/*
   *   serial.c

   *   Copyright (c) by Jaroslav Kysela <perex@perex.cz>,

   *                    Isaku Yamahata <yamahata@private.email.ne.jp>,
   *		      George Hansper <ghansper@apana.org.au>,
   *		      Hannu Savolainen
   *
   *   This code is based on the code from ALSA 0.5.9, but heavily rewritten.
   *
   *   This program is free software; you can redistribute it and/or modify
   *   it under the terms of the GNU General Public License as published by
   *   the Free Software Foundation; either version 2 of the License, or
   *   (at your option) any later version.
   *
   *   This program is distributed in the hope that it will be useful,
   *   but WITHOUT ANY WARRANTY; without even the implied warranty of
   *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *   GNU General Public License for more details.
   *
   *   You should have received a copy of the GNU General Public License
   *   along with this program; if not, write to the Free Software
   *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
   *
   * Sat Mar 31 17:27:57 PST 2001 tim.mann@compaq.com 
   *      Added support for the Midiator MS-124T and for the MS-124W in
   *      Single Addressed (S/A) or Multiple Burst (M/B) mode, with
   *      power derived either parasitically from the serial port or
   *      from a separate power supply.
   *
   *      More documentation can be found in serial-u16550.txt.
   */

  #include <linux/init.h>
  #include <linux/interrupt.h>

  #include <linux/err.h>
  #include <linux/platform_device.h>

  #include <linux/slab.h>
  #include <linux/ioport.h>

  #include <linux/module.h>

  #include <sound/core.h>
  #include <sound/rawmidi.h>
  #include <sound/initval.h>
  
  #include <linux/serial_reg.h>

  #include <linux/jiffies.h>

  
  #include <asm/io.h>
  
  MODULE_DESCRIPTION("MIDI serial u16550");
  MODULE_LICENSE("GPL");
  MODULE_SUPPORTED_DEVICE("{{ALSA, MIDI serial u16550}}");
  
  #define SNDRV_SERIAL_SOUNDCANVAS 0 /* Roland Soundcanvas; F5 NN selects part */
  #define SNDRV_SERIAL_MS124T 1      /* Midiator MS-124T */
  #define SNDRV_SERIAL_MS124W_SA 2   /* Midiator MS-124W in S/A mode */
  #define SNDRV_SERIAL_MS124W_MB 3   /* Midiator MS-124W in M/B mode */
  #define SNDRV_SERIAL_GENERIC 4     /* Generic Interface */
  #define SNDRV_SERIAL_MAX_ADAPTOR SNDRV_SERIAL_GENERIC
  static char *adaptor_names[] = {
  	"Soundcanvas",
          "MS-124T",
  	"MS-124W S/A",
  	"MS-124W M/B",
  	"Generic"
  };
  
  #define SNDRV_SERIAL_NORMALBUFF 0 /* Normal blocking buffer operation */
  #define SNDRV_SERIAL_DROPBUFF   1 /* Non-blocking discard operation */
  
  static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;	/* Index 0-MAX */
  static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;	/* ID for this card */

  static bool enable[SNDRV_CARDS] = SNDRV_DEFAULT_ENABLE; /* Enable this card */

  static long port[SNDRV_CARDS] = SNDRV_DEFAULT_PORT; /* 0x3f8,0x2f8,0x3e8,0x2e8 */
  static int irq[SNDRV_CARDS] = SNDRV_DEFAULT_IRQ; 	/* 3,4,5,7,9,10,11,14,15 */
  static int speed[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 38400}; /* 9600,19200,38400,57600,115200 */
  static int base[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 115200}; /* baud base */
  static int outs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 1};	 /* 1 to 16 */
  static int ins[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 1};	/* 1 to 16 */
  static int adaptor[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = SNDRV_SERIAL_SOUNDCANVAS};

  static bool droponfull[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS -1)] = SNDRV_SERIAL_NORMALBUFF };

  
  module_param_array(index, int, NULL, 0444);
  MODULE_PARM_DESC(index, "Index value for Serial MIDI.");
  module_param_array(id, charp, NULL, 0444);
  MODULE_PARM_DESC(id, "ID string for Serial MIDI.");
  module_param_array(enable, bool, NULL, 0444);
  MODULE_PARM_DESC(enable, "Enable UART16550A chip.");
  module_param_array(port, long, NULL, 0444);
  MODULE_PARM_DESC(port, "Port # for UART16550A chip.");
  module_param_array(irq, int, NULL, 0444);
  MODULE_PARM_DESC(irq, "IRQ # for UART16550A chip.");
  module_param_array(speed, int, NULL, 0444);
  MODULE_PARM_DESC(speed, "Speed in bauds.");
  module_param_array(base, int, NULL, 0444);
  MODULE_PARM_DESC(base, "Base for divisor in bauds.");
  module_param_array(outs, int, NULL, 0444);
  MODULE_PARM_DESC(outs, "Number of MIDI outputs.");
  module_param_array(ins, int, NULL, 0444);
  MODULE_PARM_DESC(ins, "Number of MIDI inputs.");
  module_param_array(droponfull, bool, NULL, 0444);
  MODULE_PARM_DESC(droponfull, "Flag to enable drop-on-full buffer mode");
  
  module_param_array(adaptor, int, NULL, 0444);
  MODULE_PARM_DESC(adaptor, "Type of adaptor.");
  
