#ifndef _LINUX_TTY_LDISC_H #define _LINUX_TTY_LDISC_H /* * This structure defines the interface between the tty line discipline * implementation and the tty routines. The following routines can be * defined; unless noted otherwise, they are optional, and can be * filled in with a null pointer. * * int (*open)(struct tty_struct *); * * This function is called when the line discipline is associated * with the tty. The line discipline can use this as an * opportunity to initialize any state needed by the ldisc routines. * * void (*close)(struct tty_struct *); * * This function is called when the line discipline is being * shutdown, either because the tty is being closed or because * the tty is being changed to use a new line discipline * * void (*flush_buffer)(struct tty_struct *tty); * * This function instructs the line discipline to clear its * buffers of any input characters it may have queued to be * delivered to the user mode process. * * ssize_t (*chars_in_buffer)(struct tty_struct *tty); * * This function returns the number of input characters the line * discipline may have queued up to be delivered to the user mode * process. * * ssize_t (*read)(struct tty_struct * tty, struct file * file, * unsigned char * buf, size_t nr); * * This function is called when the user requests to read from * the tty. The line discipline will return whatever characters * it has buffered up for the user. If this function is not * defined, the user will receive an EIO error. * * ssize_t (*write)(struct tty_struct * tty, struct file * file, * const unsigned char * buf, size_t nr); * * This function is called when the user requests to write to the * tty. The line discipline will deliver the characters to the * low-level tty device for transmission, optionally performing * some processing on the characters first. If this function is * not defined, the user will receive an EIO error. * * int (*ioctl)(struct tty_struct * tty, struct file * file, * unsigned int cmd, unsigned long arg); * * This function is called when the user requests an ioctl which * is not handled by the tty layer or the low-level tty driver. * It is intended for ioctls which affect line discpline * operation. Note that the search order for ioctls is (1) tty * layer, (2) tty low-level driver, (3) line discpline. So a * low-level driver can "grab" an ioctl request before the line * discpline has a chance to see it. * * void (*set_termios)(struct tty_struct *tty, struct termios * old); * * This function notifies the line discpline that a change has * been made to the termios structure. * * int (*poll)(struct tty_struct * tty, struct file * file, * poll_table *wait); * * This function is called when a user attempts to select/poll on a * tty device. It is solely the responsibility of the line * discipline to handle poll requests. * * void (*receive_buf)(struct tty_struct *, const unsigned char *cp, * char *fp, int count); * * This function is called by the low-level tty driver to send * characters received by the hardware to the line discpline for * processing. <cp> is a pointer to the buffer of input * character received by the device. <fp> is a pointer to a * pointer of flag bytes which indicate whether a character was * received with a parity error, etc. * * int (*receive_room)(struct tty_struct *); * * This function is called by the low-level tty driver to * determine how many characters the line discpline can accept. * The low-level driver must not send more characters than was * indicated by receive_room, or the line discpline may drop * those characters. * * void (*write_wakeup)(struct tty_struct *); * * This function is called by the low-level tty driver to signal * that line discpline should try to send more characters to the * low-level driver for transmission. If the line discpline does * not have any more data to send, it can just return. * * int (*hangup)(struct tty_struct *) * * Called on a hangup. Tells the discipline that it should * cease I/O to the tty driver. Can sleep. The driver should * seek to perform this action quickly but should wait until * any pending driver I/O is completed. */ #include <linux/fs.h> #include <linux/wait.h> struct tty_ldisc { int magic; char *name; int num; int flags; /* * The following routines are called from above. */ int (*open)(struct tty_struct *); void (*close)(struct tty_struct *); void (*flush_buffer)(struct tty_struct *tty); ssize_t (*chars_in_buffer)(struct tty_struct *tty); ssize_t (*read)(struct tty_struct * tty, struct file * file, unsigned char __user * buf, size_t nr); ssize_t (*write)(struct tty_struct * tty, struct file * file, const unsigned char * buf, size_t nr); int (*ioctl)(struct tty_struct * tty, struct file * file, unsigned int cmd, unsigned long arg); void (*set_termios)(struct tty_struct *tty, struct termios * old); unsigned int (*poll)(struct tty_struct *, struct file *, struct poll_table_struct *); int (*hangup)(struct tty_struct *tty); /* * The following routines are called from below. */ void (*receive_buf)(struct tty_struct *, const unsigned char *cp, char *fp, int count); int (*receive_room)(struct tty_struct *); void (*write_wakeup)(struct tty_struct *); struct module *owner; int refcount; }; #define TTY_LDISC_MAGIC 0x5403 #define LDISC_FLAG_DEFINED 0x00000001 #define MODULE_ALIAS_LDISC(ldisc) \ MODULE_ALIAS("tty-ldisc-" __stringify(ldisc)) #endif /* _LINUX_TTY_LDISC_H */