma && (qup->qup_err || qup->bus_err))
                return IRQ_HANDLED;

        /* Reset the QUP State in case of error */
        if (qup_err || bus_err) {
                /*
                 * Don’t reset the QUP state in case of BAM mode. The BAM
                 * flush operation needs to be scheduled in transfer function
                 * which will clear the remaining schedule descriptors in BAM
                 * HW FIFO and generates the BAM interrupt.
                 */
                if (!qup->use_dma)
                        writel(QUP_RESET_STATE, qup->base + QUP_STATE);
                goto done;
        }

        if (opflags & QUP_OUT_SVC_FLAG) {
                writel(QUP_OUT_SVC_FLAG, qup->base + QUP_OPERATIONAL);

                if (opflags & OUT_BLOCK_WRITE_REQ) {
                        blk->tx_fifo_free += qup->out_blk_sz;
                        if (qup->msg->flags & I2C_M_RD)
                                qup->write_rx_tags(qup);
                        else
                                qup->write_tx_fifo(qup);
                }
        }

        if (opflags & QUP_IN_SVC_FLAG) {
                writel(QUP_IN_SVC_FLAG, qup->base + QUP_OPERATIONAL);

                if (!blk->is_rx_blk_mode) {
                        blk->fifo_available += qup->in_fifo_sz;
                        qup->read_rx_fifo(qup);
                } else if (opflags & IN_BLOCK_READ_REQ) {
                        blk->fifo_available += qup->in_blk_sz;
                        qup->read_rx_fifo(qup);
                }
        }

        if (qup->msg->flags & I2C_M_RD) {
                if (!blk->rx_bytes_read)
                        return IRQ_HANDLED;
        } else {
                /*
                 * Ideally, QUP_MAX_OUTPUT_DONE_FLAG should be checked
                 * for FIFO mode also. But, QUP_MAX_OUTPUT_DONE_FLAG lags
                 * behind QUP_OUTPUT_SERVICE_FLAG sometimes. The only reason
                 * of interrupt for write message in FIFO mode is
                 * QUP_MAX_OUTPUT_DONE_FLAG condition.
                 */
                if (blk->is_tx_blk_mode && !(opflags & QUP_MX_OUTPUT_DONE))
                        return IRQ_HANDLED;
        }

done:
        qup->qup_err = qup_err;
        qup->bus_err = bus_err;
        complete(&qup->xfer);
        return IRQ_HANDLED;
}

static int qup_i2c_poll_state_mask(struct qup_i2c_dev *qup,
                                   u32 req_state, u32 req_mask)
{
        int retries = 1;
        u32 state;

        /*
         * State transition takes 3 AHB clocks cycles + 3 I2C master clock
         * cycles. So retry once after a 1uS delay.
         */
        do {
                state = readl(qup->base + QUP_STATE);

                if (state & QUP_STATE_VALID &&
                    (state & req_mask) == req_state)
                        return 0;

                udelay(1);
        } while (retries--);

        return -ETIMEDOUT;
}

static int qup_i2c_poll_state(struct qup_i2c_dev *qup, u32 req_state)
{
        return qup_i2c_poll_state_mask(qup, req_state, QUP_STATE_MASK);
}

static void qup_i2c_flush(struct qup_i2c_dev *qup)
{
        u32 val = readl(qup->base + QUP_STATE);

        val |= QUP_I2C_FLUSH;
        writel(val, qup->base + QUP_STATE);
}

static int qup_i2c_poll_state_valid(struct qup_i2c_dev *qup)
{
        return qup_i2c_poll_state_mask(qup, 0, 0);
}

static int qup_i2c_poll_state_i2c_master(struct qup_i2c_dev *qup)
{
        return qup_i2c_poll_state_mask(qup, QUP_I2C_MAST_GEN, QUP_I2C_MAST_GEN);
}

static int qup_i2c_change_state(struct qup_i2c_dev *qup, u32 state)
{
        if (qup_i2c_poll_state_valid(qup) != 0)
                return -EIO;

        writel(state, qup->base + QUP_STATE);

        if (qup_i2c_poll_state(qup, state) != 0)
                return -EIO;
        return 0;
}

/* Check if I2C bus returns to IDLE state */
static int qup_i2c_bus_active(struct qup_i2c_dev *qup, int len)
{
        unsigned long timeout;
        u32 status;
        int ret = 0;

        timeout = jiffies + len * 4;
        for (;;) {
                status = readl(qup->base + QUP_I2C_STATUS);
                if (!(status & I2C_STATUS_BUS_ACTIVE))
                        break;

                if (time_after(jiffies, timeout))
                        ret = -ETIMEDOUT;

                usleep_range(len, len * 2);
        }

        return ret;
}

static void qup_i2c_write_tx_fifo_v1(struct qup_i2c_dev *qup)
{
        struct qup_i2c_block *blk = &qup->blk;
        struct i2c_msg *msg = qup->msg;
        u32 addr = i2c_8bit_addr_from_msg(msg);
        u32 qup_tag;
        int idx;
        u32 val;

        if (qup->pos == 0) {
                val = QUP_TAG_START | addr;
                idx = 1;
                blk->tx_fifo_free--;
        } else {
                val = 0;
                idx = 0;
        }

        while (blk->tx_fifo_free && qup->pos < msg->len) {
                if (qup->pos == msg->len - 1)
                        qup_tag = QUP_TAG_STOP;
                else
                        qup_tag = QUP_TAG_DATA;

                if (idx & 1)
                        val |= (qup_tag | msg->buf[qup->pos]) << QUP_MSW_SHIFT;
                else
                        val = qup_tag | msg->buf[qup->pos];

                /* Write out the pair and the last odd value */
                if (idx & 1 || qup->pos == msg->len - 1)
                        writel(val, qup->base + QUP_OUT_FIFO_BASE);

                qup->pos++;
                idx++;
                blk->tx_fifo_free--;
        }
}

static void qup_i2c_set_blk_data(struct qup_i2c_dev *qup,
                                 struct i2c_msg *msg)
{
        qup->blk.pos = 0;
        qup->blk.data_len = msg->len;
        qup->blk.count = DIV_ROUND_UP(msg->len, qup->blk_xfer_limit);
}

static int qup_i2c_get_data_len(struct qup_i2c_dev *qup)
{
        int data_len;

        if (qup->blk.data_len > qup->blk_xfer_limit)
                data_len = qup->blk_xfer_limit;
        else
                data_len = qup->blk.data_len;

        return data_len;
}

static bool qup_i2c_check_msg_len(struct i2c_msg *msg)
{
        return ((msg->flags & I2C_M_RD) && (msg->flags & I2C_M_RECV_LEN));
}

static int qup_i2c_set_tags_smb(u16 addr, u8 *tags, struct qup_i2c_dev *qup,
                        struct i2c_msg *msg)
{
        int len = 0;

        if (qup->is_smbus_read) {
                tags[len++] = QUP_TAG_V2_DATARD_STOP;
                tags[len++] = qup_i2c_get_data_len(qup);
        } else {
                tags[len++] = QUP_TAG_V2_START;
                tags[len++] = addr & 0xff;

                if (msg->flags & I2C_M_TEN)
                        tags[len++] = addr >> 8;

                tags[len++] = QUP_TAG_V2_DATARD;
                /* Read 1 byte indicating the length of the SMBus message */
                tags[len++] = 1;
        }
        return len;
}

static int qup_i2c_set_tags(u8 *tags, struct qup_i2c_dev *qup,
                            struct i2c_msg *msg)
{
        u16 addr = i2c_8bit_addr_from_msg(msg);
        int len = 0;
        int data_len;

        int last = (qup->blk.pos == (qup->blk.count - 1)) && (qup->is_last);

