1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _LINUX_TTY_PORT_H 3 #define _LINUX_TTY_PORT_H 4 5 #include <linux/kfifo.h> 6 #include <linux/kref.h> 7 #include <linux/mutex.h> 8 #include <linux/tty_buffer.h> 9 #include <linux/tty_driver.h> 10 #include <linux/wait.h> 11 12 struct attribute_group; 13 struct tty_port; 14 struct tty_struct; 15 16 /** 17 * struct tty_port_operations -- operations on tty_port 18 * @carrier_raised: return true if the carrier is raised on @port 19 * @dtr_rts: raise the DTR line if @active is true, otherwise lower DTR 20 * @shutdown: called when the last close completes or a hangup finishes IFF the 21 * port was initialized. Do not use to free resources. Turn off the device 22 * only. Called under the port mutex to serialize against @activate and 23 * @shutdown. 24 * @activate: called under the port mutex from tty_port_open(), serialized using 25 * the port mutex. Supposed to turn on the device. 26 * 27 * FIXME: long term getting the tty argument *out* of this would be good 28 * for consoles. 29 * 30 * @destruct: called on the final put of a port. Free resources, possibly incl. 31 * the port itself. 32 */ 33 struct tty_port_operations { 34 bool (*carrier_raised)(struct tty_port *port); 35 void (*dtr_rts)(struct tty_port *port, bool active); 36 void (*shutdown)(struct tty_port *port); 37 int (*activate)(struct tty_port *port, struct tty_struct *tty); 38 void (*destruct)(struct tty_port *port); 39 }; 40 41 struct tty_port_client_operations { 42 size_t (*receive_buf)(struct tty_port *port, const u8 *cp, const u8 *fp, 43 size_t count); 44 void (*lookahead_buf)(struct tty_port *port, const u8 *cp, 45 const u8 *fp, size_t count); 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 /** 52 * struct tty_port -- port level information 53 * 54 * @buf: buffer for this port, locked internally 55 * @tty: back pointer to &struct tty_struct, valid only if the tty is open. Use 56 * tty_port_tty_get() to obtain it (and tty_kref_put() to release). 57 * @itty: internal back pointer to &struct tty_struct. Avoid this. It should be 58 * eliminated in the long term. 59 * @ops: tty port operations (like activate, shutdown), see &struct 60 * tty_port_operations 61 * @client_ops: tty port client operations (like receive_buf, write_wakeup). 62 * By default, tty_port_default_client_ops is used. 63 * @lock: lock protecting @tty 64 * @blocked_open: # of procs waiting for open in tty_port_block_til_ready() 65 * @count: usage count 66 * @open_wait: open waiters queue (waiting e.g. for a carrier) 67 * @delta_msr_wait: modem status change queue (waiting for MSR changes) 68 * @flags: user TTY flags (%ASYNC_) 69 * @iflags: internal flags (%TTY_PORT_) 70 * @console: when set, the port is a console 71 * @mutex: locking, for open, shutdown and other port operations 72 * @buf_mutex: @xmit_buf alloc lock 73 * @xmit_buf: optional xmit buffer used by some drivers 74 * @xmit_fifo: optional xmit buffer used by some drivers 75 * @close_delay: delay in jiffies to wait when closing the port 76 * @closing_wait: delay in jiffies for output to be sent before closing 77 * @drain_delay: set to zero if no pure time based drain is needed else set to 78 * size of fifo 79 * @kref: references counter. Reaching zero calls @ops->destruct() if non-%NULL 80 * or frees the port otherwise. 81 * @client_data: pointer to private data, for @client_ops 82 * 83 * Each device keeps its own port level information. &struct tty_port was 84 * introduced as a common structure for such information. As every TTY device 85 * shall have a backing tty_port structure, every driver can use these members. 