/*
 * Basic I2C functions
 *
 * Copyright (c) 2004 Texas Instruments
 *
 * This package is free software;  you can redistribute it and/or
 * modify it under the terms of the license found in the file
 * named COPYING that should have accompanied this file.
 *
 * THIS PACKAGE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Author: Jian Zhang jzhang@ti.com, Texas Instruments
 *
 * Copyright (c) 2003 Wolfgang Denk, wd@denx.de
 * Rewritten to fit into the current U-Boot framework
 *
 * Adapted for OMAP2420 I2C, r-woodruff2@ti.com
 *
 * Copyright (c) 2013 Lubomir Popov <lpopov@mm-sol.com>, MM Solutions
 * New i2c_read, i2c_write and i2c_probe functions, tested on OMAP4
 * (4430/60/70), OMAP5 (5430) and AM335X (3359); should work on older
 * OMAPs and derivatives as well. The only anticipated exception would
 * be the OMAP2420, which shall require driver modification.
 * - Rewritten i2c_read to operate correctly with all types of chips
 *   (old function could not read consistent data from some I2C slaves).
 * - Optimized i2c_write.
 * - New i2c_probe, performs write access vs read. The old probe could
 *   hang the system under certain conditions (e.g. unconfigured pads).
 * - The read/write/probe functions try to identify unconfigured bus.
 * - Status functions now read irqstatus_raw as per TRM guidelines
 *   (except for OMAP243X and OMAP34XX).
 * - Driver now supports up to I2C5 (OMAP5).
 *
 * Copyright (c) 2014 Hannes Schmelzer <oe5hpm@oevsv.at>, B&R
 * - Added support for set_speed
 *
 */

#include <common.h>
#include <dm.h>
#include <i2c.h>
#include <log.h>
#include <linux/delay.h>

#include <asm/io.h>
#include <asm/omap_i2c.h>

/*
 * Provide access to architecture-specific I2C header files for platforms
 * that are NOT yet solely relying on CONFIG_DM_I2C, CONFIG_OF_CONTROL, and
 * the defaults provided in 'omap24xx_i2c.h' for all U-Boot stages where I2C
 * access is desired.
 */
#ifndef CONFIG_ARCH_K3
#include <asm/arch/i2c.h>
#endif

#include "omap24xx_i2c.h"

#define I2C_TIMEOUT     1000

/* Absolutely safe for status update at 100 kHz I2C: */
#define I2C_WAIT        200

enum {
        OMAP_I2C_REV_REG = 0,           /* Only on IP V1 (OMAP34XX) */
        OMAP_I2C_IE_REG,                /* Only on IP V1 (OMAP34XX) */
        OMAP_I2C_STAT_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 IP V2 (OMAP4430, etc.) */
        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,
};

static const u8 __maybe_unused reg_map_ip_v1[] = {
        [OMAP_I2C_REV_REG] = 0x00,
        [OMAP_I2C_IE_REG] = 0x04,
        [OMAP_I2C_STAT_REG] = 0x08,
        [OMAP_I2C_WE_REG] = 0x0c,
        [OMAP_I2C_SYSS_REG] = 0x10,
        [OMAP_I2C_BUF_REG] = 0x14,
        [OMAP_I2C_CNT_REG] = 0x18,
        [OMAP_I2C_DATA_REG] = 0x1c,
        [OMAP_I2C_SYSC_REG] = 0x20,
        [OMAP_I2C_CON_REG] = 0x24,
        [OMAP_I2C_OA_REG] = 0x28,
        [OMAP_I2C_SA_REG] = 0x2c,
        [OMAP_I2C_PSC_REG] = 0x30,
        [OMAP_I2C_SCLL_REG] = 0x34,
        [OMAP_I2C_SCLH_REG] = 0x38,
        [OMAP_I2C_SYSTEST_REG] = 0x3c,
        [OMAP_I2C_BUFSTAT_REG] = 0x40,
};

static const u8 __maybe_unused reg_map_ip_v2[] = {
        [OMAP_I2C_STAT_REG] = 0x28,
        [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,
};

struct omap_i2c {
        struct udevice *clk;
        int ip_rev;
        struct i2c *regs;
        unsigned int speed;
        int waitdelay;
        int clk_id;
};

static inline const u8 *omap_i2c_get_ip_reg_map(int ip_rev)
{
        switch (ip_rev) {
        case OMAP_I2C_REV_V1:
                return reg_map_ip_v1;
        case OMAP_I2C_REV_V2:
                /* Fall through... */
        default:
                return reg_map_ip_v2;
        }
}

static inline void omap_i2c_write_reg(void __iomem *base, int ip_rev,
                                      u16 val, int reg)
{
        writew(val, base + omap_i2c_get_ip_reg_map(ip_rev)[reg]);
}

static inline u16 omap_i2c_read_reg(void __iomem *base, int ip_rev, int reg)
{
        return readw(base + omap_i2c_get_ip_reg_map(ip_rev)[reg]);
}

static int omap24_i2c_findpsc(u32 *pscl, u32 *psch, uint speed)
{
        unsigned long internal_clk = 0, fclk;
        unsigned int prescaler;

