1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3 * linux/drivers/char/serial_core.h
4 *
5 * Copyright (C) 2000 Deep Blue Solutions Ltd.
6 */
7 #ifndef LINUX_SERIAL_CORE_H
8 #define LINUX_SERIAL_CORE_H
9
10 #include <linux/bitops.h>
11 #include <linux/compiler.h>
12 #include <linux/console.h>
13 #include <linux/interrupt.h>
14 #include <linux/circ_buf.h>
15 #include <linux/spinlock.h>
16 #include <linux/sched.h>
17 #include <linux/tty.h>
18 #include <linux/mutex.h>
19 #include <linux/sysrq.h>
20 #include <linux/android_kabi.h>
21 #include <uapi/linux/serial_core.h>
22
23 #ifdef CONFIG_SERIAL_CORE_CONSOLE
24 #define uart_console(port) \
25 ((port)->cons && (port)->cons->index == (port)->line)
26 #else
27 #define uart_console(port) ({ (void)port; 0; })
28 #endif
29
30 struct uart_port;
31 struct serial_struct;
32 struct device;
33 struct gpio_desc;
34
35 /*
36 * This structure describes all the operations that can be done on the
37 * physical hardware. See Documentation/driver-api/serial/driver.rst for details.
38 */
39 struct uart_ops {
40 unsigned int (*tx_empty)(struct uart_port *);
41 void (*set_mctrl)(struct uart_port *, unsigned int mctrl);
42 unsigned int (*get_mctrl)(struct uart_port *);
43 void (*stop_tx)(struct uart_port *);
44 void (*start_tx)(struct uart_port *);
45 void (*throttle)(struct uart_port *);
46 void (*unthrottle)(struct uart_port *);
47 void (*send_xchar)(struct uart_port *, char ch);
48 void (*stop_rx)(struct uart_port *);
49 void (*enable_ms)(struct uart_port *);
50 void (*break_ctl)(struct uart_port *, int ctl);
51 int (*startup)(struct uart_port *);
52 void (*shutdown)(struct uart_port *);
53 void (*flush_buffer)(struct uart_port *);
54 void (*set_termios)(struct uart_port *, struct ktermios *new,
55 struct ktermios *old);
56 void (*set_ldisc)(struct uart_port *, struct ktermios *);
57 void (*pm)(struct uart_port *, unsigned int state,
58 unsigned int oldstate);
59
60 /*
61 * Return a string describing the type of the port
62 */
63 const char *(*type)(struct uart_port *);
64
65 /*
66 * Release IO and memory resources used by the port.
67 * This includes iounmap if necessary.
68 */
69 void (*release_port)(struct uart_port *);
70
71 /*
72 * Request IO and memory resources used by the port.
73 * This includes iomapping the port if necessary.
74 */
75 int (*request_port)(struct uart_port *);
76 void (*config_port)(struct uart_port *, int);
77 int (*verify_port)(struct uart_port *, struct serial_struct *);
78 int (*ioctl)(struct uart_port *, unsigned int, unsigned long);
79 #ifdef CONFIG_CONSOLE_POLL
80 int (*poll_init)(struct uart_port *);
81 void (*poll_put_char)(struct uart_port *, unsigned char);
82 int (*poll_get_char)(struct uart_port *);
83 #endif
84
85 ANDROID_KABI_RESERVE(1);
86 ANDROID_KABI_RESERVE(2);
87 };
88
89 #define NO_POLL_CHAR 0x00ff0000
90 #define UART_CONFIG_TYPE (1 << 0)
91 #define UART_CONFIG_IRQ (1 << 1)
92
93 struct uart_icount {
94 __u32 cts;
95 __u32 dsr;
96 __u32 rng;
97 __u32 dcd;
98 __u32 rx;
99 __u32 tx;
100 __u32 frame;
101 __u32 overrun;
102 __u32 parity;
103 __u32 brk;
104 __u32 buf_overrun;
105 };
106
