[PATCH] drivers/isdn/gigaset: new M101 driver (v2)

This patch adds the line discipline based driver for the Gigaset M101
wireless RS232 adapter. It also improves the documentation a bit.

Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: Hansjoerg Lipp <hjlipp@web.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

6 files changed, 868 insertions, 23 deletions

diff --git a/drivers/isdn/gigaset/Kconfig b/drivers/isdn/gigaset/Kconfig
index 708d47a6484..bcbb6502a77 100644
--- a/drivers/isdn/gigaset/Kconfig
+++ b/drivers/isdn/gigaset/Kconfig
@@ -7,7 +7,13 @@ config ISDN_DRV_GIGASET
 	select CRC_CCITT
 	select BITREVERSE
 	help
-	  Say m here if you have a Gigaset or Sinus isdn device.
+	  This driver supports the Siemens Gigaset SX205/255 family of
+	  ISDN DECT bases, including the predecessors Gigaset 3070/3075
+	  and 4170/4175 and their T-Com versions Sinus 45isdn and Sinus
+	  721X.
+	  If you have one of these devices, say M here and for at least
+	  one of the connection specific parts that follow.
+	  This will build a module called "gigaset".
 
 if ISDN_DRV_GIGASET!=n
 
@@ -15,14 +21,25 @@ config GIGASET_BASE
 	tristate "Gigaset base station support"
 	depends on ISDN_DRV_GIGASET && USB
 	help
-	  Say m here if you need to communicate with the base
-	  directly via USB.
+	  Say M here if you want to use the USB interface of the Gigaset
+	  base for connection to your system.
+	  This will build a module called "bas_gigaset".
 
 config GIGASET_M105
 	tristate "Gigaset M105 support"
 	depends on ISDN_DRV_GIGASET && USB
 	help
-	  Say m here if you need the driver for the Gigaset M105 device.
+	  Say M here if you want to connect to the Gigaset base via DECT
+	  using a Gigaset M105 (Sinus 45 Data 2) USB DECT device.
+	  This will build a module called "usb_gigaset".
+
+config GIGASET_M101
+	tristate "Gigaset M101 support"
+	depends on ISDN_DRV_GIGASET
+	help
+	  Say M here if you want to connect to the Gigaset base via DECT
+	  using a Gigaset M101 (Sinus 45 Data 1) RS232 DECT device.
+	  This will build a module called "ser_gigaset".
 
 config GIGASET_DEBUG
 	bool "Gigaset debugging"
diff --git a/drivers/isdn/gigaset/Makefile b/drivers/isdn/gigaset/Makefile
index 9b9acf1a21a..835b806a9de 100644
--- a/drivers/isdn/gigaset/Makefile
+++ b/drivers/isdn/gigaset/Makefile
@@ -1,6 +1,8 @@
 gigaset-y := common.o interface.o proc.o ev-layer.o i4l.o
 usb_gigaset-y := usb-gigaset.o asyncdata.o
 bas_gigaset-y := bas-gigaset.o isocdata.o
+ser_gigaset-y := ser-gigaset.o asyncdata.o
 
 obj-$(CONFIG_GIGASET_M105) += usb_gigaset.o gigaset.o
 obj-$(CONFIG_GIGASET_BASE) += bas_gigaset.o gigaset.o
+obj-$(CONFIG_GIGASET_M105) += ser_gigaset.o gigaset.o
diff --git a/drivers/isdn/gigaset/asyncdata.c b/drivers/isdn/gigaset/asyncdata.c
index 88e958f176d..ddf5e92be44 100644
--- a/drivers/isdn/gigaset/asyncdata.c
+++ b/drivers/isdn/gigaset/asyncdata.c
@@ -13,6 +13,11 @@
  * =====================================================================
  */
 
+/* not set by Kbuild when building both ser_gigaset and usb_gigaset */
+#ifndef KBUILD_MODNAME
+#define KBUILD_MODNAME "asy_gigaset"
+#endif
+
 #include "gigaset.h"
 #include <linux/crc-ccitt.h>
 #include <linux/bitrev.h>
diff --git a/drivers/isdn/gigaset/common.c b/drivers/isdn/gigaset/common.c
index 9d4ae04eb33..b460a73a7c8 100644
--- a/drivers/isdn/gigaset/common.c
+++ b/drivers/isdn/gigaset/common.c
@@ -906,20 +906,7 @@ void gigaset_shutdown(struct cardstate *cs)
 	gig_dbg(DEBUG_CMD, "scheduling SHUTDOWN");
 	gigaset_schedule_event(cs);
 
