| Message ID | 20231019112809.881730-3-fe@dev.tdt.de |
|---|---|
| State | Superseded |
| Headers | show |
| Series | ledtrig-tty: add additional tty state evaluation | expand |
On Thu, Oct 19, 2023 at 01:28:08PM +0200, Florian Eckert wrote: > 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. Writing changelogs are hard. You are including a lot of information in here that really doesn't need to be, as you are focusing on your specific use case, which is fine, but you are creating a generic function. This can be simpler, how about something like this: There is no in-kernel function to get the status register of a tty device like the TIOCMGET ioctl returns to userspace. Create a new function, tty_get_tiocm(), to obtain the status register that other portions of the kernel can call if they need this information, and move the existing internal tty_tiocmget() function to use this interface. Sound good? The code portion looks fine to me, thanks for doing this. greg k-h
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);
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 <fe@dev.tdt.de> --- drivers/tty/tty_io.c | 28 ++++++++++++++++++++++------ include/linux/tty.h | 1 + 2 files changed, 23 insertions(+), 6 deletions(-)