On Mon, 27 Jun 2022, Chanho Park wrote: > Internal loopback mode can be supported by setting > S3C2443_UCON_LOOPBACK bit. The mode & bit can be supported since > s3c2410 and later SoCs. In that case, why is the LOOPBACK define named 2443 and not 2410??? The change looks fine otherwise. I note though that many of the current drivers won't return TOICM_LOOP from ->get_mctrl() but I don't think it's exactly wrong to return it either. Perhaps lack of returning it is due to Documentation/driver-api/serial/driver.rst not including TOICM_LOOP in get_mctrl's list of information but only in set_mctrl's one. -- i. > We can test it by linux-serial-test program[1] > with -k option. It will set TIOCM_LOOP mode during test. > > -k, --loopback Use internal hardware loop back > > [1]: https://github.com/cbrake/linux-serial-test > Signed-off-by: Chanho Park <chanho61.park@xxxxxxxxxxx> > --- > drivers/tty/serial/samsung_tty.c | 19 ++++++++++++++++--- > 1 file changed, 16 insertions(+), 3 deletions(-) > > diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c > index d5ca904def34..d7d035cd95c0 100644 > --- a/drivers/tty/serial/samsung_tty.c > +++ b/drivers/tty/serial/samsung_tty.c > @@ -1002,16 +1002,22 @@ static unsigned int s3c24xx_serial_tx_empty(struct uart_port *port) > static unsigned int s3c24xx_serial_get_mctrl(struct uart_port *port) > { > unsigned int umstat = rd_reg(port, S3C2410_UMSTAT); > + unsigned int ucon = rd_reg(port, S3C2410_UCON); > + unsigned int mctrl = TIOCM_CAR | TIOCM_DSR; > > if (umstat & S3C2410_UMSTAT_CTS) > - return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS; > - else > - return TIOCM_CAR | TIOCM_DSR; > + mctrl |= TIOCM_CTS; > + > + if (ucon & S3C2443_UCON_LOOPBACK) > + mctrl |= TIOCM_LOOP; > + > + return mctrl; > } > > static void s3c24xx_serial_set_mctrl(struct uart_port *port, unsigned int mctrl) > { > unsigned int umcon = rd_regl(port, S3C2410_UMCON); > + unsigned int ucon = rd_reg(port, S3C2410_UCON); > > if (mctrl & TIOCM_RTS) > umcon |= S3C2410_UMCOM_RTS_LOW; > @@ -1019,6 +1025,13 @@ static void s3c24xx_serial_set_mctrl(struct uart_port *port, unsigned int mctrl) > umcon &= ~S3C2410_UMCOM_RTS_LOW; > > wr_regl(port, S3C2410_UMCON, umcon); > + > + if (mctrl & TIOCM_LOOP) > + ucon |= S3C2443_UCON_LOOPBACK; > + else > + ucon &= ~S3C2443_UCON_LOOPBACK; > + > + wr_regl(port, S3C2410_UCON, ucon); > } > > static void s3c24xx_serial_break_ctl(struct uart_port *port, int break_state) >
