[deliverable/linux.git] / drivers / net / caif / caif_serial.c

/*
 * Copyright (C) ST-Ericsson AB 2010
 * Author:	Sjur Brendeland / sjur.brandeland@stericsson.com
 * License terms: GNU General Public License (GPL) version 2
 */

#include <linux/hardirq.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/types.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/rtnetlink.h>
#include <linux/tty.h>
#include <linux/file.h>
#include <linux/if_arp.h>
#include <net/caif/caif_device.h>
#include <net/caif/cfcnfg.h>
#include <linux/err.h>
#include <linux/debugfs.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Sjur Brendeland<sjur.brandeland@stericsson.com>");
MODULE_DESCRIPTION("CAIF serial device TTY line discipline");
MODULE_LICENSE("GPL");
MODULE_ALIAS_LDISC(N_CAIF);

#define SEND_QUEUE_LOW 10
#define SEND_QUEUE_HIGH 100
#define CAIF_SENDING	        1 /* Bit 1 = 0x02*/
#define CAIF_FLOW_OFF_SENT	4 /* Bit 4 = 0x10 */
#define MAX_WRITE_CHUNK	     4096
#define ON 1
#define OFF 0
#define CAIF_MAX_MTU 4096

/*This list is protected by the rtnl lock. */
static LIST_HEAD(ser_list);

static bool ser_loop;
module_param(ser_loop, bool, S_IRUGO);
MODULE_PARM_DESC(ser_loop, "Run in simulated loopback mode.");

static bool ser_use_stx = true;
module_param(ser_use_stx, bool, S_IRUGO);
MODULE_PARM_DESC(ser_use_stx, "STX enabled or not.");

static bool ser_use_fcs = true;

module_param(ser_use_fcs, bool, S_IRUGO);
MODULE_PARM_DESC(ser_use_fcs, "FCS enabled or not.");

static int ser_write_chunk = MAX_WRITE_CHUNK;
module_param(ser_write_chunk, int, S_IRUGO);

MODULE_PARM_DESC(ser_write_chunk, "Maximum size of data written to UART.");

static struct dentry *debugfsdir;

static int caif_net_open(struct net_device *dev);
static int caif_net_close(struct net_device *dev);

struct ser_device {
	struct caif_dev_common common;
	struct list_head node;
	struct net_device *dev;
	struct sk_buff_head head;
	struct tty_struct *tty;
	bool tx_started;
	unsigned long state;
	char *tty_name;
#ifdef CONFIG_DEBUG_FS
	struct dentry *debugfs_tty_dir;
	struct debugfs_blob_wrapper tx_blob;
	struct debugfs_blob_wrapper rx_blob;
	u8 rx_data[128];
	u8 tx_data[128];
	u8 tty_status;

#endif
};

static void caifdev_setup(struct net_device *dev);
static void ldisc_tx_wakeup(struct tty_struct *tty);
#ifdef CONFIG_DEBUG_FS
static inline void update_tty_status(struct ser_device *ser)
{
	ser->tty_status =
		ser->tty->stopped << 5 |
		ser->tty->flow_stopped << 3 |
		ser->tty->packet << 2 |
		ser->tty->port->low_latency << 1;
}
static inline void debugfs_init(struct ser_device *ser, struct tty_struct *tty)
{
	ser->debugfs_tty_dir =
			debugfs_create_dir(tty->name, debugfsdir);
	if (!IS_ERR(ser->debugfs_tty_dir)) {
		debugfs_create_blob("last_tx_msg", S_IRUSR,
				ser->debugfs_tty_dir,
				&ser->tx_blob);

		debugfs_create_blob("last_rx_msg", S_IRUSR,
				ser->debugfs_tty_dir,
				&ser->rx_blob);

		debugfs_create_x32("ser_state", S_IRUSR,
				ser->debugfs_tty_dir,
				(u32 *)&ser->state);

		debugfs_create_x8("tty_status", S_IRUSR,
				ser->debugfs_tty_dir,
				&ser->tty_status);

