// initializes the spi0 for supplied configuration
static void raspicomm_max3140_apply_config(void)
{
mutex_lock ( &SpiLock );
raspicomm_spi0_send( SpiConfig );
raspicomm_spi0_send( 0x8600 ); // enable receive by disabling RTS (TE set so that no data is sent)
mutex_unlock ( &SpiLock );
}
// called by the kernel after write() is called from userspace and write_room() returns > 0
static int raspicommDriver_write(struct tty_struct* tty,
const unsigned char* buf,
int count)
{
int bytes_written = 0;
int receive;
// int txdata;
#if DEBUG
printk(KERN_INFO "raspicomm: raspicommDriver_write(count=%i)\n", count);
#endif
mutex_lock(&SpiLock);
// insert them into the transmit queue
for (bytes_written = 0; bytes_written < count; bytes_written++)
{
if (queue_enqueue(&TxQueue, buf[bytes_written]) < 0)
break;
}
// SpiConfig = SpiConfig | 0xC800; // set bit 15, 14, TM bit
SpiConfig = SpiConfig | MAX3140_UART_T | MAX3140_UART_R | MAX3140_UART_TM;
receive = raspicomm_spi0_send( SpiConfig );
if (receive & MAX3140_UART_T) // transmit buffer is ready to accept data
{
// txdata = queue_dequeue(&TxQueue);
// javicient
char aux = queue_dequeue(&TxQueue);
raspicomm_spi0_send( 0x8000 | aux | raspicomm_max3140_get_parity_flag(aux));
// raspicomm_spi0_send( 0x8000 | txdata | raspicomm_max3140_get_parity_flag((char)txdata));
}
mutex_unlock(&SpiLock);
return bytes_written;
}
// the bottom half of the irq handler, is allowed to get some sleep
void raspicomm_irq_work_queue_handler(void *arg)
{
int rxdata, txdata;
// lock on the transmit queue
mutex_lock( &SpiLock );
// #if DEBUG
// printk( KERN_INFO "raspicomm: raspicomm_irq_handler (%i)", irq);
// #endif
// issue a read command to discover the cause of the interrupt
rxdata = raspicomm_spi0_send(0);
// DEBUG: log data
// #if DEBUG
// printk( KERN_INFO "raspicomm: raspicomm_irq_handler rxdata=%X", rxdata);
// #endif
// read the data
while(rxdata & MAX3140_UART_R) // while we are receiving
{
// handle the received data
raspicomm_rs485_received( OpenTTY, rxdata & 0x00FF );
// get the next rxdata
rxdata = raspicomm_spi0_send(0);
}
// write the data
if ((rxdata & MAX3140_UART_T) && (SpiConfig & MAX3140_UART_TM))
{
if (!queue_is_empty(&TxQueue))
{
txdata = queue_dequeue(&TxQueue);
// parity flag
// raspicomm_spi0_send( MAX3140_UART_TM | txdata | raspicomm_max3140_get_parity_flag((char)txdata) );
// raspicomm_spi0_send( 0x8000| txdata );
raspicomm_spi0_send( MAX3140_UART_R | txdata );
}
else
{
// mask transmit buffer empty interrupt
SpiConfig = SpiConfig & ~0x0800; // clear the TM bit
SpiConfig = SpiConfig | 0xc000; // set bits 15 and 14
raspicomm_spi0_send(SpiConfig);
// usleep(SwBacksleep);
udelay(SwBacksleep); // there is no usleep function in the kernel
raspicomm_spi0_send(0x8600); // enable receive by disabling RTS (TE set so that no data is sent)
}
}
// unlock the transmit queue
mutex_unlock( &SpiLock );
}