serial_44b0.c

serial port driver in linux

	new_port = new_serial.port;
	if (HIGH_BITS_OFFSET)
		new_port += (unsigned long) new_serial.port_high << HIGH_BITS_OFFSET;

	change_irq = new_serial.irq != state->irq;
	change_port = (new_port != ((int) state->port)) ||
		(new_serial.hub6 != state->hub6);
  
	if (!capable(CAP_SYS_ADMIN)) {
		if (change_irq || change_port ||
		    (new_serial.baud_base != state->baud_base) ||
		    (new_serial.type != state->type) ||
		    (new_serial.close_delay != state->close_delay) ||
		    (new_serial.xmit_fifo_size != state->xmit_fifo_size) ||
		    ((new_serial.flags & ~ASYNC_USR_MASK) !=
		     (state->flags & ~ASYNC_USR_MASK)))
			return -EPERM;
		state->flags = ((state->flags & ~ASYNC_USR_MASK) |
			       (new_serial.flags & ASYNC_USR_MASK));
		info->flags = ((info->flags & ~ASYNC_USR_MASK) |
			       (new_serial.flags & ASYNC_USR_MASK));
		state->custom_divisor = new_serial.custom_divisor;
		goto check_and_exit;
	}

	new_serial.irq = irq_cannonicalize(new_serial.irq);

	if ((new_serial.irq >= NR_IRQS) || (new_serial.irq < 0) || 
	    (new_serial.baud_base < 9600)|| (new_serial.type < PORT_UNKNOWN) ||
	    (new_serial.type > PORT_MAX) || (new_serial.type == PORT_CIRRUS) ||
	    (new_serial.type == PORT_STARTECH)) {
		return -EINVAL;
	}

	if ((new_serial.type != state->type) ||
	    (new_serial.xmit_fifo_size <= 0))
		new_serial.xmit_fifo_size =
			uart_config[new_serial.type].dfl_xmit_fifo_size;

	// Make sure address is not already in use
	if (new_serial.type) {
		for (i = 0 ; i < NR_PORTS; i++)
			if ((state != &rs_table[i]) &&
			    (rs_table[i].port == new_port) &&
			    rs_table[i].type)
				return -EADDRINUSE;
	}

	if ((change_port || change_irq) && (state->count > 1))
		return -EBUSY;

	//
	// OK, past this point, all the error checking has been done.
	// At this point, we start making changes.....
	//

	state->baud_base = new_serial.baud_base;
	state->flags = ((state->flags & ~ASYNC_FLAGS) |
			(new_serial.flags & ASYNC_FLAGS));
	info->flags = ((state->flags & ~ASYNC_INTERNAL_FLAGS) |
		       (info->flags & ASYNC_INTERNAL_FLAGS));
	state->custom_divisor = new_serial.custom_divisor;
	state->close_delay = new_serial.close_delay * HZ/100;
	state->closing_wait = new_serial.closing_wait * HZ/100;
#if (LINUX_VERSION_CODE > 0x20100)
	info->tty->low_latency = (info->flags & ASYNC_LOW_LATENCY) ? 1 : 0;
#endif
	info->xmit_fifo_size = state->xmit_fifo_size =
		new_serial.xmit_fifo_size;

	if ((state->type != PORT_UNKNOWN) && state->port) {
		release_region(state->port,8);
	}
	state->type = new_serial.type;
	if (change_port || change_irq) {
		//
		// We need to shutdown the serial port at the old
		// port/irq combination.
		//
		shutdown(info);
		state->irq = new_serial.irq;
		info->port = state->port = new_port;
		info->hub6 = state->hub6 = new_serial.hub6;
		if (info->hub6)
			info->io_type = state->io_type = SERIAL_IO_HUB6;
		else if (info->io_type == SERIAL_IO_HUB6)
			info->io_type = state->io_type = SERIAL_IO_PORT;
	}
	if ((state->type != PORT_UNKNOWN) && state->port) {
			request_region(state->port,8,"serial(set)");
	}

