/**
*
* When multiple IIC devices attempt to use the bus simultaneously, only
* a single device will be able to keep control as a master. Those devices
* that didn't retain control over the bus are said to have lost arbitration.
* When arbitration is lost, this interrupt occurs sigaling the user that
* the message did not get sent as expected.
*
* This function, at arbitration lost:
* - Disables tx empty, ½ empty and Tx error interrupts
* - Clears any tx empty, ½ empty Rx Full or tx error interrupts
* - Clears Arbitration lost interrupt,
* - Flush Tx FIFO
* - Call StatusHandler callback with the value: XII_ARB_LOST_EVENT
*
* @param InstancePtr is a pointer to the XIic instance to be worked on.
*
* @return
*
* None.
*
* @note
*
* None.
*
******************************************************************************/
static void ArbitrationLostHandler(XIic * InstancePtr)
{
/* Disable tx empty and ½ empty and Tx error interrupts before clearing them
* so they won't occur again
*/
XIic_mDisableIntr(InstancePtr->BaseAddress, XIIC_TX_INTERRUPTS);
/* Clear any tx empty, ½ empty Rx Full or tx error interrupts
*/
XIic_mClearIntr(InstancePtr->BaseAddress, XIIC_TX_INTERRUPTS);
XIic_mFlushTxFifo(InstancePtr);
/* Update Status via StatusHandler callback
*/
InstancePtr->StatusHandler(InstancePtr->StatusCallBackRef,
XII_ARB_LOST_EVENT);
}
/**
*
* This interrupt occurs four different ways: Two as master and two as slave.
* Master:
* <pre>
* (1) Transmitter (IMPLIES AN ERROR)
* The slave receiver did not acknowledge properly.
* (2) Receiver (Implies tx complete)
* Interrupt caused by setting TxAck high in the IIC to indicate to the
* the last byte has been transmitted.
* </pre>
*
* Slave:
* <pre>
* (3) Transmitter (Implies tx complete)
* Interrupt caused by master device indicating last byte of the message
* has been transmitted.
* (4) Receiver (IMPLIES AN ERROR)
* Interrupt caused by setting TxAck high in the IIC to indicate Rx
* IIC had a problem - set by this device and condition already known
* and interrupt is not enabled.
* </pre>
*
* This interrupt is enabled during Master send and receive and disabled
* when this device knows it is going to send a negative acknowledge (Ack = No).
*
* Signals user of Tx error via status callback sending: XII_TX_ERROR_EVENT
*
* When MasterRecv has no message to send and only receives one byte of data
* from the salve device, the TxError must be enabled to catch addressing
* errors, yet there is not opportunity to disable TxError when there is no
* data to send allowing disabling on last byte. When the slave sends the
* only byte the NOAck causes a Tx Error. To disregard this as no real error,
* when there is data in the Receive FIFO/register then the error was not
* a device address write error, but a NOACK read error - to be ignored.
* To work with or without FIFO's, the Rx Data interrupt is used to indicate
* data is in the rx register.
*
* @param InstancePtr is a pointer to the XIic instance to be worked on.
*
* @return
*
* None.
*
* @note
*
* No action is required to clear this interrupt in the device as it is a
* pulse. The interrupt need only be cleared in the IpIf interface.
*
******************************************************************************/
static void TxErrorHandler(XIic * InstancePtr)
{
u32 IntrStatus;
u8 CntlReg;
/* When Sending as a slave, Tx error signals end of msg. Not Addressed As
* Slave will handle the callbacks. this is used to only flush the Tx fifo.
* The addressed as slave bit is gone as soon as the bus has been released
* such that the buffer pointers are used to determine the direction of
* transfer (send or receive).
*/
if (InstancePtr->RecvBufferPtr == NULL) {
/* Master Receiver finished reading message. Flush Tx fifo to remove an
* 0xFF that was written to prevent bus throttling, and disable all
* transmit and receive interrupts
*/
XIic_mFlushTxFifo(InstancePtr);
XIic_mDisableIntr(InstancePtr->BaseAddress,
XIIC_TX_RX_INTERRUPTS);
/* If operating in Master mode, call status handler to indicate
* NOACK occured
*/
CntlReg =
XIo_In8(InstancePtr->BaseAddress + XIIC_CR_REG_OFFSET);
if ((CntlReg & XIIC_CR_MSMS_MASK) != 0) {
InstancePtr->StatusHandler(InstancePtr->
StatusCallBackRef,
XII_SLAVE_NO_ACK_EVENT);
}
return;
}
/* Data in the receive register from either master or slave receive
* When:slave, indicates master sent last byte, message completed.
* When:master, indicates a master Receive with one byte received. When a
* byte is in Rx reg then the Tx error indicates the Rx data was recovered
* normally Tx errors are not enabled such that this should not occur.
