i2c: mvtwsi.c: Avoid NULL dereference

[people/ms/u-boot.git] / drivers / i2c / mvtwsi.c

/*
 * Driver for the TWSI (i2c) controller found on the Marvell
 * orion5x and kirkwood SoC families.
 *
 * Author: Albert Aribaud <albert.u.boot@aribaud.net>
 * Copyright (c) 2010 Albert Aribaud.
 *
 * SPDX-License-Identifier:     GPL-2.0+
 */

#include <common.h>
#include <i2c.h>
#include <linux/errno.h>
#include <asm/io.h>
#include <linux/compat.h>
#ifdef CONFIG_DM_I2C
#include <dm.h>
#endif

DECLARE_GLOBAL_DATA_PTR;

/*
 * Include a file that will provide CONFIG_I2C_MVTWSI_BASE*, and possibly other
 * settings
 */

#ifndef CONFIG_DM_I2C
#if defined(CONFIG_ORION5X)
#include <asm/arch/orion5x.h>
#elif (defined(CONFIG_KIRKWOOD) || defined(CONFIG_ARCH_MVEBU))
#include <asm/arch/soc.h>
#elif defined(CONFIG_ARCH_SUNXI)
#include <asm/arch/i2c.h>
#else
#error Driver mvtwsi not supported by SoC or board
#endif
#endif /* CONFIG_DM_I2C */

/*
 * On SUNXI, we get CONFIG_SYS_TCLK from this include, so we want to
 * always have it.
 */
#if defined(CONFIG_DM_I2C) && defined(CONFIG_ARCH_SUNXI)
#include <asm/arch/i2c.h>
#endif

/*
 * TWSI register structure
 */

#ifdef CONFIG_ARCH_SUNXI

struct  mvtwsi_registers {
        u32 slave_address;
        u32 xtnd_slave_addr;
        u32 data;
        u32 control;
        u32 status;
        u32 baudrate;
        u32 soft_reset;
};

#else

struct  mvtwsi_registers {
        u32 slave_address;
        u32 data;
        u32 control;
        union {
                u32 status;     /* When reading */
                u32 baudrate;   /* When writing */
        };
        u32 xtnd_slave_addr;
        u32 reserved[2];
        u32 soft_reset;
};

#endif

#ifdef CONFIG_DM_I2C
struct mvtwsi_i2c_dev {
        /* TWSI Register base for the device */
        struct mvtwsi_registers *base;
        /* Number of the device (determined from cell-index property) */
        int index;
        /* The I2C slave address for the device */
        u8 slaveadd;
        /* The configured I2C speed in Hz */
        uint speed;
        /* The current length of a clock period (depending on speed) */
        uint tick;
};
#endif /* CONFIG_DM_I2C */

/*
 * enum mvtwsi_ctrl_register_fields - Bit masks for flags in the control
 * register
 */
enum mvtwsi_ctrl_register_fields {
        /* Acknowledge bit */
        MVTWSI_CONTROL_ACK      = 0x00000004,
        /* Interrupt flag */
        MVTWSI_CONTROL_IFLG     = 0x00000008,
        /* Stop bit */
        MVTWSI_CONTROL_STOP     = 0x00000010,
        /* Start bit */
        MVTWSI_CONTROL_START    = 0x00000020,
        /* I2C enable */
        MVTWSI_CONTROL_TWSIEN   = 0x00000040,
        /* Interrupt enable */
        MVTWSI_CONTROL_INTEN    = 0x00000080,
};

/*
 * On sun6i and newer, IFLG is a write-clear bit, which is cleared by writing 1;
 * on other platforms, it is a normal r/w bit, which is cleared by writing 0.
 */

#ifdef CONFIG_SUNXI_GEN_SUN6I
#define MVTWSI_CONTROL_CLEAR_IFLG       0x00000008
#else
#define MVTWSI_CONTROL_CLEAR_IFLG       0x00000000
#endif

