On Wed, Jun 16, 2021 at 08:18:01AM +0200, Jiri Slaby wrote: > On 10. 06. 21, 15:50, Lino Sanfilippo wrote: > > Add basic support for RS485: Provide a callback to configure rs485 > > settings. Handle the RS485 specific part in the functions > > pl011_rs485_tx_start() and pl011_rs485_tx_stop() which extend the generic > > start/stop callbacks. > > Beside via IOCTL from userspace RS485 can be enabled by means of the > > device tree property "rs485-enabled-at-boot-time". > > > > Signed-off-by: Lino Sanfilippo <LinoSanfilippo@xxxxxx> > > --- > > This patch has been tested with a Raspberry Pi CM3. > > > > drivers/tty/serial/amba-pl011.c | 143 +++++++++++++++++++++++++++++++- > > 1 file changed, 140 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c > > index 78682c12156a..36e8b938cdba 100644 > > --- a/drivers/tty/serial/amba-pl011.c > > +++ b/drivers/tty/serial/amba-pl011.c > ... > > @@ -1380,6 +1415,31 @@ static bool pl011_tx_char(struct uart_amba_port *uap, unsigned char c, > > return true; > > } > > +static void pl011_rs485_tx_start(struct uart_amba_port *uap) > > +{ > > + struct uart_port *port = &uap->port; > > + u32 cr; > > + > > + /* Enable transmitter */ > > + cr = pl011_read(uap, REG_CR); > > + cr |= UART011_CR_TXE; > > + /* Disable receiver if half-duplex */ > > + if (!(port->rs485.flags & SER_RS485_RX_DURING_TX)) > > + cr &= ~UART011_CR_RXE; > > + > > + if (port->rs485.flags & SER_RS485_RTS_ON_SEND) > > + cr &= ~UART011_CR_RTS; > > + else > > + cr |= UART011_CR_RTS; > > + > > + pl011_write(cr, uap, REG_CR); > > + > > + if (port->rs485.delay_rts_before_send) > > + mdelay(port->rs485.delay_rts_before_send); > > This is up to 1 second delay with interrupts disabled. Definitely not nice. > 8250 clamps this to 100 ms at least, why did you choose 1000 ms? > > > + > > + uap->rs485_tx_started = true; > > +} > > + > > /* Returns true if tx interrupts have to be (kept) enabled */ > > static bool pl011_tx_chars(struct uart_amba_port *uap, bool from_irq) > > { > ... > > @@ -1941,6 +2021,7 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios, > > unsigned int lcr_h, old_cr; > > unsigned long flags; > > unsigned int baud, quot, clkdiv; > > + unsigned int bits; > > if (uap->vendor->oversampling) > > clkdiv = 8; > > @@ -1968,25 +2049,32 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios, > > switch (termios->c_cflag & CSIZE) { > > case CS5: > > lcr_h = UART01x_LCRH_WLEN_5; > > + bits = 7; > > break; > > case CS6: > > lcr_h = UART01x_LCRH_WLEN_6; > > + bits = 8; > > break; > > case CS7: > > lcr_h = UART01x_LCRH_WLEN_7; > > + bits = 9; > > break; > > default: // CS8 > > lcr_h = UART01x_LCRH_WLEN_8; > > + bits = 10; > > break; > > } > > - if (termios->c_cflag & CSTOPB) > > + if (termios->c_cflag & CSTOPB) { > > lcr_h |= UART01x_LCRH_STP2; > > + bits++; > > + } > > if (termios->c_cflag & PARENB) { > > lcr_h |= UART01x_LCRH_PEN; > > if (!(termios->c_cflag & PARODD)) > > lcr_h |= UART01x_LCRH_EPS; > > if (termios->c_cflag & CMSPAR) > > lcr_h |= UART011_LCRH_SPS; > > + bits++; > > } > > You can do simply: > bits = tty_get_frame_size(termios->c_cflag); > now: > https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git/commit/?h=tty-testing&id=3ec2ff37230e1c961d4b0d0118dd23c46b5bcdbb I was wondering about that. I'll go drop this patch from my tty-next branch and wait for a new version that fixes the above delay issue and it can use this new call as well. thanks, greg k-h