	}
	ser->tx_blob.data = ser->tx_data;
	ser->tx_blob.size = 0;
	ser->rx_blob.data = ser->rx_data;
	ser->rx_blob.size = 0;
}

static inline void debugfs_deinit(struct ser_device *ser)
{
	debugfs_remove_recursive(ser->debugfs_tty_dir);
}

static inline void debugfs_rx(struct ser_device *ser, const u8 *data, int size)
{
	if (size > sizeof(ser->rx_data))
		size = sizeof(ser->rx_data);
	memcpy(ser->rx_data, data, size);
	ser->rx_blob.data = ser->rx_data;
	ser->rx_blob.size = size;
}

static inline void debugfs_tx(struct ser_device *ser, const u8 *data, int size)
{
	if (size > sizeof(ser->tx_data))
		size = sizeof(ser->tx_data);
	memcpy(ser->tx_data, data, size);
	ser->tx_blob.data = ser->tx_data;
	ser->tx_blob.size = size;
}
#else
static inline void debugfs_init(struct ser_device *ser, struct tty_struct *tty)
{
}

static inline void debugfs_deinit(struct ser_device *ser)
{
}

static inline void update_tty_status(struct ser_device *ser)
{
}

static inline void debugfs_rx(struct ser_device *ser, const u8 *data, int size)
{
}

static inline void debugfs_tx(struct ser_device *ser, const u8 *data, int size)
{
}

#endif

static void ldisc_receive(struct tty_struct *tty, const u8 *data,
			char *flags, int count)
{
	struct sk_buff *skb = NULL;
	struct ser_device *ser;
	int ret;
	u8 *p;

	ser = tty->disc_data;

	/*
	 * NOTE: flags may contain information about break or overrun.
	 * This is not yet handled.
	 */


	/*
	 * Workaround for garbage at start of transmission,
	 * only enable if STX handling is not enabled.
	 */
	if (!ser->common.use_stx && !ser->tx_started) {
		dev_info(&ser->dev->dev,
			"Bytes received before initial transmission -"
			"bytes discarded.\n");
		return;
	}

	BUG_ON(ser->dev == NULL);

	/* Get a suitable caif packet and copy in data. */
	skb = netdev_alloc_skb(ser->dev, count+1);
	if (skb == NULL)
		return;
	p = skb_put(skb, count);
	memcpy(p, data, count);

	skb->protocol = htons(ETH_P_CAIF);
	skb_reset_mac_header(skb);
	skb->dev = ser->dev;
	debugfs_rx(ser, data, count);
	/* Push received packet up the stack. */
	ret = netif_rx_ni(skb);
	if (!ret) {
		ser->dev->stats.rx_packets++;
		ser->dev->stats.rx_bytes += count;
	} else
		++ser->dev->stats.rx_dropped;
	update_tty_status(ser);
}

static int handle_tx(struct ser_device *ser)
{
	struct tty_struct *tty;
	struct sk_buff *skb;
	int tty_wr, len, room;

	tty = ser->tty;
	ser->tx_started = true;

	/* Enter critical section */
	if (test_and_set_bit(CAIF_SENDING, &ser->state))
		return 0;

	/* skb_peek is safe because handle_tx is called after skb_queue_tail */
	while ((skb = skb_peek(&ser->head)) != NULL) {

		/* Make sure you don't write too much */
		len = skb->len;
		room = tty_write_room(tty);
		if (!room)
			break;
		if (room > ser_write_chunk)
			room = ser_write_chunk;
		if (len > room)
			len = room;

		/* Write to tty or loopback */
		if (!ser_loop) {
			tty_wr = tty->ops->write(tty, skb->data, len);
			update_tty_status(ser);
		} else {
			tty_wr = len;
			ldisc_receive(tty, skb->data, NULL, len);
		}
		ser->dev->stats.tx_packets++;
		ser->dev->stats.tx_bytes += tty_wr;

