[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/version.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 int ser_loop;
module_param(ser_loop, bool, S_IRUGO);
MODULE_PARM_DESC(ser_loop, "Run in simulated loopback mode.");

static int ser_use_stx = 1;
module_param(ser_use_stx, bool, S_IRUGO);
MODULE_PARM_DESC(ser_use_stx, "STX enabled or not.");

static int ser_use_fcs = 1;

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->hw_stopped << 4 |
		ser->tty->flow_stopped << 3 |
		ser->tty->packet << 2 |
		ser->tty->low_latency << 1 |
		ser->tty->warned;
}
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);
			BUG_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);
	BUG_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);
	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 SB	8	#include <linux/init.h>
	9	#include <linux/version.h>
	10	#include <linux/module.h>
	11	#include <linux/device.h>
	12	#include <linux/types.h>
	13	#include <linux/skbuff.h>
	14	#include <linux/netdevice.h>
	15	#include <linux/rtnetlink.h>
	16	#include <linux/tty.h>
	17	#include <linux/file.h>
	18	#include <linux/if_arp.h>
	19	#include <net/caif/caif_device.h>
	20	#include <net/caif/cfcnfg.h>
	21	#include <linux/err.h>
	22	#include <linux/debugfs.h>
	23
	24	MODULE_LICENSE("GPL");
	25	MODULE_AUTHOR("Sjur Brendeland<sjur.brandeland@stericsson.com>");
	26	MODULE_DESCRIPTION("CAIF serial device TTY line discipline");
	27	MODULE_LICENSE("GPL");
	28	MODULE_ALIAS_LDISC(N_CAIF);
	29
	30	#define SEND_QUEUE_LOW 10
	31	#define SEND_QUEUE_HIGH 100
	32	#define CAIF_SENDING 1 /* Bit 1 = 0x02*/
	33	#define CAIF_FLOW_OFF_SENT 4 /* Bit 4 = 0x10 */
	34	#define MAX_WRITE_CHUNK 4096
	35	#define ON 1
	36	#define OFF 0
	37	#define CAIF_MAX_MTU 4096
	38
	39	/This list is protected by the rtnl lock. /
	40	static LIST_HEAD(ser_list);
	41
	42	static int ser_loop;
	43	module_param(ser_loop, bool, S_IRUGO);
	44	MODULE_PARM_DESC(ser_loop, "Run in simulated loopback mode.");
	45
	46	static int ser_use_stx = 1;
	47	module_param(ser_use_stx, bool, S_IRUGO);
	48	MODULE_PARM_DESC(ser_use_stx, "STX enabled or not.");
	49
	50	static int ser_use_fcs = 1;
	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;
73	char *tty_name;
74	#ifdef CONFIG_DEBUG_FS
75	struct dentry *debugfs_tty_dir;
76	struct debugfs_blob_wrapper tx_blob;
77	struct debugfs_blob_wrapper rx_blob;
78	u8 rx_data[128];
79	u8 tx_data[128];
80	u8 tty_status;
81
82	#endif
83	};
84
85	static void caifdev_setup(struct net_device *dev);
86	static void ldisc_tx_wakeup(struct tty_struct *tty);
87	#ifdef CONFIG_DEBUG_FS
88	static inline void update_tty_status(struct ser_device *ser)
89	{
90	ser->tty_status =
91	ser->tty->stopped << 5 \|
92	ser->tty->hw_stopped << 4 \|
93	ser->tty->flow_stopped << 3 \|
94	ser->tty->packet << 2 \|
95	ser->tty->low_latency << 1 \|
96	ser->tty->warned;
97	}
98	static inline void debugfs_init(struct ser_device ser, struct tty_struct tty)
99	{
100	ser->debugfs_tty_dir =
101	debugfs_create_dir(tty->name, debugfsdir);
102	if (!IS_ERR(ser->debugfs_tty_dir)) {
