From: Philippe Schenker <philippe.schenker@xxxxxxxxxxx> Sent: Wednesday, October 16, 2019 11:19 PM
> This commits adds RS485 support for LPUART hardware that uses 32-bit
> registers. These are typically found in i.MX8 processors.
>
> Signed-off-by: Philippe Schenker <philippe.schenker@xxxxxxxxxxx>
Reviewed-by: Fugang Duan <fugang.duan@xxxxxxx>
>
> ---
>
> drivers/tty/serial/fsl_lpuart.c | 65 ++++++++++++++++++++++++++++++++-
> 1 file changed, 63 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index
> 346b4a070ce9..22df5f8f48b6 100644
> --- a/drivers/tty/serial/fsl_lpuart.c
> +++ b/drivers/tty/serial/fsl_lpuart.c
> @@ -1280,6 +1280,57 @@ static int lpuart_config_rs485(struct uart_port
> *port,
> return 0;
> }
>
> +static int lpuart32_config_rs485(struct uart_port *port,
> + struct serial_rs485 *rs485) {
> + struct lpuart_port *sport = container_of(port,
> + struct lpuart_port, port);
> +
> + unsigned long modem = lpuart32_read(&sport->port, UARTMODIR)
> + & ~(UARTMODEM_TXRTSPOL |
> UARTMODEM_TXRTSE);
> + lpuart32_write(&sport->port, modem, UARTMODIR);
> +
> + /* clear unsupported configurations */
> + rs485->delay_rts_before_send = 0;
> + rs485->delay_rts_after_send = 0;
> + rs485->flags &= ~SER_RS485_RX_DURING_TX;
> +
> + if (rs485->flags & SER_RS485_ENABLED) {
> + /* Enable auto RS-485 RTS mode */
> + modem |= UARTMODEM_TXRTSE;
> +
> + /*
> + * RTS needs to be logic HIGH either during transer _or_
> after
> + * transfer, other variants are not supported by the
> hardware.
> + */
> +
> + if (!(rs485->flags & (SER_RS485_RTS_ON_SEND |
> + SER_RS485_RTS_AFTER_SEND)))
> + rs485->flags |= SER_RS485_RTS_ON_SEND;
> +
> + if (rs485->flags & SER_RS485_RTS_ON_SEND &&
> + rs485->flags &
> SER_RS485_RTS_AFTER_SEND)
> + rs485->flags &=
> ~SER_RS485_RTS_AFTER_SEND;
> +
> + /*
> + * The hardware defaults to RTS logic HIGH while
> transfer.
> + * Switch polarity in case RTS shall be logic HIGH
> + * after transfer.
> + * Note: UART is assumed to be active high.
> + */
> + if (rs485->flags & SER_RS485_RTS_ON_SEND)
> + modem &= ~UARTMODEM_TXRTSPOL;
> + else if (rs485->flags & SER_RS485_RTS_AFTER_SEND)
> + modem |= UARTMODEM_TXRTSPOL;
> + }
> +
> + /* Store the new configuration */
> + sport->port.rs485 = *rs485;
> +
> + lpuart32_write(&sport->port, modem, UARTMODIR);
> + return 0;
> +}
> +
> static unsigned int lpuart_get_mctrl(struct uart_port *port) {
> unsigned int temp = 0;
> @@ -1878,6 +1929,13 @@ lpuart32_set_termios(struct uart_port *port,
> struct ktermios *termios,
> ctrl |= UARTCTRL_M;
> }
>
> + /*
> + * When auto RS-485 RTS mode is enabled,
> + * hardware flow control need to be disabled.
> + */
> + if (sport->port.rs485.flags & SER_RS485_ENABLED)
> + termios->c_cflag &= ~CRTSCTS;
> +
> if (termios->c_cflag & CRTSCTS) {
> modem |= (UARTMODIR_RXRTSE |
> UARTMODIR_TXCTSE);
> } else {
> @@ -2405,7 +2463,10 @@ static int lpuart_probe(struct platform_device
> *pdev)
> sport->port.ops = &lpuart_pops;
> sport->port.flags = UPF_BOOT_AUTOCONF;
>
> - sport->port.rs485_config = lpuart_config_rs485;
> + if (lpuart_is_32(sport))
> + sport->port.rs485_config = lpuart32_config_rs485;
> + else
> + sport->port.rs485_config = lpuart_config_rs485;
>
> sport->ipg_clk = devm_clk_get(&pdev->dev, "ipg");
> if (IS_ERR(sport->ipg_clk)) {
> @@ -2459,7 +2520,7 @@ static int lpuart_probe(struct platform_device
> *pdev)
> sport->port.rs485.delay_rts_after_send)
> dev_err(&pdev->dev, "driver doesn't support RTS
> delays\n");
>
> - lpuart_config_rs485(&sport->port, &sport->port.rs485);
> + sport->port.rs485_config(&sport->port, &sport->port.rs485);
>
> sport->dma_tx_chan =
> dma_request_slave_channel(sport->port.dev, "tx");
> if (!sport->dma_tx_chan)
> --
> 2.23.0
