/*
 * udbg for for NS16550 compatable serial ports
 *
 * Copyright (C) 2001-2005 PPC 64 Team, IBM Corp
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */
#include <linux/types.h>
#include <asm/udbg.h>
#include <asm/io.h>

extern u8 real_readb(volatile u8 __iomem  *addr);
extern void real_writeb(u8 data, volatile u8 __iomem *addr);
extern u8 real_205_readb(volatile u8 __iomem  *addr);
extern void real_205_writeb(u8 data, volatile u8 __iomem *addr);

struct NS16550 {
        /* this struct must be packed */
        unsigned char rbr;  /* 0 */
        unsigned char ier;  /* 1 */
        unsigned char fcr;  /* 2 */
        unsigned char lcr;  /* 3 */
        unsigned char mcr;  /* 4 */
        unsigned char lsr;  /* 5 */
        unsigned char msr;  /* 6 */
        unsigned char scr;  /* 7 */
};

#define thr rbr
#define iir fcr
#define dll rbr
#define dlm ier
#define dlab lcr

#define LSR_DR   0x01  /* Data ready */
#define LSR_OE   0x02  /* Overrun */
#define LSR_PE   0x04  /* Parity error */
#define LSR_FE   0x08  /* Framing error */
#define LSR_BI   0x10  /* Break */
#define LSR_THRE 0x20  /* Xmit holding register empty */
#define LSR_TEMT 0x40  /* Xmitter empty */
#define LSR_ERR  0x80  /* Error */

#define LCR_DLAB 0x80

static volatile struct NS16550 __iomem *udbg_comport;

static void udbg_550_putc(char c)
{
        if (udbg_comport) {
                while ((in_8(&udbg_comport->lsr) & LSR_THRE) == 0)
                        /* wait for idle */;
                out_8(&udbg_comport->thr, c);
                if (c == '\n')
                        udbg_550_putc('\r');
        }
}

static int udbg_550_getc_poll(void)
{
        if (udbg_comport) {
                if ((in_8(&udbg_comport->lsr) & LSR_DR) != 0)
                        return in_8(&udbg_comport->rbr);
                else
                        return -1;
        }
        return -1;
}

static int udbg_550_getc(void)
{
        if (udbg_comport) {
                while ((in_8(&udbg_comport->lsr) & LSR_DR) == 0)
                        /* wait for char */;
                return in_8(&udbg_comport->rbr);
        }
        return -1;
}

void udbg_init_uart(void __iomem *comport, unsigned int speed,
                    unsigned int clock)
{
        unsigned int dll, base_bauds;

        if (clock == 0)
                clock = 1843200;
        if (speed == 0)
                speed = 9600;

        base_bauds = clock / 16;
        dll = base_bauds / speed;

        if (comport) {
                udbg_comport = (struct NS16550 __iomem *)comport;
                out_8(&udbg_comport->lcr, 0x00);
                out_8(&udbg_comport->ier, 0xff);
                out_8(&udbg_comport->ier, 0x00);
                out_8(&udbg_comport->lcr, LCR_DLAB);
                out_8(&udbg_comport->dll, dll & 0xff);
                out_8(&udbg_comport->dlm, dll >> 8);
                /* 8 data, 1 stop, no parity */
                out_8(&udbg_comport->lcr, 0x03);
                /* RTS/DTR */
                out_8(&udbg_comport->mcr, 0x03);
                /* Clear & enable FIFOs */
                out_8(&udbg_comport->fcr ,0x07);
                udbg_putc = udbg_550_putc;
                udbg_getc = udbg_550_getc;
                udbg_getc_poll = udbg_550_getc_poll;
        }
}

unsigned int udbg_probe_uart_speed(void __iomem *comport, unsigned int clock)
{
        unsigned int dll, dlm, divisor, prescaler, speed;
        u8 old_lcr;
        volatile struct NS16550 __iomem *port = comport;

        old_lcr = in_8(&port->lcr);

        /* select divisor latch registers.  */
        out_8(&port->lcr, LCR_DLAB);

        /* now, read the divisor */
        dll = in_8(&port->dll);
        dlm = in_8(&port->dlm);
        divisor = dlm << 8 | dll;

        /* check prescaling */
        if (in_8(&port->mcr) & 0x80)
                prescaler = 4;
        else
                prescaler = 1;

        /* restore the LCR */
        out_8(&port->lcr, old_lcr);

        /* calculate speed */
        speed = (clock / prescaler) / (divisor * 16);

        /* sanity check */
        if (speed < 0 || speed > (clock / 16))
                speed = 9600;

        return speed;
}

#ifdef CONFIG_PPC_MAPLE
void udbg_maple_real_putc(char c)
{
        if (udbg_comport) {
                while ((real_readb(&udbg_comport->lsr) & LSR_THRE) == 0)
                        /* wait for idle */;
                real_writeb(c, &udbg_comport->thr); eieio();
                if (c == '\n')
                        udbg_maple_real_putc('\r');
        }
}

void __init udbg_init_maple_realmode(void)
{
        udbg_comport = (volatile struct NS16550 __iomem *)0xf40003f8;

        udbg_putc = udbg_maple_real_putc;
        udbg_getc = NULL;
        udbg_getc_poll = NULL;
}
#endif /* CONFIG_PPC_MAPLE */

#ifdef CONFIG_PPC_PASEMI
void udbg_pas_real_putc(char c)
{
        if (udbg_comport) {
                while ((real_205_readb(&udbg_comport->lsr) & LSR_THRE) == 0)
                        /* wait for idle */;
                real_205_writeb(c, &udbg_comport->thr); eieio();
                if (c == '\n')
                        udbg_pas_real_putc('\r');
        }
}

void udbg_init_pas_realmode(void)
{
        udbg_comport = (volatile struct NS16550 __iomem *)0xfcff03f8UL;

        udbg_putc = udbg_pas_real_putc;
        udbg_getc = NULL;
        udbg_getc_poll = NULL;
}
#endif /* CONFIG_PPC_MAPLE */

#ifdef CONFIG_PPC_EARLY_DEBUG_44x
#include <platforms/44x/44x.h>

static void udbg_44x_as1_putc(char c)
{
        if (udbg_comport) {
                while ((as1_readb(&udbg_comport->lsr) & LSR_THRE) == 0)
                        /* wait for idle */;
                as1_writeb(c, &udbg_comport->thr); eieio();
                if (c == '\n')
                        udbg_44x_as1_putc('\r');
        }
}

static int udbg_44x_as1_getc(void)
{
        if (udbg_comport) {
                while ((as1_readb(&udbg_comport->lsr) & LSR_DR) == 0)
                        ; /* wait for char */
                return as1_readb(&udbg_comport->rbr);
        }
        return -1;
}

void __init udbg_init_44x_as1(void)
{
        udbg_comport =
                (volatile struct NS16550 __iomem *)PPC44x_EARLY_DEBUG_VIRTADDR;

        udbg_putc = udbg_44x_as1_putc;
        udbg_getc = udbg_44x_as1_getc;
}
#endif /* CONFIG_PPC_EARLY_DEBUG_44x */