linux/drivers/isdn/gigaset/interface.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * interface to user space for the gigaset driver
 *
 * Copyright (c) 2004 by Hansjoerg Lipp <hjlipp@web.de>
 *
 * =====================================================================
 * =====================================================================
 */

#include "gigaset.h"
#include <linux/gigaset_dev.h>
#include <linux/tty_flip.h>
#include <linux/module.h>

/*** our ioctls ***/

static int if_lock(struct cardstate *cs, int *arg)
{
	int cmd = *arg;

	gig_dbg(DEBUG_IF, "%u: if_lock (%d)", cs->minor_index, cmd);

	if (cmd > 1)
		return -EINVAL;

	if (cmd < 0) {
		*arg = cs->mstate == MS_LOCKED;
		return 0;
	}

	if (!cmd && cs->mstate == MS_LOCKED && cs->connected) {
		cs->ops->set_modem_ctrl(cs, 0, TIOCM_DTR | TIOCM_RTS);
		cs->ops->baud_rate(cs, B115200);
		cs->ops->set_line_ctrl(cs, CS8);
		cs->control_state = TIOCM_DTR | TIOCM_RTS;
	}

	cs->waiting = 1;
	if (!gigaset_add_event(cs, &cs->at_state, EV_IF_LOCK,
			       NULL, cmd, NULL)) {
		cs->waiting = 0;
		return -ENOMEM;
	}
	gigaset_schedule_event(cs);

	wait_event(cs->waitqueue, !cs->waiting);

	if (cs->cmd_result >= 0) {
		*arg = cs->cmd_result;
		return 0;
	}

	return cs->cmd_result;
}

static int if_version(struct cardstate *cs, unsigned arg[4])
{
	static const unsigned version[4] = GIG_VERSION;
	static const unsigned compat[4] = GIG_COMPAT;
	unsigned cmd = arg[0];

	gig_dbg(DEBUG_IF, "%u: if_version (%d)", cs->minor_index, cmd);

	switch (cmd) {
	case GIGVER_DRIVER:
		memcpy(arg, version, sizeof version);
		return 0;
	case GIGVER_COMPAT:
		memcpy(arg, compat, sizeof compat);
		return 0;
	case GIGVER_FWBASE:
		cs->waiting = 1;
		if (!gigaset_add_event(cs, &cs->at_state, EV_IF_VER,
				       NULL, 0, arg)) {
			cs->waiting = 0;
			return -ENOMEM;
		}
		gigaset_schedule_event(cs);

		wait_event(cs->waitqueue, !cs->waiting);

		if (cs->cmd_result >= 0)
			return 0;

		return cs->cmd_result;
	default:
		return -EINVAL;
	}
}

static int if_config(struct cardstate *cs, int *arg)
{
	gig_dbg(DEBUG_IF, "%u: if_config (%d)", cs->minor_index, *arg);

	if (*arg != 1)
		return -EINVAL;

	if (cs->mstate != MS_LOCKED)
		return -EBUSY;

	if (!cs->connected) {
		pr_err("%s: not connected\n", __func__);
		return -ENODEV;
	}

	*arg = 0;
	return gigaset_enterconfigmode(cs);
}

/*** the terminal driver ***/

static int if_open(struct tty_struct *tty, struct file *filp)
{
	struct cardstate *cs;

	gig_dbg(DEBUG_IF, "%d+%d: %s()",
		tty->driver->minor_start, tty->index, __func__);

	cs = gigaset_get_cs_by_tty(tty);
	if (!cs || !try_module_get(cs->driver->owner))
		return -ENODEV;

	if (mutex_lock_interruptible(&cs->mutex)) {
		module_put(cs->driver->owner);
		return -ERESTARTSYS;
	}
	tty->driver_data = cs;

	++cs->port.count;

	if (cs->port.count == 1) {
		tty_port_tty_set(&cs->port, tty);
		cs->port.low_latency = 1;
	}

	mutex_unlock(&cs->mutex);
	return 0;
}

static void if_close(struct tty_struct *tty, struct file *filp)
{
	struct cardstate *cs = tty->driver_data;

	if (!cs) { /* happens if we didn't find cs in open */
		gig_dbg(DEBUG_IF, "%s: no cardstate", __func__);
		return;
	}

	gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);

	mutex_lock(&cs->mutex);

	if (!cs->connected)
		gig_dbg(DEBUG_IF, "not connected");	/* nothing to do */
	else if (!cs->port.count)
		dev_warn(cs->dev, "%s: device not opened\n", __func__);
	else if (!--cs->port.count)
		tty_port_tty_set(&cs->port, NULL);