        /*
         * This method is only called for Standard and Fast Mode speeds
         *
         * For some TI SoCs it is explicitly written in TRM (e,g, SPRUHZ6G,
         * page 5685, Table 24-7)
         * that the internal I2C clock (after prescaler) should be between
         * 7-12 MHz (at least for Fast Mode (FS)).
         *
         * Such approach is used in v4.9 Linux kernel in:
         * ./drivers/i2c/busses/i2c-omap.c (omap_i2c_init function).
         */

        speed /= 1000; /* convert speed to kHz */

        if (speed > 100)
                internal_clk = 9600;
        else
                internal_clk = 4000;

        fclk = I2C_IP_CLK / 1000;
        prescaler = fclk / internal_clk;
        prescaler = prescaler - 1;

        if (speed > 100) {
                unsigned long scl;

                /* Fast mode */
                scl = internal_clk / speed;
                *pscl = scl - (scl / 3) - I2C_FASTSPEED_SCLL_TRIM;
                *psch = (scl / 3) - I2C_FASTSPEED_SCLH_TRIM;
        } else {
                /* Standard mode */
                *pscl = internal_clk / (speed * 2) - I2C_FASTSPEED_SCLL_TRIM;
                *psch = internal_clk / (speed * 2) - I2C_FASTSPEED_SCLH_TRIM;
        }

        debug("%s: speed [kHz]: %d psc: 0x%x sscl: 0x%x ssch: 0x%x\n",
              __func__, speed, prescaler, *pscl, *psch);

        if (*pscl <= 0 || *psch <= 0 || prescaler <= 0)
                return -EINVAL;

        return prescaler;
}

/*
 * Wait for the bus to be free by checking the Bus Busy (BB)
 * bit to become clear
 */
static int wait_for_bb(void __iomem *i2c_base, int ip_rev, int waitdelay)
{
        int timeout = I2C_TIMEOUT;
        int irq_stat_reg;
        u16 stat;

        irq_stat_reg = (ip_rev == OMAP_I2C_REV_V1) ?
                       OMAP_I2C_STAT_REG : OMAP_I2C_IP_V2_IRQSTATUS_RAW;

        /* clear current interrupts */
        omap_i2c_write_reg(i2c_base, ip_rev, 0xFFFF, OMAP_I2C_STAT_REG);

        while ((stat = omap_i2c_read_reg(i2c_base, ip_rev, irq_stat_reg) &
                I2C_STAT_BB) && timeout--) {
                omap_i2c_write_reg(i2c_base, ip_rev, stat, OMAP_I2C_STAT_REG);
                udelay(waitdelay);
        }

        if (timeout <= 0) {
                printf("Timed out in %s: status=%04x\n", __func__, stat);
                return 1;
        }

        /* clear delayed stuff */
        omap_i2c_write_reg(i2c_base, ip_rev, 0xFFFF, OMAP_I2C_STAT_REG);
        return 0;
}

/*
 * Wait for the I2C controller to complete current action
 * and update status
 */
static u16 wait_for_event(void __iomem *i2c_base, int ip_rev, int waitdelay)
{
        u16 status;
        int timeout = I2C_TIMEOUT;
        int irq_stat_reg;

        irq_stat_reg = (ip_rev == OMAP_I2C_REV_V1) ?
                       OMAP_I2C_STAT_REG : OMAP_I2C_IP_V2_IRQSTATUS_RAW;
        do {
                udelay(waitdelay);
                status = omap_i2c_read_reg(i2c_base, ip_rev, irq_stat_reg);
        } while (!(status &
                   (I2C_STAT_ROVR | I2C_STAT_XUDF | I2C_STAT_XRDY |
                    I2C_STAT_RRDY | I2C_STAT_ARDY | I2C_STAT_NACK |
                    I2C_STAT_AL)) && timeout--);

        if (timeout <= 0) {
                printf("Timed out in %s: status=%04x\n", __func__, status);
                /*
                 * If status is still 0 here, probably the bus pads have
                 * not been configured for I2C, and/or pull-ups are missing.
                 */
                printf("Check if pads/pull-ups of bus are properly configured\n");
                omap_i2c_write_reg(i2c_base, ip_rev, 0xFFFF, OMAP_I2C_STAT_REG);
                status = 0;
        }

        return status;
}

static void flush_fifo(void __iomem *i2c_base, int ip_rev)
{
        u16 stat;

        /*
         * note: if you try and read data when its not there or ready
         * you get a bus error
         */
        while (1) {
                stat = omap_i2c_read_reg(i2c_base, ip_rev, OMAP_I2C_STAT_REG);
                if (stat == I2C_STAT_RRDY) {
                        omap_i2c_read_reg(i2c_base, ip_rev, OMAP_I2C_DATA_REG);
                        omap_i2c_write_reg(i2c_base, ip_rev,
                                           I2C_STAT_RRDY, OMAP_I2C_STAT_REG);
                        udelay(1000);
                } else
                        break;
        }
}

static int __omap24_i2c_setspeed(void __iomem *i2c_base, int ip_rev, uint speed,
                                 int *waitdelay)
{
        int psc, fsscll = 0, fssclh = 0;
        int hsscll = 0, hssclh = 0;
        u32 scll = 0, sclh = 0;

        if (speed >= I2C_SPEED_HIGH_RATE) {
                /* High speed */
                psc = I2C_IP_CLK / I2C_INTERNAL_SAMPLING_CLK;
                psc -= 1;
                if (psc < I2C_PSC_MIN) {
                        printf("Error : I2C unsupported prescaler %d\n", psc);
                        return -1;
                }