  /*#define SNDRV_SERIAL_MS124W_MB_NOCOMBO 1*/  /* Address outs as 0-3 instead of bitmap */
  
  #define SNDRV_SERIAL_MAX_OUTS	16		/* max 64, min 16 */
  #define SNDRV_SERIAL_MAX_INS	16		/* max 64, min 16 */
  
  #define TX_BUFF_SIZE		(1<<15)		/* Must be 2^n */
  #define TX_BUFF_MASK		(TX_BUFF_SIZE - 1)
  
  #define SERIAL_MODE_NOT_OPENED 		(0)
  #define SERIAL_MODE_INPUT_OPEN		(1 << 0)
  #define SERIAL_MODE_OUTPUT_OPEN		(1 << 1)
  #define SERIAL_MODE_INPUT_TRIGGERED	(1 << 2)
  #define SERIAL_MODE_OUTPUT_TRIGGERED	(1 << 3)

  struct snd_uart16550 {

  	struct snd_card *card;
  	struct snd_rawmidi *rmidi;
  	struct snd_rawmidi_substream *midi_output[SNDRV_SERIAL_MAX_OUTS];
  	struct snd_rawmidi_substream *midi_input[SNDRV_SERIAL_MAX_INS];

  	int filemode;		/* open status of file */

  
  	spinlock_t open_lock;
  
  	int irq;
  
  	unsigned long base;
  	struct resource *res_base;
  
  	unsigned int speed;
  	unsigned int speed_base;
  	unsigned char divisor;
  
  	unsigned char old_divisor_lsb;
  	unsigned char old_divisor_msb;
  	unsigned char old_line_ctrl_reg;

  	/* parameter for using of write loop */
  	short int fifo_limit;	/* used in uart16550 */
          short int fifo_count;	/* used in uart16550 */

  	/* type of adaptor */

  	int adaptor;

  	/* inputs */

  	int prev_in;
  	unsigned char rstatus;

  	/* outputs */

  	int prev_out;
  	unsigned char prev_status[SNDRV_SERIAL_MAX_OUTS];

  	/* write buffer and its writing/reading position */

  	unsigned char tx_buff[TX_BUFF_SIZE];
  	int buff_in_count;
          int buff_in;
          int buff_out;
          int drop_on_full;

  	/* wait timer */

  	unsigned int timer_running:1;
  	struct timer_list buffer_timer;

  };

  static struct platform_device *devices[SNDRV_CARDS];

  static inline void snd_uart16550_add_timer(struct snd_uart16550 *uart)

  {

  	if (!uart->timer_running) {

  		/* timer 38600bps * 10bit * 16byte */
  		uart->buffer_timer.expires = jiffies + (HZ+255)/256;
  		uart->timer_running = 1;
  		add_timer(&uart->buffer_timer);
  	}
  }

  static inline void snd_uart16550_del_timer(struct snd_uart16550 *uart)

  {
  	if (uart->timer_running) {
  		del_timer(&uart->buffer_timer);
  		uart->timer_running = 0;
  	}
  }
  
  /* This macro is only used in snd_uart16550_io_loop */

  static inline void snd_uart16550_buffer_output(struct snd_uart16550 *uart)

  {
  	unsigned short buff_out = uart->buff_out;

  	if (uart->buff_in_count > 0) {

  		outb(uart->tx_buff[buff_out], uart->base + UART_TX);
  		uart->fifo_count++;
  		buff_out++;
  		buff_out &= TX_BUFF_MASK;
  		uart->buff_out = buff_out;
  		uart->buff_in_count--;
  	}
  }
  
  /* This loop should be called with interrupts disabled
   * We don't want to interrupt this, 
   * as we're already handling an interrupt 
   */

  static void snd_uart16550_io_loop(struct snd_uart16550 * uart)

  {
  	unsigned char c, status;
  	int substream;
  
  	/* recall previous stream */
  	substream = uart->prev_in;
  
  	/* Read Loop */
  	while ((status = inb(uart->base + UART_LSR)) & UART_LSR_DR) {
  		/* while receive data ready */
  		c = inb(uart->base + UART_RX);
  
  		/* keep track of last status byte */

  		if (c & 0x80)

  			uart->rstatus = c;

  
  		/* handle stream switch */
  		if (uart->adaptor == SNDRV_SERIAL_GENERIC) {
  			if (uart->rstatus == 0xf5) {
  				if (c <= SNDRV_SERIAL_MAX_INS && c > 0)
  					substream = c - 1;
  				if (c != 0xf5)

  					/* prevent future bytes from being
  					   interpreted as streams */
  					uart->rstatus = 0;
  			} else if ((uart->filemode & SERIAL_MODE_INPUT_OPEN)
  				   && uart->midi_input[substream])
  				snd_rawmidi_receive(uart->midi_input[substream],
  						    &c, 1);
  		} else if ((uart->filemode & SERIAL_MODE_INPUT_OPEN) &&
  			   uart->midi_input[substream])

  			snd_rawmidi_receive(uart->midi_input[substream], &c, 1);

  
  		if (status & UART_LSR_OE)

  			snd_printk(KERN_WARNING
  				   "%s: Overrun on device at 0x%lx
  ",

  			       uart->rmidi->name, uart->base);
  	}
  
  	/* remember the last stream */
  	uart->prev_in = substream;
  
