// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * TI OMAP I2C master mode driver
 *
 * Copyright (C) 2003 MontaVista Software, Inc.
 * Copyright (C) 2005 Nokia Corporation
 * Copyright (C) 2004 - 2007 Texas Instruments.
 *
 * Originally written by MontaVista Software, Inc.
 * Additional contributions by:
 *      Tony Lindgren <tony@atomide.com>
 *      Imre Deak <imre.deak@nokia.com>
 *      Juha Yrjölä <juha.yrjola@solidboot.com>
 *      Syed Khasim <x0khasim@ti.com>
 *      Nishant Menon <nm@ti.com>
 */

#include <linux/module.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/completion.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/slab.h>
#include <linux/platform_data/i2c-omap.h>
#include <linux/pm_runtime.h>
#include <linux/pinctrl/consumer.h>

/* I2C controller revisions */
#define OMAP_I2C_OMAP1_REV_2            0x20

/* I2C controller revisions present on specific hardware */
#define OMAP_I2C_REV_ON_2430            0x00000036
#define OMAP_I2C_REV_ON_3430_3530       0x0000003C
#define OMAP_I2C_REV_ON_3630            0x00000040
#define OMAP_I2C_REV_ON_4430_PLUS       0x50400002

/* timeout waiting for the controller to respond */
#define OMAP_I2C_TIMEOUT (msecs_to_jiffies(1000))

/* timeout for pm runtime autosuspend */
#define OMAP_I2C_PM_TIMEOUT             1000    /* ms */

/* timeout for making decision on bus free status */
#define OMAP_I2C_BUS_FREE_TIMEOUT (msecs_to_jiffies(10))

/* For OMAP3 I2C_IV has changed to I2C_WE (wakeup enable) */
enum {
        OMAP_I2C_REV_REG = 0,
        OMAP_I2C_IE_REG,
        OMAP_I2C_STAT_REG,
        OMAP_I2C_IV_REG,
        OMAP_I2C_WE_REG,
        OMAP_I2C_SYSS_REG,
        OMAP_I2C_BUF_REG,
        OMAP_I2C_CNT_REG,
        OMAP_I2C_DATA_REG,
        OMAP_I2C_SYSC_REG,
        OMAP_I2C_CON_REG,
        OMAP_I2C_OA_REG,
        OMAP_I2C_SA_REG,
        OMAP_I2C_PSC_REG,
        OMAP_I2C_SCLL_REG,
        OMAP_I2C_SCLH_REG,
        OMAP_I2C_SYSTEST_REG,
        OMAP_I2C_BUFSTAT_REG,
        /* only on OMAP4430 */
        OMAP_I2C_IP_V2_REVNB_LO,
        OMAP_I2C_IP_V2_REVNB_HI,
        OMAP_I2C_IP_V2_IRQSTATUS_RAW,
        OMAP_I2C_IP_V2_IRQENABLE_SET,
        OMAP_I2C_IP_V2_IRQENABLE_CLR,
};

/* I2C Interrupt Enable Register (OMAP_I2C_IE): */
#define OMAP_I2C_IE_XDR         (1 << 14)       /* TX Buffer drain int enable */
#define OMAP_I2C_IE_RDR         (1 << 13)       /* RX Buffer drain int enable */
#define OMAP_I2C_IE_XRDY        (1 << 4)        /* TX data ready int enable */
#define OMAP_I2C_IE_RRDY        (1 << 3)        /* RX data ready int enable */
#define OMAP_I2C_IE_ARDY        (1 << 2)        /* Access ready int enable */
#define OMAP_I2C_IE_NACK        (1 << 1)        /* No ack interrupt enable */
#define OMAP_I2C_IE_AL          (1 << 0)        /* Arbitration lost int ena */

/* I2C Status Register (OMAP_I2C_STAT): */
#define OMAP_I2C_STAT_XDR       (1 << 14)       /* TX Buffer draining */
#define OMAP_I2C_STAT_RDR       (1 << 13)       /* RX Buffer draining */
#define OMAP_I2C_STAT_BB        (1 << 12)       /* Bus busy */
#define OMAP_I2C_STAT_ROVR      (1 << 11)       /* Receive overrun */
#define OMAP_I2C_STAT_XUDF      (1 << 10)       /* Transmit underflow */
#define OMAP_I2C_STAT_AAS       (1 << 9)        /* Address as slave */
#define OMAP_I2C_STAT_BF        (1 << 8)        /* Bus Free */
#define OMAP_I2C_STAT_XRDY      (1 << 4)        /* Transmit data ready */
#define OMAP_I2C_STAT_RRDY      (1 << 3)        /* Receive data ready */
#define OMAP_I2C_STAT_ARDY      (1 << 2)        /* Register access ready */
#define OMAP_I2C_STAT_NACK      (1 << 1)        /* No ack interrupt enable */
#define OMAP_I2C_STAT_AL        (1 << 0)        /* Arbitration lost int ena */

/* I2C WE wakeup enable register */
#define OMAP_I2C_WE_XDR_WE      (1 << 14)       /* TX drain wakup */
#define OMAP_I2C_WE_RDR_WE      (1 << 13)       /* RX drain wakeup */
#define OMAP_I2C_WE_AAS_WE      (1 << 9)        /* Address as slave wakeup*/
#define OMAP_I2C_WE_BF_WE       (1 << 8)        /* Bus free wakeup */
#define OMAP_I2C_WE_STC_WE      (1 << 6)        /* Start condition wakeup */
#define OMAP_I2C_WE_GC_WE       (1 << 5)        /* General call wakeup */
#define OMAP_I2C_WE_DRDY_WE     (1 << 3)        /* TX/RX data ready wakeup */
#define OMAP_I2C_WE_ARDY_WE     (1 << 2)        /* Reg access ready wakeup */
#define OMAP_I2C_WE_NACK_WE     (1 << 1)        /* No acknowledgment wakeup */
#define OMAP_I2C_WE_AL_WE       (1 << 0)        /* Arbitration lost wakeup */

#define OMAP_I2C_WE_ALL         (OMAP_I2C_WE_XDR_WE | OMAP_I2C_WE_RDR_WE | \
                                OMAP_I2C_WE_AAS_WE | OMAP_I2C_WE_BF_WE | \
                                OMAP_I2C_WE_STC_WE | OMAP_I2C_WE_GC_WE | \
                                OMAP_I2C_WE_DRDY_WE | OMAP_I2C_WE_ARDY_WE | \
                                OMAP_I2C_WE_NACK_WE | OMAP_I2C_WE_AL_WE)

/* I2C Buffer Configuration Register (OMAP_I2C_BUF): */
#define OMAP_I2C_BUF_RDMA_EN    (1 << 15)       /* RX DMA channel enable */
#define OMAP_I2C_BUF_RXFIF_CLR  (1 << 14)       /* RX FIFO Clear */
#define OMAP_I2C_BUF_XDMA_EN    (1 << 7)        /* TX DMA channel enable */
#define OMAP_I2C_BUF_TXFIF_CLR  (1 << 6)        /* TX FIFO Clear */

/* I2C Configuration Register (OMAP_I2C_CON): */
#define OMAP_I2C_CON_EN         (1 << 15)       /* I2C module enable */
#define OMAP_I2C_CON_BE         (1 << 14)       /* Big endian mode */
#define OMAP_I2C_CON_OPMODE_HS  (1 << 12)       /* High Speed support */
#define OMAP_I2C_CON_STB        (1 << 11)       /* Start byte mode (master) */
#define OMAP_I2C_CON_MST        (1 << 10)       /* Master/slave mode */
#define OMAP_I2C_CON_TRX        (1 << 9)        /* TX/RX mode (master only) */
#define OMAP_I2C_CON_XA         (1 << 8)        /* Expand address */
#define OMAP_I2C_CON_RM         (1 << 2)        /* Repeat mode (master only) */
#define OMAP_I2C_CON_STP        (1 << 1)        /* Stop cond (master only) */
#define OMAP_I2C_CON_STT        (1 << 0)        /* Start condition (master) */

