tinySA/os/hal/platforms/AVR/i2c_lld.c

/*
    ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
                 2011,2012,2013 Giovanni Di Sirio.

    This file is part of ChibiOS/RT.

    ChibiOS/RT is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    ChibiOS/RT is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 * @file    AVR/i2c_lld.c
 * @brief   AVR I2C subsystem low level driver source.
 *
 * @addtogroup I2C
 * @{
 */

#include "ch.h"
#include "hal.h"

#if HAL_USE_I2C || defined(__DOXYGEN__)

/*===========================================================================*/
/* Driver local definitions.                                                 */
/*===========================================================================*/

/*===========================================================================*/
/* Driver exported variables.                                                */
/*===========================================================================*/

/** @brief I2C driver identifier.*/
#if USE_AVR_I2C || defined(__DOXYGEN__)
I2CDriver I2CD;
#endif

/*===========================================================================*/
/* Driver local variables.                                                   */
/*===========================================================================*/

/*===========================================================================*/
/* Driver local functions.                                                   */
/*===========================================================================*/

/**
 * @brief   Wakes up the waiting thread.
 *
 * @param[in] i2cp      pointer to the @p I2CDriver object
 * @param[in] msg       wakeup message
 *
 * @notapi
 */
#define wakeup_isr(i2cp, msg) {                                             \
  chSysLockFromIsr();                                                       \
  if ((i2cp)->thread != NULL) {                                             \
    Thread *tp = (i2cp)->thread;                                            \
    (i2cp)->thread = NULL;                                                  \
    tp->p_u.rdymsg = (msg);                                                 \
    chSchReadyI(tp);                                                        \
  }                                                                         \
  chSysUnlockFromIsr();                                                     \
}

/*===========================================================================*/
/* Driver interrupt handlers.                                                */
/*===========================================================================*/

#if USE_AVR_I2C || defined(__DOXYGEN__)
/**
 * @brief   I2C event interrupt handler.
 *
 * @notapi
 */
CH_IRQ_HANDLER(TWI_vect) {
  CH_IRQ_PROLOGUE();

  I2CDriver *i2cp = &I2CD;

  switch (TWSR & 0xF8) {
  case TWI_START:
  case TWI_REPEAT_START:
    TWDR = (i2cp->addr << 1);
    if ((i2cp->txbuf == NULL) || (i2cp->txbytes == 0) || (i2cp->txidx == i2cp->txbytes)) {
      TWDR |= 0x01;
    }
    TWCR = ((1 << TWINT) | (1 << TWEN) | (1 << TWIE));
    break;
  case TWI_MASTER_TX_ADDR_ACK:
  case TWI_MASTER_TX_DATA_ACK:
    if (i2cp->txidx < i2cp->txbytes) {
      TWDR = i2cp->txbuf[i2cp->txidx++];
      TWCR = ((1 << TWINT) | (1 << TWEN) | (1 << TWIE));
    } else {
      if (i2cp->rxbuf && i2cp->rxbytes) {
        TWCR = ((1 << TWSTA) | (1 << TWINT) | (1 << TWEN) | (1 << TWIE));
      } else {
        TWCR = ((1 << TWSTO) | (1 << TWINT) | (1 << TWEN));
        wakeup_isr(i2cp, RDY_OK);
      }
    }
    break;
  case TWI_MASTER_RX_ADDR_ACK:
    if (i2cp->rxidx == (i2cp->rxbytes - 1)) {
      TWCR = ((1 << TWINT) | (1 << TWEN) | (1 << TWIE));
    } else {
      TWCR = ((1 << TWEA) | (1 << TWINT) | (1 << TWEN) | (1 << TWIE));
    }
    break;
  case TWI_MASTER_RX_DATA_ACK:
    i2cp->rxbuf[i2cp->rxidx++] = TWDR;
    if (i2cp->rxidx == (i2cp->rxbytes - 1)) {
      TWCR = ((1 << TWINT) | (1 << TWEN) | (1 << TWIE));
    } else {
      TWCR = ((1 << TWEA) | (1 << TWINT) | (1 << TWEN) | (1 << TWIE));
    }
    break;
  case TWI_MASTER_RX_DATA_NACK:
    i2cp->rxbuf[i2cp->rxidx] = TWDR;
    TWCR = ((1 << TWSTO) | (1 << TWINT) | (1 << TWEN));
    wakeup_isr(i2cp, RDY_OK);
  case TWI_MASTER_TX_ADDR_NACK:
  case TWI_MASTER_TX_DATA_NACK:
  case TWI_MASTER_RX_ADDR_NACK:
    i2cp->errors |= I2CD_ACK_FAILURE;
    break;
  case TWI_ARBITRATION_LOST:
    i2cp->errors |= I2CD_ARBITRATION_LOST;
    break;
  case TWI_BUS_ERROR:
    i2cp->errors |= I2CD_BUS_ERROR;
    break;
  default:
    /* FIXME: only gets here if there are other MASTERs in the bus */
    TWCR = ((1 << TWSTO) | (1 << TWINT) | (1 << TWEN));
    wakeup_isr(i2cp, RDY_RESET);
  }

  if (i2cp->errors != I2CD_NO_ERROR) {
    TWCR = ((1 << TWSTO) | (1 << TWINT) | (1 << TWEN));
    wakeup_isr(i2cp, RDY_RESET);
  }

