/*
 * cdc-acm.c
 *
 * Copyright (c) 1999 Armin Fuerst	<fuerst@in.tum.de>
 * Copyright (c) 1999 Pavel Machek	<pavel@suse.cz>
 * Copyright (c) 1999 Johannes Erdfelt	<johannes@erdfelt.com>
 * Copyright (c) 2000 Vojtech Pavlik	<vojtech@suse.cz>
 * Copyright (c) 2004 Oliver Neukum	<oliver@neukum.name>
 *
 * USB Abstract Control Model driver for USB modems and ISDN adapters
 *
 * Sponsored by SuSE
 *
 * ChangeLog:
 *	v0.9  - thorough cleaning, URBification, almost a rewrite
 *	v0.10 - some more cleanups
 *	v0.11 - fixed flow control, read error doesn't stop reads
 *	v0.12 - added TIOCM ioctls, added break handling, made struct acm kmalloced
 *	v0.13 - added termios, added hangup
 *	v0.14 - sized down struct acm
 *	v0.15 - fixed flow control again - characters could be lost
 *	v0.16 - added code for modems with swapped data and control interfaces
 *	v0.17 - added new style probing
 *	v0.18 - fixed new style probing for devices with more configurations
 *	v0.19 - fixed CLOCAL handling (thanks to Richard Shih-Ping Chan)
 *	v0.20 - switched to probing on interface (rather than device) class
 *	v0.21 - revert to probing on device for devices with multiple configs
 *	v0.22 - probe only the control interface. if usbcore doesn't choose the
 *		config we want, sysadmin changes bConfigurationValue in sysfs.
 *	v0.23 - use softirq for rx processing, as needed by tty layer
 *	v0.24 - change probe method to evaluate CDC union descriptor
 */

/*
 * 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
 */

#undef DEBUG

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/module.h>
#include <linux/smp_lock.h>
#include <asm/uaccess.h>
#include <linux/usb.h>
#include <asm/byteorder.h>
#include <asm/unaligned.h>

#include "cdc-acm.h"

/*
 * Version Information
 */
#define DRIVER_VERSION "v0.23"
#define DRIVER_AUTHOR "Armin Fuerst, Pavel Machek, Johannes Erdfelt, Vojtech Pavlik"
#define DRIVER_DESC "USB Abstract Control Model driver for USB modems and ISDN adapters"

static struct usb_driver acm_driver;
static struct tty_driver *acm_tty_driver;
static struct acm *acm_table[ACM_TTY_MINORS];

static DECLARE_MUTEX(open_sem);

#define ACM_READY(acm)	(acm && acm->dev && acm->used)

/*
 * Functions for ACM control messages.
 */

static int acm_ctrl_msg(struct acm *acm, int request, int value, void *buf, int len)
{
	int retval = usb_control_msg(acm->dev, usb_sndctrlpipe(acm->dev, 0),
		request, USB_RT_ACM, value,
		acm->control->altsetting[0].desc.bInterfaceNumber,
		buf, len, HZ * 5);
	dbg("acm_control_msg: rq: 0x%02x val: %#x len: %#x result: %d", request, value, len, retval);
	return retval < 0 ? retval : 0;
}

/* devices aren't required to support these requests.
 * the cdc acm descriptor tells whether they do...
 */
#define acm_set_control(acm, control)	acm_ctrl_msg(acm, ACM_REQ_SET_CONTROL, control, NULL, 0)
#define acm_set_line(acm, line)		acm_ctrl_msg(acm, ACM_REQ_SET_LINE, 0, line, sizeof(struct acm_line))
#define acm_send_break(acm, ms)		acm_ctrl_msg(acm, ACM_REQ_SEND_BREAK, ms, NULL, 0)

/*
 * Interrupt handlers for various ACM device responses
 */

/* control interface reports status changes with "interrupt" transfers */
static void acm_ctrl_irq(struct urb *urb, struct pt_regs *regs)
{
	struct acm *acm = urb->context;
	struct usb_ctrlrequest *dr = urb->transfer_buffer;
	unsigned char *data;
	int newctrl;
	int status;

	switch (urb->status) {
	case 0:
		/* success */
		break;
	case -ECONNRESET:
	case -ENOENT:
	case -ESHUTDOWN:
		/* this urb is terminated, clean up */
		dbg("%s - urb shutting down with status: %d", __FUNCTION__, urb->status);
		return;
	default:
		dbg("%s - nonzero urb status received: %d", __FUNCTION__, urb->status);
		goto exit;
	}

	if (!ACM_READY(acm))
		goto exit;

	data = (unsigned char *)(dr + 1);
	switch (dr->bRequest) {

		case ACM_IRQ_NETWORK:

			dbg("%s network", dr->wValue ? "connected to" : "disconnected from");
			break;

		case ACM_IRQ_LINE_STATE:

			newctrl = le16_to_cpu(get_unaligned((__le16 *) data));

			if (acm->tty && !acm->clocal && (acm->ctrlin & ~newctrl & ACM_CTRL_DCD)) {
				dbg("calling hangup");
				tty_hangup(acm->tty);
			}