/* I2C SCL time value when Master */
#define OMAP_I2C_SCLL_HSSCLL    8
#define OMAP_I2C_SCLH_HSSCLH    8

/* I2C System Test Register (OMAP_I2C_SYSTEST): */
#define OMAP_I2C_SYSTEST_ST_EN          (1 << 15)       /* System test enable */
#define OMAP_I2C_SYSTEST_FREE           (1 << 14)       /* Free running mode */
#define OMAP_I2C_SYSTEST_TMODE_MASK     (3 << 12)       /* Test mode select */
#define OMAP_I2C_SYSTEST_TMODE_SHIFT    (12)            /* Test mode select */
/* Functional mode */
#define OMAP_I2C_SYSTEST_SCL_I_FUNC     (1 << 8)        /* SCL line input value */
#define OMAP_I2C_SYSTEST_SCL_O_FUNC     (1 << 7)        /* SCL line output value */
#define OMAP_I2C_SYSTEST_SDA_I_FUNC     (1 << 6)        /* SDA line input value */
#define OMAP_I2C_SYSTEST_SDA_O_FUNC     (1 << 5)        /* SDA line output value */
/* SDA/SCL IO mode */
#define OMAP_I2C_SYSTEST_SCL_I          (1 << 3)        /* SCL line sense in */
#define OMAP_I2C_SYSTEST_SCL_O          (1 << 2)        /* SCL line drive out */
#define OMAP_I2C_SYSTEST_SDA_I          (1 << 1)        /* SDA line sense in */
#define OMAP_I2C_SYSTEST_SDA_O          (1 << 0)        /* SDA line drive out */

/* OCP_SYSSTATUS bit definitions */
#define SYSS_RESETDONE_MASK             (1 << 0)

/* OCP_SYSCONFIG bit definitions */
#define SYSC_CLOCKACTIVITY_MASK         (0x3 << 8)
#define SYSC_SIDLEMODE_MASK             (0x3 << 3)
#define SYSC_ENAWAKEUP_MASK             (1 << 2)
#define SYSC_SOFTRESET_MASK             (1 << 1)
#define SYSC_AUTOIDLE_MASK              (1 << 0)

#define SYSC_IDLEMODE_SMART             0x2
#define SYSC_CLOCKACTIVITY_FCLK         0x2

/* Errata definitions */
#define I2C_OMAP_ERRATA_I207            (1 << 0)
#define I2C_OMAP_ERRATA_I462            (1 << 1)

#define OMAP_I2C_IP_V2_INTERRUPTS_MASK  0x6FFF

struct omap_i2c_dev {
        struct device           *dev;
        void __iomem            *base;          /* virtual */
        int                     irq;
        int                     reg_shift;      /* bit shift for I2C register addresses */
        struct completion       cmd_complete;
        struct resource         *ioarea;
        u32                     latency;        /* maximum mpu wkup latency */
        void                    (*set_mpu_wkup_lat)(struct device *dev,
                                                    long latency);
        u32                     speed;          /* Speed of bus in kHz */
        u32                     flags;
        u16                     scheme;
        u16                     cmd_err;
        u8                      *buf;
        u8                      *regs;
        size_t                  buf_len;
        struct i2c_adapter      adapter;
        u8                      threshold;
        u8                      fifo_size;      /* use as flag and value
                                                 * fifo_size==0 implies no fifo
                                                 * if set, should be trsh+1
                                                 */
        u32                     rev;
        unsigned                b_hw:1;         /* bad h/w fixes */
        unsigned                bb_valid:1;     /* true when BB-bit reflects
                                                 * the I2C bus state
                                                 */
        unsigned                receiver:1;     /* true when we're in receiver mode */
        u16                     iestate;        /* Saved interrupt register */
        u16                     pscstate;
        u16                     scllstate;
        u16                     sclhstate;
        u16                     syscstate;
        u16                     westate;
        u16                     errata;
};

static const u8 reg_map_ip_v1[] = {
        [OMAP_I2C_REV_REG] = 0x00,
        [OMAP_I2C_IE_REG] = 0x01,
        [OMAP_I2C_STAT_REG] = 0x02,
        [OMAP_I2C_IV_REG] = 0x03,
        [OMAP_I2C_WE_REG] = 0x03,
        [OMAP_I2C_SYSS_REG] = 0x04,
        [OMAP_I2C_BUF_REG] = 0x05,
        [OMAP_I2C_CNT_REG] = 0x06,
        [OMAP_I2C_DATA_REG] = 0x07,
        [OMAP_I2C_SYSC_REG] = 0x08,
        [OMAP_I2C_CON_REG] = 0x09,
        [OMAP_I2C_OA_REG] = 0x0a,
        [OMAP_I2C_SA_REG] = 0x0b,
        [OMAP_I2C_PSC_REG] = 0x0c,
        [OMAP_I2C_SCLL_REG] = 0x0d,
        [OMAP_I2C_SCLH_REG] = 0x0e,
        [OMAP_I2C_SYSTEST_REG] = 0x0f,
        [OMAP_I2C_BUFSTAT_REG] = 0x10,
};

static const u8 reg_map_ip_v2[] = {
        [OMAP_I2C_REV_REG] = 0x04,
        [OMAP_I2C_IE_REG] = 0x2c,
        [OMAP_I2C_STAT_REG] = 0x28,
        [OMAP_I2C_IV_REG] = 0x34,
        [OMAP_I2C_WE_REG] = 0x34,
        [OMAP_I2C_SYSS_REG] = 0x90,
        [OMAP_I2C_BUF_REG] = 0x94,
        [OMAP_I2C_CNT_REG] = 0x98,
        [OMAP_I2C_DATA_REG] = 0x9c,
        [OMAP_I2C_SYSC_REG] = 0x10,
        [OMAP_I2C_CON_REG] = 0xa4,
        [OMAP_I2C_OA_REG] = 0xa8,
        [OMAP_I2C_SA_REG] = 0xac,
        [OMAP_I2C_PSC_REG] = 0xb0,
        [OMAP_I2C_SCLL_REG] = 0xb4,
        [OMAP_I2C_SCLH_REG] = 0xb8,
        [OMAP_I2C_SYSTEST_REG] = 0xbC,
        [OMAP_I2C_BUFSTAT_REG] = 0xc0,
        [OMAP_I2C_IP_V2_REVNB_LO] = 0x00,
        [OMAP_I2C_IP_V2_REVNB_HI] = 0x04,
        [OMAP_I2C_IP_V2_IRQSTATUS_RAW] = 0x24,
        [OMAP_I2C_IP_V2_IRQENABLE_SET] = 0x2c,
        [OMAP_I2C_IP_V2_IRQENABLE_CLR] = 0x30,
};

static int omap_i2c_xfer_data(struct omap_i2c_dev *omap);

static inline void omap_i2c_write_reg(struct omap_i2c_dev *omap,
                                      int reg, u16 val)
{
        writew_relaxed(val, omap->base +
                        (omap->regs[reg] << omap->reg_shift));
}

static inline u16 omap_i2c_read_reg(struct omap_i2c_dev *omap, int reg)
{
        return readw_relaxed(omap->base +
                                (omap->regs[reg] << omap->reg_shift));
}

static void __omap_i2c_init(struct omap_i2c_dev *omap)
{

        omap_i2c_write_reg(omap, OMAP_I2C_CON_REG, 0);

        /* Setup clock prescaler to obtain approx 12MHz I2C module clock: */
        omap_i2c_write_reg(omap, OMAP_I2C_PSC_REG, omap->pscstate);