  	/* no need of check SERIAL_MODE_OUTPUT_OPEN because if not,
  	   buffer is never filled. */
  	/* Check write status */

  	if (status & UART_LSR_THRE)

  		uart->fifo_count = 0;

  	if (uart->adaptor == SNDRV_SERIAL_MS124W_SA
  	   || uart->adaptor == SNDRV_SERIAL_GENERIC) {
  		/* Can't use FIFO, must send only when CTS is true */
  		status = inb(uart->base + UART_MSR);

  		while (uart->fifo_count == 0 && (status & UART_MSR_CTS) &&
  		       uart->buff_in_count > 0) {

  		       snd_uart16550_buffer_output(uart);

  		       status = inb(uart->base + UART_MSR);

  		}
  	} else {
  		/* Write loop */

  		while (uart->fifo_count < uart->fifo_limit /* Can we write ? */

  		       && uart->buff_in_count > 0)	/* Do we want to? */
  			snd_uart16550_buffer_output(uart);
  	}
  	if (uart->irq < 0 && uart->buff_in_count > 0)
  		snd_uart16550_add_timer(uart);
  }
  
  /* NOTES ON SERVICING INTERUPTS
   * ---------------------------
   * After receiving a interrupt, it is important to indicate to the UART that
   * this has been done. 
   * For a Rx interrupt, this is done by reading the received byte.
   * For a Tx interrupt this is done by either:
   * a) Writing a byte
   * b) Reading the IIR
   * It is particularly important to read the IIR if a Tx interrupt is received
   * when there is no data in tx_buff[], as in this case there no other
   * indication that the interrupt has been serviced, and it remains outstanding
   * indefinitely. This has the curious side effect that and no further interrupts
   * will be generated from this device AT ALL!!.
   * It is also desirable to clear outstanding interrupts when the device is
   * opened/closed.
   *
   *
   * Note that some devices need OUT2 to be set before they will generate
   * interrupts at all. (Possibly tied to an internal pull-up on CTS?)
   */

  static irqreturn_t snd_uart16550_interrupt(int irq, void *dev_id)

  {

  	struct snd_uart16550 *uart;

  	uart = dev_id;

  	spin_lock(&uart->open_lock);
  	if (uart->filemode == SERIAL_MODE_NOT_OPENED) {
  		spin_unlock(&uart->open_lock);
  		return IRQ_NONE;
  	}

  	/* indicate to the UART that the interrupt has been serviced */
  	inb(uart->base + UART_IIR);

  	snd_uart16550_io_loop(uart);
  	spin_unlock(&uart->open_lock);
  	return IRQ_HANDLED;
  }
  
  /* When the polling mode, this function calls snd_uart16550_io_loop. */
  static void snd_uart16550_buffer_timer(unsigned long data)
  {
  	unsigned long flags;

  	struct snd_uart16550 *uart;

  	uart = (struct snd_uart16550 *)data;

  	spin_lock_irqsave(&uart->open_lock, flags);
  	snd_uart16550_del_timer(uart);
  	snd_uart16550_io_loop(uart);
  	spin_unlock_irqrestore(&uart->open_lock, flags);
  }
  
  /*
   *  this method probes, if an uart sits on given port
   *  return 0 if found
   *  return negative error if not found
   */

  static int __devinit snd_uart16550_detect(struct snd_uart16550 *uart)

  {
  	unsigned long io_base = uart->base;
  	int ok;
  	unsigned char c;
  
  	/* Do some vague tests for the presence of the uart */
  	if (io_base == 0 || io_base == SNDRV_AUTO_PORT) {
  		return -ENODEV;	/* Not configured */
  	}
  
  	uart->res_base = request_region(io_base, 8, "Serial MIDI");
  	if (uart->res_base == NULL) {
  		snd_printk(KERN_ERR "u16550: can't grab port 0x%lx
  ", io_base);
  		return -EBUSY;
  	}

  	/* uart detected unless one of the following tests should fail */
  	ok = 1;

  	/* 8 data-bits, 1 stop-bit, parity off, DLAB = 0 */
  	outb(UART_LCR_WLEN8, io_base + UART_LCR); /* Line Control Register */
  	c = inb(io_base + UART_IER);
  	/* The top four bits of the IER should always == 0 */
  	if ((c & 0xf0) != 0)
  		ok = 0;		/* failed */
  
  	outb(0xaa, io_base + UART_SCR);
  	/* Write arbitrary data into the scratch reg */
  	c = inb(io_base + UART_SCR);
  	/* If it comes back, it's OK */
  	if (c != 0xaa)
  		ok = 0;		/* failed */
  
  	outb(0x55, io_base + UART_SCR);
  	/* Write arbitrary data into the scratch reg */
  	c = inb(io_base + UART_SCR);
  	/* If it comes back, it's OK */
  	if (c != 0x55)
  		ok = 0;		/* failed */
  
  	return ok;
  }

  static void snd_uart16550_do_open(struct snd_uart16550 * uart)

  {
  	char byte;
  
