// SPDX-License-Identifier: GPL-2.0+
/************************************************************************
 * Copyright 2003 Digi International (www.digi.com)
 *
 * Copyright (C) 2004 IBM Corporation. All rights reserved.
 *
 * Contact Information:
 * Scott H Kilau <Scott_Kilau@digi.com>
 * Wendy Xiong   <wendyx@us.ibm.com>
 *
 ***********************************************************************/
#include <linux/delay.h>        /* For udelay */
#include <linux/serial_reg.h>   /* For the various UART offsets */
#include <linux/tty.h>
#include <linux/pci.h>
#include <asm/io.h>

#include "jsm.h"                /* Driver main header file */

static u32 jsm_offset_table[8] = { 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80 };

/*
 * This function allows calls to ensure that all outstanding
 * PCI writes have been completed, by doing a PCI read against
 * a non-destructive, read-only location on the Neo card.
 *
 * In this case, we are reading the DVID (Read-only Device Identification)
 * value of the Neo card.
 */
static inline void neo_pci_posting_flush(struct jsm_board *bd)
{
      readb(bd->re_map_membase + 0x8D);
}

static void neo_set_cts_flow_control(struct jsm_channel *ch)
{
        u8 ier, efr;
        ier = readb(&ch->ch_neo_uart->ier);
        efr = readb(&ch->ch_neo_uart->efr);

        jsm_dbg(PARAM, &ch->ch_bd->pci_dev, "Setting CTSFLOW\n");

        /* Turn on auto CTS flow control */
        ier |= (UART_17158_IER_CTSDSR);
        efr |= (UART_17158_EFR_ECB | UART_17158_EFR_CTSDSR);

        /* Turn off auto Xon flow control */
        efr &= ~(UART_17158_EFR_IXON);

        /* Why? Becuz Exar's spec says we have to zero it out before setting it */
        writeb(0, &ch->ch_neo_uart->efr);

        /* Turn on UART enhanced bits */
        writeb(efr, &ch->ch_neo_uart->efr);

        /* Turn on table D, with 8 char hi/low watermarks */
        writeb((UART_17158_FCTR_TRGD | UART_17158_FCTR_RTS_4DELAY), &ch->ch_neo_uart->fctr);

        /* Feed the UART our trigger levels */
        writeb(8, &ch->ch_neo_uart->tfifo);
        ch->ch_t_tlevel = 8;

        writeb(ier, &ch->ch_neo_uart->ier);
}

static void neo_set_rts_flow_control(struct jsm_channel *ch)
{
        u8 ier, efr;
        ier = readb(&ch->ch_neo_uart->ier);
        efr = readb(&ch->ch_neo_uart->efr);

        jsm_dbg(PARAM, &ch->ch_bd->pci_dev, "Setting RTSFLOW\n");

        /* Turn on auto RTS flow control */
        ier |= (UART_17158_IER_RTSDTR);
        efr |= (UART_17158_EFR_ECB | UART_17158_EFR_RTSDTR);

        /* Turn off auto Xoff flow control */
        ier &= ~(UART_17158_IER_XOFF);
        efr &= ~(UART_17158_EFR_IXOFF);

        /* Why? Becuz Exar's spec says we have to zero it out before setting it */
        writeb(0, &ch->ch_neo_uart->efr);

        /* Turn on UART enhanced bits */
        writeb(efr, &ch->ch_neo_uart->efr);

        writeb((UART_17158_FCTR_TRGD | UART_17158_FCTR_RTS_4DELAY), &ch->ch_neo_uart->fctr);
        ch->ch_r_watermark = 4;

        writeb(56, &ch->ch_neo_uart->rfifo);
        ch->ch_r_tlevel = 56;

        writeb(ier, &ch->ch_neo_uart->ier);

        /*
         * From the Neo UART spec sheet:
         * The auto RTS/DTR function must be started by asserting
         * RTS/DTR# output pin (MCR bit-0 or 1 to logic 1 after
         * it is enabled.
         */
        ch->ch_mostat |= (UART_MCR_RTS);
}


static void neo_set_ixon_flow_control(struct jsm_channel *ch)
{
        u8 ier, efr;
        ier = readb(&ch->ch_neo_uart->ier);
        efr = readb(&ch->ch_neo_uart->efr);

        jsm_dbg(PARAM, &ch->ch_bd->pci_dev, "Setting IXON FLOW\n");

        /* Turn off auto CTS flow control */
        ier &= ~(UART_17158_IER_CTSDSR);
        efr &= ~(UART_17158_EFR_CTSDSR);

        /* Turn on auto Xon flow control */
        efr |= (UART_17158_EFR_ECB | UART_17158_EFR_IXON);

        /* Why? Becuz Exar's spec says we have to zero it out before setting it */
        writeb(0, &ch->ch_neo_uart->efr);

        /* Turn on UART enhanced bits */
        writeb(efr, &ch->ch_neo_uart->efr);

        writeb((UART_17158_FCTR_TRGD | UART_17158_FCTR_RTS_8DELAY), &ch->ch_neo_uart->fctr);
        ch->ch_r_watermark = 4;

        writeb(32, &ch->ch_neo_uart->rfifo);
        ch->ch_r_tlevel = 32;

        /* Tell UART what start/stop chars it should be looking for */
        writeb(ch->ch_startc, &ch->ch_neo_uart->xonchar1);
        writeb(0, &ch->ch_neo_uart->xonchar2);

        writeb(ch->ch_stopc, &ch->ch_neo_uart->xoffchar1);
        writeb(0, &ch->ch_neo_uart->xoffchar2);

        writeb(ier, &ch->ch_neo_uart->ier);
}

static void neo_set_ixoff_flow_control(struct jsm_channel *ch)
{
        u8 ier, efr;
        ier = readb(&ch->ch_neo_uart->ier);
        efr = readb(&ch->ch_neo_uart->efr);

        jsm_dbg(PARAM, &ch->ch_bd->pci_dev, "Setting IXOFF FLOW\n");