        /* SCL low and high time values */
        omap_i2c_write_reg(omap, OMAP_I2C_SCLL_REG, omap->scllstate);
        omap_i2c_write_reg(omap, OMAP_I2C_SCLH_REG, omap->sclhstate);
        if (omap->rev >= OMAP_I2C_REV_ON_3430_3530)
                omap_i2c_write_reg(omap, OMAP_I2C_WE_REG, omap->westate);

        /* Take the I2C module out of reset: */
        omap_i2c_write_reg(omap, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);

        /*
         * NOTE: right after setting CON_EN, STAT_BB could be 0 while the
         * bus is busy. It will be changed to 1 on the next IP FCLK clock.
         * udelay(1) will be enough to fix that.
         */

        /*
         * Don't write to this register if the IE state is 0 as it can
         * cause deadlock.
         */
        if (omap->iestate)
                omap_i2c_write_reg(omap, OMAP_I2C_IE_REG, omap->iestate);
}

static int omap_i2c_reset(struct omap_i2c_dev *omap)
{
        unsigned long timeout;
        u16 sysc;

        if (omap->rev >= OMAP_I2C_OMAP1_REV_2) {
                sysc = omap_i2c_read_reg(omap, OMAP_I2C_SYSC_REG);

                /* Disable I2C controller before soft reset */
                omap_i2c_write_reg(omap, OMAP_I2C_CON_REG,
                        omap_i2c_read_reg(omap, OMAP_I2C_CON_REG) &
                                ~(OMAP_I2C_CON_EN));

                omap_i2c_write_reg(omap, OMAP_I2C_SYSC_REG, SYSC_SOFTRESET_MASK);
                /* For some reason we need to set the EN bit before the
                 * reset done bit gets set. */
                timeout = jiffies + OMAP_I2C_TIMEOUT;
                omap_i2c_write_reg(omap, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);
                while (!(omap_i2c_read_reg(omap, OMAP_I2C_SYSS_REG) &
                         SYSS_RESETDONE_MASK)) {
                        if (time_after(jiffies, timeout)) {
                                dev_warn(omap->dev, "timeout waiting "
                                                "for controller reset\n");
                                return -ETIMEDOUT;
                        }
                        msleep(1);
                }

                /* SYSC register is cleared by the reset; rewrite it */
                omap_i2c_write_reg(omap, OMAP_I2C_SYSC_REG, sysc);

                if (omap->rev > OMAP_I2C_REV_ON_3430_3530) {
                        /* Schedule I2C-bus monitoring on the next transfer */
                        omap->bb_valid = 0;
                }
        }

        return 0;
}

static int omap_i2c_init(struct omap_i2c_dev *omap)
{
        u16 psc = 0, scll = 0, sclh = 0;
        u16 fsscll = 0, fssclh = 0, hsscll = 0, hssclh = 0;
        unsigned long fclk_rate = 12000000;
        unsigned long internal_clk = 0;
        struct clk *fclk;
        int error;

        if (omap->rev >= OMAP_I2C_REV_ON_3430_3530) {
                /*
                 * Enabling all wakup sources to stop I2C freezing on
                 * WFI instruction.
                 * REVISIT: Some wkup sources might not be needed.
                 */
                omap->westate = OMAP_I2C_WE_ALL;
        }

        if (omap->flags & OMAP_I2C_FLAG_ALWAYS_ARMXOR_CLK) {
                /*
                 * The I2C functional clock is the armxor_ck, so there's
                 * no need to get "armxor_ck" separately.  Now, if OMAP2420
                 * always returns 12MHz for the functional clock, we can
                 * do this bit unconditionally.
                 */
                fclk = clk_get(omap->dev, "fck");
                if (IS_ERR(fclk)) {
                        error = PTR_ERR(fclk);
                        dev_err(omap->dev, "could not get fck: %i\n", error);

                        return error;
                }

                fclk_rate = clk_get_rate(fclk);
                clk_put(fclk);

                /* TRM for 5912 says the I2C clock must be prescaled to be
                 * between 7 - 12 MHz. The XOR input clock is typically
                 * 12, 13 or 19.2 MHz. So we should have code that produces:
                 *
                 * XOR MHz      Divider         Prescaler
                 * 12           1               0
                 * 13           2               1
                 * 19.2         2               1
                 */
                if (fclk_rate > 12000000)
                        psc = fclk_rate / 12000000;
        }

        if (!(omap->flags & OMAP_I2C_FLAG_SIMPLE_CLOCK)) {

                /*
                 * HSI2C controller internal clk rate should be 19.2 Mhz for
                 * HS and for all modes on 2430. On 34xx we can use lower rate
                 * to get longer filter period for better noise suppression.
                 * The filter is iclk (fclk for HS) period.
                 */
                if (omap->speed > 400 ||
                               omap->flags & OMAP_I2C_FLAG_FORCE_19200_INT_CLK)
                        internal_clk = 19200;
                else if (omap->speed > 100)
                        internal_clk = 9600;
                else
                        internal_clk = 4000;
                fclk = clk_get(omap->dev, "fck");
                if (IS_ERR(fclk)) {
                        error = PTR_ERR(fclk);
                        dev_err(omap->dev, "could not get fck: %i\n", error);

                        return error;
                }
                fclk_rate = clk_get_rate(fclk) / 1000;
                clk_put(fclk);

                /* Compute prescaler divisor */
                psc = fclk_rate / internal_clk;
                psc = psc - 1;

                /* If configured for High Speed */
                if (omap->speed > 400) {
                        unsigned long scl;

                        /* For first phase of HS mode */
                        scl = internal_clk / 400;
                        fsscll = scl - (scl / 3) - 7;
                        fssclh = (scl / 3) - 5;

                        /* For second phase of HS mode */
                        scl = fclk_rate / omap->speed;
                        hsscll = scl - (scl / 3) - 7;
                        hssclh = (scl / 3) - 5;
                } else if (omap->speed > 100) {
                        unsigned long scl;

                        /* Fast mode */
                        scl = internal_clk / omap->speed;
                        fsscll = scl - (scl / 3) - 7;
                        fssclh = (scl / 3) - 5;
                } else {
                        /* Standard mode */
                        fsscll = internal_clk / (omap->speed * 2) - 7;
                        fssclh = internal_clk / (omap->speed * 2) - 5;
                }
                scll = (hsscll << OMAP_I2C_SCLL_HSSCLL) | fsscll;
                sclh = (hssclh << OMAP_I2C_SCLH_HSSCLH) | fssclh;
        } else {
                /* Program desired operating rate */
                fclk_rate /= (psc + 1) * 1000;
                if (psc > 2)
                        psc = 2;
                scll = fclk_rate / (omap->speed * 2) - 7 + psc;
                sclh = fclk_rate / (omap->speed * 2) - 7 + psc;
        }

        omap->iestate = (OMAP_I2C_IE_XRDY | OMAP_I2C_IE_RRDY |
                        OMAP_I2C_IE_ARDY | OMAP_I2C_IE_NACK |
                        OMAP_I2C_IE_AL)  | ((omap->fifo_size) ?
                                (OMAP_I2C_IE_RDR | OMAP_I2C_IE_XDR) : 0);

        omap->pscstate = psc;
        omap->scllstate = scll;
        omap->sclhstate = sclh;

        if (omap->rev <= OMAP_I2C_REV_ON_3430_3530) {
                /* Not implemented */
                omap->bb_valid = 1;
        }

        __omap_i2c_init(omap);

        return 0;
}

/*
 * Try bus recovery, but only if SDA is actually low.
 */
static int omap_i2c_recover_bus(struct omap_i2c_dev *omap)
{
        u16 systest;

        systest = omap_i2c_read_reg(omap, OMAP_I2C_SYSTEST_REG);
        if ((systest & OMAP_I2C_SYSTEST_SCL_I_FUNC) &&
            (systest & OMAP_I2C_SYSTEST_SDA_I_FUNC))
                return 0; /* bus seems to already be fine */
        if (!(systest & OMAP_I2C_SYSTEST_SCL_I_FUNC))
                return -EBUSY; /* recovery would not fix SCL */
        return i2c_recover_bus(&omap->adapter);
}

