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charset="utf-8" Moxa PCIe boards require a specific sequence to send break signals in RS485 mode. This patch implements the required behavior, while falling back to the default break mechanism in RS232 and RS422 modes. Signed-off-by: Crescent Hsieh --- drivers/tty/serial/8250/8250_mxpcie.c | 52 +++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) diff --git a/drivers/tty/serial/8250/8250_mxpcie.c b/drivers/tty/serial/825= 0/8250_mxpcie.c index 5d1097c166e4..9ba171274221 100644 --- a/drivers/tty/serial/8250/8250_mxpcie.c +++ b/drivers/tty/serial/8250/8250_mxpcie.c @@ -40,6 +40,7 @@ =20 /* Special Function Register (SFR) */ #define MOXA_PUART_SFR 0x07 +#define MOXA_PUART_SFR_FORCE_TX BIT(0) #define MOXA_PUART_SFR_950 BIT(5) =20 /* Enhanced Function Register (EFR) */ @@ -390,6 +391,56 @@ static int mxpcie8250_handle_irq(struct uart_port *por= t) return 1; } =20 +static void mxpcie8250_software_break_ctl(struct uart_port *port, int brea= k_state) +{ + struct uart_8250_port *up =3D up_to_u8250p(port); + struct tty_struct *tty =3D port->state->port.tty; + unsigned char tx_byte =3D 0x01; + unsigned int baud, quot; + unsigned long flags; + u8 sfr; + + uart_port_lock_irqsave(port, &flags); + + if (break_state =3D=3D -1) { + serial_out(up, UART_LCR, up->lcr | UART_LCR_DLAB); + serial_out(up, UART_DLL, 0); + serial_out(up, UART_DLM, 0); + serial_out(up, UART_LCR, up->lcr); + + memcpy(port->membase + MOXA_PUART_TX_FIFO_MEM, &tx_byte, 1); + + sfr =3D serial_in(up, MOXA_PUART_SFR); + serial_out(up, MOXA_PUART_SFR, sfr | MOXA_PUART_SFR_FORCE_TX); + + up->lcr |=3D UART_LCR_SBC; + serial_out(up, UART_LCR, up->lcr); + } else { + up->lcr &=3D ~UART_LCR_SBC; + serial_out(up, UART_LCR, up->lcr); + + sfr =3D serial_in(up, MOXA_PUART_SFR); + serial_out(up, MOXA_PUART_SFR, sfr &=3D ~MOXA_PUART_SFR_FORCE_TX); + + serial_out(up, UART_FCR, UART_FCR_CLEAR_XMIT); + + baud =3D tty_get_baud_rate(tty); + quot =3D uart_get_divisor(port, baud); + serial8250_do_set_divisor(port, baud, quot); + serial_out(up, UART_LCR, up->lcr); + } + uart_port_unlock_irqrestore(port, flags); +} + +static void mxpcie8250_break_ctl(struct uart_port *port, int break_state) +{ + if (port->rs485.flags & SER_RS485_ENABLED && + !(port->rs485.flags & SER_RS485_MODE_RS422)) + mxpcie8250_software_break_ctl(port, break_state); + else + serial8250_do_break_ctl(port, break_state); +} + static int mxpcie8250_init(struct pci_dev *pdev) { resource_size_t iobar_addr =3D pci_resource_start(pdev, 2); @@ -487,6 +538,7 @@ static int mxpcie8250_probe(struct pci_dev *pdev, const= struct pci_device_id *id up.port.throttle =3D mxpcie8250_throttle; up.port.unthrottle =3D mxpcie8250_unthrottle; up.port.handle_irq =3D mxpcie8250_handle_irq; + up.port.break_ctl =3D mxpcie8250_break_ctl; =20 for (i =3D 0; i < num_ports; i++) { if (mxpcie8250_setup(pdev, priv, &up, i)) --=20 2.45.2