        /* Handle tags for SMBus block read */
        if (qup_i2c_check_msg_len(msg))
                return qup_i2c_set_tags_smb(addr, tags, qup, msg);

        if (qup->blk.pos == 0) {
                tags[len++] = QUP_TAG_V2_START;
                tags[len++] = addr & 0xff;

                if (msg->flags & I2C_M_TEN)
                        tags[len++] = addr >> 8;
        }

        /* Send _STOP commands for the last block */
        if (last) {
                if (msg->flags & I2C_M_RD)
                        tags[len++] = QUP_TAG_V2_DATARD_STOP;
                else
                        tags[len++] = QUP_TAG_V2_DATAWR_STOP;
        } else {
                if (msg->flags & I2C_M_RD)
                        tags[len++] = qup->blk.pos == (qup->blk.count - 1) ?
                                      QUP_TAG_V2_DATARD_NACK :
                                      QUP_TAG_V2_DATARD;
                else
                        tags[len++] = QUP_TAG_V2_DATAWR;
        }

        data_len = qup_i2c_get_data_len(qup);

        /* 0 implies 256 bytes */
        if (data_len == QUP_READ_LIMIT)
                tags[len++] = 0;
        else
                tags[len++] = data_len;

        return len;
}


static void qup_i2c_bam_cb(void *data)
{
        struct qup_i2c_dev *qup = data;

        complete(&qup->xfer);
}

static int qup_sg_set_buf(struct scatterlist *sg, void *buf,
                          unsigned int buflen, struct qup_i2c_dev *qup,
                          int dir)
{
        int ret;

        sg_set_buf(sg, buf, buflen);
        ret = dma_map_sg(qup->dev, sg, 1, dir);
        if (!ret)
                return -EINVAL;

        return 0;
}

static void qup_i2c_rel_dma(struct qup_i2c_dev *qup)
{
        if (qup->btx.dma)
                dma_release_channel(qup->btx.dma);
        if (qup->brx.dma)
                dma_release_channel(qup->brx.dma);
        qup->btx.dma = NULL;
        qup->brx.dma = NULL;
}

static int qup_i2c_req_dma(struct qup_i2c_dev *qup)
{
        int err;

        if (!qup->btx.dma) {
                qup->btx.dma = dma_request_chan(qup->dev, "tx");
                if (IS_ERR(qup->btx.dma)) {
                        err = PTR_ERR(qup->btx.dma);
                        qup->btx.dma = NULL;
                        dev_err(qup->dev, "\n tx channel not available");
                        return err;
                }
        }

        if (!qup->brx.dma) {
                qup->brx.dma = dma_request_chan(qup->dev, "rx");
                if (IS_ERR(qup->brx.dma)) {
                        dev_err(qup->dev, "\n rx channel not available");
                        err = PTR_ERR(qup->brx.dma);
                        qup->brx.dma = NULL;
                        qup_i2c_rel_dma(qup);
                        return err;
                }
        }
        return 0;
}

static int qup_i2c_bam_make_desc(struct qup_i2c_dev *qup, struct i2c_msg *msg)
{
        int ret = 0, limit = QUP_READ_LIMIT;
        u32 len = 0, blocks, rem;
        u32 i = 0, tlen, tx_len = 0;
        u8 *tags;

        qup->blk_xfer_limit = QUP_READ_LIMIT;
        qup_i2c_set_blk_data(qup, msg);

        blocks = qup->blk.count;
        rem = msg->len - (blocks - 1) * limit;

        if (msg->flags & I2C_M_RD) {
                while (qup->blk.pos < blocks) {
                        tlen = (i == (blocks - 1)) ? rem : limit;
                        tags = &qup->start_tag.start[qup->tag_buf_pos + len];
                        len += qup_i2c_set_tags(tags, qup, msg);
                        qup->blk.data_len -= tlen;

                        /* scratch buf to read the start and len tags */
                        ret = qup_sg_set_buf(&qup->brx.sg[qup->brx.sg_cnt++],
                                             &qup->brx.tag.start[0],
                                             2, qup, DMA_FROM_DEVICE);

                        if (ret)
                                return ret;

                        ret = qup_sg_set_buf(&qup->brx.sg[qup->brx.sg_cnt++],
                                             &msg->buf[limit * i],
                                             tlen, qup,
                                             DMA_FROM_DEVICE);
                        if (ret)
                                return ret;

                        i++;
                        qup->blk.pos = i;
                }
                ret = qup_sg_set_buf(&qup->btx.sg[qup->btx.sg_cnt++],
                                     &qup->start_tag.start[qup->tag_buf_pos],
                                     len, qup, DMA_TO_DEVICE);
                if (ret)
                        return ret;

                qup->tag_buf_pos += len;
        } else {
                while (qup->blk.pos < blocks) {
                        tlen = (i == (blocks - 1)) ? rem : limit;
                        tags = &qup->start_tag.start[qup->tag_buf_pos + tx_len];
                        len = qup_i2c_set_tags(tags, qup, msg);
                        qup->blk.data_len -= tlen;

                        ret = qup_sg_set_buf(&qup->btx.sg[qup->btx.sg_cnt++],
                                             tags, len,
                                             qup, DMA_TO_DEVICE);
                        if (ret)
                                return ret;

                        tx_len += len;
                        ret = qup_sg_set_buf(&qup->btx.sg[qup->btx.sg_cnt++],
                                             &msg->buf[limit * i],
                                             tlen, qup, DMA_TO_DEVICE);
                        if (ret)
                                return ret;
                        i++;
                        qup->blk.pos = i;
                }

                qup->tag_buf_pos += tx_len;
        }

        return 0;
}

static int qup_i2c_bam_schedule_desc(struct qup_i2c_dev *qup)
{
        struct dma_async_tx_descriptor *txd, *rxd = NULL;
        int ret = 0;
        dma_cookie_t cookie_rx, cookie_tx;
        u32 len = 0;
        u32 tx_cnt = qup->btx.sg_cnt, rx_cnt = qup->brx.sg_cnt;

        /* schedule the EOT and FLUSH I2C tags */
        len = 1;
        if (rx_cnt) {
                qup->btx.tag.start[0] = QUP_BAM_INPUT_EOT;
                len++;

