[linux-2.6-block.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;
	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);
	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, 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->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)
{
	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;
	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 \|
9b27105b SB	92	ser->tty->flow_stopped << 3 \|
9b27105b SB	93	ser->tty->packet << 2 \|
0d3b88d1	94	ser->tty->port->low_latency << 1;
9b27105b SB	95	}
	96	static inline void debugfs_init(struct ser_device ser, struct tty_struct tty)
	97	{
	98	ser->debugfs_tty_dir =
	99	debugfs_create_dir(tty->name, debugfsdir);
	100	if (!IS_ERR(ser->debugfs_tty_dir)) {
	101	debugfs_create_blob("last_tx_msg", S_IRUSR,
	102	ser->debugfs_tty_dir,
	103	&ser->tx_blob);
	104
	105	debugfs_create_blob("last_rx_msg", S_IRUSR,
	106	ser->debugfs_tty_dir,
	107	&ser->rx_blob);
	108
	109	debugfs_create_x32("ser_state", S_IRUSR,
	110	ser->debugfs_tty_dir,
	111	(u32 *)&ser->state);
	112
	113	debugfs_create_x8("tty_status", S_IRUSR,
	114	ser->debugfs_tty_dir,
	115	&ser->tty_status);
	116
	117	}
	118	ser->tx_blob.data = ser->tx_data;
	119	ser->tx_blob.size = 0;
	120	ser->rx_blob.data = ser->rx_data;
	121	ser->rx_blob.size = 0;
	122	}
	123
	124	static inline void debugfs_deinit(struct ser_device *ser)
	125	{
	126	debugfs_remove_recursive(ser->debugfs_tty_dir);
	127	}
	128
	129	static inline void debugfs_rx(struct ser_device ser, const u8 data, int size)
	130	{
	131	if (size > sizeof(ser->rx_data))
	132	size = sizeof(ser->rx_data);
	133	memcpy(ser->rx_data, data, size);
	134	ser->rx_blob.data = ser->rx_data;
	135	ser->rx_blob.size = size;
	136	}
	137
	138	static inline void debugfs_tx(struct ser_device ser, const u8 data, int size)
	139	{
	140	if (size > sizeof(ser->tx_data))
	141	size = sizeof(ser->tx_data);
	142	memcpy(ser->tx_data, data, size);
	143	ser->tx_blob.data = ser->tx_data;
	144	ser->tx_blob.size = size;
	145	}
	146	#else
	147	static inline void debugfs_init(struct ser_device ser, struct tty_struct tty)
	148	{
	149	}
	150
	151	static inline void debugfs_deinit(struct ser_device *ser)
	152	{
	153	}
	154
	155	static inline void update_tty_status(struct ser_device *ser)
	156	{
	157	}
	158
159	static inline void debugfs_rx(struct ser_device ser, const u8 data, int size)
160	{
161	}
162
163	static inline void debugfs_tx(struct ser_device ser, const u8 data, int size)
164	{
165	}
166
167	#endif
168
55db4c64 LT	169	static void ldisc_receive(struct tty_struct tty, const u8 data,
55db4c64 LT	170	char *flags, int count)
9b27105b SB	171	{
	172	struct sk_buff *skb = NULL;
	173	struct ser_device *ser;
	174	int ret;
	175	u8 *p;
c1f8fc57	176
9b27105b SB	177	ser = tty->disc_data;
	178
	179	/*
	180	* NOTE: flags may contain information about break or overrun.
	181	* This is not yet handled.
	182	*/
	183
	184
	185	/*
	186	* Workaround for garbage at start of transmission,
	187	* only enable if STX handling is not enabled.
	188	*/
	189	if (!ser->common.use_stx && !ser->tx_started) {
	190	dev_info(&ser->dev->dev,
	191	"Bytes received before initial transmission -"
	192	"bytes discarded.\n");
	193	return;
	194	}
	195
	196	BUG_ON(ser->dev == NULL);
	197
	198	/* Get a suitable caif packet and copy in data. */
	199	skb = netdev_alloc_skb(ser->dev, count+1);
d3f744e0 SB	200	if (skb == NULL)
d3f744e0 SB	201	return;
9b27105b SB	202	p = skb_put(skb, count);
	203	memcpy(p, data, count);
	204
	205	skb->protocol = htons(ETH_P_CAIF);
	206	skb_reset_mac_header(skb);
9b27105b SB	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
56e0ef52 KK	311	static void ser_release(struct work_struct *work)
	312	{
	313	struct list_head list;
	314	struct ser_device ser, tmp;
	315
	316	spin_lock(&ser_lock);
	317	list_replace_init(&ser_release_list, &list);
	318	spin_unlock(&ser_lock);
	319
	320	if (!list_empty(&list)) {
	321	rtnl_lock();
	322	list_for_each_entry_safe(ser, tmp, &list, node) {
	323	dev_close(ser->dev);
	324	unregister_netdevice(ser->dev);
	325	debugfs_deinit(ser);
