/* gdb-io.c: FR403 GDB stub I/O
 *
 * Copyright (C) 2003 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * 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/string.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/console.h>
#include <linux/init.h>
#include <linux/serial_reg.h>

#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/irc-regs.h>
#include <asm/timer-regs.h>
#include <asm/gdb-stub.h>
#include "gdb-io.h"

#ifdef CONFIG_GDBSTUB_UART0
#define __UART(X) (*(volatile uint8_t *)(UART0_BASE + (UART_##X)))
#define __UART_IRR_NMI 0xff0f0000
#else /* CONFIG_GDBSTUB_UART1 */
#define __UART(X) (*(volatile uint8_t *)(UART1_BASE + (UART_##X)))
#define __UART_IRR_NMI 0xfff00000
#endif

#define LSR_WAIT_FOR(STATE)                     \
do {                                            \
        gdbstub_do_rx();                        \
} while (!(__UART(LSR) & UART_LSR_##STATE))

#define FLOWCTL_QUERY(LINE)     ({ __UART(MSR) & UART_MSR_##LINE; })
#define FLOWCTL_CLEAR(LINE)     do { __UART(MCR) &= ~UART_MCR_##LINE; mb(); } while (0)
#define FLOWCTL_SET(LINE)       do { __UART(MCR) |= UART_MCR_##LINE;  mb(); } while (0)

#define FLOWCTL_WAIT_FOR(LINE)                  \
do {                                            \
        gdbstub_do_rx();                        \
} while(!FLOWCTL_QUERY(LINE))

/*****************************************************************************/
/*
 * initialise the GDB stub
 * - called with PSR.ET==0, so can't incur external interrupts
 */
void gdbstub_io_init(void)
{
        /* set up the serial port */
        __UART(LCR) = UART_LCR_WLEN8; /* 1N8 */
        __UART(FCR) =
                UART_FCR_ENABLE_FIFO |
                UART_FCR_CLEAR_RCVR |
                UART_FCR_CLEAR_XMIT |
                UART_FCR_TRIGGER_1;

        FLOWCTL_CLEAR(DTR);
        FLOWCTL_SET(RTS);

//      gdbstub_set_baud(115200);

        /* we want to get serial receive interrupts */
        __UART(IER) = UART_IER_RDI | UART_IER_RLSI;
        mb();

        __set_IRR(6, __UART_IRR_NMI);   /* map ERRs and UARTx to NMI */

} /* end gdbstub_io_init() */

/*****************************************************************************/
/*
 * set up the GDB stub serial port baud rate timers
 */
void gdbstub_set_baud(unsigned baud)
{
        unsigned value, high, low;
        u8 lcr;

        /* work out the divisor to give us the nearest higher baud rate */
        value = __serial_clock_speed_HZ / 16 / baud;

        /* determine the baud rate range */
        high = __serial_clock_speed_HZ / 16 / value;
        low = __serial_clock_speed_HZ / 16 / (value + 1);

        /* pick the nearest bound */
        if (low + (high - low) / 2 > baud)
                value++;

        lcr = __UART(LCR);
        __UART(LCR) |= UART_LCR_DLAB;
        mb();
        __UART(DLL) = value & 0xff;
        __UART(DLM) = (value >> 8) & 0xff;
        mb();
        __UART(LCR) = lcr;
        mb();

} /* end gdbstub_set_baud() */

/*****************************************************************************/
/*
 * receive characters into the receive FIFO
 */
void gdbstub_do_rx(void)
{
        unsigned ix, nix;

        ix = gdbstub_rx_inp;

        while (__UART(LSR) & UART_LSR_DR) {
                nix = (ix + 2) & 0xfff;
                if (nix == gdbstub_rx_outp)
                        break;

                gdbstub_rx_buffer[ix++] = __UART(LSR);
                gdbstub_rx_buffer[ix++] = __UART(RX);
                ix = nix;
        }

        gdbstub_rx_inp = ix;

        __clr_RC(15);
        __clr_IRL();

} /* end gdbstub_do_rx() */

/*****************************************************************************/
/*
 * wait for a character to come from the debugger
 */
int gdbstub_rx_char(unsigned char *_ch, int nonblock)
{
        unsigned ix;
        u8 ch, st;

        *_ch = 0xff;

        if (gdbstub_rx_unget) {
                *_ch = gdbstub_rx_unget;
                gdbstub_rx_unget = 0;
                return 0;
        }

 try_again:
        gdbstub_do_rx();

        /* pull chars out of the buffer */
        ix = gdbstub_rx_outp;
        if (ix == gdbstub_rx_inp) {
                if (nonblock)
                        return -EAGAIN;
                //watchdog_alert_counter = 0;
                goto try_again;
        }

        st = gdbstub_rx_buffer[ix++];
        ch = gdbstub_rx_buffer[ix++];
        gdbstub_rx_outp = ix & 0x00000fff;

        if (st & UART_LSR_BI) {
                gdbstub_proto("### GDB Rx Break Detected ###\n");
                return -EINTR;
        }
        else if (st & (UART_LSR_FE|UART_LSR_OE|UART_LSR_PE)) {
                gdbstub_proto("### GDB Rx Error (st=%02x) ###\n",st);
                return -EIO;
        }
        else {
                gdbstub_proto("### GDB Rx %02x (st=%02x) ###\n",ch,st);
                *_ch = ch & 0x7f;
                return 0;
        }

} /* end gdbstub_rx_char() */

/*****************************************************************************/
/*
 * send a character to the debugger
 */
void gdbstub_tx_char(unsigned char ch)
{
        FLOWCTL_SET(DTR);
        LSR_WAIT_FOR(THRE);
//      FLOWCTL_WAIT_FOR(CTS);

        if (ch == 0x0a) {
                __UART(TX) = 0x0d;
                mb();
                LSR_WAIT_FOR(THRE);
//              FLOWCTL_WAIT_FOR(CTS);
        }
        __UART(TX) = ch;
        mb();

        FLOWCTL_CLEAR(DTR);
} /* end gdbstub_tx_char() */

/*****************************************************************************/
/*
 * send a character to the debugger
 */
void gdbstub_tx_flush(void)
{
        LSR_WAIT_FOR(TEMT);
        LSR_WAIT_FOR(THRE);
        FLOWCTL_CLEAR(DTR);
} /* end gdbstub_tx_flush() */