// SPDX-License-Identifier: GPL-2.0
/* sunsab.c: ASYNC Driver for the SIEMENS SAB82532 DUSCC.
 *
 * Copyright (C) 1997  Eddie C. Dost  (ecd@skynet.be)
 * Copyright (C) 2002, 2006  David S. Miller (davem@davemloft.net)
 *
 * Rewrote buffer handling to use CIRC(Circular Buffer) macros.
 *   Maxim Krasnyanskiy <maxk@qualcomm.com>
 *
 * Fixed to use tty_get_baud_rate, and to allow for arbitrary baud
 * rates to be programmed into the UART.  Also eliminated a lot of
 * duplicated code in the console setup.
 *   Theodore Ts'o <tytso@mit.edu>, 2001-Oct-12
 *
 * Ported to new 2.5.x UART layer.
 *   David S. Miller <davem@davemloft.net>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/ptrace.h>
#include <linux/ioport.h>
#include <linux/circ_buf.h>
#include <linux/serial.h>
#include <linux/sysrq.h>
#include <linux/console.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/of_device.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/prom.h>
#include <asm/setup.h>

#if defined(CONFIG_SERIAL_SUNSAB_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

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

#include "sunsab.h"

struct uart_sunsab_port {
        struct uart_port                port;           /* Generic UART port    */
        union sab82532_async_regs       __iomem *regs;  /* Chip registers       */
        unsigned long                   irqflags;       /* IRQ state flags      */
        int                             dsr;            /* Current DSR state    */
        unsigned int                    cec_timeout;    /* Chip poll timeout... */
        unsigned int                    tec_timeout;    /* likewise             */
        unsigned char                   interrupt_mask0;/* ISR0 masking         */
        unsigned char                   interrupt_mask1;/* ISR1 masking         */
        unsigned char                   pvr_dtr_bit;    /* Which PVR bit is DTR */
        unsigned char                   pvr_dsr_bit;    /* Which PVR bit is DSR */
        unsigned int                    gis_shift;
        int                             type;           /* SAB82532 version     */

        /* Setting configuration bits while the transmitter is active
         * can cause garbage characters to get emitted by the chip.
         * Therefore, we cache such writes here and do the real register
         * write the next time the transmitter becomes idle.
         */
        unsigned int                    cached_ebrg;
        unsigned char                   cached_mode;
        unsigned char                   cached_pvr;
        unsigned char                   cached_dafo;
};

/*
 * This assumes you have a 29.4912 MHz clock for your UART.
 */
#define SAB_BASE_BAUD ( 29491200 / 16 )

static char *sab82532_version[16] = {
        "V1.0", "V2.0", "V3.2", "V(0x03)",
        "V(0x04)", "V(0x05)", "V(0x06)", "V(0x07)",
        "V(0x08)", "V(0x09)", "V(0x0a)", "V(0x0b)",
        "V(0x0c)", "V(0x0d)", "V(0x0e)", "V(0x0f)"
};

#define SAB82532_MAX_TEC_TIMEOUT 200000 /* 1 character time (at 50 baud) */
#define SAB82532_MAX_CEC_TIMEOUT  50000 /* 2.5 TX CLKs (at 50 baud) */

#define SAB82532_RECV_FIFO_SIZE 32      /* Standard async fifo sizes */
#define SAB82532_XMIT_FIFO_SIZE 32

static __inline__ void sunsab_tec_wait(struct uart_sunsab_port *up)
{
        int timeout = up->tec_timeout;

        while ((readb(&up->regs->r.star) & SAB82532_STAR_TEC) && --timeout)
                udelay(1);
}

static __inline__ void sunsab_cec_wait(struct uart_sunsab_port *up)
{
        int timeout = up->cec_timeout;

        while ((readb(&up->regs->r.star) & SAB82532_STAR_CEC) && --timeout)
                udelay(1);
}

static struct tty_port *
receive_chars(struct uart_sunsab_port *up,
              union sab82532_irq_status *stat)
{
        struct tty_port *port = NULL;
        unsigned char buf[32];
        int saw_console_brk = 0;
        int free_fifo = 0;
        int count = 0;
        int i;

        if (up->port.state != NULL)             /* Unopened serial console */
                port = &up->port.state->port;

        /* Read number of BYTES (Character + Status) available. */
        if (stat->sreg.isr0 & SAB82532_ISR0_RPF) {
                count = SAB82532_RECV_FIFO_SIZE;
                free_fifo++;
        }

        if (stat->sreg.isr0 & SAB82532_ISR0_TCD) {
                count = readb(&up->regs->r.rbcl) & (SAB82532_RECV_FIFO_SIZE - 1);
                free_fifo++;
        }

        /* Issue a FIFO read command in case we where idle. */
        if (stat->sreg.isr0 & SAB82532_ISR0_TIME) {
                sunsab_cec_wait(up);
                writeb(SAB82532_CMDR_RFRD, &up->regs->w.cmdr);
                return port;
        }

        if (stat->sreg.isr0 & SAB82532_ISR0_RFO)
                free_fifo++;

