amiserial.c

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/*
 *  linux/drivers/char/amiserial.c
 *
 * Serial driver for the amiga builtin port.
 *
 * This code was created by taking serial.c version 4.30 from kernel
 * release 2.3.22, replacing all hardware related stuff with the
 * corresponding amiga hardware actions, and removing all irrelevant
 * code. As a consequence, it uses many of the constants and names
 * associated with the registers and bits of 16550 compatible UARTS -
 * but only to keep track of status, etc in the state variables. It
 * was done this was to make it easier to keep the code in line with
 * (non hardware specific) changes to serial.c.
 *
 * The port is registered with the tty driver as minor device 64, and
 * therefore other ports should should only use 65 upwards.
 *
 * Richard Lucock 28/12/99
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 
 * 		1998, 1999  Theodore Ts'o
 *
 */

/*
 * Serial driver configuration section.  Here are the various options:
 *
 * SERIAL_PARANOIA_CHECK
 * 		Check the magic number for the async_structure where
 * 		ever possible.
 */

#include <linux/config.h>
#include <linux/version.h>

#undef SERIAL_PARANOIA_CHECK
#define SERIAL_DO_RESTART

/* Set of debugging defines */

#undef SERIAL_DEBUG_INTR
#undef SERIAL_DEBUG_OPEN
#undef SERIAL_DEBUG_FLOW
#undef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT

/* Sanity checks */

#define SERIAL_INLINE
  
#if defined(MODULE) && defined(SERIAL_DEBUG_MCOUNT)
#define DBG_CNT(s) printk("(%s): [%x] refc=%d, serc=%d, ttyc=%d -> %s\n", \
 kdevname(tty->device), (info->flags), serial_refcount,info->count,tty->count,s)
#else
#define DBG_CNT(s)
#endif

/*
 * End of serial driver configuration section.
 */

#ifdef MODVERSIONS
#include <linux/modversions.h>
#endif
#include <linux/module.h>

#include <linux/types.h>
#include <linux/serial.h>
#include <linux/serialP.h>
#include <linux/serial_reg.h>
static char *serial_version = "4.30";

#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/console.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/ptrace.h>
#include <linux/ioport.h>
#include <linux/mm.h>
#include <linux/malloc.h>
#include <linux/init.h>
#include <linux/delay.h>

#include <asm/setup.h>

#include <asm/system.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/bitops.h>

#include <asm/amigahw.h>
#include <asm/amigaints.h>

#ifdef SERIAL_INLINE
#define _INLINE_ inline
#endif

static char *serial_name = "Amiga-builtin serial driver";

static DECLARE_TASK_QUEUE(tq_serial);

static struct tty_driver serial_driver, callout_driver;
static int serial_refcount;

/* serial subtype definitions */
#ifndef SERIAL_TYPE_NORMAL
#define SERIAL_TYPE_NORMAL	1
#define SERIAL_TYPE_CALLOUT	2
#endif

/* number of characters left in xmit buffer before we ask for more */
#define WAKEUP_CHARS 256

static struct async_struct *IRQ_ports;

static unsigned char current_ctl_bits;

static void change_speed(struct async_struct *info, struct termios *old);
static void rs_wait_until_sent(struct tty_struct *tty, int timeout);


static struct serial_state rs_table[1];

#define NR_PORTS	(sizeof(rs_table)/sizeof(struct serial_state))


static struct tty_struct *serial_table[NR_PORTS];
static struct termios *serial_termios[NR_PORTS];
static struct termios *serial_termios_locked[NR_PORTS];

#ifndef MIN
#define MIN(a,b)	((a) < (b) ? (a) : (b))
#endif

/*
 * tmp_buf is used as a temporary buffer by serial_write.  We need to
 * lock it in case the copy_from_user blocks while swapping in a page,
 * and some other program tries to do a serial write at the same time.
 * Since the lock will only come under contention when the system is
 * swapping and available memory is low, it makes sense to share one
 * buffer across all the serial ports, since it significantly saves
 * memory if large numbers of serial ports are open.
 */
static unsigned char *tmp_buf;
static DECLARE_MUTEX(tmp_buf_sem);