        /* Turn off auto RTS flow control */
        ier &= ~(UART_17158_IER_RTSDTR);
        efr &= ~(UART_17158_EFR_RTSDTR);

        /* Turn on auto Xoff flow control */
        ier |= (UART_17158_IER_XOFF);
        efr |= (UART_17158_EFR_ECB | UART_17158_EFR_IXOFF);

        /* Why? Becuz Exar's spec says we have to zero it out before setting it */
        writeb(0, &ch->ch_neo_uart->efr);

        /* Turn on UART enhanced bits */
        writeb(efr, &ch->ch_neo_uart->efr);

        /* Turn on table D, with 8 char hi/low watermarks */
        writeb((UART_17158_FCTR_TRGD | UART_17158_FCTR_RTS_8DELAY), &ch->ch_neo_uart->fctr);

        writeb(8, &ch->ch_neo_uart->tfifo);
        ch->ch_t_tlevel = 8;

        /* Tell UART what start/stop chars it should be looking for */
        writeb(ch->ch_startc, &ch->ch_neo_uart->xonchar1);
        writeb(0, &ch->ch_neo_uart->xonchar2);

        writeb(ch->ch_stopc, &ch->ch_neo_uart->xoffchar1);
        writeb(0, &ch->ch_neo_uart->xoffchar2);

        writeb(ier, &ch->ch_neo_uart->ier);
}

static void neo_set_no_input_flow_control(struct jsm_channel *ch)
{
        u8 ier, efr;
        ier = readb(&ch->ch_neo_uart->ier);
        efr = readb(&ch->ch_neo_uart->efr);

        jsm_dbg(PARAM, &ch->ch_bd->pci_dev, "Unsetting Input FLOW\n");

        /* Turn off auto RTS flow control */
        ier &= ~(UART_17158_IER_RTSDTR);
        efr &= ~(UART_17158_EFR_RTSDTR);

        /* Turn off auto Xoff flow control */
        ier &= ~(UART_17158_IER_XOFF);
        if (ch->ch_c_iflag & IXON)
                efr &= ~(UART_17158_EFR_IXOFF);
        else
                efr &= ~(UART_17158_EFR_ECB | UART_17158_EFR_IXOFF);

        /* Why? Becuz Exar's spec says we have to zero it out before setting it */
        writeb(0, &ch->ch_neo_uart->efr);

        /* Turn on UART enhanced bits */
        writeb(efr, &ch->ch_neo_uart->efr);

        /* Turn on table D, with 8 char hi/low watermarks */
        writeb((UART_17158_FCTR_TRGD | UART_17158_FCTR_RTS_8DELAY), &ch->ch_neo_uart->fctr);

        ch->ch_r_watermark = 0;

        writeb(16, &ch->ch_neo_uart->tfifo);
        ch->ch_t_tlevel = 16;

        writeb(16, &ch->ch_neo_uart->rfifo);
        ch->ch_r_tlevel = 16;

        writeb(ier, &ch->ch_neo_uart->ier);
}

static void neo_set_no_output_flow_control(struct jsm_channel *ch)
{
        u8 ier, efr;
        ier = readb(&ch->ch_neo_uart->ier);
        efr = readb(&ch->ch_neo_uart->efr);

        jsm_dbg(PARAM, &ch->ch_bd->pci_dev, "Unsetting Output FLOW\n");

        /* Turn off auto CTS flow control */
        ier &= ~(UART_17158_IER_CTSDSR);
        efr &= ~(UART_17158_EFR_CTSDSR);

        /* Turn off auto Xon flow control */
        if (ch->ch_c_iflag & IXOFF)
                efr &= ~(UART_17158_EFR_IXON);
        else
                efr &= ~(UART_17158_EFR_ECB | UART_17158_EFR_IXON);

        /* Why? Becuz Exar's spec says we have to zero it out before setting it */
        writeb(0, &ch->ch_neo_uart->efr);

        /* Turn on UART enhanced bits */
        writeb(efr, &ch->ch_neo_uart->efr);

        /* Turn on table D, with 8 char hi/low watermarks */
        writeb((UART_17158_FCTR_TRGD | UART_17158_FCTR_RTS_8DELAY), &ch->ch_neo_uart->fctr);

        ch->ch_r_watermark = 0;

        writeb(16, &ch->ch_neo_uart->tfifo);
        ch->ch_t_tlevel = 16;

        writeb(16, &ch->ch_neo_uart->rfifo);
        ch->ch_r_tlevel = 16;

        writeb(ier, &ch->ch_neo_uart->ier);
}

static inline void neo_set_new_start_stop_chars(struct jsm_channel *ch)
{

        /* if hardware flow control is set, then skip this whole thing */
        if (ch->ch_c_cflag & CRTSCTS)
                return;

        jsm_dbg(PARAM, &ch->ch_bd->pci_dev, "start\n");

        /* Tell UART what start/stop chars it should be looking for */
        writeb(ch->ch_startc, &ch->ch_neo_uart->xonchar1);
        writeb(0, &ch->ch_neo_uart->xonchar2);

        writeb(ch->ch_stopc, &ch->ch_neo_uart->xoffchar1);
        writeb(0, &ch->ch_neo_uart->xoffchar2);
}

static void neo_copy_data_from_uart_to_queue(struct jsm_channel *ch)
{
        int qleft = 0;
        u8 linestatus = 0;
        u8 error_mask = 0;
        int n = 0;
        int total = 0;
        u16 head;
        u16 tail;

        /* cache head and tail of queue */
        head = ch->ch_r_head & RQUEUEMASK;
        tail = ch->ch_r_tail & RQUEUEMASK;

        /* Get our cached LSR */
        linestatus = ch->ch_cached_lsr;
        ch->ch_cached_lsr = 0;

        /* Store how much space we have left in the queue */
        qleft = tail - head - 1;
        if (qleft < 0)
                qleft += RQUEUEMASK + 1;

