dz.c

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/*
 * dz.c: Serial port driver for DECStations equiped 
 *       with the DZ chipset.
 *
 * Copyright (C) 1998 Olivier A. D. Lebaillif 
 *             
 * Email: [e-mail]
 *
 * [31-AUG-98] triemer
 * Changed IRQ to use Harald's dec internals interrupts.h
 * removed base_addr code - moving address assignment to setup.c
 * Changed name of dz_init to rs_init to be consistent with tc code
 * [13-NOV-98] triemer fixed code to receive characters
 *    after patches by harald to irq code.  
 * [09-JAN-99] triemer minor fix for schedule - due to removal of timeout
 *            field from "current" - somewhere between 2.1.121 and 2.1.131
 *  
 * Parts (C) 1999 David Airlie, [e-mail] 
 * [07-SEP-99] Bugfixes 
 */

#define DEBUG_DZ 1

#ifdef MODULE
#include <linux/module.h>
#include <linux/version.h>
#else
#define MOD_INC_USE_COUNT
#define MOD_DEC_USE_COUNT
#endif

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/init.h> 
#include <linux/malloc.h>
#include <linux/mm.h>
#include <linux/major.h>
#include <linux/param.h>
#include <linux/tqueue.h>
#include <linux/interrupt.h>
#include <asm-mips/wbflush.h>
/* for definition of SERIAL */
#include <asm/dec/interrupts.h>

/* for definition of struct console */
#ifdef CONFIG_SERIAL_CONSOLE
#define CONSOLE_LINE (3)
#endif /* ifdef CONFIG_SERIAL_CONSOLE */
#if defined(CONFIG_SERIAL_CONSOLE) || defined(DEBUG_DZ)
#include <linux/console.h>
#endif /* if defined(CONFIG_SERIAL_CONSOLE) || defined(DEBUG_DZ) */

#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial.h>

#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/dec/machtype.h>
#include <asm/dec/kn01.h>
#include <asm/dec/kn02.h>

#ifdef DEBUG_DZ
#include <linux/ptrace.h>
#include <linux/fs.h>
#include <asm/bootinfo.h>

extern int (*prom_printf) (char *,...);
#endif



#include "dz.h"

#define DZ_INTR_DEBUG 1

DECLARE_TASK_QUEUE(tq_serial);

extern wait_queue_head_t keypress_wait; 
static struct dz_serial *lines[4];
static unsigned char tmp_buffer[256];



#ifdef DEBUG_DZ
/*
 * debugging code to send out chars via prom 
 */
static void debug_console( const char *s,int count)
{
    unsigned i;

    for (i = 0; i < count; i++) {
       if (*s == 10)
           prom_printf("%c", 13);
       prom_printf("%c", *s++);
    }
}
#endif

/*
 * ------------------------------------------------------------
 * dz_in () and dz_out ()
 *
 * These routines are used to access the registers of the DZ 
 * chip, hiding relocation differences between implementation.
 * ------------------------------------------------------------
 */

static inline unsigned short dz_in (struct dz_serial *info, unsigned offset)
{
  volatile unsigned short *addr = (volatile unsigned short *)(info->port + offset);
  return *addr;
}

static inline void dz_out (struct dz_serial *info, unsigned offset, unsigned short value)
{

    volatile unsigned short *addr = (volatile unsigned short *)(info->port + offset);
  *addr = value;

}

/*
 * ------------------------------------------------------------
 * rs_stop () and rs_start ()
 *
 * These routines are called before setting or resetting 
 * tty->stopped. They enable or disable transmitter interrupts, 
 * as necessary.
 * ------------------------------------------------------------
 */

static void dz_stop (struct tty_struct *tty)
{
  struct dz_serial *info; 
  unsigned short mask, tmp;

  if (tty==0) 
    return; 
 
  info = (struct dz_serial *)tty->driver_data; 
         
  mask = 1 << info->line;
  tmp = dz_in (info, DZ_TCR);       /* read the TX flag */

    tmp &= ~mask;                   /* clear the TX flag */
    dz_out (info, DZ_TCR, tmp);
}  

static void dz_start (struct tty_struct *tty)
{
  struct dz_serial *info = (struct dz_serial *)tty->driver_data;
  unsigned short mask, tmp;

  mask = 1 << info->line;
  tmp = dz_in (info, DZ_TCR);      /* read the TX flag */

    tmp |= mask;                   /* set the TX flag */
    dz_out (info, DZ_TCR, tmp);

}  

/*
 * ------------------------------------------------------------
 * Here starts the interrupt handling routines.  All of the 
 * following subroutines are declared as inline and are folded 
 * into dz_interrupt.  They were separated out for readability's 
 * sake. 
 *
 * Note: rs_interrupt() is a "fast" interrupt, which means that it
 * runs with interrupts turned off.  People who may want to modify
 * rs_interrupt() should try to keep the interrupt handler as fast as
 * possible.  After you are done making modifications, it is not a bad
 * idea to do:
 * 
 * gcc -S -DKERNEL -Wall -Wstrict-prototypes -O6 -fomit-frame-pointer dz.c
 *
 * and look at the resulting assemble code in serial.s.
 *
 * ------------------------------------------------------------
 */

