serial-u16550.c

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/*
 *   serial.c
 *   Copyright (c) by Jaroslav Kysela <[e-mail]>,
 *                    Isaku Yamahata <[e-mail]>,
 *		      George Hansper <[e-mail]>,
 *		      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 [e-mail] 
 *      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 <sound/driver.h>
#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/moduleparam.h>
#include <sound/core.h>
#include <sound/rawmidi.h>
#include <sound/initval.h>

#include <linux/serial_reg.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 int 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 int 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("%s: Overrun on device at 0x%lx\n",
			       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\n", 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 */