/*
 * Waiting on Bus Busy
 */
static int omap_i2c_wait_for_bb(struct omap_i2c_dev *omap)
{
        unsigned long timeout;

        timeout = jiffies + OMAP_I2C_TIMEOUT;
        while (omap_i2c_read_reg(omap, OMAP_I2C_STAT_REG) & OMAP_I2C_STAT_BB) {
                if (time_after(jiffies, timeout))
                        return omap_i2c_recover_bus(omap);
                msleep(1);
        }

        return 0;
}

/*
 * Wait while BB-bit doesn't reflect the I2C bus state
 *
 * In a multimaster environment, after IP software reset, BB-bit value doesn't
 * correspond to the current bus state. It may happen what BB-bit will be 0,
 * while the bus is busy due to another I2C master activity.
 * Here are BB-bit values after reset:
 *     SDA   SCL   BB   NOTES
 *       0     0    0   1, 2
 *       1     0    0   1, 2
 *       0     1    1
 *       1     1    0   3
 * Later, if IP detect SDA=0 and SCL=1 (ACK) or SDA 1->0 while SCL=1 (START)
 * combinations on the bus, it set BB-bit to 1.
 * If IP detect SDA 0->1 while SCL=1 (STOP) combination on the bus,
 * it set BB-bit to 0 and BF to 1.
 * BB and BF bits correctly tracks the bus state while IP is suspended
 * BB bit became valid on the next FCLK clock after CON_EN bit set
 *
 * NOTES:
 * 1. Any transfer started when BB=0 and bus is busy wouldn't be
 *    completed by IP and results in controller timeout.
 * 2. Any transfer started when BB=0 and SCL=0 results in IP
 *    starting to drive SDA low. In that case IP corrupt data
 *    on the bus.
 * 3. Any transfer started in the middle of another master's transfer
 *    results in unpredictable results and data corruption
 */
static int omap_i2c_wait_for_bb_valid(struct omap_i2c_dev *omap)
{
        unsigned long bus_free_timeout = 0;
        unsigned long timeout;
        int bus_free = 0;
        u16 stat, systest;

        if (omap->bb_valid)
                return 0;

        timeout = jiffies + OMAP_I2C_TIMEOUT;
        while (1) {
                stat = omap_i2c_read_reg(omap, OMAP_I2C_STAT_REG);
                /*
                 * We will see BB or BF event in a case IP had detected any
                 * activity on the I2C bus. Now IP correctly tracks the bus
                 * state. BB-bit value is valid.
                 */
                if (stat & (OMAP_I2C_STAT_BB | OMAP_I2C_STAT_BF))
                        break;

                /*
                 * Otherwise, we must look signals on the bus to make
                 * the right decision.
                 */
                systest = omap_i2c_read_reg(omap, OMAP_I2C_SYSTEST_REG);
                if ((systest & OMAP_I2C_SYSTEST_SCL_I_FUNC) &&
                    (systest & OMAP_I2C_SYSTEST_SDA_I_FUNC)) {
                        if (!bus_free) {
                                bus_free_timeout = jiffies +
                                        OMAP_I2C_BUS_FREE_TIMEOUT;
                                bus_free = 1;
                        }

                        /*
                         * SDA and SCL lines was high for 10 ms without bus
                         * activity detected. The bus is free. Consider
                         * BB-bit value is valid.
                         */
                        if (time_after(jiffies, bus_free_timeout))
                                break;
                } else {
                        bus_free = 0;
                }

                if (time_after(jiffies, timeout)) {
                        /*
                         * SDA or SCL were low for the entire timeout without
                         * any activity detected. Most likely, a slave is
                         * locking up the bus with no master driving the clock.
                         */
                        dev_warn(omap->dev, "timeout waiting for bus ready\n");
                        return omap_i2c_recover_bus(omap);
                }

                msleep(1);
        }

        omap->bb_valid = 1;
        return 0;
}

static void omap_i2c_resize_fifo(struct omap_i2c_dev *omap, u8 size, bool is_rx)
{
        u16             buf;

        if (omap->flags & OMAP_I2C_FLAG_NO_FIFO)
                return;

        /*
         * Set up notification threshold based on message size. We're doing
         * this to try and avoid draining feature as much as possible. Whenever
         * we have big messages to transfer (bigger than our total fifo size)
         * then we might use draining feature to transfer the remaining bytes.
         */

        omap->threshold = clamp(size, (u8) 1, omap->fifo_size);

        buf = omap_i2c_read_reg(omap, OMAP_I2C_BUF_REG);

        if (is_rx) {
                /* Clear RX Threshold */
                buf &= ~(0x3f << 8);
                buf |= ((omap->threshold - 1) << 8) | OMAP_I2C_BUF_RXFIF_CLR;
        } else {
                /* Clear TX Threshold */
                buf &= ~0x3f;
                buf |= (omap->threshold - 1) | OMAP_I2C_BUF_TXFIF_CLR;
        }

        omap_i2c_write_reg(omap, OMAP_I2C_BUF_REG, buf);

        if (omap->rev < OMAP_I2C_REV_ON_3630)
                omap->b_hw = 1; /* Enable hardware fixes */

        /* calculate wakeup latency constraint for MPU */
        if (omap->set_mpu_wkup_lat != NULL)
                omap->latency = (1000000 * omap->threshold) /
                        (1000 * omap->speed / 8);
}

static void omap_i2c_wait(struct omap_i2c_dev *omap)
{
        u16 stat;
        u16 mask = omap_i2c_read_reg(omap, OMAP_I2C_IE_REG);
        int count = 0;

        do {
                stat = omap_i2c_read_reg(omap, OMAP_I2C_STAT_REG);
                count++;
        } while (!(stat & mask) && count < 5);
}

/*
 * Low level master read/write transaction.
 */
static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
                             struct i2c_msg *msg, int stop, bool polling)
{
        struct omap_i2c_dev *omap = i2c_get_adapdata(adap);
        unsigned long timeout;
        u16 w;
        int ret;

        dev_dbg(omap->dev, "addr: 0x%04x, len: %d, flags: 0x%x, stop: %d\n",
                msg->addr, msg->len, msg->flags, stop);

        omap->receiver = !!(msg->flags & I2C_M_RD);
        omap_i2c_resize_fifo(omap, msg->len, omap->receiver);

        omap_i2c_write_reg(omap, OMAP_I2C_SA_REG, msg->addr);

        /* REVISIT: Could the STB bit of I2C_CON be used with probing? */
        omap->buf = msg->buf;
        omap->buf_len = msg->len;

        /* make sure writes to omap->buf_len are ordered */
        barrier();

        omap_i2c_write_reg(omap, OMAP_I2C_CNT_REG, omap->buf_len);

        /* Clear the FIFO Buffers */
        w = omap_i2c_read_reg(omap, OMAP_I2C_BUF_REG);
        w |= OMAP_I2C_BUF_RXFIF_CLR | OMAP_I2C_BUF_TXFIF_CLR;
        omap_i2c_write_reg(omap, OMAP_I2C_BUF_REG, w);

        if (!polling)
                reinit_completion(&omap->cmd_complete);
        omap->cmd_err = 0;

        w = OMAP_I2C_CON_EN | OMAP_I2C_CON_MST | OMAP_I2C_CON_STT;

        /* High speed configuration */
        if (omap->speed > 400)
                w |= OMAP_I2C_CON_OPMODE_HS;

        if (msg->flags & I2C_M_STOP)
                stop = 1;
        if (msg->flags & I2C_M_TEN)
                w |= OMAP_I2C_CON_XA;
        if (!(msg->flags & I2C_M_RD))
                w |= OMAP_I2C_CON_TRX;

        if (!omap->b_hw && stop)
                w |= OMAP_I2C_CON_STP;
        /*
         * NOTE: STAT_BB bit could became 1 here if another master occupy
         * the bus. IP successfully complete transfer when the bus will be
         * free again (BB reset to 0).
         */
        omap_i2c_write_reg(omap, OMAP_I2C_CON_REG, w);

