If a tty driver wants to notify the user of some exceptional event,
such as a usb cdc acm device set_line_coding event, it needs a way to
modify the mask returned by poll() and possible also add wait queues.
In order to do that, we allow the driver to supply a poll() callback
of its own, which will be called in n_tty_poll().
Signed-off-by: Tal Shorer <tal.shorer@xxxxxxxxx>
---
drivers/tty/n_tty.c | 2 ++
include/linux/tty_driver.h | 3 +++
2 files changed, 5 insertions(+)
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index bdf0e6e..7af8c29 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -2394,6 +2394,8 @@ static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
tty_write_room(tty) > 0)
mask |= POLLOUT | POLLWRNORM;
+ if (tty->ops->poll)
+ mask |= tty->ops->poll(tty, file, wait);
return mask;
}
diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index b742b5e..630ef03 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -243,6 +243,7 @@
#include <linux/list.h>
#include <linux/cdev.h>
#include <linux/termios.h>
+#include <linux/poll.h>
struct tty_struct;
struct tty_driver;
@@ -285,6 +286,8 @@ struct tty_operations {
int (*set_termiox)(struct tty_struct *tty, struct termiox *tnew);
int (*get_icount)(struct tty_struct *tty,
struct serial_icounter_struct *icount);
+ unsigned int (*poll)(struct tty_struct *tty, struct file *file,
+ poll_table *wait);
#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);
--
2.7.4
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