#include <asm/uaccess.h>

#define serial_isroot()	(capable(CAP_SYS_ADMIN))


static inline int serial_paranoia_check(struct async_struct *info,
					kdev_t device, const char *routine)
{
#ifdef SERIAL_PARANOIA_CHECK
	static const char *badmagic =
		"Warning: bad magic number for serial struct (%s) in %s\n";
	static const char *badinfo =
		"Warning: null async_struct for (%s) in %s\n";

	if (!info) {
		printk(badinfo, kdevname(device), routine);
		return 1;
	}
	if (info->magic != SERIAL_MAGIC) {
		printk(badmagic, kdevname(device), routine);
		return 1;
	}
#endif
	return 0;
}

/* some serial hardware definitions */
#define SDR_OVRUN   (1<<15)
#define SDR_RBF     (1<<14)
#define SDR_TBE     (1<<13)
#define SDR_TSRE    (1<<12)

#define SERPER_PARENB    (1<<15)

#define AC_SETCLR   (1<<15)
#define AC_UARTBRK  (1<<11)

#define SER_DTR     (1<<7)
#define SER_RTS     (1<<6)
#define SER_DCD     (1<<5)
#define SER_CTS     (1<<4)
#define SER_DSR     (1<<3)

static __inline__ void rtsdtr_ctrl(int bits)
{
    ciab.pra = ((bits & (SER_RTS | SER_DTR)) ^ (SER_RTS | SER_DTR)) | (ciab.pra & ~(SER_RTS | SER_DTR));
}

/*
 * ------------------------------------------------------------
 * rs_stop() and rs_start()
 *
 * This routines are called before setting or resetting tty->stopped.
 * They enable or disable transmitter interrupts, as necessary.
 * ------------------------------------------------------------
 */
static void rs_stop(struct tty_struct *tty)
{
	struct async_struct *info = (struct async_struct *)tty->driver_data;
	unsigned long flags;

	if (serial_paranoia_check(info, tty->device, "rs_stop"))
		return;

	save_flags(flags); cli();
	if (info->IER & UART_IER_THRI) {
		info->IER &= ~UART_IER_THRI;
		/* disable Tx interrupt and remove any pending interrupts */
		custom.intena = IF_TBE;
		mb();
		custom.intreq = IF_TBE;
		mb();
	}
	restore_flags(flags);
}

static void rs_start(struct tty_struct *tty)
{
	struct async_struct *info = (struct async_struct *)tty->driver_data;
	unsigned long flags;

	if (serial_paranoia_check(info, tty->device, "rs_start"))
		return;

	save_flags(flags); cli();
	if (info->xmit.head != info->xmit.tail
	    && info->xmit.buf
	    && !(info->IER & UART_IER_THRI)) {
		info->IER |= UART_IER_THRI;
		custom.intena = IF_SETCLR | IF_TBE;
		mb();
		/* set a pending Tx Interrupt, transmitter should restart now */
		custom.intreq = IF_SETCLR | IF_TBE;
		mb();
	}
	restore_flags(flags);
}

/*
 * ----------------------------------------------------------------------
 *
 * Here starts the interrupt handling routines.  All of the following
 * subroutines are declared as inline and are folded into
 * rs_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 serial.c
 *
 * and look at the resulting assemble code in serial.s.
 *
 * 				- Ted Ts'o ([e-mail]), 7-Mar-93
 * -----------------------------------------------------------------------
 */

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

static _INLINE_ void receive_chars(struct async_struct *info)
{
        int status;
	int serdatr;
	struct tty_struct *tty = info->tty;
	unsigned char ch;
	struct	async_icount *icount;

	icount = &info->state->icount;

	status = UART_LSR_DR; /* We obviously have a character! */
	serdatr = custom.serdatr;
	mb();
	custom.intreq = IF_RBF;
	mb();

	if((serdatr & 0x1ff) == 0)
	    status |= UART_LSR_BI;
	if(serdatr & SDR_OVRUN)
	    status |= UART_LSR_OE;

	ch = serdatr & 0xff;
	if (tty->flip.count >= TTY_FLIPBUF_SIZE)
	  goto ignore_char;
	*tty->flip.char_buf_ptr = ch;
	icount->rx++;