/*
 * enum mvstwsi_status_values - Possible values of I2C controller's status
 * register
 *
 * Only those statuses expected in normal master operation on
 * non-10-bit-address devices are specified.
 *
 * Every status that's unexpected during normal operation (bus errors,
 * arbitration losses, missing ACKs...) is passed back to the caller as an error
 * code.
 */
enum mvstwsi_status_values {
        /* START condition transmitted */
        MVTWSI_STATUS_START             = 0x08,
        /* Repeated START condition transmitted */
        MVTWSI_STATUS_REPEATED_START    = 0x10,
        /* Address + write bit transmitted, ACK received */
        MVTWSI_STATUS_ADDR_W_ACK        = 0x18,
        /* Data transmitted, ACK received */
        MVTWSI_STATUS_DATA_W_ACK        = 0x28,
        /* Address + read bit transmitted, ACK received */
        MVTWSI_STATUS_ADDR_R_ACK        = 0x40,
        /* Address + read bit transmitted, ACK not received */
        MVTWSI_STATUS_ADDR_R_NAK        = 0x48,
        /* Data received, ACK transmitted */
        MVTWSI_STATUS_DATA_R_ACK        = 0x50,
        /* Data received, ACK not transmitted */
        MVTWSI_STATUS_DATA_R_NAK        = 0x58,
        /* No relevant status */
        MVTWSI_STATUS_IDLE              = 0xF8,
};

/*
 * enum mvstwsi_ack_flags - Determine whether a read byte should be
 * acknowledged or not.
 */
enum mvtwsi_ack_flags {
        /* Send NAK after received byte */
        MVTWSI_READ_NAK = 0,
        /* Send ACK after received byte */
        MVTWSI_READ_ACK = 1,
};

/*
 * calc_tick() - Calculate the duration of a clock cycle from the I2C speed
 *
 * @speed:      The speed in Hz to calculate the clock cycle duration for.
 * @return The duration of a clock cycle in ns.
 */
inline uint calc_tick(uint speed)
{
        /* One tick = the duration of a period at the specified speed in ns (we
         * add 100 ns to be on the safe side) */
        return (1000000000u / speed) + 100;
}

#ifndef CONFIG_DM_I2C

/*
 * twsi_get_base() - Get controller register base for specified adapter
 *
 * @adap:       Adapter to get the register base for.
 * @return Register base for the specified adapter.
 */
static struct mvtwsi_registers *twsi_get_base(struct i2c_adapter *adap)
{
        switch (adap->hwadapnr) {
#ifdef CONFIG_I2C_MVTWSI_BASE0
        case 0:
                return (struct mvtwsi_registers *)CONFIG_I2C_MVTWSI_BASE0;
#endif
#ifdef CONFIG_I2C_MVTWSI_BASE1
        case 1:
                return (struct mvtwsi_registers *)CONFIG_I2C_MVTWSI_BASE1;
#endif
#ifdef CONFIG_I2C_MVTWSI_BASE2
        case 2:
                return (struct mvtwsi_registers *)CONFIG_I2C_MVTWSI_BASE2;
#endif
#ifdef CONFIG_I2C_MVTWSI_BASE3
        case 3:
                return (struct mvtwsi_registers *)CONFIG_I2C_MVTWSI_BASE3;
#endif
#ifdef CONFIG_I2C_MVTWSI_BASE4
        case 4:
                return (struct mvtwsi_registers *)CONFIG_I2C_MVTWSI_BASE4;
#endif
#ifdef CONFIG_I2C_MVTWSI_BASE5
        case 5:
                return (struct mvtwsi_registers *)CONFIG_I2C_MVTWSI_BASE5;
#endif
        default:
                printf("Missing mvtwsi controller %d base\n", adap->hwadapnr);
                break;
        }

        return NULL;
}
#endif

/*
 * enum mvtwsi_error_class - types of I2C errors
 */
enum mvtwsi_error_class {
        /* The controller returned a different status than expected */
        MVTWSI_ERROR_WRONG_STATUS       = 0x01,
        /* The controller timed out */
        MVTWSI_ERROR_TIMEOUT            = 0x02,
};