103	debugfs_create_blob("last_tx_msg", S_IRUSR,
104	ser->debugfs_tty_dir,
105	&ser->tx_blob);
106
107	debugfs_create_blob("last_rx_msg", S_IRUSR,
108	ser->debugfs_tty_dir,
109	&ser->rx_blob);
110
111	debugfs_create_x32("ser_state", S_IRUSR,
112	ser->debugfs_tty_dir,
113	(u32 *)&ser->state);
114
115	debugfs_create_x8("tty_status", S_IRUSR,
116	ser->debugfs_tty_dir,
117	&ser->tty_status);
118
119	}
120	ser->tx_blob.data = ser->tx_data;
121	ser->tx_blob.size = 0;
122	ser->rx_blob.data = ser->rx_data;
123	ser->rx_blob.size = 0;
124	}
125
126	static inline void debugfs_deinit(struct ser_device *ser)
127	{
128	debugfs_remove_recursive(ser->debugfs_tty_dir);
129	}
130
131	static inline void debugfs_rx(struct ser_device ser, const u8 data, int size)
132	{
133	if (size > sizeof(ser->rx_data))
134	size = sizeof(ser->rx_data);
135	memcpy(ser->rx_data, data, size);
136	ser->rx_blob.data = ser->rx_data;
137	ser->rx_blob.size = size;
138	}
139
140	static inline void debugfs_tx(struct ser_device ser, const u8 data, int size)
141	{
142	if (size > sizeof(ser->tx_data))
143	size = sizeof(ser->tx_data);
144	memcpy(ser->tx_data, data, size);
145	ser->tx_blob.data = ser->tx_data;
146	ser->tx_blob.size = size;
147	}
148	#else
149	static inline void debugfs_init(struct ser_device ser, struct tty_struct tty)
150	{
151	}
152
153	static inline void debugfs_deinit(struct ser_device *ser)
154	{
155	}
156
157	static inline void update_tty_status(struct ser_device *ser)
158	{
159	}
160
161	static inline void debugfs_rx(struct ser_device ser, const u8 data, int size)
162	{
163	}
164
165	static inline void debugfs_tx(struct ser_device ser, const u8 data, int size)
166	{
167	}
168
169	#endif
170
55db4c64 LT	171	static void ldisc_receive(struct tty_struct tty, const u8 data,
55db4c64 LT	172	char *flags, int count)
9b27105b SB	173	{
	174	struct sk_buff *skb = NULL;
	175	struct ser_device *ser;
	176	int ret;
	177	u8 *p;
c1f8fc57	178
9b27105b SB	179	ser = tty->disc_data;
	180
	181	/*
	182	* NOTE: flags may contain information about break or overrun.
	183	* This is not yet handled.
	184	*/
	185
	186
	187	/*
	188	* Workaround for garbage at start of transmission,
	189	* only enable if STX handling is not enabled.
	190	*/
	191	if (!ser->common.use_stx && !ser->tx_started) {
	192	dev_info(&ser->dev->dev,
	193	"Bytes received before initial transmission -"
	194	"bytes discarded.\n");
	195	return;
	196	}
	197
	198	BUG_ON(ser->dev == NULL);
	199
	200	/* Get a suitable caif packet and copy in data. */
	201	skb = netdev_alloc_skb(ser->dev, count+1);
d3f744e0 SB	202	if (skb == NULL)
d3f744e0 SB	203	return;
9b27105b SB	204	p = skb_put(skb, count);
	205	memcpy(p, data, count);
	206
	207	skb->protocol = htons(ETH_P_CAIF);
	208	skb_reset_mac_header(skb);
	209	skb->dev = ser->dev;
	210	debugfs_rx(ser, data, count);
	211	/* Push received packet up the stack. */
	212	ret = netif_rx_ni(skb);
	213	if (!ret) {
	214	ser->dev->stats.rx_packets++;
	215	ser->dev->stats.rx_bytes += count;
	216	} else
	217	++ser->dev->stats.rx_dropped;