-	if (wait_event_interruptible(cs->waitqueue, !cs->waiting)) {
-		warn("%s: aborted", __func__);
-		//FIXME
-	}
-
-	if (atomic_read(&cs->mstate) != MS_LOCKED) {
-		//FIXME?
-		//gigaset_baud_rate(cs, B115200);
-		//gigaset_set_line_ctrl(cs, CS8);
-		//gigaset_set_modem_ctrl(cs, TIOCM_DTR|TIOCM_RTS, 0);
-		//cs->control_state = 0;
-	} else {
-		//FIXME use some saved values?
-	}
+	wait_event(cs->waitqueue, !cs->waiting);
 
 	cleanup_cs(cs);
 
@@ -942,10 +929,7 @@ void gigaset_stop(struct cardstate *cs)
 	gig_dbg(DEBUG_CMD, "scheduling STOP");
 	gigaset_schedule_event(cs);
 
-	if (wait_event_interruptible(cs->waitqueue, !cs->waiting)) {
-		warn("%s: aborted", __func__);
-		//FIXME
-	}
+	wait_event(cs->waitqueue, !cs->waiting);
 
 	cleanup_cs(cs);
 
diff --git a/drivers/isdn/gigaset/ev-layer.c b/drivers/isdn/gigaset/ev-layer.c
index 44f02dbd111..4661e2c722b 100644
--- a/drivers/isdn/gigaset/ev-layer.c
+++ b/drivers/isdn/gigaset/ev-layer.c
@@ -1015,7 +1015,7 @@ static void finish_shutdown(struct cardstate *cs)
 
 	cs->cmd_result = -ENODEV;
 	cs->waiting = 0;
-	wake_up_interruptible(&cs->waitqueue);
+	wake_up(&cs->waitqueue);
 }
 
