Merge tag 'trace-printf-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace...

[drm/drm-misc.git] / drivers / tty / serial / pmac_zilog.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Driver for PowerMac Z85c30 based ESCC cell found in the
 * "macio" ASICs of various PowerMac models
 * 
 * Copyright (C) 2003 Ben. Herrenschmidt (benh@kernel.crashing.org)
 *
 * Derived from drivers/macintosh/macserial.c by Paul Mackerras
 * and drivers/serial/sunzilog.c by David S. Miller
 *
 * Hrm... actually, I ripped most of sunzilog (Thanks David !) and
 * adapted special tweaks needed for us. I don't think it's worth
 * merging back those though. The DMA code still has to get in
 * and once done, I expect that driver to remain fairly stable in
 * the long term, unless we change the driver model again...
 *
 * 2004-08-06 Harald Welte <laforge@gnumonks.org>
 *      - Enable BREAK interrupt
 *      - Add support for sysreq
 *
 * TODO:   - Add DMA support
 *         - Defer port shutdown to a few seconds after close
 *         - maybe put something right into uap->clk_divisor
 */

#undef DEBUG
#undef USE_CTRL_O_SYSRQ

#include <linux/module.h>
#include <linux/tty.h>

#include <linux/tty_flip.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/adb.h>
#include <linux/pmu.h>
#include <linux/bitops.h>
#include <linux/sysrq.h>
#include <linux/mutex.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <asm/sections.h>
#include <linux/io.h>
#include <asm/irq.h>

#ifdef CONFIG_PPC_PMAC
#include <asm/machdep.h>
#include <asm/pmac_feature.h>
#include <asm/macio.h>
#else
#include <linux/platform_device.h>
#define of_machine_is_compatible(x) (0)
#endif

#include <linux/serial.h>
#include <linux/serial_core.h>

#include "pmac_zilog.h"

MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
MODULE_DESCRIPTION("Driver for the Mac and PowerMac serial ports.");
MODULE_LICENSE("GPL");

#ifdef CONFIG_SERIAL_PMACZILOG_TTYS
#define PMACZILOG_MAJOR         TTY_MAJOR
#define PMACZILOG_MINOR         64
#define PMACZILOG_NAME          "ttyS"
#else
#define PMACZILOG_MAJOR         204
#define PMACZILOG_MINOR         192
#define PMACZILOG_NAME          "ttyPZ"
#endif

#define pmz_debug(fmt, arg...)  pr_debug("ttyPZ%d: " fmt, uap->port.line, ## arg)
#define pmz_error(fmt, arg...)  pr_err("ttyPZ%d: " fmt, uap->port.line, ## arg)
#define pmz_info(fmt, arg...)   pr_info("ttyPZ%d: " fmt, uap->port.line, ## arg)

/*
 * For the sake of early serial console, we can do a pre-probe
 * (optional) of the ports at rather early boot time.
 */
static struct uart_pmac_port    pmz_ports[MAX_ZS_PORTS];
static int                      pmz_ports_count;

static struct uart_driver pmz_uart_reg = {
        .owner          =       THIS_MODULE,
        .driver_name    =       PMACZILOG_NAME,
        .dev_name       =       PMACZILOG_NAME,
        .major          =       PMACZILOG_MAJOR,
        .minor          =       PMACZILOG_MINOR,
};


/* 
 * Load all registers to reprogram the port
 * This function must only be called when the TX is not busy.  The UART
 * port lock must be held and local interrupts disabled.
 */
static void pmz_load_zsregs(struct uart_pmac_port *uap, u8 *regs)
{
        int i;

        /* Let pending transmits finish.  */
        for (i = 0; i < 1000; i++) {
                unsigned char stat = read_zsreg(uap, R1);
                if (stat & ALL_SNT)
                        break;
                udelay(100);
        }

        ZS_CLEARERR(uap);
        zssync(uap);
        ZS_CLEARFIFO(uap);
        zssync(uap);
        ZS_CLEARERR(uap);

        /* Disable all interrupts.  */
        write_zsreg(uap, R1,
                    regs[R1] & ~(RxINT_MASK | TxINT_ENAB | EXT_INT_ENAB));

        /* Set parity, sync config, stop bits, and clock divisor.  */
        write_zsreg(uap, R4, regs[R4]);

        /* Set misc. TX/RX control bits.  */
        write_zsreg(uap, R10, regs[R10]);

        /* Set TX/RX controls sans the enable bits.  */
        write_zsreg(uap, R3, regs[R3] & ~RxENABLE);
        write_zsreg(uap, R5, regs[R5] & ~TxENABLE);

        /* now set R7 "prime" on ESCC */
        write_zsreg(uap, R15, regs[R15] | EN85C30);
        write_zsreg(uap, R7, regs[R7P]);

        /* make sure we use R7 "non-prime" on ESCC */
        write_zsreg(uap, R15, regs[R15] & ~EN85C30);

        /* Synchronous mode config.  */
        write_zsreg(uap, R6, regs[R6]);
        write_zsreg(uap, R7, regs[R7]);

        /* Disable baud generator.  */
        write_zsreg(uap, R14, regs[R14] & ~BRENAB);

        /* Clock mode control.  */
        write_zsreg(uap, R11, regs[R11]);

        /* Lower and upper byte of baud rate generator divisor.  */
        write_zsreg(uap, R12, regs[R12]);
        write_zsreg(uap, R13, regs[R13]);
        
        /* Now rewrite R14, with BRENAB (if set).  */
        write_zsreg(uap, R14, regs[R14]);

        /* Reset external status interrupts.  */
        write_zsreg(uap, R0, RES_EXT_INT);
        write_zsreg(uap, R0, RES_EXT_INT);

        /* Rewrite R3/R5, this time without enables masked.  */
        write_zsreg(uap, R3, regs[R3]);
        write_zsreg(uap, R5, regs[R5]);

        /* Rewrite R1, this time without IRQ enabled masked.  */
        write_zsreg(uap, R1, regs[R1]);

        /* Enable interrupts */
        write_zsreg(uap, R9, regs[R9]);
}

/* 
 * We do like sunzilog to avoid disrupting pending Tx
 * Reprogram the Zilog channel HW registers with the copies found in the
 * software state struct.  If the transmitter is busy, we defer this update
 * until the next TX complete interrupt.  Else, we do it right now.
 *
 * The UART port lock must be held and local interrupts disabled.
 */
static void pmz_maybe_update_regs(struct uart_pmac_port *uap)
{
        if (!ZS_REGS_HELD(uap)) {
                if (ZS_TX_ACTIVE(uap)) {
                        uap->flags |= PMACZILOG_FLAG_REGS_HELD;
                } else {
                        pmz_debug("pmz: maybe_update_regs: updating\n");
                        pmz_load_zsregs(uap, uap->curregs);
                }
        }
}

static void pmz_interrupt_control(struct uart_pmac_port *uap, int enable)
{
        if (enable) {
                uap->curregs[1] |= INT_ALL_Rx | TxINT_ENAB;
                if (!ZS_IS_EXTCLK(uap))
                        uap->curregs[1] |= EXT_INT_ENAB;
        } else {
                uap->curregs[1] &= ~(EXT_INT_ENAB | TxINT_ENAB | RxINT_MASK);
        }
        write_zsreg(uap, R1, uap->curregs[1]);
}

static bool pmz_receive_chars(struct uart_pmac_port *uap)
        __must_hold(&uap->port.lock)
{
        struct tty_port *port;
        unsigned char ch, r1, drop, flag;

        /* Sanity check, make sure the old bug is no longer happening */
        if (uap->port.state == NULL) {
                WARN_ON(1);
                (void)read_zsdata(uap);
                return false;
        }
        port = &uap->port.state->port;

        while (1) {
                drop = 0;

                r1 = read_zsreg(uap, R1);
                ch = read_zsdata(uap);

                if (r1 & (PAR_ERR | Rx_OVR | CRC_ERR)) {
                        write_zsreg(uap, R0, ERR_RES);
                        zssync(uap);
                }

                ch &= uap->parity_mask;
                if (ch == 0 && uap->flags & PMACZILOG_FLAG_BREAK) {
                        uap->flags &= ~PMACZILOG_FLAG_BREAK;
                }