                /* For first phase of HS mode */
                fsscll = I2C_INTERNAL_SAMPLING_CLK / (2 * speed);

                fssclh = fsscll;

                fsscll -= I2C_HIGHSPEED_PHASE_ONE_SCLL_TRIM;
                fssclh -= I2C_HIGHSPEED_PHASE_ONE_SCLH_TRIM;
                if (((fsscll < 0) || (fssclh < 0)) ||
                    ((fsscll > 255) || (fssclh > 255))) {
                        puts("Error : I2C initializing first phase clock\n");
                        return -1;
                }

                /* For second phase of HS mode */
                hsscll = hssclh = I2C_INTERNAL_SAMPLING_CLK / (2 * speed);

                hsscll -= I2C_HIGHSPEED_PHASE_TWO_SCLL_TRIM;
                hssclh -= I2C_HIGHSPEED_PHASE_TWO_SCLH_TRIM;
                if (((fsscll < 0) || (fssclh < 0)) ||
                    ((fsscll > 255) || (fssclh > 255))) {
                        puts("Error : I2C initializing second phase clock\n");
                        return -1;
                }

                scll = (unsigned int)hsscll << 8 | (unsigned int)fsscll;
                sclh = (unsigned int)hssclh << 8 | (unsigned int)fssclh;

        } else {
                /* Standard and fast speed */
                psc = omap24_i2c_findpsc(&scll, &sclh, speed);
                if (0 > psc) {
                        puts("Error : I2C initializing clock\n");
                        return -1;
                }
        }

        /* wait for 20 clkperiods */
        *waitdelay = (10000000 / speed) * 2;

        omap_i2c_write_reg(i2c_base, ip_rev, 0,  OMAP_I2C_CON_REG);
        omap_i2c_write_reg(i2c_base, ip_rev, psc, OMAP_I2C_PSC_REG);
        omap_i2c_write_reg(i2c_base, ip_rev, scll, OMAP_I2C_SCLL_REG);
        omap_i2c_write_reg(i2c_base, ip_rev, sclh, OMAP_I2C_SCLH_REG);
        omap_i2c_write_reg(i2c_base, ip_rev, I2C_CON_EN, OMAP_I2C_CON_REG);

        /* clear all pending status */
        omap_i2c_write_reg(i2c_base, ip_rev, 0xFFFF, OMAP_I2C_STAT_REG);

        return 0;
}

static void omap24_i2c_deblock(void __iomem *i2c_base, int ip_rev)
{
        int i;
        u16 systest;
        u16 orgsystest;

        /* set test mode ST_EN = 1 */
        orgsystest = omap_i2c_read_reg(i2c_base, ip_rev, OMAP_I2C_SYSTEST_REG);
        systest = orgsystest;

        /* enable testmode */
        systest |= I2C_SYSTEST_ST_EN;
        omap_i2c_write_reg(i2c_base, ip_rev, systest, OMAP_I2C_SYSTEST_REG);
        systest &= ~I2C_SYSTEST_TMODE_MASK;
        systest |= 3 << I2C_SYSTEST_TMODE_SHIFT;
        omap_i2c_write_reg(i2c_base, ip_rev, systest, OMAP_I2C_SYSTEST_REG);

        /* set SCL, SDA  = 1 */
        systest |= I2C_SYSTEST_SCL_O | I2C_SYSTEST_SDA_O;
        omap_i2c_write_reg(i2c_base, ip_rev, systest, OMAP_I2C_SYSTEST_REG);
        udelay(10);

        /* toggle scl 9 clocks */
        for (i = 0; i < 9; i++) {
                /* SCL = 0 */
                systest &= ~I2C_SYSTEST_SCL_O;
                omap_i2c_write_reg(i2c_base, ip_rev,
                                   systest, OMAP_I2C_SYSTEST_REG);
                udelay(10);
                /* SCL = 1 */
                systest |= I2C_SYSTEST_SCL_O;
                omap_i2c_write_reg(i2c_base, ip_rev,
                                   systest, OMAP_I2C_SYSTEST_REG);
                udelay(10);
        }

        /* send stop */
        systest &= ~I2C_SYSTEST_SDA_O;
        omap_i2c_write_reg(i2c_base, ip_rev, systest, OMAP_I2C_SYSTEST_REG);
        udelay(10);
        systest |= I2C_SYSTEST_SCL_O | I2C_SYSTEST_SDA_O;
        omap_i2c_write_reg(i2c_base, ip_rev, systest, OMAP_I2C_SYSTEST_REG);
        udelay(10);

