/*
 *      Copyright (C) 2002 Motorola GSG-China
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version 2
 *      of the License, or (at your option) any later version.
 *
 *      This program is distributed in the hope that it will be useful,
 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *      GNU General Public License for more details.
 *
 * Author:
 *      Darius Augulis, Teltonika Inc.
 *
 * Desc.:
 *      Implementation of I2C Adapter/Algorithm Driver
 *      for I2C Bus integrated in Freescale i.MX/MXC processors
 *
 *      Derived from Motorola GSG China I2C example driver
 *
 *      Copyright (C) 2005 Torsten Koschorrek <koschorrek at synertronixx.de
 *      Copyright (C) 2005 Matthias Blaschke <blaschke at synertronixx.de
 *      Copyright (C) 2007 RightHand Technologies, Inc.
 *      Copyright (C) 2008 Darius Augulis <darius.augulis at teltonika.lt>
 *
 *      Copyright 2013 Freescale Semiconductor, Inc.
 *
 */

/** Includes *******************************************************************
*******************************************************************************/

#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/dmapool.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_dma.h>
#include <linux/platform_data/i2c-imx.h>
#include <linux/platform_device.h>
#include <linux/sched.h>
#include <linux/slab.h>

/** Defines ********************************************************************
*******************************************************************************/

/* This will be the driver name the kernel reports */
#define DRIVER_NAME "imx-i2c"

/* Default value */
#define IMX_I2C_BIT_RATE        100000  /* 100kHz */

/*
 * Enable DMA if transfer byte size is bigger than this threshold.
 * As the hardware request, it must bigger than 4 bytes.\
 * I have set '16' here, maybe it's not the best but I think it's
 * the appropriate.
 */
#define DMA_THRESHOLD   16
#define DMA_TIMEOUT     1000

/* IMX I2C registers:
 * the I2C register offset is different between SoCs,
 * to provid support for all these chips, split the
 * register offset into a fixed base address and a
 * variable shift value, then the full register offset
 * will be calculated by
 * reg_off = ( reg_base_addr << reg_shift)
 */
#define IMX_I2C_IADR    0x00    /* i2c slave address */
#define IMX_I2C_IFDR    0x01    /* i2c frequency divider */
#define IMX_I2C_I2CR    0x02    /* i2c control */
#define IMX_I2C_I2SR    0x03    /* i2c status */
#define IMX_I2C_I2DR    0x04    /* i2c transfer data */

#define IMX_I2C_REGSHIFT        2
#define VF610_I2C_REGSHIFT      0

/* Bits of IMX I2C registers */
#define I2SR_RXAK       0x01
#define I2SR_IIF        0x02
#define I2SR_SRW        0x04
#define I2SR_IAL        0x10
#define I2SR_IBB        0x20
#define I2SR_IAAS       0x40
#define I2SR_ICF        0x80
#define I2CR_DMAEN      0x02
#define I2CR_RSTA       0x04
#define I2CR_TXAK       0x08
#define I2CR_MTX        0x10
#define I2CR_MSTA       0x20
#define I2CR_IIEN       0x40
#define I2CR_IEN        0x80

/* register bits different operating codes definition:
 * 1) I2SR: Interrupt flags clear operation differ between SoCs:
 * - write zero to clear(w0c) INT flag on i.MX,
 * - but write one to clear(w1c) INT flag on Vybrid.
 * 2) I2CR: I2C module enable operation also differ between SoCs:
 * - set I2CR_IEN bit enable the module on i.MX,
 * - but clear I2CR_IEN bit enable the module on Vybrid.
 */
#define I2SR_CLR_OPCODE_W0C     0x0
#define I2SR_CLR_OPCODE_W1C     (I2SR_IAL | I2SR_IIF)
#define I2CR_IEN_OPCODE_0       0x0
#define I2CR_IEN_OPCODE_1       I2CR_IEN

/** Variables ******************************************************************
*******************************************************************************/

/*
 * sorted list of clock divider, register value pairs
 * taken from table 26-5, p.26-9, Freescale i.MX
 * Integrated Portable System Processor Reference Manual
 * Document Number: MC9328MXLRM, Rev. 5.1, 06/2007
 *
 * Duplicated divider values removed from list
 */
struct imx_i2c_clk_pair {
        u16     div;
        u16     val;
};

static struct imx_i2c_clk_pair imx_i2c_clk_div[] = {
        { 22,   0x20 }, { 24,   0x21 }, { 26,   0x22 }, { 28,   0x23 },
        { 30,   0x00 }, { 32,   0x24 }, { 36,   0x25 }, { 40,   0x26 },
        { 42,   0x03 }, { 44,   0x27 }, { 48,   0x28 }, { 52,   0x05 },
        { 56,   0x29 }, { 60,   0x06 }, { 64,   0x2A }, { 72,   0x2B },
        { 80,   0x2C }, { 88,   0x09 }, { 96,   0x2D }, { 104,  0x0A },
        { 112,  0x2E }, { 128,  0x2F }, { 144,  0x0C }, { 160,  0x30 },
        { 192,  0x31 }, { 224,  0x32 }, { 240,  0x0F }, { 256,  0x33 },
        { 288,  0x10 }, { 320,  0x34 }, { 384,  0x35 }, { 448,  0x36 },
        { 480,  0x13 }, { 512,  0x37 }, { 576,  0x14 }, { 640,  0x38 },
        { 768,  0x39 }, { 896,  0x3A }, { 960,  0x17 }, { 1024, 0x3B },
        { 1152, 0x18 }, { 1280, 0x3C }, { 1536, 0x3D }, { 1792, 0x3E },
        { 1920, 0x1B }, { 2048, 0x3F }, { 2304, 0x1C }, { 2560, 0x1D },
        { 3072, 0x1E }, { 3840, 0x1F }
};