 static void do_shutdown(struct cardstate *cs)
diff --git a/drivers/isdn/gigaset/ser-gigaset.c b/drivers/isdn/gigaset/ser-gigaset.c
new file mode 100644
index 00000000000..c8b7db65e48
--- /dev/null
+++ b/drivers/isdn/gigaset/ser-gigaset.c
@@ -0,0 +1,837 @@
+/* This is the serial hardware link layer (HLL) for the Gigaset 307x isdn
+ * DECT base (aka Sinus 45 isdn) using the RS232 DECT data module M101,
+ * written as a line discipline.
+ *
+ * =====================================================================
+ * 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.
+ * =====================================================================
+ */
+
+#include "gigaset.h"
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/platform_device.h>
+#include <linux/tty.h>
+#include <linux/poll.h>
+
+/* Version Information */
+#define DRIVER_AUTHOR "Tilman Schmidt"
+#define DRIVER_DESC "Serial Driver for Gigaset 307x using Siemens M101"
+
+#define GIGASET_MINORS     1
+#define GIGASET_MINOR      0
+#define GIGASET_MODULENAME "ser_gigaset"
+#define GIGASET_DEVNAME    "ttyGS"
+
+/* length limit according to Siemens 3070usb-protokoll.doc ch. 2.1 */
+#define IF_WRITEBUF 264
+
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_LDISC(N_GIGASET_M101);
+
+static int startmode = SM_ISDN;
+module_param(startmode, int, S_IRUGO);
+MODULE_PARM_DESC(startmode, "initial operation mode");
+static int cidmode = 1;
+module_param(cidmode, int, S_IRUGO);
+MODULE_PARM_DESC(cidmode, "stay in CID mode when idle");
+
+static struct gigaset_driver *driver;
+
+struct ser_cardstate {
+	struct platform_device	dev;
+	struct tty_struct	*tty;
+	atomic_t		refcnt;
+	struct mutex		dead_mutex;
+};
+
+static struct platform_driver device_driver = {
+	.driver = {
+		.name = GIGASET_MODULENAME,
+	},
+};
+
+static void flush_send_queue(struct cardstate *);
+
+/* transmit data from current open skb
+ * result: number of bytes sent or error code < 0
+ */
+static int write_modem(struct cardstate *cs)
+{
+	struct tty_struct *tty = cs->hw.ser->tty;
+	struct bc_state *bcs = &cs->bcs[0];	/* only one channel */
+	struct sk_buff *skb = bcs->tx_skb;
+	int sent;
+
+	if (!tty || !tty->driver || !skb)
+		return -EFAULT;
+
+	if (!skb->len) {
+		dev_kfree_skb_any(skb);
+		bcs->tx_skb = NULL;
+		return -EINVAL;
+	}
+
+	set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+	sent = tty->driver->write(tty, skb->data, skb->len);
+	gig_dbg(DEBUG_OUTPUT, "write_modem: sent %d", sent);
+	if (sent < 0) {
+		/* error */
+		flush_send_queue(cs);
+		return sent;
+	}
+	skb_pull(skb, sent);
+	if (!skb->len) {
+		/* skb sent completely */
+		gigaset_skb_sent(bcs, skb);
+
+		gig_dbg(DEBUG_INTR, "kfree skb (Adr: %lx)!",
+			(unsigned long) skb);
+		dev_kfree_skb_any(skb);
+		bcs->tx_skb = NULL;
+	}
+	return sent;
+}
+
+/*
+ * transmit first queued command buffer
+ * result: number of bytes sent or error code < 0
+ */
+static int send_cb(struct cardstate *cs)
+{
+	struct tty_struct *tty = cs->hw.ser->tty;
+	struct cmdbuf_t *cb, *tcb;
+	unsigned long flags;
+	int sent = 0;
+
+	if (!tty || !tty->driver)
+		return -EFAULT;
+
+	cb = cs->cmdbuf;
+	if (!cb)
+		return 0;	/* nothing to do */
+
+	if (cb->len) {
+		set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+		sent = tty->driver->write(tty, cb->buf + cb->offset, cb->len);
+		if (sent < 0) {
+			/* error */