        /* Read the FIFO. */
        for (i = 0; i < count; i++)
                buf[i] = readb(&up->regs->r.rfifo[i]);

        /* Issue Receive Message Complete command. */
        if (free_fifo) {
                sunsab_cec_wait(up);
                writeb(SAB82532_CMDR_RMC, &up->regs->w.cmdr);
        }

        /* Count may be zero for BRK, so we check for it here */
        if ((stat->sreg.isr1 & SAB82532_ISR1_BRK) &&
            (up->port.line == up->port.cons->index))
                saw_console_brk = 1;

        if (count == 0) {
                if (unlikely(stat->sreg.isr1 & SAB82532_ISR1_BRK)) {
                        stat->sreg.isr0 &= ~(SAB82532_ISR0_PERR |
                                             SAB82532_ISR0_FERR);
                        up->port.icount.brk++;
                        uart_handle_break(&up->port);
                }
        }

        for (i = 0; i < count; i++) {
                unsigned char ch = buf[i], flag;

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

                if (unlikely(stat->sreg.isr0 & (SAB82532_ISR0_PERR |
                                                SAB82532_ISR0_FERR |
                                                SAB82532_ISR0_RFO)) ||
                    unlikely(stat->sreg.isr1 & SAB82532_ISR1_BRK)) {
                        /*
                         * For statistics only
                         */
                        if (stat->sreg.isr1 & SAB82532_ISR1_BRK) {
                                stat->sreg.isr0 &= ~(SAB82532_ISR0_PERR |
                                                     SAB82532_ISR0_FERR);
                                up->port.icount.brk++;
                                /*
                                 * We do the SysRQ and SAK checking
                                 * here because otherwise the break
                                 * may get masked by ignore_status_mask
                                 * or read_status_mask.
                                 */
                                if (uart_handle_break(&up->port))
                                        continue;
                        } else if (stat->sreg.isr0 & SAB82532_ISR0_PERR)
                                up->port.icount.parity++;
                        else if (stat->sreg.isr0 & SAB82532_ISR0_FERR)
                                up->port.icount.frame++;
                        if (stat->sreg.isr0 & SAB82532_ISR0_RFO)
                                up->port.icount.overrun++;

                        /*
                         * Mask off conditions which should be ingored.
                         */
                        stat->sreg.isr0 &= (up->port.read_status_mask & 0xff);
                        stat->sreg.isr1 &= ((up->port.read_status_mask >> 8) & 0xff);

                        if (stat->sreg.isr1 & SAB82532_ISR1_BRK) {
                                flag = TTY_BREAK;
                        } else if (stat->sreg.isr0 & SAB82532_ISR0_PERR)
                                flag = TTY_PARITY;
                        else if (stat->sreg.isr0 & SAB82532_ISR0_FERR)
                                flag = TTY_FRAME;
                }

                if (uart_handle_sysrq_char(&up->port, ch) || !port)
                        continue;

                if ((stat->sreg.isr0 & (up->port.ignore_status_mask & 0xff)) == 0 &&
                    (stat->sreg.isr1 & ((up->port.ignore_status_mask >> 8) & 0xff)) == 0)
                        tty_insert_flip_char(port, ch, flag);
                if (stat->sreg.isr0 & SAB82532_ISR0_RFO)
                        tty_insert_flip_char(port, 0, TTY_OVERRUN);
        }

        if (saw_console_brk)
                sun_do_break();

        return port;
}

static void sunsab_stop_tx(struct uart_port *);
static void sunsab_tx_idle(struct uart_sunsab_port *);

static void transmit_chars(struct uart_sunsab_port *up,
                           union sab82532_irq_status *stat)
{
        struct circ_buf *xmit = &up->port.state->xmit;
        int i;

        if (stat->sreg.isr1 & SAB82532_ISR1_ALLS) {
                up->interrupt_mask1 |= SAB82532_IMR1_ALLS;
                writeb(up->interrupt_mask1, &up->regs->w.imr1);
                set_bit(SAB82532_ALLS, &up->irqflags);
        }

#if 0 /* bde@nwlink.com says this check causes problems */
        if (!(stat->sreg.isr1 & SAB82532_ISR1_XPR))
                return;
#endif

        if (!(readb(&up->regs->r.star) & SAB82532_STAR_XFW))
                return;

        set_bit(SAB82532_XPR, &up->irqflags);
        sunsab_tx_idle(up);

        if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
                up->interrupt_mask1 |= SAB82532_IMR1_XPR;
                writeb(up->interrupt_mask1, &up->regs->w.imr1);
                return;
        }

        up->interrupt_mask1 &= ~(SAB82532_IMR1_ALLS|SAB82532_IMR1_XPR);
        writeb(up->interrupt_mask1, &up->regs->w.imr1);
        clear_bit(SAB82532_ALLS, &up->irqflags);

        /* Stuff 32 bytes into Transmit FIFO. */
        clear_bit(SAB82532_XPR, &up->irqflags);
        for (i = 0; i < up->port.fifosize; i++) {
                writeb(xmit->buf[xmit->tail],
                       &up->regs->w.xfifo[i]);
                xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
                up->port.icount.tx++;
                if (uart_circ_empty(xmit))
                        break;
        }

