amiserial.c

讲述linux的初始化过程

	 * If non-blocking mode is set, or the port is not enabled,
	 * then make the check up front and then exit.
	 */
	if ((filp->f_flags & O_NONBLOCK) ||
	    (tty->flags & (1 << TTY_IO_ERROR))) {
		if (info->flags & ASYNC_CALLOUT_ACTIVE)
			return -EBUSY;
		info->flags |= ASYNC_NORMAL_ACTIVE;
		return 0;
	}

	if (info->flags & ASYNC_CALLOUT_ACTIVE) {
		if (state->normal_termios.c_cflag & CLOCAL)
			do_clocal = 1;
	} else {
		if (tty->termios->c_cflag & CLOCAL)
			do_clocal = 1;
	}

	/*
	 * Block waiting for the carrier detect and the line to become
	 * free (i.e., not in use by the callout).  While we are in
	 * this loop, state->count is dropped by one, so that
	 * rs_close() knows when to free things.  We restore it upon
	 * exit, either normal or abnormal.
	 */
	retval = 0;
	add_wait_queue(&info->open_wait, &wait);
#ifdef SERIAL_DEBUG_OPEN
	printk("block_til_ready before block: ttys%d, count = %d\n",
	       state->line, state->count);
#endif
	save_flags(flags); cli();
	if (!tty_hung_up_p(filp)) {
		extra_count = 1;
		state->count--;
	}
	restore_flags(flags);
	info->blocked_open++;
	while (1) {
		save_flags(flags); cli();
		if (!(info->flags & ASYNC_CALLOUT_ACTIVE) &&
		    (tty->termios->c_cflag & CBAUD))
		        rtsdtr_ctrl(SER_DTR|SER_RTS);
		restore_flags(flags);
		set_current_state(TASK_INTERRUPTIBLE);
		if (tty_hung_up_p(filp) ||
		    !(info->flags & ASYNC_INITIALIZED)) {
#ifdef SERIAL_DO_RESTART
			if (info->flags & ASYNC_HUP_NOTIFY)
				retval = -EAGAIN;
			else
				retval = -ERESTARTSYS;
#else
			retval = -EAGAIN;
#endif
			break;
		}
		if (!(info->flags & ASYNC_CALLOUT_ACTIVE) &&
		    !(info->flags & ASYNC_CLOSING) &&
		    (do_clocal || (!(ciab.pra & SER_DCD)) ))
			break;
		if (signal_pending(current)) {
			retval = -ERESTARTSYS;
			break;
		}
#ifdef SERIAL_DEBUG_OPEN
		printk("block_til_ready blocking: ttys%d, count = %d\n",
		       info->line, state->count);
#endif
		schedule();
	}
	current->state = TASK_RUNNING;
	remove_wait_queue(&info->open_wait, &wait);
	if (extra_count)
		state->count++;
	info->blocked_open--;
#ifdef SERIAL_DEBUG_OPEN
	printk("block_til_ready after blocking: ttys%d, count = %d\n",
	       info->line, state->count);
#endif
	if (retval)
		return retval;
	info->flags |= ASYNC_NORMAL_ACTIVE;
	return 0;
}

static int get_async_struct(int line, struct async_struct **ret_info)
{
	struct async_struct *info;
	struct serial_state *sstate;

	sstate = rs_table + line;
	sstate->count++;
	if (sstate->info) {
		*ret_info = sstate->info;
		return 0;
	}
	info = kmalloc(sizeof(struct async_struct), GFP_KERNEL);
	if (!info) {
		sstate->count--;
		return -ENOMEM;
	}
	memset(info, 0, sizeof(struct async_struct));
#ifdef DECLARE_WAITQUEUE
	init_waitqueue_head(&info->open_wait);
	init_waitqueue_head(&info->close_wait);
	init_waitqueue_head(&info->delta_msr_wait);
#endif
	info->magic = SERIAL_MAGIC;
	info->port = sstate->port;
	info->flags = sstate->flags;
	info->xmit_fifo_size = sstate->xmit_fifo_size;
	info->line = line;
	info->tqueue.routine = do_softint;
	info->tqueue.data = info;
	info->state = sstate;
	if (sstate->info) {
		kfree(info);
		*ret_info = sstate->info;
		return 0;
	}
	*ret_info = sstate->info = info;
	return 0;
}

/*
 * This routine is called whenever a serial port is opened.  It
 * enables interrupts for a serial port, linking in its async structure into
 * the IRQ chain.   It also performs the serial-specific
 * initialization for the tty structure.
 */
static int rs_open(struct tty_struct *tty, struct file * filp)
{
	struct async_struct	*info;
	int 			retval, line;
	unsigned long		page;