#if defined(CONFIG_MAGIC_SYSRQ) && defined(CONFIG_SERIAL_CORE_CONSOLE)
#ifdef USE_CTRL_O_SYSRQ
                /* Handle the SysRq ^O Hack */
                if (ch == '\x0f') {
                        uap->port.sysrq = jiffies + HZ*5;
                        goto next_char;
                }
#endif /* USE_CTRL_O_SYSRQ */
                if (uap->port.sysrq) {
                        int swallow;
                        uart_port_unlock(&uap->port);
                        swallow = uart_handle_sysrq_char(&uap->port, ch);
                        uart_port_lock(&uap->port);
                        if (swallow)
                                goto next_char;
                }
#endif /* CONFIG_MAGIC_SYSRQ && CONFIG_SERIAL_CORE_CONSOLE */

                /* A real serial line, record the character and status.  */
                if (drop)
                        goto next_char;

                flag = TTY_NORMAL;
                uap->port.icount.rx++;

                if (r1 & (PAR_ERR | Rx_OVR | CRC_ERR | BRK_ABRT)) {
                        if (r1 & BRK_ABRT) {
                                pmz_debug("pmz: got break !\n");
                                r1 &= ~(PAR_ERR | CRC_ERR);
                                uap->port.icount.brk++;
                                if (uart_handle_break(&uap->port))
                                        goto next_char;
                        }
                        else if (r1 & PAR_ERR)
                                uap->port.icount.parity++;
                        else if (r1 & CRC_ERR)
                                uap->port.icount.frame++;
                        if (r1 & Rx_OVR)
                                uap->port.icount.overrun++;
                        r1 &= uap->port.read_status_mask;
                        if (r1 & BRK_ABRT)
                                flag = TTY_BREAK;
                        else if (r1 & PAR_ERR)
                                flag = TTY_PARITY;
                        else if (r1 & CRC_ERR)
                                flag = TTY_FRAME;
                }

                if (uap->port.ignore_status_mask == 0xff ||
                    (r1 & uap->port.ignore_status_mask) == 0) {
                        tty_insert_flip_char(port, ch, flag);
                }
                if (r1 & Rx_OVR)
                        tty_insert_flip_char(port, 0, TTY_OVERRUN);
        next_char:
                ch = read_zsreg(uap, R0);
                if (!(ch & Rx_CH_AV))
                        break;
        }

        return true;
}

static void pmz_status_handle(struct uart_pmac_port *uap)
{
        unsigned char status;

        status = read_zsreg(uap, R0);
        write_zsreg(uap, R0, RES_EXT_INT);
        zssync(uap);

        if (ZS_IS_OPEN(uap) && ZS_WANTS_MODEM_STATUS(uap)) {
                if (status & SYNC_HUNT)
                        uap->port.icount.dsr++;

                /* The Zilog just gives us an interrupt when DCD/CTS/etc. change.
                 * But it does not tell us which bit has changed, we have to keep
                 * track of this ourselves.
                 * The CTS input is inverted for some reason.  -- paulus
                 */
                if ((status ^ uap->prev_status) & DCD)
                        uart_handle_dcd_change(&uap->port,
                                               (status & DCD));
                if ((status ^ uap->prev_status) & CTS)
                        uart_handle_cts_change(&uap->port,
                                               !(status & CTS));

                wake_up_interruptible(&uap->port.state->port.delta_msr_wait);
        }

        if (status & BRK_ABRT)
                uap->flags |= PMACZILOG_FLAG_BREAK;

        uap->prev_status = status;
}

static void pmz_transmit_chars(struct uart_pmac_port *uap)
{
        struct tty_port *tport;
        unsigned char ch;

        if (ZS_IS_CONS(uap)) {
                unsigned char status = read_zsreg(uap, R0);

                /* TX still busy?  Just wait for the next TX done interrupt.
                 *
                 * It can occur because of how we do serial console writes.  It would
                 * be nice to transmit console writes just like we normally would for
                 * a TTY line. (ie. buffered and TX interrupt driven).  That is not
                 * easy because console writes cannot sleep.  One solution might be
                 * to poll on enough port->xmit space becoming free.  -DaveM
                 */
                if (!(status & Tx_BUF_EMP))
                        return;
        }

        uap->flags &= ~PMACZILOG_FLAG_TX_ACTIVE;

        if (ZS_REGS_HELD(uap)) {
                pmz_load_zsregs(uap, uap->curregs);
                uap->flags &= ~PMACZILOG_FLAG_REGS_HELD;
        }

        if (ZS_TX_STOPPED(uap)) {
                uap->flags &= ~PMACZILOG_FLAG_TX_STOPPED;
                goto ack_tx_int;
        }

        /* Under some circumstances, we see interrupts reported for
         * a closed channel. The interrupt mask in R1 is clear, but
         * R3 still signals the interrupts and we see them when taking
         * an interrupt for the other channel (this could be a qemu
         * bug but since the ESCC doc doesn't specify precsiely whether
         * R3 interrup status bits are masked by R1 interrupt enable
         * bits, better safe than sorry). --BenH.
         */
        if (!ZS_IS_OPEN(uap))
                goto ack_tx_int;

        if (uap->port.x_char) {
                uap->flags |= PMACZILOG_FLAG_TX_ACTIVE;
                write_zsdata(uap, uap->port.x_char);
                zssync(uap);
                uap->port.icount.tx++;
                uap->port.x_char = 0;
                return;
        }

        if (uap->port.state == NULL)
                goto ack_tx_int;
        tport = &uap->port.state->port;
        if (kfifo_is_empty(&tport->xmit_fifo)) {
                uart_write_wakeup(&uap->port);
                goto ack_tx_int;
        }
        if (uart_tx_stopped(&uap->port))
                goto ack_tx_int;

        uap->flags |= PMACZILOG_FLAG_TX_ACTIVE;
        WARN_ON(!uart_fifo_get(&uap->port, &ch));
        write_zsdata(uap, ch);
        zssync(uap);

        if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
                uart_write_wakeup(&uap->port);

        return;

ack_tx_int:
        write_zsreg(uap, R0, RES_Tx_P);
        zssync(uap);
}

/* Hrm... we register that twice, fixme later.... */
static irqreturn_t pmz_interrupt(int irq, void *dev_id)
{
        struct uart_pmac_port *uap = dev_id;
        struct uart_pmac_port *uap_a;
        struct uart_pmac_port *uap_b;
        int rc = IRQ_NONE;
        bool push;
        u8 r3;

        uap_a = pmz_get_port_A(uap);
        uap_b = uap_a->mate;

        uart_port_lock(&uap_a->port);
        r3 = read_zsreg(uap_a, R3);

        /* Channel A */
        push = false;
        if (r3 & (CHAEXT | CHATxIP | CHARxIP)) {
                if (!ZS_IS_OPEN(uap_a)) {
                        pmz_debug("ChanA interrupt while not open !\n");
                        goto skip_a;
                }
                write_zsreg(uap_a, R0, RES_H_IUS);
                zssync(uap_a);          
                if (r3 & CHAEXT)
                        pmz_status_handle(uap_a);
                if (r3 & CHARxIP)
                        push = pmz_receive_chars(uap_a);
                if (r3 & CHATxIP)
                        pmz_transmit_chars(uap_a);
                rc = IRQ_HANDLED;
        }
 skip_a:
        uart_port_unlock(&uap_a->port);
        if (push)
                tty_flip_buffer_push(&uap->port.state->port);

        if (!uap_b)
                goto out;

        uart_port_lock(&uap_b->port);
        push = false;
        if (r3 & (CHBEXT | CHBTxIP | CHBRxIP)) {
                if (!ZS_IS_OPEN(uap_b)) {
                        pmz_debug("ChanB interrupt while not open !\n");
                        goto skip_b;
                }
                write_zsreg(uap_b, R0, RES_H_IUS);
                zssync(uap_b);
                if (r3 & CHBEXT)
                        pmz_status_handle(uap_b);
                if (r3 & CHBRxIP)
                        push = pmz_receive_chars(uap_b);
                if (r3 & CHBTxIP)
                        pmz_transmit_chars(uap_b);
                rc = IRQ_HANDLED;
        }
 skip_b:
        uart_port_unlock(&uap_b->port);
        if (push)
                tty_flip_buffer_push(&uap->port.state->port);

 out:
        return rc;
}

/*
 * Peek the status register, lock not held by caller
 */
static inline u8 pmz_peek_status(struct uart_pmac_port *uap)
{
        unsigned long flags;
        u8 status;
        
        uart_port_lock_irqsave(&uap->port, &flags);
        status = read_zsreg(uap, R0);
        uart_port_unlock_irqrestore(&uap->port, flags);

        return status;
}

/* 
 * Check if transmitter is empty
 * The port lock is not held.
 */
static unsigned int pmz_tx_empty(struct uart_port *port)
{
        unsigned char status;

        status = pmz_peek_status(to_pmz(port));
        if (status & Tx_BUF_EMP)
                return TIOCSER_TEMT;
        return 0;
}