        /* Issue a Transmit Frame command. */
        sunsab_cec_wait(up);
        writeb(SAB82532_CMDR_XF, &up->regs->w.cmdr);

        if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
                uart_write_wakeup(&up->port);

        if (uart_circ_empty(xmit))
                sunsab_stop_tx(&up->port);
}

static void check_status(struct uart_sunsab_port *up,
                         union sab82532_irq_status *stat)
{
        if (stat->sreg.isr0 & SAB82532_ISR0_CDSC)
                uart_handle_dcd_change(&up->port,
                                       !(readb(&up->regs->r.vstr) & SAB82532_VSTR_CD));

        if (stat->sreg.isr1 & SAB82532_ISR1_CSC)
                uart_handle_cts_change(&up->port,
                                       (readb(&up->regs->r.star) & SAB82532_STAR_CTS));

        if ((readb(&up->regs->r.pvr) & up->pvr_dsr_bit) ^ up->dsr) {
                up->dsr = (readb(&up->regs->r.pvr) & up->pvr_dsr_bit) ? 0 : 1;
                up->port.icount.dsr++;
        }

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

static irqreturn_t sunsab_interrupt(int irq, void *dev_id)
{
        struct uart_sunsab_port *up = dev_id;
        struct tty_port *port = NULL;
        union sab82532_irq_status status;
        unsigned long flags;
        unsigned char gis;

        spin_lock_irqsave(&up->port.lock, flags);

        status.stat = 0;
        gis = readb(&up->regs->r.gis) >> up->gis_shift;
        if (gis & 1)
                status.sreg.isr0 = readb(&up->regs->r.isr0);
        if (gis & 2)
                status.sreg.isr1 = readb(&up->regs->r.isr1);

        if (status.stat) {
                if ((status.sreg.isr0 & (SAB82532_ISR0_TCD | SAB82532_ISR0_TIME |
                                         SAB82532_ISR0_RFO | SAB82532_ISR0_RPF)) ||
                    (status.sreg.isr1 & SAB82532_ISR1_BRK))
                        port = receive_chars(up, &status);
                if ((status.sreg.isr0 & SAB82532_ISR0_CDSC) ||
                    (status.sreg.isr1 & SAB82532_ISR1_CSC))
                        check_status(up, &status);
                if (status.sreg.isr1 & (SAB82532_ISR1_ALLS | SAB82532_ISR1_XPR))
                        transmit_chars(up, &status);
        }

        spin_unlock_irqrestore(&up->port.lock, flags);

        if (port)
                tty_flip_buffer_push(port);

        return IRQ_HANDLED;
}

/* port->lock is not held.  */
static unsigned int sunsab_tx_empty(struct uart_port *port)
{
        struct uart_sunsab_port *up =
                container_of(port, struct uart_sunsab_port, port);
        int ret;

        /* Do not need a lock for a state test like this.  */
        if (test_bit(SAB82532_ALLS, &up->irqflags))
                ret = TIOCSER_TEMT;
        else
                ret = 0;

        return ret;
}

/* port->lock held by caller.  */
static void sunsab_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
        struct uart_sunsab_port *up =
                container_of(port, struct uart_sunsab_port, port);

        if (mctrl & TIOCM_RTS) {
                up->cached_mode &= ~SAB82532_MODE_FRTS;
                up->cached_mode |= SAB82532_MODE_RTS;
        } else {
                up->cached_mode |= (SAB82532_MODE_FRTS |
                                    SAB82532_MODE_RTS);
        }
        if (mctrl & TIOCM_DTR) {
                up->cached_pvr &= ~(up->pvr_dtr_bit);
        } else {
                up->cached_pvr |= up->pvr_dtr_bit;
        }

        set_bit(SAB82532_REGS_PENDING, &up->irqflags);
        if (test_bit(SAB82532_XPR, &up->irqflags))
                sunsab_tx_idle(up);
}

/* port->lock is held by caller and interrupts are disabled.  */
static unsigned int sunsab_get_mctrl(struct uart_port *port)
{
        struct uart_sunsab_port *up =
                container_of(port, struct uart_sunsab_port, port);
        unsigned char val;
        unsigned int result;

        result = 0;

        val = readb(&up->regs->r.pvr);
        result |= (val & up->pvr_dsr_bit) ? 0 : TIOCM_DSR;

        val = readb(&up->regs->r.vstr);
        result |= (val & SAB82532_VSTR_CD) ? 0 : TIOCM_CAR;

        val = readb(&up->regs->r.star);
        result |= (val & SAB82532_STAR_CTS) ? TIOCM_CTS : 0;

        return result;
}

/* port->lock held by caller.  */
static void sunsab_stop_tx(struct uart_port *port)
{
        struct uart_sunsab_port *up =
                container_of(port, struct uart_sunsab_port, port);

        up->interrupt_mask1 |= SAB82532_IMR1_XPR;
        writeb(up->interrupt_mask1, &up->regs->w.imr1);
}