/* Vybrid VF610 clock divider, register value pairs */
static struct imx_i2c_clk_pair vf610_i2c_clk_div[] = {
        { 20,   0x00 }, { 22,   0x01 }, { 24,   0x02 }, { 26,   0x03 },
        { 28,   0x04 }, { 30,   0x05 }, { 32,   0x09 }, { 34,   0x06 },
        { 36,   0x0A }, { 40,   0x07 }, { 44,   0x0C }, { 48,   0x0D },
        { 52,   0x43 }, { 56,   0x0E }, { 60,   0x45 }, { 64,   0x12 },
        { 68,   0x0F }, { 72,   0x13 }, { 80,   0x14 }, { 88,   0x15 },
        { 96,   0x19 }, { 104,  0x16 }, { 112,  0x1A }, { 128,  0x17 },
        { 136,  0x4F }, { 144,  0x1C }, { 160,  0x1D }, { 176,  0x55 },
        { 192,  0x1E }, { 208,  0x56 }, { 224,  0x22 }, { 228,  0x24 },
        { 240,  0x1F }, { 256,  0x23 }, { 288,  0x5C }, { 320,  0x25 },
        { 384,  0x26 }, { 448,  0x2A }, { 480,  0x27 }, { 512,  0x2B },
        { 576,  0x2C }, { 640,  0x2D }, { 768,  0x31 }, { 896,  0x32 },
        { 960,  0x2F }, { 1024, 0x33 }, { 1152, 0x34 }, { 1280, 0x35 },
        { 1536, 0x36 }, { 1792, 0x3A }, { 1920, 0x37 }, { 2048, 0x3B },
        { 2304, 0x3C }, { 2560, 0x3D }, { 3072, 0x3E }, { 3584, 0x7A },
        { 3840, 0x3F }, { 4096, 0x7B }, { 5120, 0x7D }, { 6144, 0x7E },
};

enum imx_i2c_type {
        IMX1_I2C,
        IMX21_I2C,
        VF610_I2C,
};

struct imx_i2c_hwdata {
        enum imx_i2c_type       devtype;
        unsigned                regshift;
        struct imx_i2c_clk_pair *clk_div;
        unsigned                ndivs;
        unsigned                i2sr_clr_opcode;
        unsigned                i2cr_ien_opcode;
};

struct imx_i2c_dma {
        struct dma_chan         *chan_tx;
        struct dma_chan         *chan_rx;
        struct dma_chan         *chan_using;
        struct completion       cmd_complete;
        dma_addr_t              dma_buf;
        unsigned int            dma_len;
        enum dma_transfer_direction dma_transfer_dir;
        enum dma_data_direction dma_data_dir;
};

struct imx_i2c_struct {
        struct i2c_adapter      adapter;
        struct clk              *clk;
        void __iomem            *base;
        wait_queue_head_t       queue;
        unsigned long           i2csr;
        unsigned int            disable_delay;
        int                     stopped;
        unsigned int            ifdr; /* IMX_I2C_IFDR */
        unsigned int            cur_clk;
        unsigned int            bitrate;
        const struct imx_i2c_hwdata     *hwdata;

        struct imx_i2c_dma      *dma;
};

static const struct imx_i2c_hwdata imx1_i2c_hwdata  = {
        .devtype                = IMX1_I2C,
        .regshift               = IMX_I2C_REGSHIFT,
        .clk_div                = imx_i2c_clk_div,
        .ndivs                  = ARRAY_SIZE(imx_i2c_clk_div),
        .i2sr_clr_opcode        = I2SR_CLR_OPCODE_W0C,
        .i2cr_ien_opcode        = I2CR_IEN_OPCODE_1,

};

static const struct imx_i2c_hwdata imx21_i2c_hwdata  = {
        .devtype                = IMX21_I2C,
        .regshift               = IMX_I2C_REGSHIFT,
        .clk_div                = imx_i2c_clk_div,
        .ndivs                  = ARRAY_SIZE(imx_i2c_clk_div),
        .i2sr_clr_opcode        = I2SR_CLR_OPCODE_W0C,
        .i2cr_ien_opcode        = I2CR_IEN_OPCODE_1,

};

static struct imx_i2c_hwdata vf610_i2c_hwdata = {
        .devtype                = VF610_I2C,
        .regshift               = VF610_I2C_REGSHIFT,
        .clk_div                = vf610_i2c_clk_div,
        .ndivs                  = ARRAY_SIZE(vf610_i2c_clk_div),
        .i2sr_clr_opcode        = I2SR_CLR_OPCODE_W1C,
        .i2cr_ien_opcode        = I2CR_IEN_OPCODE_0,