/*
 * mvtwsi_error() - Build I2C return code from error information
 *
 * For debugging purposes, this function packs some information of an occurred
 * error into a return code. These error codes are returned from I2C API
 * functions (i2c_{read,write}, dm_i2c_{read,write}, etc.).
 *
 * @ec:         The error class of the error (enum mvtwsi_error_class).
 * @lc:         The last value of the control register.
 * @ls:         The last value of the status register.
 * @es:         The expected value of the status register.
 * @return The generated error code.
 */
inline uint mvtwsi_error(uint ec, uint lc, uint ls, uint es)
{
        return ((ec << 24) & 0xFF000000)
               | ((lc << 16) & 0x00FF0000)
               | ((ls << 8) & 0x0000FF00)
               | (es & 0xFF);
}

/*
 * twsi_wait() - Wait for I2C bus interrupt flag and check status, or time out.
 *
 * @return Zero if status is as expected, or a non-zero code if either a time
 *         out occurred, or the status was not the expected one.
 */
static int twsi_wait(struct mvtwsi_registers *twsi, int expected_status,
                     uint tick)
{
        int control, status;
        int timeout = 1000;

        do {
                control = readl(&twsi->control);
                if (control & MVTWSI_CONTROL_IFLG) {
                        status = readl(&twsi->status);
                        if (status == expected_status)
                                return 0;
                        else
                                return mvtwsi_error(
                                        MVTWSI_ERROR_WRONG_STATUS,
                                        control, status, expected_status);
                }
                ndelay(tick); /* One clock cycle */
        } while (timeout--);
        status = readl(&twsi->status);
        return mvtwsi_error(MVTWSI_ERROR_TIMEOUT, control, status,
                            expected_status);
}

/*
 * twsi_start() - Assert a START condition on the bus.
 *
 * This function is used in both single I2C transactions and inside
 * back-to-back transactions (repeated starts).
 *
 * @twsi:               The MVTWSI register structure to use.
 * @expected_status:    The I2C bus status expected to be asserted after the
 *                      operation completion.
 * @tick:               The duration of a clock cycle at the current I2C speed.
 * @return Zero if status is as expected, or a non-zero code if either a time
 *         out occurred or the status was not the expected one.
 */
static int twsi_start(struct mvtwsi_registers *twsi, int expected_status,
                      uint tick)
{
        /* Assert START */
        writel(MVTWSI_CONTROL_TWSIEN | MVTWSI_CONTROL_START |
               MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control);
        /* Wait for controller to process START */
        return twsi_wait(twsi, expected_status, tick);
}

/*
 * twsi_send() - Send a byte on the I2C bus.
 *
 * The byte may be part of an address byte or data.
 *
 * @twsi:               The MVTWSI register structure to use.
 * @byte:               The byte to send.
 * @expected_status:    The I2C bus status expected to be asserted after the
 *                      operation completion.
 * @tick:               The duration of a clock cycle at the current I2C speed.
 * @return Zero if status is as expected, or a non-zero code if either a time
 *         out occurred or the status was not the expected one.
 */
static int twsi_send(struct mvtwsi_registers *twsi, u8 byte,
                     int expected_status, uint tick)
{
        /* Write byte to data register for sending */
        writel(byte, &twsi->data);
        /* Clear any pending interrupt -- that will cause sending */
        writel(MVTWSI_CONTROL_TWSIEN | MVTWSI_CONTROL_CLEAR_IFLG,
               &twsi->control);
        /* Wait for controller to receive byte, and check ACK */
        return twsi_wait(twsi, expected_status, tick);
}

/*
 * twsi_recv() - Receive a byte on the I2C bus.
 *
 * The static variable mvtwsi_control_flags controls whether we ack or nak.
 *
 * @twsi:               The MVTWSI register structure to use.
 * @byte:               The byte to send.
 * @ack_flag:           Flag that determines whether the received byte should
 *                      be acknowledged by the controller or not (sent ACK/NAK).
 * @tick:               The duration of a clock cycle at the current I2C speed.
 * @return Zero if status is as expected, or a non-zero code if either a time
 *         out occurred or the status was not the expected one.
 */
static int twsi_recv(struct mvtwsi_registers *twsi, u8 *byte, int ack_flag,
                     uint tick)
{
        int expected_status, status, control;

