The struct 'tty_struct' has a callback to read the status flags of the tty
if the tty driver provides them. So fare, the data is transferred directly
to userspace with the function 'tty_tiocmget'. This function cannot be
used to evaluate the status line of the tty interface in the ledtrig-tty
trigger. To make this possible, a new function must be added that does
not immediately pass the data on to userspace.
The new function 'tty_get_tiocm' only returns the status register.
This information can then be processed further in the ledtrig-tty
trigger.
Signed-off-by: Florian Eckert <[email protected]>
---
drivers/tty/tty_io.c | 28 ++++++++++++++++++++++------
include/linux/tty.h | 1 +
2 files changed, 23 insertions(+), 6 deletions(-)
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 3299a5d50727..a12f63854ac4 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -2494,6 +2494,24 @@ static int send_break(struct tty_struct *tty, unsigned int duration)
return retval;
}
+/**
+ * tty_get_tiocm - get tiocm status register
+ * @tty: tty device
+ *
+ * Obtain the modem status bits from the tty driver if the feature
+ * is supported.
+ */
+int tty_get_tiocm(struct tty_struct *tty)
+{
+ int retval = -ENOTTY;
+
+ if (tty->ops->tiocmget)
+ retval = tty->ops->tiocmget(tty);
+
+ return retval;
+}
+EXPORT_SYMBOL_GPL(tty_get_tiocm);
+
/**
* tty_tiocmget - get modem status
* @tty: tty device
@@ -2506,14 +2524,12 @@ static int send_break(struct tty_struct *tty, unsigned int duration)
*/
static int tty_tiocmget(struct tty_struct *tty, int __user *p)
{
- int retval = -ENOTTY;
+ int retval;
- if (tty->ops->tiocmget) {
- retval = tty->ops->tiocmget(tty);
+ retval = tty_get_tiocm(tty);
+ if (retval >= 0)
+ retval = put_user(retval, p);
- if (retval >= 0)
- retval = put_user(retval, p);
- }
return retval;
}
diff --git a/include/linux/tty.h b/include/linux/tty.h
index f002d0f25db7..8e4d0b3b12b7 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -421,6 +421,7 @@ int tty_unthrottle_safe(struct tty_struct *tty);
int tty_do_resize(struct tty_struct *tty, struct winsize *ws);
int tty_get_icount(struct tty_struct *tty,
struct serial_icounter_struct *icount);
+int tty_get_tiocm(struct tty_struct *tty);
int is_current_pgrp_orphaned(void);
void tty_hangup(struct tty_struct *tty);
void tty_vhangup(struct tty_struct *tty);
--
2.30.2