257 lines
9.2 KiB
C
257 lines
9.2 KiB
C
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_TTY_PORT_H
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#define _LINUX_TTY_PORT_H
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#include <linux/kfifo.h>
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#include <linux/kref.h>
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#include <linux/mutex.h>
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#include <linux/tty_buffer.h>
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#include <linux/wait.h>
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struct attribute_group;
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struct tty_driver;
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struct tty_port;
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struct tty_struct;
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/**
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* struct tty_port_operations -- operations on tty_port
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* @carrier_raised: return true if the carrier is raised on @port
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* @dtr_rts: raise the DTR line if @active is true, otherwise lower DTR
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* @shutdown: called when the last close completes or a hangup finishes IFF the
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* port was initialized. Do not use to free resources. Turn off the device
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* only. Called under the port mutex to serialize against @activate and
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* @shutdown.
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* @activate: called under the port mutex from tty_port_open(), serialized using
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* the port mutex. Supposed to turn on the device.
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*
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* FIXME: long term getting the tty argument *out* of this would be good
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* for consoles.
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*
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* @destruct: called on the final put of a port. Free resources, possibly incl.
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* the port itself.
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*/
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struct tty_port_operations {
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bool (*carrier_raised)(struct tty_port *port);
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void (*dtr_rts)(struct tty_port *port, bool active);
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void (*shutdown)(struct tty_port *port);
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int (*activate)(struct tty_port *port, struct tty_struct *tty);
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void (*destruct)(struct tty_port *port);
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};
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struct tty_port_client_operations {
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int (*receive_buf)(struct tty_port *port, const unsigned char *, const unsigned char *, size_t);
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void (*lookahead_buf)(struct tty_port *port, const unsigned char *cp,
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const unsigned char *fp, unsigned int count);
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void (*write_wakeup)(struct tty_port *port);
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};
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extern const struct tty_port_client_operations tty_port_default_client_ops;
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/**
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* struct tty_port -- port level information
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*
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* @buf: buffer for this port, locked internally
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* @tty: back pointer to &struct tty_struct, valid only if the tty is open. Use
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* tty_port_tty_get() to obtain it (and tty_kref_put() to release).
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* @itty: internal back pointer to &struct tty_struct. Avoid this. It should be
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* eliminated in the long term.
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* @ops: tty port operations (like activate, shutdown), see &struct
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* tty_port_operations
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* @client_ops: tty port client operations (like receive_buf, write_wakeup).
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* By default, tty_port_default_client_ops is used.
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* @lock: lock protecting @tty
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* @blocked_open: # of procs waiting for open in tty_port_block_til_ready()
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* @count: usage count
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* @open_wait: open waiters queue (waiting e.g. for a carrier)
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* @delta_msr_wait: modem status change queue (waiting for MSR changes)
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* @flags: user TTY flags (%ASYNC_)
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* @iflags: internal flags (%TTY_PORT_)
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* @console: when set, the port is a console
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* @mutex: locking, for open, shutdown and other port operations
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* @buf_mutex: @xmit_buf alloc lock
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* @xmit_buf: optional xmit buffer used by some drivers
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* @xmit_fifo: optional xmit buffer used by some drivers
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* @close_delay: delay in jiffies to wait when closing the port
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* @closing_wait: delay in jiffies for output to be sent before closing
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* @drain_delay: set to zero if no pure time based drain is needed else set to
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* size of fifo
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* @kref: references counter. Reaching zero calls @ops->destruct() if non-%NULL
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* or frees the port otherwise.
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* @client_data: pointer to private data, for @client_ops
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*
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* Each device keeps its own port level information. &struct tty_port was
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* introduced as a common structure for such information. As every TTY device
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* shall have a backing tty_port structure, every driver can use these members.
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*
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* The tty port has a different lifetime to the tty so must be kept apart.
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* In addition be careful as tty -> port mappings are valid for the life
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* of the tty object but in many cases port -> tty mappings are valid only
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* until a hangup so don't use the wrong path.
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*
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* Tty port shall be initialized by tty_port_init() and shut down either by
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* tty_port_destroy() (refcounting not used), or tty_port_put() (refcounting).
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*
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* There is a lot of helpers around &struct tty_port too. To name the most
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* significant ones: tty_port_open(), tty_port_close() (or
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* tty_port_close_start() and tty_port_close_end() separately if need be), and
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* tty_port_hangup(). These call @ops->activate() and @ops->shutdown() as
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* needed.
