68328serial.c

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/* 68328serial.c: Serial port driver for 68328 microcontroller
 *
 * Copyright (C) 1995       David S. Miller    <[e-mail]>
 * Copyright (C) 1998       Kenneth Albanowski <[e-mail]>
 * Copyright (C) 1998, 1999 D. Jeff Dionne     <[e-mail]>
 * Copyright (C) 1999       Vladimir Gurevich  <[e-mail]>
 *
 * VZ Support/Fixes             Evan Stawnyczy <[e-mail]>
 * Multiple UART support        Daniel Potts <[e-mail]>
 */
 
#include <asm/dbg.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/config.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/console.h>
#include <linux/reboot.h>
#include <linux/keyboard.h>
#include <linux/init.h>

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

/* (es) */
/* note: perhaps we can murge these files, so that you can just
 * 	 define 1 of them, and they can sort that out for themselves
 */
#if defined(CONFIG_M68EZ328)
#include <asm/MC68EZ328.h>
#else
#if defined(CONFIG_M68VZ328)
#include <asm/MC68VZ328.h>
#else
#include <asm/MC68328.h>
#endif /* CONFIG_M68VZ328 */
#endif /* CONFIG_M68EZ328 */

#include "68328serial.h"

/* Turn off usage of real serial interrupt code, to "support" Copilot */
#ifdef CONFIG_XCOPILOT_BUGS
#undef USE_INTS
#else
#define USE_INTS
#endif

static struct m68k_serial m68k_soft[NR_PORTS];
struct m86k_serial *IRQ_ports[NR_IRQS];

static unsigned int uart_irqs[NR_PORTS] = UART_IRQ_DEFNS;

/* multiple ports are contiguous in memory */
m68328_uart *uart_addr = USTCNT_ADDR;

struct tty_struct m68k_ttys;
struct m68k_serial *m68k_consinfo = 0;

#define M68K_CLOCK (16667000) /* FIXME: 16MHz is likely wrong */

DECLARE_TASK_QUEUE(tq_serial);

#ifdef CONFIG_CONSOLE
extern wait_queue_head_t keypress_wait; 
#endif

struct tty_driver serial_driver, callout_driver;
static int serial_refcount;

/* serial subtype definitions */
#define SERIAL_TYPE_NORMAL	1
#define SERIAL_TYPE_CALLOUT	2
  
/* number of characters left in xmit buffer before we ask for more */
#define WAKEUP_CHARS 256

/* Debugging... DEBUG_INTR is bad to use when one of the zs
 * lines is your console ;(
 */
#undef SERIAL_DEBUG_INTR
#undef SERIAL_DEBUG_OPEN
#undef SERIAL_DEBUG_FLOW

#define RS_ISR_PASS_LIMIT 256

#define _INLINE_ inline

static void change_speed(struct m68k_serial *info);

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

/*
 *	Setup for console. Argument comes from the boot command line.
 */

#if defined(CONFIG_M68EZ328ADS) || defined(CONFIG_ALMA_ANS)
#define	CONSOLE_BAUD_RATE	115200
#define	DEFAULT_CBAUD		B115200
#endif

/* (es) */
/* note: this is messy, but it works, again, perhaps defined somewhere else?*/
#ifdef CONFIG_M68VZ328
#define CONSOLE_BAUD_RATE	19200
#define DEFAULT_CBAUD		B19200
#endif
/* (/es) */

#ifndef CONSOLE_BAUD_RATE
#define	CONSOLE_BAUD_RATE	9600
#define	DEFAULT_CBAUD		B9600
#endif


static int m68328_console_initted = 0;
static int m68328_console_baud    = CONSOLE_BAUD_RATE;
static int m68328_console_cbaud   = DEFAULT_CBAUD;


/*
 * tmp_buf is used as a temporary buffer by serial_write.  We need to
 * lock it in case the memcpy_fromfs 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[SERIAL_XMIT_SIZE]; /* This is cheating */
DECLARE_MUTEX(tmp_buf_sem);

static inline int serial_paranoia_check(struct m68k_serial *info,
					dev_t device, const char *routine)
{
#ifdef SERIAL_PARANOIA_CHECK
	static const char *badmagic =
		"Warning: bad magic number for serial struct (%d, %d) in %s\n";
	static const char *badinfo =
		"Warning: null m68k_serial for (%d, %d) in %s\n";

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

/*
 * This is used to figure out the divisor speeds and the timeouts
 */
static int baud_table[] = {
	0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
	9600, 19200, 38400, 57600, 115200, 0 };

#define BAUD_TABLE_SIZE (sizeof(baud_table)/sizeof(baud_table[0]))

