[PATCH 3/5] serial/8250: export serial8250_read_char

[Eddie James]

On 03/20/2018 09:52 PM, Jeremy Kerr wrote:
> Currently, we export serial8250_rx_chars, which does a whole bunch of
> reads from the 8250 data register, without any form of flow control
> between reads.
>
> An upcoming change to the aspeed vuart driver implements more
> fine-grained flow control in the interrupt handler, requiring
> character-at-a-time control over the rx path.
>
> This change exports serial8250_read_char to allow this.

Tested-by: Eddie James <eajames at linux.vnet.ibm.com>

>
> Signed-off-by: Jeremy Kerr <jk at ozlabs.org>
> ---
>   drivers/tty/serial/8250/8250_port.c | 3 ++-
>   include/linux/serial_8250.h         | 1 +
>   2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index a5fe0e66c607..ea435406936c 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -1650,7 +1650,7 @@ static void serial8250_enable_ms(struct uart_port *port)
>   	serial8250_rpm_put(up);
>   }
>
> -static void serial8250_read_char(struct uart_8250_port *up, unsigned char lsr)
> +void serial8250_read_char(struct uart_8250_port *up, unsigned char lsr)
>   {
>   	struct uart_port *port = &up->port;
>   	unsigned char ch;
> @@ -1710,6 +1710,7 @@ static void serial8250_read_char(struct uart_8250_port *up, unsigned char lsr)
>
>   	uart_insert_char(port, lsr, UART_LSR_OE, ch, flag);
>   }
> +EXPORT_SYMBOL_GPL(serial8250_read_char);
>
>   /*
>    * serial8250_rx_chars: processes according to the passed in LSR
> diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
> index 61fbb440449c..4639a3608614 100644
> --- a/include/linux/serial_8250.h
> +++ b/include/linux/serial_8250.h
> @@ -162,6 +162,7 @@ extern void serial8250_do_set_mctrl(struct uart_port *port, unsigned int mctrl);
>   extern int fsl8250_handle_irq(struct uart_port *port);
>   int serial8250_handle_irq(struct uart_port *port, unsigned int iir);
>   unsigned char serial8250_rx_chars(struct uart_8250_port *up, unsigned char lsr);
> +void serial8250_read_char(struct uart_8250_port *up, unsigned char lsr);
>   void serial8250_tx_chars(struct uart_8250_port *up);
>   unsigned int serial8250_modem_status(struct uart_8250_port *up);
>   void serial8250_init_port(struct uart_8250_port *up);