107 typedef unsigned int __bitwise upf_t;
108 typedef unsigned int __bitwise upstat_t;
109
110 struct uart_port {
111 spinlock_t lock; /* port lock */
112 unsigned long iobase; /* in/out[bwl] */
113 unsigned char __iomem *membase; /* read/write[bwl] */
114 unsigned int (*serial_in)(struct uart_port *, int);
115 void (*serial_out)(struct uart_port *, int, int);
116 void (*set_termios)(struct uart_port *,
117 struct ktermios *new,
118 struct ktermios *old);
119 void (*set_ldisc)(struct uart_port *,
120 struct ktermios *);
121 unsigned int (*get_mctrl)(struct uart_port *);
122 void (*set_mctrl)(struct uart_port *, unsigned int);
123 unsigned int (*get_divisor)(struct uart_port *,
124 unsigned int baud,
125 unsigned int *frac);
126 void (*set_divisor)(struct uart_port *,
127 unsigned int baud,
128 unsigned int quot,
129 unsigned int quot_frac);
130 int (*startup)(struct uart_port *port);
131 void (*shutdown)(struct uart_port *port);
132 void (*throttle)(struct uart_port *port);
133 void (*unthrottle)(struct uart_port *port);
134 int (*handle_irq)(struct uart_port *);
135 void (*pm)(struct uart_port *, unsigned int state,
136 unsigned int old);
137 void (*handle_break)(struct uart_port *);
138 int (*rs485_config)(struct uart_port *,
139 struct serial_rs485 *rs485);
140 int (*iso7816_config)(struct uart_port *,
141 struct serial_iso7816 *iso7816);
142 unsigned int irq; /* irq number */
143 unsigned long irqflags; /* irq flags */
144 unsigned int uartclk; /* base uart clock */
145 unsigned int fifosize; /* tx fifo size */
146 unsigned char x_char; /* xon/xoff char */
147 unsigned char regshift; /* reg offset shift */
148 unsigned char iotype; /* io access style */
149 unsigned char quirks; /* internal quirks */
150
151 #define UPIO_PORT (SERIAL_IO_PORT) /* 8b I/O port access */
152 #define UPIO_HUB6 (SERIAL_IO_HUB6) /* Hub6 ISA card */
153 #define UPIO_MEM (SERIAL_IO_MEM) /* driver-specific */
154 #define UPIO_MEM32 (SERIAL_IO_MEM32) /* 32b little endian */
155 #define UPIO_AU (SERIAL_IO_AU) /* Au1x00 and RT288x type IO */
156 #define UPIO_TSI (SERIAL_IO_TSI) /* Tsi108/109 type IO */
157 #define UPIO_MEM32BE (SERIAL_IO_MEM32BE) /* 32b big endian */
158 #define UPIO_MEM16 (SERIAL_IO_MEM16) /* 16b little endian */
159
160 /* quirks must be updated while holding port mutex */
161 #define UPQ_NO_TXEN_TEST BIT(0)
162
163 unsigned int read_status_mask; /* driver specific */
164 unsigned int ignore_status_mask; /* driver specific */
165 struct uart_state *state; /* pointer to parent state */
166 struct uart_icount icount; /* statistics */
167
168 struct console *cons; /* struct console, if any */
169 /* flags must be updated while holding port mutex */
170 upf_t flags;
171
172 /*
173 * These flags must be equivalent to the flags defined in
174 * include/uapi/linux/tty_flags.h which are the userspace definitions
175 * assigned from the serial_struct flags in uart_set_info()
176 * [for bit definitions in the UPF_CHANGE_MASK]
177 *
178 * Bits [0..UPF_LAST_USER] are userspace defined/visible/changeable
179 * The remaining bits are serial-core specific and not modifiable by
180 * userspace.