+			gig_dbg(DEBUG_OUTPUT, "send_cb: write error %d", sent);
+			flush_send_queue(cs);
+			return sent;
+		}
+		cb->offset += sent;
+		cb->len -= sent;
+		gig_dbg(DEBUG_OUTPUT, "send_cb: sent %d, left %u, queued %u",
+			sent, cb->len, cs->cmdbytes);
+	}
+
+	while (cb && !cb->len) {
+		spin_lock_irqsave(&cs->cmdlock, flags);
+		cs->cmdbytes -= cs->curlen;
+		tcb = cb;
+		cs->cmdbuf = cb = cb->next;
+		if (cb) {
+			cb->prev = NULL;
+			cs->curlen = cb->len;
+		} else {
+			cs->lastcmdbuf = NULL;
+			cs->curlen = 0;
+		}
+		spin_unlock_irqrestore(&cs->cmdlock, flags);
+
+		if (tcb->wake_tasklet)
+			tasklet_schedule(tcb->wake_tasklet);
+		kfree(tcb);
+	}
+	return sent;
+}
+
+/*
+ * send queue tasklet
+ * If there is already a skb opened, put data to the transfer buffer
+ * by calling "write_modem".
+ * Otherwise take a new skb out of the queue.
+ */
+static void gigaset_modem_fill(unsigned long data)
+{
+	struct cardstate *cs = (struct cardstate *) data;
+	struct bc_state *bcs;
+	int sent = 0;
+
+	if (!cs || !(bcs = cs->bcs)) {
+		gig_dbg(DEBUG_OUTPUT, "%s: no cardstate", __func__);
+		return;
+	}
+	if (!bcs->tx_skb) {
+		/* no skb is being sent; send command if any */
+		sent = send_cb(cs);
+		gig_dbg(DEBUG_OUTPUT, "%s: send_cb -> %d", __func__, sent);
+		if (sent)
+			/* something sent or error */
+			return;
+
+		/* no command to send; get skb */
+		if (!(bcs->tx_skb = skb_dequeue(&bcs->squeue)))
+			/* no skb either, nothing to do */
+			return;
+
+		gig_dbg(DEBUG_INTR, "Dequeued skb (Adr: %lx)",
+			(unsigned long) bcs->tx_skb);
+	}
+
+	/* send skb */
+	gig_dbg(DEBUG_OUTPUT, "%s: tx_skb", __func__);
+	if (write_modem(cs) < 0)
+		gig_dbg(DEBUG_OUTPUT, "%s: write_modem failed", __func__);
+}
+
+/*
+ * throw away all data queued for sending
+ */
+static void flush_send_queue(struct cardstate *cs)
+{
+	struct sk_buff *skb;
+	struct cmdbuf_t *cb;
+	unsigned long flags;
+
+	/* command queue */
+	spin_lock_irqsave(&cs->cmdlock, flags);
+	while ((cb = cs->cmdbuf) != NULL) {
+		cs->cmdbuf = cb->next;
+		if (cb->wake_tasklet)
+			tasklet_schedule(cb->wake_tasklet);
+		kfree(cb);
+	}
+	cs->cmdbuf = cs->lastcmdbuf = NULL;
+	cs->cmdbytes = cs->curlen = 0;
+	spin_unlock_irqrestore(&cs->cmdlock, flags);
+
+	/* data queue */
+	if (cs->bcs->tx_skb)
+		dev_kfree_skb_any(cs->bcs->tx_skb);
+	while ((skb = skb_dequeue(&cs->bcs->squeue)) != NULL)
+		dev_kfree_skb_any(skb);
+}
+
+
+/* Gigaset Driver Interface */
+/* ======================== */
+
+/*
+ * queue an AT command string for transmission to the Gigaset device
+ * parameters:
+ *	cs		controller state structure
+ *	buf		buffer containing the string to send
+ *	len		number of characters to send
+ *	wake_tasklet	tasklet to run when transmission is complete, or NULL
+ * return value:
+ *	number of bytes queued, or error code < 0
+ */
+static int gigaset_write_cmd(struct cardstate *cs, const unsigned char *buf,
+                             int len, struct tasklet_struct *wake_tasklet)
+{
+	struct cmdbuf_t *cb;
+	unsigned long flags;
+
+	gigaset_dbg_buffer(atomic_read(&cs->mstate) != MS_LOCKED ?
+	                     DEBUG_TRANSCMD : DEBUG_LOCKCMD,
+	                   "CMD Transmit", len, buf);
+
+	if (len <= 0)
+		return 0;
+
+	if (!(cb = kmalloc(sizeof(struct cmdbuf_t) + len, GFP_ATOMIC))) {
+		dev_err(cs->dev, "%s: out of memory!\n", __func__);
+		return -ENOMEM;
+	}
+
+	memcpy(cb->buf, buf, len);