/* 
 * Set Modem Control (RTS & DTR) bits
 * The port lock is held and interrupts are disabled.
 * Note: Shall we really filter out RTS on external ports or
 * should that be dealt at higher level only ?
 */
static void pmz_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
        struct uart_pmac_port *uap = to_pmz(port);
        unsigned char set_bits, clear_bits;

        /* Do nothing for irda for now... */
        if (ZS_IS_IRDA(uap))
                return;
        /* We get called during boot with a port not up yet */
        if (!(ZS_IS_OPEN(uap) || ZS_IS_CONS(uap)))
                return;

        set_bits = clear_bits = 0;

        if (ZS_IS_INTMODEM(uap)) {
                if (mctrl & TIOCM_RTS)
                        set_bits |= RTS;
                else
                        clear_bits |= RTS;
        }
        if (mctrl & TIOCM_DTR)
                set_bits |= DTR;
        else
                clear_bits |= DTR;

        /* NOTE: Not subject to 'transmitter active' rule.  */ 
        uap->curregs[R5] |= set_bits;
        uap->curregs[R5] &= ~clear_bits;

        write_zsreg(uap, R5, uap->curregs[R5]);
        pmz_debug("pmz_set_mctrl: set bits: %x, clear bits: %x -> %x\n",
                  set_bits, clear_bits, uap->curregs[R5]);
        zssync(uap);
}

/* 
 * Get Modem Control bits (only the input ones, the core will
 * or that with a cached value of the control ones)
 * The port lock is held and interrupts are disabled.
 */
static unsigned int pmz_get_mctrl(struct uart_port *port)
{
        struct uart_pmac_port *uap = to_pmz(port);
        unsigned char status;
        unsigned int ret;

        status = read_zsreg(uap, R0);

        ret = 0;
        if (status & DCD)
                ret |= TIOCM_CAR;
        if (status & SYNC_HUNT)
                ret |= TIOCM_DSR;
        if (!(status & CTS))
                ret |= TIOCM_CTS;

        return ret;
}

/* 
 * Stop TX side. Dealt like sunzilog at next Tx interrupt,
 * though for DMA, we will have to do a bit more.
 * The port lock is held and interrupts are disabled.
 */
static void pmz_stop_tx(struct uart_port *port)
{
        to_pmz(port)->flags |= PMACZILOG_FLAG_TX_STOPPED;
}

/* 
 * Kick the Tx side.
 * The port lock is held and interrupts are disabled.
 */
static void pmz_start_tx(struct uart_port *port)
{
        struct uart_pmac_port *uap = to_pmz(port);
        unsigned char status;

        uap->flags |= PMACZILOG_FLAG_TX_ACTIVE;
        uap->flags &= ~PMACZILOG_FLAG_TX_STOPPED;

        status = read_zsreg(uap, R0);

        /* TX busy?  Just wait for the TX done interrupt.  */
        if (!(status & Tx_BUF_EMP))
                return;

        /* Send the first character to jump-start the TX done
         * IRQ sending engine.
         */
        if (port->x_char) {
                write_zsdata(uap, port->x_char);
                zssync(uap);
                port->icount.tx++;
                port->x_char = 0;
        } else {
                struct tty_port *tport = &port->state->port;
                unsigned char ch;

                if (!uart_fifo_get(&uap->port, &ch))
                        return;
                write_zsdata(uap, ch);
                zssync(uap);

                if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
                        uart_write_wakeup(&uap->port);
        }
}

/* 
 * Stop Rx side, basically disable emitting of
 * Rx interrupts on the port. We don't disable the rx
 * side of the chip proper though
 * The port lock is held.
 */
static void pmz_stop_rx(struct uart_port *port)
{
        struct uart_pmac_port *uap = to_pmz(port);

        /* Disable all RX interrupts.  */
        uap->curregs[R1] &= ~RxINT_MASK;
        pmz_maybe_update_regs(uap);
}

/* 
 * Enable modem status change interrupts
 * The port lock is held.
 */
static void pmz_enable_ms(struct uart_port *port)
{
        struct uart_pmac_port *uap = to_pmz(port);
        unsigned char new_reg;

        if (ZS_IS_IRDA(uap))
                return;
        new_reg = uap->curregs[R15] | (DCDIE | SYNCIE | CTSIE);
        if (new_reg != uap->curregs[R15]) {
                uap->curregs[R15] = new_reg;

                /* NOTE: Not subject to 'transmitter active' rule. */
                write_zsreg(uap, R15, uap->curregs[R15]);
        }
}

/* 
 * Control break state emission
 * The port lock is not held.
 */
static void pmz_break_ctl(struct uart_port *port, int break_state)
{
        struct uart_pmac_port *uap = to_pmz(port);
        unsigned char set_bits, clear_bits, new_reg;
        unsigned long flags;

        set_bits = clear_bits = 0;

        if (break_state)
                set_bits |= SND_BRK;
        else
                clear_bits |= SND_BRK;

        uart_port_lock_irqsave(port, &flags);

        new_reg = (uap->curregs[R5] | set_bits) & ~clear_bits;
        if (new_reg != uap->curregs[R5]) {
                uap->curregs[R5] = new_reg;
                write_zsreg(uap, R5, uap->curregs[R5]);
        }

        uart_port_unlock_irqrestore(port, flags);
}

#ifdef CONFIG_PPC_PMAC

/*
 * Turn power on or off to the SCC and associated stuff
 * (port drivers, modem, IR port, etc.)
 * Returns the number of milliseconds we should wait before
 * trying to use the port.
 */
static int pmz_set_scc_power(struct uart_pmac_port *uap, int state)
{
        int delay = 0;
        int rc;

        if (state) {
                rc = pmac_call_feature(
                        PMAC_FTR_SCC_ENABLE, uap->node, uap->port_type, 1);
                pmz_debug("port power on result: %d\n", rc);
                if (ZS_IS_INTMODEM(uap)) {
                        rc = pmac_call_feature(
                                PMAC_FTR_MODEM_ENABLE, uap->node, 0, 1);
                        delay = 2500;   /* wait for 2.5s before using */
                        pmz_debug("modem power result: %d\n", rc);
                }
        } else {
                /* TODO: Make that depend on a timer, don't power down
                 * immediately
                 */
                if (ZS_IS_INTMODEM(uap)) {
                        rc = pmac_call_feature(
                                PMAC_FTR_MODEM_ENABLE, uap->node, 0, 0);
                        pmz_debug("port power off result: %d\n", rc);
                }
                pmac_call_feature(PMAC_FTR_SCC_ENABLE, uap->node, uap->port_type, 0);
        }
        return delay;
}

#else

static int pmz_set_scc_power(struct uart_pmac_port *uap, int state)
{
        return 0;
}