181 */
182 #define UPF_FOURPORT ((__force upf_t) ASYNC_FOURPORT /* 1 */ )
183 #define UPF_SAK ((__force upf_t) ASYNC_SAK /* 2 */ )
184 #define UPF_SPD_HI ((__force upf_t) ASYNC_SPD_HI /* 4 */ )
185 #define UPF_SPD_VHI ((__force upf_t) ASYNC_SPD_VHI /* 5 */ )
186 #define UPF_SPD_CUST ((__force upf_t) ASYNC_SPD_CUST /* 0x0030 */ )
187 #define UPF_SPD_WARP ((__force upf_t) ASYNC_SPD_WARP /* 0x1010 */ )
188 #define UPF_SPD_MASK ((__force upf_t) ASYNC_SPD_MASK /* 0x1030 */ )
189 #define UPF_SKIP_TEST ((__force upf_t) ASYNC_SKIP_TEST /* 6 */ )
190 #define UPF_AUTO_IRQ ((__force upf_t) ASYNC_AUTO_IRQ /* 7 */ )
191 #define UPF_HARDPPS_CD ((__force upf_t) ASYNC_HARDPPS_CD /* 11 */ )
192 #define UPF_SPD_SHI ((__force upf_t) ASYNC_SPD_SHI /* 12 */ )
193 #define UPF_LOW_LATENCY ((__force upf_t) ASYNC_LOW_LATENCY /* 13 */ )
194 #define UPF_BUGGY_UART ((__force upf_t) ASYNC_BUGGY_UART /* 14 */ )
195 #define UPF_MAGIC_MULTIPLIER ((__force upf_t) ASYNC_MAGIC_MULTIPLIER /* 16 */ )
196
197 #define UPF_NO_THRE_TEST ((__force upf_t) (1 << 19))
198 /* Port has hardware-assisted h/w flow control */
199 #define UPF_AUTO_CTS ((__force upf_t) (1 << 20))
200 #define UPF_AUTO_RTS ((__force upf_t) (1 << 21))
201 #define UPF_HARD_FLOW ((__force upf_t) (UPF_AUTO_CTS | UPF_AUTO_RTS))
202 /* Port has hardware-assisted s/w flow control */
203 #define UPF_SOFT_FLOW ((__force upf_t) (1 << 22))
204 #define UPF_CONS_FLOW ((__force upf_t) (1 << 23))
205 #define UPF_SHARE_IRQ ((__force upf_t) (1 << 24))
206 #define UPF_EXAR_EFR ((__force upf_t) (1 << 25))
207 #define UPF_BUG_THRE ((__force upf_t) (1 << 26))
208 /* The exact UART type is known and should not be probed. */
209 #define UPF_FIXED_TYPE ((__force upf_t) (1 << 27))
210 #define UPF_BOOT_AUTOCONF ((__force upf_t) (1 << 28))
211 #define UPF_FIXED_PORT ((__force upf_t) (1 << 29))
212 #define UPF_DEAD ((__force upf_t) (1 << 30))
213 #define UPF_IOREMAP ((__force upf_t) (1 << 31))
214
215 #define __UPF_CHANGE_MASK 0x17fff
216 #define UPF_CHANGE_MASK ((__force upf_t) __UPF_CHANGE_MASK)
217 #define UPF_USR_MASK ((__force upf_t) (UPF_SPD_MASK|UPF_LOW_LATENCY))
218
219 #if __UPF_CHANGE_MASK > ASYNC_FLAGS
220 #error Change mask not equivalent to userspace-visible bit defines
221 #endif
222
223 /*
224 * Must hold termios_rwsem, port mutex and port lock to change;
225 * can hold any one lock to read.
226 */
227 upstat_t status;
228
229 #define UPSTAT_CTS_ENABLE ((__force upstat_t) (1 << 0))
230 #define UPSTAT_DCD_ENABLE ((__force upstat_t) (1 << 1))
231 #define UPSTAT_AUTORTS ((__force upstat_t) (1 << 2))
232 #define UPSTAT_AUTOCTS ((__force upstat_t) (1 << 3))
233 #define UPSTAT_AUTOXOFF ((__force upstat_t) (1 << 4))
234 #define UPSTAT_SYNC_FIFO ((__force upstat_t) (1 << 5))
235
236 int hw_stopped; /* sw-assisted CTS flow state */
237 unsigned int mctrl; /* current modem ctrl settings */
238 unsigned int timeout; /* character-based timeout */
239 unsigned int type; /* port type */
240 const struct uart_ops *ops;
241 unsigned int custom_divisor;
242 unsigned int line; /* port index */
243 unsigned int minor;
244 resource_size_t mapbase; /* for ioremap */
245 resource_size_t mapsize;
246 struct device *dev; /* parent device */
247
248 unsigned long sysrq; /* sysrq timeout */
249 unsigned int sysrq_ch; /* char for sysrq */
250 unsigned char has_sysrq;
251 unsigned char sysrq_seq; /* index in sysrq_toggle_seq */
252
253 unsigned char hub6; /* this should be in the 8250 driver */
254 unsigned char suspended;
255 unsigned char console_reinit;
256 const char *name; /* port name */
257 struct attribute_group *attr_group; /* port specific attributes */
258 const struct attribute_group **tty_groups; /* all attributes (serial core use only) */
259 struct serial_rs485 rs485;
260 struct gpio_desc *rs485_term_gpio; /* enable RS485 bus termination */
261 struct serial_iso7816 iso7816;
262 void *private_data; /* generic platform data pointer */
263
264 ANDROID_KABI_RESERVE(1);
265 ANDROID_KABI_RESERVE(2);
266 };
267
serial_port_in(struct uart_port * up,int offset)268 static inline int serial_port_in(struct uart_port *up, int offset)
269 {
270 return up->serial_in(up, offset);
271 }
272
serial_port_out(struct uart_port * up,int offset,int value)273 static inline void serial_port_out(struct uart_port *up, int offset, int value)
274 {
275 up->serial_out(up, offset, value);
276 }
277
278 /**
279 * enum uart_pm_state - power states for UARTs
280 * @UART_PM_STATE_ON: UART is powered, up and operational
281 * @UART_PM_STATE_OFF: UART is powered off
282 * @UART_PM_STATE_UNDEFINED: sentinel
283 */
284 enum uart_pm_state {
285 UART_PM_STATE_ON = 0,
286 UART_PM_STATE_OFF = 3, /* number taken from ACPI */
287 UART_PM_STATE_UNDEFINED,
288 };
289
290 /*
291 * This is the state information which is persistent across opens.