  	/* Initialize basic variables */
  	uart->buff_in_count = 0;
  	uart->buff_in = 0;
  	uart->buff_out = 0;
  	uart->fifo_limit = 1;
  	uart->fifo_count = 0;
  	uart->timer_running = 0;
  
  	outb(UART_FCR_ENABLE_FIFO	/* Enable FIFO's (if available) */
  	     | UART_FCR_CLEAR_RCVR	/* Clear receiver FIFO */
  	     | UART_FCR_CLEAR_XMIT	/* Clear transmitter FIFO */
  	     | UART_FCR_TRIGGER_4	/* Set FIFO trigger at 4-bytes */
  	/* NOTE: interrupt generated after T=(time)4-bytes
  	 * if less than UART_FCR_TRIGGER bytes received
  	 */
  	     ,uart->base + UART_FCR);	/* FIFO Control Register */
  
  	if ((inb(uart->base + UART_IIR) & 0xf0) == 0xc0)
  		uart->fifo_limit = 16;
  	if (uart->divisor != 0) {
  		uart->old_line_ctrl_reg = inb(uart->base + UART_LCR);
  		outb(UART_LCR_DLAB	/* Divisor latch access bit */
  		     ,uart->base + UART_LCR);	/* Line Control Register */
  		uart->old_divisor_lsb = inb(uart->base + UART_DLL);
  		uart->old_divisor_msb = inb(uart->base + UART_DLM);
  
  		outb(uart->divisor
  		     ,uart->base + UART_DLL);	/* Divisor Latch Low */
  		outb(0
  		     ,uart->base + UART_DLM);	/* Divisor Latch High */
  		/* DLAB is reset to 0 in next outb() */
  	}
  	/* Set serial parameters (parity off, etc) */
  	outb(UART_LCR_WLEN8	/* 8 data-bits */
  	     | 0		/* 1 stop-bit */
  	     | 0		/* parity off */
  	     | 0		/* DLAB = 0 */
  	     ,uart->base + UART_LCR);	/* Line Control Register */
  
  	switch (uart->adaptor) {
  	default:
  		outb(UART_MCR_RTS	/* Set Request-To-Send line active */
  		     | UART_MCR_DTR	/* Set Data-Terminal-Ready line active */
  		     | UART_MCR_OUT2	/* Set OUT2 - not always required, but when
  					 * it is, it is ESSENTIAL for enabling interrupts
  				 */
  		     ,uart->base + UART_MCR);	/* Modem Control Register */
  		break;
  	case SNDRV_SERIAL_MS124W_SA:
  	case SNDRV_SERIAL_MS124W_MB:
  		/* MS-124W can draw power from RTS and DTR if they
  		   are in opposite states. */ 
  		outb(UART_MCR_RTS | (0&UART_MCR_DTR) | UART_MCR_OUT2,
  		     uart->base + UART_MCR);
  		break;
  	case SNDRV_SERIAL_MS124T:
  		/* MS-124T can draw power from RTS and/or DTR (preferably
  		   both) if they are both asserted. */
  		outb(UART_MCR_RTS | UART_MCR_DTR | UART_MCR_OUT2,
  		     uart->base + UART_MCR);
  		break;
  	}
  
  	if (uart->irq < 0) {
  		byte = (0 & UART_IER_RDI)	/* Disable Receiver data interrupt */
  		    |(0 & UART_IER_THRI)	/* Disable Transmitter holding register empty interrupt */
  		    ;
  	} else if (uart->adaptor == SNDRV_SERIAL_MS124W_SA) {
  		byte = UART_IER_RDI	/* Enable Receiver data interrupt */
  		    | UART_IER_MSI	/* Enable Modem status interrupt */
  		    ;
  	} else if (uart->adaptor == SNDRV_SERIAL_GENERIC) {
  		byte = UART_IER_RDI	/* Enable Receiver data interrupt */
  		    | UART_IER_MSI	/* Enable Modem status interrupt */
  		    | UART_IER_THRI	/* Enable Transmitter holding register empty interrupt */
  		    ;
  	} else {
  		byte = UART_IER_RDI	/* Enable Receiver data interrupt */
  		    | UART_IER_THRI	/* Enable Transmitter holding register empty interrupt */
  		    ;
  	}

  	outb(byte, uart->base + UART_IER);	/* Interrupt enable Register */

  
  	inb(uart->base + UART_LSR);	/* Clear any pre-existing overrun indication */
  	inb(uart->base + UART_IIR);	/* Clear any pre-existing transmit interrupt */
  	inb(uart->base + UART_RX);	/* Clear any pre-existing receive interrupt */
  }

  static void snd_uart16550_do_close(struct snd_uart16550 * uart)

  {
  	if (uart->irq < 0)
  		snd_uart16550_del_timer(uart);
  
  	/* NOTE: may need to disable interrupts before de-registering out handler.
  	 * For now, the consequences are harmless.
  	 */
  
  	outb((0 & UART_IER_RDI)		/* Disable Receiver data interrupt */
  	     |(0 & UART_IER_THRI)	/* Disable Transmitter holding register empty interrupt */