	MOD_INC_USE_COUNT;
	line = MINOR(tty->device) - tty->driver.minor_start;
	if ((line < 0) || (line >= NR_PORTS)) {
		MOD_DEC_USE_COUNT;
		return -ENODEV;
	}
	retval = get_async_struct(line, &info);
	if (retval) {
		MOD_DEC_USE_COUNT;
		return retval;
	}
	tty->driver_data = info;
	info->tty = tty;
	if (serial_paranoia_check(info, tty->device, "rs_open"))
		return -ENODEV;

#ifdef SERIAL_DEBUG_OPEN
	printk("rs_open %s%d, count = %d\n", tty->driver.name, info->line,
	       info->state->count);
#endif
	info->tty->low_latency = (info->flags & ASYNC_LOW_LATENCY) ? 1 : 0;

	if (!tmp_buf) {
		page = get_free_page(GFP_KERNEL);
		if (!page) {
			return -ENOMEM;
		}
		if (tmp_buf)
			free_page(page);
		else
			tmp_buf = (unsigned char *) page;
	}

	/*
	 * If the port is the middle of closing, bail out now
	 */
	if (tty_hung_up_p(filp) ||
	    (info->flags & ASYNC_CLOSING)) {
		if (info->flags & ASYNC_CLOSING)
			interruptible_sleep_on(&info->close_wait);
#ifdef SERIAL_DO_RESTART
		return ((info->flags & ASYNC_HUP_NOTIFY) ?
			-EAGAIN : -ERESTARTSYS);
#else
		return -EAGAIN;
#endif
	}

	/*
	 * Start up serial port
	 */
	retval = startup(info);
	if (retval) {
		return retval;
	}

	retval = block_til_ready(tty, filp, info);
	if (retval) {
#ifdef SERIAL_DEBUG_OPEN
		printk("rs_open returning after block_til_ready with %d\n",
		       retval);
#endif
		return retval;
	}

	if ((info->state->count == 1) &&
	    (info->flags & ASYNC_SPLIT_TERMIOS)) {
		if (tty->driver.subtype == SERIAL_TYPE_NORMAL)
			*tty->termios = info->state->normal_termios;
		else 
			*tty->termios = info->state->callout_termios;
		change_speed(info, 0);
	}
	info->session = current->session;
	info->pgrp = current->pgrp;

#ifdef SERIAL_DEBUG_OPEN
	printk("rs_open ttys%d successful...", info->line);
#endif
	return 0;
}

/*
 * /proc fs routines....
 */

static inline int line_info(char *buf, struct serial_state *state)
{
	struct async_struct *info = state->info, scr_info;
	char	stat_buf[30], control, status;
	int	ret;
	unsigned long flags;

	ret = sprintf(buf, "%d: uart:amiga_builtin",state->line);

	/*
	 * Figure out the current RS-232 lines
	 */
	if (!info) {
		info = &scr_info;	/* This is just for serial_{in,out} */

		info->magic = SERIAL_MAGIC;
		info->flags = state->flags;
		info->quot = 0;
		info->tty = 0;
	}
	save_flags(flags); cli();
	status = ciab.pra;
	control = info ? info->MCR : status;
	restore_flags(flags); 

	stat_buf[0] = 0;
	stat_buf[1] = 0;
	if(!(control & SER_RTS))
		strcat(stat_buf, "|RTS");
	if(!(status & SER_CTS))
		strcat(stat_buf, "|CTS");
	if(!(control & SER_DTR))
		strcat(stat_buf, "|DTR");
	if(!(status & SER_DSR))
		strcat(stat_buf, "|DSR");
	if(!(status & SER_DCD))
		strcat(stat_buf, "|CD");

	if (info->quot) {
		ret += sprintf(buf+ret, " baud:%d",
			       state->baud_base / info->quot);
	}

	ret += sprintf(buf+ret, " tx:%d rx:%d",
		      state->icount.tx, state->icount.rx);

	if (state->icount.frame)
		ret += sprintf(buf+ret, " fe:%d", state->icount.frame);

	if (state->icount.parity)
		ret += sprintf(buf+ret, " pe:%d", state->icount.parity);

	if (state->icount.brk)
		ret += sprintf(buf+ret, " brk:%d", state->icount.brk);

	if (state->icount.overrun)
		ret += sprintf(buf+ret, " oe:%d", state->icount.overrun);