292 */
293 struct uart_state {
294 struct tty_port port;
295
296 enum uart_pm_state pm_state;
297 struct circ_buf xmit;
298
299 atomic_t refcount;
300 wait_queue_head_t remove_wait;
301 struct uart_port *uart_port;
302 };
303
304 #define UART_XMIT_SIZE PAGE_SIZE
305
306
307 /* number of characters left in xmit buffer before we ask for more */
308 #define WAKEUP_CHARS 256
309
310 /**
311 * uart_xmit_advance - Advance xmit buffer and account Tx'ed chars
312 * @up: uart_port structure describing the port
313 * @chars: number of characters sent
314 *
315 * This function advances the tail of circular xmit buffer by the number of
316 * @chars transmitted and handles accounting of transmitted bytes (into
317 * @up's icount.tx).
318 */
uart_xmit_advance(struct uart_port * up,unsigned int chars)319 static inline void uart_xmit_advance(struct uart_port *up, unsigned int chars)
320 {
321 struct circ_buf *xmit = &up->state->xmit;
322
323 xmit->tail = (xmit->tail + chars) & (UART_XMIT_SIZE - 1);
324 up->icount.tx += chars;
325 }
326
327 struct module;
328 struct tty_driver;
329
330 struct uart_driver {
331 struct module *owner;
332 const char *driver_name;
333 const char *dev_name;
334 int major;
335 int minor;
336 int nr;
337 struct console *cons;
338
339 /*
340 * these are private; the low level driver should not
341 * touch these; they should be initialised to NULL
342 */
343 struct uart_state *state;
344 struct tty_driver *tty_driver;
345
346 ANDROID_KABI_RESERVE(1);
347 };
348
349 void uart_write_wakeup(struct uart_port *port);
350
351 /*
352 * Baud rate helpers.
353 */
354 void uart_update_timeout(struct uart_port *port, unsigned int cflag,
355 unsigned int baud);
356 unsigned int uart_get_baud_rate(struct uart_port *port, struct ktermios *termios,
357 struct ktermios *old, unsigned int min,
358 unsigned int max);
359 unsigned int uart_get_divisor(struct uart_port *port, unsigned int baud);
360
361 /* Base timer interval for polling */
uart_poll_timeout(struct uart_port * port)362 static inline int uart_poll_timeout(struct uart_port *port)
363 {
364 int timeout = port->timeout;
365
366 return timeout > 6 ? (timeout / 2 - 2) : 1;
367 }
368
369 /*
370 * Console helpers.
