linux/drivers/net/caif/caif_serial.c

456 lines
10 KiB
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 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);