mcfserial.c

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/*
 * mcfserial.c -- serial driver for ColdFire internal UARTS.
 *
 * Copyright (c) 1999-2002 Greg Ungerer <[e-mail]>
 * Copyright (c) 2000-2001 Lineo, Inc. <www.lineo.com> 
 * Copyright (C) 2001-2002 SnapGear Inc. <www.snapgear.com> 
 *
 * Based on code from 68332serial.c which was:
 *
 * Copyright (C) 1995 David S. Miller ([e-mail])
 * Copyright (C) 1998 TSHG
 * Copyright (c) 1999 Rt-Control Inc. <[e-mail]>
 */
 
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/wait.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/serial.h>
#include <linux/serialP.h>
#ifdef CONFIG_LEDMAN
#include <linux/ledman.h>
#endif
#include <linux/console.h>
#include <linux/version.h>
#include <linux/init.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/system.h>
#include <asm/segment.h>
#include <asm/semaphore.h>
#include <asm/bitops.h>
#include <asm/delay.h>
#include <asm/coldfire.h>
#include <asm/mcfsim.h>
#include <asm/mcfuart.h>
#include <asm/nettel.h>
#if LINUX_VERSION_CODE < 0x020100
#define queue_task_irq_off queue_task
#define copy_from_user(a,b,c) memcpy_fromfs(a,b,c)
#define copy_to_user(a,b,c) memcpy_tofs(a,b,c)
#else
#include <asm/uaccess.h>
#endif
#include "mcfserial.h"

/*
 *	the only event we use
 */
#undef RS_EVENT_WRITE_WAKEUP
#define RS_EVENT_WRITE_WAKEUP 0

#if LINUX_VERSION_CODE >= 0x020100
struct timer_list mcfrs_timer_struct;
#endif

/*
 *	Default console baud rate,  we use this as the default
 *	for all ports so init can just open /dev/console and
 *	keep going.  Perhaps one day the cflag settings for the
 *	console can be used instead.
 */
#if defined(CONFIG_ARNEWSH) || defined(CONFIG_MOTOROLA)
#define	CONSOLE_BAUD_RATE	19200
#define	DEFAULT_CBAUD		B19200
#endif

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

int mcfrs_console_inited = 0;
int mcfrs_console_port = -1;
int mcfrs_console_baud = CONSOLE_BAUD_RATE;
int mcfrs_console_cbaud = DEFAULT_CBAUD;

DECLARE_TASK_QUEUE(mcf_tq_serial);

/*
 *	Driver data structures.
 */
struct tty_driver	mcfrs_serial_driver, mcfrs_callout_driver;
static int		mcfrs_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...
 */
#undef SERIAL_DEBUG_OPEN
#undef SERIAL_DEBUG_FLOW

#define _INLINE_ inline

#define	IRQBASE	73

/*
 *	Configuration table, UARTs to look for at startup.
 */
static struct mcf_serial mcfrs_table[] = {
  { 0, (MCF_MBAR+MCFUART_BASE1), IRQBASE,   ASYNC_BOOT_AUTOCONF },  /* ttyS0 */
  { 0, (MCF_MBAR+MCFUART_BASE2), IRQBASE+1, ASYNC_BOOT_AUTOCONF },  /* ttyS1 */
};


#define	NR_PORTS	(sizeof(mcfrs_table) / sizeof(struct mcf_serial))

static struct tty_struct	*mcfrs_serial_table[NR_PORTS];
static struct termios		*mcfrs_serial_termios[NR_PORTS];
static struct termios		*mcfrs_serial_termios_locked[NR_PORTS];

/*
 * This is used to figure out the divisor speeds and the timeouts.
 */
static int mcfrs_baud_table[] = {
	0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
	9600, 19200, 38400, 57600, 115200, 230400, 460800, 0
};
#define MCFRS_BAUD_TABLE_SIZE \
			(sizeof(mcfrs_baud_table)/sizeof(mcfrs_baud_table[0]))


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

#ifdef CONFIG_MAGIC_SYSRQ
/*
 *	Magic system request keys. Used for debugging...
 */
extern int	magic_sysrq_key(int ch);
#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 mcfrs_tmp_buf[4096]; /* This is cheating */
#if LINUX_VERSION_CODE < 0x020100
static struct semaphore mcfrs_tmp_buf_sem = MUTEX;
#else
static DECLARE_MUTEX(mcfrs_tmp_buf_sem);
#endif