		/* Error on TTY ?! */
		if (tty_wr < 0)
			goto error;
		/* Reduce buffer written, and discard if empty */
		skb_pull(skb, tty_wr);
		if (skb->len == 0) {
			struct sk_buff *tmp = skb_dequeue(&ser->head);
			WARN_ON(tmp != skb);
			if (in_interrupt())
				dev_kfree_skb_irq(skb);
			else
				kfree_skb(skb);
		}
	}
	/* Send flow off if queue is empty */
	if (ser->head.qlen <= SEND_QUEUE_LOW &&
		test_and_clear_bit(CAIF_FLOW_OFF_SENT, &ser->state) &&
		ser->common.flowctrl != NULL)
				ser->common.flowctrl(ser->dev, ON);
	clear_bit(CAIF_SENDING, &ser->state);
	return 0;
error:
	clear_bit(CAIF_SENDING, &ser->state);
	return tty_wr;
}

static int caif_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct ser_device *ser;

	BUG_ON(dev == NULL);
	ser = netdev_priv(dev);

	/* Send flow off once, on high water mark */
	if (ser->head.qlen > SEND_QUEUE_HIGH &&
		!test_and_set_bit(CAIF_FLOW_OFF_SENT, &ser->state) &&
		ser->common.flowctrl != NULL)

		ser->common.flowctrl(ser->dev, OFF);

	skb_queue_tail(&ser->head, skb);
	return handle_tx(ser);
}


static void ldisc_tx_wakeup(struct tty_struct *tty)
{
	struct ser_device *ser;

	ser = tty->disc_data;
	BUG_ON(ser == NULL);
	WARN_ON(ser->tty != tty);
	handle_tx(ser);
}


static int ldisc_open(struct tty_struct *tty)
{
	struct ser_device *ser;
	struct net_device *dev;
	char name[64];
	int result;

	/* No write no play */
	if (tty->ops->write == NULL)
		return -EOPNOTSUPP;
	if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_TTY_CONFIG))
		return -EPERM;

	sprintf(name, "cf%s", tty->name);
	dev = alloc_netdev(sizeof(*ser), name, caifdev_setup);
	if (!dev)
		return -ENOMEM;

	ser = netdev_priv(dev);
	ser->tty = tty_kref_get(tty);
	ser->dev = dev;
	debugfs_init(ser, tty);
	tty->receive_room = N_TTY_BUF_SIZE;
	tty->disc_data = ser;
	set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
	rtnl_lock();
	result = register_netdevice(dev);
	if (result) {
		rtnl_unlock();
		free_netdev(dev);
		return -ENODEV;
	}

	list_add(&ser->node, &ser_list);
	rtnl_unlock();
	netif_stop_queue(dev);
	update_tty_status(ser);
	return 0;
}

static void ldisc_close(struct tty_struct *tty)
{
	struct ser_device *ser = tty->disc_data;
	/* Remove may be called inside or outside of rtnl_lock */
	int islocked = rtnl_is_locked();

	if (!islocked)
		rtnl_lock();
	/* device is freed automagically by net-sysfs */
	dev_close(ser->dev);
	unregister_netdevice(ser->dev);
	list_del(&ser->node);
	debugfs_deinit(ser);
	tty_kref_put(ser->tty);
	if (!islocked)
		rtnl_unlock();
}

/* The line discipline structure. */
static struct tty_ldisc_ops caif_ldisc = {
	.owner =	THIS_MODULE,
	.magic =	TTY_LDISC_MAGIC,
	.name =		"n_caif",
	.open =		ldisc_open,
	.close =	ldisc_close,
	.receive_buf =	ldisc_receive,
	.write_wakeup =	ldisc_tx_wakeup
};

static int register_ldisc(void)
{
	int result;