	mutex_unlock(&cs->mutex);

	module_put(cs->driver->owner);
}

static int if_ioctl(struct tty_struct *tty,
		    unsigned int cmd, unsigned long arg)
{
	struct cardstate *cs = tty->driver_data;
	int retval = -ENODEV;
	int int_arg;
	unsigned char buf[6];
	unsigned version[4];

	gig_dbg(DEBUG_IF, "%u: %s(0x%x)", cs->minor_index, __func__, cmd);

	if (mutex_lock_interruptible(&cs->mutex))
		return -ERESTARTSYS;

	if (!cs->connected) {
		gig_dbg(DEBUG_IF, "not connected");
		retval = -ENODEV;
	} else {
		retval = 0;
		switch (cmd) {
		case GIGASET_REDIR:
			retval = get_user(int_arg, (int __user *) arg);
			if (retval >= 0)
				retval = if_lock(cs, &int_arg);
			if (retval >= 0)
				retval = put_user(int_arg, (int __user *) arg);
			break;
		case GIGASET_CONFIG:
			retval = get_user(int_arg, (int __user *) arg);
			if (retval >= 0)
				retval = if_config(cs, &int_arg);
			if (retval >= 0)
				retval = put_user(int_arg, (int __user *) arg);
			break;
		case GIGASET_BRKCHARS:
			retval = copy_from_user(&buf,
						(const unsigned char __user *) arg, 6)
				? -EFAULT : 0;
			if (retval >= 0) {
				gigaset_dbg_buffer(DEBUG_IF, "GIGASET_BRKCHARS",
						   6, buf);
				retval = cs->ops->brkchars(cs, buf);
			}
			break;
		case GIGASET_VERSION:
			retval = copy_from_user(version,
						(unsigned __user *) arg, sizeof version)
				? -EFAULT : 0;
			if (retval >= 0)
				retval = if_version(cs, version);
			if (retval >= 0)
				retval = copy_to_user((unsigned __user *) arg,
						      version, sizeof version)
					? -EFAULT : 0;
			break;
		default:
			gig_dbg(DEBUG_IF, "%s: arg not supported - 0x%04x",
				__func__, cmd);
			retval = -ENOIOCTLCMD;
		}
	}

	mutex_unlock(&cs->mutex);

	return retval;
}

#ifdef CONFIG_COMPAT
static long if_compat_ioctl(struct tty_struct *tty,
		    unsigned int cmd, unsigned long arg)
{
	return if_ioctl(tty, cmd, (unsigned long)compat_ptr(arg));
}
#endif

static int if_tiocmget(struct tty_struct *tty)
{
	struct cardstate *cs = tty->driver_data;
	int retval;

	gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);

	if (mutex_lock_interruptible(&cs->mutex))
		return -ERESTARTSYS;

	retval = cs->control_state & (TIOCM_RTS | TIOCM_DTR);

	mutex_unlock(&cs->mutex);

	return retval;
}

static int if_tiocmset(struct tty_struct *tty,
		       unsigned int set, unsigned int clear)
{
	struct cardstate *cs = tty->driver_data;
	int retval;
	unsigned mc;

	gig_dbg(DEBUG_IF, "%u: %s(0x%x, 0x%x)",
		cs->minor_index, __func__, set, clear);

	if (mutex_lock_interruptible(&cs->mutex))
		return -ERESTARTSYS;

	if (!cs->connected) {
		gig_dbg(DEBUG_IF, "not connected");
		retval = -ENODEV;
	} else {
		mc = (cs->control_state | set) & ~clear & (TIOCM_RTS | TIOCM_DTR);
		retval = cs->ops->set_modem_ctrl(cs, cs->control_state, mc);
		cs->control_state = mc;
	}

	mutex_unlock(&cs->mutex);

	return retval;
}

static int if_write(struct tty_struct *tty, const unsigned char *buf, int count)
{
	struct cardstate *cs = tty->driver_data;
	struct cmdbuf_t *cb;
	int retval;

	gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);

	if (mutex_lock_interruptible(&cs->mutex))
		return -ERESTARTSYS;

	if (!cs->connected) {
		gig_dbg(DEBUG_IF, "not connected");
		retval = -ENODEV;
		goto done;
	}
	if (cs->mstate != MS_LOCKED) {
		dev_warn(cs->dev, "can't write to unlocked device\n");
		retval = -EBUSY;
		goto done;
	}
	if (count <= 0) {
		/* nothing to do */
		retval = 0;
		goto done;
	}