/* port->lock held by caller.  */
static void sunsab_tx_idle(struct uart_sunsab_port *up)
{
        if (test_bit(SAB82532_REGS_PENDING, &up->irqflags)) {
                u8 tmp;

                clear_bit(SAB82532_REGS_PENDING, &up->irqflags);
                writeb(up->cached_mode, &up->regs->rw.mode);
                writeb(up->cached_pvr, &up->regs->rw.pvr);
                writeb(up->cached_dafo, &up->regs->w.dafo);

                writeb(up->cached_ebrg & 0xff, &up->regs->w.bgr);
                tmp = readb(&up->regs->rw.ccr2);
                tmp &= ~0xc0;
                tmp |= (up->cached_ebrg >> 2) & 0xc0;
                writeb(tmp, &up->regs->rw.ccr2);
        }
}

/* port->lock held by caller.  */
static void sunsab_start_tx(struct uart_port *port)
{
        struct uart_sunsab_port *up =
                container_of(port, struct uart_sunsab_port, port);
        struct circ_buf *xmit = &up->port.state->xmit;
        int i;

        if (uart_circ_empty(xmit) || uart_tx_stopped(port))
                return;

        up->interrupt_mask1 &= ~(SAB82532_IMR1_ALLS|SAB82532_IMR1_XPR);
        writeb(up->interrupt_mask1, &up->regs->w.imr1);
        
        if (!test_bit(SAB82532_XPR, &up->irqflags))
                return;

        clear_bit(SAB82532_ALLS, &up->irqflags);
        clear_bit(SAB82532_XPR, &up->irqflags);

        for (i = 0; i < up->port.fifosize; i++) {
                writeb(xmit->buf[xmit->tail],
                       &up->regs->w.xfifo[i]);
                xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
                up->port.icount.tx++;
                if (uart_circ_empty(xmit))
                        break;
        }

        /* Issue a Transmit Frame command.  */
        sunsab_cec_wait(up);
        writeb(SAB82532_CMDR_XF, &up->regs->w.cmdr);
}

/* port->lock is not held.  */
static void sunsab_send_xchar(struct uart_port *port, char ch)
{
        struct uart_sunsab_port *up =
                container_of(port, struct uart_sunsab_port, port);
        unsigned long flags;

        if (ch == __DISABLED_CHAR)
                return;

        spin_lock_irqsave(&up->port.lock, flags);

        sunsab_tec_wait(up);
        writeb(ch, &up->regs->w.tic);

        spin_unlock_irqrestore(&up->port.lock, flags);
}

/* port->lock held by caller.  */
static void sunsab_stop_rx(struct uart_port *port)
{
        struct uart_sunsab_port *up =
                container_of(port, struct uart_sunsab_port, port);

        up->interrupt_mask0 |= SAB82532_IMR0_TCD;
        writeb(up->interrupt_mask1, &up->regs->w.imr0);
}

/* port->lock is not held.  */
static void sunsab_break_ctl(struct uart_port *port, int break_state)
{
        struct uart_sunsab_port *up =
                container_of(port, struct uart_sunsab_port, port);
        unsigned long flags;
        unsigned char val;

        spin_lock_irqsave(&up->port.lock, flags);

        val = up->cached_dafo;
        if (break_state)
                val |= SAB82532_DAFO_XBRK;
        else
                val &= ~SAB82532_DAFO_XBRK;
        up->cached_dafo = val;

        set_bit(SAB82532_REGS_PENDING, &up->irqflags);
        if (test_bit(SAB82532_XPR, &up->irqflags))
                sunsab_tx_idle(up);

        spin_unlock_irqrestore(&up->port.lock, flags);
}

/* port->lock is not held.  */
static int sunsab_startup(struct uart_port *port)
{
        struct uart_sunsab_port *up =
                container_of(port, struct uart_sunsab_port, port);
        unsigned long flags;
        unsigned char tmp;
        int err = request_irq(up->port.irq, sunsab_interrupt,
                              IRQF_SHARED, "sab", up);
        if (err)
                return err;

        spin_lock_irqsave(&up->port.lock, flags);

        /*
         * Wait for any commands or immediate characters
         */
        sunsab_cec_wait(up);
        sunsab_tec_wait(up);

        /*
         * Clear the FIFO buffers.
         */
        writeb(SAB82532_CMDR_RRES, &up->regs->w.cmdr);
        sunsab_cec_wait(up);
        writeb(SAB82532_CMDR_XRES, &up->regs->w.cmdr);

        /*
         * Clear the interrupt registers.
         */
        (void) readb(&up->regs->r.isr0);
        (void) readb(&up->regs->r.isr1);