                /* scratch buf to read the BAM EOT FLUSH tags */
                ret = qup_sg_set_buf(&qup->brx.sg[rx_cnt++],
                                     &qup->brx.tag.start[0],
                                     1, qup, DMA_FROM_DEVICE);
                if (ret)
                        return ret;
        }

        qup->btx.tag.start[len - 1] = QUP_BAM_FLUSH_STOP;
        ret = qup_sg_set_buf(&qup->btx.sg[tx_cnt++], &qup->btx.tag.start[0],
                             len, qup, DMA_TO_DEVICE);
        if (ret)
                return ret;

        txd = dmaengine_prep_slave_sg(qup->btx.dma, qup->btx.sg, tx_cnt,
                                      DMA_MEM_TO_DEV,
                                      DMA_PREP_INTERRUPT | DMA_PREP_FENCE);
        if (!txd) {
                dev_err(qup->dev, "failed to get tx desc\n");
                ret = -EINVAL;
                goto desc_err;
        }

        if (!rx_cnt) {
                txd->callback = qup_i2c_bam_cb;
                txd->callback_param = qup;
        }

        cookie_tx = dmaengine_submit(txd);
        if (dma_submit_error(cookie_tx)) {
                ret = -EINVAL;
                goto desc_err;
        }

        dma_async_issue_pending(qup->btx.dma);

        if (rx_cnt) {
                rxd = dmaengine_prep_slave_sg(qup->brx.dma, qup->brx.sg,
                                              rx_cnt, DMA_DEV_TO_MEM,
                                              DMA_PREP_INTERRUPT);
                if (!rxd) {
                        dev_err(qup->dev, "failed to get rx desc\n");
                        ret = -EINVAL;

                        /* abort TX descriptors */
                        dmaengine_terminate_all(qup->btx.dma);
                        goto desc_err;
                }

                rxd->callback = qup_i2c_bam_cb;
                rxd->callback_param = qup;
                cookie_rx = dmaengine_submit(rxd);
                if (dma_submit_error(cookie_rx)) {
                        ret = -EINVAL;
                        goto desc_err;
                }

                dma_async_issue_pending(qup->brx.dma);
        }

        if (!wait_for_completion_timeout(&qup->xfer, qup->xfer_timeout)) {
                dev_err(qup->dev, "normal trans timed out\n");
                ret = -ETIMEDOUT;
        }

        if (ret || qup->bus_err || qup->qup_err) {
                reinit_completion(&qup->xfer);

                if (qup_i2c_change_state(qup, QUP_RUN_STATE)) {
                        dev_err(qup->dev, "change to run state timed out");
                        goto desc_err;
                }

                qup_i2c_flush(qup);

                /* wait for remaining interrupts to occur */
                if (!wait_for_completion_timeout(&qup->xfer, HZ))
                        dev_err(qup->dev, "flush timed out\n");

                ret =  (qup->bus_err & QUP_I2C_NACK_FLAG) ? -ENXIO : -EIO;
        }

desc_err:
        dma_unmap_sg(qup->dev, qup->btx.sg, tx_cnt, DMA_TO_DEVICE);

        if (rx_cnt)
                dma_unmap_sg(qup->dev, qup->brx.sg, rx_cnt,
                             DMA_FROM_DEVICE);

        return ret;
}

static void qup_i2c_bam_clear_tag_buffers(struct qup_i2c_dev *qup)
{
        qup->btx.sg_cnt = 0;
        qup->brx.sg_cnt = 0;
        qup->tag_buf_pos = 0;
}

static int qup_i2c_bam_xfer(struct i2c_adapter *adap, struct i2c_msg *msg,
                            int num)
{
        struct qup_i2c_dev *qup = i2c_get_adapdata(adap);
        int ret = 0;
        int idx = 0;

        enable_irq(qup->irq);
        ret = qup_i2c_req_dma(qup);

        if (ret)
                goto out;

        writel(0, qup->base + QUP_MX_INPUT_CNT);
        writel(0, qup->base + QUP_MX_OUTPUT_CNT);

        /* set BAM mode */
        writel(QUP_REPACK_EN | QUP_BAM_MODE, qup->base + QUP_IO_MODE);

        /* mask fifo irqs */
        writel((0x3 << 8), qup->base + QUP_OPERATIONAL_MASK);

        /* set RUN STATE */
        ret = qup_i2c_change_state(qup, QUP_RUN_STATE);
        if (ret)
                goto out;

        writel(qup->clk_ctl, qup->base + QUP_I2C_CLK_CTL);
        qup_i2c_bam_clear_tag_buffers(qup);

        for (idx = 0; idx < num; idx++) {
                qup->msg = msg + idx;
                qup->is_last = idx == (num - 1);

                ret = qup_i2c_bam_make_desc(qup, qup->msg);
                if (ret)
                        break;

                /*
                 * Make DMA descriptor and schedule the BAM transfer if its
                 * already crossed the maximum length. Since the memory for all
                 * tags buffers have been taken for 2 maximum possible
                 * transfers length so it will never cross the buffer actual
                 * length.
                 */
                if (qup->btx.sg_cnt > qup->max_xfer_sg_len ||
                    qup->brx.sg_cnt > qup->max_xfer_sg_len ||
                    qup->is_last) {
                        ret = qup_i2c_bam_schedule_desc(qup);
                        if (ret)
                                break;

                        qup_i2c_bam_clear_tag_buffers(qup);
                }
        }

out:
        disable_irq(qup->irq);

        qup->msg = NULL;
        return ret;
}

static int qup_i2c_wait_for_complete(struct qup_i2c_dev *qup,
                                     struct i2c_msg *msg)
{
        unsigned long left;
        int ret = 0;

        left = wait_for_completion_timeout(&qup->xfer, qup->xfer_timeout);
        if (!left) {
                writel(1, qup->base + QUP_SW_RESET);
                ret = -ETIMEDOUT;
        }

        if (qup->bus_err || qup->qup_err)
                ret =  (qup->bus_err & QUP_I2C_NACK_FLAG) ? -ENXIO : -EIO;

        return ret;
}

static void qup_i2c_read_rx_fifo_v1(struct qup_i2c_dev *qup)
{
        struct qup_i2c_block *blk = &qup->blk;
        struct i2c_msg *msg = qup->msg;
        u32 val = 0;
        int idx = 0;

        while (blk->fifo_available && qup->pos < msg->len) {
                if ((idx & 1) == 0) {
                        /* Reading 2 words at time */
                        val = readl(qup->base + QUP_IN_FIFO_BASE);
                        msg->buf[qup->pos++] = val & 0xFF;
                } else {
                        msg->buf[qup->pos++] = val >> QUP_MSW_SHIFT;
                }
                idx++;
                blk->fifo_available--;
        }

        if (qup->pos == msg->len)
                blk->rx_bytes_read = true;
}

static void qup_i2c_write_rx_tags_v1(struct qup_i2c_dev *qup)
{
        struct i2c_msg *msg = qup->msg;
        u32 addr, len, val;

        addr = i2c_8bit_addr_from_msg(msg);