+	cb->len = len;
+	cb->offset = 0;
+	cb->next = NULL;
+	cb->wake_tasklet = wake_tasklet;
+
+	spin_lock_irqsave(&cs->cmdlock, flags);
+	cb->prev = cs->lastcmdbuf;
+	if (cs->lastcmdbuf)
+		cs->lastcmdbuf->next = cb;
+	else {
+		cs->cmdbuf = cb;
+		cs->curlen = len;
+	}
+	cs->cmdbytes += len;
+	cs->lastcmdbuf = cb;
+	spin_unlock_irqrestore(&cs->cmdlock, flags);
+
+	spin_lock_irqsave(&cs->lock, flags);
+	if (cs->connected)
+		tasklet_schedule(&cs->write_tasklet);
+	spin_unlock_irqrestore(&cs->lock, flags);
+	return len;
+}
+
+/*
+ * tty_driver.write_room interface routine
+ * return number of characters the driver will accept to be written
+ * parameter:
+ *	controller state structure
+ * return value:
+ *	number of characters
+ */
+static int gigaset_write_room(struct cardstate *cs)
+{
+	unsigned bytes;
+
+	bytes = cs->cmdbytes;
+	return bytes < IF_WRITEBUF ? IF_WRITEBUF - bytes : 0;
+}
+
+/*
+ * tty_driver.chars_in_buffer interface routine
+ * return number of characters waiting to be sent
+ * parameter:
+ *	controller state structure
+ * return value:
+ *	number of characters
+ */
+static int gigaset_chars_in_buffer(struct cardstate *cs)
+{
+	return cs->cmdbytes;
+}
+
+/*
+ * implementation of ioctl(GIGASET_BRKCHARS)
+ * parameter:
+ *	controller state structure
+ * return value:
+ *	-EINVAL (unimplemented function)
+ */
+static int gigaset_brkchars(struct cardstate *cs, const unsigned char buf[6])
+{
+	/* not implemented */
+	return -EINVAL;
+}
+
+/*
+ * Open B channel
+ * Called by "do_action" in ev-layer.c
+ */
+static int gigaset_init_bchannel(struct bc_state *bcs)
+{
+	/* nothing to do for M10x */
+	gigaset_bchannel_up(bcs);
+	return 0;
+}
+
+/*
+ * Close B channel
+ * Called by "do_action" in ev-layer.c
+ */
+static int gigaset_close_bchannel(struct bc_state *bcs)
+{
+	/* nothing to do for M10x */
+	gigaset_bchannel_down(bcs);
+	return 0;
+}
+
+/*
+ * Set up B channel structure
+ * This is called by "gigaset_initcs" in common.c
+ */
+static int gigaset_initbcshw(struct bc_state *bcs)
+{
+	/* unused */
+	bcs->hw.ser = NULL;
+	return 1;
+}
+
+/*
+ * Free B channel structure
+ * Called by "gigaset_freebcs" in common.c
+ */
+static int gigaset_freebcshw(struct bc_state *bcs)
+{
+	/* unused */
+	return 1;
+}
+
+/*
+ * Reinitialize B channel structure
+ * This is called by "bcs_reinit" in common.c
+ */
+static void gigaset_reinitbcshw(struct bc_state *bcs)
+{
+	/* nothing to do for M10x */
+}
+
+/*
+ * Free hardware specific device data
+ * This will be called by "gigaset_freecs" in common.c
+ */
+static void gigaset_freecshw(struct cardstate *cs)
+{
+	tasklet_kill(&cs->write_tasklet);
+	if (!cs->hw.ser)
+		return;
+	dev_set_drvdata(&cs->hw.ser->dev.dev, NULL);
+	platform_device_unregister(&cs->hw.ser->dev);
+	kfree(cs->hw.ser);
+	cs->hw.ser = NULL;
+}
+
+static void gigaset_device_release(struct device *dev)
+{
+	struct platform_device *pdev =
+		container_of(dev, struct platform_device, dev);
+
+	/* adapted from platform_device_release() in drivers/base/platform.c */
+	//FIXME is this actually necessary?
+	kfree(dev->platform_data);
+	kfree(pdev->resource);
+}
+
+/*
+ * Set up hardware specific device data
+ * This is called by "gigaset_initcs" in common.c
+ */
+static int gigaset_initcshw(struct cardstate *cs)
+{
+	int rc;
+
+	if (!(cs->hw.ser = kzalloc(sizeof(struct ser_cardstate), GFP_KERNEL))) {