};

static struct platform_device_id imx_i2c_devtype[] = {
        {
                .name = "imx1-i2c",
                .driver_data = (kernel_ulong_t)&imx1_i2c_hwdata,
        }, {
                .name = "imx21-i2c",
                .driver_data = (kernel_ulong_t)&imx21_i2c_hwdata,
        }, {
                /* sentinel */
        }
};
MODULE_DEVICE_TABLE(platform, imx_i2c_devtype);

static const struct of_device_id i2c_imx_dt_ids[] = {
        { .compatible = "fsl,imx1-i2c", .data = &imx1_i2c_hwdata, },
        { .compatible = "fsl,imx21-i2c", .data = &imx21_i2c_hwdata, },
        { .compatible = "fsl,vf610-i2c", .data = &vf610_i2c_hwdata, },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, i2c_imx_dt_ids);

static inline int is_imx1_i2c(struct imx_i2c_struct *i2c_imx)
{
        return i2c_imx->hwdata->devtype == IMX1_I2C;
}

static inline void imx_i2c_write_reg(unsigned int val,
                struct imx_i2c_struct *i2c_imx, unsigned int reg)
{
        writeb(val, i2c_imx->base + (reg << i2c_imx->hwdata->regshift));
}

static inline unsigned char imx_i2c_read_reg(struct imx_i2c_struct *i2c_imx,
                unsigned int reg)
{
        return readb(i2c_imx->base + (reg << i2c_imx->hwdata->regshift));
}

/* Functions for DMA support */
static void i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx,
                                                dma_addr_t phy_addr)
{
        struct imx_i2c_dma *dma;
        struct dma_slave_config dma_sconfig;
        struct device *dev = &i2c_imx->adapter.dev;
        int ret;

        dma = devm_kzalloc(dev, sizeof(*dma), GFP_KERNEL);
        if (!dma)
                return;

        dma->chan_tx = dma_request_slave_channel(dev, "tx");
        if (!dma->chan_tx) {
                dev_dbg(dev, "can't request DMA tx channel\n");
                goto fail_al;
        }

        dma_sconfig.dst_addr = phy_addr +
                                (IMX_I2C_I2DR << i2c_imx->hwdata->regshift);
        dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
        dma_sconfig.dst_maxburst = 1;
        dma_sconfig.direction = DMA_MEM_TO_DEV;
        ret = dmaengine_slave_config(dma->chan_tx, &dma_sconfig);
        if (ret < 0) {
                dev_dbg(dev, "can't configure tx channel\n");
                goto fail_tx;
        }

        dma->chan_rx = dma_request_slave_channel(dev, "rx");
        if (!dma->chan_rx) {
                dev_dbg(dev, "can't request DMA rx channel\n");
                goto fail_tx;
        }

        dma_sconfig.src_addr = phy_addr +
                                (IMX_I2C_I2DR << i2c_imx->hwdata->regshift);
        dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
        dma_sconfig.src_maxburst = 1;
        dma_sconfig.direction = DMA_DEV_TO_MEM;
        ret = dmaengine_slave_config(dma->chan_rx, &dma_sconfig);
        if (ret < 0) {
                dev_dbg(dev, "can't configure rx channel\n");
                goto fail_rx;
        }

        i2c_imx->dma = dma;
        init_completion(&dma->cmd_complete);
        dev_info(dev, "using %s (tx) and %s (rx) for DMA transfers\n",
                dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx));

        return;

fail_rx:
        dma_release_channel(dma->chan_rx);
fail_tx:
        dma_release_channel(dma->chan_tx);
fail_al:
        devm_kfree(dev, dma);
        dev_info(dev, "can't use DMA\n");
}

static void i2c_imx_dma_callback(void *arg)
{
        struct imx_i2c_struct *i2c_imx = (struct imx_i2c_struct *)arg;
        struct imx_i2c_dma *dma = i2c_imx->dma;

        dma_unmap_single(dma->chan_using->device->dev, dma->dma_buf,
                        dma->dma_len, dma->dma_data_dir);
        complete(&dma->cmd_complete);
}

static int i2c_imx_dma_xfer(struct imx_i2c_struct *i2c_imx,
                                        struct i2c_msg *msgs)
{
        struct imx_i2c_dma *dma = i2c_imx->dma;
        struct dma_async_tx_descriptor *txdesc;
        struct device *dev = &i2c_imx->adapter.dev;
        struct device *chan_dev = dma->chan_using->device->dev;

        dma->dma_buf = dma_map_single(chan_dev, msgs->buf,
                                        dma->dma_len, dma->dma_data_dir);
        if (dma_mapping_error(chan_dev, dma->dma_buf)) {
                dev_err(dev, "DMA mapping failed\n");
                goto err_map;
        }

        txdesc = dmaengine_prep_slave_single(dma->chan_using, dma->dma_buf,
                                        dma->dma_len, dma->dma_transfer_dir,
                                        DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
        if (!txdesc) {
                dev_err(dev, "Not able to get desc for DMA xfer\n");
                goto err_desc;
        }