        /*
         * If the UART is not in FIFO mode, force the FIFO copy to
         * NOT be run, by setting total to 0.
         *
         * On the other hand, if the UART IS in FIFO mode, then ask
         * the UART to give us an approximation of data it has RX'ed.
         */
        if (!(ch->ch_flags & CH_FIFO_ENABLED))
                total = 0;
        else {
                total = readb(&ch->ch_neo_uart->rfifo);

                /*
                 * EXAR chip bug - RX FIFO COUNT - Fudge factor.
                 *
                 * This resolves a problem/bug with the Exar chip that sometimes
                 * returns a bogus value in the rfifo register.
                 * The count can be any where from 0-3 bytes "off".
                 * Bizarre, but true.
                 */
                total -= 3;
        }

        /*
         * Finally, bound the copy to make sure we don't overflow
         * our own queue...
         * The byte by byte copy loop below this loop this will
         * deal with the queue overflow possibility.
         */
        total = min(total, qleft);

        while (total > 0) {
                /*
                 * Grab the linestatus register, we need to check
                 * to see if there are any errors in the FIFO.
                 */
                linestatus = readb(&ch->ch_neo_uart->lsr);

                /*
                 * Break out if there is a FIFO error somewhere.
                 * This will allow us to go byte by byte down below,
                 * finding the exact location of the error.
                 */
                if (linestatus & UART_17158_RX_FIFO_DATA_ERROR)
                        break;

                /* Make sure we don't go over the end of our queue */
                n = min(((u32) total), (RQUEUESIZE - (u32) head));

                /*
                 * Cut down n even further if needed, this is to fix
                 * a problem with memcpy_fromio() with the Neo on the
                 * IBM pSeries platform.
                 * 15 bytes max appears to be the magic number.
                 */
                n = min((u32) n, (u32) 12);

                /*
                 * Since we are grabbing the linestatus register, which
                 * will reset some bits after our read, we need to ensure
                 * we don't miss our TX FIFO emptys.
                 */
                if (linestatus & (UART_LSR_THRE | UART_17158_TX_AND_FIFO_CLR))
                        ch->ch_flags |= (CH_TX_FIFO_EMPTY | CH_TX_FIFO_LWM);

                linestatus = 0;

                /* Copy data from uart to the queue */
                memcpy_fromio(ch->ch_rqueue + head, &ch->ch_neo_uart->txrxburst, n);
                /*
                 * Since RX_FIFO_DATA_ERROR was 0, we are guaranteed
                 * that all the data currently in the FIFO is free of
                 * breaks and parity/frame/orun errors.
                 */
                memset(ch->ch_equeue + head, 0, n);

                /* Add to and flip head if needed */
                head = (head + n) & RQUEUEMASK;
                total -= n;
                qleft -= n;
                ch->ch_rxcount += n;
        }

        /*
         * Create a mask to determine whether we should
         * insert the character (if any) into our queue.
         */
        if (ch->ch_c_iflag & IGNBRK)
                error_mask |= UART_LSR_BI;

        /*
         * Now cleanup any leftover bytes still in the UART.
         * Also deal with any possible queue overflow here as well.
         */
        while (1) {

                /*
                 * Its possible we have a linestatus from the loop above
                 * this, so we "OR" on any extra bits.
                 */
                linestatus |= readb(&ch->ch_neo_uart->lsr);

                /*
                 * If the chip tells us there is no more data pending to
                 * be read, we can then leave.
                 * But before we do, cache the linestatus, just in case.
                 */
                if (!(linestatus & UART_LSR_DR)) {
                        ch->ch_cached_lsr = linestatus;
                        break;
                }

                /* No need to store this bit */
                linestatus &= ~UART_LSR_DR;

                /*
                 * Since we are grabbing the linestatus register, which
                 * will reset some bits after our read, we need to ensure
                 * we don't miss our TX FIFO emptys.
                 */
                if (linestatus & (UART_LSR_THRE | UART_17158_TX_AND_FIFO_CLR)) {
                        linestatus &= ~(UART_LSR_THRE | UART_17158_TX_AND_FIFO_CLR);
                        ch->ch_flags |= (CH_TX_FIFO_EMPTY | CH_TX_FIFO_LWM);
                }

                /*
                 * Discard character if we are ignoring the error mask.
                 */
                if (linestatus & error_mask) {
                        u8 discard;
                        linestatus = 0;
                        memcpy_fromio(&discard, &ch->ch_neo_uart->txrxburst, 1);
                        continue;
                }

                /*
                 * If our queue is full, we have no choice but to drop some data.
                 * The assumption is that HWFLOW or SWFLOW should have stopped
                 * things way way before we got to this point.
                 *
                 * I decided that I wanted to ditch the oldest data first,
                 * I hope thats okay with everyone? Yes? Good.
                 */
                while (qleft < 1) {
                        jsm_dbg(READ, &ch->ch_bd->pci_dev,
                                "Queue full, dropping DATA:%x LSR:%x\n",
                                ch->ch_rqueue[tail], ch->ch_equeue[tail]);

                        ch->ch_r_tail = tail = (tail + 1) & RQUEUEMASK;
                        ch->ch_err_overrun++;
                        qleft++;
                }

                memcpy_fromio(ch->ch_rqueue + head, &ch->ch_neo_uart->txrxburst, 1);
                ch->ch_equeue[head] = (u8) linestatus;

                jsm_dbg(READ, &ch->ch_bd->pci_dev, "DATA/LSR pair: %x %x\n",
                        ch->ch_rqueue[head], ch->ch_equeue[head]);

                /* Ditch any remaining linestatus value. */
                linestatus = 0;

                /* Add to and flip head if needed */
                head = (head + 1) & RQUEUEMASK;

                qleft--;
                ch->ch_rxcount++;
        }

        /*
         * Write new final heads to channel structure.
         */
        ch->ch_r_head = head & RQUEUEMASK;
        ch->ch_e_head = head & EQUEUEMASK;
        jsm_input(ch);
}

static void neo_copy_data_from_queue_to_uart(struct jsm_channel *ch)
{
        struct tty_port *tport;
        unsigned char *tail;
        unsigned char c;
        int n;
        int s;
        int qlen;
        u32 len_written = 0;

        if (!ch)
                return;

        tport = &ch->uart_port.state->port;