	
check_and_exit:
	if (!state->port || !state->type)
		return 0;
	if (info->flags & ASYNC_INITIALIZED) {
		if (((old_state.flags & ASYNC_SPD_MASK) !=
		     (state->flags & ASYNC_SPD_MASK)) ||
		    (old_state.custom_divisor != state->custom_divisor)) {
#if (LINUX_VERSION_CODE >= 131394) // Linux 2.1.66
			if ((state->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
				info->tty->alt_speed = 57600;
			if ((state->flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
				info->tty->alt_speed = 115200;
			if ((state->flags & ASYNC_SPD_MASK) == ASYNC_SPD_SHI)
				info->tty->alt_speed = 230400;
			if ((state->flags & ASYNC_SPD_MASK) == ASYNC_SPD_WARP)
				info->tty->alt_speed = 460800;
#endif
			change_speed(info, 0);
		}
	} else
		retval = startup(info);
	return retval;
}


/*
 * get_lsr_info - get line status register info
 *
 * Purpose: Let user call ioctl() to get info when the UART physically
 * 	    is emptied.  On bus types like RS485, the transmitter must
 * 	    release the bus after transmitting. This must be done when
 * 	    the transmit shift register is empty, not be done when the
 * 	    transmit holding register is empty.  This functionality
 * 	    allows an RS485 driver to be written in user space. 
 */
static int get_lsr_info(struct async_struct * info, unsigned int *value)
{
	unsigned char status;
	unsigned int result;
	unsigned long flags;

	save_flags(flags); cli();
	if(info->line==0||info->line==1)
	    status = serial_in(info, UART_LSR);
	/*else                                      */
	    /*status = serial_in(info, EX_UART_LSR);*/
	    
	restore_flags(flags);
	result = ((status & UART_LSR_TEMT) ? TIOCSER_TEMT : 0);

	//
	// If we're about to load something into the transmit
	// register, we'll pretend the transmitter isn't empty to
	// avoid a race condition (depending on when the transmit
	// interrupt happens).
	//
	if (info->x_char || 
	    ((CIRC_CNT(info->xmit.head, info->xmit.tail,
		       SERIAL_XMIT_SIZE) > 0) &&
	     !info->tty->stopped && !info->tty->hw_stopped))
		result &= TIOCSER_TEMT;

	if (copy_to_user(value, &result, sizeof(int)))
		return -EFAULT;
	return 0;
}


static int do_autoconfig(struct async_struct * info)
{
	int irq, retval;
	
	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;
	
	if (info->state->count > 1)
		return -EBUSY;
	
	shutdown(info);

	autoconfig(info->state);
	if ((info->state->flags & ASYNC_AUTO_IRQ) &&
	    (info->state->port != 0) &&
	    (info->state->type != PORT_UNKNOWN)) {
		irq = detect_uart_irq(info->state);
		if (irq > 0)
			info->state->irq = irq;
	}

	retval = startup(info);
	if (retval)
		return retval;
	return 0;
}

/*
 * rs_break() --- routine which turns the break handling on or off
 */
#if (LINUX_VERSION_CODE < 131394) /* Linux 2.1.66 */

#else
static void rs_break(struct tty_struct *tty, int break_state)
{
	struct async_struct * info = (struct async_struct *)tty->driver_data;
	unsigned long flags, tmp;
	
	if (serial_paranoia_check(info, tty->device, "rs_break"))
		return;

	if (!CONFIGURED_SERIAL_PORT(info))
		return;
	save_flags(flags); cli();
/*
	if (break_state == -1)
		info->LCR |= UART_LCR_SBC;
	else
		info->LCR &= ~UART_LCR_SBC;
	serial_out(info, UART_LCR, info->LCR);
*/
	if(info->line==0||info->line==1)
		tmp = serial_in(info, UART_GCR);
	/*else                                      */
		/*tmp = serial_in(info,EX_UART_GCR);*/
	if (break_state == -1)
		tmp |= UART_LCR_SBC;
	else
		tmp &= ~UART_LCR_SBC;
	if(info->line==0||info->line==1)
		serial_out(info, UART_GCR, tmp);
	restore_flags(flags);
}
#endif


