/*
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* Copyright (C) ST-Ericsson AB 2010
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* Author: Sjur Brendeland
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* License terms: GNU General Public License (GPL) version 2
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*/
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#include <linux/hardirq.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/device.h>
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#include <linux/types.h>
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#include <linux/skbuff.h>
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#include <linux/netdevice.h>
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#include <linux/rtnetlink.h>
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#include <linux/tty.h>
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#include <linux/file.h>
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#include <linux/if_arp.h>
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#include <net/caif/caif_device.h>
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#include <net/caif/cfcnfg.h>
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#include <linux/err.h>
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#include <linux/debugfs.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Sjur Brendeland");
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MODULE_DESCRIPTION("CAIF serial device TTY line discipline");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_LDISC(N_CAIF);
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#define SEND_QUEUE_LOW 10
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#define SEND_QUEUE_HIGH 100
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#define CAIF_SENDING 1 /* Bit 1 = 0x02*/
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#define CAIF_FLOW_OFF_SENT 4 /* Bit 4 = 0x10 */
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#define MAX_WRITE_CHUNK 4096
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#define ON 1
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#define OFF 0
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#define CAIF_MAX_MTU 4096
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static DEFINE_SPINLOCK(ser_lock);
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static LIST_HEAD(ser_list);
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static LIST_HEAD(ser_release_list);
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static bool ser_loop;
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module_param(ser_loop, bool, 0444);
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MODULE_PARM_DESC(ser_loop, "Run in simulated loopback mode.");
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static bool ser_use_stx = true;
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module_param(ser_use_stx, bool, 0444);
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MODULE_PARM_DESC(ser_use_stx, "STX enabled or not.");
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static bool ser_use_fcs = true;
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module_param(ser_use_fcs, bool, 0444);
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MODULE_PARM_DESC(ser_use_fcs, "FCS enabled or not.");
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static int ser_write_chunk = MAX_WRITE_CHUNK;
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module_param(ser_write_chunk, int, 0444);
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MODULE_PARM_DESC(ser_write_chunk, "Maximum size of data written to UART.");
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static struct dentry *debugfsdir;
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static int caif_net_open(struct net_device *dev);
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static int caif_net_close(struct net_device *dev);
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struct ser_device {
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struct caif_dev_common common;
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struct list_head node;
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struct net_device *dev;
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struct sk_buff_head head;
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struct tty_struct *tty;
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bool tx_started;
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unsigned long state;
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#ifdef CONFIG_DEBUG_FS
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struct dentry *debugfs_tty_dir;
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struct debugfs_blob_wrapper tx_blob;
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struct debugfs_blob_wrapper rx_blob;
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u8 rx_data[128];
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u8 tx_data[128];
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u8 tty_status;
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#endif
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};
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static void caifdev_setup(struct net_device *dev);
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static void ldisc_tx_wakeup(struct tty_struct *tty);
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#ifdef CONFIG_DEBUG_FS
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static inline void update_tty_status(struct ser_device *ser)
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{
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ser->tty_status =
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ser->tty->stopped << 5 |
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ser->tty->flow_stopped << 3 |
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ser->tty->packet << 2 |
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ser->tty->port->low_latency << 1;
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}
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static inline void debugfs_init(struct ser_device *ser, struct tty_struct *tty)
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{
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ser->debugfs_tty_dir =
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debugfs_create_dir(tty->name, debugfsdir);
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if (!IS_ERR(ser->debugfs_tty_dir)) {
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debugfs_create_blob("last_tx_msg", 0400,
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ser->debugfs_tty_dir,
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&ser->tx_blob);
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debugfs_create_blob("last_rx_msg", 0400,
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ser->debugfs_tty_dir,
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&ser->rx_blob);
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debugfs_create_x32("ser_state", 0400,
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ser->debugfs_tty_dir,
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(u32 *)&ser->state);
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debugfs_create_x8("tty_status", 0400,
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ser->debugfs_tty_dir,
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&ser->tty_status);
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}
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ser->tx_blob.data = ser->tx_data;
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ser->tx_blob.size = 0;
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ser->rx_blob.data = ser->rx_data;
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ser->rx_blob.size = 0;
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}
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static inline void debugfs_deinit(struct ser_device *ser)
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{
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debugfs_remove_recursive(ser->debugfs_tty_dir);
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}
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static inline void debugfs_rx(struct ser_device *ser, const u8 *data, int size)
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{
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if (size > sizeof(ser->rx_data))
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size = sizeof(ser->rx_data);
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memcpy(ser->rx_data, data, size);
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ser->rx_blob.data = ser->rx_data;
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ser->rx_blob.size = size;
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}
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static inline void debugfs_tx(struct ser_device *ser, const u8 *data, int size)
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{
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if (size > sizeof(ser->tx_data))
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size = sizeof(ser->tx_data);
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memcpy(ser->tx_data, data, size);
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ser->tx_blob.data = ser->tx_data;
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ser->tx_blob.size = size;
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}
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#else
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static inline void debugfs_init(struct ser_device *ser, struct tty_struct *tty)
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{
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}
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static inline void debugfs_deinit(struct ser_device *ser)
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{
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}
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static inline void update_tty_status(struct ser_device *ser)
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{
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}
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static inline void debugfs_rx(struct ser_device *ser, const u8 *data, int size)
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{
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}
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static inline void debugfs_tx(struct ser_device *ser, const u8 *data, int size)
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{
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}
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#endif
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static void ldisc_receive(struct tty_struct *tty, const u8 *data,
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char *flags, int count)
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{
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struct sk_buff *skb = NULL;
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struct ser_device *ser;
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int ret;
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ser = tty->disc_data;
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/*
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* NOTE: flags may contain information about break or overrun.