	/*
	 * Last thing is the RS-232 status lines
	 */
	ret += sprintf(buf+ret, " %s\n", stat_buf+1);
	return ret;
}

int rs_read_proc(char *page, char **start, off_t off, int count,
		 int *eof, void *data)
{
	int len = 0, l;
	off_t	begin = 0;

	len += sprintf(page, "serinfo:1.0 driver:%s\n", serial_version);
	l = line_info(page + len, &rs_table[0]);
	len += l;
	if (len+begin > off+count)
	  goto done;
	if (len+begin < off) {
	  begin += len;
	  len = 0;
	}
	*eof = 1;
done:
	if (off >= len+begin)
		return 0;
	*start = page + (off-begin);
	return ((count < begin+len-off) ? count : begin+len-off);
}

/*
 * ---------------------------------------------------------------------
 * rs_init() and friends
 *
 * rs_init() is called at boot-time to initialize the serial driver.
 * ---------------------------------------------------------------------
 */

/*
 * This routine prints out the appropriate serial driver version
 * number, and identifies which options were configured into this
 * driver.
 */
static _INLINE_ void show_serial_version(void)
{
 	printk(KERN_INFO "%s version %s\n", serial_name, serial_version);
}


int register_serial(struct serial_struct *req);
void unregister_serial(int line);


/*
 * The serial driver boot-time initialization code!
 */
static int __init rs_init(void)
{
	unsigned long flags;
	struct serial_state * state;

	if (!MACH_IS_AMIGA || !AMIGAHW_PRESENT(AMI_SERIAL))
		return -ENODEV;

	/*
	 *  We request SERDAT and SERPER only, because the serial registers are
	 *  too spreaded over the custom register space
	 */
	if (!request_mem_region(CUSTOM_PHYSADDR+0x30, 4, "amiserial [Paula]"))
		return -EBUSY;

	init_bh(SERIAL_BH, do_serial_bh);

	IRQ_ports = NULL;

	show_serial_version();

	/* Initialize the tty_driver structure */

	memset(&serial_driver, 0, sizeof(struct tty_driver));
	serial_driver.magic = TTY_DRIVER_MAGIC;
	serial_driver.driver_name = "amiserial";
	serial_driver.name = "ttyS";
	serial_driver.major = TTY_MAJOR;
	serial_driver.minor_start = 64;
	serial_driver.num = 1;
	serial_driver.type = TTY_DRIVER_TYPE_SERIAL;
	serial_driver.subtype = SERIAL_TYPE_NORMAL;
	serial_driver.init_termios = tty_std_termios;
	serial_driver.init_termios.c_cflag =
		B9600 | CS8 | CREAD | HUPCL | CLOCAL;
	serial_driver.flags = TTY_DRIVER_REAL_RAW;
	serial_driver.refcount = &serial_refcount;
	serial_driver.table = serial_table;
	serial_driver.termios = serial_termios;
	serial_driver.termios_locked = serial_termios_locked;

	serial_driver.open = rs_open;
	serial_driver.close = rs_close;
	serial_driver.write = rs_write;
	serial_driver.put_char = rs_put_char;
	serial_driver.flush_chars = rs_flush_chars;
	serial_driver.write_room = rs_write_room;
	serial_driver.chars_in_buffer = rs_chars_in_buffer;
	serial_driver.flush_buffer = rs_flush_buffer;
	serial_driver.ioctl = rs_ioctl;
	serial_driver.throttle = rs_throttle;
	serial_driver.unthrottle = rs_unthrottle;
	serial_driver.set_termios = rs_set_termios;
	serial_driver.stop = rs_stop;
	serial_driver.start = rs_start;
	serial_driver.hangup = rs_hangup;
	serial_driver.break_ctl = rs_break;
	serial_driver.send_xchar = rs_send_xchar;
	serial_driver.wait_until_sent = rs_wait_until_sent;
	serial_driver.read_proc = rs_read_proc;