        /* restore original mode */
        omap_i2c_write_reg(i2c_base, ip_rev, orgsystest, OMAP_I2C_SYSTEST_REG);
}

static void __omap24_i2c_init(void __iomem *i2c_base, int ip_rev, int speed,
                              int slaveadd, int *waitdelay)
{
        int timeout = I2C_TIMEOUT;
        int deblock = 1;

retry:
        if (omap_i2c_read_reg(i2c_base, ip_rev, OMAP_I2C_CON_REG) &
            I2C_CON_EN) {
                omap_i2c_write_reg(i2c_base, ip_rev, 0, OMAP_I2C_CON_REG);
                udelay(50000);
        }

        /* for ES2 after soft reset */
        omap_i2c_write_reg(i2c_base, ip_rev, 0x2, OMAP_I2C_SYSC_REG);
        udelay(1000);

        omap_i2c_write_reg(i2c_base, ip_rev, I2C_CON_EN, OMAP_I2C_CON_REG);
        while (!(omap_i2c_read_reg(i2c_base, ip_rev, OMAP_I2C_SYSS_REG) &
                 I2C_SYSS_RDONE) && timeout--) {
                if (timeout <= 0) {
                        puts("ERROR: Timeout in soft-reset\n");
                        return;
                }
                udelay(1000);
        }

        if (__omap24_i2c_setspeed(i2c_base, ip_rev, speed, waitdelay)) {
                printf("ERROR: failed to setup I2C bus-speed!\n");
                return;
        }

        /* own address */
        omap_i2c_write_reg(i2c_base, ip_rev, slaveadd, OMAP_I2C_OA_REG);

        if (ip_rev == OMAP_I2C_REV_V1) {
                /*
                 * Have to enable interrupts for OMAP2/3, these IPs don't have
                 * an 'irqstatus_raw' register and we shall have to poll 'stat'
                 */
                omap_i2c_write_reg(i2c_base, ip_rev, I2C_IE_XRDY_IE |
                                   I2C_IE_RRDY_IE | I2C_IE_ARDY_IE |
                                   I2C_IE_NACK_IE | I2C_IE_AL_IE,
                                   OMAP_I2C_IE_REG);
        }

        udelay(1000);
        flush_fifo(i2c_base, ip_rev);
        omap_i2c_write_reg(i2c_base, ip_rev, 0xFFFF, OMAP_I2C_STAT_REG);

        /* Handle possible failed I2C state */
        if (wait_for_bb(i2c_base, ip_rev, *waitdelay))
                if (deblock == 1) {
                        omap24_i2c_deblock(i2c_base, ip_rev);
                        deblock = 0;
                        goto retry;
                }
}

/*
 * i2c_probe: Use write access. Allows to identify addresses that are
 *            write-only (like the config register of dual-port EEPROMs)
 */
static int __omap24_i2c_probe(void __iomem *i2c_base, int ip_rev, int waitdelay,
                              uchar chip)
{
        u16 status;
        int res = 1; /* default = fail */

        if (chip == omap_i2c_read_reg(i2c_base, ip_rev, OMAP_I2C_OA_REG))
                return res;

        /* Wait until bus is free */
        if (wait_for_bb(i2c_base, ip_rev, waitdelay))
                return res;

        /* No data transfer, slave addr only */
        omap_i2c_write_reg(i2c_base, ip_rev, chip, OMAP_I2C_SA_REG);

        /* Stop bit needed here */
        omap_i2c_write_reg(i2c_base, ip_rev, I2C_CON_EN | I2C_CON_MST |
                           I2C_CON_STT | I2C_CON_TRX | I2C_CON_STP,
                           OMAP_I2C_CON_REG);

        status = wait_for_event(i2c_base, ip_rev, waitdelay);

        if ((status & ~I2C_STAT_XRDY) == 0 || (status & I2C_STAT_AL)) {
                /*
                 * With current high-level command implementation, notifying
                 * the user shall flood the console with 127 messages. If
                 * silent exit is desired upon unconfigured bus, remove the
                 * following 'if' section:
                 */
                if (status == I2C_STAT_XRDY)
                        printf("i2c_probe: pads on bus probably not configured (status=0x%x)\n",
                               status);

                goto pr_exit;
        }

        /* Check for ACK (!NAK) */
        if (!(status & I2C_STAT_NACK)) {
                res = 0;                                /* Device found */
                udelay(waitdelay);/* Required by AM335X in SPL */
                /* Abort transfer (force idle state) */
                omap_i2c_write_reg(i2c_base, ip_rev, I2C_CON_MST | I2C_CON_TRX,
                                   OMAP_I2C_CON_REG);   /* Reset */
                udelay(1000);
                omap_i2c_write_reg(i2c_base, ip_rev, I2C_CON_EN | I2C_CON_MST |
                                   I2C_CON_TRX | I2C_CON_STP,
                                   OMAP_I2C_CON_REG);   /* STP */
        }

pr_exit:
        flush_fifo(i2c_base, ip_rev);
        omap_i2c_write_reg(i2c_base, ip_rev, 0xFFFF, OMAP_I2C_STAT_REG);
        return res;
}