	result = tty_register_ldisc(N_CAIF, &caif_ldisc);
	if (result < 0) {
		pr_err("cannot register CAIF ldisc=%d err=%d\n", N_CAIF,
			result);
		return result;
	}
	return result;
}
static const struct net_device_ops netdev_ops = {
	.ndo_open = caif_net_open,
	.ndo_stop = caif_net_close,
	.ndo_start_xmit = caif_xmit
};

static void caifdev_setup(struct net_device *dev)
{
	struct ser_device *serdev = netdev_priv(dev);

	dev->features = 0;
	dev->netdev_ops = &netdev_ops;
	dev->type = ARPHRD_CAIF;
	dev->flags = IFF_POINTOPOINT | IFF_NOARP;
	dev->mtu = CAIF_MAX_MTU;
	dev->tx_queue_len = 0;
	dev->destructor = free_netdev;
	skb_queue_head_init(&serdev->head);
	serdev->common.link_select = CAIF_LINK_LOW_LATENCY;
	serdev->common.use_frag = true;
	serdev->common.use_stx = ser_use_stx;
	serdev->common.use_fcs = ser_use_fcs;
	serdev->dev = dev;
}


static int caif_net_open(struct net_device *dev)
{
	netif_wake_queue(dev);
	return 0;
}

static int caif_net_close(struct net_device *dev)
{
	netif_stop_queue(dev);
	return 0;
}

static int __init caif_ser_init(void)
{
	int ret;

	ret = register_ldisc();
	debugfsdir = debugfs_create_dir("caif_serial", NULL);
	return ret;
}

static void __exit caif_ser_exit(void)
{
	struct ser_device *ser = NULL;
	struct list_head *node;
	struct list_head *_tmp;

	list_for_each_safe(node, _tmp, &ser_list) {
		ser = list_entry(node, struct ser_device, node);
		dev_close(ser->dev);
		unregister_netdevice(ser->dev);
		list_del(node);
	}
	tty_unregister_ldisc(N_CAIF);
	debugfs_remove_recursive(debugfsdir);
}