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* This is not yet handled.
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*/
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/*
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* Workaround for garbage at start of transmission,
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* only enable if STX handling is not enabled.
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*/
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if (!ser->common.use_stx && !ser->tx_started) {
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dev_info(&ser->dev->dev,
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"Bytes received before initial transmission -"
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"bytes discarded.\n");
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return;
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}
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BUG_ON(ser->dev == NULL);
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/* Get a suitable caif packet and copy in data. */
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skb = netdev_alloc_skb(ser->dev, count+1);
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if (skb == NULL)
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return;
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skb_put_data(skb, data, count);
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skb->protocol = htons(ETH_P_CAIF);
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skb_reset_mac_header(skb);
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debugfs_rx(ser, data, count);
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/* Push received packet up the stack. */
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ret = netif_rx_ni(skb);
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if (!ret) {
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ser->dev->stats.rx_packets++;
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ser->dev->stats.rx_bytes += count;
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} else
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++ser->dev->stats.rx_dropped;
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update_tty_status(ser);
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}
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static int handle_tx(struct ser_device *ser)
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{
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struct tty_struct *tty;
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struct sk_buff *skb;
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int tty_wr, len, room;
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tty = ser->tty;
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ser->tx_started = true;
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/* Enter critical section */
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if (test_and_set_bit(CAIF_SENDING, &ser->state))
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return 0;
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/* skb_peek is safe because handle_tx is called after skb_queue_tail */
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while ((skb = skb_peek(&ser->head)) != NULL) {
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/* Make sure you don't write too much */
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len = skb->len;
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room = tty_write_room(tty);
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if (!room)
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break;
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if (room > ser_write_chunk)
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room = ser_write_chunk;
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if (len > room)
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len = room;
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/* Write to tty or loopback */
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if (!ser_loop) {
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tty_wr = tty->ops->write(tty, skb->data, len);
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update_tty_status(ser);
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} else {
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tty_wr = len;
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ldisc_receive(tty, skb->data, NULL, len);
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}
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ser->dev->stats.tx_packets++;
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ser->dev->stats.tx_bytes += tty_wr;
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/* Error on TTY ?! */
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if (tty_wr < 0)
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goto error;
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/* Reduce buffer written, and discard if empty */
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skb_pull(skb, tty_wr);
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if (skb->len == 0) {
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struct sk_buff *tmp = skb_dequeue(&ser->head);
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WARN_ON(tmp != skb);
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if (in_interrupt())
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dev_kfree_skb_irq(skb);
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else
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kfree_skb(skb);
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}
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}
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/* Send flow off if queue is empty */
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if (ser->head.qlen <= SEND_QUEUE_LOW &&
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test_and_clear_bit(CAIF_FLOW_OFF_SENT, &ser->state) &&
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ser->common.flowctrl != NULL)
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ser->common.flowctrl(ser->dev, ON);
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clear_bit(CAIF_SENDING, &ser->state);
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return 0;
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error:
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clear_bit(CAIF_SENDING, &ser->state);
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return tty_wr;
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}
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static int caif_xmit(struct sk_buff *skb, struct net_device *dev)
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{
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struct ser_device *ser;
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ser = netdev_priv(dev);
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/* Send flow off once, on high water mark */
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if (ser->head.qlen > SEND_QUEUE_HIGH &&
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!test_and_set_bit(CAIF_FLOW_OFF_SENT, &ser->state) &&
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ser->common.flowctrl != NULL)
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ser->common.flowctrl(ser->dev, OFF);
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skb_queue_tail(&ser->head, skb);
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return handle_tx(ser);
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}
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static void ldisc_tx_wakeup(struct tty_struct *tty)
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{
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struct ser_device *ser;
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ser = tty->disc_data;
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BUG_ON(ser == NULL);
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WARN_ON(ser->tty != tty);
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handle_tx(ser);
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}
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static void ser_release(struct work_struct *work)
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{
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struct list_head list;
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struct ser_device *ser, *tmp;
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spin_lock(&ser_lock);
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list_replace_init(&ser_release_list, &list);
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spin_unlock(&ser_lock);
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if (!list_empty(&list)) {
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rtnl_lock();
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list_for_each_entry_safe(ser, tmp, &list, node) {
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dev_close(ser->dev);
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unregister_netdevice(ser->dev);
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debugfs_deinit(ser);
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}
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rtnl_unlock();
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}
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}
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static DECLARE_WORK(ser_release_work, ser_release);
