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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_TTY_PORT_H
#define _LINUX_TTY_PORT_H
#include <linux/kfifo.h>
#include <linux/kref.h>
#include <linux/mutex.h>
#include <linux/tty_buffer.h>
#include <linux/wait.h>
struct attribute_group;
struct tty_driver;
struct tty_port;
struct tty_struct;
/**
* struct tty_port_operations -- operations on tty_port
* @carrier_raised: return true if the carrier is raised on @port
* @dtr_rts: raise the DTR line if @active is true, otherwise lower DTR
* @shutdown: called when the last close completes or a hangup finishes IFF the
* port was initialized. Do not use to free resources. Turn off the device
* only. Called under the port mutex to serialize against @activate and
* @shutdown.
* @activate: called under the port mutex from tty_port_open(), serialized using
* the port mutex. Supposed to turn on the device.
*
* FIXME: long term getting the tty argument *out* of this would be good
* for consoles.
*
* @destruct: called on the final put of a port. Free resources, possibly incl.
* the port itself.
*/
struct tty_port_operations {
bool (*carrier_raised)(struct tty_port *port);
void (*dtr_rts)(struct tty_port *port, bool active);
void (*shutdown)(struct tty_port *port);
int (*activate)(struct tty_port *port, struct tty_struct *tty);
void (*destruct)(struct tty_port *port);
};
struct tty_port_client_operations {
size_t (*receive_buf)(struct tty_port *port, const u8 *cp, const u8 *fp,
size_t count);
void (*lookahead_buf)(struct tty_port *port, const u8 *cp,
const u8 *fp, size_t count);
void (*write_wakeup)(struct tty_port *port);
};
extern const struct tty_port_client_operations tty_port_default_client_ops;
/**
* struct tty_port -- port level information
*
* @buf: buffer for this port, locked internally
* @tty: back pointer to &struct tty_struct, valid only if the tty is open. Use
* tty_port_tty_get() to obtain it (and tty_kref_put() to release).
* @itty: internal back pointer to &struct tty_struct. Avoid this. It should be
* eliminated in the long term.
* @ops: tty port operations (like activate, shutdown), see &struct
* tty_port_operations
* @client_ops: tty port client operations (like receive_buf, write_wakeup).
* By default, tty_port_default_client_ops is used.
* @lock: lock protecting @tty
* @blocked_open: # of procs waiting for open in tty_port_block_til_ready()
* @count: usage count
* @open_wait: open waiters queue (waiting e.g. for a carrier)
* @delta_msr_wait: modem status change queue (waiting for MSR changes)
* @flags: user TTY flags (%ASYNC_)
* @iflags: internal flags (%TTY_PORT_)
* @console: when set, the port is a console
* @mutex: locking, for open, shutdown and other port operations
* @buf_mutex: @xmit_buf alloc lock
* @xmit_buf: optional xmit buffer used by some drivers
* @xmit_fifo: optional xmit buffer used by some drivers
* @close_delay: delay in jiffies to wait when closing the port
* @closing_wait: delay in jiffies for output to be sent before closing
* @drain_delay: set to zero if no pure time based drain is needed else set to
* size of fifo
* @kref: references counter. Reaching zero calls @ops->destruct() if non-%NULL
* or frees the port otherwise.
* @client_data: pointer to private data, for @client_ops
*
* Each device keeps its own port level information. &struct tty_port was
* introduced as a common structure for such information. As every TTY device
* shall have a backing tty_port structure, every driver can use these members.
*
* The tty port has a different lifetime to the tty so must be kept apart.
* In addition be careful as tty -> port mappings are valid for the life
* of the tty object but in many cases port -> tty mappings are valid only
* until a hangup so don't use the wrong path.
*
* Tty port shall be initialized by tty_port_init() and shut down either by
* tty_port_destroy() (refcounting not used), or tty_port_put() (refcounting).
*
* There is a lot of helpers around &struct tty_port too. To name the most
* significant ones: tty_port_open(), tty_port_close() (or
* tty_port_close_start() and tty_port_close_end() separately if need be), and
* tty_port_hangup(). These call @ops->activate() and @ops->shutdown() as
* needed.