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*/
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struct tty_port {
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struct tty_bufhead buf;
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struct tty_struct *tty;
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struct tty_struct *itty;
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const struct tty_port_operations *ops;
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const struct tty_port_client_operations *client_ops;
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spinlock_t lock;
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int blocked_open;
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int count;
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wait_queue_head_t open_wait;
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wait_queue_head_t delta_msr_wait;
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unsigned long flags;
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unsigned long iflags;
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unsigned char console:1;
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struct mutex mutex;
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struct mutex buf_mutex;
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unsigned char *xmit_buf;
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DECLARE_KFIFO_PTR(xmit_fifo, unsigned char);
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unsigned int close_delay;
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unsigned int closing_wait;
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int drain_delay;
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struct kref kref;
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void *client_data;
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};
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/* tty_port::iflags bits -- use atomic bit ops */
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#define TTY_PORT_INITIALIZED 0 /* device is initialized */
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#define TTY_PORT_SUSPENDED 1 /* device is suspended */
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#define TTY_PORT_ACTIVE 2 /* device is open */
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/*
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* uart drivers: use the uart_port::status field and the UPSTAT_* defines
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* for s/w-based flow control steering and carrier detection status
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*/
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#define TTY_PORT_CTS_FLOW 3 /* h/w flow control enabled */
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#define TTY_PORT_CHECK_CD 4 /* carrier detect enabled */
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#define TTY_PORT_KOPENED 5 /* device exclusively opened by
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kernel */
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void tty_port_init(struct tty_port *port);
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void tty_port_link_device(struct tty_port *port, struct tty_driver *driver,
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unsigned index);
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struct device *tty_port_register_device(struct tty_port *port,
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struct tty_driver *driver, unsigned index,
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struct device *device);
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struct device *tty_port_register_device_attr(struct tty_port *port,
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struct tty_driver *driver, unsigned index,
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struct device *device, void *drvdata,
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const struct attribute_group **attr_grp);
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struct device *tty_port_register_device_serdev(struct tty_port *port,
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struct tty_driver *driver, unsigned index,
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struct device *device);
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struct device *tty_port_register_device_attr_serdev(struct tty_port *port,
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struct tty_driver *driver, unsigned index,
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struct device *device, void *drvdata,
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const struct attribute_group **attr_grp);
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void tty_port_unregister_device(struct tty_port *port,
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struct tty_driver *driver, unsigned index);
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int tty_port_alloc_xmit_buf(struct tty_port *port);
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void tty_port_free_xmit_buf(struct tty_port *port);
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void tty_port_destroy(struct tty_port *port);
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void tty_port_put(struct tty_port *port);
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static inline struct tty_port *tty_port_get(struct tty_port *port)
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{
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if (port && kref_get_unless_zero(&port->kref))
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return port;
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return NULL;
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}
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/* If the cts flow control is enabled, return true. */
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static inline bool tty_port_cts_enabled(const struct tty_port *port)
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{
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return test_bit(TTY_PORT_CTS_FLOW, &port->iflags);
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}
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static inline void tty_port_set_cts_flow(struct tty_port *port, bool val)
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{
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assign_bit(TTY_PORT_CTS_FLOW, &port->iflags, val);
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}
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static inline bool tty_port_active(const struct tty_port *port)
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{
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return test_bit(TTY_PORT_ACTIVE, &port->iflags);
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}
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static inline void tty_port_set_active(struct tty_port *port, bool val)
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{
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assign_bit(TTY_PORT_ACTIVE, &port->iflags, val);
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}
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static inline bool tty_port_check_carrier(const struct tty_port *port)
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{
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return test_bit(TTY_PORT_CHECK_CD, &port->iflags);
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}
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static inline void tty_port_set_check_carrier(struct tty_port *port, bool val)
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{
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assign_bit(TTY_PORT_CHECK_CD, &port->iflags, val);
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}
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static inline bool tty_port_suspended(const struct tty_port *port)
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{
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return test_bit(TTY_PORT_SUSPENDED, &port->iflags);
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}
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static inline void tty_port_set_suspended(struct tty_port *port, bool val)
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{
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assign_bit(TTY_PORT_SUSPENDED, &port->iflags, val);
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}
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static inline bool tty_port_initialized(const struct tty_port *port)
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{
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return test_bit(TTY_PORT_INITIALIZED, &port->iflags);
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}
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static inline void tty_port_set_initialized(struct tty_port *port, bool val)
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{
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assign_bit(TTY_PORT_INITIALIZED, &port->iflags, val);
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}
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static inline bool tty_port_kopened(const struct tty_port *port)
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{
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return test_bit(TTY_PORT_KOPENED, &port->iflags);
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}
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static inline void tty_port_set_kopened(struct tty_port *port, bool val)
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{
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assign_bit(TTY_PORT_KOPENED, &port->iflags, val);
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}
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struct tty_struct *tty_port_tty_get(struct tty_port *port);
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void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty);
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bool tty_port_carrier_raised(struct tty_port *port);
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void tty_port_raise_dtr_rts(struct tty_port *port);
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void tty_port_lower_dtr_rts(struct tty_port *port);
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void tty_port_hangup(struct tty_port *port);
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void tty_port_tty_hangup(struct tty_port *port, bool check_clocal);
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void tty_port_tty_wakeup(struct tty_port *port);
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int tty_port_block_til_ready(struct tty_port *port, struct tty_struct *tty,
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struct file *filp);
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int tty_port_close_start(struct tty_port *port, struct tty_struct *tty,
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struct file *filp);
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void tty_port_close_end(struct tty_port *port, struct tty_struct *tty);
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void tty_port_close(struct tty_port *port, struct tty_struct *tty,
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struct file *filp);
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int tty_port_install(struct tty_port *port, struct tty_driver *driver,
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struct tty_struct *tty);
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int tty_port_open(struct tty_port *port, struct tty_struct *tty,
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struct file *filp);
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static inline int tty_port_users(struct tty_port *port)
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{
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return port->count + port->blocked_open;
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}
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#endif
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