LXR linux/include/linux/serial

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