        /*
         * Don't write stt and stp together on some hardware.
         */
        if (omap->b_hw && stop) {
                unsigned long delay = jiffies + OMAP_I2C_TIMEOUT;
                u16 con = omap_i2c_read_reg(omap, OMAP_I2C_CON_REG);
                while (con & OMAP_I2C_CON_STT) {
                        con = omap_i2c_read_reg(omap, OMAP_I2C_CON_REG);

                        /* Let the user know if i2c is in a bad state */
                        if (time_after(jiffies, delay)) {
                                dev_err(omap->dev, "controller timed out "
                                "waiting for start condition to finish\n");
                                return -ETIMEDOUT;
                        }
                        cpu_relax();
                }

                w |= OMAP_I2C_CON_STP;
                w &= ~OMAP_I2C_CON_STT;
                omap_i2c_write_reg(omap, OMAP_I2C_CON_REG, w);
        }

        /*
         * REVISIT: We should abort the transfer on signals, but the bus goes
         * into arbitration and we're currently unable to recover from it.
         */
        if (!polling) {
                timeout = wait_for_completion_timeout(&omap->cmd_complete,
                                                      OMAP_I2C_TIMEOUT);
        } else {
                do {
                        omap_i2c_wait(omap);
                        ret = omap_i2c_xfer_data(omap);
                } while (ret == -EAGAIN);

                timeout = !ret;
        }

        if (timeout == 0) {
                dev_err(omap->dev, "controller timed out\n");
                omap_i2c_reset(omap);
                __omap_i2c_init(omap);
                return -ETIMEDOUT;
        }

        if (likely(!omap->cmd_err))
                return 0;

        /* We have an error */
        if (omap->cmd_err & (OMAP_I2C_STAT_ROVR | OMAP_I2C_STAT_XUDF)) {
                omap_i2c_reset(omap);
                __omap_i2c_init(omap);
                return -EIO;
        }

        if (omap->cmd_err & OMAP_I2C_STAT_AL)
                return -EAGAIN;

        if (omap->cmd_err & OMAP_I2C_STAT_NACK) {
                if (msg->flags & I2C_M_IGNORE_NAK)
                        return 0;

                w = omap_i2c_read_reg(omap, OMAP_I2C_CON_REG);
                w |= OMAP_I2C_CON_STP;
                omap_i2c_write_reg(omap, OMAP_I2C_CON_REG, w);
                return -EREMOTEIO;
        }
        return -EIO;
}


/*
 * Prepare controller for a transaction and call omap_i2c_xfer_msg
 * to do the work during IRQ processing.
 */
static int
omap_i2c_xfer_common(struct i2c_adapter *adap, struct i2c_msg msgs[], int num,
                     bool polling)
{
        struct omap_i2c_dev *omap = i2c_get_adapdata(adap);
        int i;
        int r;

        r = pm_runtime_get_sync(omap->dev);
        if (r < 0)
                goto out;

        r = omap_i2c_wait_for_bb_valid(omap);
        if (r < 0)
                goto out;

        r = omap_i2c_wait_for_bb(omap);
        if (r < 0)
                goto out;

        if (omap->set_mpu_wkup_lat != NULL)
                omap->set_mpu_wkup_lat(omap->dev, omap->latency);

        for (i = 0; i < num; i++) {
                r = omap_i2c_xfer_msg(adap, &msgs[i], (i == (num - 1)),
                                      polling);
                if (r != 0)
                        break;
        }

        if (r == 0)
                r = num;

        omap_i2c_wait_for_bb(omap);

        if (omap->set_mpu_wkup_lat != NULL)
                omap->set_mpu_wkup_lat(omap->dev, -1);

out:
        pm_runtime_mark_last_busy(omap->dev);
        pm_runtime_put_autosuspend(omap->dev);
        return r;
}

static int
omap_i2c_xfer_irq(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
{
        return omap_i2c_xfer_common(adap, msgs, num, false);
}

static int
omap_i2c_xfer_polling(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
{
        return omap_i2c_xfer_common(adap, msgs, num, true);
}

static u32
omap_i2c_func(struct i2c_adapter *adap)
{
        return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK) |
               I2C_FUNC_PROTOCOL_MANGLING;
}

static inline void
omap_i2c_complete_cmd(struct omap_i2c_dev *omap, u16 err)
{
        omap->cmd_err |= err;
        complete(&omap->cmd_complete);
}

static inline void
omap_i2c_ack_stat(struct omap_i2c_dev *omap, u16 stat)
{
        omap_i2c_write_reg(omap, OMAP_I2C_STAT_REG, stat);
}

static inline void i2c_omap_errata_i207(struct omap_i2c_dev *omap, u16 stat)
{
        /*
         * I2C Errata(Errata Nos. OMAP2: 1.67, OMAP3: 1.8)
         * Not applicable for OMAP4.
         * Under certain rare conditions, RDR could be set again
         * when the bus is busy, then ignore the interrupt and
         * clear the interrupt.
         */
        if (stat & OMAP_I2C_STAT_RDR) {
                /* Step 1: If RDR is set, clear it */
                omap_i2c_ack_stat(omap, OMAP_I2C_STAT_RDR);

                /* Step 2: */
                if (!(omap_i2c_read_reg(omap, OMAP_I2C_STAT_REG)
                                                & OMAP_I2C_STAT_BB)) {

                        /* Step 3: */
                        if (omap_i2c_read_reg(omap, OMAP_I2C_STAT_REG)
                                                & OMAP_I2C_STAT_RDR) {
                                omap_i2c_ack_stat(omap, OMAP_I2C_STAT_RDR);
                                dev_dbg(omap->dev, "RDR when bus is busy.\n");
                        }

                }
        }
}

/* rev1 devices are apparently only on some 15xx */
#ifdef CONFIG_ARCH_OMAP15XX

static irqreturn_t
omap_i2c_omap1_isr(int this_irq, void *dev_id)
{
        struct omap_i2c_dev *omap = dev_id;
        u16 iv, w;

        if (pm_runtime_suspended(omap->dev))
                return IRQ_NONE;

        iv = omap_i2c_read_reg(omap, OMAP_I2C_IV_REG);
        switch (iv) {
        case 0x00:      /* None */
                break;
        case 0x01:      /* Arbitration lost */
                dev_err(omap->dev, "Arbitration lost\n");
                omap_i2c_complete_cmd(omap, OMAP_I2C_STAT_AL);
                break;
        case 0x02:      /* No acknowledgement */
                omap_i2c_complete_cmd(omap, OMAP_I2C_STAT_NACK);
                omap_i2c_write_reg(omap, OMAP_I2C_CON_REG, OMAP_I2C_CON_STP);
                break;
        case 0x03:      /* Register access ready */
                omap_i2c_complete_cmd(omap, 0);
                break;
        case 0x04:      /* Receive data ready */
                if (omap->buf_len) {
                        w = omap_i2c_read_reg(omap, OMAP_I2C_DATA_REG);
                        *omap->buf++ = w;
                        omap->buf_len--;
                        if (omap->buf_len) {
                                *omap->buf++ = w >> 8;
                                omap->buf_len--;
                        }
                } else
                        dev_err(omap->dev, "RRDY IRQ while no data requested\n");
                break;
        case 0x05:      /* Transmit data ready */
                if (omap->buf_len) {
                        w = *omap->buf++;
                        omap->buf_len--;
                        if (omap->buf_len) {
                                w |= *omap->buf++ << 8;
                                omap->buf_len--;
                        }
                        omap_i2c_write_reg(omap, OMAP_I2C_DATA_REG, w);
                } else
                        dev_err(omap->dev, "XRDY IRQ while no data to send\n");
                break;
        default:
                return IRQ_NONE;
        }

