1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_TTY_PORT_H
3 #define _LINUX_TTY_PORT_H
4
5 #include <linux/kref.h>
6 #include <linux/mutex.h>
7 #include <linux/tty_buffer.h>
8 #include <linux/wait.h>
9
10 /*
11 * Port level information. Each device keeps its own port level information
12 * so provide a common structure for those ports wanting to use common support
13 * routines.
14 *
15 * The tty port has a different lifetime to the tty so must be kept apart.
16 * In addition be careful as tty -> port mappings are valid for the life
17 * of the tty object but in many cases port -> tty mappings are valid only
18 * until a hangup so don't use the wrong path.
19 */
20
21 struct attribute_group;
22 struct tty_driver;
23 struct tty_port;
24 struct tty_struct;
25
26 struct tty_port_operations {
27 /* Return 1 if the carrier is raised */
28 int (*carrier_raised)(struct tty_port *port);
29 /* Control the DTR line */
30 void (*dtr_rts)(struct tty_port *port, int raise);
31 /* Called when the last close completes or a hangup finishes
32 IFF the port was initialized. Do not use to free resources. Called
33 under the port mutex to serialize against activate/shutdowns */
34 void (*shutdown)(struct tty_port *port);
35 /* Called under the port mutex from tty_port_open, serialized using
36 the port mutex */
37 /* FIXME: long term getting the tty argument *out* of this would be
38 good for consoles */
39 int (*activate)(struct tty_port *port, struct tty_struct *tty);
40 /* Called on the final put of a port */
41 void (*destruct)(struct tty_port *port);
42 };
43
44 struct tty_port_client_operations {
45 int (*receive_buf)(struct tty_port *port, const unsigned char *, const unsigned char *, size_t);
46 void (*write_wakeup)(struct tty_port *port);
47 };
48
49 extern const struct tty_port_client_operations tty_port_default_client_ops;
50
51 struct tty_port {
52 struct tty_bufhead buf; /* Locked internally */
53 struct tty_struct *tty; /* Back pointer */
54 struct tty_struct *itty; /* internal back ptr */
55 const struct tty_port_operations *ops; /* Port operations */
56 const struct tty_port_client_operations *client_ops; /* Port client operations */
57 spinlock_t lock; /* Lock protecting tty field */
58 int blocked_open; /* Waiting to open */
59 int count; /* Usage count */
60 wait_queue_head_t open_wait; /* Open waiters */
61 wait_queue_head_t delta_msr_wait; /* Modem status change */
62 unsigned long flags; /* User TTY flags ASYNC_ */
63 unsigned long iflags; /* Internal flags TTY_PORT_ */
64 unsigned char console:1; /* port is a console */
65 struct mutex mutex; /* Locking */
66 struct mutex buf_mutex; /* Buffer alloc lock */
67 unsigned char *xmit_buf; /* Optional buffer */
68 unsigned int close_delay; /* Close port delay */
69 unsigned int closing_wait; /* Delay for output */
70 int drain_delay; /* Set to zero if no pure time
71 based drain is needed else
72 set to size of fifo */
73 struct kref kref; /* Ref counter */
74 void *client_data;
75 };
76
77 /* tty_port::iflags bits -- use atomic bit ops */
78 #define TTY_PORT_INITIALIZED 0 /* device is initialized */
79 #define TTY_PORT_SUSPENDED 1 /* device is suspended */
80 #define TTY_PORT_ACTIVE 2 /* device is open */
81
82 /*
83 * uart drivers: use the uart_port::status field and the UPSTAT_* defines
84 * for s/w-based flow control steering and carrier detection status
85 */
86 #define TTY_PORT_CTS_FLOW 3 /* h/w flow control enabled */
87 #define TTY_PORT_CHECK_CD 4 /* carrier detect enabled */
88 #define TTY_PORT_KOPENED 5 /* device exclusively opened by
89 kernel */
90
91 void tty_port_init(struct tty_port *port);
92 void tty_port_link_device(struct tty_port *port, struct tty_driver *driver,
93 unsigned index);
94 struct device *tty_port_register_device(struct tty_port *port,
95 struct tty_driver *driver, unsigned index,
96 struct device *device);
97 struct device *tty_port_register_device_attr(struct tty_port *port,
98 struct tty_driver *driver, unsigned index,
99 struct device *device, void *drvdata,
100 const struct attribute_group **attr_grp);
101 struct device *tty_port_register_device_serdev(struct tty_port *port,
102 struct tty_driver *driver, unsigned index,
103 struct device *device);
104 struct device *tty_port_register_device_attr_serdev(struct tty_port *port,