371 */
372 struct earlycon_device {
373 struct console *con;
374 struct uart_port port;
375 char options[16]; /* e.g., 115200n8 */
376 unsigned int baud;
377 };
378
379 struct earlycon_id {
380 char name[15];
381 char name_term; /* In case compiler didn't '\0' term name */
382 char compatible[128];
383 int (*setup)(struct earlycon_device *, const char *options);
384 };
385
386 extern const struct earlycon_id *__earlycon_table[];
387 extern const struct earlycon_id *__earlycon_table_end[];
388
389 #if defined(CONFIG_SERIAL_EARLYCON) && !defined(MODULE)
390 #define EARLYCON_USED_OR_UNUSED __used
391 #else
392 #define EARLYCON_USED_OR_UNUSED __maybe_unused
393 #endif
394
395 #define _OF_EARLYCON_DECLARE(_name, compat, fn, unique_id) \
396 static const struct earlycon_id unique_id \
397 EARLYCON_USED_OR_UNUSED __initconst \
398 = { .name = __stringify(_name), \
399 .compatible = compat, \
400 .setup = fn }; \
401 static const struct earlycon_id EARLYCON_USED_OR_UNUSED \
402 __section("__earlycon_table") \
403 * const __PASTE(__p, unique_id) = &unique_id
404
405 #define OF_EARLYCON_DECLARE(_name, compat, fn) \
406 _OF_EARLYCON_DECLARE(_name, compat, fn, \
407 __UNIQUE_ID(__earlycon_##_name))
408
409 #define EARLYCON_DECLARE(_name, fn) OF_EARLYCON_DECLARE(_name, "", fn)
410
411 extern int of_setup_earlycon(const struct earlycon_id *match,
412 unsigned long node,
413 const char *options);
414
415 #ifdef CONFIG_SERIAL_EARLYCON
416 extern bool earlycon_acpi_spcr_enable __initdata;
417 int setup_earlycon(char *buf);
418 #else
419 static const bool earlycon_acpi_spcr_enable EARLYCON_USED_OR_UNUSED;
setup_earlycon(char * buf)420 static inline int setup_earlycon(char *buf) { return 0; }
421 #endif
422
uart_console_enabled(struct uart_port * port)423 static inline bool uart_console_enabled(struct uart_port *port)
424 {
425 return uart_console(port) && (port->cons->flags & CON_ENABLED);
426 }
427
428 struct uart_port *uart_get_console(struct uart_port *ports, int nr,
429 struct console *c);
430 int uart_parse_earlycon(char *p, unsigned char *iotype, resource_size_t *addr,
431 char **options);
432 void uart_parse_options(const char *options, int *baud, int *parity, int *bits,
433 int *flow);
434 int uart_set_options(struct uart_port *port, struct console *co, int baud,
435 int parity, int bits, int flow);
436 struct tty_driver *uart_console_device(struct console *co, int *index);
437 void uart_console_write(struct uart_port *port, const char *s,
438 unsigned int count,
439 void (*putchar)(struct uart_port *, int));
440
441 /*
442 * Port/driver registration/removal
443 */
444 int uart_register_driver(struct uart_driver *uart);
445 void uart_unregister_driver(struct uart_driver *uart);
446 int uart_add_one_port(struct uart_driver *reg, struct uart_port *port);
447 int uart_remove_one_port(struct uart_driver *reg, struct uart_port *port);
448 int uart_match_port(struct uart_port *port1, struct uart_port *port2);
449
450 /*
451 * Power Management
452 */
453 int uart_suspend_port(struct uart_driver *reg, struct uart_port *port);
454 int uart_resume_port(struct uart_driver *reg, struct uart_port *port);
455
456 #define uart_circ_empty(circ) ((circ)->head == (circ)->tail)
457 #define uart_circ_clear(circ) ((circ)->head = (circ)->tail = 0)
458
459 #define uart_circ_chars_pending(circ) \
460 (CIRC_CNT((circ)->head, (circ)->tail, UART_XMIT_SIZE))
461
462 #define uart_circ_chars_free(circ) \
463 (CIRC_SPACE((circ)->head, (circ)->tail, UART_XMIT_SIZE))
464
uart_tx_stopped(struct uart_port * port)465 static inline int uart_tx_stopped(struct uart_port *port)
466 {
467 struct tty_struct *tty = port->state->port.tty;
468 if ((tty && tty->stopped) || port->hw_stopped)
469 return 1;
470 return 0;
471 }
472
uart_cts_enabled(struct uart_port * uport)473 static inline bool uart_cts_enabled(struct uart_port *uport)
474 {
475 return !!(uport->status & UPSTAT_CTS_ENABLE);
476 }
477
uart_softcts_mode(struct uart_port * uport)478 static inline bool uart_softcts_mode(struct uart_port *uport)
479 {
480 upstat_t mask = UPSTAT_CTS_ENABLE | UPSTAT_AUTOCTS;
481
482 return ((uport->status & mask) == UPSTAT_CTS_ENABLE);
483 }
484
485 /*
486 * The following are helper functions for the low level drivers.