	cb = kmalloc(sizeof(struct cmdbuf_t) + count, GFP_KERNEL);
	if (!cb) {
		dev_err(cs->dev, "%s: out of memory\n", __func__);
		retval = -ENOMEM;
		goto done;
	}

	memcpy(cb->buf, buf, count);
	cb->len = count;
	cb->offset = 0;
	cb->next = NULL;
	cb->wake_tasklet = &cs->if_wake_tasklet;
	retval = cs->ops->write_cmd(cs, cb);
done:
	mutex_unlock(&cs->mutex);
	return retval;
}

static int if_write_room(struct tty_struct *tty)
{
	struct cardstate *cs = tty->driver_data;
	int retval;

	gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);

	if (mutex_lock_interruptible(&cs->mutex))
		return -ERESTARTSYS;

	if (!cs->connected) {
		gig_dbg(DEBUG_IF, "not connected");
		retval = -ENODEV;
	} else if (cs->mstate != MS_LOCKED) {
		dev_warn(cs->dev, "can't write to unlocked device\n");
		retval = -EBUSY;
	} else
		retval = cs->ops->write_room(cs);

	mutex_unlock(&cs->mutex);

	return retval;
}

static int if_chars_in_buffer(struct tty_struct *tty)
{
	struct cardstate *cs = tty->driver_data;
	int retval = 0;

	gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);

	mutex_lock(&cs->mutex);

	if (!cs->connected)
		gig_dbg(DEBUG_IF, "not connected");
	else if (cs->mstate != MS_LOCKED)
		dev_warn(cs->dev, "can't write to unlocked device\n");
	else
		retval = cs->ops->chars_in_buffer(cs);

	mutex_unlock(&cs->mutex);

	return retval;
}

static void if_throttle(struct tty_struct *tty)
{
	struct cardstate *cs = tty->driver_data;

	gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);

	mutex_lock(&cs->mutex);

	if (!cs->connected)
		gig_dbg(DEBUG_IF, "not connected");	/* nothing to do */
	else
		gig_dbg(DEBUG_IF, "%s: not implemented\n", __func__);

	mutex_unlock(&cs->mutex);
}

static void if_unthrottle(struct tty_struct *tty)
{
	struct cardstate *cs = tty->driver_data;

	gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);

	mutex_lock(&cs->mutex);

	if (!cs->connected)
		gig_dbg(DEBUG_IF, "not connected");	/* nothing to do */
	else
		gig_dbg(DEBUG_IF, "%s: not implemented\n", __func__);

	mutex_unlock(&cs->mutex);
}

static void if_set_termios(struct tty_struct *tty, struct ktermios *old)
{
	struct cardstate *cs = tty->driver_data;
	unsigned int iflag;
	unsigned int cflag;
	unsigned int old_cflag;
	unsigned int control_state, new_state;

	gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);

	mutex_lock(&cs->mutex);

	if (!cs->connected) {
		gig_dbg(DEBUG_IF, "not connected");
		goto out;
	}

	iflag = tty->termios.c_iflag;
	cflag = tty->termios.c_cflag;
	old_cflag = old ? old->c_cflag : cflag;
	gig_dbg(DEBUG_IF, "%u: iflag %x cflag %x old %x",
		cs->minor_index, iflag, cflag, old_cflag);

	/* get a local copy of the current port settings */
	control_state = cs->control_state;

	/*
	 * Update baud rate.
	 * Do not attempt to cache old rates and skip settings,
	 * disconnects screw such tricks up completely.
	 * Premature optimization is the root of all evil.
	 */

	/* reassert DTR and (maybe) RTS on transition from B0 */
	if ((old_cflag & CBAUD) == B0) {
		new_state = control_state | TIOCM_DTR;
		/* don't set RTS if using hardware flow control */
		if (!(old_cflag & CRTSCTS))
			new_state |= TIOCM_RTS;
		gig_dbg(DEBUG_IF, "%u: from B0 - set DTR%s",
			cs->minor_index,
			(new_state & TIOCM_RTS) ? " only" : "/RTS");
		cs->ops->set_modem_ctrl(cs, control_state, new_state);
		control_state = new_state;
	}

	cs->ops->baud_rate(cs, cflag & CBAUD);

	if ((cflag & CBAUD) == B0) {
		/* Drop RTS and DTR */
		gig_dbg(DEBUG_IF, "%u: to B0 - drop DTR/RTS", cs->minor_index);
		new_state = control_state & ~(TIOCM_DTR | TIOCM_RTS);
		cs->ops->set_modem_ctrl(cs, control_state, new_state);
		control_state = new_state;
	}