  	     ,uart->base + UART_IER);	/* Interrupt enable Register */

  
  	switch (uart->adaptor) {
  	default:
  		outb((0 & UART_MCR_RTS)		/* Deactivate Request-To-Send line  */
  		     |(0 & UART_MCR_DTR)	/* Deactivate Data-Terminal-Ready line */
  		     |(0 & UART_MCR_OUT2)	/* Deactivate OUT2 */
  		     ,uart->base + UART_MCR);	/* Modem Control Register */
  	  break;
  	case SNDRV_SERIAL_MS124W_SA:
  	case SNDRV_SERIAL_MS124W_MB:
  		/* MS-124W can draw power from RTS and DTR if they
  		   are in opposite states; leave it powered. */ 
  		outb(UART_MCR_RTS | (0&UART_MCR_DTR) | (0&UART_MCR_OUT2),
  		     uart->base + UART_MCR);
  		break;
  	case SNDRV_SERIAL_MS124T:
  		/* MS-124T can draw power from RTS and/or DTR (preferably
  		   both) if they are both asserted; leave it powered. */
  		outb(UART_MCR_RTS | UART_MCR_DTR | (0&UART_MCR_OUT2),
  		     uart->base + UART_MCR);
  		break;
  	}
  
  	inb(uart->base + UART_IIR);	/* Clear any outstanding interrupts */
  
  	/* Restore old divisor */
  	if (uart->divisor != 0) {
  		outb(UART_LCR_DLAB		/* Divisor latch access bit */
  		     ,uart->base + UART_LCR);	/* Line Control Register */
  		outb(uart->old_divisor_lsb
  		     ,uart->base + UART_DLL);	/* Divisor Latch Low */
  		outb(uart->old_divisor_msb
  		     ,uart->base + UART_DLM);	/* Divisor Latch High */
  		/* Restore old LCR (data bits, stop bits, parity, DLAB) */
  		outb(uart->old_line_ctrl_reg
  		     ,uart->base + UART_LCR);	/* Line Control Register */
  	}
  }

  static int snd_uart16550_input_open(struct snd_rawmidi_substream *substream)

  {
  	unsigned long flags;

  	struct snd_uart16550 *uart = substream->rmidi->private_data;

  
  	spin_lock_irqsave(&uart->open_lock, flags);
  	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
  		snd_uart16550_do_open(uart);
  	uart->filemode |= SERIAL_MODE_INPUT_OPEN;
  	uart->midi_input[substream->number] = substream;
  	spin_unlock_irqrestore(&uart->open_lock, flags);
  	return 0;
  }

  static int snd_uart16550_input_close(struct snd_rawmidi_substream *substream)

  {
  	unsigned long flags;

  	struct snd_uart16550 *uart = substream->rmidi->private_data;

  
  	spin_lock_irqsave(&uart->open_lock, flags);
  	uart->filemode &= ~SERIAL_MODE_INPUT_OPEN;
  	uart->midi_input[substream->number] = NULL;
  	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
  		snd_uart16550_do_close(uart);
  	spin_unlock_irqrestore(&uart->open_lock, flags);
  	return 0;
  }

  static void snd_uart16550_input_trigger(struct snd_rawmidi_substream *substream,
  					int up)

  {
  	unsigned long flags;

  	struct snd_uart16550 *uart = substream->rmidi->private_data;

  
  	spin_lock_irqsave(&uart->open_lock, flags);

  	if (up)

  		uart->filemode |= SERIAL_MODE_INPUT_TRIGGERED;

  	else

  		uart->filemode &= ~SERIAL_MODE_INPUT_TRIGGERED;

  	spin_unlock_irqrestore(&uart->open_lock, flags);
  }

  static int snd_uart16550_output_open(struct snd_rawmidi_substream *substream)

  {
  	unsigned long flags;

  	struct snd_uart16550 *uart = substream->rmidi->private_data;

  
  	spin_lock_irqsave(&uart->open_lock, flags);
  	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
  		snd_uart16550_do_open(uart);
  	uart->filemode |= SERIAL_MODE_OUTPUT_OPEN;
  	uart->midi_output[substream->number] = substream;
  	spin_unlock_irqrestore(&uart->open_lock, flags);
  	return 0;
  };

  static int snd_uart16550_output_close(struct snd_rawmidi_substream *substream)

  {
  	unsigned long flags;

  	struct snd_uart16550 *uart = substream->rmidi->private_data;

  
  	spin_lock_irqsave(&uart->open_lock, flags);
  	uart->filemode &= ~SERIAL_MODE_OUTPUT_OPEN;
  	uart->midi_output[substream->number] = NULL;
  	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
  		snd_uart16550_do_close(uart);
  	spin_unlock_irqrestore(&uart->open_lock, flags);
  	return 0;
  };

  static inline int snd_uart16550_buffer_can_write(struct snd_uart16550 *uart,
  						 int Num)

  {

  	if (uart->buff_in_count + Num < TX_BUFF_SIZE)

  		return 1;
  	else
  		return 0;
  }

  static inline int snd_uart16550_write_buffer(struct snd_uart16550 *uart,
  					     unsigned char byte)

  {
  	unsigned short buff_in = uart->buff_in;

  	if (uart->buff_in_count < TX_BUFF_SIZE) {

  		uart->tx_buff[buff_in] = byte;
  		buff_in++;
  		buff_in &= TX_BUFF_MASK;
  		uart->buff_in = buff_in;
  		uart->buff_in_count++;
  		if (uart->irq < 0) /* polling mode */
  			snd_uart16550_add_timer(uart);
  		return 1;
  	} else
  		return 0;
  }

  static int snd_uart16550_output_byte(struct snd_uart16550 *uart,
  				     struct snd_rawmidi_substream *substream,
  				     unsigned char midi_byte)

