ftdi_sio.c

讲述linux的初始化过程

/*
 * USB FTDI SIO driver
 *
 * 	Copyright (C) 1999, 2000
 * 	    Greg Kroah-Hartman ([e-mail])
 *          Bill Ryder ([e-mail])
 *
 * 	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.
 *
 * See Documentation/usb/usb-serial.txt for more information on using this driver
 *
 * See http://reality.sgi.com/bryder_wellington/ftdi_sio for upto date testing info
 *     and extra documentation
 *       
 * (12/3/2000) Bill Ryder
 *     Added support for 8U232AM device.
 *     Moved PID and VIDs into header file only.
 *     Turned on low-latency for the tty (device will do high baudrates)
 *     Added shutdown routine to close files when device removed.
 *     More debug and error message cleanups.
 *     
 *
 * (11/13/2000) Bill Ryder
 *     Added spinlock protected open code and close code.
 *     Multiple opens work (sort of - see webpage mentioned above).
 *     Cleaned up comments. Removed multiple PID/VID definitions.
 *     Factorised cts/dtr code
 *     Made use of __FUNCTION__ in dbg's
 *      
 * (11/01/2000) Adam J. Richter
 *	usb_device_id table support
 * 
 * (10/05/2000) gkh
 *	Fixed bug with urb->dev not being set properly, now that the usb
 *	core needs it.
 * 
 * (09/11/2000) gkh
 *	Removed DEBUG #ifdefs with call to usb_serial_debug_data
 *
 * (07/19/2000) gkh
 *	Added module_init and module_exit functions to handle the fact that this
 *	driver is a loadable module now.
 *
 * (04/04/2000) Bill Ryder 
 *      Fixed bugs in TCGET/TCSET ioctls (by removing them - they are 
 *        handled elsewhere in the tty io driver chain).
 *
 * (03/30/2000) Bill Ryder 
 *      Implemented lots of ioctls
 * 	Fixed a race condition in write
 * 	Changed some dbg's to errs
 *
 * (03/26/2000) gkh
 * 	Split driver up into device specific pieces.
 *
 */

/* Bill Ryder - [e-mail] - wrote the FTDI_SIO implementation */
/* Thanx to FTDI for so kindly providing details of the protocol required */
/*   to talk to the device */
/* Thanx to gkh and the rest of the usb dev group for all code I have assimilated :-) */


#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/malloc.h>
#include <linux/fcntl.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/tty.h>
#include <linux/module.h>
#include <linux/spinlock.h>

#ifdef CONFIG_USB_SERIAL_DEBUG
	#define DEBUG
#else
	#undef DEBUG
#endif
#include <linux/usb.h>

#include "usb-serial.h"

#include "ftdi_sio.h"


static __devinitdata struct usb_device_id id_table_sio [] = {
	{ USB_DEVICE(FTDI_VID, FTDI_SIO_PID) },
	{ }						/* Terminating entry */
};

/* THe 8U232AM has the same API as the sio - but it can support MUCH 
   higher baudrates (921600 at 48MHz/230400 at 12MHz 
   so .. it's baudrate setting codes are different */

   
static __devinitdata struct usb_device_id id_table_8U232AM [] = {
	{ USB_DEVICE(FTDI_VID, FTDI_8U232AM_PID) },
	{ }						/* Terminating entry */
};


static __devinitdata struct usb_device_id id_table_combined [] = {
	{ USB_DEVICE(FTDI_VID, FTDI_SIO_PID) },
	{ USB_DEVICE(FTDI_VID, FTDI_8U232AM_PID) },
	{ }						/* Terminating entry */
};

MODULE_DEVICE_TABLE (usb, id_table_combined);


struct ftdi_private {
	ftdi_type_t ftdi_type;
	char last_status_byte; /* device sends this every 40ms when open */
	