module_init(caif_ser_init);
module_exit(caif_ser_exit);
Commit	Line	Data
9b27105b SB	1	/*
	2	* Copyright (C) ST-Ericsson AB 2010
	3	* Author: Sjur Brendeland / sjur.brandeland@stericsson.com
	4	* License terms: GNU General Public License (GPL) version 2
	5	*/
	6
a6b7a407	7	#include <linux/hardirq.h>
9b27105b	8	#include <linux/init.h>
9b27105b SB	9	#include <linux/module.h>
	10	#include <linux/device.h>
	11	#include <linux/types.h>
	12	#include <linux/skbuff.h>
	13	#include <linux/netdevice.h>
	14	#include <linux/rtnetlink.h>
	15	#include <linux/tty.h>
	16	#include <linux/file.h>
	17	#include <linux/if_arp.h>
	18	#include <net/caif/caif_device.h>
	19	#include <net/caif/cfcnfg.h>
	20	#include <linux/err.h>
	21	#include <linux/debugfs.h>
	22
	23	MODULE_LICENSE("GPL");
	24	MODULE_AUTHOR("Sjur Brendeland<sjur.brandeland@stericsson.com>");
	25	MODULE_DESCRIPTION("CAIF serial device TTY line discipline");
	26	MODULE_LICENSE("GPL");
	27	MODULE_ALIAS_LDISC(N_CAIF);
	28
	29	#define SEND_QUEUE_LOW 10
	30	#define SEND_QUEUE_HIGH 100
	31	#define CAIF_SENDING 1 /* Bit 1 = 0x02*/
	32	#define CAIF_FLOW_OFF_SENT 4 /* Bit 4 = 0x10 */
	33	#define MAX_WRITE_CHUNK 4096
	34	#define ON 1
	35	#define OFF 0
	36	#define CAIF_MAX_MTU 4096
	37
	38	/This list is protected by the rtnl lock. /
	39	static LIST_HEAD(ser_list);
	40
eb939922	41	static bool ser_loop;
9b27105b SB	42	module_param(ser_loop, bool, S_IRUGO);
	43	MODULE_PARM_DESC(ser_loop, "Run in simulated loopback mode.");
	44
eb939922	45	static bool ser_use_stx = true;
9b27105b SB	46	module_param(ser_use_stx, bool, S_IRUGO);
	47	MODULE_PARM_DESC(ser_use_stx, "STX enabled or not.");
	48
eb939922	49	static bool ser_use_fcs = true;
9b27105b SB	50
	51	module_param(ser_use_fcs, bool, S_IRUGO);
	52	MODULE_PARM_DESC(ser_use_fcs, "FCS enabled or not.");
	53
	54	static int ser_write_chunk = MAX_WRITE_CHUNK;
	55	module_param(ser_write_chunk, int, S_IRUGO);
	56
	57	MODULE_PARM_DESC(ser_write_chunk, "Maximum size of data written to UART.");
	58
	59	static struct dentry *debugfsdir;
	60
	61	static int caif_net_open(struct net_device *dev);
	62	static int caif_net_close(struct net_device *dev);
	63
	64	struct ser_device {
	65	struct caif_dev_common common;
	66	struct list_head node;
	67	struct net_device *dev;
	68	struct sk_buff_head head;
	69	struct tty_struct *tty;
	70	bool tx_started;
	71	unsigned long state;
	72	char *tty_name;
	73	#ifdef CONFIG_DEBUG_FS
	74	struct dentry *debugfs_tty_dir;
	75	struct debugfs_blob_wrapper tx_blob;
	76	struct debugfs_blob_wrapper rx_blob;
	77	u8 rx_data[128];
	78	u8 tx_data[128];
	79	u8 tty_status;
	80
	81	#endif
	82	};
	83
	84	static void caifdev_setup(struct net_device *dev);
	85	static void ldisc_tx_wakeup(struct tty_struct *tty);
	86	#ifdef CONFIG_DEBUG_FS
	87	static inline void update_tty_status(struct ser_device *ser)
	88	{
	89	ser->tty_status =
	90	ser->tty->stopped << 5 \|
9b27105b SB	91	ser->tty->flow_stopped << 3 \|
9b27105b SB	92	ser->tty->packet << 2 \|
0d3b88d1	93	ser->tty->port->low_latency << 1;
9b27105b SB	94	}
	95	static inline void debugfs_init(struct ser_device ser, struct tty_struct tty)
	96	{
	97	ser->debugfs_tty_dir =
	98	debugfs_create_dir(tty->name, debugfsdir);
	99	if (!IS_ERR(ser->debugfs_tty_dir)) {