*/
struct tty_port {
struct tty_bufhead buf;
struct tty_struct *tty;
struct tty_struct *itty;
const struct tty_port_operations *ops;
const struct tty_port_client_operations *client_ops;
spinlock_t lock;
int blocked_open;
int count;
wait_queue_head_t open_wait;
wait_queue_head_t delta_msr_wait;
unsigned long flags;
unsigned long iflags;
unsigned char console:1;
struct mutex mutex;
struct mutex buf_mutex;
u8 *xmit_buf;
DECLARE_KFIFO_PTR(xmit_fifo, u8);
unsigned int close_delay;
unsigned int closing_wait;
int drain_delay;
struct kref kref;
void *client_data;
};
/* tty_port::iflags bits -- use atomic bit ops */
#define TTY_PORT_INITIALIZED 0 /* device is initialized */
#define TTY_PORT_SUSPENDED 1 /* device is suspended */
#define TTY_PORT_ACTIVE 2 /* device is open */
/*
* uart drivers: use the uart_port::status field and the UPSTAT_* defines
* for s/w-based flow control steering and carrier detection status
*/
#define TTY_PORT_CTS_FLOW 3 /* h/w flow control enabled */
#define TTY_PORT_CHECK_CD 4 /* carrier detect enabled */
#define TTY_PORT_KOPENED 5 /* device exclusively opened by
kernel */
void tty_port_init(struct tty_port *port);
void tty_port_link_device(struct tty_port *port, struct tty_driver *driver,
unsigned index);
struct device *tty_port_register_device(struct tty_port *port,
struct tty_driver *driver, unsigned index,
struct device *device);
struct device *tty_port_register_device_attr(struct tty_port *port,
struct tty_driver *driver, unsigned index,
struct device *device, void *drvdata,
const struct attribute_group **attr_grp);
struct device *tty_port_register_device_serdev(struct tty_port *port,
struct tty_driver *driver, unsigned index,
struct device *host, struct device *parent);
struct device *tty_port_register_device_attr_serdev(struct tty_port *port,
struct tty_driver *driver, unsigned index,
struct device *host, struct device *parent, void *drvdata,
const struct attribute_group **attr_grp);
void tty_port_unregister_device(struct tty_port *port,
struct tty_driver *driver, unsigned index);
int tty_port_alloc_xmit_buf(struct tty_port *port);
void tty_port_free_xmit_buf(struct tty_port *port);
void tty_port_destroy(struct tty_port *port);
void tty_port_put(struct tty_port *port);
static inline struct tty_port *tty_port_get(struct tty_port *port)
{
if (port && kref_get_unless_zero(&port->kref))
return port;
return NULL;
}
/* If the cts flow control is enabled, return true. */
static inline bool tty_port_cts_enabled(const struct tty_port *port)
{
return test_bit(TTY_PORT_CTS_FLOW, &port->iflags);
}
static inline void tty_port_set_cts_flow(struct tty_port *port, bool val)
{
assign_bit(TTY_PORT_CTS_FLOW, &port->iflags, val);
}
static inline bool tty_port_active(const struct tty_port *port)
{
return test_bit(TTY_PORT_ACTIVE, &port->iflags);
}
static inline void tty_port_set_active(struct tty_port *port, bool val)
{
assign_bit(TTY_PORT_ACTIVE, &port->iflags, val);
}
static inline bool tty_port_check_carrier(const struct tty_port *port)
{
return test_bit(TTY_PORT_CHECK_CD, &port->iflags);
}
static inline void tty_port_set_check_carrier(struct tty_port *port, bool val)
{
assign_bit(TTY_PORT_CHECK_CD, &port->iflags, val);
}
static inline bool tty_port_suspended(const struct tty_port *port)
{
return test_bit(TTY_PORT_SUSPENDED, &port->iflags);
}
static inline void tty_port_set_suspended(struct tty_port *port, bool val)
{
assign_bit(TTY_PORT_SUSPENDED, &port->iflags, val);
}
static inline bool tty_port_initialized(const struct tty_port *port)
{
return test_bit(TTY_PORT_INITIALIZED, &port->iflags);
}
static inline void tty_port_set_initialized(struct tty_port *port, bool val)
{
assign_bit(TTY_PORT_INITIALIZED, &port->iflags, val);
}
static inline bool tty_port_kopened(const struct tty_port *port)
{
return test_bit(TTY_PORT_KOPENED, &port->iflags);
}
static inline void tty_port_set_kopened(struct tty_port *port, bool val)
{
assign_bit(TTY_PORT_KOPENED, &port->iflags, val);
}
struct tty_struct *tty_port_tty_get(struct tty_port *port);
void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty);
bool tty_port_carrier_raised(struct tty_port *port);
void tty_port_raise_dtr_rts(struct tty_port *port);
void tty_port_lower_dtr_rts(struct tty_port *port);
void tty_port_hangup(struct tty_port *port);
void tty_port_tty_hangup(struct tty_port *port, bool check_clocal);
void tty_port_tty_wakeup(struct tty_port *port);
int tty_port_block_til_ready(struct tty_port *port, struct tty_struct *tty,
struct file *filp);
int tty_port_close_start(struct tty_port *port, struct tty_struct *tty,
struct file *filp);
void tty_port_close_end(struct tty_port *port, struct tty_struct *tty);
void tty_port_close(struct tty_port *port, struct tty_struct *tty,
struct file *filp);
int tty_port_install(struct tty_port *port, struct tty_driver *driver,
struct tty_struct *tty);
int tty_port_open(struct tty_port *port, struct tty_struct *tty,
struct file *filp);
static inline int tty_port_users(struct tty_port *port)
{
return port->count + port->blocked_open;
}
#endif