        /*
         * Now, initialize the UART 
         */
        writeb(0, &up->regs->w.ccr0);                           /* power-down */
        writeb(SAB82532_CCR0_MCE | SAB82532_CCR0_SC_NRZ |
               SAB82532_CCR0_SM_ASYNC, &up->regs->w.ccr0);
        writeb(SAB82532_CCR1_ODS | SAB82532_CCR1_BCR | 7, &up->regs->w.ccr1);
        writeb(SAB82532_CCR2_BDF | SAB82532_CCR2_SSEL |
               SAB82532_CCR2_TOE, &up->regs->w.ccr2);
        writeb(0, &up->regs->w.ccr3);
        writeb(SAB82532_CCR4_MCK4 | SAB82532_CCR4_EBRG, &up->regs->w.ccr4);
        up->cached_mode = (SAB82532_MODE_RTS | SAB82532_MODE_FCTS |
                           SAB82532_MODE_RAC);
        writeb(up->cached_mode, &up->regs->w.mode);
        writeb(SAB82532_RFC_DPS|SAB82532_RFC_RFTH_32, &up->regs->w.rfc);
        
        tmp = readb(&up->regs->rw.ccr0);
        tmp |= SAB82532_CCR0_PU;        /* power-up */
        writeb(tmp, &up->regs->rw.ccr0);

        /*
         * Finally, enable interrupts
         */
        up->interrupt_mask0 = (SAB82532_IMR0_PERR | SAB82532_IMR0_FERR |
                               SAB82532_IMR0_PLLA);
        writeb(up->interrupt_mask0, &up->regs->w.imr0);
        up->interrupt_mask1 = (SAB82532_IMR1_BRKT | SAB82532_IMR1_ALLS |
                               SAB82532_IMR1_XOFF | SAB82532_IMR1_TIN |
                               SAB82532_IMR1_CSC | SAB82532_IMR1_XON |
                               SAB82532_IMR1_XPR);
        writeb(up->interrupt_mask1, &up->regs->w.imr1);
        set_bit(SAB82532_ALLS, &up->irqflags);
        set_bit(SAB82532_XPR, &up->irqflags);

        spin_unlock_irqrestore(&up->port.lock, flags);

        return 0;
}

/* port->lock is not held.  */
static void sunsab_shutdown(struct uart_port *port)
{
        struct uart_sunsab_port *up =
                container_of(port, struct uart_sunsab_port, port);
        unsigned long flags;

        spin_lock_irqsave(&up->port.lock, flags);

        /* Disable Interrupts */
        up->interrupt_mask0 = 0xff;
        writeb(up->interrupt_mask0, &up->regs->w.imr0);
        up->interrupt_mask1 = 0xff;
        writeb(up->interrupt_mask1, &up->regs->w.imr1);

        /* Disable break condition */
        up->cached_dafo = readb(&up->regs->rw.dafo);
        up->cached_dafo &= ~SAB82532_DAFO_XBRK;
        writeb(up->cached_dafo, &up->regs->rw.dafo);

        /* Disable Receiver */  
        up->cached_mode &= ~SAB82532_MODE_RAC;
        writeb(up->cached_mode, &up->regs->rw.mode);

        /*
         * XXX FIXME
         *
         * If the chip is powered down here the system hangs/crashes during
         * reboot or shutdown.  This needs to be investigated further,
         * similar behaviour occurs in 2.4 when the driver is configured
         * as a module only.  One hint may be that data is sometimes
         * transmitted at 9600 baud during shutdown (regardless of the
         * speed the chip was configured for when the port was open).
         */
#if 0
        /* Power Down */        
        tmp = readb(&up->regs->rw.ccr0);
        tmp &= ~SAB82532_CCR0_PU;
        writeb(tmp, &up->regs->rw.ccr0);
#endif

        spin_unlock_irqrestore(&up->port.lock, flags);
        free_irq(up->port.irq, up);
}

/*
 * This is used to figure out the divisor speeds.
 *
 * The formula is:    Baud = SAB_BASE_BAUD / ((N + 1) * (1 << M)),
 *
 * with               0 <= N < 64 and 0 <= M < 16
 */

static void calc_ebrg(int baud, int *n_ret, int *m_ret)
{
        int     n, m;

        if (baud == 0) {
                *n_ret = 0;
                *m_ret = 0;
                return;
        }
     
        /*
         * We scale numbers by 10 so that we get better accuracy
         * without having to use floating point.  Here we increment m
         * until n is within the valid range.
         */
        n = (SAB_BASE_BAUD * 10) / baud;
        m = 0;
        while (n >= 640) {
                n = n / 2;
                m++;
        }
        n = (n+5) / 10;
        /*
         * We try very hard to avoid speeds with M == 0 since they may
         * not work correctly for XTAL frequences above 10 MHz.
         */
        if ((m == 0) && ((n & 1) == 0)) {
                n = n / 2;
                m++;
        }
        *n_ret = n - 1;
        *m_ret = m;
}

/* Internal routine, port->lock is held and local interrupts are disabled.  */
static void sunsab_convert_to_sab(struct uart_sunsab_port *up, unsigned int cflag,
                                  unsigned int iflag, unsigned int baud,
                                  unsigned int quot)
{
        unsigned char dafo;
        int bits, n, m;