/*
 * i2c_read: Function now uses a single I2C read transaction with bulk transfer
 *           of the requested number of bytes (note that the 'i2c md' command
 *           limits this to 16 bytes anyway). If CONFIG_I2C_REPEATED_START is
 *           defined in the board config header, this transaction shall be with
 *           Repeated Start (Sr) between the address and data phases; otherwise
 *           Stop-Start (P-S) shall be used (some I2C chips do require a P-S).
 *           The address (reg offset) may be 0, 1 or 2 bytes long.
 *           Function now reads correctly from chips that return more than one
 *           byte of data per addressed register (like TI temperature sensors),
 *           or that do not need a register address at all (such as some clock
 *           distributors).
 */
static int __omap24_i2c_read(void __iomem *i2c_base, int ip_rev, int waitdelay,
                             uchar chip, uint addr, int alen, uchar *buffer,
                             int len)
{
        int i2c_error = 0;
        u16 status;

        if (alen < 0) {
                puts("I2C read: addr len < 0\n");
                return 1;
        }

        if (len < 0) {
                puts("I2C read: data len < 0\n");
                return 1;
        }

        if (buffer == NULL) {
                puts("I2C read: NULL pointer passed\n");
                return 1;
        }

        if (alen > 2) {
                printf("I2C read: addr len %d not supported\n", alen);
                return 1;
        }

        if (addr + len > (1 << 16)) {
                puts("I2C read: address out of range\n");
                return 1;
        }

#ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
        /*
         * EEPROM chips that implement "address overflow" are ones
         * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
         * address and the extra bits end up in the "chip address"
         * bit slots. This makes a 24WC08 (1Kbyte) chip look like
         * four 256 byte chips.
         *
         * Note that we consider the length of the address field to
         * still be one byte because the extra address bits are
         * hidden in the chip address.
         */
        if (alen > 0)
                chip |= ((addr >> (alen * 8)) &
                         CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
#endif

        /* Wait until bus not busy */
        if (wait_for_bb(i2c_base, ip_rev, waitdelay))
                return 1;

        /* Zero, one or two bytes reg address (offset) */
        omap_i2c_write_reg(i2c_base, ip_rev, alen, OMAP_I2C_CNT_REG);
        /* Set slave address */
        omap_i2c_write_reg(i2c_base, ip_rev, chip, OMAP_I2C_SA_REG);

        if (alen) {
                /* Must write reg offset first */
#ifdef CONFIG_I2C_REPEATED_START
                /* No stop bit, use Repeated Start (Sr) */
                omap_i2c_write_reg(i2c_base, ip_rev, I2C_CON_EN | I2C_CON_MST |
                                   I2C_CON_STT | I2C_CON_TRX, OMAP_I2C_CON_REG);
#else
                /* Stop - Start (P-S) */
                omap_i2c_write_reg(i2c_base, ip_rev, I2C_CON_EN | I2C_CON_MST |
                                   I2C_CON_STT | I2C_CON_STP | I2C_CON_TRX,
                                   OMAP_I2C_CON_REG);
#endif
                /* Send register offset */
                while (1) {
                        status = wait_for_event(i2c_base, ip_rev, waitdelay);
                        /* Try to identify bus that is not padconf'd for I2C */
                        if (status == I2C_STAT_XRDY) {
                                i2c_error = 2;
                                printf("i2c_read (addr phase): pads on bus probably not configured (status=0x%x)\n",
                                       status);
                                goto rd_exit;
                        }
                        if (status == 0 || (status & I2C_STAT_NACK)) {
                                i2c_error = 1;
                                printf("i2c_read: error waiting for addr ACK (status=0x%x)\n",
                                       status);
                                goto rd_exit;
                        }
                        if (alen) {
                                if (status & I2C_STAT_XRDY) {
                                        u8 addr_byte;
                                        alen--;
                                        addr_byte = (addr >> (8 * alen)) & 0xff;
                                        omap_i2c_write_reg(i2c_base, ip_rev,
                                                           addr_byte,
                                                           OMAP_I2C_DATA_REG);
                                        omap_i2c_write_reg(i2c_base, ip_rev,
                                                           I2C_STAT_XRDY,
                                                           OMAP_I2C_STAT_REG);
                                }
                        }
                        if (status & I2C_STAT_ARDY) {
                                omap_i2c_write_reg(i2c_base, ip_rev,
                                                   I2C_STAT_ARDY,
                                                   OMAP_I2C_STAT_REG);
                                break;
                        }
                }
        }

        /* Set slave address */
        omap_i2c_write_reg(i2c_base, ip_rev, chip, OMAP_I2C_SA_REG);
        /* Read len bytes from slave */
        omap_i2c_write_reg(i2c_base, ip_rev, len, OMAP_I2C_CNT_REG);
        /* Need stop bit here */
        omap_i2c_write_reg(i2c_base, ip_rev, I2C_CON_EN | I2C_CON_MST |
                           I2C_CON_STT | I2C_CON_STP, OMAP_I2C_CON_REG);