        /* 0 is used to specify a length 256 (QUP_READ_LIMIT) */
        len = (msg->len == QUP_READ_LIMIT) ? 0 : msg->len;

        val = ((QUP_TAG_REC | len) << QUP_MSW_SHIFT) | QUP_TAG_START | addr;
        writel(val, qup->base + QUP_OUT_FIFO_BASE);
}

static void qup_i2c_conf_v1(struct qup_i2c_dev *qup)
{
        struct qup_i2c_block *blk = &qup->blk;
        u32 qup_config = I2C_MINI_CORE | I2C_N_VAL;
        u32 io_mode = QUP_REPACK_EN;

        blk->is_tx_blk_mode =
                blk->total_tx_len > qup->out_fifo_sz ? true : false;
        blk->is_rx_blk_mode =
                blk->total_rx_len > qup->in_fifo_sz ? true : false;

        if (blk->is_tx_blk_mode) {
                io_mode |= QUP_OUTPUT_BLK_MODE;
                writel(0, qup->base + QUP_MX_WRITE_CNT);
                writel(blk->total_tx_len, qup->base + QUP_MX_OUTPUT_CNT);
        } else {
                writel(0, qup->base + QUP_MX_OUTPUT_CNT);
                writel(blk->total_tx_len, qup->base + QUP_MX_WRITE_CNT);
        }

        if (blk->total_rx_len) {
                if (blk->is_rx_blk_mode) {
                        io_mode |= QUP_INPUT_BLK_MODE;
                        writel(0, qup->base + QUP_MX_READ_CNT);
                        writel(blk->total_rx_len, qup->base + QUP_MX_INPUT_CNT);
                } else {
                        writel(0, qup->base + QUP_MX_INPUT_CNT);
                        writel(blk->total_rx_len, qup->base + QUP_MX_READ_CNT);
                }
        } else {
                qup_config |= QUP_NO_INPUT;
        }

        writel(qup_config, qup->base + QUP_CONFIG);
        writel(io_mode, qup->base + QUP_IO_MODE);
}

static void qup_i2c_clear_blk_v1(struct qup_i2c_block *blk)
{
        blk->tx_fifo_free = 0;
        blk->fifo_available = 0;
        blk->rx_bytes_read = false;
}

static int qup_i2c_conf_xfer_v1(struct qup_i2c_dev *qup, bool is_rx)
{
        struct qup_i2c_block *blk = &qup->blk;
        int ret;

        qup_i2c_clear_blk_v1(blk);
        qup_i2c_conf_v1(qup);
        ret = qup_i2c_change_state(qup, QUP_RUN_STATE);
        if (ret)
                return ret;

        writel(qup->clk_ctl, qup->base + QUP_I2C_CLK_CTL);

        ret = qup_i2c_change_state(qup, QUP_PAUSE_STATE);
        if (ret)
                return ret;

        reinit_completion(&qup->xfer);
        enable_irq(qup->irq);
        if (!blk->is_tx_blk_mode) {
                blk->tx_fifo_free = qup->out_fifo_sz;

                if (is_rx)
                        qup_i2c_write_rx_tags_v1(qup);
                else
                        qup_i2c_write_tx_fifo_v1(qup);
        }

        ret = qup_i2c_change_state(qup, QUP_RUN_STATE);
        if (ret)
                goto err;

        ret = qup_i2c_wait_for_complete(qup, qup->msg);
        if (ret)
                goto err;

        ret = qup_i2c_bus_active(qup, ONE_BYTE);

err:
        disable_irq(qup->irq);
        return ret;
}

static int qup_i2c_write_one(struct qup_i2c_dev *qup)
{
        struct i2c_msg *msg = qup->msg;
        struct qup_i2c_block *blk = &qup->blk;

        qup->pos = 0;
        blk->total_tx_len = msg->len + 1;
        blk->total_rx_len = 0;

        return qup_i2c_conf_xfer_v1(qup, false);
}

static int qup_i2c_read_one(struct qup_i2c_dev *qup)
{
        struct qup_i2c_block *blk = &qup->blk;

        qup->pos = 0;
        blk->total_tx_len = 2;
        blk->total_rx_len = qup->msg->len;

        return qup_i2c_conf_xfer_v1(qup, true);
}

static int qup_i2c_xfer(struct i2c_adapter *adap,
                        struct i2c_msg msgs[],
                        int num)
{
        struct qup_i2c_dev *qup = i2c_get_adapdata(adap);
        int ret, idx;

        ret = pm_runtime_get_sync(qup->dev);
        if (ret < 0)
                goto out;

        qup->bus_err = 0;
        qup->qup_err = 0;

        writel(1, qup->base + QUP_SW_RESET);
        ret = qup_i2c_poll_state(qup, QUP_RESET_STATE);
        if (ret)
                goto out;

        /* Configure QUP as I2C mini core */
        writel(I2C_MINI_CORE | I2C_N_VAL, qup->base + QUP_CONFIG);

        for (idx = 0; idx < num; idx++) {
                if (qup_i2c_poll_state_i2c_master(qup)) {
                        ret = -EIO;
                        goto out;
                }

                if (qup_i2c_check_msg_len(&msgs[idx])) {
                        ret = -EINVAL;
                        goto out;
                }

                qup->msg = &msgs[idx];
                if (msgs[idx].flags & I2C_M_RD)
                        ret = qup_i2c_read_one(qup);
                else
                        ret = qup_i2c_write_one(qup);

                if (ret)
                        break;

                ret = qup_i2c_change_state(qup, QUP_RESET_STATE);
                if (ret)
                        break;
        }

        if (ret == 0)
                ret = num;
out:

        pm_runtime_mark_last_busy(qup->dev);
        pm_runtime_put_autosuspend(qup->dev);

        return ret;
}

/*
 * Configure registers related with reconfiguration during run and call it
 * before each i2c sub transfer.
 */
static void qup_i2c_conf_count_v2(struct qup_i2c_dev *qup)
{
        struct qup_i2c_block *blk = &qup->blk;
        u32 qup_config = I2C_MINI_CORE | I2C_N_VAL_V2;

        if (blk->is_tx_blk_mode)
                writel(qup->config_run | blk->total_tx_len,
                       qup->base + QUP_MX_OUTPUT_CNT);
        else
                writel(qup->config_run | blk->total_tx_len,
                       qup->base + QUP_MX_WRITE_CNT);

        if (blk->total_rx_len) {
                if (blk->is_rx_blk_mode)
                        writel(qup->config_run | blk->total_rx_len,
                               qup->base + QUP_MX_INPUT_CNT);
                else
                        writel(qup->config_run | blk->total_rx_len,
                               qup->base + QUP_MX_READ_CNT);
        } else {
                qup_config |= QUP_NO_INPUT;
        }

        writel(qup_config, qup->base + QUP_CONFIG);
}

/*
 * Configure registers related with transfer mode (FIFO/Block)
 * before starting of i2c transfer. It will be called only once in
 * QUP RESET state.
 */
static void qup_i2c_conf_mode_v2(struct qup_i2c_dev *qup)
{
        struct qup_i2c_block *blk = &qup->blk;
        u32 io_mode = QUP_REPACK_EN;

        if (blk->is_tx_blk_mode) {
                io_mode |= QUP_OUTPUT_BLK_MODE;
                writel(0, qup->base + QUP_MX_WRITE_CNT);
        } else {
                writel(0, qup->base + QUP_MX_OUTPUT_CNT);
        }

        if (blk->is_rx_blk_mode) {
                io_mode |= QUP_INPUT_BLK_MODE;
                writel(0, qup->base + QUP_MX_READ_CNT);
        } else {
                writel(0, qup->base + QUP_MX_INPUT_CNT);
        }

        writel(io_mode, qup->base + QUP_IO_MODE);
}

/* Clear required variables before starting of any QUP v2 sub transfer. */
static void qup_i2c_clear_blk_v2(struct qup_i2c_block *blk)
{
        blk->send_last_word = false;
        blk->tx_tags_sent = false;
        blk->tx_fifo_data = 0;
        blk->tx_fifo_data_pos = 0;
        blk->tx_fifo_free = 0;

        blk->rx_tags_fetched = false;
        blk->rx_bytes_read = false;
        blk->rx_fifo_data = 0;
        blk->rx_fifo_data_pos = 0;
        blk->fifo_available = 0;
}