	
};
/* function prototypes for a FTDI serial converter */
static int  ftdi_sio_startup		(struct usb_serial *serial);
static int  ftdi_8U232AM_startup	(struct usb_serial *serial);
static void ftdi_sio_shutdown		(struct usb_serial *serial);
static int  ftdi_sio_open		(struct usb_serial_port *port, struct file *filp);
static void ftdi_sio_close		(struct usb_serial_port *port, struct file *filp);
static int  ftdi_sio_write		(struct usb_serial_port *port, int from_user, const unsigned char *buf, int count);
static void ftdi_sio_write_bulk_callback (struct urb *urb);
static void ftdi_sio_read_bulk_callback	(struct urb *urb);
static void ftdi_sio_set_termios	(struct usb_serial_port *port, struct termios * old);
static int  ftdi_sio_ioctl		(struct usb_serial_port *port, struct file * file, unsigned int cmd, unsigned long arg);

/* Should rename most ftdi_sio's to ftdi_ now since there are two devices 
   which share common code */ 

struct usb_serial_device_type ftdi_sio_device = {
	name:			"FTDI SIO",
	id_table:		id_table_sio,
	needs_interrupt_in:	MUST_HAVE_NOT,
	needs_bulk_in:		MUST_HAVE,
	needs_bulk_out:		MUST_HAVE,
	num_interrupt_in:	0,
	num_bulk_in:		1,
	num_bulk_out:		1,
	num_ports:		1,
	open:			ftdi_sio_open,
	close:			ftdi_sio_close,
	write:			ftdi_sio_write,
	read_bulk_callback:	ftdi_sio_read_bulk_callback,
	write_bulk_callback:	ftdi_sio_write_bulk_callback,
	ioctl:			ftdi_sio_ioctl,
	set_termios:		ftdi_sio_set_termios,
	startup:		ftdi_sio_startup,
        shutdown:               ftdi_sio_shutdown,
};

struct usb_serial_device_type ftdi_8U232AM_device = {
	name:			"FTDI 8U232AM",
	id_table:		id_table_8U232AM,
	needs_interrupt_in:	DONT_CARE,
	needs_bulk_in:		MUST_HAVE,
	needs_bulk_out:		MUST_HAVE,
	num_interrupt_in:	0,
	num_bulk_in:		1,
	num_bulk_out:		1,
	num_ports:		1,
	open:			ftdi_sio_open,
	close:			ftdi_sio_close,
	write:			ftdi_sio_write,
	read_bulk_callback:	ftdi_sio_read_bulk_callback,
	write_bulk_callback:	ftdi_sio_write_bulk_callback,
	ioctl:			ftdi_sio_ioctl,
	set_termios:		ftdi_sio_set_termios,
	startup:		ftdi_8U232AM_startup,
        shutdown:               ftdi_sio_shutdown,
};


/*
 * ***************************************************************************
 * FTDI SIO Serial Converter specific driver functions
 * ***************************************************************************
 */

#define WDR_TIMEOUT (HZ * 5 ) /* default urb timeout */

/* utility functions to set and unset dtr and rts */
#define HIGH 1
#define LOW 0
static int set_rts(struct usb_device *dev, 
		   unsigned int pipe,
		   int high_or_low)
{
	static char buf[1];
	unsigned ftdi_high_or_low = (high_or_low? FTDI_SIO_SET_RTS_HIGH : 
				FTDI_SIO_SET_RTS_LOW);
	return(usb_control_msg(dev, pipe,
			       FTDI_SIO_SET_MODEM_CTRL_REQUEST, 
			       FTDI_SIO_SET_MODEM_CTRL_REQUEST_TYPE,
			       ftdi_high_or_low, 0, 
			       buf, 0, WDR_TIMEOUT));
}
static int set_dtr(struct usb_device *dev, 
		   unsigned int pipe,
		   int high_or_low)
{
	static char buf[1];
	unsigned ftdi_high_or_low = (high_or_low? FTDI_SIO_SET_DTR_HIGH : 
				FTDI_SIO_SET_DTR_LOW);
	return(usb_control_msg(dev, pipe,
			       FTDI_SIO_SET_MODEM_CTRL_REQUEST, 
			       FTDI_SIO_SET_MODEM_CTRL_REQUEST_TYPE,
			       ftdi_high_or_low, 0, 
			       buf, 0, WDR_TIMEOUT));
}



