tty: Add termiox

We need a way to describe the various additional modes and flow control
features that random weird hardware shows up and software such as wine
wants to emulate as Windows supports them.

TCGETX/TCSETX and the termiox ioctl are a SYS5 extension that we might as
well adopt. This patches adds the structures and the basic ioctl interfaces
when the TCGETX etc defines are added for an architecture. Drivers wishing
to use this stuff need to add new methods.

Signed-off-by: Alan Cox <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/char/tty_ioctl.c

···
 	return 0;
 }
 
+
+#ifdef TCGETX
+
+/**
+ *	set_termiox	-	set termiox fields if possible
+ *	@tty: terminal
+ *	@arg: termiox structure from user
+ *	@opt: option flags for ioctl type
+ *
+ *	Implement the device calling points for the SYS5 termiox ioctl
+ *	interface in Linux
+ */
+
+static int set_termiox(struct tty_struct *tty, void __user *arg, int opt)
+{
+	struct termiox tnew;
+	struct tty_ldisc *ld;
+
+	if (tty->termiox == NULL)
+		return -EINVAL;
+	if (copy_from_user(&tnew, arg, sizeof(struct termiox)))
+		return -EFAULT;
+
+	ld = tty_ldisc_ref(tty);
+	if (ld != NULL) {
+		if ((opt & TERMIOS_FLUSH) && ld->ops->flush_buffer)
+			ld->ops->flush_buffer(tty);
+		tty_ldisc_deref(ld);
+	}
+	if (opt & TERMIOS_WAIT) {
+		tty_wait_until_sent(tty, 0);
+		if (signal_pending(current))
+			return -EINTR;
+	}
+
+	mutex_lock(&tty->termios_mutex);
+	if (tty->ops->set_termiox)
+		tty->ops->set_termiox(tty, &tnew);
+	mutex_unlock(&tty->termios_mutex);
+	return 0;
+}
+
+#endif
+
 static unsigned long inq_canon(struct tty_struct *tty)
 {
 	int nr, head, tail;
···
 			return -EFAULT;
 			return 0;
 #endif
+#ifdef TCGETX
+	case TCGETX:
+		if (real_tty->termiox == NULL)
+			return -EINVAL;
+		if (copy_to_user(p, real_tty->termiox, sizeof(struct termiox)))
+			return -EFAULT;
+		return 0;
+	case TCSETX:
+		return set_termiox(real_tty, p, 0);
+	case TCSETXW:
+		return set_termiox(real_tty, p, TERMIOS_WAIT);
+	case TCSETXF:
+		return set_termiox(real_tty, p, TERMIOS_FLUSH);
+#endif		
 	case TIOCGSOFTCAR:
 		/* FIXME: for correctness we may need to take the termios
 		   lock here - review */

include/asm-x86/ioctls.h

···
 #define TIOCGPTN	_IOR('T', 0x30, unsigned int)
 				/* Get Pty Number (of pty-mux device) */
 #define TIOCSPTLCK	_IOW('T', 0x31, int)  /* Lock/unlock Pty */
+#define TCGETX		0x5432 /* SYS5 TCGETX compatibility */
+#define TCSETX		0x5433
+#define TCSETXF		0x5434
+#define TCSETXW		0x5435
 
 #define FIONCLEX	0x5450
 #define FIOCLEX		0x5451

include/linux/termios.h

···
 #include <linux/types.h>
 #include <asm/termios.h>
 
+#define NFF	5
+
+struct termiox
+{
+	__u16	x_hflag;
+	__u16	x_cflag;
+	__u16	x_rflag[NFF];
+	__u16	x_sflag;
+};
+
+#define	RTSXOFF		0x0001		/* RTS flow control on input */
+#define	CTSXON		0x0002		/* CTS flow control on output */
+#define	DTRXOFF		0x0004		/* DTR flow control on input */
+#define DSRXON		0x0008		/* DCD flow control on output */
+
 #endif

include/linux/tty.h

···
 	spinlock_t ctrl_lock;
 	/* Termios values are protected by the termios mutex */
 	struct ktermios *termios, *termios_locked;
+	struct termiox *termiox;	/* May be NULL for unsupported */
 	char name[64];
 	struct pid *pgrp;		/* Protected by ctrl lock */
 	struct pid *session;

include/linux/tty_driver.h

···
  *	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
  */
 
 #include <linux/fs.h>
···
 			unsigned int set, unsigned int clear);
 	int (*resize)(struct tty_struct *tty, struct tty_struct *real_tty,
 				struct winsize *ws);
+	int (*set_termiox)(struct tty_struct *tty, struct termiox *tnew);
 #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);