        txdesc->callback = i2c_imx_dma_callback;
        txdesc->callback_param = i2c_imx;
        if (dma_submit_error(dmaengine_submit(txdesc))) {
                dev_err(dev, "DMA submit failed\n");
                goto err_submit;
        }

        dma_async_issue_pending(dma->chan_using);
        return 0;

err_submit:
err_desc:
        dma_unmap_single(chan_dev, dma->dma_buf,
                        dma->dma_len, dma->dma_data_dir);
err_map:
        return -EINVAL;
}

static void i2c_imx_dma_free(struct imx_i2c_struct *i2c_imx)
{
        struct imx_i2c_dma *dma = i2c_imx->dma;

        dma->dma_buf = 0;
        dma->dma_len = 0;

        dma_release_channel(dma->chan_tx);
        dma->chan_tx = NULL;

        dma_release_channel(dma->chan_rx);
        dma->chan_rx = NULL;

        dma->chan_using = NULL;
}

/** Functions for IMX I2C adapter driver ***************************************
*******************************************************************************/

static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy)
{
        unsigned long orig_jiffies = jiffies;
        unsigned int temp;

        dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);

        while (1) {
                temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);

                /* check for arbitration lost */
                if (temp & I2SR_IAL) {
                        temp &= ~I2SR_IAL;
                        imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR);
                        return -EAGAIN;
                }

                if (for_busy && (temp & I2SR_IBB))
                        break;
                if (!for_busy && !(temp & I2SR_IBB))
                        break;
                if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
                        dev_dbg(&i2c_imx->adapter.dev,
                                "<%s> I2C bus is busy\n", __func__);
                        return -ETIMEDOUT;
                }
                schedule();
        }

        return 0;
}

static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx)
{
        wait_event_timeout(i2c_imx->queue, i2c_imx->i2csr & I2SR_IIF, HZ / 10);

        if (unlikely(!(i2c_imx->i2csr & I2SR_IIF))) {
                dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout\n", __func__);
                return -ETIMEDOUT;
        }
        dev_dbg(&i2c_imx->adapter.dev, "<%s> TRX complete\n", __func__);
        i2c_imx->i2csr = 0;
        return 0;
}

static int i2c_imx_acked(struct imx_i2c_struct *i2c_imx)
{
        if (imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR) & I2SR_RXAK) {
                dev_dbg(&i2c_imx->adapter.dev, "<%s> No ACK\n", __func__);
                return -EIO;  /* No ACK */
        }

        dev_dbg(&i2c_imx->adapter.dev, "<%s> ACK received\n", __func__);
        return 0;
}

static void i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx)
{
        struct imx_i2c_clk_pair *i2c_clk_div = i2c_imx->hwdata->clk_div;
        unsigned int i2c_clk_rate;
        unsigned int div;
        int i;

        /* Divider value calculation */
        i2c_clk_rate = clk_get_rate(i2c_imx->clk);
        if (i2c_imx->cur_clk == i2c_clk_rate)
                return;

        i2c_imx->cur_clk = i2c_clk_rate;

        div = (i2c_clk_rate + i2c_imx->bitrate - 1) / i2c_imx->bitrate;
        if (div < i2c_clk_div[0].div)
                i = 0;
        else if (div > i2c_clk_div[i2c_imx->hwdata->ndivs - 1].div)
                i = i2c_imx->hwdata->ndivs - 1;
        else
                for (i = 0; i2c_clk_div[i].div < div; i++)
                        ;

        /* Store divider value */
        i2c_imx->ifdr = i2c_clk_div[i].val;

        /*
         * There dummy delay is calculated.
         * It should be about one I2C clock period long.
         * This delay is used in I2C bus disable function
         * to fix chip hardware bug.
         */
        i2c_imx->disable_delay = (500000U * i2c_clk_div[i].div
                + (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2);

#ifdef CONFIG_I2C_DEBUG_BUS
        dev_dbg(&i2c_imx->adapter.dev, "I2C_CLK=%d, REQ DIV=%d\n",
                i2c_clk_rate, div);
        dev_dbg(&i2c_imx->adapter.dev, "IFDR[IC]=0x%x, REAL DIV=%d\n",
                i2c_clk_div[i].val, i2c_clk_div[i].div);
#endif
}

static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)
{
        unsigned int temp = 0;
        int result;

        dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);

        i2c_imx_set_clk(i2c_imx);

        result = clk_prepare_enable(i2c_imx->clk);
        if (result)
                return result;
        imx_i2c_write_reg(i2c_imx->ifdr, i2c_imx, IMX_I2C_IFDR);
        /* Enable I2C controller */
        imx_i2c_write_reg(i2c_imx->hwdata->i2sr_clr_opcode, i2c_imx, IMX_I2C_I2SR);
        imx_i2c_write_reg(i2c_imx->hwdata->i2cr_ien_opcode, i2c_imx, IMX_I2C_I2CR);

        /* Wait controller to be stable */
        udelay(50);