        /* Compute expected status based on passed ACK flag */
        expected_status = ack_flag ? MVTWSI_STATUS_DATA_R_ACK :
                          MVTWSI_STATUS_DATA_R_NAK;
        /* Acknowledge *previous state*, and launch receive */
        control = MVTWSI_CONTROL_TWSIEN;
        control |= ack_flag == MVTWSI_READ_ACK ? MVTWSI_CONTROL_ACK : 0;
        writel(control | MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control);
        /* Wait for controller to receive byte, and assert ACK or NAK */
        status = twsi_wait(twsi, expected_status, tick);
        /* If we did receive the expected byte, store it */
        if (status == 0)
                *byte = readl(&twsi->data);
        return status;
}

/*
 * twsi_stop() - Assert a STOP condition on the bus.
 *
 * This function is also used to force the bus back to idle state (SDA =
 * SCL = 1).
 *
 * @twsi:       The MVTWSI register structure to use.
 * @tick:       The duration of a clock cycle at the current I2C speed.
 * @return Zero if the operation succeeded, or a non-zero code if a time out
 *         occurred.
 */
static int twsi_stop(struct mvtwsi_registers *twsi, uint tick)
{
        int control, stop_status;
        int status = 0;
        int timeout = 1000;

        /* Assert STOP */
        control = MVTWSI_CONTROL_TWSIEN | MVTWSI_CONTROL_STOP;
        writel(control | MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control);
        /* Wait for IDLE; IFLG won't rise, so we can't use twsi_wait() */
        do {
                stop_status = readl(&twsi->status);
                if (stop_status == MVTWSI_STATUS_IDLE)
                        break;
                ndelay(tick); /* One clock cycle */
        } while (timeout--);
        control = readl(&twsi->control);
        if (stop_status != MVTWSI_STATUS_IDLE)
                status = mvtwsi_error(MVTWSI_ERROR_TIMEOUT,
                                      control, status, MVTWSI_STATUS_IDLE);
        return status;
}

/*
 * twsi_calc_freq() - Compute I2C frequency depending on m and n parameters.
 *
 * @n:          Parameter 'n' for the frequency calculation algorithm.
 * @m:          Parameter 'm' for the frequency calculation algorithm.
 * @return The I2C frequency corresponding to the passed m and n parameters.
 */
static uint twsi_calc_freq(const int n, const int m)
{
#ifdef CONFIG_ARCH_SUNXI
        return CONFIG_SYS_TCLK / (10 * (m + 1) * (1 << n));
#else
        return CONFIG_SYS_TCLK / (10 * (m + 1) * (2 << n));
#endif
}

/*
 * twsi_reset() - Reset the I2C controller.
 *
 * Resetting the controller also resets the baud rate and slave address, hence
 * they must be re-established after the reset.
 *
 * @twsi:       The MVTWSI register structure to use.
 */
static void twsi_reset(struct mvtwsi_registers *twsi)
{
        /* Reset controller */
        writel(0, &twsi->soft_reset);
        /* Wait 2 ms -- this is what the Marvell LSP does */
        udelay(20000);
}

/*
 * __twsi_i2c_set_bus_speed() - Set the speed of the I2C controller.
 *
 * This function sets baud rate to the highest possible value that does not
 * exceed the requested rate.
 *
 * @twsi:               The MVTWSI register structure to use.
 * @requested_speed:    The desired frequency the controller should run at
 *                      in Hz.
 * @return The actual frequency the controller was configured to.
 */
static uint __twsi_i2c_set_bus_speed(struct mvtwsi_registers *twsi,
                                     uint requested_speed)
{
        uint tmp_speed, highest_speed, n, m;
        uint baud = 0x44; /* Baud rate after controller reset */

        highest_speed = 0;
        /* Successively try m, n combinations, and use the combination
         * resulting in the largest speed that's not above the requested
         * speed */
        for (n = 0; n < 8; n++) {
                for (m = 0; m < 16; m++) {
                        tmp_speed = twsi_calc_freq(n, m);
                        if ((tmp_speed <= requested_speed) &&
                            (tmp_speed > highest_speed)) {
                                highest_speed = tmp_speed;
                                baud = (m << 3) | n;
                        }
                }
        }
        writel(baud, &twsi->baudrate);