  {

  	if (uart->buff_in_count == 0                    /* Buffer empty? */

  	    && ((uart->adaptor != SNDRV_SERIAL_MS124W_SA &&
  	    uart->adaptor != SNDRV_SERIAL_GENERIC) ||

  		(uart->fifo_count == 0                  /* FIFO empty? */

  		 && (inb(uart->base + UART_MSR) & UART_MSR_CTS)))) { /* CTS? */
  
  	        /* Tx Buffer Empty - try to write immediately */
  		if ((inb(uart->base + UART_LSR) & UART_LSR_THRE) != 0) {
  		        /* Transmitter holding register (and Tx FIFO) empty */
  		        uart->fifo_count = 1;
  			outb(midi_byte, uart->base + UART_TX);
  		} else {
  		        if (uart->fifo_count < uart->fifo_limit) {
  			        uart->fifo_count++;
  				outb(midi_byte, uart->base + UART_TX);
  			} else {

  			        /* Cannot write (buffer empty) -
  				 * put char in buffer */

  				snd_uart16550_write_buffer(uart, midi_byte);
  			}
  		}
  	} else {

  		if (!snd_uart16550_write_buffer(uart, midi_byte)) {

  			snd_printk(KERN_WARNING
  				   "%s: Buffer overrun on device at 0x%lx
  ",

  				   uart->rmidi->name, uart->base);
  			return 0;
  		}
  	}
  
  	return 1;
  }

  static void snd_uart16550_output_write(struct snd_rawmidi_substream *substream)

  {
  	unsigned long flags;
  	unsigned char midi_byte, addr_byte;

  	struct snd_uart16550 *uart = substream->rmidi->private_data;

  	char first;

  	static unsigned long lasttime = 0;

  	/* Interrupts are disabled during the updating of the tx_buff,

  	 * since it is 'bad' to have two processes updating the same
  	 * variables (ie buff_in & buff_out)
  	 */
  
  	spin_lock_irqsave(&uart->open_lock, flags);

  	if (uart->irq < 0)	/* polling */

  		snd_uart16550_io_loop(uart);
  
  	if (uart->adaptor == SNDRV_SERIAL_MS124W_MB) {
  		while (1) {
  			/* buffer full? */
  			/* in this mode we need two bytes of space */
  			if (uart->buff_in_count > TX_BUFF_SIZE - 2)
  				break;
  			if (snd_rawmidi_transmit(substream, &midi_byte, 1) != 1)
  				break;
  #ifdef SNDRV_SERIAL_MS124W_MB_NOCOMBO
  			/* select exactly one of the four ports */
  			addr_byte = (1 << (substream->number + 4)) | 0x08;
  #else
  			/* select any combination of the four ports */
  			addr_byte = (substream->number << 4) | 0x08;
  			/* ...except none */

  			if (addr_byte == 0x08)
  				addr_byte = 0xf8;

  #endif
  			snd_uart16550_output_byte(uart, substream, addr_byte);
  			/* send midi byte */
  			snd_uart16550_output_byte(uart, substream, midi_byte);
  		}
  	} else {
  		first = 0;

  		while (snd_rawmidi_transmit_peek(substream, &midi_byte, 1) == 1) {
  			/* Also send F5 after 3 seconds with no data
  			 * to handle device disconnect */
  			if (first == 0 &&
  			    (uart->adaptor == SNDRV_SERIAL_SOUNDCANVAS ||
  			     uart->adaptor == SNDRV_SERIAL_GENERIC) &&
  			    (uart->prev_out != substream->number ||

  			     time_after(jiffies, lasttime + 3*HZ))) {

  
  				if (snd_uart16550_buffer_can_write(uart, 3)) {

  					/* Roland Soundcanvas part selection */

  					/* If this substream of the data is
  					 * different previous substream
  					 * in this uart, send the change part
  					 * event
  					 */

  					uart->prev_out = substream->number;
  					/* change part */

  					snd_uart16550_output_byte(uart, substream,
  								  0xf5);

  					/* data */

  					snd_uart16550_output_byte(uart, substream,
  								  uart->prev_out + 1);
  					/* If midi_byte is a data byte,
  					 * send the previous status byte */
  					if (midi_byte < 0x80 &&
  					    uart->adaptor == SNDRV_SERIAL_SOUNDCANVAS)

  						snd_uart16550_output_byte(uart, substream, uart->prev_status[uart->prev_out]);

  				} else if (!uart->drop_on_full)

  					break;
  
  			}
  
  			/* send midi byte */

  			if (!snd_uart16550_output_byte(uart, substream, midi_byte) &&
  			    !uart->drop_on_full )

  				break;
  
  			if (midi_byte >= 0x80 && midi_byte < 0xf0)
  				uart->prev_status[uart->prev_out] = midi_byte;
  			first = 1;
  
  			snd_rawmidi_transmit_ack( substream, 1 );
  		}
  		lasttime = jiffies;
  	}
  	spin_unlock_irqrestore(&uart->open_lock, flags);
  }

  static void snd_uart16550_output_trigger(struct snd_rawmidi_substream *substream,
  					 int up)