        /* Start I2C transaction */
        temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
        temp |= I2CR_MSTA;
        imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
        result = i2c_imx_bus_busy(i2c_imx, 1);
        if (result)
                return result;
        i2c_imx->stopped = 0;

        temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK;
        temp &= ~I2CR_DMAEN;
        imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
        return result;
}

static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
{
        unsigned int temp = 0;

        if (!i2c_imx->stopped) {
                /* Stop I2C transaction */
                dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
                temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
                temp &= ~(I2CR_MSTA | I2CR_MTX);
                if (i2c_imx->dma)
                        temp &= ~I2CR_DMAEN;
                imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
        }
        if (is_imx1_i2c(i2c_imx)) {
                /*
                 * This delay caused by an i.MXL hardware bug.
                 * If no (or too short) delay, no "STOP" bit will be generated.
                 */
                udelay(i2c_imx->disable_delay);
        }

        if (!i2c_imx->stopped) {
                i2c_imx_bus_busy(i2c_imx, 0);
                i2c_imx->stopped = 1;
        }

        /* Disable I2C controller */
        temp = i2c_imx->hwdata->i2cr_ien_opcode ^ I2CR_IEN,
        imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
        clk_disable_unprepare(i2c_imx->clk);
}

static irqreturn_t i2c_imx_isr(int irq, void *dev_id)
{
        struct imx_i2c_struct *i2c_imx = dev_id;
        unsigned int temp;

        temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
        if (temp & I2SR_IIF) {
                /* save status register */
                i2c_imx->i2csr = temp;
                temp &= ~I2SR_IIF;
                temp |= (i2c_imx->hwdata->i2sr_clr_opcode & I2SR_IIF);
                imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR);
                wake_up(&i2c_imx->queue);
                return IRQ_HANDLED;
        }

        return IRQ_NONE;
}

static int i2c_imx_dma_write(struct imx_i2c_struct *i2c_imx,
                                        struct i2c_msg *msgs)
{
        int result;
        unsigned long time_left;
        unsigned int temp = 0;
        unsigned long orig_jiffies = jiffies;
        struct imx_i2c_dma *dma = i2c_imx->dma;
        struct device *dev = &i2c_imx->adapter.dev;

        dma->chan_using = dma->chan_tx;
        dma->dma_transfer_dir = DMA_MEM_TO_DEV;
        dma->dma_data_dir = DMA_TO_DEVICE;
        dma->dma_len = msgs->len - 1;
        result = i2c_imx_dma_xfer(i2c_imx, msgs);
        if (result)
                return result;

        temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
        temp |= I2CR_DMAEN;
        imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);

        /*
         * Write slave address.
         * The first byte must be transmitted by the CPU.
         */
        imx_i2c_write_reg(msgs->addr << 1, i2c_imx, IMX_I2C_I2DR);
        reinit_completion(&i2c_imx->dma->cmd_complete);
        time_left = wait_for_completion_timeout(
                                &i2c_imx->dma->cmd_complete,
                                msecs_to_jiffies(DMA_TIMEOUT));
        if (time_left == 0) {
                dmaengine_terminate_all(dma->chan_using);
                return -ETIMEDOUT;
        }

        /* Waiting for transfer complete. */
        while (1) {
                temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
                if (temp & I2SR_ICF)
                        break;
                if (time_after(jiffies, orig_jiffies +
                                msecs_to_jiffies(DMA_TIMEOUT))) {
                        dev_dbg(dev, "<%s> Timeout\n", __func__);
                        return -ETIMEDOUT;
                }
                schedule();
        }

        temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
        temp &= ~I2CR_DMAEN;
        imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);

        /* The last data byte must be transferred by the CPU. */
        imx_i2c_write_reg(msgs->buf[msgs->len-1],
                                i2c_imx, IMX_I2C_I2DR);
        result = i2c_imx_trx_complete(i2c_imx);
        if (result)
                return result;

        return i2c_imx_acked(i2c_imx);
}

static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx,
                        struct i2c_msg *msgs, bool is_lastmsg)
{
        int result;
        unsigned long time_left;
        unsigned int temp;
        unsigned long orig_jiffies = jiffies;
        struct imx_i2c_dma *dma = i2c_imx->dma;
        struct device *dev = &i2c_imx->adapter.dev;

        temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
        temp |= I2CR_DMAEN;
        imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);

        dma->chan_using = dma->chan_rx;
        dma->dma_transfer_dir = DMA_DEV_TO_MEM;
        dma->dma_data_dir = DMA_FROM_DEVICE;
        /* The last two data bytes must be transferred by the CPU. */
        dma->dma_len = msgs->len - 2;
        result = i2c_imx_dma_xfer(i2c_imx, msgs);
        if (result)
                return result;

        reinit_completion(&i2c_imx->dma->cmd_complete);
        time_left = wait_for_completion_timeout(
                                &i2c_imx->dma->cmd_complete,
                                msecs_to_jiffies(DMA_TIMEOUT));
        if (time_left == 0) {
                dmaengine_terminate_all(dma->chan_using);
                return -ETIMEDOUT;
        }