#endif /* !CONFIG_PPC_PMAC */

/*
 * FixZeroBug....Works around a bug in the SCC receiving channel.
 * Inspired from Darwin code, 15 Sept. 2000  -DanM
 *
 * The following sequence prevents a problem that is seen with O'Hare ASICs
 * (most versions -- also with some Heathrow and Hydra ASICs) where a zero
 * at the input to the receiver becomes 'stuck' and locks up the receiver.
 * This problem can occur as a result of a zero bit at the receiver input
 * coincident with any of the following events:
 *
 *      The SCC is initialized (hardware or software).
 *      A framing error is detected.
 *      The clocking option changes from synchronous or X1 asynchronous
 *              clocking to X16, X32, or X64 asynchronous clocking.
 *      The decoding mode is changed among NRZ, NRZI, FM0, or FM1.
 *
 * This workaround attempts to recover from the lockup condition by placing
 * the SCC in synchronous loopback mode with a fast clock before programming
 * any of the asynchronous modes.
 */
static void pmz_fix_zero_bug_scc(struct uart_pmac_port *uap)
{
        write_zsreg(uap, 9, ZS_IS_CHANNEL_A(uap) ? CHRA : CHRB);
        zssync(uap);
        udelay(10);
        write_zsreg(uap, 9, (ZS_IS_CHANNEL_A(uap) ? CHRA : CHRB) | NV);
        zssync(uap);

        write_zsreg(uap, 4, X1CLK | MONSYNC);
        write_zsreg(uap, 3, Rx8);
        write_zsreg(uap, 5, Tx8 | RTS);
        write_zsreg(uap, 9, NV);        /* Didn't we already do this? */
        write_zsreg(uap, 11, RCBR | TCBR);
        write_zsreg(uap, 12, 0);
        write_zsreg(uap, 13, 0);
        write_zsreg(uap, 14, (LOOPBAK | BRSRC));
        write_zsreg(uap, 14, (LOOPBAK | BRSRC | BRENAB));
        write_zsreg(uap, 3, Rx8 | RxENABLE);
        write_zsreg(uap, 0, RES_EXT_INT);
        write_zsreg(uap, 0, RES_EXT_INT);
        write_zsreg(uap, 0, RES_EXT_INT);       /* to kill some time */

        /* The channel should be OK now, but it is probably receiving
         * loopback garbage.
         * Switch to asynchronous mode, disable the receiver,
         * and discard everything in the receive buffer.
         */
        write_zsreg(uap, 9, NV);
        write_zsreg(uap, 4, X16CLK | SB_MASK);
        write_zsreg(uap, 3, Rx8);

        while (read_zsreg(uap, 0) & Rx_CH_AV) {
                (void)read_zsreg(uap, 8);
                write_zsreg(uap, 0, RES_EXT_INT);
                write_zsreg(uap, 0, ERR_RES);
        }
}

/*
 * Real startup routine, powers up the hardware and sets up
 * the SCC. Returns a delay in ms where you need to wait before
 * actually using the port, this is typically the internal modem
 * powerup delay. This routine expect the lock to be taken.
 */
static int __pmz_startup(struct uart_pmac_port *uap)
{
        int pwr_delay = 0;

        memset(&uap->curregs, 0, sizeof(uap->curregs));

        /* Power up the SCC & underlying hardware (modem/irda) */
        pwr_delay = pmz_set_scc_power(uap, 1);

        /* Nice buggy HW ... */
        pmz_fix_zero_bug_scc(uap);

        /* Reset the channel */
        uap->curregs[R9] = 0;
        write_zsreg(uap, 9, ZS_IS_CHANNEL_A(uap) ? CHRA : CHRB);
        zssync(uap);
        udelay(10);
        write_zsreg(uap, 9, 0);
        zssync(uap);

        /* Clear the interrupt registers */
        write_zsreg(uap, R1, 0);
        write_zsreg(uap, R0, ERR_RES);
        write_zsreg(uap, R0, ERR_RES);
        write_zsreg(uap, R0, RES_H_IUS);
        write_zsreg(uap, R0, RES_H_IUS);

        /* Setup some valid baud rate */
        uap->curregs[R4] = X16CLK | SB1;
        uap->curregs[R3] = Rx8;
        uap->curregs[R5] = Tx8 | RTS;
        if (!ZS_IS_IRDA(uap))
                uap->curregs[R5] |= DTR;
        uap->curregs[R12] = 0;
        uap->curregs[R13] = 0;
        uap->curregs[R14] = BRENAB;

        /* Clear handshaking, enable BREAK interrupts */
        uap->curregs[R15] = BRKIE;

        /* Master interrupt enable */
        uap->curregs[R9] |= NV | MIE;

        pmz_load_zsregs(uap, uap->curregs);

        /* Enable receiver and transmitter.  */
        write_zsreg(uap, R3, uap->curregs[R3] |= RxENABLE);
        write_zsreg(uap, R5, uap->curregs[R5] |= TxENABLE);

        /* Remember status for DCD/CTS changes */
        uap->prev_status = read_zsreg(uap, R0);

        return pwr_delay;
}

static void pmz_irda_reset(struct uart_pmac_port *uap)
{
        unsigned long flags;

        uart_port_lock_irqsave(&uap->port, &flags);
        uap->curregs[R5] |= DTR;
        write_zsreg(uap, R5, uap->curregs[R5]);
        zssync(uap);
        uart_port_unlock_irqrestore(&uap->port, flags);
        msleep(110);

        uart_port_lock_irqsave(&uap->port, &flags);
        uap->curregs[R5] &= ~DTR;
        write_zsreg(uap, R5, uap->curregs[R5]);
        zssync(uap);
        uart_port_unlock_irqrestore(&uap->port, flags);
        msleep(10);
}

/*
 * This is the "normal" startup routine, using the above one
 * wrapped with the lock and doing a schedule delay
 */
static int pmz_startup(struct uart_port *port)
{
        struct uart_pmac_port *uap = to_pmz(port);
        unsigned long flags;
        int pwr_delay = 0;

        uap->flags |= PMACZILOG_FLAG_IS_OPEN;

        /* A console is never powered down. Else, power up and
         * initialize the chip
         */
        if (!ZS_IS_CONS(uap)) {
                uart_port_lock_irqsave(port, &flags);
                pwr_delay = __pmz_startup(uap);
                uart_port_unlock_irqrestore(port, flags);
        }       
        sprintf(uap->irq_name, PMACZILOG_NAME"%d", uap->port.line);
        if (request_irq(uap->port.irq, pmz_interrupt, IRQF_SHARED,
                        uap->irq_name, uap)) {
                pmz_error("Unable to register zs interrupt handler.\n");
                pmz_set_scc_power(uap, 0);
                return -ENXIO;
        }

        /* Right now, we deal with delay by blocking here, I'll be
         * smarter later on
         */
        if (pwr_delay != 0) {
                pmz_debug("pmz: delaying %d ms\n", pwr_delay);
                msleep(pwr_delay);
        }

        /* IrDA reset is done now */
        if (ZS_IS_IRDA(uap))
                pmz_irda_reset(uap);

        /* Enable interrupt requests for the channel */
        uart_port_lock_irqsave(port, &flags);
        pmz_interrupt_control(uap, 1);
        uart_port_unlock_irqrestore(port, flags);

        return 0;
}

static void pmz_shutdown(struct uart_port *port)
{
        struct uart_pmac_port *uap = to_pmz(port);
        unsigned long flags;

        uart_port_lock_irqsave(port, &flags);

        /* Disable interrupt requests for the channel */
        pmz_interrupt_control(uap, 0);

        if (!ZS_IS_CONS(uap)) {
                /* Disable receiver and transmitter */
                uap->curregs[R3] &= ~RxENABLE;
                uap->curregs[R5] &= ~TxENABLE;

                /* Disable break assertion */
                uap->curregs[R5] &= ~SND_BRK;
                pmz_maybe_update_regs(uap);
        }

        uart_port_unlock_irqrestore(port, flags);

        /* Release interrupt handler */
        free_irq(uap->port.irq, uap);

        uart_port_lock_irqsave(port, &flags);

        uap->flags &= ~PMACZILOG_FLAG_IS_OPEN;

        if (!ZS_IS_CONS(uap))
                pmz_set_scc_power(uap, 0);      /* Shut the chip down */

        uart_port_unlock_irqrestore(port, flags);
}

/* Shared by TTY driver and serial console setup.  The port lock is held
 * and local interrupts are disabled.
 */
static void pmz_convert_to_zs(struct uart_pmac_port *uap, unsigned int cflag,
                              unsigned int iflag, unsigned long baud)
{
        int brg;