			acm->ctrlin = newctrl;

			dbg("input control lines: dcd%c dsr%c break%c ring%c framing%c parity%c overrun%c",
				acm->ctrlin & ACM_CTRL_DCD ? '+' : '-',	acm->ctrlin & ACM_CTRL_DSR ? '+' : '-',
				acm->ctrlin & ACM_CTRL_BRK ? '+' : '-',	acm->ctrlin & ACM_CTRL_RI  ? '+' : '-',
				acm->ctrlin & ACM_CTRL_FRAMING ? '+' : '-',	acm->ctrlin & ACM_CTRL_PARITY ? '+' : '-',
				acm->ctrlin & ACM_CTRL_OVERRUN ? '+' : '-');

			break;

		default:
			dbg("unknown control event received: request %d index %d len %d data0 %d data1 %d",
				dr->bRequest, dr->wIndex, dr->wLength, data[0], data[1]);
			break;
	}
exit:
	status = usb_submit_urb (urb, GFP_ATOMIC);
	if (status)
		err ("%s - usb_submit_urb failed with result %d",
		     __FUNCTION__, status);
}

/* data interface returns incoming bytes, or we got unthrottled */
static void acm_read_bulk(struct urb *urb, struct pt_regs *regs)
{
	struct acm *acm = urb->context;
	dbg("Entering acm_read_bulk with status %d\n", urb->status);

	if (!ACM_READY(acm))
		return;

	if (urb->status)
		dev_dbg(&acm->data->dev, "bulk rx status %d\n", urb->status);

	/* calling tty_flip_buffer_push() in_irq() isn't allowed */
	tasklet_schedule(&acm->bh);
}

static void acm_rx_tasklet(unsigned long _acm)
{
	struct acm *acm = (void *)_acm;
	struct urb *urb = acm->readurb;
	struct tty_struct *tty = acm->tty;
	unsigned char *data = urb->transfer_buffer;
	int i = 0;
	dbg("Entering acm_rx_tasklet");

	if (urb->actual_length > 0 && !acm->throttle)  {
		for (i = 0; i < urb->actual_length && !acm->throttle; i++) {
			/* if we insert more than TTY_FLIPBUF_SIZE characters,
			 * we drop them. */
			if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
				tty_flip_buffer_push(tty);
			}
			tty_insert_flip_char(tty, data[i], 0);
		}
		dbg("Handed %d bytes to tty layer", i+1);
		tty_flip_buffer_push(tty);
	}

	spin_lock(&acm->throttle_lock);
	if (acm->throttle) {
		dbg("Throtteling noticed");
		memmove(data, data + i, urb->actual_length - i);
		urb->actual_length -= i;
		acm->resubmit_to_unthrottle = 1;
		spin_unlock(&acm->throttle_lock);
		return;
	}
	spin_unlock(&acm->throttle_lock);

	urb->actual_length = 0;
	urb->dev = acm->dev;

	i = usb_submit_urb(urb, GFP_ATOMIC);
	if (i)
		dev_dbg(&acm->data->dev, "bulk rx resubmit %d\n", i);
}

/* data interface wrote those outgoing bytes */
static void acm_write_bulk(struct urb *urb, struct pt_regs *regs)
{
	struct acm *acm = (struct acm *)urb->context;
	dbg("Entering acm_write_bulk with status %d\n", urb->status);

	if (!ACM_READY(acm))
		goto out;

	if (urb->status)
		dbg("nonzero write bulk status received: %d", urb->status);

	schedule_work(&acm->work);
out:
	acm->ready_for_write = 1;
}

static void acm_softint(void *private)
{
	struct acm *acm = private;
	dbg("Entering acm_softint.\n");
	
	if (!ACM_READY(acm))
		return;
	tty_wakeup(acm->tty);
}

/*
 * TTY handlers
 */

static int acm_tty_open(struct tty_struct *tty, struct file *filp)
{
	struct acm *acm;
	int rv = -EINVAL;
	dbg("Entering acm_tty_open.\n");
	
	down(&open_sem);

	acm = acm_table[tty->index];
	if (!acm || !acm->dev)
		goto err_out;
	else
		rv = 0;

	tty->driver_data = acm;
	acm->tty = tty;



	if (acm->used++) {
		goto done;
        }

	acm->ctrlurb->dev = acm->dev;
	if (usb_submit_urb(acm->ctrlurb, GFP_KERNEL)) {
		dbg("usb_submit_urb(ctrl irq) failed");
		goto bail_out;
	}

	acm->readurb->dev = acm->dev;
	if (usb_submit_urb(acm->readurb, GFP_KERNEL)) {
		dbg("usb_submit_urb(read bulk) failed");
		goto bail_out_and_unlink;
	}

	if (0 > acm_set_control(acm, acm->ctrlout = ACM_CTRL_DTR | ACM_CTRL_RTS))
		goto full_bailout;