        /* Byte size and parity */
        switch (cflag & CSIZE) {
              case CS5: dafo = SAB82532_DAFO_CHL5; bits = 7; break;
              case CS6: dafo = SAB82532_DAFO_CHL6; bits = 8; break;
              case CS7: dafo = SAB82532_DAFO_CHL7; bits = 9; break;
              case CS8: dafo = SAB82532_DAFO_CHL8; bits = 10; break;
              /* Never happens, but GCC is too dumb to figure it out */
              default:  dafo = SAB82532_DAFO_CHL5; bits = 7; break;
        }

        if (cflag & CSTOPB) {
                dafo |= SAB82532_DAFO_STOP;
                bits++;
        }

        if (cflag & PARENB) {
                dafo |= SAB82532_DAFO_PARE;
                bits++;
        }

        if (cflag & PARODD) {
                dafo |= SAB82532_DAFO_PAR_ODD;
        } else {
                dafo |= SAB82532_DAFO_PAR_EVEN;
        }
        up->cached_dafo = dafo;

        calc_ebrg(baud, &n, &m);

        up->cached_ebrg = n | (m << 6);

        up->tec_timeout = (10 * 1000000) / baud;
        up->cec_timeout = up->tec_timeout >> 2;

        /* CTS flow control flags */
        /* We encode read_status_mask and ignore_status_mask like so:
         *
         * ---------------------
         * | ... | ISR1 | ISR0 |
         * ---------------------
         *  ..    15   8 7    0
         */

        up->port.read_status_mask = (SAB82532_ISR0_TCD | SAB82532_ISR0_TIME |
                                     SAB82532_ISR0_RFO | SAB82532_ISR0_RPF |
                                     SAB82532_ISR0_CDSC);
        up->port.read_status_mask |= (SAB82532_ISR1_CSC |
                                      SAB82532_ISR1_ALLS |
                                      SAB82532_ISR1_XPR) << 8;
        if (iflag & INPCK)
                up->port.read_status_mask |= (SAB82532_ISR0_PERR |
                                              SAB82532_ISR0_FERR);
        if (iflag & (IGNBRK | BRKINT | PARMRK))
                up->port.read_status_mask |= (SAB82532_ISR1_BRK << 8);

        /*
         * Characteres to ignore
         */
        up->port.ignore_status_mask = 0;
        if (iflag & IGNPAR)
                up->port.ignore_status_mask |= (SAB82532_ISR0_PERR |
                                                SAB82532_ISR0_FERR);
        if (iflag & IGNBRK) {
                up->port.ignore_status_mask |= (SAB82532_ISR1_BRK << 8);
                /*
                 * If we're ignoring parity and break indicators,
                 * ignore overruns too (for real raw support).
                 */
                if (iflag & IGNPAR)
                        up->port.ignore_status_mask |= SAB82532_ISR0_RFO;
        }

        /*
         * ignore all characters if CREAD is not set
         */
        if ((cflag & CREAD) == 0)
                up->port.ignore_status_mask |= (SAB82532_ISR0_RPF |
                                                SAB82532_ISR0_TCD);

        uart_update_timeout(&up->port, cflag,
                            (up->port.uartclk / (16 * quot)));

        /* Now schedule a register update when the chip's
         * transmitter is idle.
         */
        up->cached_mode |= SAB82532_MODE_RAC;
        set_bit(SAB82532_REGS_PENDING, &up->irqflags);
        if (test_bit(SAB82532_XPR, &up->irqflags))
                sunsab_tx_idle(up);
}

/* port->lock is not held.  */
static void sunsab_set_termios(struct uart_port *port, struct ktermios *termios,
                               struct ktermios *old)
{
        struct uart_sunsab_port *up =
                container_of(port, struct uart_sunsab_port, port);
        unsigned long flags;
        unsigned int baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
        unsigned int quot = uart_get_divisor(port, baud);

        spin_lock_irqsave(&up->port.lock, flags);
        sunsab_convert_to_sab(up, termios->c_cflag, termios->c_iflag, baud, quot);
        spin_unlock_irqrestore(&up->port.lock, flags);
}

static const char *sunsab_type(struct uart_port *port)
{
        struct uart_sunsab_port *up = (void *)port;
        static char buf[36];
        
        sprintf(buf, "SAB82532 %s", sab82532_version[up->type]);
        return buf;
}

static void sunsab_release_port(struct uart_port *port)
{
}

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

static void sunsab_config_port(struct uart_port *port, int flags)
{
}

static int sunsab_verify_port(struct uart_port *port, struct serial_struct *ser)
{
        return -EINVAL;
}

static const struct uart_ops sunsab_pops = {
        .tx_empty       = sunsab_tx_empty,
        .set_mctrl      = sunsab_set_mctrl,
        .get_mctrl      = sunsab_get_mctrl,
        .stop_tx        = sunsab_stop_tx,
        .start_tx       = sunsab_start_tx,
        .send_xchar     = sunsab_send_xchar,
        .stop_rx        = sunsab_stop_rx,
        .break_ctl      = sunsab_break_ctl,
        .startup        = sunsab_startup,
        .shutdown       = sunsab_shutdown,
        .set_termios    = sunsab_set_termios,
        .type           = sunsab_type,
        .release_port   = sunsab_release_port,
        .request_port   = sunsab_request_port,
        .config_port    = sunsab_config_port,
        .verify_port    = sunsab_verify_port,
};

static struct uart_driver sunsab_reg = {
        .owner                  = THIS_MODULE,
        .driver_name            = "sunsab",
        .dev_name               = "ttyS",
        .major                  = TTY_MAJOR,
};

static struct uart_sunsab_port *sunsab_ports;