	100	debugfs_create_blob("last_tx_msg", S_IRUSR,
	101	ser->debugfs_tty_dir,
	102	&ser->tx_blob);
	103
	104	debugfs_create_blob("last_rx_msg", S_IRUSR,
	105	ser->debugfs_tty_dir,
	106	&ser->rx_blob);
	107
	108	debugfs_create_x32("ser_state", S_IRUSR,
	109	ser->debugfs_tty_dir,
	110	(u32 *)&ser->state);
	111
	112	debugfs_create_x8("tty_status", S_IRUSR,
	113	ser->debugfs_tty_dir,
	114	&ser->tty_status);
	115
	116	}
	117	ser->tx_blob.data = ser->tx_data;
	118	ser->tx_blob.size = 0;
	119	ser->rx_blob.data = ser->rx_data;
	120	ser->rx_blob.size = 0;
	121	}
	122
	123	static inline void debugfs_deinit(struct ser_device *ser)
	124	{
	125	debugfs_remove_recursive(ser->debugfs_tty_dir);
	126	}
	127
	128	static inline void debugfs_rx(struct ser_device ser, const u8 data, int size)
	129	{
	130	if (size > sizeof(ser->rx_data))
	131	size = sizeof(ser->rx_data);
	132	memcpy(ser->rx_data, data, size);
	133	ser->rx_blob.data = ser->rx_data;
	134	ser->rx_blob.size = size;
	135	}
	136
	137	static inline void debugfs_tx(struct ser_device ser, const u8 data, int size)
	138	{
	139	if (size > sizeof(ser->tx_data))
	140	size = sizeof(ser->tx_data);
	141	memcpy(ser->tx_data, data, size);
	142	ser->tx_blob.data = ser->tx_data;
	143	ser->tx_blob.size = size;
	144	}
	145	#else
	146	static inline void debugfs_init(struct ser_device ser, struct tty_struct tty)
	147	{
	148	}
	149
	150	static inline void debugfs_deinit(struct ser_device *ser)
	151	{
	152	}
	153
	154	static inline void update_tty_status(struct ser_device *ser)
	155	{
	156	}
	157
158	static inline void debugfs_rx(struct ser_device ser, const u8 data, int size)
159	{
160	}
161
162	static inline void debugfs_tx(struct ser_device ser, const u8 data, int size)
163	{
164	}
165
166	#endif
167
55db4c64 LT	168	static void ldisc_receive(struct tty_struct tty, const u8 data,
55db4c64 LT	169	char *flags, int count)
9b27105b SB	170	{
	171	struct sk_buff *skb = NULL;
	172	struct ser_device *ser;
	173	int ret;
	174	u8 *p;
c1f8fc57	175
9b27105b SB	176	ser = tty->disc_data;
	177
	178	/*
	179	* NOTE: flags may contain information about break or overrun.
	180	* This is not yet handled.
	181	*/
	182
	183
	184	/*
	185	* Workaround for garbage at start of transmission,
	186	* only enable if STX handling is not enabled.
	187	*/
	188	if (!ser->common.use_stx && !ser->tx_started) {
	189	dev_info(&ser->dev->dev,
	190	"Bytes received before initial transmission -"
	191	"bytes discarded.\n");
	192	return;
	193	}
	194
	195	BUG_ON(ser->dev == NULL);
	196
	197	/* Get a suitable caif packet and copy in data. */
	198	skb = netdev_alloc_skb(ser->dev, count+1);
d3f744e0 SB	199	if (skb == NULL)
d3f744e0 SB	200	return;
9b27105b SB	201	p = skb_put(skb, count);
	202	memcpy(p, data, count);
	203
	204	skb->protocol = htons(ETH_P_CAIF);
	205	skb_reset_mac_header(skb);
	206	skb->dev = ser->dev;
	207	debugfs_rx(ser, data, count);
	208	/* Push received packet up the stack. */
	209	ret = netif_rx_ni(skb);
	210	if (!ret) {
	211	ser->dev->stats.rx_packets++;
	212	ser->dev->stats.rx_bytes += count;
	213	} else
	214	++ser->dev->stats.rx_dropped;
	215	update_tty_status(ser);
	216	}
	217
	218	static int handle_tx(struct ser_device *ser)
	219	{
	220	struct tty_struct *tty;
