diff options
Diffstat (limited to 'drivers/net/caif/caif_serial.c')
| -rw-r--r-- | drivers/net/caif/caif_serial.c | 453 |
1 files changed, 453 insertions, 0 deletions
diff --git a/drivers/net/caif/caif_serial.c b/drivers/net/caif/caif_serial.c new file mode 100644 index 000000000..688075859 --- /dev/null +++ b/drivers/net/caif/caif_serial.c @@ -0,0 +1,453 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) ST-Ericsson AB 2010 + * Author: Sjur Brendeland + */ + +#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, 0444); +MODULE_PARM_DESC(ser_loop, "Run in simulated loopback mode."); + +static bool ser_use_stx = true; +module_param(ser_use_stx, bool, 0444); +MODULE_PARM_DESC(ser_use_stx, "STX enabled or not."); + +static bool ser_use_fcs = true; + +module_param(ser_use_fcs, bool, 0444); +MODULE_PARM_DESC(ser_use_fcs, "FCS enabled or not."); + +static int ser_write_chunk = MAX_WRITE_CHUNK; +module_param(ser_write_chunk, int, 0444); + +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->flow.stopped << 5 | + ser->tty->flow.tco_stopped << 3 | + ser->tty->ctrl.packet << 2; +} +static inline void debugfs_init(struct ser_device *ser, struct tty_struct *tty) +{ + ser->debugfs_tty_dir = debugfs_create_dir(tty->name, debugfsdir); + + debugfs_create_blob("last_tx_msg", 0400, ser->debugfs_tty_dir, + &ser->tx_blob); + + debugfs_create_blob("last_rx_msg", 0400, ser->debugfs_tty_dir, + &ser->rx_blob); + + debugfs_create_xul("ser_state", 0400, ser->debugfs_tty_dir, + &ser->state); + + debugfs_create_x8("tty_status", 0400, 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, + const 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(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); + dev_consume_skb_any(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 netdev_tx_t caif_xmit(struct sk_buff *skb, struct net_device *dev) +{ + struct ser_device *ser; + + 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) { + tty_kref_put(tty); + 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, + .num = N_CAIF, + .name = "n_caif", + .open = ldisc_open, + .close = ldisc_close, + .receive_buf = ldisc_receive, + .write_wakeup = ldisc_tx_wakeup +}; + +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 = tty_register_ldisc(&caif_ldisc); + if (ret < 0) + pr_err("cannot register CAIF ldisc=%d err=%d\n", N_CAIF, ret); + + 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(&caif_ldisc); + debugfs_remove_recursive(debugfsdir); +} + +module_init(caif_ser_init); +module_exit(caif_ser_exit); |