include/linux/serial_core.h

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