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serial: 8250_mxpcie: enable automatic RTS/CTS flow control

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The MUEx50 UART supports automatic RTS/CTS flow control via the enhanced
feature register.

Implement a mxpcie-specific set_termios() callback that enables MUEx50
auto-RTS/auto-CTS when CRTSCTS is requested and disables it otherwise.
Keep the 8250 port status flags in sync with the hardware configuration.

Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
Link: https://patch.msgid.link/20260731074820.735619-5-crescentcy.hsieh@moxa.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Crescent Hsieh 2026-07-31 15:48:10 +08:00 committed by Greg Kroah-Hartman
parent 0a53c72969
commit 55edf8511f
1 changed files with 28 additions and 0 deletions
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28
drivers/tty/serial/8250/8250_mxpcie.c
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@ -58,6 +58,10 @@
/* Enhanced Function Register (EFR) */
#define MOXA_PUART_EFR 0x0A
#define MOXA_PUART_EFR_ENHANCED BIT(4)
#define MOXA_PUART_EFR_AUTO_RTS BIT(6)
#define MOXA_PUART_EFR_AUTO_CTS BIT(7)
#define MOXA_PUART_EFR_RX_FLOW_MASK GENMASK(1, 0)
#define MOXA_PUART_EFR_TX_FLOW_MASK GENMASK(3, 2)
#define MOXA_PUART_TTL 0x10 /* Tx Interrupt Trigger Level */
#define MOXA_PUART_RTL 0x11 /* Rx Interrupt Trigger Level */
@ -148,6 +152,29 @@ static void mxpcie8250_set_interface(struct mxpcie8250 *priv,
iowrite8(cval, uir_addr);
}
static void mxpcie8250_set_termios(struct uart_port *port,
struct ktermios *new,
const struct ktermios *old)
{
struct uart_8250_port *up = up_to_u8250p(port);
struct tty_struct *tty = port->state->port.tty;
unsigned int cflag = tty->termios.c_cflag;
u8 efr;
serial8250_do_set_termios(port, new, old);
up->port.status &= ~(UPSTAT_AUTORTS | UPSTAT_AUTOCTS);
efr = serial_in(up, MOXA_PUART_EFR);
efr &= ~(MOXA_PUART_EFR_AUTO_RTS | MOXA_PUART_EFR_AUTO_CTS);
if (cflag & CRTSCTS) {
efr |= (MOXA_PUART_EFR_AUTO_RTS | MOXA_PUART_EFR_AUTO_CTS);
up->port.status |= (UPSTAT_AUTORTS | UPSTAT_AUTOCTS);
}
serial_out(up, MOXA_PUART_EFR, efr);
}
static int mxpcie8250_startup(struct uart_port *port)
{
struct uart_8250_port *up = up_to_u8250p(port);
@ -285,6 +312,7 @@ static int mxpcie8250_probe(struct pci_dev *pdev, const struct pci_device_id *id
up.port.iobase = 0;
up.port.regshift = 0;
up.port.set_termios = mxpcie8250_set_termios;
up.port.startup = mxpcie8250_startup;
up.port.shutdown = mxpcie8250_shutdown;