        /* Wait for controller for one tick */
#ifdef CONFIG_DM_I2C
        ndelay(calc_tick(highest_speed));
#else
        ndelay(10000);
#endif
        return highest_speed;
}

/*
 * __twsi_i2c_init() - Initialize the I2C controller.
 *
 * @twsi:               The MVTWSI register structure to use.
 * @speed:              The initial frequency the controller should run at
 *                      in Hz.
 * @slaveadd:           The I2C address to be set for the I2C master.
 * @actual_speed:       A output parameter that receives the actual frequency
 *                      in Hz the controller was set to by the function.
 * @return Zero if the operation succeeded, or a non-zero code if a time out
 *         occurred.
 */
static void __twsi_i2c_init(struct mvtwsi_registers *twsi, int speed,
                            int slaveadd, uint *actual_speed)
{
        /* Reset controller */
        twsi_reset(twsi);
        /* Set speed */
        if (actual_speed)
                *actual_speed = __twsi_i2c_set_bus_speed(twsi, speed);
        /* Set slave address; even though we don't use it */
        writel(slaveadd, &twsi->slave_address);
        writel(0, &twsi->xtnd_slave_addr);
        /* Assert STOP, but don't care for the result */
#ifdef CONFIG_DM_I2C
        (void) twsi_stop(twsi, calc_tick(*actual_speed));
#else
        (void) twsi_stop(twsi, 10000);
#endif
}

/*
 * i2c_begin() - Start a I2C transaction.
 *
 * Begin a I2C transaction with a given expected start status and chip address.
 * A START is asserted, and the address byte is sent to the I2C controller. The
 * expected address status will be derived from the direction bit (bit 0) of
 * the address byte.
 *
 * @twsi:                       The MVTWSI register structure to use.
 * @expected_start_status:      The I2C status the controller is expected to
 *                              assert after the address byte was sent.
 * @addr:                       The address byte to be sent.
 * @tick:                       The duration of a clock cycle at the current
 *                              I2C speed.
 * @return Zero if the operation succeeded, or a non-zero code if a time out or
 *         unexpected I2C status occurred.
 */
static int i2c_begin(struct mvtwsi_registers *twsi, int expected_start_status,
                     u8 addr, uint tick)
{
        int status, expected_addr_status;

        /* Compute the expected address status from the direction bit in
         * the address byte */
        if (addr & 1) /* Reading */
                expected_addr_status = MVTWSI_STATUS_ADDR_R_ACK;
        else /* Writing */
                expected_addr_status = MVTWSI_STATUS_ADDR_W_ACK;
        /* Assert START */
        status = twsi_start(twsi, expected_start_status, tick);
        /* Send out the address if the start went well */
        if (status == 0)
                status = twsi_send(twsi, addr, expected_addr_status, tick);
        /* Return 0, or the status of the first failure */
        return status;
}

/*
 * __twsi_i2c_probe_chip() - Probe the given I2C chip address.
 *
 * This function begins a I2C read transaction, does a dummy read and NAKs; if
 * the procedure succeeds, the chip is considered to be present.
 *
 * @twsi:       The MVTWSI register structure to use.
 * @chip:       The chip address to probe.
 * @tick:       The duration of a clock cycle at the current I2C speed.
 * @return Zero if the operation succeeded, or a non-zero code if a time out or
 *         unexpected I2C status occurred.
 */
static int __twsi_i2c_probe_chip(struct mvtwsi_registers *twsi, uchar chip,
                                 uint tick)
{
        u8 dummy_byte;
        int status;

        /* Begin i2c read */
        status = i2c_begin(twsi, MVTWSI_STATUS_START, (chip << 1) | 1, tick);
        /* Dummy read was accepted: receive byte, but NAK it. */
        if (status == 0)
                status = twsi_recv(twsi, &dummy_byte, MVTWSI_READ_NAK, tick);
        /* Stop transaction */
        twsi_stop(twsi, tick);
        /* Return 0, or the status of the first failure */
        return status;
}