        /* waiting for transfer complete. */
        while (1) {
                temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
                if (temp & I2SR_ICF)
                        break;
                if (time_after(jiffies, orig_jiffies +
                                msecs_to_jiffies(DMA_TIMEOUT))) {
                        dev_dbg(dev, "<%s> Timeout\n", __func__);
                        return -ETIMEDOUT;
                }
                schedule();
        }

        temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
        temp &= ~I2CR_DMAEN;
        imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);

        /* read n-1 byte data */
        temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
        temp |= I2CR_TXAK;
        imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);

        msgs->buf[msgs->len-2] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
        /* read n byte data */
        result = i2c_imx_trx_complete(i2c_imx);
        if (result)
                return result;

        if (is_lastmsg) {
                /*
                 * It must generate STOP before read I2DR to prevent
                 * controller from generating another clock cycle
                 */
                dev_dbg(dev, "<%s> clear MSTA\n", __func__);
                temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
                temp &= ~(I2CR_MSTA | I2CR_MTX);
                imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
                i2c_imx_bus_busy(i2c_imx, 0);
                i2c_imx->stopped = 1;
        } else {
                /*
                 * For i2c master receiver repeat restart operation like:
                 * read -> repeat MSTA -> read/write
                 * The controller must set MTX before read the last byte in
                 * the first read operation, otherwise the first read cost
                 * one extra clock cycle.
                 */
                temp = readb(i2c_imx->base + IMX_I2C_I2CR);
                temp |= I2CR_MTX;
                writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
        }
        msgs->buf[msgs->len-1] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);

        return 0;
}

static int i2c_imx_write(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
{
        int i, result;

        dev_dbg(&i2c_imx->adapter.dev, "<%s> write slave address: addr=0x%x\n",
                __func__, msgs->addr << 1);

        /* write slave address */
        imx_i2c_write_reg(msgs->addr << 1, i2c_imx, IMX_I2C_I2DR);
        result = i2c_imx_trx_complete(i2c_imx);
        if (result)
                return result;
        result = i2c_imx_acked(i2c_imx);
        if (result)
                return result;
        dev_dbg(&i2c_imx->adapter.dev, "<%s> write data\n", __func__);

        /* write data */
        for (i = 0; i < msgs->len; i++) {
                dev_dbg(&i2c_imx->adapter.dev,
                        "<%s> write byte: B%d=0x%X\n",
                        __func__, i, msgs->buf[i]);
                imx_i2c_write_reg(msgs->buf[i], i2c_imx, IMX_I2C_I2DR);
                result = i2c_imx_trx_complete(i2c_imx);
                if (result)
                        return result;
                result = i2c_imx_acked(i2c_imx);
                if (result)
                        return result;
        }
        return 0;
}

static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bool is_lastmsg)
{
        int i, result;
        unsigned int temp;
        int block_data = msgs->flags & I2C_M_RECV_LEN;

        dev_dbg(&i2c_imx->adapter.dev,
                "<%s> write slave address: addr=0x%x\n",
                __func__, (msgs->addr << 1) | 0x01);

        /* write slave address */
        imx_i2c_write_reg((msgs->addr << 1) | 0x01, i2c_imx, IMX_I2C_I2DR);
        result = i2c_imx_trx_complete(i2c_imx);
        if (result)
                return result;
        result = i2c_imx_acked(i2c_imx);
        if (result)
                return result;

        dev_dbg(&i2c_imx->adapter.dev, "<%s> setup bus\n", __func__);

        /* setup bus to read data */
        temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
        temp &= ~I2CR_MTX;

        /*
         * Reset the I2CR_TXAK flag initially for SMBus block read since the
         * length is unknown
         */
        if ((msgs->len - 1) || block_data)
                temp &= ~I2CR_TXAK;
        imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
        imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); /* dummy read */

        dev_dbg(&i2c_imx->adapter.dev, "<%s> read data\n", __func__);

        if (i2c_imx->dma && msgs->len >= DMA_THRESHOLD && !block_data)
                return i2c_imx_dma_read(i2c_imx, msgs, is_lastmsg);

        /* read data */
        for (i = 0; i < msgs->len; i++) {
                u8 len = 0;

                result = i2c_imx_trx_complete(i2c_imx);
                if (result)
                        return result;
                /*
                 * First byte is the length of remaining packet
                 * in the SMBus block data read. Add it to
                 * msgs->len.
                 */
                if ((!i) && block_data) {
                        len = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
                        if ((len == 0) || (len > I2C_SMBUS_BLOCK_MAX))
                                return -EPROTO;
                        dev_dbg(&i2c_imx->adapter.dev,
                                "<%s> read length: 0x%X\n",
                                __func__, len);
                        msgs->len += len;
                }
                if (i == (msgs->len - 1)) {
                        if (is_lastmsg) {
                                /*
                                 * It must generate STOP before read I2DR to prevent
                                 * controller from generating another clock cycle
                                 */
                                dev_dbg(&i2c_imx->adapter.dev,
                                        "<%s> clear MSTA\n", __func__);
                                temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
                                temp &= ~(I2CR_MSTA | I2CR_MTX);
                                imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
                                i2c_imx_bus_busy(i2c_imx, 0);
                                i2c_imx->stopped = 1;
                        } else {
                                /*
                                 * For i2c master receiver repeat restart operation like:
                                 * read -> repeat MSTA -> read/write
                                 * The controller must set MTX before read the last byte in
                                 * the first read operation, otherwise the first read cost
                                 * one extra clock cycle.
                                 */
                                temp = readb(i2c_imx->base + IMX_I2C_I2CR);
                                temp |= I2CR_MTX;
                                writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
                        }
                } else if (i == (msgs->len - 2)) {
                        dev_dbg(&i2c_imx->adapter.dev,
                                "<%s> set TXAK\n", __func__);
                        temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
                        temp |= I2CR_TXAK;
                        imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
                }
                if ((!i) && block_data)
                        msgs->buf[0] = len;
                else
                        msgs->buf[i] =  imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
                dev_dbg(&i2c_imx->adapter.dev,
                        "<%s> read byte: B%d=0x%X\n",
                        __func__, i, msgs->buf[i]);
        }
        return 0;
}