	/* force low_latency on so that our tty_push actually forces the data through, 
	   otherwise it is scheduled, and with high data rates data can get lost. */
	tty->low_latency = 1;

done:
err_out:
	up(&open_sem);
	return rv;

full_bailout:
	usb_kill_urb(acm->readurb);
bail_out_and_unlink:
	usb_kill_urb(acm->ctrlurb);
bail_out:
	acm->used--;
	up(&open_sem);
	return -EIO;
}

static void acm_tty_close(struct tty_struct *tty, struct file *filp)
{
	struct acm *acm = tty->driver_data;

	if (!acm || !acm->used)
		return;

	down(&open_sem);
	if (!--acm->used) {
		if (acm->dev) {
			acm_set_control(acm, acm->ctrlout = 0);
			usb_kill_urb(acm->ctrlurb);
			usb_kill_urb(acm->writeurb);
			usb_kill_urb(acm->readurb);
		} else {
			tty_unregister_device(acm_tty_driver, acm->minor);
			acm_table[acm->minor] = NULL;
			usb_free_urb(acm->ctrlurb);
			usb_free_urb(acm->readurb);
			usb_free_urb(acm->writeurb);
			kfree(acm);
		}
	}
	up(&open_sem);
}

static int acm_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
{
	struct acm *acm = tty->driver_data;
	int stat;
	dbg("Entering acm_tty_write to write %d bytes,\n", count);

	if (!ACM_READY(acm))
		return -EINVAL;
	if (!acm->ready_for_write)
		return 0;
	if (!count)
		return 0;

	count = (count > acm->writesize) ? acm->writesize : count;

	dbg("Get %d bytes...", count);
	memcpy(acm->write_buffer, buf, count);
	dbg("  Successfully copied.\n");

	acm->writeurb->transfer_buffer_length = count;
	acm->writeurb->dev = acm->dev;

	acm->ready_for_write = 0;
	stat = usb_submit_urb(acm->writeurb, GFP_ATOMIC);
	if (stat < 0) {
		dbg("usb_submit_urb(write bulk) failed");
		acm->ready_for_write = 1;
		return stat;
	}

	return count;
}

static int acm_tty_write_room(struct tty_struct *tty)
{
	struct acm *acm = tty->driver_data;
	if (!ACM_READY(acm))
		return -EINVAL;
	return !acm->ready_for_write ? 0 : acm->writesize;
}

static int acm_tty_chars_in_buffer(struct tty_struct *tty)
{
	struct acm *acm = tty->driver_data;
	if (!ACM_READY(acm))
		return -EINVAL;
	return !acm->ready_for_write ? acm->writeurb->transfer_buffer_length : 0;
}

static void acm_tty_throttle(struct tty_struct *tty)
{
	struct acm *acm = tty->driver_data;
	if (!ACM_READY(acm))
		return;
	spin_lock_bh(&acm->throttle_lock);
	acm->throttle = 1;
	spin_unlock_bh(&acm->throttle_lock);
}

static void acm_tty_unthrottle(struct tty_struct *tty)
{
	struct acm *acm = tty->driver_data;
	if (!ACM_READY(acm))
		return;
	spin_lock_bh(&acm->throttle_lock);
	acm->throttle = 0;
	spin_unlock_bh(&acm->throttle_lock);
	if (acm->resubmit_to_unthrottle) {
		acm->resubmit_to_unthrottle = 0;
		acm_read_bulk(acm->readurb, NULL);
	}
}

static void acm_tty_break_ctl(struct tty_struct *tty, int state)
{
	struct acm *acm = tty->driver_data;
	if (!ACM_READY(acm))
		return;
	if (acm_send_break(acm, state ? 0xffff : 0))
		dbg("send break failed");
}

static int acm_tty_tiocmget(struct tty_struct *tty, struct file *file)
{
	struct acm *acm = tty->driver_data;

	if (!ACM_READY(acm))
		return -EINVAL;

	return (acm->ctrlout & ACM_CTRL_DTR ? TIOCM_DTR : 0) |
	       (acm->ctrlout & ACM_CTRL_RTS ? TIOCM_RTS : 0) |
	       (acm->ctrlin  & ACM_CTRL_DSR ? TIOCM_DSR : 0) |
	       (acm->ctrlin  & ACM_CTRL_RI  ? TIOCM_RI  : 0) |
	       (acm->ctrlin  & ACM_CTRL_DCD ? TIOCM_CD  : 0) |
	       TIOCM_CTS;
}

static int acm_tty_tiocmset(struct tty_struct *tty, struct file *file,
			    unsigned int set, unsigned int clear)
{
	struct acm *acm = tty->driver_data;
	unsigned int newctrl;

	if (!ACM_READY(acm))
		return -EINVAL;

	newctrl = acm->ctrlout;
	set = (set & TIOCM_DTR ? ACM_CTRL_DTR : 0) | (set & TIOCM_RTS ? ACM_CTRL_RTS : 0);
	clear = (clear & TIOCM_DTR ? ACM_CTRL_DTR : 0) | (clear & TIOCM_RTS ? ACM_CTRL_RTS : 0);

	newctrl = (newctrl & ~clear) | set;

	if (acm->ctrlout == newctrl)
		return 0;
	return acm_set_control(acm, acm->ctrlout = newctrl);
}

static int acm_tty_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned long arg)
{
	struct acm *acm = tty->driver_data;