tty_ldisc.h 5.2 KB

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  1. #ifndef _LINUX_TTY_LDISC_H
  2. #define _LINUX_TTY_LDISC_H
  3. /*
  4. * This structure defines the interface between the tty line discipline
  5. * implementation and the tty routines. The following routines can be
  6. * defined; unless noted otherwise, they are optional, and can be
  7. * filled in with a null pointer.
  8. *
  9. * int (*open)(struct tty_struct *);
  10. *
  11. * This function is called when the line discipline is associated
  12. * with the tty. The line discipline can use this as an
  13. * opportunity to initialize any state needed by the ldisc routines.
  14. *
  15. * void (*close)(struct tty_struct *);
  16. *
  17. * This function is called when the line discipline is being
  18. * shutdown, either because the tty is being closed or because
  19. * the tty is being changed to use a new line discipline
  20. *
  21. * void (*flush_buffer)(struct tty_struct *tty);
  22. *
  23. * This function instructs the line discipline to clear its
  24. * buffers of any input characters it may have queued to be
  25. * delivered to the user mode process.
  26. *
  27. * ssize_t (*chars_in_buffer)(struct tty_struct *tty);
  28. *
  29. * This function returns the number of input characters the line
  30. * discipline may have queued up to be delivered to the user mode
  31. * process.
  32. *
  33. * ssize_t (*read)(struct tty_struct * tty, struct file * file,
  34. * unsigned char * buf, size_t nr);
  35. *
  36. * This function is called when the user requests to read from
  37. * the tty. The line discipline will return whatever characters
  38. * it has buffered up for the user. If this function is not
  39. * defined, the user will receive an EIO error.
  40. *
  41. * ssize_t (*write)(struct tty_struct * tty, struct file * file,
  42. * const unsigned char * buf, size_t nr);
  43. *
  44. * This function is called when the user requests to write to the
  45. * tty. The line discipline will deliver the characters to the
  46. * low-level tty device for transmission, optionally performing
  47. * some processing on the characters first. If this function is
  48. * not defined, the user will receive an EIO error.
  49. *
  50. * int (*ioctl)(struct tty_struct * tty, struct file * file,
  51. * unsigned int cmd, unsigned long arg);
  52. *
  53. * This function is called when the user requests an ioctl which
  54. * is not handled by the tty layer or the low-level tty driver.
  55. * It is intended for ioctls which affect line discpline
  56. * operation. Note that the search order for ioctls is (1) tty
  57. * layer, (2) tty low-level driver, (3) line discpline. So a
  58. * low-level driver can "grab" an ioctl request before the line
  59. * discpline has a chance to see it.
  60. *
  61. * void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
  62. *
  63. * This function notifies the line discpline that a change has
  64. * been made to the termios structure.
  65. *
  66. * int (*poll)(struct tty_struct * tty, struct file * file,
  67. * poll_table *wait);
  68. *
  69. * This function is called when a user attempts to select/poll on a
  70. * tty device. It is solely the responsibility of the line
  71. * discipline to handle poll requests.
  72. *
  73. * void (*receive_buf)(struct tty_struct *, const unsigned char *cp,
  74. * char *fp, int count);
  75. *
  76. * This function is called by the low-level tty driver to send
  77. * characters received by the hardware to the line discpline for
  78. * processing. <cp> is a pointer to the buffer of input
  79. * character received by the device. <fp> is a pointer to a
  80. * pointer of flag bytes which indicate whether a character was
  81. * received with a parity error, etc.
  82. *
  83. * void (*write_wakeup)(struct tty_struct *);
  84. *
  85. * This function is called by the low-level tty driver to signal
  86. * that line discpline should try to send more characters to the
  87. * low-level driver for transmission. If the line discpline does
  88. * not have any more data to send, it can just return.
  89. *
  90. * int (*hangup)(struct tty_struct *)
  91. *
  92. * Called on a hangup. Tells the discipline that it should
  93. * cease I/O to the tty driver. Can sleep. The driver should
  94. * seek to perform this action quickly but should wait until
  95. * any pending driver I/O is completed.
  96. */
  97. #include <linux/fs.h>
  98. #include <linux/wait.h>
  99. struct tty_ldisc {
  100. int magic;
  101. char *name;
  102. int num;
  103. int flags;
  104. /*
  105. * The following routines are called from above.
  106. */
  107. int (*open)(struct tty_struct *);
  108. void (*close)(struct tty_struct *);
  109. void (*flush_buffer)(struct tty_struct *tty);
  110. ssize_t (*chars_in_buffer)(struct tty_struct *tty);
  111. ssize_t (*read)(struct tty_struct * tty, struct file * file,
  112. unsigned char __user * buf, size_t nr);
  113. ssize_t (*write)(struct tty_struct * tty, struct file * file,
  114. const unsigned char * buf, size_t nr);
  115. int (*ioctl)(struct tty_struct * tty, struct file * file,
  116. unsigned int cmd, unsigned long arg);
  117. void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
  118. unsigned int (*poll)(struct tty_struct *, struct file *,
  119. struct poll_table_struct *);
  120. int (*hangup)(struct tty_struct *tty);
  121. /*
  122. * The following routines are called from below.
  123. */
  124. void (*receive_buf)(struct tty_struct *, const unsigned char *cp,
  125. char *fp, int count);
  126. void (*write_wakeup)(struct tty_struct *);
  127. struct module *owner;
  128. int refcount;
  129. };
  130. #define TTY_LDISC_MAGIC 0x5403
  131. #define LDISC_FLAG_DEFINED 0x00000001
  132. #define MODULE_ALIAS_LDISC(ldisc) \
  133. MODULE_ALIAS("tty-ldisc-" __stringify(ldisc))
  134. #endif /* _LINUX_TTY_LDISC_H */