        /* Receive data */
        while (1) {
                status = wait_for_event(i2c_base, ip_rev, waitdelay);
                /*
                 * Try to identify bus that is not padconf'd for I2C. This
                 * state could be left over from previous transactions if
                 * the address phase is skipped due to alen=0.
                 */
                if (status == I2C_STAT_XRDY) {
                        i2c_error = 2;
                        printf("i2c_read (data phase): pads on bus probably not configured (status=0x%x)\n",
                               status);
                        goto rd_exit;
                }
                if (status == 0 || (status & I2C_STAT_NACK)) {
                        i2c_error = 1;
                        goto rd_exit;
                }
                if (status & I2C_STAT_RRDY) {
                        *buffer++ = omap_i2c_read_reg(i2c_base, ip_rev,
                                                      OMAP_I2C_DATA_REG);
                        omap_i2c_write_reg(i2c_base, ip_rev,
                                           I2C_STAT_RRDY, OMAP_I2C_STAT_REG);
                }
                if (status & I2C_STAT_ARDY) {
                        omap_i2c_write_reg(i2c_base, ip_rev,
                                           I2C_STAT_ARDY, OMAP_I2C_STAT_REG);
                        break;
                }
        }

rd_exit:
        flush_fifo(i2c_base, ip_rev);
        omap_i2c_write_reg(i2c_base, ip_rev, 0xFFFF, OMAP_I2C_STAT_REG);
        return i2c_error;
}

/* i2c_write: Address (reg offset) may be 0, 1 or 2 bytes long. */
static int __omap24_i2c_write(void __iomem *i2c_base, int ip_rev, int waitdelay,
                              uchar chip, uint addr, int alen, uchar *buffer,
                              int len)
{
        int i;
        u16 status;
        int i2c_error = 0;
        int timeout = I2C_TIMEOUT;

        if (alen < 0) {
                puts("I2C write: addr len < 0\n");
                return 1;
        }

        if (len < 0) {
                puts("I2C write: data len < 0\n");
                return 1;
        }

        if (buffer == NULL) {
                puts("I2C write: NULL pointer passed\n");
                return 1;
        }

        if (alen > 2) {
                printf("I2C write: addr len %d not supported\n", alen);
                return 1;
        }

        if (addr + len > (1 << 16)) {
                printf("I2C write: address 0x%x + 0x%x out of range\n",
                       addr, len);
                return 1;
        }

#ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
        /*
         * EEPROM chips that implement "address overflow" are ones
         * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
         * address and the extra bits end up in the "chip address"
         * bit slots. This makes a 24WC08 (1Kbyte) chip look like
         * four 256 byte chips.
         *
         * Note that we consider the length of the address field to
         * still be one byte because the extra address bits are
         * hidden in the chip address.
         */
        if (alen > 0)
                chip |= ((addr >> (alen * 8)) &
                         CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
#endif

        /* Wait until bus not busy */
        if (wait_for_bb(i2c_base, ip_rev, waitdelay))
                return 1;

        /* Start address phase - will write regoffset + len bytes data */
        omap_i2c_write_reg(i2c_base, ip_rev, alen + len, OMAP_I2C_CNT_REG);
        /* Set slave address */
        omap_i2c_write_reg(i2c_base, ip_rev, chip, OMAP_I2C_SA_REG);
        /* Stop bit needed here */
        omap_i2c_write_reg(i2c_base, ip_rev, I2C_CON_EN | I2C_CON_MST |
                           I2C_CON_STT | I2C_CON_TRX | I2C_CON_STP,
                           OMAP_I2C_CON_REG);

        while (alen) {
                /* Must write reg offset (one or two bytes) */
                status = wait_for_event(i2c_base, ip_rev, waitdelay);
                /* Try to identify bus that is not padconf'd for I2C */
                if (status == I2C_STAT_XRDY) {
                        i2c_error = 2;
                        printf("i2c_write: pads on bus probably not configured (status=0x%x)\n",
                               status);
                        goto wr_exit;
                }
                if (status == 0 || (status & I2C_STAT_NACK)) {
                        i2c_error = 1;
                        printf("i2c_write: error waiting for addr ACK (status=0x%x)\n",
                               status);
                        goto wr_exit;
                }
                if (status & I2C_STAT_XRDY) {
                        alen--;
                        omap_i2c_write_reg(i2c_base, ip_rev,
                                           (addr >> (8 * alen)) & 0xff,
                                           OMAP_I2C_DATA_REG);
                        omap_i2c_write_reg(i2c_base, ip_rev,
                                           I2C_STAT_XRDY, OMAP_I2C_STAT_REG);
                } else {
                        i2c_error = 1;
                        printf("i2c_write: bus not ready for addr Tx (status=0x%x)\n",
                               status);
                        goto wr_exit;
                }
        }

