RIOT/cpu/kinetis_common/i2c.c

/*
 * Copyright (C) 2014 Freie Universität Berlin
 * Copyright (C) 2014 PHYTEC Messtechnik GmbH
 *
 * This file is subject to the terms and conditions of the GNU Lesser
 * General Public License v2.1. See the file LICENSE in the top level
 * directory for more details.
 */

/**
 * @ingroup     cpu_kinetis_common_i2c
 *
 * @note        This driver only implements the 7-bit addressing master mode.
 *
 * @{
 *
 * @file
 * @brief       Low-level I2C driver implementation
 *
 * @author      Johann Fischer <j.fischer@phytec.de>
 *
 * @}
 */

#include <stdint.h>

#include "cpu.h"
#include "irq.h"
#include "mutex.h"
#include "periph_conf.h"
#include "periph/i2c.h"

#define ENABLE_DEBUG    (0)
#include "debug.h"

/* guard file in case no I2C device is defined */
#if I2C_NUMOF

/**
 * @brief Array holding one pre-initialized mutex for each I2C device
 */
static mutex_t locks[] =  {
#if I2C_0_EN
    [I2C_0] = MUTEX_INIT,
#endif
#if I2C_1_EN
    [I2C_1] = MUTEX_INIT,
#endif
#if I2C_2_EN
    [I2C_2] = MUTEX_INIT
#endif
#if I2C_3_EN
    [I2C_3] = MUTEX_INIT
#endif
};

int i2c_acquire(i2c_t dev)
{
    if (dev >= I2C_NUMOF) {
        return -1;
    }
    mutex_lock(&locks[dev]);
    return 0;
}

int i2c_release(i2c_t dev)
{
    if (dev >= I2C_NUMOF) {
        return -1;
    }
    mutex_unlock(&locks[dev]);
    return 0;
}

int i2c_init_master(i2c_t dev, i2c_speed_t speed)
{
    I2C_Type *i2c;
    PORT_Type *i2c_port;
    int pin_scl = 0;
    int pin_sda = 0;

    /* TODO: read speed configuration */
    switch (speed) {
        case I2C_SPEED_NORMAL:
            break;

        case I2C_SPEED_FAST:
            break;

        default:
            return -2;
    }

    /* read static device configuration */
    switch (dev) {
#if I2C_0_EN

        case I2C_0:
            i2c = I2C_0_DEV;
            i2c_port = I2C_0_PORT;
            pin_scl = I2C_0_SCL_PIN;
            pin_sda = I2C_0_SDA_PIN;
            I2C_0_CLKEN();
            I2C_0_PORT_CLKEN();
            break;
#endif

        default:
            return -1;
    }

    /* configure pins, alternate output */
    i2c_port->PCR[pin_scl] = I2C_0_PORT_CFG;
    i2c_port->PCR[pin_sda] = I2C_0_PORT_CFG;

    /* 
    * TODO: Add baud rate selection function
    * See the Chapter "I2C divider and hold values":
    *     Kinetis K60 Reference Manual, section 51.4.1.10, Table 51-41. 
    *     Kinetis MKW2x  Reference Manual, section 52.4.1.10, Table 52-41. 
    *
    * baud rate = I2C_module_clock / (mul × ICR)
    *
    * The assignment below will set baud rate to I2C_module_clock / (240 x 2).
    */
    i2c->F = I2C_F_MULT(1) | I2C_F_ICR(0x1f);

    /* enable i2c-module and interrupt */
    i2c->C1 = I2C_C1_IICEN_MASK | I2C_C1_IICIE_MASK | I2C_C1_TXAK_MASK;
    i2c->C2 = 0;

    return 0;
}

int i2c_init_slave(i2c_t dev, uint8_t address)
{
    /* TODO: implement slave mode */
    return -1;
}

static inline int _i2c_start(I2C_Type *dev, uint8_t address, uint8_t rw_flag)
{
    /* bus free ? */
    if (dev->S & I2C_S_BUSY_MASK) {
        return -1;
    }

    dev->S = I2C_S_IICIF_MASK;

    dev->C1 = I2C_C1_IICEN_MASK | I2C_C1_MST_MASK | I2C_C1_TX_MASK;
    dev->D = address << 1 | (rw_flag & 1);

    /* wait for bus-busy to be set */
    while (!(dev->S & I2C_S_BUSY_MASK));

    /* wait for address transfer to complete */
    while (!(dev->S & I2C_S_IICIF_MASK));

    dev->S = I2C_S_IICIF_MASK;

    /* check for receive acknowledge */
    if (dev->S & I2C_S_RXAK_MASK) {
        return -1;
    }

    return 0;
}

static inline int _i2c_restart(I2C_Type *dev, uint8_t address, uint8_t rw_flag)
{
    /* put master in rx mode and repeat start */
    dev->C1 |= I2C_C1_RSTA_MASK;
    dev->D = address << 1 | (rw_flag & 1);

    /* wait for address transfer to complete */
    while (!(dev->S & I2C_S_IICIF_MASK));

    dev->S = I2C_S_IICIF_MASK;

    /* check for receive acknowledge */
    if (dev->S & I2C_S_RXAK_MASK) {
        return -1;
    }

    return 0;
}

static inline int _i2c_receive(I2C_Type *dev, uint8_t *data, int length)
{
    int n = 0;