static int rs_ioctl(struct tty_struct *tty, struct file * file,
		    unsigned int cmd, unsigned long arg)
{
	struct async_struct * info = (struct async_struct *)tty->driver_data;
	struct async_icount cprev, cnow;	// kernel counter temps
	struct serial_icounter_struct icount;
	unsigned long flags;
#if (LINUX_VERSION_CODE < 131394) // Linux 2.1.66
	int retval, tmp;
#endif
	
	if (serial_paranoia_check(info, tty->device, "rs_ioctl"))
		return -ENODEV;

	if ((cmd != TIOCGSERIAL) && (cmd != TIOCSSERIAL) &&
	    (cmd != TIOCSERCONFIG) && (cmd != TIOCSERGSTRUCT) &&
	    (cmd != TIOCMIWAIT) && (cmd != TIOCGICOUNT)) {
		if (tty->flags & (1 << TTY_IO_ERROR))
		    return -EIO;
	}
	
	switch (cmd) {
#if (LINUX_VERSION_CODE < 131394) // Linux 2.1.66
		case TCSBRK:	// SVID version: non-zero arg --> no break
			retval = tty_check_change(tty);
			if (retval)
				return retval;
			tty_wait_until_sent(tty, 0);
			if (signal_pending(current))
				return -EINTR;
			if (!arg) {
				send_break(info, HZ/4);	// 1/4 second
				if (signal_pending(current))
					return -EINTR;
			}
			return 0;
		case TCSBRKP:	// support for POSIX tcsendbreak()
			retval = tty_check_change(tty);
			if (retval)
				return retval;
			tty_wait_until_sent(tty, 0);
			if (signal_pending(current))
				return -EINTR;
			send_break(info, arg ? arg*(HZ/10) : HZ/4);
			if (signal_pending(current))
				return -EINTR;
			return 0;
		case TIOCGSOFTCAR:
			tmp = C_CLOCAL(tty) ? 1 : 0;
			if (copy_to_user((void *)arg, &tmp, sizeof(int)))
				return -EFAULT;
			return 0;
		case TIOCSSOFTCAR:
			if (copy_from_user(&tmp, (void *)arg, sizeof(int)))
				return -EFAULT;

			tty->termios->c_cflag =
				((tty->termios->c_cflag & ~CLOCAL) |
				 (tmp ? CLOCAL : 0));
			return 0;
#endif

		case TIOCGSERIAL:
			return get_serial_info(info,
					       (struct serial_struct *) arg);
		case TIOCSSERIAL:
			return set_serial_info(info,
					       (struct serial_struct *) arg);
		case TIOCSERCONFIG:
			return do_autoconfig(info);

		case TIOCSERGETLSR: // Get line status register
			return get_lsr_info(info, (unsigned int *) arg);

		case TIOCSERGSTRUCT:
			if (copy_to_user((struct async_struct *) arg,
					 info, sizeof(struct async_struct)))
				return -EFAULT;
			return 0;
				
			
		//
		// Wait for any of the 4 modem inputs (DCD,RI,DSR,CTS) to change
		// - mask passed in arg for lines of interest
 		//   (use |'ed TIOCM_RNG/DSR/CD/CTS for masking)
		// Caller should use TIOCGICOUNT to see which one it was
		//
		case TIOCMIWAIT:
			save_flags(flags); cli();
			// note the counters on entry
			cprev = info->state->icount;
			restore_flags(flags);
			// Force modem status interrupts on
			while (1) {
				interruptible_sleep_on(&info->delta_msr_wait);
				// see if a signal did it
				if (signal_pending(current))
					return -ERESTARTSYS;
				save_flags(flags); cli();
				cnow = info->state->icount; // atomic copy
				restore_flags(flags);
				if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr && 
				    cnow.dcd == cprev.dcd && cnow.cts == cprev.cts)
					return -EIO; // no change => error
				if ( ((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
				     ((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
				     ((arg & TIOCM_CD)  && (cnow.dcd != cprev.dcd)) ||
				     ((arg & TIOCM_CTS) && (cnow.cts != cprev.cts)) ) {
					return 0;
				}
				cprev = cnow;
			}
			// NOTREACHED