	221	struct sk_buff *skb;
	222	int tty_wr, len, room;
c1f8fc57	223
9b27105b SB	224	tty = ser->tty;
	225	ser->tx_started = true;
	226
	227	/* Enter critical section */
	228	if (test_and_set_bit(CAIF_SENDING, &ser->state))
	229	return 0;
	230
	231	/* skb_peek is safe because handle_tx is called after skb_queue_tail */
	232	while ((skb = skb_peek(&ser->head)) != NULL) {
	233
	234	/* Make sure you don't write too much */
	235	len = skb->len;
	236	room = tty_write_room(tty);
	237	if (!room)
	238	break;
	239	if (room > ser_write_chunk)
	240	room = ser_write_chunk;
	241	if (len > room)
	242	len = room;
	243
	244	/* Write to tty or loopback */
	245	if (!ser_loop) {
	246	tty_wr = tty->ops->write(tty, skb->data, len);
	247	update_tty_status(ser);
	248	} else {
	249	tty_wr = len;
	250	ldisc_receive(tty, skb->data, NULL, len);
	251	}
	252	ser->dev->stats.tx_packets++;
	253	ser->dev->stats.tx_bytes += tty_wr;
	254
	255	/* Error on TTY ?! */
	256	if (tty_wr < 0)
	257	goto error;
	258	/* Reduce buffer written, and discard if empty */
	259	skb_pull(skb, tty_wr);
	260	if (skb->len == 0) {
	261	struct sk_buff *tmp = skb_dequeue(&ser->head);
f84ea779	262	WARN_ON(tmp != skb);
9b27105b SB	263	if (in_interrupt())
	264	dev_kfree_skb_irq(skb);
	265	else
	266	kfree_skb(skb);
	267	}
	268	}
	269	/* Send flow off if queue is empty */
	270	if (ser->head.qlen <= SEND_QUEUE_LOW &&
	271	test_and_clear_bit(CAIF_FLOW_OFF_SENT, &ser->state) &&
	272	ser->common.flowctrl != NULL)
	273	ser->common.flowctrl(ser->dev, ON);
	274	clear_bit(CAIF_SENDING, &ser->state);
	275	return 0;
	276	error:
	277	clear_bit(CAIF_SENDING, &ser->state);
	278	return tty_wr;
	279	}
	280
	281	static int caif_xmit(struct sk_buff skb, struct net_device dev)
	282	{
	283	struct ser_device *ser;
c1f8fc57	284
9b27105b SB	285	BUG_ON(dev == NULL);
	286	ser = netdev_priv(dev);
	287
	288	/* Send flow off once, on high water mark */
	289	if (ser->head.qlen > SEND_QUEUE_HIGH &&
	290	!test_and_set_bit(CAIF_FLOW_OFF_SENT, &ser->state) &&
	291	ser->common.flowctrl != NULL)
	292
	293	ser->common.flowctrl(ser->dev, OFF);
	294
	295	skb_queue_tail(&ser->head, skb);
	296	return handle_tx(ser);
	297	}
	298
	299
	300	static void ldisc_tx_wakeup(struct tty_struct *tty)
	301	{
	302	struct ser_device *ser;
c1f8fc57	303
9b27105b SB	304	ser = tty->disc_data;
9b27105b SB	305	BUG_ON(ser == NULL);
f84ea779	306	WARN_ON(ser->tty != tty);
9b27105b SB	307	handle_tx(ser);
	308	}
	309
	310
	311	static int ldisc_open(struct tty_struct *tty)
	312	{
	313	struct ser_device *ser;
	314	struct net_device *dev;
	315	char name[64];
	316	int result;
	317
c93f0940 AC	318	/* No write no play */
	319	if (tty->ops->write == NULL)
	320	return -EOPNOTSUPP;
d3f744e0 SB	321	if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_TTY_CONFIG))
d3f744e0 SB	322	return -EPERM;
c93f0940	323
9b27105b SB	324	sprintf(name, "cf%s", tty->name);
9b27105b SB	325	dev = alloc_netdev(sizeof(*ser), name, caifdev_setup);
c66b9b7d AC	326	if (!dev)
	327	return -ENOMEM;
	328
9b27105b	329	ser = netdev_priv(dev);
e31d5a05	330	ser->tty = tty_kref_get(tty);
9b27105b SB	331	ser->dev = dev;
	332	debugfs_init(ser, tty);
	333	tty->receive_room = N_TTY_BUF_SIZE;
	334	tty->disc_data = ser;
	335	set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
