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            (*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
  89struct 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
 103typedef unsigned int __bitwise upf_t;
 104typedef unsigned int __bitwise upstat_t;
 105
 106struct 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        unsigned char           console_reinit;
 252        const char              *name;                  /* port name */
 253        struct attribute_group  *attr_group;            /* port specific attributes */
 254        const struct attribute_group **tty_groups;      /* all attributes (serial core use only) */
 255        struct serial_rs485     rs485;
 256        struct gpio_desc        *rs485_term_gpio;       /* enable RS485 bus termination */
 257        struct serial_iso7816   iso7816;
 258        void                    *private_data;          /* generic platform data pointer */
 259};
 260
 261static inline int serial_port_in(struct uart_port *up, int offset)
 262{
 263        return up->serial_in(up, offset);
 264}
 265
 266static inline void serial_port_out(struct uart_port *up, int offset, int value)
 267{
 268        up->serial_out(up, offset, value);
 269}
 270
 271/**
 272 * enum uart_pm_state - power states for UARTs
 273 * @UART_PM_STATE_ON: UART is powered, up and operational
 274 * @UART_PM_STATE_OFF: UART is powered off
 275 * @UART_PM_STATE_UNDEFINED: sentinel
 276 */
 277enum uart_pm_state {
 278        UART_PM_STATE_ON = 0,
 279        UART_PM_STATE_OFF = 3, /* number taken from ACPI */
 280        UART_PM_STATE_UNDEFINED,
 281};
 282
 283/*
 284 * This is the state information which is persistent across opens.
 285 */
 286struct uart_state {
 287        struct tty_port         port;
 288
 289        enum uart_pm_state      pm_state;
 290        struct circ_buf         xmit;
 291
 292        atomic_t                refcount;
 293        wait_queue_head_t       remove_wait;
 294        struct uart_port        *uart_port;
 295};
 296
 297#define UART_XMIT_SIZE  PAGE_SIZE
 298
 299
 300/* number of characters left in xmit buffer before we ask for more */
 301#define WAKEUP_CHARS            256
 302
 303struct module;
 304struct tty_driver;
 305
 306struct uart_driver {
 307        struct module           *owner;
 308        const char              *driver_name;
 309        const char              *dev_name;
 310        int                      major;
 311        int                      minor;
 312        int                      nr;
 313        struct console          *cons;
 314
 315        /*
 316         * these are private; the low level driver should not
 317         * touch these; they should be initialised to NULL
 318         */
 319        struct uart_state       *state;
 320        struct tty_driver       *tty_driver;
 321};
 322
 323void uart_write_wakeup(struct uart_port *port);
 324
 325/*
 326 * Baud rate helpers.
 327 */
 328void uart_update_timeout(struct uart_port *port, unsigned int cflag,
 329                         unsigned int baud);
 330unsigned int uart_get_baud_rate(struct uart_port *port, struct ktermios *termios,
 331                                struct ktermios *old, unsigned int min,
 332                                unsigned int max);
 333unsigned int uart_get_divisor(struct uart_port *port, unsigned int baud);
 334
 335/* Base timer interval for polling */
 336static inline int uart_poll_timeout(struct uart_port *port)
 337{
 338        int timeout = port->timeout;
 339
 340        return timeout > 6 ? (timeout / 2 - 2) : 1;
 341}
 342
 343/*
 344 * Console helpers.