/*
 * __twsi_i2c_read() - Read data from a I2C chip.
 *
 * This function begins a I2C write transaction, and transmits the address
 * bytes; then begins a I2C read transaction, and receives the data bytes.
 *
 * NOTE: Some devices want a stop right before the second start, while some
 * will choke if it is there. Since deciding this is not yet supported in
 * higher level APIs, we need to make a decision here, and for the moment that
 * will be a repeated start without a preceding stop.
 *
 * @twsi:       The MVTWSI register structure to use.
 * @chip:       The chip address to read from.
 * @addr:       The address bytes to send.
 * @alen:       The length of the address bytes in bytes.
 * @data:       The buffer to receive the data read from the chip (has to have
 *              a size of at least 'length' bytes).
 * @length:     The amount of data to be read from the chip in bytes.
 * @tick:       The duration of a clock cycle at the current I2C speed.
 * @return Zero if the operation succeeded, or a non-zero code if a time out or
 *         unexpected I2C status occurred.
 */
static int __twsi_i2c_read(struct mvtwsi_registers *twsi, uchar chip,
                           u8 *addr, int alen, uchar *data, int length,
                           uint tick)
{
        int status = 0;
        int stop_status;
        int expected_start = MVTWSI_STATUS_START;

        if (alen > 0) {
                /* Begin i2c write to send the address bytes */
                status = i2c_begin(twsi, expected_start, (chip << 1), tick);
                /* Send address bytes */
                while ((status == 0) && alen--)
                        status = twsi_send(twsi, addr[alen],
                                           MVTWSI_STATUS_DATA_W_ACK, tick);
                /* Send repeated STARTs after the initial START */
                expected_start = MVTWSI_STATUS_REPEATED_START;
        }
        /* Begin i2c read to receive data bytes */
        if (status == 0)
                status = i2c_begin(twsi, expected_start, (chip << 1) | 1, tick);
        /* Receive actual data bytes; set NAK if we if we have nothing more to
         * read */
        while ((status == 0) && length--)
                status = twsi_recv(twsi, data++,
                                   length > 0 ?
                                   MVTWSI_READ_ACK : MVTWSI_READ_NAK, tick);
        /* Stop transaction */
        stop_status = twsi_stop(twsi, tick);
        /* Return 0, or the status of the first failure */
        return status != 0 ? status : stop_status;
}

/*
 * __twsi_i2c_write() - Send data to a I2C chip.
 *
 * This function begins a I2C write transaction, and transmits the address
 * bytes; then begins a new I2C write transaction, and sends the data bytes.
 *
 * @twsi:       The MVTWSI register structure to use.
 * @chip:       The chip address to read from.
 * @addr:       The address bytes to send.
 * @alen:       The length of the address bytes in bytes.
 * @data:       The buffer containing the data to be sent to the chip.
 * @length:     The length of data to be sent to the chip in bytes.
 * @tick:       The duration of a clock cycle at the current I2C speed.
 * @return Zero if the operation succeeded, or a non-zero code if a time out or
 *         unexpected I2C status occurred.
 */
static int __twsi_i2c_write(struct mvtwsi_registers *twsi, uchar chip,
                            u8 *addr, int alen, uchar *data, int length,
                            uint tick)
{
        int status, stop_status;

        /* Begin i2c write to send first the address bytes, then the
         * data bytes */
        status = i2c_begin(twsi, MVTWSI_STATUS_START, (chip << 1), tick);
        /* Send address bytes */
        while ((status == 0) && (alen-- > 0))
                status = twsi_send(twsi, addr[alen], MVTWSI_STATUS_DATA_W_ACK,
                                   tick);
        /* Send data bytes */
        while ((status == 0) && (length-- > 0))
                status = twsi_send(twsi, *(data++), MVTWSI_STATUS_DATA_W_ACK,
                                   tick);
        /* Stop transaction */
        stop_status = twsi_stop(twsi, tick);
        /* Return 0, or the status of the first failure */
        return status != 0 ? status : stop_status;
}