*/
IntrStatus = XIIC_READ_IISR(InstancePtr->BaseAddress);
if (IntrStatus & XIIC_INTR_RX_FULL_MASK) {
/* Rx Reg/FIFO has data, Disable tx error interrupts */
XIic_mDisableIntr(InstancePtr->BaseAddress,
XIIC_INTR_TX_ERROR_MASK);
return;
}
XIic_mFlushTxFifo(InstancePtr);
/* Disable and clear tx empty, ½ empty, Rx Full or tx error interrupts
*/
XIic_mDisableIntr(InstancePtr->BaseAddress, XIIC_TX_RX_INTERRUPTS);
XIic_mClearIntr(InstancePtr->BaseAddress, XIIC_TX_RX_INTERRUPTS);
/* Clear MSMS as on TX error when Rxing, the bus will be
* stopped but MSMS bit is still set. Reset to proper state
*/
CntlReg = XIo_In8(InstancePtr->BaseAddress + XIIC_CR_REG_OFFSET);
CntlReg &= ~XIIC_CR_MSMS_MASK;
XIo_Out8(InstancePtr->BaseAddress + XIIC_CR_REG_OFFSET, CntlReg);
/* set FIFO occupancy depth = 1 so that the first byte will throttle
* next recieve msg
*/
XIo_Out8(InstancePtr->BaseAddress + XIIC_RFD_REG_OFFSET, 0);
/* make event callback */
InstancePtr->StatusHandler(InstancePtr->StatusCallBackRef,
XII_SLAVE_NO_ACK_EVENT);
}
/**
*
* This function is called when the receive register is full. The number
* of bytes received to cause the interrupt is adjustable using the Receive FIFO
* Depth register. The number of bytes in the register is read in the Receive
* FIFO occupancy register. Both these registers are zero based values (0-15)
* such that a value of zero indicates 1 byte.
*
* For a Master Receiver to properly signal the end of a message, the data must
* be read in up to the message length - 1, where control register bits will be
* set for bus controls to occur on reading of the last byte.
*
* @param InstancePtr is a pointer to the XIic instance to be worked on.
*
* @return
*
* None.
*
* @note
*
* None.
*
******************************************************************************/
static void RecvMasterData(XIic * InstancePtr)
{
u8 LoopCnt;
int BytesInFifo;
int BytesToRead;
u8 CntlReg;
/* Device is a master receiving, get the contents of the control register
* and determine the number of bytes in fifo to be read out
*/
CntlReg = XIo_In8(InstancePtr->BaseAddress + XIIC_CR_REG_OFFSET);
BytesInFifo = XIo_In8(InstancePtr->BaseAddress + XIIC_RFO_REG_OFFSET)
+ 1;
/* If data in FIFO holds all data to be retrieved - 1, set NOACK and
* disable the tx error
*/
if ((InstancePtr->RecvByteCount - BytesInFifo) == 1) {
/* Disable tx error interrupt to prevent interrupt
* as this device will cause it when it set NO ACK next
*/
XIic_mDisableIntr(InstancePtr->BaseAddress,
XIIC_INTR_TX_ERROR_MASK);
XIic_mClearIntr(InstancePtr->BaseAddress,
XIIC_INTR_TX_ERROR_MASK);
/* Write control reg with NO ACK allowing last byte to
* have the No ack set to indicate to slave last byte read.
*/
XIo_Out8(InstancePtr->BaseAddress + XIIC_CR_REG_OFFSET,
(CntlReg | XIIC_CR_NO_ACK_MASK));
/* Read one byte to clear a place for the last byte to be read
* which will set the NO ACK
*/
XIic_mReadRecvByte(InstancePtr);
}
/* If data in FIFO is all the data to be received then get the data
* and also leave the device in a good state for the next transaction
*/
else if ((InstancePtr->RecvByteCount - BytesInFifo) == 0) {
/* If repeated start option is off then the master should stop
* using the bus, otherwise hold the bus, setting repeated start
* stops the slave from transmitting data when the FIFO is read
*/
if ((InstancePtr->Options & XII_REPEATED_START_OPTION) == 0) {
CntlReg &= ~XIIC_CR_MSMS_MASK;
} else {
CntlReg |= XIIC_CR_REPEATED_START_MASK;
}
XIo_Out8(InstancePtr->BaseAddress + XIIC_CR_REG_OFFSET,
CntlReg);
/* Read data from the FIFO then set zero based FIFO read depth for a byte
*/
for (LoopCnt = 0; LoopCnt < BytesInFifo; LoopCnt++) {
XIic_mReadRecvByte(InstancePtr);
}
XIo_Out8(InstancePtr->BaseAddress + XIIC_RFD_REG_OFFSET, 0);
/* Disable Rx full interrupt and write the control reg with ACK allowing
* next byte sent to be acknowledged automatically
*/
XIic_mDisableIntr(InstancePtr->BaseAddress,
XIIC_INTR_RX_FULL_MASK);
XIo_Out8(InstancePtr->BaseAddress + XIIC_CR_REG_OFFSET,
(CntlReg & ~XIIC_CR_NO_ACK_MASK));
/* Send notification of msg Rx complete in RecvHandler callback
*/
InstancePtr->RecvHandler(InstancePtr->RecvCallBackRef, 0);
} else {
/* Fifo data not at n-1, read all but the last byte of data from the
* slave, if more than a FIFO full yet to receive read a FIFO full
*/
BytesToRead = InstancePtr->RecvByteCount - BytesInFifo - 1;
if (BytesToRead > IIC_RX_FIFO_DEPTH) {
BytesToRead = IIC_RX_FIFO_DEPTH;
}
/* Read in data from the FIFO */
for (LoopCnt = 0; LoopCnt < BytesToRead; LoopCnt++) {
XIic_mReadRecvByte(InstancePtr);
}
}
}
