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

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/*
ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
2011,2012 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 */
/** @} */
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