/*
 *	Forware declarations...
 */
static void	mcfrs_change_speed(struct mcf_serial *info);


static inline int serial_paranoia_check(struct mcf_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 mcf_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;
}

/*
 *	Sets or clears DTR and RTS on the requested line.
 */
static void mcfrs_setsignals(struct mcf_serial *info, int dtr, int rts)
{
	volatile unsigned char	*uartp;
	unsigned long		flags;
	
#if 0
	printk("%s(%d): mcfrs_setsignals(info=%x,dtr=%d,rts=%d)\n",
		__FILE__, __LINE__, info, dtr, rts);
#endif

	save_flags(flags); cli();
	if (dtr >= 0) {
#ifdef MCFPP_DTR0
		if (info->line)
			mcf_setppdata(MCFPP_DTR1, (dtr ? 0 : MCFPP_DTR1));
		else
			mcf_setppdata(MCFPP_DTR0, (dtr ? 0 : MCFPP_DTR0));
#endif
	}
	if (rts >= 0) {
		uartp = (volatile unsigned char *) info->addr;
		if (rts) {
			info->sigs |= TIOCM_RTS;
			uartp[MCFUART_UOP1] = MCFUART_UOP_RTS;
		} else {
			info->sigs &= ~TIOCM_RTS;
			uartp[MCFUART_UOP0] = MCFUART_UOP_RTS;
		}
	}
	restore_flags(flags);
	return;
}

/*
 *	Gets values of serial signals.
 */
static int mcfrs_getsignals(struct mcf_serial *info)
{
	volatile unsigned char	*uartp;
	unsigned long		flags;
	int			sigs;
#if defined(CONFIG_NETtel) && defined(CONFIG_M5307)
	unsigned short		ppdata;
#endif

#if 0
	printk("%s(%d): mcfrs_getsignals(info=%x)\n", __FILE__, __LINE__);
#endif

	save_flags(flags); cli();
	uartp = (volatile unsigned char *) info->addr;
	sigs = (uartp[MCFUART_UIPR] & MCFUART_UIPR_CTS) ? 0 : TIOCM_CTS;
	sigs |= (info->sigs & TIOCM_RTS);

#ifdef MCFPP_DCD0
{
	unsigned int ppdata;
	ppdata = mcf_getppdata();
	if (info->line == 0) {
		sigs |= (ppdata & MCFPP_DCD0) ? 0 : TIOCM_CD;
		sigs |= (ppdata & MCFPP_DTR0) ? 0 : TIOCM_DTR;
	} else if (info->line == 1) {
		sigs |= (ppdata & MCFPP_DCD1) ? 0 : TIOCM_CD;
		sigs |= (ppdata & MCFPP_DTR1) ? 0 : TIOCM_DTR;
	}
}
#endif

	restore_flags(flags);
	return(sigs);
}

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

	if (serial_paranoia_check(info, tty->device, "mcfrs_stop"))
		return;
	
	save_flags(flags); cli();
	uartp = (volatile unsigned char *) info->addr;
	info->imr &= ~MCFUART_UIR_TXREADY;
	uartp[MCFUART_UIMR] = info->imr;
	restore_flags(flags);
}

static void mcfrs_start(struct tty_struct *tty)
{
	volatile unsigned char	*uartp;
	struct mcf_serial	*info = (struct mcf_serial *)tty->driver_data;
	unsigned long		flags;
	
	if (serial_paranoia_check(info, tty->device, "mcfrs_start"))
		return;

	save_flags(flags); cli();
	if (info->xmit_cnt && info->xmit_buf) {
		uartp = (volatile unsigned char *) info->addr;
		info->imr |= MCFUART_UIR_TXREADY;
		uartp[MCFUART_UIMR] = info->imr;
	}
	restore_flags(flags);
}

/*
 * ----------------------------------------------------------------------
 *
 * Here starts the interrupt handling routines.  All of the following
 * subroutines are declared as inline and are folded into
 * mcfrs_interrupt().  They were separated out for readability's sake.
 *
 * Note: mcfrs_interrupt() is a "fast" interrupt, which means that it
 * runs with interrupts turned off.  People who may want to modify
 * mcfrs_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 mcfrs_sched_event(struct mcf_serial *info, int event)
{
	info->event |= 1 << event;
	queue_task(&info->tqueue, &mcf_tq_serial);
	mark_bh(CM206_BH);
}

static _INLINE_ void receive_chars(struct mcf_serial *info, struct pt_regs *regs, unsigned short rx)
{
	volatile unsigned char	*uartp;
	struct tty_struct	*tty = info->tty;
	unsigned char		status, ch;

	if (!tty)
		return;