        /* No data to write to the UART */
        if (kfifo_is_empty(&tport->xmit_fifo))
                return;

        /* If port is "stopped", don't send any data to the UART */
        if ((ch->ch_flags & CH_STOP) || (ch->ch_flags & CH_BREAK_SENDING))
                return;
        /*
         * If FIFOs are disabled. Send data directly to txrx register
         */
        if (!(ch->ch_flags & CH_FIFO_ENABLED)) {
                u8 lsrbits = readb(&ch->ch_neo_uart->lsr);

                ch->ch_cached_lsr |= lsrbits;
                if (ch->ch_cached_lsr & UART_LSR_THRE) {
                        ch->ch_cached_lsr &= ~(UART_LSR_THRE);

                        WARN_ON_ONCE(!kfifo_get(&tport->xmit_fifo, &c));
                        writeb(c, &ch->ch_neo_uart->txrx);
                        jsm_dbg(WRITE, &ch->ch_bd->pci_dev, "Tx data: %x\n", c);
                        ch->ch_txcount++;
                }
                return;
        }

        /*
         * We have to do it this way, because of the EXAR TXFIFO count bug.
         */
        if (!(ch->ch_flags & (CH_TX_FIFO_EMPTY | CH_TX_FIFO_LWM)))
                return;

        n = UART_17158_TX_FIFOSIZE - ch->ch_t_tlevel;
        qlen = kfifo_len(&tport->xmit_fifo);

        /* Find minimum of the FIFO space, versus queue length */
        n = min(n, qlen);

        while (n > 0) {
                s = kfifo_out_linear_ptr(&tport->xmit_fifo, &tail, n);
                if (s <= 0)
                        break;

                memcpy_toio(&ch->ch_neo_uart->txrxburst, tail, s);
                kfifo_skip_count(&tport->xmit_fifo, s);
                n -= s;
                ch->ch_txcount += s;
                len_written += s;
        }

        if (len_written >= ch->ch_t_tlevel)
                ch->ch_flags &= ~(CH_TX_FIFO_EMPTY | CH_TX_FIFO_LWM);

        if (kfifo_is_empty(&tport->xmit_fifo))
                uart_write_wakeup(&ch->uart_port);
}

static void neo_parse_modem(struct jsm_channel *ch, u8 signals)
{
        u8 msignals = signals;

        jsm_dbg(MSIGS, &ch->ch_bd->pci_dev,
                "neo_parse_modem: port: %d msignals: %x\n",
                ch->ch_portnum, msignals);

        /* Scrub off lower bits. They signify delta's, which I don't care about */
        /* Keep DDCD and DDSR though */
        msignals &= 0xf8;

        if (msignals & UART_MSR_DDCD)
                uart_handle_dcd_change(&ch->uart_port, msignals & UART_MSR_DCD);
        if (msignals & UART_MSR_DDSR)
                uart_handle_cts_change(&ch->uart_port, msignals & UART_MSR_CTS);
        if (msignals & UART_MSR_DCD)
                ch->ch_mistat |= UART_MSR_DCD;
        else
                ch->ch_mistat &= ~UART_MSR_DCD;

        if (msignals & UART_MSR_DSR)
                ch->ch_mistat |= UART_MSR_DSR;
        else
                ch->ch_mistat &= ~UART_MSR_DSR;

        if (msignals & UART_MSR_RI)
                ch->ch_mistat |= UART_MSR_RI;
        else
                ch->ch_mistat &= ~UART_MSR_RI;

        if (msignals & UART_MSR_CTS)
                ch->ch_mistat |= UART_MSR_CTS;
        else
                ch->ch_mistat &= ~UART_MSR_CTS;

        jsm_dbg(MSIGS, &ch->ch_bd->pci_dev,
                "Port: %d DTR: %d RTS: %d CTS: %d DSR: %d " "RI: %d CD: %d\n",
                ch->ch_portnum,
                !!((ch->ch_mistat | ch->ch_mostat) & UART_MCR_DTR),
                !!((ch->ch_mistat | ch->ch_mostat) & UART_MCR_RTS),
                !!((ch->ch_mistat | ch->ch_mostat) & UART_MSR_CTS),
                !!((ch->ch_mistat | ch->ch_mostat) & UART_MSR_DSR),
                !!((ch->ch_mistat | ch->ch_mostat) & UART_MSR_RI),
                !!((ch->ch_mistat | ch->ch_mostat) & UART_MSR_DCD));
}

/* Make the UART raise any of the output signals we want up */
static void neo_assert_modem_signals(struct jsm_channel *ch)
{
        if (!ch)
                return;

        writeb(ch->ch_mostat, &ch->ch_neo_uart->mcr);

        /* flush write operation */
        neo_pci_posting_flush(ch->ch_bd);
}

/*
 * Flush the WRITE FIFO on the Neo.
 *
 * NOTE: Channel lock MUST be held before calling this function!
 */
static void neo_flush_uart_write(struct jsm_channel *ch)
{
        u8 tmp = 0;
        int i = 0;

        if (!ch)
                return;

        writeb((UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_XMIT), &ch->ch_neo_uart->isr_fcr);

        for (i = 0; i < 10; i++) {

                /* Check to see if the UART feels it completely flushed the FIFO. */
                tmp = readb(&ch->ch_neo_uart->isr_fcr);
                if (tmp & UART_FCR_CLEAR_XMIT) {
                        jsm_dbg(IOCTL, &ch->ch_bd->pci_dev,
                                "Still flushing TX UART... i: %d\n", i);
                        udelay(10);
                }
                else
                        break;
        }

        ch->ch_flags |= (CH_TX_FIFO_EMPTY | CH_TX_FIFO_LWM);
}


/*
 * Flush the READ FIFO on the Neo.
 *
 * NOTE: Channel lock MUST be held before calling this function!
 */
static void neo_flush_uart_read(struct jsm_channel *ch)
{
        u8 tmp = 0;
        int i = 0;

        if (!ch)
                return;

        writeb((UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_RCVR), &ch->ch_neo_uart->isr_fcr);

        for (i = 0; i < 10; i++) {

                /* Check to see if the UART feels it completely flushed the FIFO. */
                tmp = readb(&ch->ch_neo_uart->isr_fcr);
                if (tmp & 2) {
                        jsm_dbg(IOCTL, &ch->ch_bd->pci_dev,
                                "Still flushing RX UART... i: %d\n", i);
                        udelay(10);
                }
                else
                        break;
        }
}