        return IRQ_HANDLED;
}
#else
#define omap_i2c_omap1_isr              NULL
#endif

/*
 * OMAP3430 Errata i462: When an XRDY/XDR is hit, wait for XUDF before writing
 * data to DATA_REG. Otherwise some data bytes can be lost while transferring
 * them from the memory to the I2C interface.
 */
static int errata_omap3_i462(struct omap_i2c_dev *omap)
{
        unsigned long timeout = 10000;
        u16 stat;

        do {
                stat = omap_i2c_read_reg(omap, OMAP_I2C_STAT_REG);
                if (stat & OMAP_I2C_STAT_XUDF)
                        break;

                if (stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) {
                        omap_i2c_ack_stat(omap, (OMAP_I2C_STAT_XRDY |
                                                        OMAP_I2C_STAT_XDR));
                        if (stat & OMAP_I2C_STAT_NACK) {
                                omap->cmd_err |= OMAP_I2C_STAT_NACK;
                                omap_i2c_ack_stat(omap, OMAP_I2C_STAT_NACK);
                        }

                        if (stat & OMAP_I2C_STAT_AL) {
                                dev_err(omap->dev, "Arbitration lost\n");
                                omap->cmd_err |= OMAP_I2C_STAT_AL;
                                omap_i2c_ack_stat(omap, OMAP_I2C_STAT_AL);
                        }

                        return -EIO;
                }

                cpu_relax();
        } while (--timeout);

        if (!timeout) {
                dev_err(omap->dev, "timeout waiting on XUDF bit\n");
                return 0;
        }

        return 0;
}

static void omap_i2c_receive_data(struct omap_i2c_dev *omap, u8 num_bytes,
                bool is_rdr)

{
        u16             w;

        while (num_bytes--) {
                w = omap_i2c_read_reg(omap, OMAP_I2C_DATA_REG);
                *omap->buf++ = w;
                omap->buf_len--;

                /*
                 * Data reg in 2430, omap3 and
                 * omap4 is 8 bit wide
                 */
                if (omap->flags & OMAP_I2C_FLAG_16BIT_DATA_REG) {
                        *omap->buf++ = w >> 8;
                        omap->buf_len--;
                }
        }
}

static int omap_i2c_transmit_data(struct omap_i2c_dev *omap, u8 num_bytes,
                bool is_xdr)
{
        u16             w;

        while (num_bytes--) {
                w = *omap->buf++;
                omap->buf_len--;

                /*
                 * Data reg in 2430, omap3 and
                 * omap4 is 8 bit wide
                 */
                if (omap->flags & OMAP_I2C_FLAG_16BIT_DATA_REG) {
                        w |= *omap->buf++ << 8;
                        omap->buf_len--;
                }

                if (omap->errata & I2C_OMAP_ERRATA_I462) {
                        int ret;

                        ret = errata_omap3_i462(omap);
                        if (ret < 0)
                                return ret;
                }

                omap_i2c_write_reg(omap, OMAP_I2C_DATA_REG, w);
        }

        return 0;
}

static irqreturn_t
omap_i2c_isr(int irq, void *dev_id)
{
        struct omap_i2c_dev *omap = dev_id;
        irqreturn_t ret = IRQ_HANDLED;
        u16 mask;
        u16 stat;

        stat = omap_i2c_read_reg(omap, OMAP_I2C_STAT_REG);
        mask = omap_i2c_read_reg(omap, OMAP_I2C_IE_REG);

        if (stat & mask)
                ret = IRQ_WAKE_THREAD;

        return ret;
}

static int omap_i2c_xfer_data(struct omap_i2c_dev *omap)
{
        u16 bits;
        u16 stat;
        int err = 0, count = 0;

        do {
                bits = omap_i2c_read_reg(omap, OMAP_I2C_IE_REG);
                stat = omap_i2c_read_reg(omap, OMAP_I2C_STAT_REG);
                stat &= bits;

                /* If we're in receiver mode, ignore XDR/XRDY */
                if (omap->receiver)
                        stat &= ~(OMAP_I2C_STAT_XDR | OMAP_I2C_STAT_XRDY);
                else
                        stat &= ~(OMAP_I2C_STAT_RDR | OMAP_I2C_STAT_RRDY);

                if (!stat) {
                        /* my work here is done */
                        err = -EAGAIN;
                        break;
                }

                dev_dbg(omap->dev, "IRQ (ISR = 0x%04x)\n", stat);
                if (count++ == 100) {
                        dev_warn(omap->dev, "Too much work in one IRQ\n");
                        break;
                }

                if (stat & OMAP_I2C_STAT_NACK) {
                        err |= OMAP_I2C_STAT_NACK;
                        omap_i2c_ack_stat(omap, OMAP_I2C_STAT_NACK);
                }

                if (stat & OMAP_I2C_STAT_AL) {
                        dev_err(omap->dev, "Arbitration lost\n");
                        err |= OMAP_I2C_STAT_AL;
                        omap_i2c_ack_stat(omap, OMAP_I2C_STAT_AL);
                }

                /*
                 * ProDB0017052: Clear ARDY bit twice
                 */
                if (stat & OMAP_I2C_STAT_ARDY)
                        omap_i2c_ack_stat(omap, OMAP_I2C_STAT_ARDY);

                if (stat & (OMAP_I2C_STAT_ARDY | OMAP_I2C_STAT_NACK |
                                        OMAP_I2C_STAT_AL)) {
                        omap_i2c_ack_stat(omap, (OMAP_I2C_STAT_RRDY |
                                                OMAP_I2C_STAT_RDR |
                                                OMAP_I2C_STAT_XRDY |
                                                OMAP_I2C_STAT_XDR |
                                                OMAP_I2C_STAT_ARDY));
                        break;
                }

                if (stat & OMAP_I2C_STAT_RDR) {
                        u8 num_bytes = 1;

                        if (omap->fifo_size)
                                num_bytes = omap->buf_len;

                        if (omap->errata & I2C_OMAP_ERRATA_I207) {
                                i2c_omap_errata_i207(omap, stat);
                                num_bytes = (omap_i2c_read_reg(omap,
                                        OMAP_I2C_BUFSTAT_REG) >> 8) & 0x3F;
                        }

                        omap_i2c_receive_data(omap, num_bytes, true);
                        omap_i2c_ack_stat(omap, OMAP_I2C_STAT_RDR);
                        continue;
                }

                if (stat & OMAP_I2C_STAT_RRDY) {
                        u8 num_bytes = 1;

                        if (omap->threshold)
                                num_bytes = omap->threshold;

                        omap_i2c_receive_data(omap, num_bytes, false);
                        omap_i2c_ack_stat(omap, OMAP_I2C_STAT_RRDY);
                        continue;
                }

                if (stat & OMAP_I2C_STAT_XDR) {
                        u8 num_bytes = 1;
                        int ret;

                        if (omap->fifo_size)
                                num_bytes = omap->buf_len;

                        ret = omap_i2c_transmit_data(omap, num_bytes, true);
                        if (ret < 0)
                                break;

                        omap_i2c_ack_stat(omap, OMAP_I2C_STAT_XDR);
                        continue;
                }

                if (stat & OMAP_I2C_STAT_XRDY) {
                        u8 num_bytes = 1;
                        int ret;

                        if (omap->threshold)
                                num_bytes = omap->threshold;

                        ret = omap_i2c_transmit_data(omap, num_bytes, false);
                        if (ret < 0)
                                break;