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static int ldisc_open(struct tty_struct *tty)
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{
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struct ser_device *ser;
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struct net_device *dev;
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char name[64];
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int result;
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/* No write no play */
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if (tty->ops->write == NULL)
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return -EOPNOTSUPP;
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if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_TTY_CONFIG))
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return -EPERM;
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/* release devices to avoid name collision */
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ser_release(NULL);
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result = snprintf(name, sizeof(name), "cf%s", tty->name);
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if (result >= IFNAMSIZ)
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return -EINVAL;
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dev = alloc_netdev(sizeof(*ser), name, NET_NAME_UNKNOWN,
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caifdev_setup);
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if (!dev)
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return -ENOMEM;
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ser = netdev_priv(dev);
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ser->tty = tty_kref_get(tty);
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ser->dev = dev;
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debugfs_init(ser, tty);
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tty->receive_room = N_TTY_BUF_SIZE;
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tty->disc_data = ser;
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set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
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rtnl_lock();
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result = register_netdevice(dev);
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if (result) {
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tty_kref_put(tty);
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rtnl_unlock();
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free_netdev(dev);
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return -ENODEV;
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}
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spin_lock(&ser_lock);
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list_add(&ser->node, &ser_list);
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spin_unlock(&ser_lock);
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rtnl_unlock();
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netif_stop_queue(dev);
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update_tty_status(ser);
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return 0;
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}
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static void ldisc_close(struct tty_struct *tty)
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{
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struct ser_device *ser = tty->disc_data;
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tty_kref_put(ser->tty);
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spin_lock(&ser_lock);
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list_move(&ser->node, &ser_release_list);
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spin_unlock(&ser_lock);
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schedule_work(&ser_release_work);
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}
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/* The line discipline structure. */
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static struct tty_ldisc_ops caif_ldisc = {
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.owner = THIS_MODULE,
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.magic = TTY_LDISC_MAGIC,
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.name = "n_caif",
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.open = ldisc_open,
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.close = ldisc_close,
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.receive_buf = ldisc_receive,
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.write_wakeup = ldisc_tx_wakeup
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};
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static int register_ldisc(void)
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{
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int result;
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result = tty_register_ldisc(N_CAIF, &caif_ldisc);
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if (result < 0) {
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pr_err("cannot register CAIF ldisc=%d err=%d\n", N_CAIF,
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result);
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return result;
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}
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return result;
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}
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static const struct net_device_ops netdev_ops = {
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.ndo_open = caif_net_open,
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.ndo_stop = caif_net_close,
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.ndo_start_xmit = caif_xmit
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};
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static void caifdev_setup(struct net_device *dev)
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{
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struct ser_device *serdev = netdev_priv(dev);
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dev->features = 0;
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dev->netdev_ops = &netdev_ops;
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dev->type = ARPHRD_CAIF;
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dev->flags = IFF_POINTOPOINT | IFF_NOARP;
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dev->mtu = CAIF_MAX_MTU;
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dev->priv_flags |= IFF_NO_QUEUE;
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dev->needs_free_netdev = true;
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skb_queue_head_init(&serdev->head);
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serdev->common.link_select = CAIF_LINK_LOW_LATENCY;
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serdev->common.use_frag = true;
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serdev->common.use_stx = ser_use_stx;
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serdev->common.use_fcs = ser_use_fcs;
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serdev->dev = dev;
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}
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static int caif_net_open(struct net_device *dev)
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{
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netif_wake_queue(dev);
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return 0;
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}
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static int caif_net_close(struct net_device *dev)
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{
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netif_stop_queue(dev);
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return 0;
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}
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static int __init caif_ser_init(void)
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{
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int ret;
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ret = register_ldisc();
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debugfsdir = debugfs_create_dir("caif_serial", NULL);
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return ret;
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}
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static void __exit caif_ser_exit(void)
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{
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spin_lock(&ser_lock);
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list_splice(&ser_list, &ser_release_list);
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spin_unlock(&ser_lock);
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ser_release(NULL);
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cancel_work_sync(&ser_release_work);
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tty_unregister_ldisc(N_CAIF);
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debugfs_remove_recursive(debugfsdir);
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}
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module_init(caif_ser_init);
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module_exit(caif_ser_exit);
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