/*
 * No locks are assumed to be held when calling this function.
 */
static void neo_clear_break(struct jsm_channel *ch)
{
        unsigned long lock_flags;

        spin_lock_irqsave(&ch->ch_lock, lock_flags);

        /* Turn break off, and unset some variables */
        if (ch->ch_flags & CH_BREAK_SENDING) {
                u8 temp = readb(&ch->ch_neo_uart->lcr);
                writeb((temp & ~UART_LCR_SBC), &ch->ch_neo_uart->lcr);

                ch->ch_flags &= ~(CH_BREAK_SENDING);
                jsm_dbg(IOCTL, &ch->ch_bd->pci_dev,
                        "clear break Finishing UART_LCR_SBC! finished: %lx\n",
                        jiffies);

                /* flush write operation */
                neo_pci_posting_flush(ch->ch_bd);
        }
        spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
}

/*
 * Parse the ISR register.
 */
static void neo_parse_isr(struct jsm_board *brd, u32 port)
{
        struct jsm_channel *ch;
        u8 isr;
        u8 cause;
        unsigned long lock_flags;

        if (!brd)
                return;

        if (port >= brd->maxports)
                return;

        ch = brd->channels[port];
        if (!ch)
                return;

        /* Here we try to figure out what caused the interrupt to happen */
        while (1) {

                isr = readb(&ch->ch_neo_uart->isr_fcr);

                /* Bail if no pending interrupt */
                if (isr & UART_IIR_NO_INT)
                        break;

                /*
                 * Yank off the upper 2 bits, which just show that the FIFO's are enabled.
                 */
                isr &= ~(UART_17158_IIR_FIFO_ENABLED);

                jsm_dbg(INTR, &ch->ch_bd->pci_dev, "%s:%d isr: %x\n",
                        __FILE__, __LINE__, isr);

                if (isr & (UART_17158_IIR_RDI_TIMEOUT | UART_IIR_RDI)) {
                        /* Read data from uart -> queue */
                        neo_copy_data_from_uart_to_queue(ch);

                        /* Call our tty layer to enforce queue flow control if needed. */
                        spin_lock_irqsave(&ch->ch_lock, lock_flags);
                        jsm_check_queue_flow_control(ch);
                        spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
                }

                if (isr & UART_IIR_THRI) {
                        /* Transfer data (if any) from Write Queue -> UART. */
                        spin_lock_irqsave(&ch->ch_lock, lock_flags);
                        ch->ch_flags |= (CH_TX_FIFO_EMPTY | CH_TX_FIFO_LWM);
                        spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
                        neo_copy_data_from_queue_to_uart(ch);
                }

                if (isr & UART_17158_IIR_XONXOFF) {
                        cause = readb(&ch->ch_neo_uart->xoffchar1);

                        jsm_dbg(INTR, &ch->ch_bd->pci_dev,
                                "Port %d. Got ISR_XONXOFF: cause:%x\n",
                                port, cause);

                        /*
                         * Since the UART detected either an XON or
                         * XOFF match, we need to figure out which
                         * one it was, so we can suspend or resume data flow.
                         */
                        spin_lock_irqsave(&ch->ch_lock, lock_flags);
                        if (cause == UART_17158_XON_DETECT) {
                                /* Is output stopped right now, if so, resume it */
                                if (brd->channels[port]->ch_flags & CH_STOP) {
                                        ch->ch_flags &= ~(CH_STOP);
                                }
                                jsm_dbg(INTR, &ch->ch_bd->pci_dev,
                                        "Port %d. XON detected in incoming data\n",
                                        port);
                        }
                        else if (cause == UART_17158_XOFF_DETECT) {
                                if (!(brd->channels[port]->ch_flags & CH_STOP)) {
                                        ch->ch_flags |= CH_STOP;
                                        jsm_dbg(INTR, &ch->ch_bd->pci_dev,
                                                "Setting CH_STOP\n");
                                }
                                jsm_dbg(INTR, &ch->ch_bd->pci_dev,
                                        "Port: %d. XOFF detected in incoming data\n",
                                        port);
                        }
                        spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
                }

                if (isr & UART_17158_IIR_HWFLOW_STATE_CHANGE) {
                        /*
                         * If we get here, this means the hardware is doing auto flow control.
                         * Check to see whether RTS/DTR or CTS/DSR caused this interrupt.
                         */
                        cause = readb(&ch->ch_neo_uart->mcr);

                        /* Which pin is doing auto flow? RTS or DTR? */
                        spin_lock_irqsave(&ch->ch_lock, lock_flags);
                        if ((cause & 0x4) == 0) {
                                if (cause & UART_MCR_RTS)
                                        ch->ch_mostat |= UART_MCR_RTS;
                                else
                                        ch->ch_mostat &= ~(UART_MCR_RTS);
                        } else {
                                if (cause & UART_MCR_DTR)
                                        ch->ch_mostat |= UART_MCR_DTR;
                                else
                                        ch->ch_mostat &= ~(UART_MCR_DTR);
                        }
                        spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
                }