  {
  	unsigned long flags;

  	struct snd_uart16550 *uart = substream->rmidi->private_data;

  
  	spin_lock_irqsave(&uart->open_lock, flags);

  	if (up)

  		uart->filemode |= SERIAL_MODE_OUTPUT_TRIGGERED;

  	else

  		uart->filemode &= ~SERIAL_MODE_OUTPUT_TRIGGERED;

  	spin_unlock_irqrestore(&uart->open_lock, flags);
  	if (up)
  		snd_uart16550_output_write(substream);
  }

  static struct snd_rawmidi_ops snd_uart16550_output =

  {
  	.open =		snd_uart16550_output_open,
  	.close =	snd_uart16550_output_close,
  	.trigger =	snd_uart16550_output_trigger,
  };

  static struct snd_rawmidi_ops snd_uart16550_input =

  {
  	.open =		snd_uart16550_input_open,
  	.close =	snd_uart16550_input_close,
  	.trigger =	snd_uart16550_input_trigger,
  };

  static int snd_uart16550_free(struct snd_uart16550 *uart)

  {
  	if (uart->irq >= 0)

  		free_irq(uart->irq, uart);

  	release_and_free_resource(uart->res_base);

  	kfree(uart);
  	return 0;
  };

  static int snd_uart16550_dev_free(struct snd_device *device)

  {

  	struct snd_uart16550 *uart = device->device_data;

  	return snd_uart16550_free(uart);
  }

  static int __devinit snd_uart16550_create(struct snd_card *card,

  				       unsigned long iobase,
  				       int irq,
  				       unsigned int speed,
  				       unsigned int base,
  				       int adaptor,
  				       int droponfull,

  				       struct snd_uart16550 **ruart)

  {

  	static struct snd_device_ops ops = {

  		.dev_free =	snd_uart16550_dev_free,
  	};

  	struct snd_uart16550 *uart;

  	int err;

  	if ((uart = kzalloc(sizeof(*uart), GFP_KERNEL)) == NULL)

  		return -ENOMEM;
  	uart->adaptor = adaptor;
  	uart->card = card;
  	spin_lock_init(&uart->open_lock);
  	uart->irq = -1;
  	uart->base = iobase;
  	uart->drop_on_full = droponfull;
  
  	if ((err = snd_uart16550_detect(uart)) <= 0) {
  		printk(KERN_ERR "no UART detected at 0x%lx
  ", iobase);

  		snd_uart16550_free(uart);

  		return -ENODEV;

  	}
  
  	if (irq >= 0 && irq != SNDRV_AUTO_IRQ) {
  		if (request_irq(irq, snd_uart16550_interrupt,

  				0, "Serial MIDI", uart)) {

  			snd_printk(KERN_WARNING
  				   "irq %d busy. Using Polling.
  ", irq);

  		} else {
  			uart->irq = irq;
  		}
  	}
  	uart->divisor = base / speed;
  	uart->speed = base / (unsigned int)uart->divisor;
  	uart->speed_base = base;
  	uart->prev_out = -1;
  	uart->prev_in = 0;
  	uart->rstatus = 0;
  	memset(uart->prev_status, 0x80, sizeof(unsigned char) * SNDRV_SERIAL_MAX_OUTS);
  	init_timer(&uart->buffer_timer);
  	uart->buffer_timer.function = snd_uart16550_buffer_timer;
  	uart->buffer_timer.data = (unsigned long)uart;
  	uart->timer_running = 0;
  
  	/* Register device */
  	if ((err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, uart, &ops)) < 0) {
  		snd_uart16550_free(uart);
  		return err;
  	}
  
  	switch (uart->adaptor) {
  	case SNDRV_SERIAL_MS124W_SA:
  	case SNDRV_SERIAL_MS124W_MB:
  		/* MS-124W can draw power from RTS and DTR if they
  		   are in opposite states. */ 
  		outb(UART_MCR_RTS | (0&UART_MCR_DTR), uart->base + UART_MCR);
  		break;
  	case SNDRV_SERIAL_MS124T:
  		/* MS-124T can draw power from RTS and/or DTR (preferably
  		   both) if they are asserted. */
  		outb(UART_MCR_RTS | UART_MCR_DTR, uart->base + UART_MCR);
  		break;
  	default:
  		break;
  	}
  
  	if (ruart)
  		*ruart = uart;
  
  	return 0;
  }

  static void __devinit snd_uart16550_substreams(struct snd_rawmidi_str *stream)

  {

  	struct snd_rawmidi_substream *substream;

  	list_for_each_entry(substream, &stream->substreams, list) {

  		sprintf(substream->name, "Serial MIDI %d", substream->number + 1);
  	}
  }

  static int __devinit snd_uart16550_rmidi(struct snd_uart16550 *uart, int device,

  				      int outs, int ins,
  				      struct snd_rawmidi **rmidi)

  {

  	struct snd_rawmidi *rrawmidi;

  	int err;

  	err = snd_rawmidi_new(uart->card, "UART Serial MIDI", device,
  			      outs, ins, &rrawmidi);
  	if (err < 0)

  		return err;

  	snd_rawmidi_set_ops(rrawmidi, SNDRV_RAWMIDI_STREAM_INPUT,
  			    &snd_uart16550_input);
  	snd_rawmidi_set_ops(rrawmidi, SNDRV_RAWMIDI_STREAM_OUTPUT,
  			    &snd_uart16550_output);

  	strcpy(rrawmidi->name, "Serial MIDI");
  	snd_uart16550_substreams(&rrawmidi->streams[SNDRV_RAWMIDI_STREAM_OUTPUT]);
  	snd_uart16550_substreams(&rrawmidi->streams[SNDRV_RAWMIDI_STREAM_INPUT]);
  	rrawmidi->info_flags = SNDRV_RAWMIDI_INFO_OUTPUT |
  			       SNDRV_RAWMIDI_INFO_INPUT |
  			       SNDRV_RAWMIDI_INFO_DUPLEX;
  	rrawmidi->private_data = uart;
  	if (rmidi)
  		*rmidi = rrawmidi;
  	return 0;
  }

  static int __devinit snd_serial_probe(struct platform_device *devptr)

