[mirror_ubuntu-artful-kernel.git] / drivers / net / caif / caif_serial.c

/*
 * Copyright (C) ST-Ericsson AB 2010
 * Author:	Sjur Brendeland
 * 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");
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

static DEFINE_SPINLOCK(ser_lock);
static LIST_HEAD(ser_list);
static LIST_HEAD(ser_release_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;
#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;

	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;
	skb_put_data(skb, data, count);

	skb->protocol = htons(ETH_P_CAIF);
	skb_reset_mac_header(skb);
	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 void ser_release(struct work_struct *work)
{
	struct list_head list;
	struct ser_device *ser, *tmp;

	spin_lock(&ser_lock);
	list_replace_init(&ser_release_list, &list);
	spin_unlock(&ser_lock);

	if (!list_empty(&list)) {
		rtnl_lock();
		list_for_each_entry_safe(ser, tmp, &list, node) {
			dev_close(ser->dev);
			unregister_netdevice(ser->dev);
			debugfs_deinit(ser);
		}
		rtnl_unlock();
	}
}

static DECLARE_WORK(ser_release_work, ser_release);

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;

	/* release devices to avoid name collision */
	ser_release(NULL);

	result = snprintf(name, sizeof(name), "cf%s", tty->name);
	if (result >= IFNAMSIZ)
		return -EINVAL;
	dev = alloc_netdev(sizeof(*ser), name, NET_NAME_UNKNOWN,
			   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;
	}

	spin_lock(&ser_lock);
	list_add(&ser->node, &ser_list);
	spin_unlock(&ser_lock);
	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;

	tty_kref_put(ser->tty);

	spin_lock(&ser_lock);
	list_move(&ser->node, &ser_release_list);
	spin_unlock(&ser_lock);
	schedule_work(&ser_release_work);
}

