On Wed, Apr 22, 2020 at 9:05 PM <sean.wang@xxxxxxxxxxxx> wrote:
>
> From: Sean Wang <sean.wang@xxxxxxxxxxxx>
>
> Bluetooth Interface (BTIF) is designed dedicatedly for MediaTek SOC with
> BT in order to be instead of the UART interface between BT module and Host
> CPU, and not exported to user space to access.
>
> As the UART design, BTIF will be an APB slave and can transmit or receive
> data by MCU access, but doesn't provide termios function like baudrate and
> flow control setup.
>
> Even LCR on offset 0xC that is just a FAKELCR
> a. If FAKELCR[7] is equaled to 1, RBR(0x00), THR(0x00), IER(0x04)
> will not be readable/writable.
>
> b. If FAKELCR is equaled to 0xBF, RBR(0x00), THR(0x00), IER(0x04),
> IIR(0x08), and LSR(0x14) will not be readable/writable.
>
> So adding a new capability 'UART_CAP_NTIO' for the unusual unsupported
> case.
>
> Fixes: 1c16ae65e250 ("serial: 8250: of: Add new port type for MediaTek BTIF controller on MT7622/23 SoC")
> Cc: Steven Liu <steven.liu@xxxxxxxxxxxx>
> Suggested-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
I didn't suggest this change. I only commented on the name of the macro.
> Signed-off-by: Sean Wang <sean.wang@xxxxxxxxxxxx>
> Signed-off-by: Ryder Lee <ryder.lee@xxxxxxxxxxxx>
>
> --
> v1->v2:
> no change on termios->c_cflag and refine commit message
>
> v2->v3:
> change the naming from NMOD to NTIO as TIO is a well established prefix
> for termios IOCTLs.
> ---
> drivers/tty/serial/8250/8250.h | 1 +
> drivers/tty/serial/8250/8250_port.c | 5 ++++-
> 2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
> index 33ad9d6de532..234d8db470c0 100644
> --- a/drivers/tty/serial/8250/8250.h
> +++ b/drivers/tty/serial/8250/8250.h
> @@ -82,6 +82,7 @@ struct serial8250_config {
> #define UART_CAP_MINI (1 << 17) /* Mini UART on BCM283X family lacks:
> * STOP PARITY EPAR SPAR WLEN5 WLEN6
> */
> +#define UART_CAP_NTIO (1 << 18) /* UART doesn't do termios */
>
> #define UART_BUG_QUOT (1 << 0) /* UART has buggy quot LSB */
> #define UART_BUG_TXEN (1 << 1) /* UART has buggy TX IIR status */
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index 0325f2e53b74..abc974b4113f 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -286,7 +286,7 @@ static const struct serial8250_config uart_config[] = {
> .tx_loadsz = 16,
> .fcr = UART_FCR_ENABLE_FIFO |
> UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT,
> - .flags = UART_CAP_FIFO,
> + .flags = UART_CAP_FIFO | UART_CAP_NTIO,
> },
> [PORT_NPCM] = {
> .name = "Nuvoton 16550",
> @@ -2544,6 +2544,9 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
> unsigned long flags;
> unsigned int baud, quot, frac = 0;
>
> + if (up->capabilities & UART_CAP_NTIO)
> + return;
> +
> if (up->capabilities & UART_CAP_MINI) {
> termios->c_cflag &= ~(CSTOPB | PARENB | PARODD | CMSPAR);
> if ((termios->c_cflag & CSIZE) == CS5 ||
> --
> 2.25.1
--
With Best Regards,
Andy Shevchenko
