On Thu, Jan 14, 2021 at 08:28:30PM +0800, zhangqiumiao1@xxxxxxxxxx wrote:
> From: Qiumiao Zhang <zhangqiumiao1@xxxxxxxxxx>
>
> make pl011 serial port support 485 mode full duplex communication
>
> Signed-off-by: Qiumiao Zhang <zhangqiumiao1@xxxxxxxxxx>
> ---
> Changes in v3:
> -Fix busy loop forever in pl011_tx_empty
> -Move the definition of cr into uart_amba_port
> -run checkpatch with no error or warning
>
> Changes in v2:
> -Fix two compilation errors
>
> drivers/tty/serial/amba-pl011.c | 32 ++++++++++++++++++++++++++++++++
> 1 file changed, 32 insertions(+)
>
> diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
> index c255476..9da10a4 100644
> --- a/drivers/tty/serial/amba-pl011.c
> +++ b/drivers/tty/serial/amba-pl011.c
> @@ -44,6 +44,7 @@
>
> #include "amba-pl011.h"
>
> +#define ISEMPTY 1
> #define UART_NR 14
>
> #define SERIAL_AMBA_MAJOR 204
> @@ -264,6 +265,7 @@ struct uart_amba_port {
> unsigned int fifosize; /* vendor-specific */
> unsigned int old_cr; /* state during shutdown */
> unsigned int fixed_baud; /* vendor-set fixed baud rate */
> + unsigned int cr;
> char type[12];
> #ifdef CONFIG_DMA_ENGINE
> /* DMA stuff */
> @@ -1284,6 +1286,8 @@ static inline bool pl011_dma_rx_running(struct uart_amba_port *uap)
> #define pl011_dma_flush_buffer NULL
> #endif
>
> +static unsigned int pl011_tx_empty(struct uart_port *port);
> +
> static void pl011_stop_tx(struct uart_port *port)
> {
> struct uart_amba_port *uap =
> @@ -1292,6 +1296,17 @@ static void pl011_stop_tx(struct uart_port *port)
> uap->im &= ~UART011_TXIM;
> pl011_write(uap->im, uap, REG_IMSC);
> pl011_dma_tx_stop(uap);
> + if (port->rs485.flags & SER_RS485_ENABLED) {
> + while(pl011_tx_empty(port) != ISEMPTY) ;
No busy loops that run forever please.
> +
> + uap->cr = pl011_read(uap, REG_CR);
> + if (port->rs485.flags & SER_RS485_RTS_AFTER_SEND) {
> + uap->cr |= UART011_CR_RTS;
> + } else {
> + uap->cr &= ~UART011_CR_RTS;
> + }
checkpatch did not complain about this? It should have.
thanks,
greg k-h
