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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /include/linux/tty_driver.h | |
parent | Initial commit. (diff) | |
download | linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip |
Adding upstream version 6.1.76.upstream/6.1.76upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'include/linux/tty_driver.h')
-rw-r--r-- | include/linux/tty_driver.h | 586 |
1 files changed, 586 insertions, 0 deletions
diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h new file mode 100644 index 000000000..e00034118 --- /dev/null +++ b/include/linux/tty_driver.h @@ -0,0 +1,586 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_TTY_DRIVER_H +#define _LINUX_TTY_DRIVER_H + +#include <linux/export.h> +#include <linux/fs.h> +#include <linux/kref.h> +#include <linux/list.h> +#include <linux/cdev.h> +#include <linux/uaccess.h> +#include <linux/termios.h> +#include <linux/seq_file.h> + +struct tty_struct; +struct tty_driver; +struct serial_icounter_struct; +struct serial_struct; + +/** + * struct tty_operations -- interface between driver and tty + * + * @lookup: ``struct tty_struct *()(struct tty_driver *self, struct file *, + * int idx)`` + * + * Return the tty device corresponding to @idx, %NULL if there is not + * one currently in use and an %ERR_PTR value on error. Called under + * %tty_mutex (for now!) + * + * Optional method. Default behaviour is to use the @self->ttys array. + * + * @install: ``int ()(struct tty_driver *self, struct tty_struct *tty)`` + * + * Install a new @tty into the @self's internal tables. Used in + * conjunction with @lookup and @remove methods. + * + * Optional method. Default behaviour is to use the @self->ttys array. + * + * @remove: ``void ()(struct tty_driver *self, struct tty_struct *tty)`` + * + * Remove a closed @tty from the @self's internal tables. Used in + * conjunction with @lookup and @remove methods. + * + * Optional method. Default behaviour is to use the @self->ttys array. + * + * @open: ``int ()(struct tty_struct *tty, struct file *)`` + * + * This routine is called when a particular @tty device is opened. This + * routine is mandatory; if this routine is not filled in, the attempted + * open will fail with %ENODEV. + * + * Required method. Called with tty lock held. May sleep. + * + * @close: ``void ()(struct tty_struct *tty, struct file *)`` + * + * This routine is called when a particular @tty device is closed. At the + * point of return from this call the driver must make no further ldisc + * calls of any kind. + * + * Remark: called even if the corresponding @open() failed. + * + * Required method. Called with tty lock held. May sleep. + * + * @shutdown: ``void ()(struct tty_struct *tty)`` + * + * This routine is called under the tty lock when a particular @tty device + * is closed for the last time. It executes before the @tty resources + * are freed so may execute while another function holds a @tty kref. + * + * @cleanup: ``void ()(struct tty_struct *tty)`` + * + * This routine is called asynchronously when a particular @tty device + * is closed for the last time freeing up the resources. This is + * actually the second part of shutdown for routines that might sleep. + * + * @write: ``int ()(struct tty_struct *tty, const unsigned char *buf, + * int count)`` + * + * This routine is called by the kernel to write a series (@count) of + * characters (@buf) to the @tty device. The characters may come from + * user space or kernel space. This routine will return the + * number of characters actually accepted for writing. + * + * May occur in parallel in special cases. Because this includes panic + * paths drivers generally shouldn't try and do clever locking here. + * + * Optional: Required for writable devices. May not sleep. + * + * @put_char: ``int ()(struct tty_struct *tty, unsigned char ch)`` + * + * This routine is called by the kernel to write a single