+		err("%s: out of memory!", __func__);
+		return 0;
+	}
+
+	cs->hw.ser->dev.name = GIGASET_MODULENAME;
+	cs->hw.ser->dev.id = cs->minor_index;
+	cs->hw.ser->dev.dev.release = gigaset_device_release;
+	if ((rc = platform_device_register(&cs->hw.ser->dev)) != 0) {
+		err("error %d registering platform device", rc);
+		kfree(cs->hw.ser);
+		cs->hw.ser = NULL;
+		return 0;
+	}
+	dev_set_drvdata(&cs->hw.ser->dev.dev, cs);
+
+	tasklet_init(&cs->write_tasklet,
+	             &gigaset_modem_fill, (unsigned long) cs);
+	return 1;
+}
+
+/*
+ * set modem control lines
+ * Parameters:
+ *	card state structure
+ *	modem control line state ([TIOCM_DTR]|[TIOCM_RTS])
+ * Called by "gigaset_start" and "gigaset_enterconfigmode" in common.c
+ * and by "if_lock" and "if_termios" in interface.c
+ */
+static int gigaset_set_modem_ctrl(struct cardstate *cs, unsigned old_state, unsigned new_state)
+{
+	struct tty_struct *tty = cs->hw.ser->tty;
+	unsigned int set, clear;
+
+	if (!tty || !tty->driver || !tty->driver->tiocmset)
+		return -EFAULT;
+	set = new_state & ~old_state;
+	clear = old_state & ~new_state;
+	if (!set && !clear)
+		return 0;
+	gig_dbg(DEBUG_IF, "tiocmset set %x clear %x", set, clear);
+	return tty->driver->tiocmset(tty, NULL, set, clear);
+}
+
+static int gigaset_baud_rate(struct cardstate *cs, unsigned cflag)
+{
+	return -EINVAL;
+}
+
+static int gigaset_set_line_ctrl(struct cardstate *cs, unsigned cflag)
+{
+	return -EINVAL;
+}
+
+static struct gigaset_ops ops = {
+	gigaset_write_cmd,
+	gigaset_write_room,
+	gigaset_chars_in_buffer,
+	gigaset_brkchars,
+	gigaset_init_bchannel,
+	gigaset_close_bchannel,
+	gigaset_initbcshw,
+	gigaset_freebcshw,
+	gigaset_reinitbcshw,
+	gigaset_initcshw,
+	gigaset_freecshw,
+	gigaset_set_modem_ctrl,
+	gigaset_baud_rate,
+	gigaset_set_line_ctrl,
+	gigaset_m10x_send_skb,	/* asyncdata.c */
+	gigaset_m10x_input,	/* asyncdata.c */
+};
+
+
+/* Line Discipline Interface */
+/* ========================= */
+
+/* helper functions for cardstate refcounting */
+static struct cardstate *cs_get(struct tty_struct *tty)
+{
+	struct cardstate *cs = tty->disc_data;
+
+	if (!cs || !cs->hw.ser) {
+		gig_dbg(DEBUG_ANY, "%s: no cardstate", __func__);
+		return NULL;
+	}
+	atomic_inc(&cs->hw.ser->refcnt);
+	return cs;
+}
+
+static void cs_put(struct cardstate *cs)
+{
+	if (atomic_dec_and_test(&cs->hw.ser->refcnt))
+		mutex_unlock(&cs->hw.ser->dead_mutex);
+}
+
+/*
+ * Called by the tty driver when the line discipline is pushed onto the tty.
+ * Called in process context.
+ */
+static int
+gigaset_tty_open(struct tty_struct *tty)
+{
+	struct cardstate *cs;
+
+	gig_dbg(DEBUG_INIT, "Starting HLL for Gigaset M101");
+
+	info(DRIVER_AUTHOR);
+	info(DRIVER_DESC);
+
+	if (!driver) {
+		err("%s: no driver structure", __func__);
+		return -ENODEV;
+	}
+
+	/* allocate memory for our device state and intialize it */
+	if (!(cs = gigaset_initcs(driver, 1, 1, 0, cidmode,
+				  GIGASET_MODULENAME)))
+		goto error;
+
+	cs->dev = &cs->hw.ser->dev.dev;
+	cs->hw.ser->tty = tty;
+	mutex_init(&cs->hw.ser->dead_mutex);
+	atomic_set(&cs->hw.ser->refcnt, 1);
+
+	tty->disc_data = cs;
+
+	/* OK.. Initialization of the datastructures and the HW is done.. Now
+	 * startup system and notify the LL that we are ready to run
+	 */
+	if (startmode == SM_LOCKED)
+		atomic_set(&cs->mstate, MS_LOCKED);
+	if (!gigaset_start(cs)) {
+		tasklet_kill(&cs->write_tasklet);