	218	update_tty_status(ser);
	219	}
	220
	221	static int handle_tx(struct ser_device *ser)
	222	{
	223	struct tty_struct *tty;
	224	struct sk_buff *skb;
	225	int tty_wr, len, room;
c1f8fc57	226
9b27105b SB	227	tty = ser->tty;
	228	ser->tx_started = true;
	229
	230	/* Enter critical section */
	231	if (test_and_set_bit(CAIF_SENDING, &ser->state))
	232	return 0;
	233
	234	/* skb_peek is safe because handle_tx is called after skb_queue_tail */
	235	while ((skb = skb_peek(&ser->head)) != NULL) {
	236
	237	/* Make sure you don't write too much */
	238	len = skb->len;
	239	room = tty_write_room(tty);
	240	if (!room)
	241	break;
	242	if (room > ser_write_chunk)
	243	room = ser_write_chunk;
	244	if (len > room)
	245	len = room;
	246
	247	/* Write to tty or loopback */
	248	if (!ser_loop) {
	249	tty_wr = tty->ops->write(tty, skb->data, len);
	250	update_tty_status(ser);
	251	} else {
	252	tty_wr = len;
	253	ldisc_receive(tty, skb->data, NULL, len);
	254	}
	255	ser->dev->stats.tx_packets++;
	256	ser->dev->stats.tx_bytes += tty_wr;
	257
	258	/* Error on TTY ?! */
	259	if (tty_wr < 0)
	260	goto error;
	261	/* Reduce buffer written, and discard if empty */
	262	skb_pull(skb, tty_wr);
	263	if (skb->len == 0) {
	264	struct sk_buff *tmp = skb_dequeue(&ser->head);
	265	BUG_ON(tmp != skb);
	266	if (in_interrupt())
	267	dev_kfree_skb_irq(skb);
	268	else
	269	kfree_skb(skb);
	270	}
	271	}
	272	/* Send flow off if queue is empty */
	273	if (ser->head.qlen <= SEND_QUEUE_LOW &&
	274	test_and_clear_bit(CAIF_FLOW_OFF_SENT, &ser->state) &&
	275	ser->common.flowctrl != NULL)
	276	ser->common.flowctrl(ser->dev, ON);
	277	clear_bit(CAIF_SENDING, &ser->state);
	278	return 0;
	279	error:
	280	clear_bit(CAIF_SENDING, &ser->state);
	281	return tty_wr;
	282	}
	283
	284	static int caif_xmit(struct sk_buff skb, struct net_device dev)
	285	{
	286	struct ser_device *ser;
c1f8fc57	287
9b27105b SB	288	BUG_ON(dev == NULL);
	289	ser = netdev_priv(dev);
	290
	291	/* Send flow off once, on high water mark */
	292	if (ser->head.qlen > SEND_QUEUE_HIGH &&
	293	!test_and_set_bit(CAIF_FLOW_OFF_SENT, &ser->state) &&
	294	ser->common.flowctrl != NULL)
	295
	296	ser->common.flowctrl(ser->dev, OFF);
	297
	298	skb_queue_tail(&ser->head, skb);
	299	return handle_tx(ser);
	300	}
	301
	302
	303	static void ldisc_tx_wakeup(struct tty_struct *tty)
	304	{
	305	struct ser_device *ser;
c1f8fc57	306
9b27105b SB	307	ser = tty->disc_data;
	308	BUG_ON(ser == NULL);
	309	BUG_ON(ser->tty != tty);
	310	handle_tx(ser);
	311	}
	312
	313
	314	static int ldisc_open(struct tty_struct *tty)
	315	{
	316	struct ser_device *ser;
	317	struct net_device *dev;
	318	char name[64];
	319	int result;
	320
c93f0940 AC	321	/* No write no play */
	322	if (tty->ops->write == NULL)
	323	return -EOPNOTSUPP;
d3f744e0 SB	324	if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_TTY_CONFIG))
d3f744e0 SB	325	return -EPERM;
c93f0940	326
9b27105b SB	327	sprintf(name, "cf%s", tty->name);
	328	dev = alloc_netdev(sizeof(*ser), name, caifdev_setup);
	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);