    /* set receive mode */
    dev->C1 = I2C_C1_IICEN_MASK | I2C_C1_MST_MASK;

    if (length == 1) {
        /* no ack signal */
        dev->C1 |= I2C_C1_TXAK_MASK;
    }

    /* dummy read */
    dev->D;

    while (length > 0) {
        while (!(dev->S & I2C_S_IICIF_MASK));

        dev->S = I2C_S_IICIF_MASK;

        if (length == 2) {
            /* no ack signal is sent on the following receiving byte */
            dev->C1 |= I2C_C1_TXAK_MASK;
        }

        if (length == 1) {
            /* generate stop */
            dev->C1 &= ~I2C_C1_MST_MASK;
        }

        data[n] = (char)dev->D;
        length--;
        n++;
    }

    return n;
}

static inline int _i2c_transmit(I2C_Type *dev, uint8_t *data, int length)
{
    int n = 0;

    while (length > 0) {
        dev->D = data[n];

        while (!(dev->S & I2C_S_IICIF_MASK));

        dev->S = I2C_S_IICIF_MASK;

        if (dev->S & I2C_S_RXAK_MASK) {
            return n;
        }

        n++;
        length--;
    }

    return n;
}

static inline void _i2c_stop(I2C_Type *dev)
{
    /* put bus in idle state */
    dev->C1 = I2C_C1_IICEN_MASK;

    /* wait for bus idle */
    while (dev->S & I2C_S_BUSY_MASK);
}


int i2c_read_byte(i2c_t dev, uint8_t address, char *data)
{
    return i2c_read_bytes(dev, address, data, 1);
}

int i2c_read_bytes(i2c_t dev, uint8_t address, char *data, int length)
{
    I2C_Type *i2c;
    int n = 0;

    switch (dev) {
#if I2C_0_EN

        case I2C_0:
            i2c = I2C_0_DEV;
            break;
#endif

        default:
            return -1;
    }

    if (_i2c_start(i2c, address, I2C_FLAG_READ)) {
        _i2c_stop(i2c);
        return -1;
    }

    n = _i2c_receive(i2c, (uint8_t *)data, length);
    _i2c_stop(i2c);

    return n;
}

int i2c_write_byte(i2c_t dev, uint8_t address, char data)
{
    return i2c_write_bytes(dev, address, &data, 1);
}

int i2c_write_bytes(i2c_t dev, uint8_t address, char *data, int length)
{
    I2C_Type *i2c;
    int n = 0;

    switch (dev) {
#if I2C_0_EN

        case I2C_0:
            i2c = I2C_0_DEV;
            break;
#endif

        default:
            return -1;
    }

    if (_i2c_start(i2c, address, I2C_FLAG_WRITE)) {
        _i2c_stop(i2c);
        return -1;
    }

    n = _i2c_transmit(i2c, (uint8_t *)data, length);
    _i2c_stop(i2c);

    return n;
}

int i2c_read_reg(i2c_t dev, uint8_t address, uint8_t reg, char *data)
{
    return i2c_read_regs(dev, address, reg, data, 1);

}

int i2c_read_regs(i2c_t dev, uint8_t address, uint8_t reg, char *data, int length)
{
    I2C_Type *i2c;
    int n = 0;

    switch (dev) {
#if I2C_0_EN

        case I2C_0:
            i2c = I2C_0_DEV;
            break;
#endif

        default:
            return -1;
    }

    if (_i2c_start(i2c, address, I2C_FLAG_WRITE)) {
        _i2c_stop(i2c);
        return -1;
    }

    /* send reg */
    n = _i2c_transmit(i2c, &reg, 1);

    if (!n) {
        _i2c_stop(i2c);
        return n;
    }

    if (_i2c_restart(i2c, address, I2C_FLAG_READ)) {
        _i2c_stop(i2c);
        return -1;
    }

    n = _i2c_receive(i2c, (uint8_t *)data, length);
    _i2c_stop(i2c);

    return n;
}


int i2c_write_reg(i2c_t dev, uint8_t address, uint8_t reg, char data)
{
    return i2c_write_regs(dev, address, reg, &data, 1);
}

int i2c_write_regs(i2c_t dev, uint8_t address, uint8_t reg, char *data, int length)
{
    I2C_Type *i2c;
    int n = 0;

    switch (dev) {
#if I2C_0_EN

        case I2C_0:
            i2c = I2C_0_DEV;
            break;
#endif

        default:
            return -1;
    }

    if (_i2c_start(i2c, address, I2C_FLAG_WRITE)) {
        _i2c_stop(i2c);
        return -1;
    }

    n = _i2c_transmit(i2c, &reg, 1);

    if (!n) {
        _i2c_stop(i2c);
        return n;
    }

    n = _i2c_transmit(i2c, (uint8_t *)data, length);
    _i2c_stop(i2c);

    return n;
}

void i2c_poweron(i2c_t dev)
{
    switch (dev) {
#if I2C_0_EN

        case I2C_0:
            I2C_0_CLKEN();
            break;
#endif
    }
}

void i2c_poweroff(i2c_t dev)
{
    switch (dev) {
#if I2C_0_EN

        case I2C_0:
            I2C_0_CLKDIS();
            break;
#endif
    }
}

#endif /* I2C_NUMOF */