#if defined(CONFIG_LEDMAN)
	ledman_cmd(LEDMAN_CMD_SET, info->line ? LEDMAN_COM2_RX : LEDMAN_COM1_RX);
#endif

	uartp = (volatile unsigned char *) info->addr;

	while ((status = uartp[MCFUART_USR]) & MCFUART_USR_RXREADY) {

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

		ch = uartp[MCFUART_URB];
		info->stats.rx++;

#ifdef CONFIG_MAGIC_SYSRQ
		if (mcfrs_console_inited && (info->line == mcfrs_console_port)) {
			if (magic_sysrq_key(ch))
				continue;
		}
#endif

		tty->flip.count++;
		if (status & MCFUART_USR_RXERR)
			uartp[MCFUART_UCR] = MCFUART_UCR_CMDRESETERR;
		if (status & MCFUART_USR_RXBREAK) {
			info->stats.rxbreak++;
			*tty->flip.flag_buf_ptr++ = TTY_BREAK;
		} else if (status & MCFUART_USR_RXPARITY) {
			info->stats.rxparity++;
			*tty->flip.flag_buf_ptr++ = TTY_PARITY;
		} else if (status & MCFUART_USR_RXOVERRUN) {
			info->stats.rxoverrun++;
			*tty->flip.flag_buf_ptr++ = TTY_OVERRUN;
		} else if (status & MCFUART_USR_RXFRAMING) {
			info->stats.rxframing++;
			*tty->flip.flag_buf_ptr++ = TTY_FRAME;
		} else {
			*tty->flip.flag_buf_ptr++ = 0;
		}
		*tty->flip.char_buf_ptr++ = ch;
	}

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

static _INLINE_ void transmit_chars(struct mcf_serial *info)
{
	volatile unsigned char	*uartp;

#if defined(CONFIG_LEDMAN)
	ledman_cmd(LEDMAN_CMD_SET, info->line ? LEDMAN_COM2_TX : LEDMAN_COM1_TX);
#endif

	uartp = (volatile unsigned char *) info->addr;

	if (info->x_char) {
		/* Send special char - probably flow control */
		uartp[MCFUART_UTB] = info->x_char;
		info->x_char = 0;
		info->stats.tx++;
	}

	if ((info->xmit_cnt <= 0) || info->tty->stopped) {
		info->imr &= ~MCFUART_UIR_TXREADY;
		uartp[MCFUART_UIMR] = info->imr;
		return;
	}

	while (uartp[MCFUART_USR] & MCFUART_USR_TXREADY) {
		uartp[MCFUART_UTB] = info->xmit_buf[info->xmit_tail++];
		info->xmit_tail = info->xmit_tail & (SERIAL_XMIT_SIZE-1);
		info->stats.tx++;
		if (--info->xmit_cnt <= 0)
			break;
	}

	if (info->xmit_cnt < WAKEUP_CHARS)
		mcfrs_sched_event(info, RS_EVENT_WRITE_WAKEUP);
	return;
}

/*
 * This is the serial driver's generic interrupt routine
 */
void mcfrs_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
	struct mcf_serial	*info;
	unsigned char		isr;

	info = &mcfrs_table[(irq - IRQBASE)];
	isr = (((volatile unsigned char *)info->addr)[MCFUART_UISR]) & info->imr;

	if (isr & MCFUART_UIR_RXREADY)
		receive_chars(info, regs, isr);
	if (isr & MCFUART_UIR_TXREADY)
		transmit_chars(info);
#if 0
	if (isr & MCFUART_UIR_DELTABREAK) {
		printk("%s(%d): delta break!\n", __FILE__, __LINE__);
		receive_chars(info, regs, isr);
	}
#endif

	return;
}

/*
 * -------------------------------------------------------------------
 * 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
 * mcfrs_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 mcfrs_sched_event(), and they get done here.
 */
static void do_serial_bh(void)
{
	run_task_queue(&mcf_tq_serial);
}

static void do_softint(void *private_)
{
	struct mcf_serial	*info = (struct mcf_serial *) 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);
	}
}