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461 lines
10 KiB
461 lines
10 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Copyright (C) ST-Ericsson AB 2010 |
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* Author: Sjur Brendeland |
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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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} |
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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 = debugfs_create_dir(tty->name, debugfsdir); |
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debugfs_create_blob("last_tx_msg", 0400, ser->debugfs_tty_dir, |
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&ser->tx_blob); |
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debugfs_create_blob("last_rx_msg", 0400, ser->debugfs_tty_dir, |
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&ser->rx_blob); |
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debugfs_create_xul("ser_state", 0400, ser->debugfs_tty_dir, |
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&ser->state); |
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debugfs_create_x8("tty_status", 0400, ser->debugfs_tty_dir, |
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&ser->tty_status); |
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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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dev_consume_skb_any(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 netdev_tx_t 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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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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