        /* Switch to external clocking for IrDA high clock rates. That
         * code could be re-used for Midi interfaces with different
         * multipliers
         */
        if (baud >= 115200 && ZS_IS_IRDA(uap)) {
                uap->curregs[R4] = X1CLK;
                uap->curregs[R11] = RCTRxCP | TCTRxCP;
                uap->curregs[R14] = 0; /* BRG off */
                uap->curregs[R12] = 0;
                uap->curregs[R13] = 0;
                uap->flags |= PMACZILOG_FLAG_IS_EXTCLK;
        } else {
                switch (baud) {
                case ZS_CLOCK/16:       /* 230400 */
                        uap->curregs[R4] = X16CLK;
                        uap->curregs[R11] = 0;
                        uap->curregs[R14] = 0;
                        break;
                case ZS_CLOCK/32:       /* 115200 */
                        uap->curregs[R4] = X32CLK;
                        uap->curregs[R11] = 0;
                        uap->curregs[R14] = 0;
                        break;
                default:
                        uap->curregs[R4] = X16CLK;
                        uap->curregs[R11] = TCBR | RCBR;
                        brg = BPS_TO_BRG(baud, ZS_CLOCK / 16);
                        uap->curregs[R12] = (brg & 255);
                        uap->curregs[R13] = ((brg >> 8) & 255);
                        uap->curregs[R14] = BRENAB;
                }
                uap->flags &= ~PMACZILOG_FLAG_IS_EXTCLK;
        }

        /* Character size, stop bits, and parity. */
        uap->curregs[3] &= ~RxN_MASK;
        uap->curregs[5] &= ~TxN_MASK;

        switch (cflag & CSIZE) {
        case CS5:
                uap->curregs[3] |= Rx5;
                uap->curregs[5] |= Tx5;
                uap->parity_mask = 0x1f;
                break;
        case CS6:
                uap->curregs[3] |= Rx6;
                uap->curregs[5] |= Tx6;
                uap->parity_mask = 0x3f;
                break;
        case CS7:
                uap->curregs[3] |= Rx7;
                uap->curregs[5] |= Tx7;
                uap->parity_mask = 0x7f;
                break;
        case CS8:
        default:
                uap->curregs[3] |= Rx8;
                uap->curregs[5] |= Tx8;
                uap->parity_mask = 0xff;
                break;
        }
        uap->curregs[4] &= ~(SB_MASK);
        if (cflag & CSTOPB)
                uap->curregs[4] |= SB2;
        else
                uap->curregs[4] |= SB1;
        if (cflag & PARENB)
                uap->curregs[4] |= PAR_ENAB;
        else
                uap->curregs[4] &= ~PAR_ENAB;
        if (!(cflag & PARODD))
                uap->curregs[4] |= PAR_EVEN;
        else
                uap->curregs[4] &= ~PAR_EVEN;

        uap->port.read_status_mask = Rx_OVR;
        if (iflag & INPCK)
                uap->port.read_status_mask |= CRC_ERR | PAR_ERR;
        if (iflag & (IGNBRK | BRKINT | PARMRK))
                uap->port.read_status_mask |= BRK_ABRT;

        uap->port.ignore_status_mask = 0;
        if (iflag & IGNPAR)
                uap->port.ignore_status_mask |= CRC_ERR | PAR_ERR;
        if (iflag & IGNBRK) {
                uap->port.ignore_status_mask |= BRK_ABRT;
                if (iflag & IGNPAR)
                        uap->port.ignore_status_mask |= Rx_OVR;
        }

        if ((cflag & CREAD) == 0)
                uap->port.ignore_status_mask = 0xff;
}


/*
 * Set the irda codec on the imac to the specified baud rate.
 */
static void pmz_irda_setup(struct uart_pmac_port *uap, unsigned long *baud)
{
        u8 cmdbyte;
        int t, version;

        switch (*baud) {
        /* SIR modes */
        case 2400:
                cmdbyte = 0x53;
                break;
        case 4800:
                cmdbyte = 0x52;
                break;
        case 9600:
                cmdbyte = 0x51;
                break;
        case 19200:
                cmdbyte = 0x50;
                break;
        case 38400:
                cmdbyte = 0x4f;
                break;
        case 57600:
                cmdbyte = 0x4e;
                break;
        case 115200:
                cmdbyte = 0x4d;
                break;
        /* The FIR modes aren't really supported at this point, how
         * do we select the speed ? via the FCR on KeyLargo ?
         */
        case 1152000:
                cmdbyte = 0;
                break;
        case 4000000:
                cmdbyte = 0;
                break;
        default: /* 9600 */
                cmdbyte = 0x51;
                *baud = 9600;
                break;
        }

        /* Wait for transmitter to drain */
        t = 10000;
        while ((read_zsreg(uap, R0) & Tx_BUF_EMP) == 0
               || (read_zsreg(uap, R1) & ALL_SNT) == 0) {
                if (--t <= 0) {
                        pmz_error("transmitter didn't drain\n");
                        return;
                }
                udelay(10);
        }

        /* Drain the receiver too */
        t = 100;
        (void)read_zsdata(uap);
        (void)read_zsdata(uap);
        (void)read_zsdata(uap);
        mdelay(10);
        while (read_zsreg(uap, R0) & Rx_CH_AV) {
                read_zsdata(uap);
                mdelay(10);
                if (--t <= 0) {
                        pmz_error("receiver didn't drain\n");
                        return;
                }
        }

        /* Switch to command mode */
        uap->curregs[R5] |= DTR;
        write_zsreg(uap, R5, uap->curregs[R5]);
        zssync(uap);
        mdelay(1);

        /* Switch SCC to 19200 */
        pmz_convert_to_zs(uap, CS8, 0, 19200);          
        pmz_load_zsregs(uap, uap->curregs);
        mdelay(1);

        /* Write get_version command byte */
        write_zsdata(uap, 1);
        t = 5000;
        while ((read_zsreg(uap, R0) & Rx_CH_AV) == 0) {
                if (--t <= 0) {
                        pmz_error("irda_setup timed out on get_version byte\n");
                        goto out;
                }
                udelay(10);
        }
        version = read_zsdata(uap);

        if (version < 4) {
                pmz_info("IrDA: dongle version %d not supported\n", version);
                goto out;
        }

        /* Send speed mode */
        write_zsdata(uap, cmdbyte);
        t = 5000;
        while ((read_zsreg(uap, R0) & Rx_CH_AV) == 0) {
                if (--t <= 0) {
                        pmz_error("irda_setup timed out on speed mode byte\n");
                        goto out;
                }
                udelay(10);
        }
        t = read_zsdata(uap);
        if (t != cmdbyte)
                pmz_error("irda_setup speed mode byte = %x (%x)\n", t, cmdbyte);

        pmz_info("IrDA setup for %ld bps, dongle version: %d\n",
                 *baud, version);

        (void)read_zsdata(uap);
        (void)read_zsdata(uap);
        (void)read_zsdata(uap);

 out:
        /* Switch back to data mode */
        uap->curregs[R5] &= ~DTR;
        write_zsreg(uap, R5, uap->curregs[R5]);
        zssync(uap);

        (void)read_zsdata(uap);
        (void)read_zsdata(uap);
        (void)read_zsdata(uap);
}


static void __pmz_set_termios(struct uart_port *port, struct ktermios *termios,
                              const struct ktermios *old)
{
        struct uart_pmac_port *uap = to_pmz(port);
        unsigned long baud;