/* 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->priv_flags |= IFF_NO_QUEUE;
	dev->needs_free_netdev = true;
	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)
{
	spin_lock(&ser_lock);
	list_splice(&ser_list, &ser_release_list);
	spin_unlock(&ser_lock);
	ser_release(NULL);
	cancel_work_sync(&ser_release_work);
	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	/*
9b27105b SB	2	* Copyright (C) ST-Ericsson AB 2010
26ee65e6	3	* Author: Sjur Brendeland
9b27105b SB	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");
26ee65e6	24	MODULE_AUTHOR("Sjur Brendeland");
9b27105b SB	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
56e0ef52	38	static DEFINE_SPINLOCK(ser_lock);
9b27105b	39	static LIST_HEAD(ser_list);
56e0ef52	40	static LIST_HEAD(ser_release_list);
9b27105b	41
eb939922	42	static bool ser_loop;
9b27105b SB	43	module_param(ser_loop, bool, S_IRUGO);
	44	MODULE_PARM_DESC(ser_loop, "Run in simulated loopback mode.");
	45
eb939922	46	static bool ser_use_stx = true;
9b27105b SB	47	module_param(ser_use_stx, bool, S_IRUGO);
	48	MODULE_PARM_DESC(ser_use_stx, "STX enabled or not.");
	49
eb939922	50	static bool ser_use_fcs = true;
9b27105b SB	51
	52	module_param(ser_use_fcs, bool, S_IRUGO);
	53	MODULE_PARM_DESC(ser_use_fcs, "FCS enabled or not.");
	54
	55	static int ser_write_chunk = MAX_WRITE_CHUNK;
	56	module_param(ser_write_chunk, int, S_IRUGO);
	57
	58	MODULE_PARM_DESC(ser_write_chunk, "Maximum size of data written to UART.");
	59
	60	static struct dentry *debugfsdir;
	61
	62	static int caif_net_open(struct net_device *dev);
	63	static int caif_net_close(struct net_device *dev);
	64
	65	struct ser_device {
	66	struct caif_dev_common common;
	67	struct list_head node;
	68	struct net_device *dev;
	69	struct sk_buff_head head;
	70	struct tty_struct *tty;
	71	bool tx_started;
	72	unsigned long state;
9b27105b SB	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;
c1f8fc57	174
9b27105b SB	175	ser = tty->disc_data;
	176
	177	/*
	178	* NOTE: flags may contain information about break or overrun.
	179	* This is not yet handled.
	180	*/
	181
	182
	183	/*
	184	* Workaround for garbage at start of transmission,
	185	* only enable if STX handling is not enabled.
	186	*/
	187	if (!ser->common.use_stx && !ser->tx_started) {
	188	dev_info(&ser->dev->dev,
	189	"Bytes received before initial transmission -"
	190	"bytes discarded.\n");
	191	return;
	192	}
	193
	194	BUG_ON(ser->dev == NULL);
	195
	196	/* Get a suitable caif packet and copy in data. */
	197	skb = netdev_alloc_skb(ser->dev, count+1);
d3f744e0 SB	198	if (skb == NULL)
d3f744e0 SB	199	return;
b952f4df	200	skb_put_data(skb, data, count);
9b27105b SB	201
	202	skb->protocol = htons(ETH_P_CAIF);
	203	skb_reset_mac_header(skb);
9b27105b SB	204	debugfs_rx(ser, data, count);
	205	/* Push received packet up the stack. */
	206	ret = netif_rx_ni(skb);
	207	if (!ret) {
	208	ser->dev->stats.rx_packets++;
	209	ser->dev->stats.rx_bytes += count;
	210	} else
	211	++ser->dev->stats.rx_dropped;
	212	update_tty_status(ser);
	213	}
	214
	215	static int handle_tx(struct ser_device *ser)
	216	{
	217	struct tty_struct *tty;
	218	struct sk_buff *skb;
	219	int tty_wr, len, room;
c1f8fc57	220
9b27105b SB	221	tty = ser->tty;
	222	ser->tx_started = true;
	223
	224	/* Enter critical section */
	225	if (test_and_set_bit(CAIF_SENDING, &ser->state))
	226	return 0;
	227
	228	/* skb_peek is safe because handle_tx is called after skb_queue_tail */
	229	while ((skb = skb_peek(&ser->head)) != NULL) {
	230
	231	/* Make sure you don't write too much */
	232	len = skb->len;
	233	room = tty_write_room(tty);
	234	if (!room)
	235	break;
	236	if (room > ser_write_chunk)
	237	room = ser_write_chunk;
	238	if (len > room)
	239	len = room;
	240
	241	/* Write to tty or loopback */
	242	if (!ser_loop) {
	243	tty_wr = tty->ops->write(tty, skb->data, len);
	244	update_tty_status(ser);
	245	} else {
	246	tty_wr = len;
	247	ldisc_receive(tty, skb->data, NULL, len);
	248	}
	249	ser->dev->stats.tx_packets++;
	250	ser->dev->stats.tx_bytes += tty_wr;
	251
	252	/* Error on TTY ?! */
	253	if (tty_wr < 0)
	254	goto error;
	255	/* Reduce buffer written, and discard if empty */
	256	skb_pull(skb, tty_wr);
	257	if (skb->len == 0) {
	258	struct sk_buff *tmp = skb_dequeue(&ser->head);
f84ea779	259	WARN_ON(tmp != skb);
9b27105b SB	260	if (in_interrupt())
	261	dev_kfree_skb_irq(skb);
	262	else
	263	kfree_skb(skb);
	264	}
	265	}
	266	/* Send flow off if queue is empty */
	267	if (ser->head.qlen <= SEND_QUEUE_LOW &&
	268	test_and_clear_bit(CAIF_FLOW_OFF_SENT, &ser->state) &&
	269	ser->common.flowctrl != NULL)
	270	ser->common.flowctrl(ser->dev, ON);
	271	clear_bit(CAIF_SENDING, &ser->state);
	272	return 0;
	273	error:
	274	clear_bit(CAIF_SENDING, &ser->state);
	275	return tty_wr;
	276	}
	277
	278	static int caif_xmit(struct sk_buff skb, struct net_device dev)
	279	{
	280	struct ser_device *ser;
c1f8fc57	281
9b27105b SB	282	BUG_ON(dev == NULL);
	283	ser = netdev_priv(dev);
	284
	285	/* Send flow off once, on high water mark */
	286	if (ser->head.qlen > SEND_QUEUE_HIGH &&