86 * 87 * The tty port has a different lifetime to the tty so must be kept apart. 88 * In addition be careful as tty -> port mappings are valid for the life 89 * of the tty object but in many cases port -> tty mappings are valid only 90 * until a hangup so don't use the wrong path. 91 * 92 * Tty port shall be initialized by tty_port_init() and shut down either by 93 * tty_port_destroy() (refcounting not used), or tty_port_put() (refcounting). 94 * 95 * There is a lot of helpers around &struct tty_port too. To name the most 96 * significant ones: tty_port_open(), tty_port_close() (or 97 * tty_port_close_start() and tty_port_close_end() separately if need be), and 98 * tty_port_hangup(). These call @ops->activate() and @ops->shutdown() as 99 * needed. 100 */ 101 struct tty_port { 102 struct tty_bufhead buf; 103 struct tty_struct *tty; 104 struct tty_struct *itty; 105 const struct tty_port_operations *ops; 106 const struct tty_port_client_operations *client_ops; 107 spinlock_t lock; 108 int blocked_open; 109 int count; 110 wait_queue_head_t open_wait; 111 wait_queue_head_t delta_msr_wait; 112 unsigned long flags; 113 unsigned long iflags; 114 unsigned char console:1; 115 struct mutex mutex; 116 struct mutex buf_mutex; 117 u8 *xmit_buf; 118 DECLARE_KFIFO_PTR(xmit_fifo, u8); 119 unsigned int close_delay; 120 unsigned int closing_wait; 121 int drain_delay; 122 struct kref kref; 123 void *client_data; 124 }; 125 126 /* tty_port::iflags bits -- use atomic bit ops */ 127 #define TTY_PORT_INITIALIZED 0 /* device is initialized */ 128 #define TTY_PORT_SUSPENDED 1 /* device is suspended */ 129 #define TTY_PORT_ACTIVE 2 /* device is open */ 130 131 /* 132 * uart drivers: use the uart_port::status field and the UPSTAT_* defines 133 * for s/w-based flow control steering and carrier detection status 134 */ 135 #define TTY_PORT_CTS_FLOW 3 /* h/w flow control enabled */ 136 #define TTY_PORT_CHECK_CD 4 /* carrier detect enabled */ 137 #define TTY_PORT_KOPENED 5 /* device exclusively opened by 138 kernel */ 139 140 void tty_port_init(struct tty_port *port); 141 void tty_port_link_wq(struct tty_port *port, struct workqueue_struct *flip_wq); 142 void tty_port_link_device(struct tty_port *port, struct tty_driver *driver, 143 unsigned index); 144 struct device *tty_port_register_device(struct tty_port *port, 145 struct tty_driver *driver, unsigned index, 146 struct device *device); 147 struct device *tty_port_register_device_attr(struct tty_port *port, 148 struct tty_driver *driver, unsigned index, 149 struct device *device, void *drvdata, 150 const struct attribute_group **attr_grp); 151 struct device *tty_port_register_device_attr_serdev(struct tty_port *port, 152 struct tty_driver *driver, unsigned index, 153 struct device *host, struct device *parent, void *drvdata, 154 const struct attribute_group **attr_grp); 155 void tty_port_unregister_device(struct tty_port *port, 156 struct tty_driver *driver, unsigned index); 157 int tty_port_alloc_xmit_buf(struct tty_port *port); 158 void tty_port_free_xmit_buf(struct tty_port *port); 159 void tty_port_destroy(struct tty_port *port); 160 void tty_port_put(struct tty_port *port); 161 162 static inline struct tty_port *tty_port_get(struct tty_port *port) 163 { 164 if (port && kref_get_unless_zero(&port->kref)) 165 return port; 166 return NULL; 167 } 168 169 /* 170 * Never overwrite the workqueue set by tty_port_link_wq(). 