/* Receive data from RX FIFO for read message in QUP v2 i2c transfer. */
static void qup_i2c_recv_data(struct qup_i2c_dev *qup)
{
        struct qup_i2c_block *blk = &qup->blk;
        int j;

        for (j = blk->rx_fifo_data_pos;
             blk->cur_blk_len && blk->fifo_available;
             blk->cur_blk_len--, blk->fifo_available--) {
                if (j == 0)
                        blk->rx_fifo_data = readl(qup->base + QUP_IN_FIFO_BASE);

                *(blk->cur_data++) = blk->rx_fifo_data;
                blk->rx_fifo_data >>= 8;

                if (j == 3)
                        j = 0;
                else
                        j++;
        }

        blk->rx_fifo_data_pos = j;
}

/* Receive tags for read message in QUP v2 i2c transfer. */
static void qup_i2c_recv_tags(struct qup_i2c_dev *qup)
{
        struct qup_i2c_block *blk = &qup->blk;

        blk->rx_fifo_data = readl(qup->base + QUP_IN_FIFO_BASE);
        blk->rx_fifo_data >>= blk->rx_tag_len  * 8;
        blk->rx_fifo_data_pos = blk->rx_tag_len;
        blk->fifo_available -= blk->rx_tag_len;
}

/*
 * Read the data and tags from RX FIFO. Since in read case, the tags will be
 * preceded by received data bytes so
 * 1. Check if rx_tags_fetched is false i.e. the start of QUP block so receive
 *    all tag bytes and discard that.
 * 2. Read the data from RX FIFO. When all the data bytes have been read then
 *    set rx_bytes_read to true.
 */
static void qup_i2c_read_rx_fifo_v2(struct qup_i2c_dev *qup)
{
        struct qup_i2c_block *blk = &qup->blk;

        if (!blk->rx_tags_fetched) {
                qup_i2c_recv_tags(qup);
                blk->rx_tags_fetched = true;
        }

        qup_i2c_recv_data(qup);
        if (!blk->cur_blk_len)
                blk->rx_bytes_read = true;
}

/*
 * Write bytes in TX FIFO for write message in QUP v2 i2c transfer. QUP TX FIFO
 * write works on word basis (4 bytes). Append new data byte write for TX FIFO
 * in tx_fifo_data and write to TX FIFO when all the 4 bytes are present.
 */
static void
qup_i2c_write_blk_data(struct qup_i2c_dev *qup, u8 **data, unsigned int *len)
{
        struct qup_i2c_block *blk = &qup->blk;
        unsigned int j;

        for (j = blk->tx_fifo_data_pos; *len && blk->tx_fifo_free;
             (*len)--, blk->tx_fifo_free--) {
                blk->tx_fifo_data |= *(*data)++ << (j * 8);
                if (j == 3) {
                        writel(blk->tx_fifo_data,
                               qup->base + QUP_OUT_FIFO_BASE);
                        blk->tx_fifo_data = 0x0;
                        j = 0;
                } else {
                        j++;
                }
        }

        blk->tx_fifo_data_pos = j;
}

/* Transfer tags for read message in QUP v2 i2c transfer. */
static void qup_i2c_write_rx_tags_v2(struct qup_i2c_dev *qup)
{
        struct qup_i2c_block *blk = &qup->blk;

        qup_i2c_write_blk_data(qup, &blk->cur_tx_tags, &blk->tx_tag_len);
        if (blk->tx_fifo_data_pos)
                writel(blk->tx_fifo_data, qup->base + QUP_OUT_FIFO_BASE);
}

/*
 * Write the data and tags in TX FIFO. Since in write case, both tags and data
 * need to be written and QUP write tags can have maximum 256 data length, so
 *
 * 1. Check if tx_tags_sent is false i.e. the start of QUP block so write the
 *    tags to TX FIFO and set tx_tags_sent to true.
 * 2. Check if send_last_word is true. It will be set when last few data bytes
 *    (less than 4 bytes) are reamining to be written in FIFO because of no FIFO
 *    space. All this data bytes are available in tx_fifo_data so write this
 *    in FIFO.
 * 3. Write the data to TX FIFO and check for cur_blk_len. If it is non zero
 *    then more data is pending otherwise following 3 cases can be possible
 *    a. if tx_fifo_data_pos is zero i.e. all the data bytes in this block
 *       have been written in TX FIFO so nothing else is required.
 *    b. tx_fifo_free is non zero i.e tx FIFO is free so copy the remaining data
 *       from tx_fifo_data to tx FIFO. Since, qup_i2c_write_blk_data do write
 *       in 4 bytes and FIFO space is in multiple of 4 bytes so tx_fifo_free
 *       will be always greater than or equal to 4 bytes.
 *    c. tx_fifo_free is zero. In this case, last few bytes (less than 4
 *       bytes) are copied to tx_fifo_data but couldn't be sent because of
 *       FIFO full so make send_last_word true.
 */
static void qup_i2c_write_tx_fifo_v2(struct qup_i2c_dev *qup)
{
        struct qup_i2c_block *blk = &qup->blk;

        if (!blk->tx_tags_sent) {
                qup_i2c_write_blk_data(qup, &blk->cur_tx_tags,
                                       &blk->tx_tag_len);
                blk->tx_tags_sent = true;
        }

        if (blk->send_last_word)
                goto send_last_word;

        qup_i2c_write_blk_data(qup, &blk->cur_data, &blk->cur_blk_len);
        if (!blk->cur_blk_len) {
                if (!blk->tx_fifo_data_pos)
                        return;

                if (blk->tx_fifo_free)
                        goto send_last_word;

                blk->send_last_word = true;
        }

        return;

send_last_word:
        writel(blk->tx_fifo_data, qup->base + QUP_OUT_FIFO_BASE);
}

/*
 * Main transfer function which read or write i2c data.
 * The QUP v2 supports reconfiguration during run in which multiple i2c sub
 * transfers can be scheduled.
 */
static int
qup_i2c_conf_xfer_v2(struct qup_i2c_dev *qup, bool is_rx, bool is_first,
                     bool change_pause_state)
{
        struct qup_i2c_block *blk = &qup->blk;
        struct i2c_msg *msg = qup->msg;
        int ret;

        /*
         * Check if its SMBus Block read for which the top level read will be
         * done into 2 QUP reads. One with message length 1 while other one is
         * with actual length.
         */
        if (qup_i2c_check_msg_len(msg)) {
                if (qup->is_smbus_read) {
                        /*
                         * If the message length is already read in
                         * the first byte of the buffer, account for
                         * that by setting the offset
                         */
                        blk->cur_data += 1;
                        is_first = false;
                } else {
                        change_pause_state = false;
                }
        }

        qup->config_run = is_first ? 0 : QUP_I2C_MX_CONFIG_DURING_RUN;

        qup_i2c_clear_blk_v2(blk);
        qup_i2c_conf_count_v2(qup);

