v4.19.13 snapshot.
diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
new file mode 100644
index 0000000..71dbc89
--- /dev/null
+++ b/include/linux/tty_driver.h
@@ -0,0 +1,443 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_TTY_DRIVER_H
+#define _LINUX_TTY_DRIVER_H
+
+/*
+ * This structure defines the interface between the low-level tty
+ * driver 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.
+ *
+ * struct tty_struct * (*lookup)(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 ttys array
+ *
+ * int (*install)(struct tty_driver *self, struct tty_struct *tty)
+ *
+ * Install a new tty into the tty driver internal tables. Used in
+ * conjunction with lookup and remove methods.
+ *
+ * Optional method. Default behaviour is to use the ttys array
+ *
+ * void (*remove)(struct tty_driver *self, struct tty_struct *tty)
+ *
+ * Remove a closed tty from the tty driver internal tables. Used in
+ * conjunction with lookup and remove methods.
+ *
+ * Optional method. Default behaviour is to use the ttys array
+ *
+ * int (*open)(struct tty_struct * tty, struct file * filp);
+ *
+ * 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.
+ *
+ * void (*close)(struct tty_struct * tty, struct file * filp);
+ *
+ * This routine is called when a particular tty device is closed.
+ * Note: called even if the corresponding open() failed.
+ *
+ * Required method. Called with tty lock held.
+ *
+ * void (*shutdown)(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.
+ *
+ * void (*cleanup)(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.
+ *
+ *
+ * int (*write)(struct tty_struct * tty,
+ * const unsigned char *buf, int count);
+ *
+ * This routine is called by the kernel to write a series of
+ * characters 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.
+ *
+ * Optional: Required for writable devices.
+ *
+ * int (*put_char)(struct tty_struct *tty, unsigned char ch);
+ *
+ * This routine is called by the kernel to write a single
+ * character 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.
+ *
+ * Note: Do not call this function directly, call tty_put_char
+ *
+ * void (*flush_chars)(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:
+ *
+ * Note: Do not call this function directly, call tty_driver_flush_chars
+ *
+ * int (*write_room)(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.
+ *
+ * Required if write method is provided else not needed.
+ *
+ * Note: Do not call this function directly, call tty_write_room
+ *
+ * int (*ioctl)(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
+ *
+ * long (*compat_ioctl)(struct tty_struct *tty,,
+ * unsigned int cmd, unsigned long arg);
+ *
+ * implement ioctl processing for 32 bit process on 64 bit system
+ *
+ * Optional
+ *
+ * void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
+ *
+ * This routine allows the tty driver to be notified when
+ * device's termios settings have changed.
+ *
+ * Optional: Called under the termios lock
+ *
+ *
+ * void (*set_ldisc)(struct tty_struct *tty);
+ *
+ * This routine allows the tty driver to be notified when the
+ * device's termios settings have changed.
+ *
+ * Optional: Called under BKL (currently)
+ *
+ * void (*throttle)(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.
+ *
+ * Optional: Always invoke via tty_throttle(), called under the
+ * termios lock.
+ *
+ * void (*unthrottle)(struct tty_struct * tty);
+ *
+ * This routine notifies the tty drivers that it should signals
+ * 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
+ * termios lock.
+ *
+ * void (*stop)(struct tty_struct *tty);
+ *
+ * This routine notifies the tty driver that it should stop
+ * outputting characters to the tty device.
+ *
+ * Called with ->flow_lock held. Serialized with start() method.
+ *
+ * Optional:
+ *
+ * Note: Call stop_tty not this method.
+ *
+ * void (*start)(struct tty_struct *tty);
+ *
+ * This routine notifies the tty driver that it resume sending
+ * characters to the tty device.
+ *
+ * Called with ->flow_lock held. Serialized with stop() method.
+ *
+ * Optional:
+ *
+ * Note: Call start_tty not this method.
+ *
+ * void (*hangup)(struct tty_struct *tty);
+ *
+ * This routine notifies the tty driver that it should hang up the
+ * tty device.
+ *
+ * Optional:
+ *
+ * Called with tty lock held.
+ *
+ * int (*break_ctl)(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 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.
+ *
+ * void (*wait_until_sent)(struct tty_struct *tty, int timeout);
+ *
+ * This routine waits until the device has written out all of the
+ * characters in its transmitter FIFO.