#ifndef CONFIG_DM_I2C
static void twsi_i2c_init(struct i2c_adapter *adap, int speed,
                          int slaveadd)
{
        struct mvtwsi_registers *twsi = twsi_get_base(adap);
        __twsi_i2c_init(twsi, speed, slaveadd, NULL);
}

static uint twsi_i2c_set_bus_speed(struct i2c_adapter *adap,
                                   uint requested_speed)
{
        struct mvtwsi_registers *twsi = twsi_get_base(adap);
        __twsi_i2c_set_bus_speed(twsi, requested_speed);
        return 0;
}

static int twsi_i2c_probe(struct i2c_adapter *adap, uchar chip)
{
        struct mvtwsi_registers *twsi = twsi_get_base(adap);
        return __twsi_i2c_probe_chip(twsi, chip, 10000);
}

static int twsi_i2c_read(struct i2c_adapter *adap, uchar chip, uint addr,
                         int alen, uchar *data, int length)
{
        struct mvtwsi_registers *twsi = twsi_get_base(adap);
        u8 addr_bytes[4];

        addr_bytes[0] = (addr >> 0) & 0xFF;
        addr_bytes[1] = (addr >> 8) & 0xFF;
        addr_bytes[2] = (addr >> 16) & 0xFF;
        addr_bytes[3] = (addr >> 24) & 0xFF;

        return __twsi_i2c_read(twsi, chip, addr_bytes, alen, data, length,
                               10000);
}

static int twsi_i2c_write(struct i2c_adapter *adap, uchar chip, uint addr,
                          int alen, uchar *data, int length)
{
        struct mvtwsi_registers *twsi = twsi_get_base(adap);
        u8 addr_bytes[4];

        addr_bytes[0] = (addr >> 0) & 0xFF;
        addr_bytes[1] = (addr >> 8) & 0xFF;
        addr_bytes[2] = (addr >> 16) & 0xFF;
        addr_bytes[3] = (addr >> 24) & 0xFF;

        return __twsi_i2c_write(twsi, chip, addr_bytes, alen, data, length,
                                10000);
}

#ifdef CONFIG_I2C_MVTWSI_BASE0
U_BOOT_I2C_ADAP_COMPLETE(twsi0, twsi_i2c_init, twsi_i2c_probe,
                         twsi_i2c_read, twsi_i2c_write,
                         twsi_i2c_set_bus_speed,
                         CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE, 0)
#endif
#ifdef CONFIG_I2C_MVTWSI_BASE1
U_BOOT_I2C_ADAP_COMPLETE(twsi1, twsi_i2c_init, twsi_i2c_probe,
                         twsi_i2c_read, twsi_i2c_write,
                         twsi_i2c_set_bus_speed,
                         CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE, 1)

#endif
#ifdef CONFIG_I2C_MVTWSI_BASE2
U_BOOT_I2C_ADAP_COMPLETE(twsi2, twsi_i2c_init, twsi_i2c_probe,
                         twsi_i2c_read, twsi_i2c_write,
                         twsi_i2c_set_bus_speed,
                         CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE, 2)

#endif
#ifdef CONFIG_I2C_MVTWSI_BASE3
U_BOOT_I2C_ADAP_COMPLETE(twsi3, twsi_i2c_init, twsi_i2c_probe,
                         twsi_i2c_read, twsi_i2c_write,
                         twsi_i2c_set_bus_speed,
                         CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE, 3)

#endif
#ifdef CONFIG_I2C_MVTWSI_BASE4
U_BOOT_I2C_ADAP_COMPLETE(twsi4, twsi_i2c_init, twsi_i2c_probe,
                         twsi_i2c_read, twsi_i2c_write,
                         twsi_i2c_set_bus_speed,
                         CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE, 4)

#endif
#ifdef CONFIG_I2C_MVTWSI_BASE5
U_BOOT_I2C_ADAP_COMPLETE(twsi5, twsi_i2c_init, twsi_i2c_probe,
                         twsi_i2c_read, twsi_i2c_write,
                         twsi_i2c_set_bus_speed,
                         CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE, 5)