		// 
		// Get counter of input serial line interrupts (DCD,RI,DSR,CTS)
		// Return: write counters to the user passed counter struct
		// NB: both 1->0 and 0->1 transitions are counted except for
		//     RI where only 0->1 is counted.
		//
		case TIOCGICOUNT:
			save_flags(flags); cli();
			cnow = info->state->icount;
			restore_flags(flags);
			icount.cts = cnow.cts;
			icount.dsr = cnow.dsr;
			icount.rng = cnow.rng;
			icount.dcd = cnow.dcd;
			icount.rx = cnow.rx;
			icount.tx = cnow.tx;
			icount.frame = cnow.frame;
			icount.overrun = cnow.overrun;
			icount.parity = cnow.parity;
			icount.brk = cnow.brk;
			icount.buf_overrun = cnow.buf_overrun;
			
			if (copy_to_user((void *)arg, &icount, sizeof(icount)))
				return -EFAULT;
			return 0;
		case TIOCSERGWILD:
		case TIOCSERSWILD:
			// "setserial -W" is called in Debian boot
			printk ("TIOCSER?WILD ioctl obsolete, ignored.\n");
			return 0;

		default:
			return -ENOIOCTLCMD;
		}
	return 0;
}

static void rs_set_termios(struct tty_struct *tty, struct termios *old_termios)
{
	struct async_struct *info = (struct async_struct *)tty->driver_data;
//	unsigned long flags;
	unsigned int cflag = tty->termios->c_cflag;
	
	if (   (cflag == old_termios->c_cflag)
	    && (   RELEVANT_IFLAG(tty->termios->c_iflag) 
		== RELEVANT_IFLAG(old_termios->c_iflag)))
	  return;
	change_speed(info, old_termios);

	// Handle turning off CRTSCTS
	if ((old_termios->c_cflag & CRTSCTS) &&
	    !(tty->termios->c_cflag & CRTSCTS)) {
		tty->hw_stopped = 0;
		rs_start(tty);
	}
}

/*
 * ------------------------------------------------------------
 * rs_close()
 * 
 * This routine is called when the serial port gets closed.  First, we
 * wait for the last remaining data to be sent.  Then, we unlink its
 * async structure from the interrupt chain if necessary, and we free
 * that IRQ if nothing is left in the chain.
 * ------------------------------------------------------------
 */
static void rs_close(struct tty_struct *tty, struct file * filp)
{
	struct async_struct * info = (struct async_struct *)tty->driver_data;
	struct serial_state *state;
	unsigned long flags;

	if (!info || serial_paranoia_check(info, tty->device, "rs_close"))
		return;

	state = info->state;
	
	save_flags(flags); cli();
	
	if (tty_hung_up_p(filp)) {
		DBG_CNT("before DEC-hung");
		MOD_DEC_USE_COUNT;
		restore_flags(flags);
		return;
	}
	
#ifdef SERIAL_DEBUG_OPEN
	printk("rs_close ttys%d, count = %d\n", info->line, state->count);
#endif
	if ((tty->count == 1) && (state->count != 1)) {
		//
		// Uh, oh.  tty->count is 1, which means that the tty
		// structure will be freed.  state->count should always
		// be one in these conditions.  If it's greater than
		// one, we've got real problems, since it means the
		// serial port won't be shutdown.
		//
		printk("rs_close: bad serial port count; tty->count is 1, "
		       "state->count is %d\n", state->count);