1 #ifndef _LINUX_TTY_LDISC_H 2 #define _LINUX_TTY_LDISC_H 3 4 /* 5 * This structure defines the interface between the tty line discipline 6 * implementation and the tty routines. The following routines can be 7 * defined; unless noted otherwise, they are optional, and can be 8 * filled in with a null pointer. 9 * 10 * int (*open)(struct tty_struct *); 11 * 12 * This function is called when the line discipline is associated 13 * with the tty. The line discipline can use this as an 14 * opportunity to initialize any state needed by the ldisc routines. 15 * 16 * void (*close)(struct tty_struct *); 17 * 18 * This function is called when the line discipline is being 19 * shutdown, either because the tty is being closed or because 20 * the tty is being changed to use a new line discipline 21 * 22 * void (*flush_buffer)(struct tty_struct *tty); 23 * 24 * This function instructs the line discipline to clear its 25 * buffers of any input characters it may have queued to be 26 * delivered to the user mode process. 27 * 28 * ssize_t (*chars_in_buffer)(struct tty_struct *tty); 29 * 30 * This function returns the number of input characters the line 31 * discipline may have queued up to be delivered to the user mode 32 * process. 33 * 34 * ssize_t (*read)(struct tty_struct * tty, struct file * file, 35 * unsigned char * buf, size_t nr); 36 * 37 * This function is called when the user requests to read from 38 * the tty. The line discipline will return whatever characters 39 * it has buffered up for the user. If this function is not 40 * defined, the user will receive an EIO error. 41 * 42 * ssize_t (*write)(struct tty_struct * tty, struct file * file, 43 * const unsigned char * buf, size_t nr); 44 * 45 * This function is called when the user requests to write to the 46 * tty. The line discipline will deliver the characters to the 47 * low-level tty device for transmission, optionally performing 48 * some processing on the characters first. If this function is 49 * not defined, the user will receive an EIO error. 50 * 51 * int (*ioctl)(struct tty_struct * tty, struct file * file, 52 * unsigned int cmd, unsigned long arg); 53 * 54 * This function is called when the user requests an ioctl which 55 * is not handled by the tty layer or the low-level tty driver. 56 * It is intended for ioctls which affect line discpline 57 * operation. Note that the search order for ioctls is (1) tty 58 * layer, (2) tty low-level driver, (3) line discpline. So a 59 * low-level driver can "grab" an ioctl request before the line 60 * discpline has a chance to see it. 61 * 62 * void (*set_termios)(struct tty_struct *tty, struct ktermios * old); 63 * 64 * This function notifies the line discpline that a change has 65 * been made to the termios structure. 66 * 67 * int (*poll)(struct tty_struct * tty, struct file * file, 68 * poll_table *wait); 69 * 70 * This function is called when a user attempts to select/poll on a 71 * tty device. It is solely the responsibility of the line 72 * discipline to handle poll requests. 73 * 74 * void (*receive_buf)(struct tty_struct *, const unsigned char *cp, 75 * char *fp, int count); 76 * 77 * This function is called by the low-level tty driver to send 78 * characters received by the hardware to the line discpline for 79 * processing. <cp> is a pointer to the buffer of input 80 * character received by the device. <fp> is a pointer to a 81 * pointer of flag bytes which indicate whether a character was 82 * received with a parity error, etc. 83 * 84 * void (*write_wakeup)(struct tty_struct *); 85 * 86 * This function is called by the low-level tty driver to signal 87 * that line discpline should try to send more characters to the 88 * low-level driver for transmission. If the line discpline does 89 * not have any more data to send, it can just return. 90 * 91 * int (*hangup)(struct tty_struct *) 92 * 93 * Called on a hangup. Tells the discipline that it should 94 * cease I/O to the tty driver. Can sleep. The driver should 95 * seek to perform this action quickly but should wait until 96 * any pending driver I/O is completed. 97 */ 98 99 #include <linux/fs.h> 100 #include <linux/wait.h> 101 102 struct tty_ldisc { 103 int magic; 104 char *name; 105 int num; 106 int flags; 107 108 /* 109 * The following routines are called from above. 110 */ 111 int (*open)(struct tty_struct *); 112 void (*close)(struct tty_struct *); 113 void (*flush_buffer)(struct tty_struct *tty); 114 ssize_t (*chars_in_buffer)(struct tty_struct *tty); 115 ssize_t (*read)(struct tty_struct * tty, struct file * file, 116 unsigned char __user * buf, size_t nr); 117 ssize_t (*write)(struct tty_struct * tty, struct file * file, 118 const unsigned char * buf, size_t nr); 119 int (*ioctl)(struct tty_struct * tty, struct file * file, 120 unsigned int cmd, unsigned long arg); 121 void (*set_termios)(struct tty_struct *tty, struct ktermios * old); 122 unsigned int (*poll)(struct tty_struct *, struct file *, 123 struct poll_table_struct *); 124 int (*hangup)(struct tty_struct *tty); 125 126 /* 127 * The following routines are called from below. 128 */ 129 void (*receive_buf)(struct tty_struct *, const unsigned char *cp, 130 char *fp, int count); 131 void (*write_wakeup)(struct tty_struct *); 132 133 struct module *owner; 134 135 int refcount; 136 }; 137 138 #define TTY_LDISC_MAGIC 0x5403 139 140 #define LDISC_FLAG_DEFINED 0x00000001 141 142 #define MODULE_ALIAS_LDISC(ldisc) \ 143 MODULE_ALIAS("tty-ldisc-" __stringify(ldisc)) 144 145 #endif /* _LINUX_TTY_LDISC_H */ 146