                /* Parse any modem signal changes */
                jsm_dbg(INTR, &ch->ch_bd->pci_dev,
                        "MOD_STAT: sending to parse_modem_sigs\n");
                uart_port_lock_irqsave(&ch->uart_port, &lock_flags);
                neo_parse_modem(ch, readb(&ch->ch_neo_uart->msr));
                uart_port_unlock_irqrestore(&ch->uart_port, lock_flags);
        }
}

static inline void neo_parse_lsr(struct jsm_board *brd, u32 port)
{
        struct jsm_channel *ch;
        int linestatus;
        unsigned long lock_flags;

        if (!brd)
                return;

        if (port >= brd->maxports)
                return;

        ch = brd->channels[port];
        if (!ch)
                return;

        linestatus = readb(&ch->ch_neo_uart->lsr);

        jsm_dbg(INTR, &ch->ch_bd->pci_dev, "%s:%d port: %d linestatus: %x\n",
                __FILE__, __LINE__, port, linestatus);

        ch->ch_cached_lsr |= linestatus;

        if (ch->ch_cached_lsr & UART_LSR_DR) {
                /* Read data from uart -> queue */
                neo_copy_data_from_uart_to_queue(ch);
                spin_lock_irqsave(&ch->ch_lock, lock_flags);
                jsm_check_queue_flow_control(ch);
                spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
        }

        /*
         * This is a special flag. It indicates that at least 1
         * RX error (parity, framing, or break) has happened.
         * Mark this in our struct, which will tell me that I have
         *to do the special RX+LSR read for this FIFO load.
         */
        if (linestatus & UART_17158_RX_FIFO_DATA_ERROR)
                jsm_dbg(INTR, &ch->ch_bd->pci_dev,
                        "%s:%d Port: %d Got an RX error, need to parse LSR\n",
                        __FILE__, __LINE__, port);

        /*
         * The next 3 tests should *NOT* happen, as the above test
         * should encapsulate all 3... At least, thats what Exar says.
         */

        if (linestatus & UART_LSR_PE) {
                ch->ch_err_parity++;
                jsm_dbg(INTR, &ch->ch_bd->pci_dev, "%s:%d Port: %d. PAR ERR!\n",
                        __FILE__, __LINE__, port);
        }

        if (linestatus & UART_LSR_FE) {
                ch->ch_err_frame++;
                jsm_dbg(INTR, &ch->ch_bd->pci_dev, "%s:%d Port: %d. FRM ERR!\n",
                        __FILE__, __LINE__, port);
        }

        if (linestatus & UART_LSR_BI) {
                ch->ch_err_break++;
                jsm_dbg(INTR, &ch->ch_bd->pci_dev,
                        "%s:%d Port: %d. BRK INTR!\n",
                        __FILE__, __LINE__, port);
        }

        if (linestatus & UART_LSR_OE) {
                /*
                 * Rx Oruns. Exar says that an orun will NOT corrupt
                 * the FIFO. It will just replace the holding register
                 * with this new data byte. So basically just ignore this.
                 * Probably we should eventually have an orun stat in our driver...
                 */
                ch->ch_err_overrun++;
                jsm_dbg(INTR, &ch->ch_bd->pci_dev,
                        "%s:%d Port: %d. Rx Overrun!\n",
                        __FILE__, __LINE__, port);
        }

        if (linestatus & UART_LSR_THRE) {
                spin_lock_irqsave(&ch->ch_lock, lock_flags);
                ch->ch_flags |= (CH_TX_FIFO_EMPTY | CH_TX_FIFO_LWM);
                spin_unlock_irqrestore(&ch->ch_lock, lock_flags);

                /* Transfer data (if any) from Write Queue -> UART. */
                neo_copy_data_from_queue_to_uart(ch);
        }
        else if (linestatus & UART_17158_TX_AND_FIFO_CLR) {
                spin_lock_irqsave(&ch->ch_lock, lock_flags);
                ch->ch_flags |= (CH_TX_FIFO_EMPTY | CH_TX_FIFO_LWM);
                spin_unlock_irqrestore(&ch->ch_lock, lock_flags);

                /* Transfer data (if any) from Write Queue -> UART. */
                neo_copy_data_from_queue_to_uart(ch);
        }
}

/*
 * neo_param()
 * Send any/all changes to the line to the UART.
 */
static void neo_param(struct jsm_channel *ch)
{
        u8 lcr = 0;
        u8 uart_lcr, ier;
        u32 baud;
        int quot;
        struct jsm_board *bd;

        bd = ch->ch_bd;
        if (!bd)
                return;

        /*
         * If baud rate is zero, flush queues, and set mval to drop DTR.
         */
        if ((ch->ch_c_cflag & CBAUD) == B0) {
                ch->ch_r_head = ch->ch_r_tail = 0;
                ch->ch_e_head = ch->ch_e_tail = 0;

                neo_flush_uart_write(ch);
                neo_flush_uart_read(ch);

                ch->ch_flags |= (CH_BAUD0);
                ch->ch_mostat &= ~(UART_MCR_RTS | UART_MCR_DTR);
                neo_assert_modem_signals(ch);
                return;

        } else {
                int i;
                unsigned int cflag;
                static struct {
                        unsigned int rate;
                        unsigned int cflag;
                } baud_rates[] = {
                        { 921600, B921600 },
                        { 460800, B460800 },
                        { 230400, B230400 },
                        { 115200, B115200 },
                        {  57600, B57600  },
                        {  38400, B38400  },
                        {  19200, B19200  },
                        {   9600, B9600   },
                        {   4800, B4800   },
                        {   2400, B2400   },
                        {   1200, B1200   },
                        {    600, B600    },
                        {    300, B300    },
                        {    200, B200    },
                        {    150, B150    },
                        {    134, B134    },
                        {    110, B110    },
                        {     75, B75     },
                        {     50, B50     },
                };

                cflag = C_BAUD(ch->uart_port.state->port.tty);
                baud = 9600;
                for (i = 0; i < ARRAY_SIZE(baud_rates); i++) {
                        if (baud_rates[i].cflag == cflag) {
                                baud = baud_rates[i].rate;
                                break;
                        }
                }

                if (ch->ch_flags & CH_BAUD0)
                        ch->ch_flags &= ~(CH_BAUD0);
        }

        if (ch->ch_c_cflag & PARENB)
                lcr |= UART_LCR_PARITY;