        /* If it is first sub transfer, then configure i2c bus clocks */
        if (is_first) {
                ret = qup_i2c_change_state(qup, QUP_RUN_STATE);
                if (ret)
                        return ret;

                writel(qup->clk_ctl, qup->base + QUP_I2C_CLK_CTL);

                ret = qup_i2c_change_state(qup, QUP_PAUSE_STATE);
                if (ret)
                        return ret;
        }

        reinit_completion(&qup->xfer);
        enable_irq(qup->irq);
        /*
         * In FIFO mode, tx FIFO can be written directly while in block mode the
         * it will be written after getting OUT_BLOCK_WRITE_REQ interrupt
         */
        if (!blk->is_tx_blk_mode) {
                blk->tx_fifo_free = qup->out_fifo_sz;

                if (is_rx)
                        qup_i2c_write_rx_tags_v2(qup);
                else
                        qup_i2c_write_tx_fifo_v2(qup);
        }

        ret = qup_i2c_change_state(qup, QUP_RUN_STATE);
        if (ret)
                goto err;

        ret = qup_i2c_wait_for_complete(qup, msg);
        if (ret)
                goto err;

        /* Move to pause state for all the transfers, except last one */
        if (change_pause_state) {
                ret = qup_i2c_change_state(qup, QUP_PAUSE_STATE);
                if (ret)
                        goto err;
        }

err:
        disable_irq(qup->irq);
        return ret;
}

/*
 * Transfer one read/write message in i2c transfer. It splits the message into
 * multiple of blk_xfer_limit data length blocks and schedule each
 * QUP block individually.
 */
static int qup_i2c_xfer_v2_msg(struct qup_i2c_dev *qup, int msg_id, bool is_rx)
{
        int ret = 0;
        unsigned int data_len, i;
        struct i2c_msg *msg = qup->msg;
        struct qup_i2c_block *blk = &qup->blk;
        u8 *msg_buf = msg->buf;

        qup->blk_xfer_limit = is_rx ? RECV_MAX_DATA_LEN : QUP_READ_LIMIT;
        qup_i2c_set_blk_data(qup, msg);

        for (i = 0; i < blk->count; i++) {
                data_len =  qup_i2c_get_data_len(qup);
                blk->pos = i;
                blk->cur_tx_tags = blk->tags;
                blk->cur_blk_len = data_len;
                blk->tx_tag_len =
                        qup_i2c_set_tags(blk->cur_tx_tags, qup, qup->msg);

                blk->cur_data = msg_buf;

                if (is_rx) {
                        blk->total_tx_len = blk->tx_tag_len;
                        blk->rx_tag_len = 2;
                        blk->total_rx_len = blk->rx_tag_len + data_len;
                } else {
                        blk->total_tx_len = blk->tx_tag_len + data_len;
                        blk->total_rx_len = 0;
                }

                ret = qup_i2c_conf_xfer_v2(qup, is_rx, !msg_id && !i,
                                           !qup->is_last || i < blk->count - 1);
                if (ret)
                        return ret;

                /* Handle SMBus block read length */
                if (qup_i2c_check_msg_len(msg) && msg->len == 1 &&
                    !qup->is_smbus_read) {
                        if (msg->buf[0] > I2C_SMBUS_BLOCK_MAX)
                                return -EPROTO;

                        msg->len = msg->buf[0];
                        qup->is_smbus_read = true;
                        ret = qup_i2c_xfer_v2_msg(qup, msg_id, true);
                        qup->is_smbus_read = false;
                        if (ret)
                                return ret;

                        msg->len += 1;
                }

                msg_buf += data_len;
                blk->data_len -= qup->blk_xfer_limit;
        }

        return ret;
}

/*
 * QUP v2 supports 3 modes
 * Programmed IO using FIFO mode : Less than FIFO size
 * Programmed IO using Block mode : Greater than FIFO size
 * DMA using BAM : Appropriate for any transaction size but the address should
 *                 be DMA applicable
 *
 * This function determines the mode which will be used for this transfer. An
 * i2c transfer contains multiple message. Following are the rules to determine
 * the mode used.
 * 1. Determine complete length, maximum tx and rx length for complete transfer.
 * 2. If complete transfer length is greater than fifo size then use the DMA
 *    mode.
 * 3. In FIFO or block mode, tx and rx can operate in different mode so check
 *    for maximum tx and rx length to determine mode.
 */
static int
qup_i2c_determine_mode_v2(struct qup_i2c_dev *qup,
                          struct i2c_msg msgs[], int num)
{
        int idx;
        bool no_dma = false;
        unsigned int max_tx_len = 0, max_rx_len = 0, total_len = 0;

        /* All i2c_msgs should be transferred using either dma or cpu */
        for (idx = 0; idx < num; idx++) {
                if (msgs[idx].flags & I2C_M_RD)
                        max_rx_len = max_t(unsigned int, max_rx_len,
                                           msgs[idx].len);
                else
                        max_tx_len = max_t(unsigned int, max_tx_len,
                                           msgs[idx].len);

                if (is_vmalloc_addr(msgs[idx].buf))
                        no_dma = true;

                total_len += msgs[idx].len;
        }

        if (!no_dma && qup->is_dma &&
            (total_len > qup->out_fifo_sz || total_len > qup->in_fifo_sz)) {
                qup->use_dma = true;
        } else {
                qup->blk.is_tx_blk_mode = max_tx_len > qup->out_fifo_sz -
                        QUP_MAX_TAGS_LEN ? true : false;
                qup->blk.is_rx_blk_mode = max_rx_len > qup->in_fifo_sz -
                        READ_RX_TAGS_LEN ? true : false;
        }

        return 0;
}

static int qup_i2c_xfer_v2(struct i2c_adapter *adap,
                           struct i2c_msg msgs[],
                           int num)
{
        struct qup_i2c_dev *qup = i2c_get_adapdata(adap);
        int ret, idx = 0;

        qup->bus_err = 0;
        qup->qup_err = 0;

        ret = pm_runtime_get_sync(qup->dev);
        if (ret < 0)
                goto out;

        ret = qup_i2c_determine_mode_v2(qup, msgs, num);
        if (ret)
                goto out;

        writel(1, qup->base + QUP_SW_RESET);
        ret = qup_i2c_poll_state(qup, QUP_RESET_STATE);
        if (ret)
                goto out;

        /* Configure QUP as I2C mini core */
        writel(I2C_MINI_CORE | I2C_N_VAL_V2, qup->base + QUP_CONFIG);
        writel(QUP_V2_TAGS_EN, qup->base + QUP_I2C_MASTER_GEN);

        if (qup_i2c_poll_state_i2c_master(qup)) {
                ret = -EIO;
                goto out;
        }

        if (qup->use_dma) {
                reinit_completion(&qup->xfer);
                ret = qup_i2c_bam_xfer(adap, &msgs[0], num);
                qup->use_dma = false;
        } else {
                qup_i2c_conf_mode_v2(qup);

                for (idx = 0; idx < num; idx++) {
                        qup->msg = &msgs[idx];
                        qup->is_last = idx == (num - 1);