/* Sets or clears DTR/RTS on the requested line */
static inline void m68k_rtsdtr(struct m68k_serial *ss, int set)
{
	if (set) {
		/* set the RTS/CTS line */
	} else {
		/* clear it */
	}
	return;
}

/* Utility routines */
static inline int get_baud(struct m68k_serial *ss)
{
	unsigned long result = 115200;
	unsigned short int baud = uart_addr[ss->line].ubaud;
	if (GET_FIELD(baud, UBAUD_PRESCALER) == 0x38) result = 38400;
	result >>= GET_FIELD(baud, UBAUD_DIVIDE);

	return result;
}

/*
 * ------------------------------------------------------------
 * 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 m68k_serial *info = (struct m68k_serial *)tty->driver_data;
	m68328_uart *uart = &uart_addr[info->line];
	unsigned long flags;

	if (serial_paranoia_check(info, tty->device, "rs_stop"))
		return;
	
	save_flags(flags); cli();
	uart->ustcnt &= ~USTCNT_TXEN;
	restore_flags(flags);
}

static void rs_put_char(char ch)
{
        int flags, loops = 0;

        save_flags(flags); cli();

	while (!(UTX & UTX_TX_AVAIL) && (loops < 1000)) {
        	loops++;
        	udelay(5);
        }

	UTX_TXDATA = ch;
        udelay(5);
        restore_flags(flags);
}

static void rs_start(struct tty_struct *tty)
{
	struct m68k_serial *info = (struct m68k_serial *)tty->driver_data;
	m68328_uart *uart = &uart_addr[info->line];
	unsigned long flags;
	
	if (serial_paranoia_check(info, tty->device, "rs_start"))
		return;
	
	save_flags(flags); cli();
	if (info->xmit_cnt && info->xmit_buf && !(uart->ustcnt & USTCNT_TXEN)) {
#ifdef USE_INTS
		uart->ustcnt |= USTCNT_TXEN | USTCNT_TX_INTR_MASK;
#else
		uart->ustcnt |= USTCNT_TXEN;
#endif
	}
	restore_flags(flags);
}

/* Drop into either the boot monitor or kadb upon receiving a break
 * from keyboard/console input.
 */
static void batten_down_hatches(void)
{
	/* Drop into the debugger */
}

static _INLINE_ void status_handle(struct m68k_serial *info, unsigned short status)
{
#if 0
	if(status & DCD) {
		if((info->tty->termios->c_cflag & CRTSCTS) &&
		   ((info->curregs[3] & AUTO_ENAB)==0)) {
			info->curregs[3] |= AUTO_ENAB;
			info->pendregs[3] |= AUTO_ENAB;
			write_zsreg(info->m68k_channel, 3, info->curregs[3]);
		}
	} else {
		if((info->curregs[3] & AUTO_ENAB)) {
			info->curregs[3] &= ~AUTO_ENAB;
			info->pendregs[3] &= ~AUTO_ENAB;
			write_zsreg(info->m68k_channel, 3, info->curregs[3]);
		}
	}
#endif
	/* If this is console input and this is a
	 * 'break asserted' status change interrupt
	 * see if we can drop into the debugger
	 */
	if((status & URX_BREAK) && info->break_abort)
		batten_down_hatches();
	return;
}

/*
 * 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 m68k_serial *info,
				    int event)
{
	info->event |= 1 << event;
	queue_task(&info->tqueue, &tq_serial);
	mark_bh(SERIAL_BH);
}

static _INLINE_ void receive_chars(struct m68k_serial *info, struct pt_regs *regs, unsigned short rx)
{
	struct tty_struct *tty = info->tty;
	m68328_uart *uart = &uart_addr[info->line];
	unsigned char ch;

	/*
	 * This do { } while() loop will get ALL chars out of Rx FIFO 
         */
#ifndef CONFIG_XCOPILOT_BUGS
	do {
#endif	
		ch = GET_FIELD(rx, URX_RXDATA);
	
		if(info->is_cons) {
			if(URX_BREAK & rx) { /* whee, break received */
				status_handle(info, rx);
				return;
#ifdef CONFIG_MAGIC_SYSRQ
			} else if (ch == 0x10) { /* ^P */
				show_state();
				show_free_areas();
				show_buffers();
/*				show_net_buffers(); */
				return;
			} else if (ch == 0x12) { /* ^R */
				machine_restart(NULL);
				return;
#endif /* CONFIG_MAGIC_SYSRQ */
			}
			/* It is a 'keyboard interrupt' ;-) */
#ifdef CONFIG_CONSOLE
			wake_up(&keypress_wait);
#endif			
		}

		if(!tty)
			goto clear_and_exit;
		