character @ch to + * the @tty device. If the kernel uses this routine, it must call the + * @flush_chars() routine (if defined) when it is done stuffing characters + * into the driver. If there is no room in the queue, the character is + * ignored. + * + * Optional: Kernel will use the @write method if not provided. Do not + * call this function directly, call tty_put_char(). + * + * @flush_chars: ``void ()(struct tty_struct *tty)`` + * + * This routine is called by the kernel after it has written a + * series of characters to the tty device using @put_char(). + * + * Optional. Do not call this function directly, call + * tty_driver_flush_chars(). + * + * @write_room: ``unsigned int ()(struct tty_struct *tty)`` + * + * This routine returns the numbers of characters the @tty driver + * will accept for queuing to be written. This number is subject + * to change as output buffers get emptied, or if the output flow + * control is acted. + * + * The ldisc is responsible for being intelligent about multi-threading of + * write_room/write calls + * + * Required if @write method is provided else not needed. Do not call this + * function directly, call tty_write_room() + * + * @chars_in_buffer: ``unsigned int ()(struct tty_struct *tty)`` + * + * This routine returns the number of characters in the device private + * output queue. Used in tty_wait_until_sent() and for poll() + * implementation. + * + * Optional: if not provided, it is assumed there is no queue on the + * device. Do not call this function directly, call tty_chars_in_buffer(). + * + * @ioctl: ``int ()(struct tty_struct *tty, unsigned int cmd, + * unsigned long arg)`` + * + * This routine allows the @tty driver to implement device-specific + * ioctls. If the ioctl number passed in @cmd is not recognized by the + * driver, it should return %ENOIOCTLCMD. + * + * Optional. + * + * @compat_ioctl: ``long ()(struct tty_struct *tty, unsigned int cmd, + * unsigned long arg)`` + * + * Implement ioctl processing for 32 bit process on 64 bit system. + * + * Optional. + * + * @set_termios: ``void ()(struct tty_struct *tty, const struct ktermios *old)`` + * + * This routine allows the @tty driver to be notified when device's + * termios settings have changed. New settings are in @tty->termios. + * Previous settings are passed in the @old argument. + * + * The API is defined such that the driver should return the actual modes + * selected. This means that the driver is responsible for modifying any + * bits in @tty->termios it cannot fulfill to indicate the actual modes + * being used. + * + * Optional. Called under the @tty->termios_rwsem. May sleep. + * + * @set_ldisc: ``void ()(struct tty_struct *tty)`` + * + * This routine allows the @tty driver to be notified when the device's + * line discipline is being changed. At the point this is done the + * discipline is not yet usable. + * + * Optional. Called under the @tty->ldisc_sem and @tty->termios_rwsem. + * + * @throttle: ``void ()(struct tty_struct *tty)`` + * + * This routine notifies the @tty driver that input buffers for the line + * discipline are close to full, and it should somehow signal that no more + * characters should be sent to the @tty. + * + * Serialization including with @unthrottle() is the job of the ldisc + * layer. + * + * Optional: Always invoke via tty_throttle_safe(). Called under the + * @tty->termios_rwsem. + * + * @unthrottle: ``void ()(struct tty_struct *tty)`` + * + * This routine notifies the @tty driver that it should signal that + * characters can now be sent to the @tty without fear of overrunning the + * input buffers of the line disciplines. + * + * Optional. Always invoke via tty_unthrottle(). Called under the + * @tty->termios_rwsem. + * + * @stop: ``void ()(struct tty_struct *tty)`` + * + * This routine notifies the @tty driver that it should stop outputting + * characters to the tty device. + * + * Called with @tty->flow.lock