/*
 * ------------------------------------------------------------
 * dz_sched_event ()
 *
 * This routine is used by the interrupt handler to schedule
 * processing in the software interrupt portion of the driver.
 * ------------------------------------------------------------
 */
static inline void dz_sched_event (struct dz_serial *info, int event)
{
  info->event |= 1 << event;
  queue_task (&info->tqueue, &tq_serial);
  mark_bh (SERIAL_BH);
}

/*
 * ------------------------------------------------------------
 * receive_char ()
 *
 * This routine deals with inputs from any lines.
 * ------------------------------------------------------------
 */
static inline void receive_chars (struct dz_serial *info_in)
{

  struct dz_serial *info;
  struct tty_struct *tty = 0;
  struct async_icount *icount;
  int ignore = 0;
  unsigned short status, tmp;
  unsigned char ch;

  /* this code is going to be a problem...
     the call to tty_flip_buffer is going to need
     to be rethought...
   */
  do
    {
      status = dz_in (info_in, DZ_RBUF);
      info = lines[LINE(status)];

      /* punt so we don't get duplicate characters */
      if (!(status & DZ_DVAL))
        goto ignore_char;


    ch = UCHAR(status);                /* grab the char */

#ifdef 0
    if (info->is_console) {
      if (ch == 0) return;            /* it's a break ... */

      wake_up (&keypress_wait);       /* It is a 'keyboard interrupt' ;-) */
    }
#endif

    tty = info->tty;                  /* now tty points to the proper dev */
    icount = &info->icount;

    if (!tty) break;
    if (tty->flip.count >= TTY_FLIPBUF_SIZE) break;

    *tty->flip.char_buf_ptr = ch;
    *tty->flip.flag_buf_ptr = 0;
    icount->rx++;

    /* keep track of the statistics */
    if (status & (DZ_OERR | DZ_FERR | DZ_PERR)) {
      if (status & DZ_PERR)                /* parity error */
        icount->parity++;
      else if (status & DZ_FERR)           /* frame error */
        icount->frame++;
      if (status & DZ_OERR)                /* overrun error */
        icount->overrun++;

      /*  check to see if we should ignore the character
	 and mask off conditions that should be ignored
      */

      if (status & info->ignore_status_mask) {
        if (++ignore > 100 ) break;
        goto ignore_char;
      }

      /* mask off the error conditions we want to ignore */
      tmp = status & info->read_status_mask;

      if (tmp & DZ_PERR)
	{
        *tty->flip.flag_buf_ptr = TTY_PARITY;
	  debug_console("PERR\n",5);
	}
      else if (tmp & DZ_FERR)
	{
        *tty->flip.flag_buf_ptr = TTY_FRAME;
	  debug_console("FERR\n",5);
	}
      if (tmp & DZ_OERR) 
	{ 
	  debug_console("OERR\n",5);
	if (tty->flip.count < TTY_FLIPBUF_SIZE) {
          tty->flip.count++;
          tty->flip.flag_buf_ptr++;
          tty->flip.char_buf_ptr++;
          *tty->flip.flag_buf_ptr = TTY_OVERRUN;
        }
      }
    }
    tty->flip.flag_buf_ptr++;
    tty->flip.char_buf_ptr++;
    tty->flip.count++;
  ignore_char:
  } while (status & DZ_DVAL);

  if (tty)
    tty_flip_buffer_push(tty);
}

/*
 * ------------------------------------------------------------
 * transmit_char ()
 *
 * This routine deals with outputs to any lines.
 * ------------------------------------------------------------
 */
static inline void transmit_chars (struct dz_serial *info)
{
  unsigned char tmp;



  if (info->x_char) {           /* XON/XOFF chars */
    dz_out (info, DZ_TDR, info->x_char);
    info->icount.tx++;
    info->x_char = 0;
    return;
  }

  /* if nothing to do or stopped or hardware stopped */
  if ((info->xmit_cnt <= 0) || info->tty->stopped || info->tty->hw_stopped) {
    dz_stop (info->tty);
    return;
  }

  /* if something to do ... (rember the dz has no output fifo so we go one char at a time :-< */
  tmp = (unsigned short)info->xmit_buf[info->xmit_tail++];
  dz_out (info, DZ_TDR, tmp);
  info->xmit_tail = info->xmit_tail & (DZ_XMIT_SIZE - 1);
  info->icount.tx++;

  if (--info->xmit_cnt < WAKEUP_CHARS)
    dz_sched_event (info, DZ_EVENT_WRITE_WAKEUP);