	326	}
	327	rtnl_unlock();
	328	}
	329	}
	330
	331	static DECLARE_WORK(ser_release_work, ser_release);
	332
9b27105b SB	333	static int ldisc_open(struct tty_struct *tty)
	334	{
	335	struct ser_device *ser;
	336	struct net_device *dev;
	337	char name[64];
	338	int result;
	339
c93f0940 AC	340	/* No write no play */
	341	if (tty->ops->write == NULL)
	342	return -EOPNOTSUPP;
d3f744e0 SB	343	if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_TTY_CONFIG))
d3f744e0 SB	344	return -EPERM;
c93f0940	345
56e0ef52 KK	346	/* release devices to avoid name collision */
	347	ser_release(NULL);
	348
cab6ce9e DC	349	result = snprintf(name, sizeof(name), "cf%s", tty->name);
	350	if (result >= IFNAMSIZ)
	351	return -EINVAL;
9b27105b	352	dev = alloc_netdev(sizeof(*ser), name, caifdev_setup);
c66b9b7d AC	353	if (!dev)
	354	return -ENOMEM;
	355
9b27105b	356	ser = netdev_priv(dev);
e31d5a05	357	ser->tty = tty_kref_get(tty);
9b27105b SB	358	ser->dev = dev;
	359	debugfs_init(ser, tty);
	360	tty->receive_room = N_TTY_BUF_SIZE;
	361	tty->disc_data = ser;
	362	set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
	363	rtnl_lock();
	364	result = register_netdevice(dev);
	365	if (result) {
	366	rtnl_unlock();
	367	free_netdev(dev);
	368	return -ENODEV;
	369	}
	370
56e0ef52	371	spin_lock(&ser_lock);
9b27105b	372	list_add(&ser->node, &ser_list);
56e0ef52	373	spin_unlock(&ser_lock);
9b27105b SB	374	rtnl_unlock();
	375	netif_stop_queue(dev);
	376	update_tty_status(ser);
	377	return 0;
	378	}
	379
	380	static void ldisc_close(struct tty_struct *tty)
	381	{
	382	struct ser_device *ser = tty->disc_data;
c1f8fc57	383
e31d5a05	384	tty_kref_put(ser->tty);
56e0ef52 KK	385
	386	spin_lock(&ser_lock);
	387	list_move(&ser->node, &ser_release_list);
	388	spin_unlock(&ser_lock);
	389	schedule_work(&ser_release_work);
9b27105b SB	390	}
	391
	392	/* The line discipline structure. */
	393	static struct tty_ldisc_ops caif_ldisc = {
	394	.owner = THIS_MODULE,
	395	.magic = TTY_LDISC_MAGIC,
	396	.name = "n_caif",
	397	.open = ldisc_open,
	398	.close = ldisc_close,
	399	.receive_buf = ldisc_receive,
	400	.write_wakeup = ldisc_tx_wakeup
	401	};
	402
	403	static int register_ldisc(void)
	404	{
	405	int result;
c1f8fc57	406
9b27105b SB	407	result = tty_register_ldisc(N_CAIF, &caif_ldisc);
	408	if (result < 0) {
	409	pr_err("cannot register CAIF ldisc=%d err=%d\n", N_CAIF,
	410	result);
	411	return result;
	412	}
	413	return result;
	414	}
	415	static const struct net_device_ops netdev_ops = {
	416	.ndo_open = caif_net_open,
	417	.ndo_stop = caif_net_close,
	418	.ndo_start_xmit = caif_xmit
	419	};
	420
	421	static void caifdev_setup(struct net_device *dev)
	422	{
	423	struct ser_device *serdev = netdev_priv(dev);
c1f8fc57	424
9b27105b SB	425	dev->features = 0;
	426	dev->netdev_ops = &netdev_ops;
	427	dev->type = ARPHRD_CAIF;
	428	dev->flags = IFF_POINTOPOINT \| IFF_NOARP;
	429	dev->mtu = CAIF_MAX_MTU;
9b27105b SB	430	dev->tx_queue_len = 0;
	431	dev->destructor = free_netdev;
	432	skb_queue_head_init(&serdev->head);
	433	serdev->common.link_select = CAIF_LINK_LOW_LATENCY;
	434	serdev->common.use_frag = true;
	435	serdev->common.use_stx = ser_use_stx;
	436	serdev->common.use_fcs = ser_use_fcs;
	437	serdev->dev = dev;
	438	}
	439
	440
	441	static int caif_net_open(struct net_device *dev)
	442	{
9b27105b SB	443	netif_wake_queue(dev);
	444	return 0;
	445	}
	446
	447	static int caif_net_close(struct net_device *dev)
	448	{
	449	netif_stop_queue(dev);
	450	return 0;
	451	}
	452
	453	static int __init caif_ser_init(void)
	454	{
	455	int ret;
c1f8fc57	456
9b27105b SB	457	ret = register_ldisc();
	458	debugfsdir = debugfs_create_dir("caif_serial", NULL);
	459	return ret;
	460	}
	461
	462	static void __exit caif_ser_exit(void)
	463	{
56e0ef52 KK	464	spin_lock(&ser_lock);
	465	list_splice(&ser_list, &ser_release_list);
	466	spin_unlock(&ser_lock);
	467	ser_release(NULL);
	468	cancel_work_sync(&ser_release_work);
9b27105b SB	469	tty_unregister_ldisc(N_CAIF);
	470	debugfs_remove_recursive(debugfsdir);
	471	}
	472
	473	module_init(caif_ser_init);
	474	module_exit(caif_ser_exit);