        /* Address phase is over, now write data */
        for (i = 0; i < len; i++) {
                status = wait_for_event(i2c_base, ip_rev, waitdelay);
                if (status == 0 || (status & I2C_STAT_NACK)) {
                        i2c_error = 1;
                        printf("i2c_write: error waiting for data ACK (status=0x%x)\n",
                               status);
                        goto wr_exit;
                }
                if (status & I2C_STAT_XRDY) {
                        omap_i2c_write_reg(i2c_base, ip_rev,
                                           buffer[i], OMAP_I2C_DATA_REG);
                        omap_i2c_write_reg(i2c_base, ip_rev,
                                           I2C_STAT_XRDY, OMAP_I2C_STAT_REG);
                } else {
                        i2c_error = 1;
                        printf("i2c_write: bus not ready for data Tx (i=%d)\n",
                               i);
                        goto wr_exit;
                }
        }

        /*
         * poll ARDY bit for making sure that last byte really has been
         * transferred on the bus.
         */
        do {
                status = wait_for_event(i2c_base, ip_rev, waitdelay);
        } while (!(status & I2C_STAT_ARDY) && timeout--);
        if (timeout <= 0)
                printf("i2c_write: timed out writig last byte!\n");

wr_exit:
        flush_fifo(i2c_base, ip_rev);
        omap_i2c_write_reg(i2c_base, ip_rev, 0xFFFF, OMAP_I2C_STAT_REG);
        return i2c_error;
}

#if !CONFIG_IS_ENABLED(DM_I2C)
/*
 * The legacy I2C functions. These need to get removed once
 * all users of this driver are converted to DM.
 */
static void __iomem *omap24_get_base(struct i2c_adapter *adap)
{
        switch (adap->hwadapnr) {
        case 0:
                return (void __iomem *)I2C_BASE1;
                break;
        case 1:
                return (void __iomem *)I2C_BASE2;
                break;
#if (CONFIG_SYS_I2C_BUS_MAX > 2)
        case 2:
                return (void __iomem *)I2C_BASE3;
                break;
#if (CONFIG_SYS_I2C_BUS_MAX > 3)
        case 3:
                return (void __iomem *)I2C_BASE4;
                break;
#if (CONFIG_SYS_I2C_BUS_MAX > 4)
        case 4:
                return (void __iomem *)I2C_BASE5;
                break;
#endif
#endif
#endif
        default:
                printf("wrong hwadapnr: %d\n", adap->hwadapnr);
                break;
        }

        return NULL;
}

static int omap24_get_ip_rev(void)
{
#ifdef CONFIG_OMAP34XX
        return OMAP_I2C_REV_V1;
#else
        return OMAP_I2C_REV_V2;
#endif
}

static int omap24_i2c_read(struct i2c_adapter *adap, uchar chip, uint addr,
                           int alen, uchar *buffer, int len)
{
        void __iomem *i2c_base = omap24_get_base(adap);
        int ip_rev = omap24_get_ip_rev();

        return __omap24_i2c_read(i2c_base, ip_rev, adap->waitdelay, chip, addr,
                                 alen, buffer, len);
}

static int omap24_i2c_write(struct i2c_adapter *adap, uchar chip, uint addr,
                            int alen, uchar *buffer, int len)
{
        void __iomem *i2c_base = omap24_get_base(adap);
        int ip_rev = omap24_get_ip_rev();

        return __omap24_i2c_write(i2c_base, ip_rev, adap->waitdelay, chip, addr,
                                  alen, buffer, len);
}

static uint omap24_i2c_setspeed(struct i2c_adapter *adap, uint speed)
{
        void __iomem *i2c_base = omap24_get_base(adap);
        int ip_rev = omap24_get_ip_rev();
        int ret;

        ret = __omap24_i2c_setspeed(i2c_base, ip_rev, speed, &adap->waitdelay);
        if (ret) {
                pr_err("%s: set i2c speed failed\n", __func__);
                return ret;
        }

        adap->speed = speed;

        return 0;
}

static void omap24_i2c_init(struct i2c_adapter *adap, int speed, int slaveadd)
{
        void __iomem *i2c_base = omap24_get_base(adap);
        int ip_rev = omap24_get_ip_rev();

        return __omap24_i2c_init(i2c_base, ip_rev, speed, slaveadd,
                                 &adap->waitdelay);
}

static int omap24_i2c_probe(struct i2c_adapter *adap, uchar chip)
{
        void __iomem *i2c_base = omap24_get_base(adap);
        int ip_rev = omap24_get_ip_rev();

        return __omap24_i2c_probe(i2c_base, ip_rev, adap->waitdelay, chip);
}

U_BOOT_I2C_ADAP_COMPLETE(omap24_0, omap24_i2c_init, omap24_i2c_probe,
                         omap24_i2c_read, omap24_i2c_write, omap24_i2c_setspeed,
                         CONFIG_SYS_I2C_SPEED,
                         CONFIG_SYS_I2C_SLAVE,
                         0)
U_BOOT_I2C_ADAP_COMPLETE(omap24_1, omap24_i2c_init, omap24_i2c_probe,
                         omap24_i2c_read, omap24_i2c_write, omap24_i2c_setspeed,
                         CONFIG_SYS_I2C_SPEED,
                         CONFIG_SYS_I2C_SLAVE,
                         1)