		/*
		 * Make sure that we do not overflow the buffer
		 */
		if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
			queue_task(&tty->flip.tqueue, &tq_timer);
			return;
		}

		if(rx & URX_PARITY_ERROR) {
			*tty->flip.flag_buf_ptr++ = TTY_PARITY;
			status_handle(info, rx);
		} else if(rx & URX_OVRUN) {
			*tty->flip.flag_buf_ptr++ = TTY_OVERRUN;
			status_handle(info, rx);
		} else if(rx & URX_FRAME_ERROR) {
			*tty->flip.flag_buf_ptr++ = TTY_FRAME;
			status_handle(info, rx);
		} else {
			*tty->flip.flag_buf_ptr++ = 0; /* XXX */
		}
                *tty->flip.char_buf_ptr++ = ch;
		tty->flip.count++;

#ifndef CONFIG_XCOPILOT_BUGS
	} while((rx = uart->urx.w) & URX_DATA_READY);
#endif

	queue_task(&tty->flip.tqueue, &tq_timer);

clear_and_exit:
	return;
}

static _INLINE_ void transmit_chars(struct m68k_serial *info)
{
	m68328_uart *uart = &uart_addr[info->line];

	if (info->x_char) {
		/* Send next char */
		uart->utx.b.txdata = info->x_char;
		info->x_char = 0;
		goto clear_and_return;
	}

	if((info->xmit_cnt <= 0) || info->tty->stopped) {
		/* That's peculiar... TX ints off */
		uart->ustcnt &= ~USTCNT_TX_INTR_MASK;
		goto clear_and_return;
	}

	/* Send char */
	uart->utx.b.txdata = info->xmit_buf[info->xmit_tail++];
	info->xmit_tail = info->xmit_tail & (SERIAL_XMIT_SIZE-1);
	info->xmit_cnt--;

	if (info->xmit_cnt < WAKEUP_CHARS)
		rs_sched_event(info, RS_EVENT_WRITE_WAKEUP);

	if(info->xmit_cnt <= 0) {
		/* All done for now... TX ints off */
		uart->ustcnt &= ~USTCNT_TX_INTR_MASK;
		goto clear_and_return;
	}

clear_and_return:
	/* Clear interrupt (should be auto)*/
	return;
}

/*
 * This is the serial driver's generic interrupt routine
 */
void rs_interrupt(int irq, void *dev_id, struct pt_regs * regs)
{
	struct m68k_serial * info;
	m68328_uart *uart;
	unsigned short rx;
	unsigned short tx;

	info = IRQ_ports[irq];
	if(!info)
	    return;

	uart = &uart_addr[info->line];
	rx = uart->urx.w;

#ifdef USE_INTS
	tx = uart->utx.w;

	if (rx & URX_DATA_READY) receive_chars(info, regs, rx);
	if (tx & UTX_TX_AVAIL)   transmit_chars(info);
#else
	receive_chars(info, regs, rx);		
#endif
	return;
}

/*
 * 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 m68k_serial	*info = (struct m68k_serial *) private_;
	struct tty_struct	*tty;
	
	tty = info->tty;
	if (!tty)
		return;
#if 0
	if (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);
	}
#endif   
}

/*
 * 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_)
{
	struct m68k_serial	*info = (struct m68k_serial *) private_;
	struct tty_struct	*tty;
	
	tty = info->tty;
	if (!tty)
		return;

	tty_hangup(tty);
}


static int startup(struct m68k_serial * info)
{
	m68328_uart *uart = &uart_addr[info->line];
	unsigned long flags;
	
	if (info->flags & S_INITIALIZED)
		return 0;

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

	save_flags(flags); cli();

	/*
	 * Clear the FIFO buffers and disable them
	 * (they will be reenabled in change_speed())
	 */

	uart->ustcnt = USTCNT_UEN;
	info->xmit_fifo_size = 1;
	uart->ustcnt = USTCNT_UEN | USTCNT_RXEN | USTCNT_TXEN;
	(void)uart->urx.w;

	/*
	 * Finally, enable sequencing and interrupts
	 */
#ifdef USE_INTS
	uart->ustcnt = USTCNT_UEN | USTCNT_RXEN | 
                 USTCNT_RX_INTR_MASK | USTCNT_TX_INTR_MASK;
#else
	uart->ustcnt = USTCNT_UEN | USTCNT_RXEN | USTCNT_RX_INTR_MASK;
#endif

	if (info->tty)
		clear_bit(TTY_IO_ERROR, &info->tty->flags);
	info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;

	/*
	 * and set the speed of the serial port
	 */

	change_speed(info);

	info->flags |= S_INITIALIZED;
	restore_flags(flags);
	return 0;
}

/*
 * 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 m68k_serial * info)
{