487 */
488
489 extern void uart_handle_dcd_change(struct uart_port *uport,
490 unsigned int status);
491 extern void uart_handle_cts_change(struct uart_port *uport,
492 unsigned int status);
493
494 extern void uart_insert_char(struct uart_port *port, unsigned int status,
495 unsigned int overrun, unsigned int ch, unsigned int flag);
496
497 void uart_xchar_out(struct uart_port *uport, int offset);
498
499 #ifdef CONFIG_MAGIC_SYSRQ_SERIAL
500 #define SYSRQ_TIMEOUT (HZ * 5)
501
502 bool uart_try_toggle_sysrq(struct uart_port *port, unsigned int ch);
503
uart_handle_sysrq_char(struct uart_port * port,unsigned int ch)504 static inline int uart_handle_sysrq_char(struct uart_port *port, unsigned int ch)
505 {
506 if (!port->sysrq)
507 return 0;
508
509 if (ch && time_before(jiffies, port->sysrq)) {
510 if (sysrq_mask()) {
511 handle_sysrq(ch);
512 port->sysrq = 0;
513 return 1;
514 }
515 if (uart_try_toggle_sysrq(port, ch))
516 return 1;
517 }
518 port->sysrq = 0;
519
520 return 0;
521 }
522
uart_prepare_sysrq_char(struct uart_port * port,unsigned int ch)523 static inline int uart_prepare_sysrq_char(struct uart_port *port, unsigned int ch)
524 {
525 if (!port->sysrq)
526 return 0;
527
528 if (ch && time_before(jiffies, port->sysrq)) {
529 if (sysrq_mask()) {
530 port->sysrq_ch = ch;
531 port->sysrq = 0;
532 return 1;
533 }
534 if (uart_try_toggle_sysrq(port, ch))
535 return 1;
536 }
537 port->sysrq = 0;
538
539 return 0;
540 }
541
uart_unlock_and_check_sysrq(struct uart_port * port,unsigned long irqflags)542 static inline void uart_unlock_and_check_sysrq(struct uart_port *port, unsigned long irqflags)
543 {
544 int sysrq_ch;
545
546 if (!port->has_sysrq) {
547 spin_unlock_irqrestore(&port->lock, irqflags);
548 return;
549 }
550
551 sysrq_ch = port->sysrq_ch;
552 port->sysrq_ch = 0;
553
554 spin_unlock_irqrestore(&port->lock, irqflags);
555
556 if (sysrq_ch)
557 handle_sysrq(sysrq_ch);
558 }
559 #else /* CONFIG_MAGIC_SYSRQ_SERIAL */
uart_handle_sysrq_char(struct uart_port * port,unsigned int ch)560 static inline int uart_handle_sysrq_char(struct uart_port *port, unsigned int ch)
561 {
562 return 0;
563 }
uart_prepare_sysrq_char(struct uart_port * port,unsigned int ch)564 static inline int uart_prepare_sysrq_char(struct uart_port *port, unsigned int ch)
565 {
566 return 0;
567 }
uart_unlock_and_check_sysrq(struct uart_port * port,unsigned long irqflags)568 static inline void uart_unlock_and_check_sysrq(struct uart_port *port, unsigned long irqflags)
569 {
570 spin_unlock_irqrestore(&port->lock, irqflags);
571 }
572 #endif /* CONFIG_MAGIC_SYSRQ_SERIAL */
573
574 /*
575 * We do the SysRQ and SAK checking like this...
576 */
uart_handle_break(struct uart_port * port)577 static inline int uart_handle_break(struct uart_port *port)
578 {
579 struct uart_state *state = port->state;
580
581 if (port->handle_break)
582 port->handle_break(port);
583
584 #ifdef CONFIG_MAGIC_SYSRQ_SERIAL
585 if (port->has_sysrq && uart_console(port)) {
586 if (!port->sysrq) {
587 port->sysrq = jiffies + SYSRQ_TIMEOUT;
588 return 1;
589 }
590 port->sysrq = 0;
591 }
592 #endif
593 if (port->flags & UPF_SAK)
594 do_SAK(state->port.tty);
595 return 0;
596 }
597
598 /*
599 * UART_ENABLE_MS - determine if port should enable modem status irqs
600 */
601 #define UART_ENABLE_MS(port,cflag) ((port)->flags & UPF_HARDPPS_CD || \
602 (cflag) & CRTSCTS || \
603 !((cflag) & CLOCAL))
604
605 int uart_get_rs485_mode(struct uart_port *port);
606 #endif /* LINUX_SERIAL_CORE_H */
607