#if (CONFIG_SYS_I2C_BUS_MAX > 2)
U_BOOT_I2C_ADAP_COMPLETE(omap24_2, omap24_i2c_init, omap24_i2c_probe,
                         omap24_i2c_read, omap24_i2c_write, NULL,
                         CONFIG_SYS_I2C_SPEED,
                         CONFIG_SYS_I2C_SLAVE,
                         2)
#if (CONFIG_SYS_I2C_BUS_MAX > 3)
U_BOOT_I2C_ADAP_COMPLETE(omap24_3, omap24_i2c_init, omap24_i2c_probe,
                         omap24_i2c_read, omap24_i2c_write, NULL,
                         CONFIG_SYS_I2C_SPEED,
                         CONFIG_SYS_I2C_SLAVE,
                         3)
#if (CONFIG_SYS_I2C_BUS_MAX > 4)
U_BOOT_I2C_ADAP_COMPLETE(omap24_4, omap24_i2c_init, omap24_i2c_probe,
                         omap24_i2c_read, omap24_i2c_write, NULL,
                         CONFIG_SYS_I2C_SPEED,
                         CONFIG_SYS_I2C_SLAVE,
                         4)
#endif
#endif
#endif

#else /* CONFIG_DM_I2C */

static int omap_i2c_xfer(struct udevice *bus, struct i2c_msg *msg, int nmsgs)
{
        struct omap_i2c *priv = dev_get_priv(bus);
        int ret;

        debug("i2c_xfer: %d messages\n", nmsgs);
        for (; nmsgs > 0; nmsgs--, msg++) {
                debug("i2c_xfer: chip=0x%x, len=0x%x\n", msg->addr, msg->len);
                if (msg->flags & I2C_M_RD) {
                        ret = __omap24_i2c_read(priv->regs, priv->ip_rev,
                                                priv->waitdelay,
                                                msg->addr, 0, 0, msg->buf,
                                                msg->len);
                } else {
                        ret = __omap24_i2c_write(priv->regs, priv->ip_rev,
                                                 priv->waitdelay,
                                                 msg->addr, 0, 0, msg->buf,
                                                 msg->len);
                }
                if (ret) {
                        debug("i2c_write: error sending\n");
                        return -EREMOTEIO;
                }
        }

        return 0;
}

static int omap_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
{
        struct omap_i2c *priv = dev_get_priv(bus);

        priv->speed = speed;

        return __omap24_i2c_setspeed(priv->regs, priv->ip_rev, speed,
                                     &priv->waitdelay);
}

static int omap_i2c_probe_chip(struct udevice *bus, uint chip_addr,
                                     uint chip_flags)
{
        struct omap_i2c *priv = dev_get_priv(bus);

        return __omap24_i2c_probe(priv->regs, priv->ip_rev, priv->waitdelay,
                                  chip_addr);
}

static int omap_i2c_probe(struct udevice *bus)
{
        struct omap_i2c *priv = dev_get_priv(bus);
        struct omap_i2c_plat *plat = dev_get_plat(bus);

        priv->speed = plat->speed;
        priv->regs = map_physmem(plat->base, sizeof(void *),
                                 MAP_NOCACHE);
        priv->ip_rev = plat->ip_rev;

        __omap24_i2c_init(priv->regs, priv->ip_rev, priv->speed, 0,
                          &priv->waitdelay);

        return 0;
}

#if CONFIG_IS_ENABLED(OF_REAL)
static int omap_i2c_of_to_plat(struct udevice *bus)
{
        struct omap_i2c_plat *plat = dev_get_plat(bus);

        plat->base = dev_read_addr(bus);
        plat->speed = dev_read_u32_default(bus, "clock-frequency",
                                           I2C_SPEED_STANDARD_RATE);
        plat->ip_rev = dev_get_driver_data(bus);

        return 0;
}

static const struct udevice_id omap_i2c_ids[] = {
        { .compatible = "ti,omap3-i2c", .data = OMAP_I2C_REV_V1 },
        { .compatible = "ti,omap4-i2c", .data = OMAP_I2C_REV_V2 },
        { }
};
#endif

static const struct dm_i2c_ops omap_i2c_ops = {
        .xfer           = omap_i2c_xfer,
        .probe_chip     = omap_i2c_probe_chip,
        .set_bus_speed  = omap_i2c_set_bus_speed,
};

U_BOOT_DRIVER(i2c_omap) = {
        .name   = "i2c_omap",
        .id     = UCLASS_I2C,
#if CONFIG_IS_ENABLED(OF_REAL)
        .of_match = omap_i2c_ids,
        .of_to_plat = omap_i2c_of_to_plat,
        .plat_auto      = sizeof(struct omap_i2c_plat),
#endif
        .probe  = omap_i2c_probe,
        .priv_auto      = sizeof(struct omap_i2c),
        .ops    = &omap_i2c_ops,
#if !CONFIG_IS_ENABLED(OF_CONTROL)
        .flags  = DM_FLAG_PRE_RELOC,
#endif
};

#endif /* CONFIG_DM_I2C */