	/*
	 * Update line control register (LCR)
	 */

	cs->ops->set_line_ctrl(cs, cflag);

	/* save off the modified port settings */
	cs->control_state = control_state;

out:
	mutex_unlock(&cs->mutex);
}

static const struct tty_operations if_ops = {
	.open =			if_open,
	.close =		if_close,
	.ioctl =		if_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl =		if_compat_ioctl,
#endif
	.write =		if_write,
	.write_room =		if_write_room,
	.chars_in_buffer =	if_chars_in_buffer,
	.set_termios =		if_set_termios,
	.throttle =		if_throttle,
	.unthrottle =		if_unthrottle,
	.tiocmget =		if_tiocmget,
	.tiocmset =		if_tiocmset,
};


/* wakeup tasklet for the write operation */
static void if_wake(unsigned long data)
{
	struct cardstate *cs = (struct cardstate *)data;

	tty_port_tty_wakeup(&cs->port);
}

/*** interface to common ***/

void gigaset_if_init(struct cardstate *cs)
{
	struct gigaset_driver *drv;

	drv = cs->driver;
	if (!drv->have_tty)
		return;

	tasklet_init(&cs->if_wake_tasklet, if_wake, (unsigned long) cs);

	mutex_lock(&cs->mutex);
	cs->tty_dev = tty_port_register_device(&cs->port, drv->tty,
			cs->minor_index, NULL);

	if (!IS_ERR(cs->tty_dev))
		dev_set_drvdata(cs->tty_dev, cs);
	else {
		pr_warning("could not register device to the tty subsystem\n");
		cs->tty_dev = NULL;
	}
	mutex_unlock(&cs->mutex);
}

void gigaset_if_free(struct cardstate *cs)
{
	struct gigaset_driver *drv;

	drv = cs->driver;
	if (!drv->have_tty)
		return;

	tasklet_disable(&cs->if_wake_tasklet);
	tasklet_kill(&cs->if_wake_tasklet);
	cs->tty_dev = NULL;
	tty_unregister_device(drv->tty, cs->minor_index);
}

/**
 * gigaset_if_receive() - pass a received block of data to the tty device
 * @cs:		device descriptor structure.
 * @buffer:	received data.
 * @len:	number of bytes received.
 *
 * Called by asyncdata/isocdata if a block of data received from the
 * device must be sent to userspace through the ttyG* device.
 */
void gigaset_if_receive(struct cardstate *cs,
			unsigned char *buffer, size_t len)
{
	tty_insert_flip_string(&cs->port, buffer, len);
	tty_flip_buffer_push(&cs->port);
}
EXPORT_SYMBOL_GPL(gigaset_if_receive);

/* gigaset_if_initdriver
 * Initialize tty interface.
 * parameters:
 *	drv		Driver
 *	procname	Name of the driver (e.g. for /proc/tty/drivers)
 *	devname		Name of the device files (prefix without minor number)
 */
void gigaset_if_initdriver(struct gigaset_driver *drv, const char *procname,
			   const char *devname)
{
	int ret;
	struct tty_driver *tty;

	drv->have_tty = 0;

	drv->tty = tty = alloc_tty_driver(drv->minors);
	if (tty == NULL)
		goto enomem;

	tty->type =		TTY_DRIVER_TYPE_SERIAL;
	tty->subtype =		SERIAL_TYPE_NORMAL;
	tty->flags =		TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;

	tty->driver_name =	procname;
	tty->name =		devname;
	tty->minor_start =	drv->minor;

	tty->init_termios          = tty_std_termios;
	tty->init_termios.c_cflag  = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
	tty_set_operations(tty, &if_ops);

	ret = tty_register_driver(tty);
	if (ret < 0) {
		pr_err("error %d registering tty driver\n", ret);
		goto error;
	}
	gig_dbg(DEBUG_IF, "tty driver initialized");
	drv->have_tty = 1;
	return;

enomem:
	pr_err("out of memory\n");
error:
	if (drv->tty)
		put_tty_driver(drv->tty);
}

void gigaset_if_freedriver(struct gigaset_driver *drv)
{
	if (!drv->have_tty)
		return;

	drv->have_tty = 0;
	tty_unregister_driver(drv->tty);
	put_tty_driver(drv->tty);
}