  /* Are we done */
  if (info->xmit_cnt <= 0) dz_stop (info->tty);
}

/*
 * ------------------------------------------------------------
 * check_modem_status ()
 *
 * Only valid for the MODEM line duh !
 * ------------------------------------------------------------
 */
static inline void check_modem_status (struct dz_serial *info)
{
  unsigned short status;

  /* if not ne modem line just return */
  if (info->line != DZ_MODEM) return;

  status = dz_in (info, DZ_MSR);
  
  /* it's easy, since DSR2 is the only bit in the register */
  if (status) info->icount.dsr++;
}

/*
 * ------------------------------------------------------------
 * dz_interrupt ()
 *
 * this is the main interrupt routine for the DZ chip.
 * It deals with the multiple ports.
 * ------------------------------------------------------------
 */
static void dz_interrupt (int irq, void *dev, struct pt_regs *regs)
{
  struct dz_serial *info;
  unsigned short status;

  status = dz_in ((struct dz_serial *)dev, DZ_CSR); /* get the reason why we just got an irq */
  info = lines[LINE(status)];     /* re-arrange info the proper port */

  if (status & DZ_RDONE) 
      receive_chars (info);          /* the receive function */

  if (status & DZ_TRDY) 
    transmit_chars (info);
}

/*
 * -------------------------------------------------------------------
 * Here ends the DZ interrupt routines.
 * -------------------------------------------------------------------
 */

/*
 * This routine is used to handle the "bottom half" processing for the
 * serial driver, known also the "software interrupt" processing.
 * This processing is done at the kernel interrupt level, after the
 * rs_interrupt() has returned, BUT WITH INTERRUPTS TURNED ON.  This
 * is where time-consuming activities which can not be done in the
 * interrupt driver proper are done; the interrupt driver schedules
 * them using rs_sched_event(), and they get done here.
 */
static void do_serial_bh (void)
{
        run_task_queue (&tq_serial);
}

static void do_softint (void *private_data)
{
  struct dz_serial *info = (struct dz_serial *)private_data;
  struct tty_struct *tty = info->tty;

  if (!tty) return;

  if (test_and_clear_bit (DZ_EVENT_WRITE_WAKEUP, &info->event)) {
    if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) && tty->ldisc.write_wakeup)
      (tty->ldisc.write_wakeup) (tty);
    wake_up_interruptible (&tty->write_wait);
  }
}

/*
 * -------------------------------------------------------------------
 * This routine is called from the scheduler tqueue when the interrupt
 * routine has signalled that a hangup has occurred.  The path of
 * hangup processing is:
 *
 *      serial interrupt routine -> (scheduler tqueue) ->
 *      do_serial_hangup() -> tty->hangup() -> rs_hangup()
 * ------------------------------------------------------------------- 
 */
static void do_serial_hangup (void *private_data)
{
  struct dz_serial *info = (struct dz_serial *)private_data;
  struct tty_struct *tty = info->tty;;
        
  if (!tty) return;

  tty_hangup (tty);
}

/*
 * -------------------------------------------------------------------
 * startup ()
 *
 * various initialization tasks
 * ------------------------------------------------------------------- 
 */
static int startup (struct dz_serial *info)
{
  unsigned long page, flags;
  unsigned short tmp;

  if (info->is_initialized) return 0;
  
  save_flags (flags);
  cli ();

  if (!info->port) {
    if (info->tty) set_bit (TTY_IO_ERROR, &info->tty->flags);
    restore_flags (flags);
    return -ENODEV;
  }

  if (!info->xmit_buf) {
    page = get_free_page (GFP_KERNEL);
    if (!page) {
      restore_flags (flags);
      return -ENOMEM;
    }
    info->xmit_buf = (unsigned char *)page;
  }

  if (info->tty) clear_bit (TTY_IO_ERROR, &info->tty->flags);

  /* enable the interrupt and the scanning */
  tmp = dz_in (info, DZ_CSR);
  tmp |= (DZ_RIE | DZ_TIE | DZ_MSE);
  dz_out (info, DZ_CSR, tmp);

  info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;

  /* set up the speed */
  change_speed (info);

  /* clear the line transmitter buffer 
     I can't figure out why I need to do this - but
     its necessary - in order for the console portion
     and the interrupt portion to live happily side by side.
  */

  /* clear the line transmitter buffer 
     I can't figure out why I need to do this - but
     its necessary - in order for the console portion
     and the interrupt portion to live happily side by side.
  */

  info->is_initialized = 1;

  restore_flags (flags);
  return 0;
}

/* 
 * -------------------------------------------------------------------
 * shutdown ()
 *
 * This routine will shutdown a serial port; interrupts are disabled, and
 * DTR is dropped if the hangup on close termio flag is on.
 * ------------------------------------------------------------------- 
 */
static void shutdown (struct dz_serial *info)
{
  unsigned long flags;
  unsigned short tmp;

  if (!info->is_initialized) return;

  save_flags (flags);
  cli ();

  dz_stop (info->tty);



  info->cflags &= ~DZ_CREAD;          /* turn off receive enable flag */