#endif
#else /* CONFIG_DM_I2C */

static int mvtwsi_i2c_probe_chip(struct udevice *bus, u32 chip_addr,
                                 u32 chip_flags)
{
        struct mvtwsi_i2c_dev *dev = dev_get_priv(bus);
        return __twsi_i2c_probe_chip(dev->base, chip_addr, dev->tick);
}

static int mvtwsi_i2c_set_bus_speed(struct udevice *bus, uint speed)
{
        struct mvtwsi_i2c_dev *dev = dev_get_priv(bus);

        dev->speed = __twsi_i2c_set_bus_speed(dev->base, speed);
        dev->tick = calc_tick(dev->speed);

        return 0;
}

static int mvtwsi_i2c_ofdata_to_platdata(struct udevice *bus)
{
        struct mvtwsi_i2c_dev *dev = dev_get_priv(bus);

        dev->base = devfdt_get_addr_ptr(bus);

        if (!dev->base)
                return -ENOMEM;

        dev->index = fdtdec_get_int(gd->fdt_blob, dev_of_offset(bus),
                                    "cell-index", -1);
        dev->slaveadd = fdtdec_get_int(gd->fdt_blob, dev_of_offset(bus),
                                       "u-boot,i2c-slave-addr", 0x0);
        dev->speed = fdtdec_get_int(gd->fdt_blob, dev_of_offset(bus),
                                    "clock-frequency", 100000);
        return 0;
}

static int mvtwsi_i2c_probe(struct udevice *bus)
{
        struct mvtwsi_i2c_dev *dev = dev_get_priv(bus);
        uint actual_speed;

        __twsi_i2c_init(dev->base, dev->speed, dev->slaveadd, &actual_speed);
        dev->speed = actual_speed;
        dev->tick = calc_tick(dev->speed);
        return 0;
}

static int mvtwsi_i2c_xfer(struct udevice *bus, struct i2c_msg *msg, int nmsgs)
{
        struct mvtwsi_i2c_dev *dev = dev_get_priv(bus);
        struct i2c_msg *dmsg, *omsg, dummy;

        memset(&dummy, 0, sizeof(struct i2c_msg));

        /* We expect either two messages (one with an offset and one with the
         * actual data) or one message (just data or offset/data combined) */
        if (nmsgs > 2 || nmsgs == 0) {
                debug("%s: Only one or two messages are supported.", __func__);
                return -1;
        }

        omsg = nmsgs == 1 ? &dummy : msg;
        dmsg = nmsgs == 1 ? msg : msg + 1;

        if (dmsg->flags & I2C_M_RD)
                return __twsi_i2c_read(dev->base, dmsg->addr, omsg->buf,
                                       omsg->len, dmsg->buf, dmsg->len,
                                       dev->tick);
        else
                return __twsi_i2c_write(dev->base, dmsg->addr, omsg->buf,
                                        omsg->len, dmsg->buf, dmsg->len,
                                        dev->tick);
}

static const struct dm_i2c_ops mvtwsi_i2c_ops = {
        .xfer           = mvtwsi_i2c_xfer,
        .probe_chip     = mvtwsi_i2c_probe_chip,
        .set_bus_speed  = mvtwsi_i2c_set_bus_speed,
};

static const struct udevice_id mvtwsi_i2c_ids[] = {
        { .compatible = "marvell,mv64xxx-i2c", },
        { .compatible = "marvell,mv78230-i2c", },
        { .compatible = "allwinner,sun6i-a31-i2c", },
        { /* sentinel */ }
};

U_BOOT_DRIVER(i2c_mvtwsi) = {
        .name = "i2c_mvtwsi",
        .id = UCLASS_I2C,
        .of_match = mvtwsi_i2c_ids,
        .probe = mvtwsi_i2c_probe,
        .ofdata_to_platdata = mvtwsi_i2c_ofdata_to_platdata,
        .priv_auto_alloc_size = sizeof(struct mvtwsi_i2c_dev),
        .ops = &mvtwsi_i2c_ops,
};
#endif /* CONFIG_DM_I2C */