        /* XXX Check which revs of machines actually allow 1 and 4Mb speeds
         * on the IR dongle. Note that the IRTTY driver currently doesn't know
         * about the FIR mode and high speed modes. So these are unused. For
         * implementing proper support for these, we should probably add some
         * DMA as well, at least on the Rx side, which isn't a simple thing
         * at this point.
         */
        if (ZS_IS_IRDA(uap)) {
                /* Calc baud rate */
                baud = uart_get_baud_rate(port, termios, old, 1200, 4000000);
                pmz_debug("pmz: switch IRDA to %ld bauds\n", baud);
                /* Cet the irda codec to the right rate */
                pmz_irda_setup(uap, &baud);
                /* Set final baud rate */
                pmz_convert_to_zs(uap, termios->c_cflag, termios->c_iflag, baud);
                pmz_load_zsregs(uap, uap->curregs);
                zssync(uap);
        } else {
                baud = uart_get_baud_rate(port, termios, old, 1200, 230400);
                pmz_convert_to_zs(uap, termios->c_cflag, termios->c_iflag, baud);
                /* Make sure modem status interrupts are correctly configured */
                if (UART_ENABLE_MS(&uap->port, termios->c_cflag)) {
                        uap->curregs[R15] |= DCDIE | SYNCIE | CTSIE;
                        uap->flags |= PMACZILOG_FLAG_MODEM_STATUS;
                } else {
                        uap->curregs[R15] &= ~(DCDIE | SYNCIE | CTSIE);
                        uap->flags &= ~PMACZILOG_FLAG_MODEM_STATUS;
                }

                /* Load registers to the chip */
                pmz_maybe_update_regs(uap);
        }
        uart_update_timeout(port, termios->c_cflag, baud);
}

/* The port lock is not held.  */
static void pmz_set_termios(struct uart_port *port, struct ktermios *termios,
                            const struct ktermios *old)
{
        struct uart_pmac_port *uap = to_pmz(port);
        unsigned long flags;

        uart_port_lock_irqsave(port, &flags);   

        /* Disable IRQs on the port */
        pmz_interrupt_control(uap, 0);

        /* Setup new port configuration */
        __pmz_set_termios(port, termios, old);

        /* Re-enable IRQs on the port */
        if (ZS_IS_OPEN(uap))
                pmz_interrupt_control(uap, 1);

        uart_port_unlock_irqrestore(port, flags);
}

static const char *pmz_type(struct uart_port *port)
{
        struct uart_pmac_port *uap = to_pmz(port);

        if (ZS_IS_IRDA(uap))
                return "Z85c30 ESCC - Infrared port";
        else if (ZS_IS_INTMODEM(uap))
                return "Z85c30 ESCC - Internal modem";
        return "Z85c30 ESCC - Serial port";
}

/* We do not request/release mappings of the registers here, this
 * happens at early serial probe time.
 */
static void pmz_release_port(struct uart_port *port)
{
}

static int pmz_request_port(struct uart_port *port)
{
        return 0;
}

/* These do not need to do anything interesting either.  */
static void pmz_config_port(struct uart_port *port, int flags)
{
}

/* We do not support letting the user mess with the divisor, IRQ, etc. */
static int pmz_verify_port(struct uart_port *port, struct serial_struct *ser)
{
        return -EINVAL;
}

#ifdef CONFIG_CONSOLE_POLL

static int pmz_poll_get_char(struct uart_port *port)
{
        struct uart_pmac_port *uap =
                container_of(port, struct uart_pmac_port, port);
        int tries = 2;

        while (tries) {
                if ((read_zsreg(uap, R0) & Rx_CH_AV) != 0)
                        return read_zsdata(uap);
                if (tries--)
                        udelay(5);
        }

        return NO_POLL_CHAR;
}

static void pmz_poll_put_char(struct uart_port *port, unsigned char c)
{
        struct uart_pmac_port *uap =
                container_of(port, struct uart_pmac_port, port);

        /* Wait for the transmit buffer to empty. */
        while ((read_zsreg(uap, R0) & Tx_BUF_EMP) == 0)
                udelay(5);
        write_zsdata(uap, c);
}

#endif /* CONFIG_CONSOLE_POLL */

static const struct uart_ops pmz_pops = {
        .tx_empty       =       pmz_tx_empty,
        .set_mctrl      =       pmz_set_mctrl,
        .get_mctrl      =       pmz_get_mctrl,
        .stop_tx        =       pmz_stop_tx,
        .start_tx       =       pmz_start_tx,
        .stop_rx        =       pmz_stop_rx,
        .enable_ms      =       pmz_enable_ms,
        .break_ctl      =       pmz_break_ctl,
        .startup        =       pmz_startup,
        .shutdown       =       pmz_shutdown,
        .set_termios    =       pmz_set_termios,
        .type           =       pmz_type,
        .release_port   =       pmz_release_port,
        .request_port   =       pmz_request_port,
        .config_port    =       pmz_config_port,
        .verify_port    =       pmz_verify_port,
#ifdef CONFIG_CONSOLE_POLL
        .poll_get_char  =       pmz_poll_get_char,
        .poll_put_char  =       pmz_poll_put_char,
#endif
};

#ifdef CONFIG_PPC_PMAC

/*
 * Setup one port structure after probing, HW is down at this point,
 * Unlike sunzilog, we don't need to pre-init the spinlock as we don't
 * register our console before uart_add_one_port() is called
 */
static int __init pmz_init_port(struct uart_pmac_port *uap)
{
        struct device_node *np = uap->node;
        const char *conn;
        const struct slot_names_prop {
                int     count;
                char    name[1];
        } *slots;
        int len;
        struct resource r_ports;

        /*
         * Request & map chip registers
         */
        if (of_address_to_resource(np, 0, &r_ports))
                return -ENODEV;
        uap->port.mapbase = r_ports.start;
        uap->port.membase = ioremap(uap->port.mapbase, 0x1000);

        uap->control_reg = uap->port.membase;
        uap->data_reg = uap->control_reg + 0x10;

        /*
         * Detect port type
         */
        if (of_device_is_compatible(np, "cobalt"))
                uap->flags |= PMACZILOG_FLAG_IS_INTMODEM;
        conn = of_get_property(np, "AAPL,connector", &len);
        if (conn && (strcmp(conn, "infrared") == 0))
                uap->flags |= PMACZILOG_FLAG_IS_IRDA;
        uap->port_type = PMAC_SCC_ASYNC;
        /* 1999 Powerbook G3 has slot-names property instead */
        slots = of_get_property(np, "slot-names", &len);
        if (slots && slots->count > 0) {
                if (strcmp(slots->name, "IrDA") == 0)
                        uap->flags |= PMACZILOG_FLAG_IS_IRDA;
                else if (strcmp(slots->name, "Modem") == 0)
                        uap->flags |= PMACZILOG_FLAG_IS_INTMODEM;
        }
        if (ZS_IS_IRDA(uap))
                uap->port_type = PMAC_SCC_IRDA;
        if (ZS_IS_INTMODEM(uap)) {
                struct device_node* i2c_modem =
                        of_find_node_by_name(NULL, "i2c-modem");
                if (i2c_modem) {
                        const char* mid =
                                of_get_property(i2c_modem, "modem-id", NULL);
                        if (mid) switch(*mid) {
                        case 0x04 :
                        case 0x05 :
                        case 0x07 :
                        case 0x08 :
                        case 0x0b :
                        case 0x0c :
                                uap->port_type = PMAC_SCC_I2S1;
                        }
                        printk(KERN_INFO "pmac_zilog: i2c-modem detected, id: %d\n",
                                mid ? (*mid) : 0);
                        of_node_put(i2c_modem);
                } else {
                        printk(KERN_INFO "pmac_zilog: serial modem detected\n");
                }
        }

        /*
         * Init remaining bits of "port" structure
         */
        uap->port.iotype = UPIO_MEM;
        uap->port.irq = irq_of_parse_and_map(np, 0);
        uap->port.uartclk = ZS_CLOCK;
        uap->port.fifosize = 1;
        uap->port.ops = &pmz_pops;
        uap->port.type = PORT_PMAC_ZILOG;
        uap->port.flags = 0;