#ifdef CONFIG_SERIAL_SUNSAB_CONSOLE

static void sunsab_console_putchar(struct uart_port *port, int c)
{
        struct uart_sunsab_port *up =
                container_of(port, struct uart_sunsab_port, port);

        sunsab_tec_wait(up);
        writeb(c, &up->regs->w.tic);
}

static void sunsab_console_write(struct console *con, const char *s, unsigned n)
{
        struct uart_sunsab_port *up = &sunsab_ports[con->index];
        unsigned long flags;
        int locked = 1;

        if (up->port.sysrq || oops_in_progress)
                locked = spin_trylock_irqsave(&up->port.lock, flags);
        else
                spin_lock_irqsave(&up->port.lock, flags);

        uart_console_write(&up->port, s, n, sunsab_console_putchar);
        sunsab_tec_wait(up);

        if (locked)
                spin_unlock_irqrestore(&up->port.lock, flags);
}

static int sunsab_console_setup(struct console *con, char *options)
{
        struct uart_sunsab_port *up = &sunsab_ports[con->index];
        unsigned long flags;
        unsigned int baud, quot;

        /*
         * The console framework calls us for each and every port
         * registered. Defer the console setup until the requested
         * port has been properly discovered. A bit of a hack,
         * though...
         */
        if (up->port.type != PORT_SUNSAB)
                return -1;

        printk("Console: ttyS%d (SAB82532)\n",
               (sunsab_reg.minor - 64) + con->index);

        sunserial_console_termios(con, up->port.dev->of_node);

        switch (con->cflag & CBAUD) {
        case B150: baud = 150; break;
        case B300: baud = 300; break;
        case B600: baud = 600; break;
        case B1200: baud = 1200; break;
        case B2400: baud = 2400; break;
        case B4800: baud = 4800; break;
        default: case B9600: baud = 9600; break;
        case B19200: baud = 19200; break;
        case B38400: baud = 38400; break;
        case B57600: baud = 57600; break;
        case B115200: baud = 115200; break;
        case B230400: baud = 230400; break;
        case B460800: baud = 460800; break;
        }

        /*
         * Temporary fix.
         */
        spin_lock_init(&up->port.lock);

        /*
         * Initialize the hardware
         */
        sunsab_startup(&up->port);

        spin_lock_irqsave(&up->port.lock, flags);

        /*
         * Finally, enable interrupts
         */
        up->interrupt_mask0 = SAB82532_IMR0_PERR | SAB82532_IMR0_FERR |
                                SAB82532_IMR0_PLLA | SAB82532_IMR0_CDSC;
        writeb(up->interrupt_mask0, &up->regs->w.imr0);
        up->interrupt_mask1 = SAB82532_IMR1_BRKT | SAB82532_IMR1_ALLS |
                                SAB82532_IMR1_XOFF | SAB82532_IMR1_TIN |
                                SAB82532_IMR1_CSC | SAB82532_IMR1_XON |
                                SAB82532_IMR1_XPR;
        writeb(up->interrupt_mask1, &up->regs->w.imr1);

        quot = uart_get_divisor(&up->port, baud);
        sunsab_convert_to_sab(up, con->cflag, 0, baud, quot);
        sunsab_set_mctrl(&up->port, TIOCM_DTR | TIOCM_RTS);

        spin_unlock_irqrestore(&up->port.lock, flags);
        
        return 0;
}

static struct console sunsab_console = {
        .name   =       "ttyS",
        .write  =       sunsab_console_write,
        .device =       uart_console_device,
        .setup  =       sunsab_console_setup,
        .flags  =       CON_PRINTBUFFER,
        .index  =       -1,
        .data   =       &sunsab_reg,
};

static inline struct console *SUNSAB_CONSOLE(void)
{
        return &sunsab_console;
}
#else
#define SUNSAB_CONSOLE()        (NULL)
#define sunsab_console_init()   do { } while (0)
#endif

static int sunsab_init_one(struct uart_sunsab_port *up,
                                     struct platform_device *op,
                                     unsigned long offset,
                                     int line)
{
        up->port.line = line;
        up->port.dev = &op->dev;

        up->port.mapbase = op->resource[0].start + offset;
        up->port.membase = of_ioremap(&op->resource[0], offset,
                                      sizeof(union sab82532_async_regs),
                                      "sab");
        if (!up->port.membase)
                return -ENOMEM;
        up->regs = (union sab82532_async_regs __iomem *) up->port.membase;

        up->port.irq = op->archdata.irqs[0];

        up->port.fifosize = SAB82532_XMIT_FIFO_SIZE;
        up->port.iotype = UPIO_MEM;

        writeb(SAB82532_IPC_IC_ACT_LOW, &up->regs->w.ipc);