+ *
+ * Optional: If not provided the device is assumed to have no FIFO
+ *
+ * Note: Usually correct to call tty_wait_until_sent
+ *
+ * void (*send_xchar)(struct tty_struct *tty, char ch);
+ *
+ * This routine is used to send a high-priority XON/XOFF
+ * character to the device.
+ *
+ * Optional: If not provided then the write method is called under
+ * the atomic write lock to keep it serialized with the ldisc.
+ *
+ * int (*resize)(struct tty_struct *tty, struct winsize *ws)
+ *
+ * Called when a termios request is issued which changes the
+ * requested terminal geometry.
+ *
+ * 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 (eg a serial
+ * line). See tty_do_resize() if you need to wrap the standard method
+ * in your own logic - the usual case.
+ *
+ * void (*set_termiox)(struct tty_struct *tty, struct termiox *new);
+ *
+ * Called when the device receives a termiox based ioctl. Passes down
+ * the requested data from user space. This method will not be invoked
+ * unless the tty also has a valid tty->termiox pointer.
+ *
+ * Optional: Called under the termios lock
+ *
+ * int (*get_icount)(struct tty_struct *tty, struct serial_icounter *icount);
+ *
+ * Called when the device receives a TIOCGICOUNT ioctl. Passed a kernel
+ * structure to complete. This method is optional and will only be called
+ * if provided (otherwise EINVAL will be returned).
+ */
+
+#include <linux/export.h>
+#include <linux/fs.h>
+#include <linux/list.h>
+#include <linux/cdev.h>
+#include <linux/termios.h>
+#include <linux/seq_file.h>
+
+struct tty_struct;
+struct tty_driver;
+struct serial_icounter_struct;
+
+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);
+ int (*write_room)(struct tty_struct *tty);
+ 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, 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 (*set_termiox)(struct tty_struct *tty, struct termiox *tnew);
+ int (*get_icount)(struct tty_struct *tty,
+ struct serial_icounter_struct *icount);
+ 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 *, void *);
+} __randomize_layout;
+
+struct tty_driver {
+ int magic; /* magic number for this structure */
+ struct kref kref; /* Reference management */
+ struct cdev **cdevs;
+ struct module *owner;
+ const char *driver_name;
+ const char *name;
+ int name_base; /* offset of printed name */
+ int major; /* major device number */
+ int minor_start; /* start of minor device number */
+ unsigned int num; /* number of devices allocated */
+ short type; /* type of tty driver */
+ short subtype; /* subtype of tty driver */
+ struct ktermios init_termios; /* Initial termios */
+ unsigned long flags; /* tty driver flags */
+ struct proc_dir_entry *proc_entry; /* /proc fs entry */
+ struct tty_driver *other; /* only used for the PTY driver */
+
+ /*
+ * 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;
+
+extern struct tty_driver *__tty_alloc_driver(unsigned int lines,
+ struct module *owner, unsigned long flags);
+extern void put_tty_driver(struct tty_driver *driver);
+extern void tty_set_operations(struct tty_driver *driver,
+ const struct tty_operations *op);
+extern struct tty_driver *tty_find_polling_driver(char *name, int *line);
+
+extern 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)
+
+/*
+ * DEPRECATED Do not use this in new code, use tty_alloc_driver instead.
+ * (And change the return value checks.)
+ */
+static inline struct tty_driver *alloc_tty_driver(unsigned int lines)
+{
+ struct tty_driver *ret = tty_alloc_driver(lines, 0);
+ if (IS_ERR(ret))
+ return NULL;
+ return ret;
+}
+
+static inline struct tty_driver *tty_driver_kref_get(struct tty_driver *d)
+{
+ kref_get(&d->kref);
+ return d;
+}
+
+/* tty driver magic number */
+#define TTY_DRIVER_MAGIC 0x5402
+
+/*
+ * 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 PTY's, in particular.
+ *
+ * TTY_DRIVER_REAL_RAW --- if set, indicates that the driver will
+ * guarantee never not to set any special character handling
+ * flags if ((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 --- if set, 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, 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, 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 caller instead of using a simple
+ * on/off interface.
+ *
+ * TTY_DRIVER_DYNAMIC_ALLOC -- do not allocate structures which are
+ * needed per line for this driver as it would waste memory.
+ * The driver will take care.
+ *
+ * TTY_DRIVER_UNNUMBERED_NODE -- do not create numbered /dev nodes. In
+ * other words 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
+
+#endif /* #ifdef _LINUX_TTY_DRIVER_H */