        /*
         * Fixup for the port on Gatwick for which the device-tree has
         * missing interrupts. Normally, the macio_dev would contain
         * fixed up interrupt info, but we use the device-tree directly
         * here due to early probing so we need the fixup too.
         */
        if (uap->port.irq == 0 &&
            np->parent && np->parent->parent &&
            of_device_is_compatible(np->parent->parent, "gatwick")) {
                /* IRQs on gatwick are offset by 64 */
                uap->port.irq = irq_create_mapping(NULL, 64 + 15);
        }

        /* Setup some valid baud rate information in the register
         * shadows so we don't write crap there before baud rate is
         * first initialized.
         */
        pmz_convert_to_zs(uap, CS8, 0, 9600);

        return 0;
}

/*
 * Get rid of a port on module removal
 */
static void pmz_dispose_port(struct uart_pmac_port *uap)
{
        struct device_node *np;

        np = uap->node;
        iounmap(uap->control_reg);
        uap->node = NULL;
        of_node_put(np);
        memset(uap, 0, sizeof(struct uart_pmac_port));
}

/*
 * Called upon match with an escc node in the device-tree.
 */
static int pmz_attach(struct macio_dev *mdev, const struct of_device_id *match)
{
        struct uart_pmac_port *uap;
        int i;
        
        /* Iterate the pmz_ports array to find a matching entry
         */
        for (i = 0; i < MAX_ZS_PORTS; i++)
                if (pmz_ports[i].node == mdev->ofdev.dev.of_node)
                        break;
        if (i >= MAX_ZS_PORTS)
                return -ENODEV;


        uap = &pmz_ports[i];
        uap->dev = mdev;
        uap->port.dev = &mdev->ofdev.dev;
        dev_set_drvdata(&mdev->ofdev.dev, uap);

        /* We still activate the port even when failing to request resources
         * to work around bugs in ancient Apple device-trees
         */
        if (macio_request_resources(uap->dev, "pmac_zilog"))
                printk(KERN_WARNING "%pOFn: Failed to request resource"
                       ", port still active\n",
                       uap->node);
        else
                uap->flags |= PMACZILOG_FLAG_RSRC_REQUESTED;

        return uart_add_one_port(&pmz_uart_reg, &uap->port);
}

/*
 * That one should not be called, macio isn't really a hotswap device,
 * we don't expect one of those serial ports to go away...
 */
static void pmz_detach(struct macio_dev *mdev)
{
        struct uart_pmac_port   *uap = dev_get_drvdata(&mdev->ofdev.dev);
        
        if (!uap)
                return;

        uart_remove_one_port(&pmz_uart_reg, &uap->port);

        if (uap->flags & PMACZILOG_FLAG_RSRC_REQUESTED) {
                macio_release_resources(uap->dev);
                uap->flags &= ~PMACZILOG_FLAG_RSRC_REQUESTED;
        }
        dev_set_drvdata(&mdev->ofdev.dev, NULL);
        uap->dev = NULL;
        uap->port.dev = NULL;
}

static int pmz_suspend(struct macio_dev *mdev, pm_message_t pm_state)
{
        struct uart_pmac_port *uap = dev_get_drvdata(&mdev->ofdev.dev);

        if (uap == NULL) {
                printk("HRM... pmz_suspend with NULL uap\n");
                return 0;
        }

        uart_suspend_port(&pmz_uart_reg, &uap->port);

        return 0;
}


static int pmz_resume(struct macio_dev *mdev)
{
        struct uart_pmac_port *uap = dev_get_drvdata(&mdev->ofdev.dev);

        if (uap == NULL)
                return 0;

        uart_resume_port(&pmz_uart_reg, &uap->port);

        return 0;
}

/*
 * Probe all ports in the system and build the ports array, we register
 * with the serial layer later, so we get a proper struct device which
 * allows the tty to attach properly. This is later than it used to be
 * but the tty layer really wants it that way.
 */
static int __init pmz_probe(void)
{
        struct device_node      *node_p, *node_a, *node_b, *np;
        int                     count = 0;
        int                     rc;

        /*
         * Find all escc chips in the system
         */
        for_each_node_by_name(node_p, "escc") {
                /*
                 * First get channel A/B node pointers
                 * 
                 * TODO: Add routines with proper locking to do that...
                 */
                node_a = node_b = NULL;
                for_each_child_of_node(node_p, np) {
                        if (of_node_name_prefix(np, "ch-a"))
                                node_a = of_node_get(np);
                        else if (of_node_name_prefix(np, "ch-b"))
                                node_b = of_node_get(np);
                }
                if (!node_a && !node_b) {
                        of_node_put(node_a);
                        of_node_put(node_b);
                        printk(KERN_ERR "pmac_zilog: missing node %c for escc %pOF\n",
                                (!node_a) ? 'a' : 'b', node_p);
                        continue;
                }

                /*
                 * Fill basic fields in the port structures
                 */
                if (node_b != NULL) {
                        pmz_ports[count].mate           = &pmz_ports[count+1];
                        pmz_ports[count+1].mate         = &pmz_ports[count];
                }
                pmz_ports[count].flags          = PMACZILOG_FLAG_IS_CHANNEL_A;
                pmz_ports[count].node           = node_a;
                pmz_ports[count+1].node         = node_b;
                pmz_ports[count].port.line      = count;
                pmz_ports[count+1].port.line    = count+1;

                /*
                 * Setup the ports for real
                 */
                rc = pmz_init_port(&pmz_ports[count]);
                if (rc == 0 && node_b != NULL)
                        rc = pmz_init_port(&pmz_ports[count+1]);
                if (rc != 0) {
                        of_node_put(node_a);
                        of_node_put(node_b);
                        memset(&pmz_ports[count], 0, sizeof(struct uart_pmac_port));
                        memset(&pmz_ports[count+1], 0, sizeof(struct uart_pmac_port));
                        continue;
                }
                count += 2;
        }
        pmz_ports_count = count;

        return 0;
}

#else

/* On PCI PowerMacs, pmz_probe() does an explicit search of the OpenFirmware
 * tree to obtain the device_nodes needed to start the console before the
 * macio driver. On Macs without OpenFirmware, global platform_devices take
 * the place of those device_nodes.
 */
extern struct platform_device scc_a_pdev, scc_b_pdev;

static int __init pmz_init_port(struct uart_pmac_port *uap)
{
        struct resource *r_ports;
        int irq;

        r_ports = platform_get_resource(uap->pdev, IORESOURCE_MEM, 0);
        if (!r_ports)
                return -ENODEV;

        irq = platform_get_irq(uap->pdev, 0);
        if (irq < 0)
                return irq;

        uap->port.mapbase  = r_ports->start;
        uap->port.membase  = (unsigned char __iomem *) r_ports->start;
        uap->port.iotype   = UPIO_MEM;
        uap->port.irq      = irq;
        uap->port.uartclk  = ZS_CLOCK;
        uap->port.fifosize = 1;
        uap->port.ops      = &pmz_pops;
        uap->port.type     = PORT_PMAC_ZILOG;
        uap->port.flags    = 0;

        uap->control_reg   = uap->port.membase;
        uap->data_reg      = uap->control_reg + 4;
        uap->port_type     = 0;
        uap->port.has_sysrq = IS_ENABLED(CONFIG_SERIAL_PMACZILOG_CONSOLE);

        pmz_convert_to_zs(uap, CS8, 0, 9600);

        return 0;
}

static int __init pmz_probe(void)
{
        int err;

        pmz_ports_count = 0;

        pmz_ports[0].port.line = 0;
        pmz_ports[0].flags     = PMACZILOG_FLAG_IS_CHANNEL_A;
        pmz_ports[0].pdev      = &scc_a_pdev;
        err = pmz_init_port(&pmz_ports[0]);
        if (err)
                return err;
        pmz_ports_count++;

        pmz_ports[0].mate      = &pmz_ports[1];
        pmz_ports[1].mate      = &pmz_ports[0];
        pmz_ports[1].port.line = 1;
        pmz_ports[1].flags     = 0;
        pmz_ports[1].pdev      = &scc_b_pdev;
        err = pmz_init_port(&pmz_ports[1]);
        if (err)
                return err;
        pmz_ports_count++;

        return 0;
}

static void pmz_dispose_port(struct uart_pmac_port *uap)
{
        memset(uap, 0, sizeof(struct uart_pmac_port));
}

static int pmz_attach(struct platform_device *pdev)
{
        struct uart_pmac_port *uap;
        int i;