 345 */
 346struct earlycon_device {
 347        struct console *con;
 348        struct uart_port port;
 349        char options[16];               /* e.g., 115200n8 */
 350        unsigned int baud;
 351};
 352
 353struct earlycon_id {
 354        char    name[15];
 355        char    name_term;      /* In case compiler didn't '\0' term name */
 356        char    compatible[128];
 357        int     (*setup)(struct earlycon_device *, const char *options);
 358};
 359
 360extern const struct earlycon_id *__earlycon_table[];
 361extern const struct earlycon_id *__earlycon_table_end[];
 362
 363#if defined(CONFIG_SERIAL_EARLYCON) && !defined(MODULE)
 364#define EARLYCON_USED_OR_UNUSED __used
 365#else
 366#define EARLYCON_USED_OR_UNUSED __maybe_unused
 367#endif
 368
 369#define _OF_EARLYCON_DECLARE(_name, compat, fn, unique_id)              \
 370        static const struct earlycon_id unique_id                       \
 371             EARLYCON_USED_OR_UNUSED __initconst                        \
 372                = { .name = __stringify(_name),                         \
 373                    .compatible = compat,                               \
 374                    .setup = fn  };                                     \
 375        static const struct earlycon_id EARLYCON_USED_OR_UNUSED         \
 376                __section(__earlycon_table)                             \
 377                * const __PASTE(__p, unique_id) = &unique_id
 378
 379#define OF_EARLYCON_DECLARE(_name, compat, fn)                          \
 380        _OF_EARLYCON_DECLARE(_name, compat, fn,                         \
 381                             __UNIQUE_ID(__earlycon_##_name))
 382
 383#define EARLYCON_DECLARE(_name, fn)     OF_EARLYCON_DECLARE(_name, "", fn)
 384
 385extern int of_setup_earlycon(const struct earlycon_id *match,
 386                             unsigned long node,
 387                             const char *options);
 388
 389#ifdef CONFIG_SERIAL_EARLYCON
 390extern bool earlycon_acpi_spcr_enable __initdata;
 391int setup_earlycon(char *buf);
 392#else
 393static const bool earlycon_acpi_spcr_enable EARLYCON_USED_OR_UNUSED;
 394static inline int setup_earlycon(char *buf) { return 0; }
 395#endif
 396
 397struct uart_port *uart_get_console(struct uart_port *ports, int nr,
 398                                   struct console *c);
 399int uart_parse_earlycon(char *p, unsigned char *iotype, resource_size_t *addr,
 400                        char **options);
 401void uart_parse_options(const char *options, int *baud, int *parity, int *bits,
 402                        int *flow);
 403int uart_set_options(struct uart_port *port, struct console *co, int baud,
 404                     int parity, int bits, int flow);
 405struct tty_driver *uart_console_device(struct console *co, int *index);
 406void uart_console_write(struct uart_port *port, const char *s,
 407                        unsigned int count,
 408                        void (*putchar)(struct uart_port *, int));
 409
 410/*
 411 * Port/driver registration/removal
 412 */
 413int uart_register_driver(struct uart_driver *uart);
 414void uart_unregister_driver(struct uart_driver *uart);
 415int uart_add_one_port(struct uart_driver *reg, struct uart_port *port);
 416int uart_remove_one_port(struct uart_driver *reg, struct uart_port *port);
 417int uart_match_port(struct uart_port *port1, struct uart_port *port2);
 418
 419/*
 420 * Power Management
 421 */
 422int uart_suspend_port(struct uart_driver *reg, struct uart_port *port);
 423int uart_resume_port(struct uart_driver *reg, struct uart_port *port);
 424
 425#define uart_circ_empty(circ)           ((circ)->head == (circ)->tail)
 426#define uart_circ_clear(circ)           ((circ)->head = (circ)->tail = 0)
 427
 428#define uart_circ_chars_pending(circ)   \
 429        (CIRC_CNT((circ)->head, (circ)->tail, UART_XMIT_SIZE))
 430
 431#define uart_circ_chars_free(circ)      \
 432        (CIRC_SPACE((circ)->head, (circ)->tail, UART_XMIT_SIZE))
 433
 434static inline int uart_tx_stopped(struct uart_port *port)
 435{
 436        struct tty_struct *tty = port->state->port.tty;
 437        if ((tty && tty->stopped) || port->hw_stopped)
 438                return 1;
 439        return 0;
 440}
 441
 442static inline bool uart_cts_enabled(struct uart_port *uport)
 443{
 444        return !!(uport->status & UPSTAT_CTS_ENABLE);
 445}
 446
 447static inline bool uart_softcts_mode(struct uart_port *uport)
 448{
 449        upstat_t mask = UPSTAT_CTS_ENABLE | UPSTAT_AUTOCTS;
 450
 451        return ((uport->status & mask) == UPSTAT_CTS_ENABLE);
 452}
 453
 454/*
 455 * The following are helper functions for the low level drivers.