static int ftdi_sio_startup (struct usb_serial *serial)
{
	struct ftdi_private *priv;
	
	init_waitqueue_head(&serial->port[0].write_wait);
	
	priv = serial->port->private = kmalloc(sizeof(struct ftdi_private), GFP_KERNEL);
	if (!priv){
		err(__FUNCTION__"- kmalloc(%d) failed.", sizeof(struct ftdi_private));
		return -ENOMEM;
	}

	priv->ftdi_type = sio;
	
	return (0);
}


static int ftdi_8U232AM_startup (struct usb_serial *serial)
{
	struct ftdi_private *priv;
 
	init_waitqueue_head(&serial->port[0].write_wait);

	priv = serial->port->private = kmalloc(sizeof(struct ftdi_private), GFP_KERNEL);
	if (!priv){
		err(__FUNCTION__"- kmalloc(%d) failed.", sizeof(struct ftdi_private));
		return -ENOMEM;
	}

	priv->ftdi_type = F8U232AM;
	
	return (0);
}

static void ftdi_sio_shutdown (struct usb_serial *serial)
{
	
	dbg (__FUNCTION__);

	/* Close ports if they are open */
	while (serial->port[0].open_count > 0) {
		ftdi_sio_close (&serial->port[0], NULL);
	}
	if (serial->port->private){
		kfree(serial->port->private);
		serial->port->private = NULL;
	}
}



static int  ftdi_sio_open (struct usb_serial_port *port, struct file *filp)
{ /* ftdi_sio_open */
	struct termios tmp_termios;
	struct usb_serial *serial = port->serial;
	unsigned long flags;	/* Used for spinlock */
	int result;
	char buf[1]; /* Needed for the usb_control_msg I think */

	dbg(__FUNCTION__);

	spin_lock_irqsave (&port->port_lock, flags);
	
	MOD_INC_USE_COUNT;
	++port->open_count;

	if (!port->active){
		port->active = 1;

		spin_unlock_irqrestore (&port->port_lock, flags);

		/* do not allow a task to be queued to deliver received data */
		port->tty->low_latency = 1;

		/* No error checking for this (will get errors later anyway) */
		/* See ftdi_sio.h for description of what is reset */
		usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
				FTDI_SIO_RESET_REQUEST, FTDI_SIO_RESET_REQUEST_TYPE, 
				FTDI_SIO_RESET_SIO, 
				0, buf, 0, WDR_TIMEOUT);

		/* Setup termios defaults. According to tty_io.c the 
		   settings are driver specific */
		port->tty->termios->c_cflag =
			B9600 | CS8 | CREAD | HUPCL | CLOCAL;

		/* ftdi_sio_set_termios  will send usb control messages */
		ftdi_sio_set_termios(port, &tmp_termios);	

		/* Turn on RTS and DTR since we are not flow controlling by default */
		if (set_dtr(serial->dev, usb_sndctrlpipe(serial->dev, 0),HIGH) < 0) {
			err(__FUNCTION__ " Error from DTR HIGH urb");
		}
		if (set_rts(serial->dev, usb_sndctrlpipe(serial->dev, 0),HIGH) < 0){
			err(__FUNCTION__ " Error from RTS HIGH urb");
		}
	