                        ret = qup_i2c_xfer_v2_msg(qup, idx,
                                        !!(msgs[idx].flags & I2C_M_RD));
                        if (ret)
                                break;
                }
                qup->msg = NULL;
        }

        if (!ret)
                ret = qup_i2c_bus_active(qup, ONE_BYTE);

        if (!ret)
                qup_i2c_change_state(qup, QUP_RESET_STATE);

        if (ret == 0)
                ret = num;
out:
        pm_runtime_mark_last_busy(qup->dev);
        pm_runtime_put_autosuspend(qup->dev);

        return ret;
}

static u32 qup_i2c_func(struct i2c_adapter *adap)
{
        return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
}

static const struct i2c_algorithm qup_i2c_algo = {
        .master_xfer    = qup_i2c_xfer,
        .functionality  = qup_i2c_func,
};

static const struct i2c_algorithm qup_i2c_algo_v2 = {
        .master_xfer    = qup_i2c_xfer_v2,
        .functionality  = qup_i2c_func,
};

/*
 * The QUP block will issue a NACK and STOP on the bus when reaching
 * the end of the read, the length of the read is specified as one byte
 * which limits the possible read to 256 (QUP_READ_LIMIT) bytes.
 */
static const struct i2c_adapter_quirks qup_i2c_quirks = {
        .flags = I2C_AQ_NO_ZERO_LEN,
        .max_read_len = QUP_READ_LIMIT,
};

static const struct i2c_adapter_quirks qup_i2c_quirks_v2 = {
        .flags = I2C_AQ_NO_ZERO_LEN,
};

static void qup_i2c_enable_clocks(struct qup_i2c_dev *qup)
{
        clk_prepare_enable(qup->clk);
        clk_prepare_enable(qup->pclk);
}

static void qup_i2c_disable_clocks(struct qup_i2c_dev *qup)
{
        u32 config;

        qup_i2c_change_state(qup, QUP_RESET_STATE);
        clk_disable_unprepare(qup->clk);
        config = readl(qup->base + QUP_CONFIG);
        config |= QUP_CLOCK_AUTO_GATE;
        writel(config, qup->base + QUP_CONFIG);
        clk_disable_unprepare(qup->pclk);
}

static const struct acpi_device_id qup_i2c_acpi_match[] = {
        { "QCOM8010"},
        { },
};
MODULE_DEVICE_TABLE(acpi, qup_i2c_acpi_match);

static int qup_i2c_probe(struct platform_device *pdev)
{
        static const int blk_sizes[] = {4, 16, 32};
        struct qup_i2c_dev *qup;
        unsigned long one_bit_t;
        struct resource *res;
        u32 io_mode, hw_ver, size;
        int ret, fs_div, hs_div;
        u32 src_clk_freq = DEFAULT_SRC_CLK;
        u32 clk_freq = DEFAULT_CLK_FREQ;
        int blocks;
        bool is_qup_v1;

        qup = devm_kzalloc(&pdev->dev, sizeof(*qup), GFP_KERNEL);
        if (!qup)
                return -ENOMEM;

        qup->dev = &pdev->dev;
        init_completion(&qup->xfer);
        platform_set_drvdata(pdev, qup);

        if (scl_freq) {
                dev_notice(qup->dev, "Using override frequency of %u\n", scl_freq);
                clk_freq = scl_freq;
        } else {
                ret = device_property_read_u32(qup->dev, "clock-frequency", &clk_freq);
                if (ret) {
                        dev_notice(qup->dev, "using default clock-frequency %d",
                                DEFAULT_CLK_FREQ);
                }
        }

        if (of_device_is_compatible(pdev->dev.of_node, "qcom,i2c-qup-v1.1.1")) {
                qup->adap.algo = &qup_i2c_algo;
                qup->adap.quirks = &qup_i2c_quirks;
                is_qup_v1 = true;
        } else {
                qup->adap.algo = &qup_i2c_algo_v2;
                qup->adap.quirks = &qup_i2c_quirks_v2;
                is_qup_v1 = false;
                if (acpi_match_device(qup_i2c_acpi_match, qup->dev))
                        goto nodma;
                else
                        ret = qup_i2c_req_dma(qup);

                if (ret == -EPROBE_DEFER)
                        goto fail_dma;
                else if (ret != 0)
                        goto nodma;

                qup->max_xfer_sg_len = (MX_BLOCKS << 1);
                blocks = (MX_DMA_BLOCKS << 1) + 1;
                qup->btx.sg = devm_kcalloc(&pdev->dev,
                                           blocks, sizeof(*qup->btx.sg),
                                           GFP_KERNEL);
                if (!qup->btx.sg) {
                        ret = -ENOMEM;
                        goto fail_dma;
                }
                sg_init_table(qup->btx.sg, blocks);

                qup->brx.sg = devm_kcalloc(&pdev->dev,
                                           blocks, sizeof(*qup->brx.sg),
                                           GFP_KERNEL);
                if (!qup->brx.sg) {
                        ret = -ENOMEM;
                        goto fail_dma;
                }
                sg_init_table(qup->brx.sg, blocks);

                /* 2 tag bytes for each block + 5 for start, stop tags */
                size = blocks * 2 + 5;

                qup->start_tag.start = devm_kzalloc(&pdev->dev,
                                                    size, GFP_KERNEL);
                if (!qup->start_tag.start) {
                        ret = -ENOMEM;
                        goto fail_dma;
                }

                qup->brx.tag.start = devm_kzalloc(&pdev->dev, 2, GFP_KERNEL);
                if (!qup->brx.tag.start) {
                        ret = -ENOMEM;
                        goto fail_dma;
                }

                qup->btx.tag.start = devm_kzalloc(&pdev->dev, 2, GFP_KERNEL);
                if (!qup->btx.tag.start) {
                        ret = -ENOMEM;
                        goto fail_dma;
                }
                qup->is_dma = true;
        }

nodma:
        /* We support frequencies up to FAST Mode Plus (1MHz) */
        if (!clk_freq || clk_freq > I2C_FAST_MODE_PLUS_FREQ) {
                dev_err(qup->dev, "clock frequency not supported %d\n",
                        clk_freq);
                return -EINVAL;
        }

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        qup->base = devm_ioremap_resource(qup->dev, res);
        if (IS_ERR(qup->base))
                return PTR_ERR(qup->base);

        qup->irq = platform_get_irq(pdev, 0);
        if (qup->irq < 0) {
                dev_err(qup->dev, "No IRQ defined\n");
                return qup->irq;
        }

        if (has_acpi_companion(qup->dev)) {
                ret = device_property_read_u32(qup->dev,
                                "src-clock-hz", &src_clk_freq);
                if (ret) {
                        dev_notice(qup->dev, "using default src-clock-hz %d",
                                DEFAULT_SRC_CLK);
                }
                ACPI_COMPANION_SET(&qup->adap.dev, ACPI_COMPANION(qup->dev));
        } else {
                qup->clk = devm_clk_get(qup->dev, "core");
                if (IS_ERR(qup->clk)) {
                        dev_err(qup->dev, "Could not get core clock\n");
                        return PTR_ERR(qup->clk);
                }

                qup->pclk = devm_clk_get(qup->dev, "iface");
                if (IS_ERR(qup->pclk)) {
                        dev_err(qup->dev, "Could not get iface clock\n");
                        return PTR_ERR(qup->pclk);
                }
                qup_i2c_enable_clocks(qup);
                src_clk_freq = clk_get_rate(qup->clk);
        }