        if (!(ch->ch_c_cflag & PARODD))
                lcr |= UART_LCR_EPAR;

        if (ch->ch_c_cflag & CMSPAR)
                lcr |= UART_LCR_SPAR;

        if (ch->ch_c_cflag & CSTOPB)
                lcr |= UART_LCR_STOP;

        lcr |= UART_LCR_WLEN(tty_get_char_size(ch->ch_c_cflag));

        ier = readb(&ch->ch_neo_uart->ier);
        uart_lcr = readb(&ch->ch_neo_uart->lcr);

        quot = ch->ch_bd->bd_dividend / baud;

        if (quot != 0) {
                writeb(UART_LCR_DLAB, &ch->ch_neo_uart->lcr);
                writeb((quot & 0xff), &ch->ch_neo_uart->txrx);
                writeb((quot >> 8), &ch->ch_neo_uart->ier);
                writeb(lcr, &ch->ch_neo_uart->lcr);
        }

        if (uart_lcr != lcr)
                writeb(lcr, &ch->ch_neo_uart->lcr);

        if (ch->ch_c_cflag & CREAD)
                ier |= (UART_IER_RDI | UART_IER_RLSI);

        ier |= (UART_IER_THRI | UART_IER_MSI);

        writeb(ier, &ch->ch_neo_uart->ier);

        /* Set new start/stop chars */
        neo_set_new_start_stop_chars(ch);

        if (ch->ch_c_cflag & CRTSCTS)
                neo_set_cts_flow_control(ch);
        else if (ch->ch_c_iflag & IXON) {
                /* If start/stop is set to disable, then we should disable flow control */
                if ((ch->ch_startc == __DISABLED_CHAR) || (ch->ch_stopc == __DISABLED_CHAR))
                        neo_set_no_output_flow_control(ch);
                else
                        neo_set_ixon_flow_control(ch);
        }
        else
                neo_set_no_output_flow_control(ch);

        if (ch->ch_c_cflag & CRTSCTS)
                neo_set_rts_flow_control(ch);
        else if (ch->ch_c_iflag & IXOFF) {
                /* If start/stop is set to disable, then we should disable flow control */
                if ((ch->ch_startc == __DISABLED_CHAR) || (ch->ch_stopc == __DISABLED_CHAR))
                        neo_set_no_input_flow_control(ch);
                else
                        neo_set_ixoff_flow_control(ch);
        }
        else
                neo_set_no_input_flow_control(ch);
        /*
         * Adjust the RX FIFO Trigger level if baud is less than 9600.
         * Not exactly elegant, but this is needed because of the Exar chip's
         * delay on firing off the RX FIFO interrupt on slower baud rates.
         */
        if (baud < 9600) {
                writeb(1, &ch->ch_neo_uart->rfifo);
                ch->ch_r_tlevel = 1;
        }

        neo_assert_modem_signals(ch);

        /* Get current status of the modem signals now */
        neo_parse_modem(ch, readb(&ch->ch_neo_uart->msr));
        return;
}

/*
 * jsm_neo_intr()
 *
 * Neo specific interrupt handler.
 */
static irqreturn_t neo_intr(int irq, void *voidbrd)
{
        struct jsm_board *brd = voidbrd;
        struct jsm_channel *ch;
        int port = 0;
        int type = 0;
        int current_port;
        u32 tmp;
        u32 uart_poll;
        unsigned long lock_flags;
        unsigned long lock_flags2;
        int outofloop_count = 0;

        /* Lock out the slow poller from running on this board. */
        spin_lock_irqsave(&brd->bd_intr_lock, lock_flags);

        /*
         * Read in "extended" IRQ information from the 32bit Neo register.
         * Bits 0-7: What port triggered the interrupt.
         * Bits 8-31: Each 3bits indicate what type of interrupt occurred.
         */
        uart_poll = readl(brd->re_map_membase + UART_17158_POLL_ADDR_OFFSET);

        jsm_dbg(INTR, &brd->pci_dev, "%s:%d uart_poll: %x\n",
                __FILE__, __LINE__, uart_poll);

        if (!uart_poll) {
                jsm_dbg(INTR, &brd->pci_dev,
                        "Kernel interrupted to me, but no pending interrupts...\n");
                spin_unlock_irqrestore(&brd->bd_intr_lock, lock_flags);
                return IRQ_NONE;
        }

        /* At this point, we have at least SOMETHING to service, dig further... */

        current_port = 0;

        /* Loop on each port */
        while (((uart_poll & 0xff) != 0) && (outofloop_count < 0xff)){

                tmp = uart_poll;
                outofloop_count++;

                /* Check current port to see if it has interrupt pending */
                if ((tmp & jsm_offset_table[current_port]) != 0) {
                        port = current_port;
                        type = tmp >> (8 + (port * 3));
                        type &= 0x7;
                } else {
                        current_port++;
                        continue;
                }

                jsm_dbg(INTR, &brd->pci_dev, "%s:%d port: %x type: %x\n",
                        __FILE__, __LINE__, port, type);

                /* Remove this port + type from uart_poll */
                uart_poll &= ~(jsm_offset_table[port]);

                if (!type) {
                        /* If no type, just ignore it, and move onto next port */
                        jsm_dbg(INTR, &brd->pci_dev,
                                "Interrupt with no type! port: %d\n", port);
                        continue;
                }

                /* Switch on type of interrupt we have */
                switch (type) {

                case UART_17158_RXRDY_TIMEOUT:
                        /*
                         * RXRDY Time-out is cleared by reading data in the
                        * RX FIFO until it falls below the trigger level.
                         */

                        /* Verify the port is in range. */
                        if (port >= brd->nasync)
                                continue;

                        ch = brd->channels[port];
                        if (!ch)
                                continue;

                        neo_copy_data_from_uart_to_queue(ch);

                        /* Call our tty layer to enforce queue flow control if needed. */
                        spin_lock_irqsave(&ch->ch_lock, lock_flags2);
                        jsm_check_queue_flow_control(ch);
                        spin_unlock_irqrestore(&ch->ch_lock, lock_flags2);