  {

  	struct snd_card *card;

  	struct snd_uart16550 *uart;

  	int err;

  	int dev = devptr->id;

  
  	switch (adaptor[dev]) {
  	case SNDRV_SERIAL_SOUNDCANVAS:
  		ins[dev] = 1;
  		break;
  	case SNDRV_SERIAL_MS124T:
  	case SNDRV_SERIAL_MS124W_SA:
  		outs[dev] = 1;
  		ins[dev] = 1;
  		break;
  	case SNDRV_SERIAL_MS124W_MB:
  		outs[dev] = 16;
  		ins[dev] = 1;
  		break;
  	case SNDRV_SERIAL_GENERIC:
  		break;
  	default:

  		snd_printk(KERN_ERR
  			   "Adaptor type is out of range 0-%d (%d)
  ",

  			   SNDRV_SERIAL_MAX_ADAPTOR, adaptor[dev]);
  		return -ENODEV;
  	}
  
  	if (outs[dev] < 1 || outs[dev] > SNDRV_SERIAL_MAX_OUTS) {

  		snd_printk(KERN_ERR
  			   "Count of outputs is out of range 1-%d (%d)
  ",

  			   SNDRV_SERIAL_MAX_OUTS, outs[dev]);
  		return -ENODEV;
  	}
  
  	if (ins[dev] < 1 || ins[dev] > SNDRV_SERIAL_MAX_INS) {

  		snd_printk(KERN_ERR
  			   "Count of inputs is out of range 1-%d (%d)
  ",

  			   SNDRV_SERIAL_MAX_INS, ins[dev]);
  		return -ENODEV;
  	}

  	err  = snd_card_create(index[dev], id[dev], THIS_MODULE, 0, &card);
  	if (err < 0)
  		return err;

  
  	strcpy(card->driver, "Serial");
  	strcpy(card->shortname, "Serial MIDI (UART16550A)");
  
  	if ((err = snd_uart16550_create(card,
  					port[dev],
  					irq[dev],
  					speed[dev],
  					base[dev],
  					adaptor[dev],
  					droponfull[dev],

  					&uart)) < 0)
  		goto _err;

  	err = snd_uart16550_rmidi(uart, 0, outs[dev], ins[dev], &uart->rmidi);
  	if (err < 0)

  		goto _err;

  	sprintf(card->longname, "%s [%s] at %#lx, irq %d",

  		card->shortname,

  		adaptor_names[uart->adaptor],

  		uart->base,
  		uart->irq);

  	snd_card_set_dev(card, &devptr->dev);

  
  	if ((err = snd_card_register(card)) < 0)
  		goto _err;

  	platform_set_drvdata(devptr, card);

  	return 0;

  
   _err:
  	snd_card_free(card);
  	return err;

  }

  static int __devexit snd_serial_remove(struct platform_device *devptr)

  {
  	snd_card_free(platform_get_drvdata(devptr));
  	platform_set_drvdata(devptr, NULL);
  	return 0;
  }
  
  #define SND_SERIAL_DRIVER	"snd_serial_u16550"
  
  static struct platform_driver snd_serial_driver = {
  	.probe		= snd_serial_probe,

  	.remove		= __devexit_p( snd_serial_remove),

  	.driver		= {
  		.name	= SND_SERIAL_DRIVER
  	},
  };

  static void snd_serial_unregister_all(void)

  {
  	int i;
  
  	for (i = 0; i < ARRAY_SIZE(devices); ++i)
  		platform_device_unregister(devices[i]);
  	platform_driver_unregister(&snd_serial_driver);
  }

  static int __init alsa_card_serial_init(void)
  {

  	int i, cards, err;

  	if ((err = platform_driver_register(&snd_serial_driver)) < 0)
  		return err;

  	cards = 0;

  	for (i = 0; i < SNDRV_CARDS; i++) {

  		struct platform_device *device;

  		if (! enable[i])
  			continue;

  		device = platform_device_register_simple(SND_SERIAL_DRIVER,
  							 i, NULL, 0);

  		if (IS_ERR(device))
  			continue;

  		if (!platform_get_drvdata(device)) {
  			platform_device_unregister(device);
  			continue;
  		}

  		devices[i] = device;

  		cards++;
  	}
  	if (! cards) {

  #ifdef MODULE
  		printk(KERN_ERR "serial midi soundcard not found or device busy
  ");
  #endif

  		snd_serial_unregister_all();
  		return -ENODEV;

  	}
  	return 0;
  }
  
  static void __exit alsa_card_serial_exit(void)
  {

  	snd_serial_unregister_all();

  }
  
  module_init(alsa_card_serial_init)
  module_exit(alsa_card_serial_exit)