#ifdef SERIAL_DEBUG_INTR
	printk("DR%02x:%02x...", ch, status);
#endif
	*tty->flip.flag_buf_ptr = 0;

	/*
	 * We don't handle parity or frame errors - but I have left
	 * the code in, since I'm not sure that the errors can't be
	 * detected.
	 */

	if (status & (UART_LSR_BI | UART_LSR_PE |
		      UART_LSR_FE | UART_LSR_OE)) {
	  /*
	   * For statistics only
	   */
	  if (status & UART_LSR_BI) {
	    status &= ~(UART_LSR_FE | UART_LSR_PE);
	    icount->brk++;
	  } else if (status & UART_LSR_PE)
	    icount->parity++;
	  else if (status & UART_LSR_FE)
	    icount->frame++;
	  if (status & UART_LSR_OE)
	    icount->overrun++;

	  /*
	   * Now check to see if character should be
	   * ignored, and mask off conditions which
	   * should be ignored.
	   */
	  if (status & info->ignore_status_mask)
	    goto ignore_char;

	  status &= info->read_status_mask;

	  if (status & (UART_LSR_BI)) {
#ifdef SERIAL_DEBUG_INTR
	    printk("handling break....");
#endif
	    *tty->flip.flag_buf_ptr = TTY_BREAK;
	    if (info->flags & ASYNC_SAK)
	      do_SAK(tty);
	  } else if (status & UART_LSR_PE)
	    *tty->flip.flag_buf_ptr = TTY_PARITY;
	  else if (status & UART_LSR_FE)
	    *tty->flip.flag_buf_ptr = TTY_FRAME;
	  if (status & UART_LSR_OE) {
	    /*
	     * Overrun is special, since it's
	     * reported immediately, and doesn't
	     * affect the current character
	     */
	    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:

	tty_flip_buffer_push(tty);
}

static _INLINE_ void transmit_chars(struct async_struct *info)
{
	custom.intreq = IF_TBE;
	mb();
	if (info->x_char) {
	        custom.serdat = info->x_char | 0x100;
		mb();
		info->state->icount.tx++;
		info->x_char = 0;
		return;
	}
	if (info->xmit.head == info->xmit.tail
	    || info->tty->stopped
	    || info->tty->hw_stopped) {
		info->IER &= ~UART_IER_THRI;
	        custom.intena = IF_TBE;
		mb();
		return;
	}

	custom.serdat = info->xmit.buf[info->xmit.tail++] | 0x100;
	mb();
	info->xmit.tail = info->xmit.tail & (SERIAL_XMIT_SIZE-1);
	info->state->icount.tx++;

	if (CIRC_CNT(info->xmit.head,
		     info->xmit.tail,
		     SERIAL_XMIT_SIZE) < WAKEUP_CHARS)
		rs_sched_event(info, RS_EVENT_WRITE_WAKEUP);

#ifdef SERIAL_DEBUG_INTR
	printk("THRE...");
#endif
	if (info->xmit.head == info->xmit.tail) {
	        custom.intena = IF_TBE;
		mb();
		info->IER &= ~UART_IER_THRI;
	}
}

static _INLINE_ void check_modem_status(struct async_struct *info)
{
	unsigned char status = ciab.pra & (SER_DCD | SER_CTS | SER_DSR);
	unsigned char dstatus;
	struct	async_icount *icount;