		/* Start reading from the device */
		FILL_BULK_URB(port->read_urb, serial->dev, 
			      usb_rcvbulkpipe(serial->dev, port->bulk_in_endpointAddress),
			      port->read_urb->transfer_buffer, port->read_urb->transfer_buffer_length,
			      ftdi_sio_read_bulk_callback, port);
		result = usb_submit_urb(port->read_urb);
		if (result)
			err(__FUNCTION__ " - failed submitting read urb, error %d", result);
	} else { /* the port was already active - so no initialisation is done */
		spin_unlock_irqrestore (&port->port_lock, flags);
	}

	return (0);
} /* ftdi_sio_open */


static void ftdi_sio_close (struct usb_serial_port *port, struct file *filp)
{ /* ftdi_sio_close */
	struct usb_serial *serial = port->serial;
	unsigned int c_cflag = port->tty->termios->c_cflag;
	char buf[1];
	unsigned long flags;

	dbg( __FUNCTION__);

	spin_lock_irqsave (&port->port_lock, flags);
	--port->open_count;

	if (port->open_count <= 0) {
		spin_unlock_irqrestore (&port->port_lock, flags);
		if (c_cflag & HUPCL){
			/* Disable flow control */
			if (usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
					    FTDI_SIO_SET_FLOW_CTRL_REQUEST, 
					    FTDI_SIO_SET_FLOW_CTRL_REQUEST_TYPE,
					    0, 0, 
					    buf, 0, WDR_TIMEOUT) < 0) {
				err("error from flowcontrol urb");
			}	    

			/* drop DTR */
			if (set_dtr(serial->dev, usb_sndctrlpipe(serial->dev, 0), LOW) < 0){
				err("Error from DTR LOW urb");
			}
			/* drop RTS */
			if (set_rts(serial->dev, usb_sndctrlpipe(serial->dev, 0),LOW) < 0) {
				err("Error from RTS LOW urb");
			}	
		} /* Note change no line is hupcl is off */

		/* shutdown our bulk reads and writes */
		usb_unlink_urb (port->write_urb);
		usb_unlink_urb (port->read_urb);
		port->active = 0;
		port->open_count = 0;
	} else {  
		spin_unlock_irqrestore (&port->port_lock, flags);

		/* Send a HUP if necessary */
		if (!(port->tty->termios->c_cflag & CLOCAL)){
			tty_hangup(port->tty);
		}
		
	}

	MOD_DEC_USE_COUNT;

} /* ftdi_sio_close */


  
/* The ftdi_sio requires the first byte to have:
 *  B0 1
 *  B1 0
 *  B2..7 length of message excluding byte 0
 */
static int ftdi_sio_write (struct usb_serial_port *port, int from_user, 
			   const unsigned char *buf, int count)
{ /* ftdi_sio_write */
	struct usb_serial *serial = port->serial;
	struct ftdi_private *priv = (struct ftdi_private *)port->private;
	int data_offset ;
	int rc; 
	int result;
	DECLARE_WAITQUEUE(wait, current);
	
	dbg(__FUNCTION__ " port %d, %d bytes", port->number, count);

	if (count == 0) {
		err("write request of 0 bytes");
		return 0;
	}
	
	if (priv->ftdi_type == sio){
		data_offset = 1;
	} else {
		data_offset = 0;
	}
        dbg("data_offset set to %d",data_offset);

	/* only do something if we have a bulk out endpoint */
	if (serial->num_bulk_out) {
		unsigned char *first_byte = port->write_urb->transfer_buffer;

		/* Was seeing a race here, got a read callback, then write callback before
		   hitting interuptible_sleep_on  - so wrapping in a wait_queue */

		add_wait_queue(&port->write_wait, &wait);
		set_current_state (TASK_INTERRUPTIBLE);
		while (port->write_urb->status == -EINPROGRESS) {
			dbg(__FUNCTION__ " write in progress - retrying");
			if (signal_pending(current)) {
				current->state = TASK_RUNNING;
				remove_wait_queue(&port->write_wait, &wait);
				rc = -ERESTARTSYS;
				goto err;
			}
			schedule();
		}		
		remove_wait_queue(&port->write_wait, &wait);
		set_current_state(TASK_RUNNING);