static int i2c_imx_xfer(struct i2c_adapter *adapter,
                                                struct i2c_msg *msgs, int num)
{
        unsigned int i, temp;
        int result;
        bool is_lastmsg = false;
        struct imx_i2c_struct *i2c_imx = i2c_get_adapdata(adapter);

        dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);

        /* Start I2C transfer */
        result = i2c_imx_start(i2c_imx);
        if (result)
                goto fail0;

        /* read/write data */
        for (i = 0; i < num; i++) {
                if (i == num - 1)
                        is_lastmsg = true;

                if (i) {
                        dev_dbg(&i2c_imx->adapter.dev,
                                "<%s> repeated start\n", __func__);
                        temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
                        temp |= I2CR_RSTA;
                        imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
                        result =  i2c_imx_bus_busy(i2c_imx, 1);
                        if (result)
                                goto fail0;
                }
                dev_dbg(&i2c_imx->adapter.dev,
                        "<%s> transfer message: %d\n", __func__, i);
                /* write/read data */
#ifdef CONFIG_I2C_DEBUG_BUS
                temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
                dev_dbg(&i2c_imx->adapter.dev,
                        "<%s> CONTROL: IEN=%d, IIEN=%d, MSTA=%d, MTX=%d, TXAK=%d, RSTA=%d\n",
                        __func__,
                        (temp & I2CR_IEN ? 1 : 0), (temp & I2CR_IIEN ? 1 : 0),
                        (temp & I2CR_MSTA ? 1 : 0), (temp & I2CR_MTX ? 1 : 0),
                        (temp & I2CR_TXAK ? 1 : 0), (temp & I2CR_RSTA ? 1 : 0));
                temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
                dev_dbg(&i2c_imx->adapter.dev,
                        "<%s> STATUS: ICF=%d, IAAS=%d, IBB=%d, IAL=%d, SRW=%d, IIF=%d, RXAK=%d\n",
                        __func__,
                        (temp & I2SR_ICF ? 1 : 0), (temp & I2SR_IAAS ? 1 : 0),
                        (temp & I2SR_IBB ? 1 : 0), (temp & I2SR_IAL ? 1 : 0),
                        (temp & I2SR_SRW ? 1 : 0), (temp & I2SR_IIF ? 1 : 0),
                        (temp & I2SR_RXAK ? 1 : 0));
#endif
                if (msgs[i].flags & I2C_M_RD)
                        result = i2c_imx_read(i2c_imx, &msgs[i], is_lastmsg);
                else {
                        if (i2c_imx->dma && msgs[i].len >= DMA_THRESHOLD)
                                result = i2c_imx_dma_write(i2c_imx, &msgs[i]);
                        else
                                result = i2c_imx_write(i2c_imx, &msgs[i]);
                }
                if (result)
                        goto fail0;
        }

fail0:
        /* Stop I2C transfer */
        i2c_imx_stop(i2c_imx);

        dev_dbg(&i2c_imx->adapter.dev, "<%s> exit with: %s: %d\n", __func__,
                (result < 0) ? "error" : "success msg",
                        (result < 0) ? result : num);
        return (result < 0) ? result : num;
}

static u32 i2c_imx_func(struct i2c_adapter *adapter)
{
        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL
                | I2C_FUNC_SMBUS_READ_BLOCK_DATA;
}

static struct i2c_algorithm i2c_imx_algo = {
        .master_xfer    = i2c_imx_xfer,
        .functionality  = i2c_imx_func,
};

static int i2c_imx_probe(struct platform_device *pdev)
{
        const struct of_device_id *of_id = of_match_device(i2c_imx_dt_ids,
                                                           &pdev->dev);
        struct imx_i2c_struct *i2c_imx;
        struct resource *res;
        struct imxi2c_platform_data *pdata = dev_get_platdata(&pdev->dev);
        void __iomem *base;
        int irq, ret;
        dma_addr_t phy_addr;

        dev_dbg(&pdev->dev, "<%s>\n", __func__);

        irq = platform_get_irq(pdev, 0);
        if (irq < 0) {
                dev_err(&pdev->dev, "can't get irq number\n");
                return irq;
        }