+		goto error;
+	}
+
+	gig_dbg(DEBUG_INIT, "Startup of HLL done");
+	mutex_lock(&cs->hw.ser->dead_mutex);
+	return 0;
+
+error:
+	gig_dbg(DEBUG_INIT, "Startup of HLL failed");
+	tty->disc_data = NULL;
+	gigaset_freecs(cs);
+	return -ENODEV;
+}
+
+/*
+ * Called by the tty driver when the line discipline is removed.
+ * Called from process context.
+ */
+static void
+gigaset_tty_close(struct tty_struct *tty)
+{
+	struct cardstate *cs = tty->disc_data;
+
+	gig_dbg(DEBUG_INIT, "Stopping HLL for Gigaset M101");
+
+	if (!cs) {
+		gig_dbg(DEBUG_INIT, "%s: no cardstate", __func__);
+		return;
+	}
+
+	/* prevent other callers from entering ldisc methods */
+	tty->disc_data = NULL;
+
+	if (!cs->hw.ser)
+		err("%s: no hw cardstate", __func__);
+	else {
+		/* wait for running methods to finish */
+		if (!atomic_dec_and_test(&cs->hw.ser->refcnt))
+			mutex_lock(&cs->hw.ser->dead_mutex);
+	}
+
+	/* stop operations */
+	gigaset_stop(cs);
+	tasklet_kill(&cs->write_tasklet);
+	flush_send_queue(cs);
+	cs->dev = NULL;
+	gigaset_freecs(cs);
+
+	gig_dbg(DEBUG_INIT, "Shutdown of HLL done");
+}
+
+/*
+ * Called by the tty driver when the tty line is hung up.
+ * Wait for I/O to driver to complete and unregister ISDN device.
+ * This is already done by the close routine, so just call that.
+ * Called from process context.
+ */
+static int gigaset_tty_hangup(struct tty_struct *tty)
+{
+	gigaset_tty_close(tty);
+	return 0;
+}
+
+/*
+ * Read on the tty.
+ * Unused, received data goes only to the Gigaset driver.
+ */
+static ssize_t
+gigaset_tty_read(struct tty_struct *tty, struct file *file,
+		 unsigned char __user *buf, size_t count)
+{
+	return -EAGAIN;
+}
+
+/*
+ * Write on the tty.
+ * Unused, transmit data comes only from the Gigaset driver.
+ */
+static ssize_t
+gigaset_tty_write(struct tty_struct *tty, struct file *file,
+		  const unsigned char *buf, size_t count)
+{
+	return -EAGAIN;
+}
+
+/*
+ * Ioctl on the tty.
+ * Called in process context only.
+ * May be re-entered by multiple ioctl calling threads.
+ */
+static int
+gigaset_tty_ioctl(struct tty_struct *tty, struct file *file,
+		  unsigned int cmd, unsigned long arg)
+{
+	struct cardstate *cs = cs_get(tty);
+	int rc, val;
+	int __user *p = (int __user *)arg;
+
+	if (!cs)
+		return -ENXIO;
+
+	switch (cmd) {
+	case TCGETS:
+	case TCGETA:
+		/* pass through to underlying serial device */
+		rc = n_tty_ioctl(tty, file, cmd, arg);
+		break;
+
+	case TCFLSH:
+		/* flush our buffers and the serial port's buffer */
+		switch (arg) {
+		case TCIFLUSH:
+			/* no own input buffer to flush */
+			break;
+		case TCIOFLUSH:
+		case TCOFLUSH:
+			flush_send_queue(cs);
+			break;
+		}
+		/* flush the serial port's buffer */
+		rc = n_tty_ioctl(tty, file, cmd, arg);
+		break;
+
+	case FIONREAD:
+		/* unused, always return zero */
+		val = 0;
+		rc = put_user(val, p);
+		break;
+
+	default:
+		rc = -ENOIOCTLCMD;
+	}
+
+	cs_put(cs);
+	return rc;
+}
+
+/*
+ * Poll on the tty.
+ * Unused, always return zero.
+ */
+static unsigned int
+gigaset_tty_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
+{
+	return 0;
+}
+
+/*
+ * Called by the tty driver when a block of data has been received.
+ * Will not be re-entered while running but other ldisc functions
+ * may be called in parallel.
+ * Can be called from hard interrupt level as well as soft interrupt
+ * level or mainline.
+ * Parameters:
+ *	tty	tty structure
+ *	buf	buffer containing received characters
+ *	cflags	buffer containing error flags for received characters (ignored)
+ *	count	number of received characters
+ */
+static void
+gigaset_tty_receive(struct tty_struct *tty, const unsigned char *buf,
+		    char *cflags, int count)
+{
+	struct cardstate *cs = cs_get(tty);
+	unsigned tail, head, n;
+	struct inbuf_t *inbuf;
+
+	if (!cs)
+		return;
+	if (!(inbuf = cs->inbuf)) {
+		dev_err(cs->dev, "%s: no inbuf\n", __func__);
+		cs_put(cs);
+		return;
+	}
+
+	tail = atomic_read(&inbuf->tail);
+	head = atomic_read(&inbuf->head);
+	gig_dbg(DEBUG_INTR, "buffer state: %u -> %u, receive %u bytes",
+		head, tail, count);
+
+	if (head <= tail) {
+		/* possible buffer wraparound */
+		n = min_t(unsigned, count, RBUFSIZE - tail);
+		memcpy(inbuf->data + tail, buf, n);
+		tail = (tail + n) % RBUFSIZE;
+		buf += n;
+		count -= n;
+	}
+
+	if (count > 0) {
+		/* tail < head and some data left */
+		n = head - tail - 1;
+		if (count > n) {
+			dev_err(cs->dev,
+				"inbuf overflow, discarding %d bytes\n",
+				count - n);
+			count = n;
+		}
+		memcpy(inbuf->data + tail, buf, count);
+		tail += count;
+	}
+
+	gig_dbg(DEBUG_INTR, "setting tail to %u", tail);
+	atomic_set(&inbuf->tail, tail);
+
+	/* Everything was received .. Push data into handler */
+	gig_dbg(DEBUG_INTR, "%s-->BH", __func__);
+	gigaset_schedule_event(cs);
+	cs_put(cs);
+}
+
+/*
+ * Called by the tty driver when there's room for more data to send.
+ */
+static void
+gigaset_tty_wakeup(struct tty_struct *tty)
+{
+	struct cardstate *cs = cs_get(tty);
+
+	clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+	if (!cs)
+		return;
+	tasklet_schedule(&cs->write_tasklet);
+	cs_put(cs);
+}
+
+static struct tty_ldisc gigaset_ldisc = {
+	.owner		= THIS_MODULE,
+	.magic		= TTY_LDISC_MAGIC,
+	.name		= "ser_gigaset",
+	.open		= gigaset_tty_open,
+	.close		= gigaset_tty_close,
+	.hangup		= gigaset_tty_hangup,
+	.read		= gigaset_tty_read,
+	.write		= gigaset_tty_write,
+	.ioctl		= gigaset_tty_ioctl,
+	.poll		= gigaset_tty_poll,
+	.receive_buf	= gigaset_tty_receive,
+	.write_wakeup	= gigaset_tty_wakeup,
+};
+
+
+/* Initialization / Shutdown */
+/* ========================= */
+
+static int __init ser_gigaset_init(void)
+{
+	int rc;
+
+	gig_dbg(DEBUG_INIT, "%s", __func__);
+	if ((rc = platform_driver_register(&device_driver)) != 0) {
+		err("error %d registering platform driver", rc);
+		return rc;
+	}
+
+	/* allocate memory for our driver state and intialize it */
+	if (!(driver = gigaset_initdriver(GIGASET_MINOR, GIGASET_MINORS,
+					  GIGASET_MODULENAME, GIGASET_DEVNAME,
+					  &ops, THIS_MODULE)))
+		goto error;
+
+	if ((rc = tty_register_ldisc(N_GIGASET_M101, &gigaset_ldisc)) != 0) {
+		err("error %d registering line discipline", rc);
+		goto error;
+	}
+
+	return 0;
+
+error:
+	if (driver) {
+		gigaset_freedriver(driver);
+		driver = NULL;
+	}
+	platform_driver_unregister(&device_driver);
+	return rc;
+}
+
+static void __exit ser_gigaset_exit(void)
+{
+	int rc;
+
+	gig_dbg(DEBUG_INIT, "%s", __func__);
+
+	if (driver) {
+		gigaset_freedriver(driver);
+		driver = NULL;
+	}
+
+	if ((rc = tty_unregister_ldisc(N_GIGASET_M101)) != 0)
+		err("error %d unregistering line discipline", rc);
+
+	platform_driver_unregister(&device_driver);
+}
+
+module_init(ser_gigaset_init);
+module_exit(ser_gigaset_exit);