        up->port.ops = &sunsab_pops;
        up->port.type = PORT_SUNSAB;
        up->port.uartclk = SAB_BASE_BAUD;

        up->type = readb(&up->regs->r.vstr) & 0x0f;
        writeb(~((1 << 1) | (1 << 2) | (1 << 4)), &up->regs->w.pcr);
        writeb(0xff, &up->regs->w.pim);
        if ((up->port.line & 0x1) == 0) {
                up->pvr_dsr_bit = (1 << 0);
                up->pvr_dtr_bit = (1 << 1);

                up->gis_shift = 2;
        } else {
                up->pvr_dsr_bit = (1 << 3);
                up->pvr_dtr_bit = (1 << 2);
                up->gis_shift = 0;
        }
        up->cached_pvr = (1 << 1) | (1 << 2) | (1 << 4);
        writeb(up->cached_pvr, &up->regs->w.pvr);
        up->cached_mode = readb(&up->regs->rw.mode);
        up->cached_mode |= SAB82532_MODE_FRTS;
        writeb(up->cached_mode, &up->regs->rw.mode);
        up->cached_mode |= SAB82532_MODE_RTS;
        writeb(up->cached_mode, &up->regs->rw.mode);

        up->tec_timeout = SAB82532_MAX_TEC_TIMEOUT;
        up->cec_timeout = SAB82532_MAX_CEC_TIMEOUT;

        return 0;
}

static int sab_probe(struct platform_device *op)
{
        static int inst;
        struct uart_sunsab_port *up;
        int err;

        up = &sunsab_ports[inst * 2];

        err = sunsab_init_one(&up[0], op,
                              0,
                              (inst * 2) + 0);
        if (err)
                goto out;

        err = sunsab_init_one(&up[1], op,
                              sizeof(union sab82532_async_regs),
                              (inst * 2) + 1);
        if (err)
                goto out1;

        sunserial_console_match(SUNSAB_CONSOLE(), op->dev.of_node,
                                &sunsab_reg, up[0].port.line,
                                false);

        sunserial_console_match(SUNSAB_CONSOLE(), op->dev.of_node,
                                &sunsab_reg, up[1].port.line,
                                false);

        err = uart_add_one_port(&sunsab_reg, &up[0].port);
        if (err)
                goto out2;

        err = uart_add_one_port(&sunsab_reg, &up[1].port);
        if (err)
                goto out3;

        platform_set_drvdata(op, &up[0]);

        inst++;

        return 0;

out3:
        uart_remove_one_port(&sunsab_reg, &up[0].port);
out2:
        of_iounmap(&op->resource[0],
                   up[1].port.membase,
                   sizeof(union sab82532_async_regs));
out1:
        of_iounmap(&op->resource[0],
                   up[0].port.membase,
                   sizeof(union sab82532_async_regs));
out:
        return err;
}

static int sab_remove(struct platform_device *op)
{
        struct uart_sunsab_port *up = platform_get_drvdata(op);

        uart_remove_one_port(&sunsab_reg, &up[1].port);
        uart_remove_one_port(&sunsab_reg, &up[0].port);
        of_iounmap(&op->resource[0],
                   up[1].port.membase,
                   sizeof(union sab82532_async_regs));
        of_iounmap(&op->resource[0],
                   up[0].port.membase,
                   sizeof(union sab82532_async_regs));

        return 0;
}

static const struct of_device_id sab_match[] = {
        {
                .name = "se",
        },
        {
                .name = "serial",
                .compatible = "sab82532",
        },
        {},
};
MODULE_DEVICE_TABLE(of, sab_match);

static struct platform_driver sab_driver = {
        .driver = {
                .name = "sab",
                .of_match_table = sab_match,
        },
        .probe          = sab_probe,
        .remove         = sab_remove,
};

static int __init sunsab_init(void)
{
        struct device_node *dp;
        int err;
        int num_channels = 0;

        for_each_node_by_name(dp, "se")
                num_channels += 2;
        for_each_node_by_name(dp, "serial") {
                if (of_device_is_compatible(dp, "sab82532"))
                        num_channels += 2;
        }

        if (num_channels) {
                sunsab_ports = kcalloc(num_channels,
                                       sizeof(struct uart_sunsab_port),
                                       GFP_KERNEL);
                if (!sunsab_ports)
                        return -ENOMEM;

                err = sunserial_register_minors(&sunsab_reg, num_channels);
                if (err) {
                        kfree(sunsab_ports);
                        sunsab_ports = NULL;

                        return err;
                }
        }

        return platform_driver_register(&sab_driver);
}

static void __exit sunsab_exit(void)
{
        platform_driver_unregister(&sab_driver);
        if (sunsab_reg.nr) {
                sunserial_unregister_minors(&sunsab_reg, sunsab_reg.nr);
        }

        kfree(sunsab_ports);
        sunsab_ports = NULL;
}

module_init(sunsab_init);
module_exit(sunsab_exit);

MODULE_AUTHOR("Eddie C. Dost and David S. Miller");
MODULE_DESCRIPTION("Sun SAB82532 serial port driver");
MODULE_LICENSE("GPL");