171 * No effect when %TTY_DRIVER_NO_WORKQUEUE is set, as driver->flip_wq is 172 * %NULL. 173 */ 174 static inline void tty_port_link_driver_wq(struct tty_port *port, 175 struct tty_driver *driver) 176 { 177 if (!port->buf.flip_wq) 178 tty_port_link_wq(port, driver->flip_wq); 179 } 180 181 /* If the cts flow control is enabled, return true. */ 182 static inline bool tty_port_cts_enabled(const struct tty_port *port) 183 { 184 return test_bit(TTY_PORT_CTS_FLOW, &port->iflags); 185 } 186 187 static inline void tty_port_set_cts_flow(struct tty_port *port, bool val) 188 { 189 assign_bit(TTY_PORT_CTS_FLOW, &port->iflags, val); 190 } 191 192 static inline bool tty_port_active(const struct tty_port *port) 193 { 194 return test_bit(TTY_PORT_ACTIVE, &port->iflags); 195 } 196 197 static inline void tty_port_set_active(struct tty_port *port, bool val) 198 { 199 assign_bit(TTY_PORT_ACTIVE, &port->iflags, val); 200 } 201 202 static inline bool tty_port_check_carrier(const struct tty_port *port) 203 { 204 return test_bit(TTY_PORT_CHECK_CD, &port->iflags); 205 } 206 207 static inline void tty_port_set_check_carrier(struct tty_port *port, bool val) 208 { 209 assign_bit(TTY_PORT_CHECK_CD, &port->iflags, val); 210 } 211 212 static inline bool tty_port_suspended(const struct tty_port *port) 213 { 214 return test_bit(TTY_PORT_SUSPENDED, &port->iflags); 215 } 216 217 static inline void tty_port_set_suspended(struct tty_port *port, bool val) 218 { 219 assign_bit(TTY_PORT_SUSPENDED, &port->iflags, val); 220 } 221 222 static inline bool tty_port_initialized(const struct tty_port *port) 223 { 224 return test_bit(TTY_PORT_INITIALIZED, &port->iflags); 225 } 226 227 static inline void tty_port_set_initialized(struct tty_port *port, bool val) 228 { 229 assign_bit(TTY_PORT_INITIALIZED, &port->iflags, val); 230 } 231 232 static inline bool tty_port_kopened(const struct tty_port *port) 233 { 234 return test_bit(TTY_PORT_KOPENED, &port->iflags); 235 } 236 237 static inline void tty_port_set_kopened(struct tty_port *port, bool val) 238 { 239 assign_bit(TTY_PORT_KOPENED, &port->iflags, val); 240 } 241 242 struct tty_struct *tty_port_tty_get(struct tty_port *port); 243 void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty); 244 bool tty_port_carrier_raised(struct tty_port *port); 245 void tty_port_raise_dtr_rts(struct tty_port *port); 246 void tty_port_lower_dtr_rts(struct tty_port *port); 247 void tty_port_hangup(struct tty_port *port); 248 void tty_port_tty_hangup(struct tty_port *port, bool check_clocal); 249 void tty_port_tty_vhangup(struct tty_port *port); 250 void tty_port_tty_wakeup(struct tty_port *port); 251 int tty_port_block_til_ready(struct tty_port *port, struct tty_struct *tty, 252 struct file *filp); 253 int tty_port_close_start(struct tty_port *port, struct tty_struct *tty, 254 struct file *filp); 255 void tty_port_close_end(struct tty_port *port, struct tty_struct *tty); 256 void tty_port_close(struct tty_port *port, struct tty_struct *tty, 257 struct file *filp); 258 int tty_port_install(struct tty_port *port, struct tty_driver *driver, 259 struct tty_struct *tty); 260 int tty_port_open(struct tty_port *port, struct tty_struct *tty, 261 struct file *filp); 262 263 static inline int tty_port_users(struct tty_port *port) 264 { 265 return port->count + port->blocked_open; 266 } 267 268 #ifdef CONFIG_TTY 269 void tty_kref_put(struct tty_struct *tty); 270 __DEFINE_CLASS_IS_CONDITIONAL(tty_port_tty, true); 271 __DEFINE_UNLOCK_GUARD(tty_port_tty, struct tty_struct, tty_kref_put(_T->lock)); 272 static inline class_tty_port_tty_t class_tty_port_tty_constructor(struct tty_port *tport) 273 { 274 class_tty_port_tty_t _t = { 275 .lock = tty_port_tty_get(tport), 276 }; 277 return _t; 278 } 279 #define scoped_tty() ((struct tty_struct *)(__guard_ptr(tty_port_tty)(&scope))) 280 #endif 281 282 #endif 283