                        omap_i2c_ack_stat(omap, OMAP_I2C_STAT_XRDY);
                        continue;
                }

                if (stat & OMAP_I2C_STAT_ROVR) {
                        dev_err(omap->dev, "Receive overrun\n");
                        err |= OMAP_I2C_STAT_ROVR;
                        omap_i2c_ack_stat(omap, OMAP_I2C_STAT_ROVR);
                        break;
                }

                if (stat & OMAP_I2C_STAT_XUDF) {
                        dev_err(omap->dev, "Transmit underflow\n");
                        err |= OMAP_I2C_STAT_XUDF;
                        omap_i2c_ack_stat(omap, OMAP_I2C_STAT_XUDF);
                        break;
                }
        } while (stat);

        return err;
}

static irqreturn_t
omap_i2c_isr_thread(int this_irq, void *dev_id)
{
        int ret;
        struct omap_i2c_dev *omap = dev_id;

        ret = omap_i2c_xfer_data(omap);
        if (ret != -EAGAIN)
                omap_i2c_complete_cmd(omap, ret);

        return IRQ_HANDLED;
}

static const struct i2c_algorithm omap_i2c_algo = {
        .master_xfer    = omap_i2c_xfer_irq,
        .master_xfer_atomic     = omap_i2c_xfer_polling,
        .functionality  = omap_i2c_func,
};

static const struct i2c_adapter_quirks omap_i2c_quirks = {
        .flags = I2C_AQ_NO_ZERO_LEN,
};

#ifdef CONFIG_OF
static struct omap_i2c_bus_platform_data omap2420_pdata = {
        .rev = OMAP_I2C_IP_VERSION_1,
        .flags = OMAP_I2C_FLAG_NO_FIFO |
                        OMAP_I2C_FLAG_SIMPLE_CLOCK |
                        OMAP_I2C_FLAG_16BIT_DATA_REG |
                        OMAP_I2C_FLAG_BUS_SHIFT_2,
};

static struct omap_i2c_bus_platform_data omap2430_pdata = {
        .rev = OMAP_I2C_IP_VERSION_1,
        .flags = OMAP_I2C_FLAG_BUS_SHIFT_2 |
                        OMAP_I2C_FLAG_FORCE_19200_INT_CLK,
};

static struct omap_i2c_bus_platform_data omap3_pdata = {
        .rev = OMAP_I2C_IP_VERSION_1,
        .flags = OMAP_I2C_FLAG_BUS_SHIFT_2,
};

static struct omap_i2c_bus_platform_data omap4_pdata = {
        .rev = OMAP_I2C_IP_VERSION_2,
};

static const struct of_device_id omap_i2c_of_match[] = {
        {
                .compatible = "ti,omap4-i2c",
                .data = &omap4_pdata,
        },
        {
                .compatible = "ti,omap3-i2c",
                .data = &omap3_pdata,
        },
        {
                .compatible = "ti,omap2430-i2c",
                .data = &omap2430_pdata,
        },
        {
                .compatible = "ti,omap2420-i2c",
                .data = &omap2420_pdata,
        },
        { },
};
MODULE_DEVICE_TABLE(of, omap_i2c_of_match);
#endif

#define OMAP_I2C_SCHEME(rev)            ((rev & 0xc000) >> 14)

#define OMAP_I2C_REV_SCHEME_0_MAJOR(rev) (rev >> 4)
#define OMAP_I2C_REV_SCHEME_0_MINOR(rev) (rev & 0xf)

#define OMAP_I2C_REV_SCHEME_1_MAJOR(rev) ((rev & 0x0700) >> 7)
#define OMAP_I2C_REV_SCHEME_1_MINOR(rev) (rev & 0x1f)
#define OMAP_I2C_SCHEME_0               0
#define OMAP_I2C_SCHEME_1               1

static int omap_i2c_get_scl(struct i2c_adapter *adap)
{
        struct omap_i2c_dev *dev = i2c_get_adapdata(adap);
        u32 reg;

        reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);

        return reg & OMAP_I2C_SYSTEST_SCL_I_FUNC;
}

static int omap_i2c_get_sda(struct i2c_adapter *adap)
{
        struct omap_i2c_dev *dev = i2c_get_adapdata(adap);
        u32 reg;

        reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);

        return reg & OMAP_I2C_SYSTEST_SDA_I_FUNC;
}

static void omap_i2c_set_scl(struct i2c_adapter *adap, int val)
{
        struct omap_i2c_dev *dev = i2c_get_adapdata(adap);
        u32 reg;

        reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);
        if (val)
                reg |= OMAP_I2C_SYSTEST_SCL_O;
        else
                reg &= ~OMAP_I2C_SYSTEST_SCL_O;
        omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg);
}

static void omap_i2c_prepare_recovery(struct i2c_adapter *adap)
{
        struct omap_i2c_dev *dev = i2c_get_adapdata(adap);
        u32 reg;

        reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);
        /* enable test mode */
        reg |= OMAP_I2C_SYSTEST_ST_EN;
        /* select SDA/SCL IO mode */
        reg |= 3 << OMAP_I2C_SYSTEST_TMODE_SHIFT;
        /* set SCL to high-impedance state (reset value is 0) */
        reg |= OMAP_I2C_SYSTEST_SCL_O;
        /* set SDA to high-impedance state (reset value is 0) */
        reg |= OMAP_I2C_SYSTEST_SDA_O;
        omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg);
}

static void omap_i2c_unprepare_recovery(struct i2c_adapter *adap)
{
        struct omap_i2c_dev *dev = i2c_get_adapdata(adap);
        u32 reg;

        reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);
        /* restore reset values */
        reg &= ~OMAP_I2C_SYSTEST_ST_EN;
        reg &= ~OMAP_I2C_SYSTEST_TMODE_MASK;
        reg &= ~OMAP_I2C_SYSTEST_SCL_O;
        reg &= ~OMAP_I2C_SYSTEST_SDA_O;
        omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg);
}

static struct i2c_bus_recovery_info omap_i2c_bus_recovery_info = {
        .get_scl                = omap_i2c_get_scl,
        .get_sda                = omap_i2c_get_sda,
        .set_scl                = omap_i2c_set_scl,
        .prepare_recovery       = omap_i2c_prepare_recovery,
        .unprepare_recovery     = omap_i2c_unprepare_recovery,
        .recover_bus            = i2c_generic_scl_recovery,
};

static int
omap_i2c_probe(struct platform_device *pdev)
{
        struct omap_i2c_dev     *omap;
        struct i2c_adapter      *adap;
        const struct omap_i2c_bus_platform_data *pdata =
                dev_get_platdata(&pdev->dev);
        struct device_node      *node = pdev->dev.of_node;
        const struct of_device_id *match;
        int irq;
        int r;
        u32 rev;
        u16 minor, major;

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;

        omap = devm_kzalloc(&pdev->dev, sizeof(struct omap_i2c_dev), GFP_KERNEL);
        if (!omap)
                return -ENOMEM;

        omap->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(omap->base))
                return PTR_ERR(omap->base);

        match = of_match_device(of_match_ptr(omap_i2c_of_match), &pdev->dev);
        if (match) {
                u32 freq = I2C_MAX_STANDARD_MODE_FREQ;

                pdata = match->data;
                omap->flags = pdata->flags;

                of_property_read_u32(node, "clock-frequency", &freq);
                /* convert DT freq value in Hz into kHz for speed */
                omap->speed = freq / 1000;
        } else if (pdata != NULL) {
                omap->speed = pdata->clkrate;
                omap->flags = pdata->flags;
                omap->set_mpu_wkup_lat = pdata->set_mpu_wkup_lat;
        }

        omap->dev = &pdev->dev;
        omap->irq = irq;

        platform_set_drvdata(pdev, omap);
        init_completion(&omap->cmd_complete);

        omap->reg_shift = (omap->flags >> OMAP_I2C_FLAG_BUS_SHIFT__SHIFT) & 3;

        pm_runtime_enable(omap->dev);
        pm_runtime_set_autosuspend_delay(omap->dev, OMAP_I2C_PM_TIMEOUT);
        pm_runtime_use_autosuspend(omap->dev);

        r = pm_runtime_resume_and_get(omap->dev);
        if (r < 0)
                goto err_disable_pm;

