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
thanks,
--
js
