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 * long (*compat_ioctl)(struct tty_struct * tty, struct file * file, 63 * unsigned int cmd, unsigned long arg); 64 * 65 * Process ioctl calls from 32-bit process on 64-bit system 66 * 67 * void (*set_termios)(struct tty_struct *tty, struct ktermios * old); 68 * 69 * This function notifies the line discpline that a change has 70 * been made to the termios structure. 71 * 72 * int (*poll)(struct tty_struct * tty, struct file * file, 73 * poll_table *wait); 74 * 75 * This function is called when a user attempts to select/poll on a 76 * tty device. It is solely the responsibility of the line 77 * discipline to handle poll requests. 78 * 79 * void (*receive_buf)(struct tty_struct *, const unsigned char *cp, 80 * char *fp, int count); 81 * 82 * This function is called by the low-level tty driver to send 83 * characters received by the hardware to the line discpline for 84 * processing. <cp> is a pointer to the buffer of input 85 * character received by the device. <fp> is a pointer to a 86 * pointer of flag bytes which indicate whether a character was 87 * received with a parity error, etc. 88 * 89 * void (*write_wakeup)(struct tty_struct *); 90 * 91 * This function is called by the low-level tty driver to signal 92 * that line discpline should try to send more characters to the 93 * low-level driver for transmission. If the line discpline does 94 * not have any more data to send, it can just return. 95 * 96 * int (*hangup)(struct tty_struct *) 97 * 98 * Called on a hangup. Tells the discipline that it should 99 * cease I/O to the tty driver. Can sleep. The driver should 100 * seek to perform this action quickly but should wait until 101 * any pending driver I/O is completed. 102 * 103 * void (*dcd_change)(struct tty_struct *tty, unsigned int status) 104 * 105 * Tells the discipline that the DCD pin has changed its status. 106 * Used exclusively by the N_PPS (Pulse-Per-Second) line discipline. 107 */ 108 109 #include <linux/fs.h> 110 #include <linux/wait.h> 111 #include <linux/wait.h> 112 113 struct tty_ldisc_ops { 114 int magic; 115 char *name; 116 int num; 117 int flags; 118 119 /* 120 * The following routines are called from above. 121 */ 122 int (*open)(struct tty_struct *); 123 void (*close)(struct tty_struct *); 124 void (*flush_buffer)(struct tty_struct *tty); 125 ssize_t (*chars_in_buffer)(struct tty_struct *tty); 126 ssize_t (*read)(struct tty_struct * tty, struct file * file, 127 unsigned char __user * buf, size_t nr); 128 ssize_t (*write)(struct tty_struct * tty, struct file * file, 129 const unsigned char * buf, size_t nr); 130 int (*ioctl)(struct tty_struct * tty, struct file * file, 131 unsigned int cmd, unsigned long arg); 132 long (*compat_ioctl)(struct tty_struct * tty, struct file * file, 133 unsigned int cmd, unsigned long arg); 134 void (*set_termios)(struct tty_struct *tty, struct ktermios * old); 135 unsigned int (*poll)(struct tty_struct *, struct file *, 136 struct poll_table_struct *); 137 int (*hangup)(struct tty_struct *tty); 138 139 /* 140 * The following routines are called from below. 141 */ 142 void (*receive_buf)(struct tty_struct *, const unsigned char *cp, 143 char *fp, int count); 144 void (*write_wakeup)(struct tty_struct *); 145 void (*dcd_change)(struct tty_struct *, unsigned int); 146 147 struct module *owner; 148 149 int refcount; 150 }; 151 152 struct tty_ldisc { 153 struct tty_ldisc_ops *ops; 154 atomic_t users; 155 wait_queue_head_t wq_idle; 156 }; 157 158 #define TTY_LDISC_MAGIC 0x5403 159 160 #define LDISC_FLAG_DEFINED 0x00000001 161 162 #define MODULE_ALIAS_LDISC(ldisc) \ 163 MODULE_ALIAS("tty-ldisc-" __stringify(ldisc)) 164 165 #endif /* _LINUX_TTY_LDISC_H */ 166