	/* Determine bits that have changed */
	dstatus = status ^ current_ctl_bits;
	current_ctl_bits = status;

	if (dstatus) {
		icount = &info->state->icount;
		/* update input line counters */
		if (dstatus & SER_DSR)
			icount->dsr++;
		if (dstatus & SER_DCD) {
			icount->dcd++;
#ifdef CONFIG_HARD_PPS
			if ((info->flags & ASYNC_HARDPPS_CD) &&
			    !(status & SER_DCD))
				hardpps();
#endif
		}
		if (dstatus & SER_CTS)
			icount->cts++;
		wake_up_interruptible(&info->delta_msr_wait);
	}

	if ((info->flags & ASYNC_CHECK_CD) && (dstatus & SER_DCD)) {
#if (defined(SERIAL_DEBUG_OPEN) || defined(SERIAL_DEBUG_INTR))
		printk("ttyS%02d CD now %s...", info->line,
		       (!(status & SER_DCD)) ? "on" : "off");
#endif
		if (!(status & SER_DCD))
			wake_up_interruptible(&info->open_wait);
		else if (!((info->flags & ASYNC_CALLOUT_ACTIVE) &&
			   (info->flags & ASYNC_CALLOUT_NOHUP))) {
#ifdef SERIAL_DEBUG_OPEN
			printk("doing serial hangup...");
#endif
			if (info->tty)
				tty_hangup(info->tty);
		}
	}
	if (info->flags & ASYNC_CTS_FLOW) {
		if (info->tty->hw_stopped) {
			if (!(status & SER_CTS)) {
#if (defined(SERIAL_DEBUG_INTR) || defined(SERIAL_DEBUG_FLOW))
				printk("CTS tx start...");
#endif
				info->tty->hw_stopped = 0;
				info->IER |= UART_IER_THRI;
				custom.intena = IF_SETCLR | IF_TBE;
				mb();
				/* set a pending Tx Interrupt, transmitter should restart now */
				custom.intreq = IF_SETCLR | IF_TBE;
				mb();
				rs_sched_event(info, RS_EVENT_WRITE_WAKEUP);
				return;
			}
		} else {
			if ((status & SER_CTS)) {
#if (defined(SERIAL_DEBUG_INTR) || defined(SERIAL_DEBUG_FLOW))
				printk("CTS tx stop...");
#endif
				info->tty->hw_stopped = 1;
				info->IER &= ~UART_IER_THRI;
				/* disable Tx interrupt and remove any pending interrupts */
				custom.intena = IF_TBE;
				mb();
				custom.intreq = IF_TBE;
				mb();
			}
		}
	}
}

static void ser_vbl_int( int irq, void *data, struct pt_regs *regs)
{
        /* vbl is just a periodic interrupt we tie into to update modem status */
	struct async_struct * info = IRQ_ports;
	/*
	 * TBD - is it better to unregister from this interrupt or to
	 * ignore it if MSI is clear ?
	 */
	if(info->IER & UART_IER_MSI)
	  check_modem_status(info);
}

static void ser_rx_int(int irq, void *dev_id, struct pt_regs * regs)
{
	struct async_struct * info;

#ifdef SERIAL_DEBUG_INTR
	printk("ser_rx_int...");
#endif

	info = IRQ_ports;
	if (!info || !info->tty)
		return;

	receive_chars(info);
	info->last_active = jiffies;
#ifdef SERIAL_DEBUG_INTR
	printk("end.\n");
#endif
}

static void ser_tx_int(int irq, void *dev_id, struct pt_regs * regs)
{
	struct async_struct * info;

	if (custom.serdatr & SDR_TBE) {
#ifdef SERIAL_DEBUG_INTR
	  printk("ser_tx_int...");
#endif

	  info = IRQ_ports;
	  if (!info || !info->tty)
	    return;

	  transmit_chars(info);
	  info->last_active = jiffies;
#ifdef SERIAL_DEBUG_INTR
	  printk("end.\n");
#endif
	}
}

/*
 * -------------------------------------------------------------------
 * Here ends the serial 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_)
{
	struct async_struct	*info = (struct async_struct *) private_;
	struct tty_struct	*tty;

	tty = info->tty;
	if (!tty)
		return;

	if (test_and_clear_bit(RS_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);
	}
}

/*
 * ---------------------------------------------------------------
 * Low level utility subroutines for the serial driver:  routines to