/* ttyhandler.c - ttyhandler */

#include 

/*------------------------------------------------------------------------
 *  ttyhandler  -  Handle an interrupt for a tty (serial) device
 *------------------------------------------------------------------------
 */
void ttyhandler(
                int32   arg     /* Interrupt handler argument   */
                )
{
        struct  dentry  *devptr;        /* Address of device control blk*/
        struct  ttycblk *typtr;         /* Pointer to ttytab entry      */      
        struct  uart_csreg *csrptr;     /* Address of UART's CSR        */
        byte    iir = 0;                /* Interrupt identification     */


        /* Get CSR address of the device (assume console for now) */

        devptr = (struct dentry *) arg;
        csrptr = (struct uart_csreg *) devptr->dvcsr;

        /* Obtain a pointer to the tty control block */

        typtr = &ttytab[ devptr->dvminor ];

        /* Decode hardware interrupt request from UART device */

        /* Check interrupt identification register */
        iir = csrptr->iir;
        if (iir & UART_IIR_IRQ) {
                return;
        }

        /* Decode the interrupt cause based upon the value extracted    */
        /*  from the UART interrupt identification register.  Clear     */
        /*  the interrupt source and perform the appropriate handling   */
        /*  to coordinate with the upper half of the driver             */

        /* Decode the interrupt cause */

        iir &= UART_IIR_IDMASK;         /* Mask off the interrupt ID */
        switch (iir) {

            /* Receiver line status interrupt (error) */

            case UART_IIR_RLSI:
                return;

            /* Receiver data available or timed out */

            case UART_IIR_RDA:
            case UART_IIR_RTO:

                resched_cntl(DEFER_START);

                /* While chars avail. in UART buffer, call ttyhandle_in */

                while ( (csrptr->lsr & UART_LSR_DR) != 0) {
                        ttyhandle_in(typtr, csrptr);
                }

                resched_cntl(DEFER_STOP);

                return;

            /* Transmitter output FIFO is empty (i.e., ready for more)  */

            case UART_IIR_THRE:
                ttyhandle_out(typtr, csrptr);
                return;

            /* Modem status change (simply ignore) */

            case UART_IIR_MSC:
                return;
            }
}