105 struct tty_driver *driver, unsigned index,
106 struct device *device, void *drvdata,
107 const struct attribute_group **attr_grp);
108 void tty_port_unregister_device(struct tty_port *port,
109 struct tty_driver *driver, unsigned index);
110 int tty_port_alloc_xmit_buf(struct tty_port *port);
111 void tty_port_free_xmit_buf(struct tty_port *port);
112 void tty_port_destroy(struct tty_port *port);
113 void tty_port_put(struct tty_port *port);
114
tty_port_get(struct tty_port * port)115 static inline struct tty_port *tty_port_get(struct tty_port *port)
116 {
117 if (port && kref_get_unless_zero(&port->kref))
118 return port;
119 return NULL;
120 }
121
122 /* If the cts flow control is enabled, return true. */
tty_port_cts_enabled(const struct tty_port * port)123 static inline bool tty_port_cts_enabled(const struct tty_port *port)
124 {
125 return test_bit(TTY_PORT_CTS_FLOW, &port->iflags);
126 }
127
tty_port_set_cts_flow(struct tty_port * port,bool val)128 static inline void tty_port_set_cts_flow(struct tty_port *port, bool val)
129 {
130 assign_bit(TTY_PORT_CTS_FLOW, &port->iflags, val);
131 }
132
tty_port_active(const struct tty_port * port)133 static inline bool tty_port_active(const struct tty_port *port)
134 {
135 return test_bit(TTY_PORT_ACTIVE, &port->iflags);
136 }
137
tty_port_set_active(struct tty_port * port,bool val)138 static inline void tty_port_set_active(struct tty_port *port, bool val)
139 {
140 assign_bit(TTY_PORT_ACTIVE, &port->iflags, val);
141 }
142
tty_port_check_carrier(const struct tty_port * port)143 static inline bool tty_port_check_carrier(const struct tty_port *port)
144 {
145 return test_bit(TTY_PORT_CHECK_CD, &port->iflags);
146 }
147
tty_port_set_check_carrier(struct tty_port * port,bool val)148 static inline void tty_port_set_check_carrier(struct tty_port *port, bool val)
149 {
150 assign_bit(TTY_PORT_CHECK_CD, &port->iflags, val);
151 }
152
tty_port_suspended(const struct tty_port * port)153 static inline bool tty_port_suspended(const struct tty_port *port)
154 {
155 return test_bit(TTY_PORT_SUSPENDED, &port->iflags);
156 }
157
tty_port_set_suspended(struct tty_port * port,bool val)158 static inline void tty_port_set_suspended(struct tty_port *port, bool val)
159 {
160 assign_bit(TTY_PORT_SUSPENDED, &port->iflags, val);
161 }
162
tty_port_initialized(const struct tty_port * port)163 static inline bool tty_port_initialized(const struct tty_port *port)
164 {
165 return test_bit(TTY_PORT_INITIALIZED, &port->iflags);
166 }
167
tty_port_set_initialized(struct tty_port * port,bool val)168 static inline void tty_port_set_initialized(struct tty_port *port, bool val)
169 {
170 assign_bit(TTY_PORT_INITIALIZED, &port->iflags, val);
171 }
172
tty_port_kopened(const struct tty_port * port)173 static inline bool tty_port_kopened(const struct tty_port *port)
174 {
175 return test_bit(TTY_PORT_KOPENED, &port->iflags);
176 }
177
tty_port_set_kopened(struct tty_port * port,bool val)178 static inline void tty_port_set_kopened(struct tty_port *port, bool val)
179 {
180 assign_bit(TTY_PORT_KOPENED, &port->iflags, val);
181 }
182
183 struct tty_struct *tty_port_tty_get(struct tty_port *port);
184 void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty);
185 int tty_port_carrier_raised(struct tty_port *port);
186 void tty_port_raise_dtr_rts(struct tty_port *port);
187 void tty_port_lower_dtr_rts(struct tty_port *port);
188 void tty_port_hangup(struct tty_port *port);
189 void tty_port_tty_hangup(struct tty_port *port, bool check_clocal);
190 void tty_port_tty_wakeup(struct tty_port *port);
191 int tty_port_block_til_ready(struct tty_port *port, struct tty_struct *tty,
192 struct file *filp);
193 int tty_port_close_start(struct tty_port *port, struct tty_struct *tty,
194 struct file *filp);
195 void tty_port_close_end(struct tty_port *port, struct tty_struct *tty);
196 void tty_port_close(struct tty_port *port, struct tty_struct *tty,
197 struct file *filp);
198 int tty_port_install(struct tty_port *port, struct tty_driver *driver,
199 struct tty_struct *tty);
200 int tty_port_open(struct tty_port *port, struct tty_struct *tty,
201 struct file *filp);
202
tty_port_users(struct tty_port * port)203 static inline int tty_port_users(struct tty_port *port)
204 {
205 return port->count + port->blocked_open;
206 }
207
208 #endif
209