        /*
         * Bootloaders might leave a pending interrupt on certain QUP's,
         * so we reset the core before registering for interrupts.
         */
        writel(1, qup->base + QUP_SW_RESET);
        ret = qup_i2c_poll_state_valid(qup);
        if (ret)
                goto fail;

        ret = devm_request_irq(qup->dev, qup->irq, qup_i2c_interrupt,
                               IRQF_TRIGGER_HIGH, "i2c_qup", qup);
        if (ret) {
                dev_err(qup->dev, "Request %d IRQ failed\n", qup->irq);
                goto fail;
        }
        disable_irq(qup->irq);

        hw_ver = readl(qup->base + QUP_HW_VERSION);
        dev_dbg(qup->dev, "Revision %x\n", hw_ver);

        io_mode = readl(qup->base + QUP_IO_MODE);

        /*
         * The block/fifo size w.r.t. 'actual data' is 1/2 due to 'tag'
         * associated with each byte written/received
         */
        size = QUP_OUTPUT_BLOCK_SIZE(io_mode);
        if (size >= ARRAY_SIZE(blk_sizes)) {
                ret = -EIO;
                goto fail;
        }
        qup->out_blk_sz = blk_sizes[size];

        size = QUP_INPUT_BLOCK_SIZE(io_mode);
        if (size >= ARRAY_SIZE(blk_sizes)) {
                ret = -EIO;
                goto fail;
        }
        qup->in_blk_sz = blk_sizes[size];

        if (is_qup_v1) {
                /*
                 * in QUP v1, QUP_CONFIG uses N as 15 i.e 16 bits constitutes a
                 * single transfer but the block size is in bytes so divide the
                 * in_blk_sz and out_blk_sz by 2
                 */
                qup->in_blk_sz /= 2;
                qup->out_blk_sz /= 2;
                qup->write_tx_fifo = qup_i2c_write_tx_fifo_v1;
                qup->read_rx_fifo = qup_i2c_read_rx_fifo_v1;
                qup->write_rx_tags = qup_i2c_write_rx_tags_v1;
        } else {
                qup->write_tx_fifo = qup_i2c_write_tx_fifo_v2;
                qup->read_rx_fifo = qup_i2c_read_rx_fifo_v2;
                qup->write_rx_tags = qup_i2c_write_rx_tags_v2;
        }

        size = QUP_OUTPUT_FIFO_SIZE(io_mode);
        qup->out_fifo_sz = qup->out_blk_sz * (2 << size);

        size = QUP_INPUT_FIFO_SIZE(io_mode);
        qup->in_fifo_sz = qup->in_blk_sz * (2 << size);

        hs_div = 3;
        if (clk_freq <= I2C_STANDARD_FREQ) {
                fs_div = ((src_clk_freq / clk_freq) / 2) - 3;
                qup->clk_ctl = (hs_div << 8) | (fs_div & 0xff);
        } else {
                /* 33%/66% duty cycle */
                fs_div = ((src_clk_freq / clk_freq) - 6) * 2 / 3;
                qup->clk_ctl = ((fs_div / 2) << 16) | (hs_div << 8) | (fs_div & 0xff);
        }

        /*
         * Time it takes for a byte to be clocked out on the bus.
         * Each byte takes 9 clock cycles (8 bits + 1 ack).
         */
        one_bit_t = (USEC_PER_SEC / clk_freq) + 1;
        qup->one_byte_t = one_bit_t * 9;
        qup->xfer_timeout = TOUT_MIN * HZ +
                usecs_to_jiffies(MX_DMA_TX_RX_LEN * qup->one_byte_t);

        dev_dbg(qup->dev, "IN:block:%d, fifo:%d, OUT:block:%d, fifo:%d\n",
                qup->in_blk_sz, qup->in_fifo_sz,
                qup->out_blk_sz, qup->out_fifo_sz);

        i2c_set_adapdata(&qup->adap, qup);
        qup->adap.dev.parent = qup->dev;
        qup->adap.dev.of_node = pdev->dev.of_node;
        qup->is_last = true;

        strlcpy(qup->adap.name, "QUP I2C adapter", sizeof(qup->adap.name));

        pm_runtime_set_autosuspend_delay(qup->dev, MSEC_PER_SEC);
        pm_runtime_use_autosuspend(qup->dev);
        pm_runtime_set_active(qup->dev);
        pm_runtime_enable(qup->dev);

        ret = i2c_add_adapter(&qup->adap);
        if (ret)
                goto fail_runtime;

        return 0;

fail_runtime:
        pm_runtime_disable(qup->dev);
        pm_runtime_set_suspended(qup->dev);
fail:
        qup_i2c_disable_clocks(qup);
fail_dma:
        if (qup->btx.dma)
                dma_release_channel(qup->btx.dma);
        if (qup->brx.dma)
                dma_release_channel(qup->brx.dma);
        return ret;
}

static int qup_i2c_remove(struct platform_device *pdev)
{
        struct qup_i2c_dev *qup = platform_get_drvdata(pdev);

        if (qup->is_dma) {
                dma_release_channel(qup->btx.dma);
                dma_release_channel(qup->brx.dma);
        }

        disable_irq(qup->irq);
        qup_i2c_disable_clocks(qup);
        i2c_del_adapter(&qup->adap);
        pm_runtime_disable(qup->dev);
        pm_runtime_set_suspended(qup->dev);
        return 0;
}

#ifdef CONFIG_PM
static int qup_i2c_pm_suspend_runtime(struct device *device)
{
        struct qup_i2c_dev *qup = dev_get_drvdata(device);

        dev_dbg(device, "pm_runtime: suspending...\n");
        qup_i2c_disable_clocks(qup);
        return 0;
}

static int qup_i2c_pm_resume_runtime(struct device *device)
{
        struct qup_i2c_dev *qup = dev_get_drvdata(device);

        dev_dbg(device, "pm_runtime: resuming...\n");
        qup_i2c_enable_clocks(qup);
        return 0;
}
#endif

#ifdef CONFIG_PM_SLEEP
static int qup_i2c_suspend(struct device *device)
{
        if (!pm_runtime_suspended(device))
                return qup_i2c_pm_suspend_runtime(device);
        return 0;
}

static int qup_i2c_resume(struct device *device)
{
        qup_i2c_pm_resume_runtime(device);
        pm_runtime_mark_last_busy(device);
        pm_request_autosuspend(device);
        return 0;
}
#endif

static const struct dev_pm_ops qup_i2c_qup_pm_ops = {
        SET_SYSTEM_SLEEP_PM_OPS(
                qup_i2c_suspend,
                qup_i2c_resume)
        SET_RUNTIME_PM_OPS(
                qup_i2c_pm_suspend_runtime,
                qup_i2c_pm_resume_runtime,
                NULL)
};

static const struct of_device_id qup_i2c_dt_match[] = {
        { .compatible = "qcom,i2c-qup-v1.1.1" },
        { .compatible = "qcom,i2c-qup-v2.1.1" },
        { .compatible = "qcom,i2c-qup-v2.2.1" },
        {}
};
MODULE_DEVICE_TABLE(of, qup_i2c_dt_match);

static struct platform_driver qup_i2c_driver = {
        .probe  = qup_i2c_probe,
        .remove = qup_i2c_remove,
        .driver = {
                .name = "i2c_qup",
                .pm = &qup_i2c_qup_pm_ops,
                .of_match_table = qup_i2c_dt_match,
                .acpi_match_table = ACPI_PTR(qup_i2c_acpi_match),
        },
};

module_platform_driver(qup_i2c_driver);

MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:i2c_qup");