                        continue;

                case UART_17158_RX_LINE_STATUS:
                        /*
                         * RXRDY and RX LINE Status (logic OR of LSR[4:1])
                         */
                        neo_parse_lsr(brd, port);
                        continue;

                case UART_17158_TXRDY:
                        /*
                         * TXRDY interrupt clears after reading ISR register for the UART channel.
                         */

                        /*
                         * Yes, this is odd...
                         * Why would I check EVERY possibility of type of
                         * interrupt, when we know its TXRDY???
                         * Becuz for some reason, even tho we got triggered for TXRDY,
                         * it seems to be occasionally wrong. Instead of TX, which
                         * it should be, I was getting things like RXDY too. Weird.
                         */
                        neo_parse_isr(brd, port);
                        continue;

                case UART_17158_MSR:
                        /*
                         * MSR or flow control was seen.
                         */
                        neo_parse_isr(brd, port);
                        continue;

                default:
                        /*
                         * The UART triggered us with a bogus interrupt type.
                         * It appears the Exar chip, when REALLY bogged down, will throw
                         * these once and awhile.
                         * Its harmless, just ignore it and move on.
                         */
                        jsm_dbg(INTR, &brd->pci_dev,
                                "%s:%d Unknown Interrupt type: %x\n",
                                __FILE__, __LINE__, type);
                        continue;
                }
        }

        spin_unlock_irqrestore(&brd->bd_intr_lock, lock_flags);

        jsm_dbg(INTR, &brd->pci_dev, "finish\n");
        return IRQ_HANDLED;
}

/*
 * Neo specific way of turning off the receiver.
 * Used as a way to enforce queue flow control when in
 * hardware flow control mode.
 */
static void neo_disable_receiver(struct jsm_channel *ch)
{
        u8 tmp = readb(&ch->ch_neo_uart->ier);
        tmp &= ~(UART_IER_RDI);
        writeb(tmp, &ch->ch_neo_uart->ier);

        /* flush write operation */
        neo_pci_posting_flush(ch->ch_bd);
}


/*
 * Neo specific way of turning on the receiver.
 * Used as a way to un-enforce queue flow control when in
 * hardware flow control mode.
 */
static void neo_enable_receiver(struct jsm_channel *ch)
{
        u8 tmp = readb(&ch->ch_neo_uart->ier);
        tmp |= (UART_IER_RDI);
        writeb(tmp, &ch->ch_neo_uart->ier);

        /* flush write operation */
        neo_pci_posting_flush(ch->ch_bd);
}

static void neo_send_start_character(struct jsm_channel *ch)
{
        if (!ch)
                return;

        if (ch->ch_startc != __DISABLED_CHAR) {
                ch->ch_xon_sends++;
                writeb(ch->ch_startc, &ch->ch_neo_uart->txrx);

                /* flush write operation */
                neo_pci_posting_flush(ch->ch_bd);
        }
}

static void neo_send_stop_character(struct jsm_channel *ch)
{
        if (!ch)
                return;

        if (ch->ch_stopc != __DISABLED_CHAR) {
                ch->ch_xoff_sends++;
                writeb(ch->ch_stopc, &ch->ch_neo_uart->txrx);

                /* flush write operation */
                neo_pci_posting_flush(ch->ch_bd);
        }
}

/*
 * neo_uart_init
 */
static void neo_uart_init(struct jsm_channel *ch)
{
        writeb(0, &ch->ch_neo_uart->ier);
        writeb(0, &ch->ch_neo_uart->efr);
        writeb(UART_EFR_ECB, &ch->ch_neo_uart->efr);

        /* Clear out UART and FIFO */
        readb(&ch->ch_neo_uart->txrx);
        writeb((UART_FCR_ENABLE_FIFO|UART_FCR_CLEAR_RCVR|UART_FCR_CLEAR_XMIT), &ch->ch_neo_uart->isr_fcr);
        readb(&ch->ch_neo_uart->lsr);
        readb(&ch->ch_neo_uart->msr);

        ch->ch_flags |= CH_FIFO_ENABLED;

        /* Assert any signals we want up */
        writeb(ch->ch_mostat, &ch->ch_neo_uart->mcr);
}

/*
 * Make the UART completely turn off.
 */
static void neo_uart_off(struct jsm_channel *ch)
{
        /* Turn off UART enhanced bits */
        writeb(0, &ch->ch_neo_uart->efr);

        /* Stop all interrupts from occurring. */
        writeb(0, &ch->ch_neo_uart->ier);
}

/* Channel lock MUST be held by the calling function! */
static void neo_send_break(struct jsm_channel *ch)
{
        /*
         * Set the time we should stop sending the break.
         * If we are already sending a break, toss away the existing
         * time to stop, and use this new value instead.
         */

        /* Tell the UART to start sending the break */
        if (!(ch->ch_flags & CH_BREAK_SENDING)) {
                u8 temp = readb(&ch->ch_neo_uart->lcr);
                writeb((temp | UART_LCR_SBC), &ch->ch_neo_uart->lcr);
                ch->ch_flags |= (CH_BREAK_SENDING);

                /* flush write operation */
                neo_pci_posting_flush(ch->ch_bd);
        }
}

struct board_ops jsm_neo_ops = {
        .intr                           = neo_intr,
        .uart_init                      = neo_uart_init,
        .uart_off                       = neo_uart_off,
        .param                          = neo_param,
        .assert_modem_signals           = neo_assert_modem_signals,
        .flush_uart_write               = neo_flush_uart_write,
        .flush_uart_read                = neo_flush_uart_read,
        .disable_receiver               = neo_disable_receiver,
        .enable_receiver                = neo_enable_receiver,
        .send_break                     = neo_send_break,
        .clear_break                    = neo_clear_break,
        .send_start_character           = neo_send_start_character,
        .send_stop_character            = neo_send_stop_character,
        .copy_data_from_queue_to_uart   = neo_copy_data_from_queue_to_uart,
};