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tty: cp210x: Fix carrier handling 

Original discussion:
http://thread.gmane.org/gmane.linux.usb.general/23217/focus=23248
or
http://marc.info/?l=linux-usb&m=125553790714133&w=2

9a68e39d4a broke carrier handling so that a
cp210x setup which needed the carrier lines set up (non CLOCAL) which did
not make a call which set the termios bits left the lines down even if
CLOCAL was not asserted.

Fix this not by reverting but by adding the proper dtr_rts and
carrier_raised methods. This both sets the modem lines properly and also
implements the correct blocking semantics for the port as required by
POSIX.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Reported-by: Karl Hiramoto <karl@hiramoto.org>
Tested-by:  Karl Hiramoto <karl@hiramoto.org>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Cox 2009-10-28 21:12:33 +01:00 committed by Greg Kroah-Hartman
parent 4175f3e31c
commit d94c7bd4c1
1 changed files with 21 additions and 0 deletions
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21
drivers/usb/serial/cp210x.c
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@ -50,6 +50,8 @@ static int cp210x_tiocmset_port(struct usb_serial_port *port, struct file *,
static void cp210x_break_ctl(struct tty_struct *, int);
static int cp210x_startup(struct usb_serial *);
static void cp210x_disconnect(struct usb_serial *);
static void cp210x_dtr_rts(struct usb_serial_port *p, int on);
static int cp210x_carrier_raised(struct usb_serial_port *p);
static int debug;
@ -143,6 +145,8 @@ static struct usb_serial_driver cp210x_device = {
.tiocmset = cp210x_tiocmset,
.attach = cp210x_startup,
.disconnect = cp210x_disconnect,
.dtr_rts = cp210x_dtr_rts,
.carrier_raised = cp210x_carrier_raised
};
/* Config request types */
@ -746,6 +750,14 @@ static int cp210x_tiocmset_port(struct usb_serial_port *port, struct file *file,
return cp210x_set_config(port, CP210X_SET_MHS, &control, 2);
}
static void cp210x_dtr_rts(struct usb_serial_port *p, int on)
{
if (on)
cp210x_tiocmset_port(p, NULL, TIOCM_DTR|TIOCM_RTS, 0);
else
cp210x_tiocmset_port(p, NULL, 0, TIOCM_DTR|TIOCM_RTS);
}
static int cp210x_tiocmget (struct tty_struct *tty, struct file *file)
{
struct usb_serial_port *port = tty->driver_data;
@ -768,6 +780,15 @@ static int cp210x_tiocmget (struct tty_struct *tty, struct file *file)
return result;
}
static int cp210x_carrier_raised(struct usb_serial_port *p)
{
unsigned int control;
cp210x_get_config(p, CP210X_GET_MDMSTS, &control, 1);
if (control & CONTROL_DCD)
return 1;
return 0;
}
static void cp210x_break_ctl (struct tty_struct *tty, int break_state)
{
struct usb_serial_port *port = tty->driver_data;