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

        phy_addr = (dma_addr_t)res->start;
        i2c_imx = devm_kzalloc(&pdev->dev, sizeof(*i2c_imx), GFP_KERNEL);
        if (!i2c_imx)
                return -ENOMEM;

        if (of_id)
                i2c_imx->hwdata = of_id->data;

        else
                i2c_imx->hwdata = (struct imx_i2c_hwdata *)
                                platform_get_device_id(pdev)->driver_data;

        /* Setup i2c_imx driver structure */
        strlcpy(i2c_imx->adapter.name, pdev->name, sizeof(i2c_imx->adapter.name));
        i2c_imx->adapter.owner          = THIS_MODULE;
        i2c_imx->adapter.algo           = &i2c_imx_algo;
        i2c_imx->adapter.dev.parent     = &pdev->dev;
        i2c_imx->adapter.nr             = pdev->id;
        i2c_imx->adapter.dev.of_node    = pdev->dev.of_node;
        i2c_imx->base                   = base;

        /* Get I2C clock */
        i2c_imx->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(i2c_imx->clk)) {
                dev_err(&pdev->dev, "can't get I2C clock\n");
                return PTR_ERR(i2c_imx->clk);
        }

        ret = clk_prepare_enable(i2c_imx->clk);
        if (ret) {
                dev_err(&pdev->dev, "can't enable I2C clock\n");
                return ret;
        }
        /* Request IRQ */
        ret = devm_request_irq(&pdev->dev, irq, i2c_imx_isr, 0,
                                pdev->name, i2c_imx);
        if (ret) {
                dev_err(&pdev->dev, "can't claim irq %d\n", irq);
                goto clk_disable;
        }

        /* Init queue */
        init_waitqueue_head(&i2c_imx->queue);

        /* Set up adapter data */
        i2c_set_adapdata(&i2c_imx->adapter, i2c_imx);

        /* Set up clock divider */
        i2c_imx->bitrate = IMX_I2C_BIT_RATE;
        ret = of_property_read_u32(pdev->dev.of_node,
                                   "clock-frequency", &i2c_imx->bitrate);
        if (ret < 0 && pdata && pdata->bitrate)
                i2c_imx->bitrate = pdata->bitrate;

        /* Set up chip registers to defaults */
        imx_i2c_write_reg(i2c_imx->hwdata->i2cr_ien_opcode ^ I2CR_IEN,
                        i2c_imx, IMX_I2C_I2CR);
        imx_i2c_write_reg(i2c_imx->hwdata->i2sr_clr_opcode, i2c_imx, IMX_I2C_I2SR);

        /* Add I2C adapter */
        ret = i2c_add_numbered_adapter(&i2c_imx->adapter);
        if (ret < 0) {
                dev_err(&pdev->dev, "registration failed\n");
                goto clk_disable;
        }

        /* Set up platform driver data */
        platform_set_drvdata(pdev, i2c_imx);
        clk_disable_unprepare(i2c_imx->clk);

        dev_dbg(&i2c_imx->adapter.dev, "claimed irq %d\n", irq);
        dev_dbg(&i2c_imx->adapter.dev, "device resources: %pR\n", res);
        dev_dbg(&i2c_imx->adapter.dev, "adapter name: \"%s\"\n",
                i2c_imx->adapter.name);
        dev_info(&i2c_imx->adapter.dev, "IMX I2C adapter registered\n");

        /* Init DMA config if supported */
        i2c_imx_dma_request(i2c_imx, phy_addr);

        return 0;   /* Return OK */

clk_disable:
        clk_disable_unprepare(i2c_imx->clk);
        return ret;
}

static int i2c_imx_remove(struct platform_device *pdev)
{
        struct imx_i2c_struct *i2c_imx = platform_get_drvdata(pdev);

        /* remove adapter */
        dev_dbg(&i2c_imx->adapter.dev, "adapter removed\n");
        i2c_del_adapter(&i2c_imx->adapter);

        if (i2c_imx->dma)
                i2c_imx_dma_free(i2c_imx);

        /* setup chip registers to defaults */
        imx_i2c_write_reg(0, i2c_imx, IMX_I2C_IADR);
        imx_i2c_write_reg(0, i2c_imx, IMX_I2C_IFDR);
        imx_i2c_write_reg(0, i2c_imx, IMX_I2C_I2CR);
        imx_i2c_write_reg(0, i2c_imx, IMX_I2C_I2SR);

        return 0;
}

static struct platform_driver i2c_imx_driver = {
        .probe = i2c_imx_probe,
        .remove = i2c_imx_remove,
        .driver = {
                .name   = DRIVER_NAME,
                .of_match_table = i2c_imx_dt_ids,
        },
        .id_table       = imx_i2c_devtype,
};

static int __init i2c_adap_imx_init(void)
{
        return platform_driver_register(&i2c_imx_driver);
}
subsys_initcall(i2c_adap_imx_init);

static void __exit i2c_adap_imx_exit(void)
{
        platform_driver_unregister(&i2c_imx_driver);
}
module_exit(i2c_adap_imx_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Darius Augulis");
MODULE_DESCRIPTION("I2C adapter driver for IMX I2C bus");
MODULE_ALIAS("platform:" DRIVER_NAME);