held. Serialized with @start() method. + * + * Optional. Always invoke via stop_tty(). + * + * @start: ``void ()(struct tty_struct *tty)`` + * + * This routine notifies the @tty driver that it resumed sending + * characters to the @tty device. + * + * Called with @tty->flow.lock held. Serialized with stop() method. + * + * Optional. Always invoke via start_tty(). + * + * @hangup: ``void ()(struct tty_struct *tty)`` + * + * This routine notifies the @tty driver that it should hang up the @tty + * device. + * + * Optional. Called with tty lock held. + * + * @break_ctl: ``int ()(struct tty_struct *tty, int state)`` + * + * This optional routine requests the @tty driver to turn on or off BREAK + * status on the RS-232 port. If @state is -1, then the BREAK status + * should be turned on; if @state is 0, then BREAK should be turned off. + * + * If this routine is implemented, the high-level tty driver will handle + * the following ioctls: %TCSBRK, %TCSBRKP, %TIOCSBRK, %TIOCCBRK. + * + * If the driver sets %TTY_DRIVER_HARDWARE_BREAK in tty_alloc_driver(), + * then the interface will also be called with actual times and the + * hardware is expected to do the delay work itself. 0 and -1 are still + * used for on/off. + * + * Optional: Required for %TCSBRK/%BRKP/etc. handling. May sleep. + * + * @flush_buffer: ``void ()(struct tty_struct *tty)`` + * + * This routine discards device private output buffer. Invoked on close, + * hangup, to implement %TCOFLUSH ioctl and similar. + * + * Optional: if not provided, it is assumed there is no queue on the + * device. Do not call this function directly, call + * tty_driver_flush_buffer(). + * + * @wait_until_sent: ``void ()(struct tty_struct *tty, int timeout)`` + * + * This routine waits until the device has written out all of the + * characters in its transmitter FIFO. Or until @timeout (in jiffies) is + * reached. + * + * Optional: If not provided, the device is assumed to have no FIFO. + * Usually correct to invoke via tty_wait_until_sent(). May sleep. + * + * @send_xchar: ``void ()(struct tty_struct *tty, char ch)`` + * + * This routine is used to send a high-priority XON/XOFF character (@ch) + * to the @tty device. + * + * Optional: If not provided, then the @write method is called under + * the @tty->atomic_write_lock to keep it serialized with the ldisc. + * + * @tiocmget: ``int ()(struct tty_struct *tty)`` + * + * This routine is used to obtain the modem status bits from the @tty + * driver. + * + * Optional: If not provided, then %ENOTTY is returned from the %TIOCMGET + * ioctl. Do not call this function directly, call tty_tiocmget(). + * + * @tiocmset: ``int ()(struct tty_struct *tty, + * unsigned int set, unsigned int clear)`` + * + * This routine is used to set the modem status bits to the @tty driver. + * First, @clear bits should be cleared, then @set bits set. + * + * Optional: If not provided, then %ENOTTY is returned from the %TIOCMSET + * ioctl. Do not call this function directly, call tty_tiocmset(). + * + * @resize: ``int ()(struct tty_struct *tty, struct winsize *ws)`` + * + * Called when a termios request is issued which changes the requested + * terminal geometry to @ws. + * + * Optional: the default action is to update the termios structure + * without error. This is usually the correct behaviour. Drivers should + * not force errors here if they are not resizable objects (e.g. a serial + * line). See tty_do_resize() if you need to wrap the standard method + * in your own logic -- the usual case. + * + * @get_icount: ``int ()(struct tty_struct *tty, + * struct serial_icounter *icount)`` + * + * Called when the @tty device receives a %TIOCGICOUNT ioctl. Passed a + * kernel structure @icount to complete. + * + * Optional: called only if provided, otherwise %ENOTTY will be returned. + * + * @get_serial: ``int ()(struct tty_struct *tty, struct serial_struct *p)`` + * + * Called when the @tty device receives a %TIOCGSERIAL ioctl. Passed a + * kernel structure @p (&struct serial_struct) to complete. + * + * Optional: called only if provided, otherwise %ENOTTY will be returned. + * Do not call this function directly, call tty_tiocgserial(). + * + * @set_serial: ``int ()(struct tty_struct *tty, struct serial_struct *p)`` + * + * Called when the @tty device receives a %TIOCSSERIAL ioctl. Passed a + * kernel structure @p (&struct serial_struct) to set the values from. + * + * Optional: called only if provided, otherwise %ENOTTY will be returned. + * Do not call this function directly, call tty_tiocsserial(). + * + * @show_fdinfo: ``void ()(struct tty_struct *tty, struct seq_file *m)`` + * + * Called when the @tty device file descriptor receives a fdinfo request + * from VFS (to show in /proc/<pid>/fdinfo/). @m should be filled with + * information. + * + * Optional: called only if provided, otherwise nothing is written to @m. + * Do not call this function directly, call tty_show_fdinfo(). + * + * @poll_init: ``int ()(struct tty_driver *driver, int line, char *options)`` + * + * kgdboc support (Documentation/dev-tools/kgdb.rst). This routine is + * called to initialize the HW for later use by calling @poll_get_char or + * @poll_put_char. + * + * Optional: called only if provided, otherwise skipped as a non-polling + * driver. + * + * @poll_get_char: ``int ()(struct tty_driver *driver, int line)`` + * + * kgdboc support (see @poll_init). @driver should read a character from a + * tty identified by @line and return it. + * + * Optional: called only if @poll_init provided. + * + * @poll_put_char: ``void ()(struct tty_driver *driver, int line, char ch)`` + * + * kgdboc support (see @poll_init). @driver should write character @ch to + * a tty identified by @line. + * + * Optional: called only if @poll_init provided. + * + * @proc_show: ``int ()(struct seq_file *m, void *driver)`` + * + * Driver @driver (cast to &struct tty_driver) can show additional info in + * /proc/tty/driver/<driver_name>. It is enough to fill in the information + * into @m. + * + * Optional: called only if provided, otherwise no /proc entry created. + * + * This structure defines the interface between the low-level tty driver and + * the tty routines. These routines can be defined. Unless noted otherwise, + * they are optional, and can be filled in with a %NULL pointer. + */ +struct tty_operations { + struct tty_struct * (*lookup)(struct tty_driver *driver, + struct file *filp, int idx); + int (*install)(struct tty_driver *driver, struct tty_struct *tty); + void (*remove)(struct tty_driver *driver, struct tty_struct *tty); + int (*open)(struct tty_struct * tty, struct file * filp); + void (*close)(struct tty_struct * tty, struct file * filp); + void (*shutdown)(struct tty_struct *tty); + void (*cleanup)(struct tty_struct *tty); + int (*write)(struct tty_struct * tty, + const unsigned char *buf, int count); + int (*put_char)(struct tty_struct *tty, unsigned char ch); + void (*flush_chars)(struct tty_struct *tty); + unsigned int (*write_room)(struct tty_struct *tty); + unsigned int (*chars_in_buffer)(struct tty_struct *tty); + int (*ioctl)(struct tty_struct *tty, + unsigned int cmd, unsigned long arg); + long (*compat_ioctl)(struct tty_struct *tty, + unsigned int cmd, unsigned long arg); + void (*set_termios)(struct tty_struct *tty, const struct ktermios *old); + void (*throttle)(struct tty_struct * tty); + void (*unthrottle)(struct tty_struct * tty); + void (*stop)(struct tty_struct *tty); + void (*start)(struct tty_struct *tty); + void (*hangup)(struct tty_struct *tty); + int (*break_ctl)(struct tty_struct *tty, int state); + void (*flush_buffer)(struct tty_struct *tty); + void (*set_ldisc)(struct tty_struct *tty); + void (*wait_until_sent)(struct tty_struct *tty, int timeout); + void (*send_xchar)(struct tty_struct *tty, char ch); + int (*tiocmget)(struct tty_struct *tty); + int (*tiocmset)(struct tty_struct *tty, + unsigned int set, unsigned int clear); + int (*resize)(struct tty_struct *tty, struct winsize *ws); + int (*get_icount)(struct tty_struct *tty, + struct serial_icounter_struct *icount); + int (*get_serial)(struct tty_struct *tty, struct serial_struct *p); + int (*set_serial)(struct tty_struct *tty, struct serial_struct *p); + void (*show_fdinfo)(struct tty_struct *tty, struct seq_file *m); +#ifdef CONFIG_CONSOLE_POLL + int (*poll_init)(struct tty_driver *driver, int line, char *options); + int (*poll_get_char)(struct tty_driver *driver, int line); + void (*poll_put_char)(struct tty_driver *driver, int line, char ch); +#endif + int (*proc_show)(struct seq_file *m, void *driver); +} __randomize_layout; + +/** + * struct tty_driver -- driver for TTY devices + * + * @kref: reference counting. Reaching zero frees all the internals and the + * driver. + * @cdevs: allocated/registered character /dev devices + * @owner: modules owning this driver. Used drivers cannot be rmmod'ed. + * Automatically set by tty_alloc_driver(). + * @driver_name: name of the driver used in /proc/tty + * @name: used for constructing /dev node name + * @name_base: used as a number base for constructing /dev node name + * @major: major /dev device number (zero for autoassignment) + * @minor_start: the first minor /dev device number + * @num: number of devices allocated + * @type: type of tty driver (%TTY_DRIVER_TYPE_) + * @subtype: subtype of tty driver (%SYSTEM_TYPE_, %PTY_TYPE_, %SERIAL_TYPE_) + * @init_termios: termios to set to each tty initially (e.g. %tty_std_termios) + * @flags: tty driver flags (%TTY_DRIVER_) + * @proc_entry: proc fs entry, used internally + * @other: driver of the linked tty; only used for the PTY driver + * @ttys: array of active &struct tty_struct, set by tty_standard_install() + * @ports: array of &struct tty_port; can be set during initialization by + * tty_port_link_device() and similar + * @termios: storage for termios at each TTY close for the next open + * @driver_state: pointer to driver's arbitrary data + * @ops: driver hooks for TTYs. Set them using tty_set_operations(). Use &struct + * tty_port helpers in them as much as possible. + * @tty_drivers: used internally to link tty_drivers together + * + * The usual handling of &struct tty_driver is to allocate it by + * tty_alloc_driver(), set up all the necessary members, and register it by + * tty_register_driver(). At last, the driver is torn down by calling + * tty_unregister_driver() followed by tty_driver_kref_put(). + * + * The fields required to be set before calling tty_register_driver() include + * @driver_name, @name, @type, @subtype, @init_termios, and @ops. + */ +struct tty_driver { + struct kref kref; + struct cdev **cdevs; + struct module *owner; + const char *driver_name; + const char *name; + int name_base; + int major; + int minor_start; + unsigned int num; + short type; + short subtype; + struct ktermios init_termios; + unsigned long flags; + struct proc_dir_entry *proc_entry; + struct tty_driver *other; + + /* + * Pointer to the tty data structures + */ + struct tty_struct **ttys; + struct tty_port **ports; + struct ktermios **termios; + void *driver_state; + + /* + * Driver methods + */ + + const struct tty_operations *ops; + struct list_head tty_drivers; +} __randomize_layout; + +extern struct list_head tty_drivers; + +struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner, + unsigned long flags); +struct tty_driver *tty_find_polling_driver(char *name, int *line); + +void tty_driver_kref_put(struct tty_driver *driver); + +/* Use TTY_DRIVER_* flags below */ +#define tty_alloc_driver(lines, flags) \ + __tty_alloc_driver(lines, THIS_MODULE, flags) + +static inline struct tty_driver *tty_driver_kref_get(struct tty_driver *d) +{ + kref_get(&d->kref); + return d; +} + +static inline void tty_set_operations(struct tty_driver *driver, + const struct tty_operations *op) +{ + driver->ops = op; +} + +/** + * DOC: TTY Driver Flags + * + * TTY_DRIVER_RESET_TERMIOS + * Requests the tty layer to reset the termios setting when the last + * process has closed the device. Used for PTYs, in particular. + * + * TTY_DRIVER_REAL_RAW + * Indicates that the driver will guarantee not to set any special + * character handling flags if this is set for the tty: + * + * ``(IGNBRK || (!BRKINT && !PARMRK)) && (IGNPAR || !INPCK)`` + * + * That is, if there is no reason for the driver to + * send notifications of parity and break characters up to the line + * driver, it won't do so. This allows the line driver to optimize for + * this case if this flag is set. (Note that there is also a promise, if + * the above case is true, not to signal overruns, either.) + * + * TTY_DRIVER_DYNAMIC_DEV + * The individual tty devices need to be registered with a call to + * tty_register_device() when the device is found in the system and + * unregistered with a call to tty_unregister_device() so the devices will + * be show up properly in sysfs. If not set, all &tty_driver.num entries + * will be created by the tty core in sysfs when tty_register_driver() is + * called. This is to be used by drivers that have tty devices that can + * appear and disappear while the main tty driver is registered with the + * tty core. + * + * TTY_DRIVER_DEVPTS_MEM + * Don't use the standard arrays (&tty_driver.ttys and + * &tty_driver.termios), instead use dynamic memory keyed through the + * devpts filesystem. This is only applicable to the PTY driver. + * + * TTY_DRIVER_HARDWARE_BREAK + * Hardware handles break signals. Pass the requested timeout to the + * &tty_operations.break_ctl instead of using a simple on/off interface. + * + * TTY_DRIVER_DYNAMIC_ALLOC + * Do not allocate structures which are needed per line for this driver + * (&tty_driver.ports) as it would waste memory. The driver will take + * care. This is only applicable to the PTY driver. + * + * TTY_DRIVER_UNNUMBERED_NODE + * Do not create numbered ``/dev`` nodes. For example, create + * ``/dev/ttyprintk`` and not ``/dev/ttyprintk0``. Applicable only when a + * driver for a single tty device is being allocated. + */ +#define TTY_DRIVER_INSTALLED 0x0001 +#define TTY_DRIVER_RESET_TERMIOS 0x0002 +#define TTY_DRIVER_REAL_RAW 0x0004 +#define TTY_DRIVER_DYNAMIC_DEV 0x0008 +#define TTY_DRIVER_DEVPTS_MEM 0x0010 +#define TTY_DRIVER_HARDWARE_BREAK 0x0020 +#define TTY_DRIVER_DYNAMIC_ALLOC 0x0040 +#define TTY_DRIVER_UNNUMBERED_NODE 0x0080 + +/* tty driver types */ +#define TTY_DRIVER_TYPE_SYSTEM 0x0001 +#define TTY_DRIVER_TYPE_CONSOLE 0x0002 +#define TTY_DRIVER_TYPE_SERIAL 0x0003 +#define TTY_DRIVER_TYPE_PTY 0x0004 +#define TTY_DRIVER_TYPE_SCC 0x0005 /* scc driver */ +#define TTY_DRIVER_TYPE_SYSCONS 0x0006 + +/* system subtypes (magic, used by tty_io.c) */ +#define SYSTEM_TYPE_TTY 0x0001 +#define SYSTEM_TYPE_CONSOLE 0x0002 +#define SYSTEM_TYPE_SYSCONS 0x0003 +#define SYSTEM_TYPE_SYSPTMX 0x0004 + +/* pty subtypes (magic, used by tty_io.c) */ +#define PTY_TYPE_MASTER 0x0001 +#define PTY_TYPE_SLAVE 0x0002 + +/* serial subtype definitions */ +#define SERIAL_TYPE_NORMAL 1 + +int tty_register_driver(struct tty_driver *driver); +void tty_unregister_driver(struct tty_driver *driver); +struct device *tty_register_device(struct tty_driver *driver, unsigned index, + struct device *dev); +struct device *tty_register_device_attr(struct tty_driver *driver, + unsigned index, struct device *device, void *drvdata, + const struct attribute_group **attr_grp); +void tty_unregister_device(struct tty_driver *driver, unsigned index); + +#ifdef CONFIG_PROC_FS +void proc_tty_register_driver(struct tty_driver *); +void proc_tty_unregister_driver(struct tty_driver *); +#else +static inline void proc_tty_register_driver(struct tty_driver *d) {} +static inline void proc_tty_unregister_driver(struct tty_driver *d) {} +#endif + +#endif /* #ifdef _LINUX_TTY_DRIVER_H */ |