	287	!test_and_set_bit(CAIF_FLOW_OFF_SENT, &ser->state) &&
	288	ser->common.flowctrl != NULL)
	289
	290	ser->common.flowctrl(ser->dev, OFF);
	291
	292	skb_queue_tail(&ser->head, skb);
	293	return handle_tx(ser);
	294	}
	295
	296
	297	static void ldisc_tx_wakeup(struct tty_struct *tty)
	298	{
	299	struct ser_device *ser;
c1f8fc57	300
9b27105b SB	301	ser = tty->disc_data;
9b27105b SB	302	BUG_ON(ser == NULL);
f84ea779	303	WARN_ON(ser->tty != tty);
9b27105b SB	304	handle_tx(ser);
	305	}
	306
	307
56e0ef52 KK	308	static void ser_release(struct work_struct *work)
	309	{
	310	struct list_head list;
	311	struct ser_device ser, tmp;
	312
	313	spin_lock(&ser_lock);
	314	list_replace_init(&ser_release_list, &list);
	315	spin_unlock(&ser_lock);
	316
	317	if (!list_empty(&list)) {
	318	rtnl_lock();
	319	list_for_each_entry_safe(ser, tmp, &list, node) {
	320	dev_close(ser->dev);
	321	unregister_netdevice(ser->dev);
	322	debugfs_deinit(ser);
	323	}
	324	rtnl_unlock();
	325	}
	326	}
	327
	328	static DECLARE_WORK(ser_release_work, ser_release);
	329
9b27105b SB	330	static int ldisc_open(struct tty_struct *tty)
	331	{
	332	struct ser_device *ser;
	333	struct net_device *dev;
	334	char name[64];
	335	int result;
	336
c93f0940 AC	337	/* No write no play */
	338	if (tty->ops->write == NULL)
	339	return -EOPNOTSUPP;
d3f744e0 SB	340	if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_TTY_CONFIG))
d3f744e0 SB	341	return -EPERM;
c93f0940	342
56e0ef52 KK	343	/* release devices to avoid name collision */
	344	ser_release(NULL);
	345
cab6ce9e DC	346	result = snprintf(name, sizeof(name), "cf%s", tty->name);
	347	if (result >= IFNAMSIZ)
	348	return -EINVAL;
c835a677 TG	349	dev = alloc_netdev(sizeof(*ser), name, NET_NAME_UNKNOWN,
c835a677 TG	350	caifdev_setup);
c66b9b7d AC	351	if (!dev)
	352	return -ENOMEM;
	353
9b27105b	354	ser = netdev_priv(dev);
e31d5a05	355	ser->tty = tty_kref_get(tty);
9b27105b SB	356	ser->dev = dev;
	357	debugfs_init(ser, tty);
	358	tty->receive_room = N_TTY_BUF_SIZE;
	359	tty->disc_data = ser;
	360	set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
	361	rtnl_lock();
	362	result = register_netdevice(dev);
	363	if (result) {
	364	rtnl_unlock();
	365	free_netdev(dev);
	366	return -ENODEV;
	367	}
	368
56e0ef52	369	spin_lock(&ser_lock);
9b27105b	370	list_add(&ser->node, &ser_list);
56e0ef52	371	spin_unlock(&ser_lock);
9b27105b SB	372	rtnl_unlock();
	373	netif_stop_queue(dev);
	374	update_tty_status(ser);
	375	return 0;
	376	}
	377
	378	static void ldisc_close(struct tty_struct *tty)
	379	{
	380	struct ser_device *ser = tty->disc_data;
c1f8fc57	381
e31d5a05	382	tty_kref_put(ser->tty);
56e0ef52 KK	383
	384	spin_lock(&ser_lock);
	385	list_move(&ser->node, &ser_release_list);
	386	spin_unlock(&ser_lock);
	387	schedule_work(&ser_release_work);
9b27105b SB	388	}
	389
	390	/* The line discipline structure. */
	391	static struct tty_ldisc_ops caif_ldisc = {
	392	.owner = THIS_MODULE,
	393	.magic = TTY_LDISC_MAGIC,
	394	.name = "n_caif",
	395	.open = ldisc_open,
	396	.close = ldisc_close,
	397	.receive_buf = ldisc_receive,
	398	.write_wakeup = ldisc_tx_wakeup
	399	};
	400
	401	static int register_ldisc(void)
	402	{
	403	int result;
c1f8fc57	404
9b27105b SB	405	result = tty_register_ldisc(N_CAIF, &caif_ldisc);
	406	if (result < 0) {
	407	pr_err("cannot register CAIF ldisc=%d err=%d\n", N_CAIF,
	408	result);
	409	return result;
	410	}
	411	return result;
	412	}
	413	static const struct net_device_ops netdev_ops = {
	414	.ndo_open = caif_net_open,
	415	.ndo_stop = caif_net_close,
	416	.ndo_start_xmit = caif_xmit
	417	};
	418
	419	static void caifdev_setup(struct net_device *dev)
	420	{
	421	struct ser_device *serdev = netdev_priv(dev);
c1f8fc57	422
9b27105b SB	423	dev->features = 0;
	424	dev->netdev_ops = &netdev_ops;
	425	dev->type = ARPHRD_CAIF;
	426	dev->flags = IFF_POINTOPOINT \| IFF_NOARP;
	427	dev->mtu = CAIF_MAX_MTU;
4676a152	428	dev->priv_flags \|= IFF_NO_QUEUE;
cf124db5	429	dev->needs_free_netdev = true;
9b27105b SB	430	skb_queue_head_init(&serdev->head);
	431	serdev->common.link_select = CAIF_LINK_LOW_LATENCY;
	432	serdev->common.use_frag = true;
	433	serdev->common.use_stx = ser_use_stx;
	434	serdev->common.use_fcs = ser_use_fcs;
	435	serdev->dev = dev;
	436	}
	437
	438
	439	static int caif_net_open(struct net_device *dev)
	440	{
9b27105b SB	441	netif_wake_queue(dev);
	442	return 0;
	443	}
	444
	445	static int caif_net_close(struct net_device *dev)
	446	{
	447	netif_stop_queue(dev);
	448	return 0;
	449	}
	450
	451	static int __init caif_ser_init(void)
	452	{
	453	int ret;
c1f8fc57	454
9b27105b SB	455	ret = register_ldisc();
	456	debugfsdir = debugfs_create_dir("caif_serial", NULL);
	457	return ret;
	458	}
	459
	460	static void __exit caif_ser_exit(void)
	461	{
56e0ef52 KK	462	spin_lock(&ser_lock);
	463	list_splice(&ser_list, &ser_release_list);
	464	spin_unlock(&ser_lock);
	465	ser_release(NULL);
	466	cancel_work_sync(&ser_release_work);
9b27105b SB	467	tty_unregister_ldisc(N_CAIF);
	468	debugfs_remove_recursive(debugfsdir);
	469	}
	470
	471	module_init(caif_ser_init);
	472	module_exit(caif_ser_exit);