  CH_IRQ_EPILOGUE();
}
#endif /* USE_AVR_I2C */

/*===========================================================================*/
/* Driver exported functions.                                                */
/*===========================================================================*/

/**
 * @brief   Low level I2C driver initialization.
 *
 * @notapi
 */
void i2c_lld_init(void) {
  i2cObjectInit(&I2CD);
}

/**
 * @brief   Configures and activates the I2C peripheral.
 *
 * @param[in] i2cp      pointer to the @p I2CDriver object
 *
 * @notapi
 */
void i2c_lld_start(I2CDriver *i2cp) {

  /* TODO: Test TWI without external pull-ups (use internal) */

  /* Configure prescaler to 1 */
  TWSR &= 0xF8;

  /* Configure baudrate */
  TWBR = ((F_CPU / i2cp->config->clock_speed) - 16) / 2;
}

/**
 * @brief   Deactivates the I2C peripheral.
 *
 * @param[in] i2cp      pointer to the @p I2CDriver object
 *
 * @notapi
 */
void i2c_lld_stop(I2CDriver *i2cp) {

  if (i2cp->state != I2C_STOP) {
    /* Disable TWI subsystem and stop all operations */
    TWCR &= ~(1 << TWEN);
  }
}

/**
 * @brief   Receives data via the I2C bus as master.
 *
 * @param[in] i2cp      pointer to the @p I2CDriver object
 * @param[in] addr      slave device address
 * @param[out] rxbuf    pointer to the receive buffer
 * @param[in] rxbytes   number of bytes to be received
 * @param[in] timeout   the number of ticks before the operation timeouts,
 *                      the following special values are allowed:
 *                      - @a TIME_INFINITE no timeout.
 *                      .
 * @return              The operation status.
 * @retval RDY_OK       if the function succeeded.
 * @retval RDY_RESET    if one or more I2C errors occurred, the errors can
 *                      be retrieved using @p i2cGetErrors().
 * @retval RDY_TIMEOUT  if a timeout occurred before operation end. <b>After a
 *                      timeout the driver must be stopped and restarted
 *                      because the bus is in an uncertain state</b>.
 *
 * @notapi
 */
msg_t i2c_lld_master_receive_timeout(I2CDriver *i2cp, i2caddr_t addr,
                                     uint8_t *rxbuf, size_t rxbytes,
                                     systime_t timeout) {
  i2cp->addr = addr;
  i2cp->txbuf = NULL;
  i2cp->txbytes = 0;
  i2cp->txidx = 0;
  i2cp->rxbuf = rxbuf;
  i2cp->rxbytes = rxbytes;
  i2cp->rxidx = 0;

  /* Send START */
  TWCR = ((1 << TWSTA) | (1 << TWINT) | (1 << TWEN) | (1 << TWIE));

  chSysLock();
  i2cp->thread = chThdSelf();
  chSchGoSleepS(THD_STATE_SUSPENDED);
  chSysUnlock();

  return chThdSelf()->p_u.rdymsg;
}

/**
 * @brief   Transmits data via the I2C bus as master.
 *
 * @param[in] i2cp      pointer to the @p I2CDriver object
 * @param[in] addr      slave device address
 * @param[in] txbuf     pointer to the transmit buffer
 * @param[in] txbytes   number of bytes to be transmitted
 * @param[out] rxbuf    pointer to the receive buffer
 * @param[in] rxbytes   number of bytes to be received
 * @param[in] timeout   the number of ticks before the operation timeouts,
 *                      the following special values are allowed:
 *                      - @a TIME_INFINITE no timeout.
 *                      .
 * @return              The operation status.
 * @retval RDY_OK       if the function succeeded.
 * @retval RDY_RESET    if one or more I2C errors occurred, the errors can
 *                      be retrieved using @p i2cGetErrors().
 * @retval RDY_TIMEOUT  if a timeout occurred before operation end. <b>After a
 *                      timeout the driver must be stopped and restarted
 *                      because the bus is in an uncertain state</b>.
 *
 * @notapi
 */
msg_t i2c_lld_master_transmit_timeout(I2CDriver *i2cp, i2caddr_t addr,
                                      const uint8_t *txbuf, size_t txbytes,
                                      uint8_t *rxbuf, size_t rxbytes,
                                      systime_t timeout) {
  i2cp->addr = addr;
  i2cp->txbuf = txbuf;
  i2cp->txbytes = txbytes;
  i2cp->txidx = 0;
  i2cp->rxbuf = rxbuf;
  i2cp->rxbytes = rxbytes;
  i2cp->rxidx = 0;

  TWCR = ((1 << TWSTA) | (1 << TWINT) | (1 << TWEN) | (1 << TWIE));

  chSysLock();
  i2cp->thread = chThdSelf();
  chSchGoSleepS(THD_STATE_SUSPENDED);
  chSysUnlock();

  return chThdSelf()->p_u.rdymsg;
}

#endif /* HAL_USE_I2C */

/** @} */