	336	rtnl_lock();
	337	result = register_netdevice(dev);
	338	if (result) {
	339	rtnl_unlock();
	340	free_netdev(dev);
	341	return -ENODEV;
	342	}
	343
	344	list_add(&ser->node, &ser_list);
	345	rtnl_unlock();
	346	netif_stop_queue(dev);
	347	update_tty_status(ser);
	348	return 0;
	349	}
	350
	351	static void ldisc_close(struct tty_struct *tty)
	352	{
	353	struct ser_device *ser = tty->disc_data;
	354	/* Remove may be called inside or outside of rtnl_lock */
	355	int islocked = rtnl_is_locked();
c1f8fc57	356
9b27105b SB	357	if (!islocked)
	358	rtnl_lock();
	359	/* device is freed automagically by net-sysfs */
	360	dev_close(ser->dev);
	361	unregister_netdevice(ser->dev);
	362	list_del(&ser->node);
	363	debugfs_deinit(ser);
e31d5a05	364	tty_kref_put(ser->tty);
9b27105b SB	365	if (!islocked)
	366	rtnl_unlock();
	367	}
	368
	369	/* The line discipline structure. */
	370	static struct tty_ldisc_ops caif_ldisc = {
	371	.owner = THIS_MODULE,
	372	.magic = TTY_LDISC_MAGIC,
	373	.name = "n_caif",
	374	.open = ldisc_open,
	375	.close = ldisc_close,
	376	.receive_buf = ldisc_receive,
	377	.write_wakeup = ldisc_tx_wakeup
	378	};
	379
	380	static int register_ldisc(void)
	381	{
	382	int result;
c1f8fc57	383
9b27105b SB	384	result = tty_register_ldisc(N_CAIF, &caif_ldisc);
	385	if (result < 0) {
	386	pr_err("cannot register CAIF ldisc=%d err=%d\n", N_CAIF,
	387	result);
	388	return result;
	389	}
	390	return result;
	391	}
	392	static const struct net_device_ops netdev_ops = {
	393	.ndo_open = caif_net_open,
	394	.ndo_stop = caif_net_close,
	395	.ndo_start_xmit = caif_xmit
	396	};
	397
	398	static void caifdev_setup(struct net_device *dev)
	399	{
	400	struct ser_device *serdev = netdev_priv(dev);
c1f8fc57	401
9b27105b SB	402	dev->features = 0;
	403	dev->netdev_ops = &netdev_ops;
	404	dev->type = ARPHRD_CAIF;
	405	dev->flags = IFF_POINTOPOINT \| IFF_NOARP;
	406	dev->mtu = CAIF_MAX_MTU;
9b27105b SB	407	dev->tx_queue_len = 0;
	408	dev->destructor = free_netdev;
	409	skb_queue_head_init(&serdev->head);
	410	serdev->common.link_select = CAIF_LINK_LOW_LATENCY;
	411	serdev->common.use_frag = true;
	412	serdev->common.use_stx = ser_use_stx;
	413	serdev->common.use_fcs = ser_use_fcs;
	414	serdev->dev = dev;
	415	}
	416
	417
	418	static int caif_net_open(struct net_device *dev)
	419	{
9b27105b SB	420	netif_wake_queue(dev);
	421	return 0;
	422	}
	423
	424	static int caif_net_close(struct net_device *dev)
	425	{
	426	netif_stop_queue(dev);
	427	return 0;
	428	}
	429
	430	static int __init caif_ser_init(void)
	431	{
	432	int ret;
c1f8fc57	433
9b27105b SB	434	ret = register_ldisc();
	435	debugfsdir = debugfs_create_dir("caif_serial", NULL);
	436	return ret;
	437	}
	438
	439	static void __exit caif_ser_exit(void)
	440	{
	441	struct ser_device *ser = NULL;
	442	struct list_head *node;
	443	struct list_head *_tmp;
c1f8fc57	444
9b27105b SB	445	list_for_each_safe(node, _tmp, &ser_list) {
	446	ser = list_entry(node, struct ser_device, node);
	447	dev_close(ser->dev);
	448	unregister_netdevice(ser->dev);
	449	list_del(node);
	450	}
	451	tty_unregister_ldisc(N_CAIF);
	452	debugfs_remove_recursive(debugfsdir);
	453	}
	454
	455	module_init(caif_ser_init);
	456	module_exit(caif_ser_exit);