	/*
	 * The callout device is just like normal device except for
	 * major number and the subtype code.
	 */
	callout_driver = serial_driver;
	callout_driver.name = "cua";
	callout_driver.major = TTYAUX_MAJOR;
	callout_driver.subtype = SERIAL_TYPE_CALLOUT;
	callout_driver.read_proc = 0;
	callout_driver.proc_entry = 0;

	if (tty_register_driver(&serial_driver))
		panic("Couldn't register serial driver\n");
	if (tty_register_driver(&callout_driver))
		panic("Couldn't register callout driver\n");

	state = rs_table;
	state->magic = SSTATE_MAGIC;
	state->port = (int)&custom.serdatr; /* Just to give it a value */
	state->line = 0;
	state->custom_divisor = 0;
	state->close_delay = 5*HZ/10;
	state->closing_wait = 30*HZ;
	state->callout_termios = callout_driver.init_termios;
	state->normal_termios = serial_driver.init_termios;
	state->icount.cts = state->icount.dsr = 
	  state->icount.rng = state->icount.dcd = 0;
	state->icount.rx = state->icount.tx = 0;
	state->icount.frame = state->icount.parity = 0;
	state->icount.overrun = state->icount.brk = 0;
	/*
	if(state->port && check_region(state->port,REGION_LENGTH(state)))
	  continue;
	*/

	printk(KERN_INFO "ttyS%02d is the amiga builtin serial port\n",
		       state->line);

	/* Hardware set up */

	state->baud_base = amiga_colorclock;
	state->xmit_fifo_size = 1;

	save_flags (flags);
	cli();

	/* set ISRs, and then disable the rx interrupts */
	request_irq(IRQ_AMIGA_TBE, ser_tx_int, 0, "serial TX", state);
	request_irq(IRQ_AMIGA_RBF, ser_rx_int, SA_INTERRUPT, "serial RX", state);

	/* turn off Rx and Tx interrupts */
	custom.intena = IF_RBF | IF_TBE;
	mb();

	/* clear any pending interrupt */
	custom.intreq = IF_RBF | IF_TBE;
	mb();

	restore_flags (flags);

	/*
	 * set the appropriate directions for the modem control flags,
	 * and clear RTS and DTR
	 */
	ciab.ddra |= (SER_DTR | SER_RTS);   /* outputs */
	ciab.ddra &= ~(SER_DCD | SER_CTS | SER_DSR);  /* inputs */

	return 0;
}

static __exit void rs_exit(void) 
{
	unsigned long flags;
	int e1, e2;
	struct async_struct *info;

	/* printk("Unloading %s: version %s\n", serial_name, serial_version); */
	save_flags(flags);
	cli();
        remove_bh(SERIAL_BH);
	if ((e1 = tty_unregister_driver(&serial_driver)))
		printk("SERIAL: failed to unregister serial driver (%d)\n",
		       e1);
	if ((e2 = tty_unregister_driver(&callout_driver)))
		printk("SERIAL: failed to unregister callout driver (%d)\n", 
		       e2);
	restore_flags(flags);

	info = rs_table[0].info;
	if (info) {
	  rs_table[0].info = NULL;
	  kfree(info);
	}

	if (tmp_buf) {
		free_page((unsigned long) tmp_buf);
		tmp_buf = NULL;
	}

	release_mem_region(CUSTOM_PHYSADDR+0x30, 4);
}

module_init(rs_init)
module_exit(rs_exit)


/*
 * ------------------------------------------------------------
 * Serial console driver
 * ------------------------------------------------------------
 */
#ifdef CONFIG_SERIAL_CONSOLE

static void amiga_serial_putc(char c)
{
	custom.serdat = (unsigned char)c | 0x100;
	while (!(custom.serdatr & 0x2000))
		barrier();
}

/*
 *	Print a string to the serial port trying not to disturb
 *	any possible real use of the port...
 *
 *	The console_lock must be held when we get here.
 */
static void serial_console_write(struct console *co, const char *s,
				unsigned count)
{
	unsigned short intena = custom.intenar;

	custom.intena = IF_TBE;

	while (count--) {
		if (*s == '\n')
			amiga_serial_putc('\r');
		amiga_serial_putc(*s++);
	}

	custom.intena = IF_SETCLR | (intena & IF_TBE);
}

/*
 *	Receive character from the serial port
 */
static int serial_console_wait_key(struct console *co)
{
	unsigned short intena = custom.intenar;
	int ch;

	custom.intena = IF_RBF;

	while (!(custom.intreqr & IF_RBF))
		barrier();
	ch = custom.serdatr & 0xff;
	custom.intreq = IF_RBF;

	custom.intena = IF_SETCLR | (intena & IF_RBF);

	return ch;
}

static kdev_t serial_console_device(struct console *c)
{
	return MKDEV(TTY_MAJOR, 64);
}

static struct console sercons = {
	"ttyS",
	serial_console_write,
	NULL,
	serial_console_device,
	serial_console_wait_key,
	NULL,
	NULL,
	CON_PRINTBUFFER,
	-1,
	0,
	NULL
};

/*
 *	Register console.
 */
void __init serial_console_init(void)
{
	register_console(&sercons);
}
#endif