        /* Iterate the pmz_ports array to find a matching entry */
        for (i = 0; i < pmz_ports_count; i++)
                if (pmz_ports[i].pdev == pdev)
                        break;
        if (i >= pmz_ports_count)
                return -ENODEV;

        uap = &pmz_ports[i];
        uap->port.dev = &pdev->dev;
        platform_set_drvdata(pdev, uap);

        return uart_add_one_port(&pmz_uart_reg, &uap->port);
}

static void pmz_detach(struct platform_device *pdev)
{
        struct uart_pmac_port *uap = platform_get_drvdata(pdev);

        uart_remove_one_port(&pmz_uart_reg, &uap->port);

        uap->port.dev = NULL;
}

#endif /* !CONFIG_PPC_PMAC */

#ifdef CONFIG_SERIAL_PMACZILOG_CONSOLE

static void pmz_console_write(struct console *con, const char *s, unsigned int count);
static int __init pmz_console_setup(struct console *co, char *options);

static struct console pmz_console = {
        .name   =       PMACZILOG_NAME,
        .write  =       pmz_console_write,
        .device =       uart_console_device,
        .setup  =       pmz_console_setup,
        .flags  =       CON_PRINTBUFFER,
        .index  =       -1,
        .data   =       &pmz_uart_reg,
};

#define PMACZILOG_CONSOLE       &pmz_console
#else /* CONFIG_SERIAL_PMACZILOG_CONSOLE */
#define PMACZILOG_CONSOLE       (NULL)
#endif /* CONFIG_SERIAL_PMACZILOG_CONSOLE */

/*
 * Register the driver, console driver and ports with the serial
 * core
 */
static int __init pmz_register(void)
{
        pmz_uart_reg.nr = pmz_ports_count;
        pmz_uart_reg.cons = PMACZILOG_CONSOLE;

        /*
         * Register this driver with the serial core
         */
        return uart_register_driver(&pmz_uart_reg);
}

#ifdef CONFIG_PPC_PMAC

static const struct of_device_id pmz_match[] =
{
        {
        .name           = "ch-a",
        },
        {
        .name           = "ch-b",
        },
        {},
};
MODULE_DEVICE_TABLE (of, pmz_match);

static struct macio_driver pmz_driver = {
        .driver = {
                .name           = "pmac_zilog",
                .owner          = THIS_MODULE,
                .of_match_table = pmz_match,
        },
        .probe          = pmz_attach,
        .remove         = pmz_detach,
        .suspend        = pmz_suspend,
        .resume         = pmz_resume,
};

#else

static struct platform_driver pmz_driver = {
        .probe          = pmz_attach,
        .remove         = pmz_detach,
        .driver         = {
                .name           = "scc",
        },
};

#endif /* !CONFIG_PPC_PMAC */

static int __init init_pmz(void)
{
        int rc, i;

        /* 
         * First, we need to do a direct OF-based probe pass. We
         * do that because we want serial console up before the
         * macio stuffs calls us back, and since that makes it
         * easier to pass the proper number of channels to
         * uart_register_driver()
         */
        if (pmz_ports_count == 0)
                pmz_probe();

        /*
         * Bail early if no port found
         */
        if (pmz_ports_count == 0)
                return -ENODEV;

        /*
         * Now we register with the serial layer
         */
        rc = pmz_register();
        if (rc) {
                printk(KERN_ERR 
                        "pmac_zilog: Error registering serial device, disabling pmac_zilog.\n"
                        "pmac_zilog: Did another serial driver already claim the minors?\n"); 
                /* effectively "pmz_unprobe()" */
                for (i=0; i < pmz_ports_count; i++)
                        pmz_dispose_port(&pmz_ports[i]);
                return rc;
        }

        /*
         * Then we register the macio driver itself
         */
#ifdef CONFIG_PPC_PMAC
        return macio_register_driver(&pmz_driver);
#else
        return platform_driver_register(&pmz_driver);
#endif
}

static void __exit exit_pmz(void)
{
        int i;

#ifdef CONFIG_PPC_PMAC
        /* Get rid of macio-driver (detach from macio) */
        macio_unregister_driver(&pmz_driver);
#else
        platform_driver_unregister(&pmz_driver);
#endif

        for (i = 0; i < pmz_ports_count; i++) {
                struct uart_pmac_port *uport = &pmz_ports[i];
#ifdef CONFIG_PPC_PMAC
                if (uport->node != NULL)
                        pmz_dispose_port(uport);
#else
                if (uport->pdev != NULL)
                        pmz_dispose_port(uport);
#endif
        }
        /* Unregister UART driver */
        uart_unregister_driver(&pmz_uart_reg);
}

#ifdef CONFIG_SERIAL_PMACZILOG_CONSOLE

static void pmz_console_putchar(struct uart_port *port, unsigned char ch)
{
        struct uart_pmac_port *uap =
                container_of(port, struct uart_pmac_port, port);

        /* Wait for the transmit buffer to empty. */
        while ((read_zsreg(uap, R0) & Tx_BUF_EMP) == 0)
                udelay(5);
        write_zsdata(uap, ch);
}

/*
 * Print a string to the serial port trying not to disturb
 * any possible real use of the port...
 */
static void pmz_console_write(struct console *con, const char *s, unsigned int count)
{
        struct uart_pmac_port *uap = &pmz_ports[con->index];
        unsigned long flags;

        uart_port_lock_irqsave(&uap->port, &flags);

        /* Turn of interrupts and enable the transmitter. */
        write_zsreg(uap, R1, uap->curregs[1] & ~TxINT_ENAB);
        write_zsreg(uap, R5, uap->curregs[5] | TxENABLE | RTS | DTR);

        uart_console_write(&uap->port, s, count, pmz_console_putchar);

        /* Restore the values in the registers. */
        write_zsreg(uap, R1, uap->curregs[1]);
        /* Don't disable the transmitter. */

        uart_port_unlock_irqrestore(&uap->port, flags);
}

/*
 * Setup the serial console
 */
static int __init pmz_console_setup(struct console *co, char *options)
{
        struct uart_pmac_port *uap;
        struct uart_port *port;
        int baud = 38400;
        int bits = 8;
        int parity = 'n';
        int flow = 'n';
        unsigned long pwr_delay;

        /*
         * XServe's default to 57600 bps
         */
        if (of_machine_is_compatible("RackMac1,1")
            || of_machine_is_compatible("RackMac1,2")
            || of_machine_is_compatible("MacRISC4"))
                baud = 57600;

        /*
         * Check whether an invalid uart number has been specified, and
         * if so, search for the first available port that does have
         * console support.
         */
        if (co->index >= pmz_ports_count)
                co->index = 0;
        uap = &pmz_ports[co->index];
#ifdef CONFIG_PPC_PMAC
        if (uap->node == NULL)
                return -ENODEV;
#else
        if (uap->pdev == NULL)
                return -ENODEV;
#endif
        port = &uap->port;

        /*
         * Mark port as beeing a console
         */
        uap->flags |= PMACZILOG_FLAG_IS_CONS;

        /*
         * Temporary fix for uart layer who didn't setup the spinlock yet
         */
        spin_lock_init(&port->lock);

        /*
         * Enable the hardware
         */
        pwr_delay = __pmz_startup(uap);
        if (pwr_delay)
                mdelay(pwr_delay);
        
        if (options)
                uart_parse_options(options, &baud, &parity, &bits, &flow);

        return uart_set_options(port, co, baud, parity, bits, flow);
}

static int __init pmz_console_init(void)
{
        /* Probe ports */
        pmz_probe();

        if (pmz_ports_count == 0)
                return -ENODEV;

        /* TODO: Autoprobe console based on OF */
        /* pmz_console.index = i; */
        register_console(&pmz_console);

        return 0;

}
console_initcall(pmz_console_init);
#endif /* CONFIG_SERIAL_PMACZILOG_CONSOLE */

module_init(init_pmz);
module_exit(exit_pmz);