        /*
         * Read the Rev hi bit-[15:14] ie scheme this is 1 indicates ver2.
         * On omap1/3/2 Offset 4 is IE Reg the bit [15:14] is 0 at reset.
         * Also since the omap_i2c_read_reg uses reg_map_ip_* a
         * readw_relaxed is done.
         */
        rev = readw_relaxed(omap->base + 0x04);

        omap->scheme = OMAP_I2C_SCHEME(rev);
        switch (omap->scheme) {
        case OMAP_I2C_SCHEME_0:
                omap->regs = (u8 *)reg_map_ip_v1;
                omap->rev = omap_i2c_read_reg(omap, OMAP_I2C_REV_REG);
                minor = OMAP_I2C_REV_SCHEME_0_MAJOR(omap->rev);
                major = OMAP_I2C_REV_SCHEME_0_MAJOR(omap->rev);
                break;
        case OMAP_I2C_SCHEME_1:
        default:
                omap->regs = (u8 *)reg_map_ip_v2;
                rev = (rev << 16) |
                        omap_i2c_read_reg(omap, OMAP_I2C_IP_V2_REVNB_LO);
                minor = OMAP_I2C_REV_SCHEME_1_MINOR(rev);
                major = OMAP_I2C_REV_SCHEME_1_MAJOR(rev);
                omap->rev = rev;
        }

        omap->errata = 0;

        if (omap->rev >= OMAP_I2C_REV_ON_2430 &&
                        omap->rev < OMAP_I2C_REV_ON_4430_PLUS)
                omap->errata |= I2C_OMAP_ERRATA_I207;

        if (omap->rev <= OMAP_I2C_REV_ON_3430_3530)
                omap->errata |= I2C_OMAP_ERRATA_I462;

        if (!(omap->flags & OMAP_I2C_FLAG_NO_FIFO)) {
                u16 s;

                /* Set up the fifo size - Get total size */
                s = (omap_i2c_read_reg(omap, OMAP_I2C_BUFSTAT_REG) >> 14) & 0x3;
                omap->fifo_size = 0x8 << s;

                /*
                 * Set up notification threshold as half the total available
                 * size. This is to ensure that we can handle the status on int
                 * call back latencies.
                 */

                omap->fifo_size = (omap->fifo_size / 2);

                if (omap->rev < OMAP_I2C_REV_ON_3630)
                        omap->b_hw = 1; /* Enable hardware fixes */

                /* calculate wakeup latency constraint for MPU */
                if (omap->set_mpu_wkup_lat != NULL)
                        omap->latency = (1000000 * omap->fifo_size) /
                                       (1000 * omap->speed / 8);
        }

        /* reset ASAP, clearing any IRQs */
        omap_i2c_init(omap);

        if (omap->rev < OMAP_I2C_OMAP1_REV_2)
                r = devm_request_irq(&pdev->dev, omap->irq, omap_i2c_omap1_isr,
                                IRQF_NO_SUSPEND, pdev->name, omap);
        else
                r = devm_request_threaded_irq(&pdev->dev, omap->irq,
                                omap_i2c_isr, omap_i2c_isr_thread,
                                IRQF_NO_SUSPEND | IRQF_ONESHOT,
                                pdev->name, omap);

        if (r) {
                dev_err(omap->dev, "failure requesting irq %i\n", omap->irq);
                goto err_unuse_clocks;
        }

        adap = &omap->adapter;
        i2c_set_adapdata(adap, omap);
        adap->owner = THIS_MODULE;
        adap->class = I2C_CLASS_DEPRECATED;
        strlcpy(adap->name, "OMAP I2C adapter", sizeof(adap->name));
        adap->algo = &omap_i2c_algo;
        adap->quirks = &omap_i2c_quirks;
        adap->dev.parent = &pdev->dev;
        adap->dev.of_node = pdev->dev.of_node;
        adap->bus_recovery_info = &omap_i2c_bus_recovery_info;

        /* i2c device drivers may be active on return from add_adapter() */
        adap->nr = pdev->id;
        r = i2c_add_numbered_adapter(adap);
        if (r)
                goto err_unuse_clocks;

        dev_info(omap->dev, "bus %d rev%d.%d at %d kHz\n", adap->nr,
                 major, minor, omap->speed);

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

        return 0;

err_unuse_clocks:
        omap_i2c_write_reg(omap, OMAP_I2C_CON_REG, 0);
        pm_runtime_dont_use_autosuspend(omap->dev);
        pm_runtime_put_sync(omap->dev);
err_disable_pm:
        pm_runtime_disable(&pdev->dev);

        return r;
}

static int omap_i2c_remove(struct platform_device *pdev)
{
        struct omap_i2c_dev     *omap = platform_get_drvdata(pdev);
        int ret;

        i2c_del_adapter(&omap->adapter);
        ret = pm_runtime_resume_and_get(&pdev->dev);
        if (ret < 0)
                return ret;

        omap_i2c_write_reg(omap, OMAP_I2C_CON_REG, 0);
        pm_runtime_dont_use_autosuspend(&pdev->dev);
        pm_runtime_put_sync(&pdev->dev);
        pm_runtime_disable(&pdev->dev);
        return 0;
}

static int __maybe_unused omap_i2c_runtime_suspend(struct device *dev)
{
        struct omap_i2c_dev *omap = dev_get_drvdata(dev);

        omap->iestate = omap_i2c_read_reg(omap, OMAP_I2C_IE_REG);

        if (omap->scheme == OMAP_I2C_SCHEME_0)
                omap_i2c_write_reg(omap, OMAP_I2C_IE_REG, 0);
        else
                omap_i2c_write_reg(omap, OMAP_I2C_IP_V2_IRQENABLE_CLR,
                                   OMAP_I2C_IP_V2_INTERRUPTS_MASK);

        if (omap->rev < OMAP_I2C_OMAP1_REV_2) {
                omap_i2c_read_reg(omap, OMAP_I2C_IV_REG); /* Read clears */
        } else {
                omap_i2c_write_reg(omap, OMAP_I2C_STAT_REG, omap->iestate);

                /* Flush posted write */
                omap_i2c_read_reg(omap, OMAP_I2C_STAT_REG);
        }

        pinctrl_pm_select_sleep_state(dev);

        return 0;
}

static int __maybe_unused omap_i2c_runtime_resume(struct device *dev)
{
        struct omap_i2c_dev *omap = dev_get_drvdata(dev);

        pinctrl_pm_select_default_state(dev);

        if (!omap->regs)
                return 0;

        __omap_i2c_init(omap);

        return 0;
}

static const struct dev_pm_ops omap_i2c_pm_ops = {
        SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
                                      pm_runtime_force_resume)
        SET_RUNTIME_PM_OPS(omap_i2c_runtime_suspend,
                           omap_i2c_runtime_resume, NULL)
};

static struct platform_driver omap_i2c_driver = {
        .probe          = omap_i2c_probe,
        .remove         = omap_i2c_remove,
        .driver         = {
                .name   = "omap_i2c",
                .pm     = &omap_i2c_pm_ops,
                .of_match_table = of_match_ptr(omap_i2c_of_match),
        },
};

/* I2C may be needed to bring up other drivers */
static int __init
omap_i2c_init_driver(void)
{
        return platform_driver_register(&omap_i2c_driver);
}
subsys_initcall(omap_i2c_init_driver);

static void __exit omap_i2c_exit_driver(void)
{
        platform_driver_unregister(&omap_i2c_driver);
}
module_exit(omap_i2c_exit_driver);

MODULE_AUTHOR("MontaVista Software, Inc. (and others)");
MODULE_DESCRIPTION("TI OMAP I2C bus adapter");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:omap_i2c");