 456 */
 457
 458extern void uart_handle_dcd_change(struct uart_port *uport,
 459                unsigned int status);
 460extern void uart_handle_cts_change(struct uart_port *uport,
 461                unsigned int status);
 462
 463extern void uart_insert_char(struct uart_port *port, unsigned int status,
 464                 unsigned int overrun, unsigned int ch, unsigned int flag);
 465
 466#ifdef CONFIG_MAGIC_SYSRQ_SERIAL
 467#define SYSRQ_TIMEOUT   (HZ * 5)
 468
 469bool uart_try_toggle_sysrq(struct uart_port *port, unsigned int ch);
 470
 471static inline int uart_handle_sysrq_char(struct uart_port *port, unsigned int ch)
 472{
 473        if (!port->sysrq)
 474                return 0;
 475
 476        if (ch && time_before(jiffies, port->sysrq)) {
 477                if (sysrq_mask()) {
 478                        handle_sysrq(ch);
 479                        port->sysrq = 0;
 480                        return 1;
 481                }
 482                if (uart_try_toggle_sysrq(port, ch))
 483                        return 1;
 484        }
 485        port->sysrq = 0;
 486
 487        return 0;
 488}
 489
 490static inline int uart_prepare_sysrq_char(struct uart_port *port, unsigned int ch)
 491{
 492        if (!port->sysrq)
 493                return 0;
 494
 495        if (ch && time_before(jiffies, port->sysrq)) {
 496                if (sysrq_mask()) {
 497                        port->sysrq_ch = ch;
 498                        port->sysrq = 0;
 499                        return 1;
 500                }
 501                if (uart_try_toggle_sysrq(port, ch))
 502                        return 1;
 503        }
 504        port->sysrq = 0;
 505
 506        return 0;
 507}
 508
 509static inline void uart_unlock_and_check_sysrq(struct uart_port *port, unsigned long irqflags)
 510{
 511        int sysrq_ch;
 512
 513        if (!port->has_sysrq) {
 514                spin_unlock_irqrestore(&port->lock, irqflags);
 515                return;
 516        }
 517
 518        sysrq_ch = port->sysrq_ch;
 519        port->sysrq_ch = 0;
 520
 521        spin_unlock_irqrestore(&port->lock, irqflags);
 522
 523        if (sysrq_ch)
 524                handle_sysrq(sysrq_ch);
 525}
 526#else   /* CONFIG_MAGIC_SYSRQ_SERIAL */
 527static inline int uart_handle_sysrq_char(struct uart_port *port, unsigned int ch)
 528{
 529        return 0;
 530}
 531static inline int uart_prepare_sysrq_char(struct uart_port *port, unsigned int ch)
 532{
 533        return 0;
 534}
 535static inline void uart_unlock_and_check_sysrq(struct uart_port *port, unsigned long irqflags)
 536{
 537        spin_unlock_irqrestore(&port->lock, irqflags);
 538}
 539#endif  /* CONFIG_MAGIC_SYSRQ_SERIAL */
 540
 541/*
 542 * We do the SysRQ and SAK checking like this...
 543 */
 544static inline int uart_handle_break(struct uart_port *port)
 545{
 546        struct uart_state *state = port->state;
 547
 548        if (port->handle_break)
 549                port->handle_break(port);
 550
 551#ifdef CONFIG_MAGIC_SYSRQ_SERIAL
 552        if (port->has_sysrq && uart_console(port)) {
 553                if (!port->sysrq) {
 554                        port->sysrq = jiffies + SYSRQ_TIMEOUT;
 555                        return 1;
 556                }
 557                port->sysrq = 0;
 558        }
 559#endif
 560        if (port->flags & UPF_SAK)
 561                do_SAK(state->port.tty);
 562        return 0;
 563}
 564
 565/*
 566 *      UART_ENABLE_MS - determine if port should enable modem status irqs
 567 */
 568#define UART_ENABLE_MS(port,cflag)      ((port)->flags & UPF_HARDPPS_CD || \
 569                                         (cflag) & CRTSCTS || \
 570                                         !((cflag) & CLOCAL))
 571
 572int uart_get_rs485_mode(struct uart_port *port);
 573#endif /* LINUX_SERIAL_CORE_H */
 574