| /* SPDX-License-Identifier: GPL-2.0 */ |
| #ifndef _LINUX_TTY_LDISC_H |
| #define _LINUX_TTY_LDISC_H |
| |
| struct tty_struct; |
| |
| /* |
| * 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 (*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. |
| * |
| * int (*compat_ioctl)(struct tty_struct * tty, struct file * file, |
| * unsigned int cmd, unsigned long arg); |
| * |
| * Process ioctl calls from 32-bit process on 64-bit system |
| * |
| * NOTE: only ioctls that are neither "pointer to compatible |
| * structure" nor tty-generic. Something private that takes |
| * an integer or a pointer to wordsize-sensitive structure |
| * belongs here, but most of ldiscs will happily leave |
| * it NULL. |
| * |
| * void (*set_termios)(struct tty_struct *tty, struct ktermios * 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. <fp> may be NULL to indicate |
| * all data received is TTY_NORMAL. |
| * |
| * 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. If the line |
| * discipline does have some data to send, please arise a tasklet |
| * or workqueue to do the real data transfer. Do not send data in |
| * this hook, it may leads to a deadlock. |
| * |
| * 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. |
| * |
| * void (*dcd_change)(struct tty_struct *tty, unsigned int status) |
| * |
| * Tells the discipline that the DCD pin has changed its status. |
| * Used exclusively by the N_PPS (Pulse-Per-Second) line discipline. |
| * |
| * int (*receive_buf2)(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. <fp> may be NULL to indicate |
| * all data received is TTY_NORMAL. |
| * If assigned, prefer this function for automatic flow control. |
| */ |
| |
| #include <linux/fs.h> |
| #include <linux/wait.h> |
| #include <linux/atomic.h> |
| #include <linux/list.h> |
| #include <linux/lockdep.h> |
| #include <linux/seq_file.h> |
| |
| /* |
| * the semaphore definition |
| */ |
| struct ld_semaphore { |
| atomic_long_t count; |
| raw_spinlock_t wait_lock; |
| unsigned int wait_readers; |
| struct list_head read_wait; |
| struct list_head write_wait; |
| #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| struct lockdep_map dep_map; |
| #endif |
| }; |
| |
| void __init_ldsem(struct ld_semaphore *sem, const char *name, |
| struct lock_class_key *key); |
| |
| #define init_ldsem(sem) \ |
| do { \ |
| static struct lock_class_key __key; \ |
| \ |
| __init_ldsem((sem), #sem, &__key); \ |
| } while (0) |
| |
| |
| int ldsem_down_read(struct ld_semaphore *sem, long timeout); |
| int ldsem_down_read_trylock(struct ld_semaphore *sem); |
| int ldsem_down_write(struct ld_semaphore *sem, long timeout); |
| int ldsem_down_write_trylock(struct ld_semaphore *sem); |
| void ldsem_up_read(struct ld_semaphore *sem); |
| void ldsem_up_write(struct ld_semaphore *sem); |
| |
| #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| int ldsem_down_read_nested(struct ld_semaphore *sem, int subclass, |
| long timeout); |
| int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass, |
| long timeout); |
| #else |
| # define ldsem_down_read_nested(sem, subclass, timeout) \ |
| ldsem_down_read(sem, timeout) |
| # define ldsem_down_write_nested(sem, subclass, timeout) \ |
| ldsem_down_write(sem, timeout) |
| #endif |
| |
| |
| struct tty_ldisc_ops { |
| char *name; |
| int num; |
| |
| /* |
| * 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 (*read)(struct tty_struct *tty, struct file *file, |
| unsigned char *buf, size_t nr, |
| void **cookie, unsigned long offset); |
| 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); |
| int (*compat_ioctl)(struct tty_struct *tty, struct file *file, |
| unsigned int cmd, unsigned long arg); |
| void (*set_termios)(struct tty_struct *tty, struct ktermios *old); |
| __poll_t (*poll)(struct tty_struct *, struct file *, |
| struct poll_table_struct *); |
| void (*hangup)(struct tty_struct *tty); |
| |
| /* |
| * The following routines are called from below. |
| */ |
| void (*receive_buf)(struct tty_struct *, const unsigned char *cp, |
| const char *fp, int count); |
| void (*write_wakeup)(struct tty_struct *); |
| void (*dcd_change)(struct tty_struct *, unsigned int); |
| int (*receive_buf2)(struct tty_struct *, const unsigned char *cp, |
| const char *fp, int count); |
| |
| struct module *owner; |
| }; |
| |
| struct tty_ldisc { |
| struct tty_ldisc_ops *ops; |
| struct tty_struct *tty; |
| }; |
| |
| #define MODULE_ALIAS_LDISC(ldisc) \ |
| MODULE_ALIAS("tty-ldisc-" __stringify(ldisc)) |
| |
| extern const struct seq_operations tty_ldiscs_seq_ops; |
| |
| struct tty_ldisc *tty_ldisc_ref(struct tty_struct *); |
| void tty_ldisc_deref(struct tty_ldisc *); |
| struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *); |
| |
| void tty_ldisc_flush(struct tty_struct *tty); |
| |
| int tty_register_ldisc(struct tty_ldisc_ops *new_ldisc); |
| void tty_unregister_ldisc(struct tty_ldisc_ops *ldisc); |
| int tty_set_ldisc(struct tty_struct *tty, int disc); |
| |
| #endif /* _LINUX_TTY_LDISC_H */ |