On 13 July 2017 at 05:33, Stefan Roese <s...@denx.de> wrote:
> Pasting longer lines into the U-Boot console prompt sometimes leads to
> characters missing. One problem here is the small 16-byte FIFO of the
> legacy NS16550 UART, e.g. on x86 platforms.
>
> This patch now introduces a Kconfig option to enable RX interrupt
> buffer support for NS16550 style UARTs. With this option enabled, I was
> able paste really long lines into the U-Boot console, without any
> characters missing.
>
> Signed-off-by: Stefan Roese <s...@denx.de>
> Cc: Simon Glass <s...@chromium.org>
> Cc: Bin Meng <bmeng...@gmail.com>
> ---
> drivers/serial/Kconfig | 10 +++++
> drivers/serial/ns16550.c | 106
> ++++++++++++++++++++++++++++++++++++++++++++---
> include/ns16550.h | 6 +++
> 3 files changed, 117 insertions(+), 5 deletions(-)
Reviewed-by: Simon Glass <s...@chromium.org>
nits below
>
> diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
> index b7dd2ac103..8284febae3 100644
> --- a/drivers/serial/Kconfig
> +++ b/drivers/serial/Kconfig
> @@ -64,6 +64,16 @@ config DM_SERIAL
> implements serial_putc() etc. The uclass interface is
> defined in include/serial.h.
>
> +config SERIAL_IRQ_BUFFER
> + bool "Enable RX interrupt buffer for serial input"
> + depends on DM_SERIAL
> + default n
> + help
> + Enable RX interrupt buffer support for the serial driver.
> + This enables pasting longer strings, even when the RX FIFO
> + of the UART is not big enough (e.g. 16 bytes on the normal
> + NS16550).
> +
> config SPL_DM_SERIAL
> bool "Enable Driver Model for serial drivers in SPL"
> depends on DM_SERIAL
> diff --git a/drivers/serial/ns16550.c b/drivers/serial/ns16550.c
> index e0e70244ce..686c088e1d 100644
> --- a/drivers/serial/ns16550.c
> +++ b/drivers/serial/ns16550.c
> @@ -315,6 +315,80 @@ DEBUG_UART_FUNCS
> #endif
>
> #ifdef CONFIG_DM_SERIAL
> +
> +#if CONFIG_IS_ENABLED(SERIAL_IRQ_BUFFER)
> +
> +#define BUF_COUNT 256
> +
> +static void rx_fifo_to_buf(struct udevice *dev)
> +{
> + struct NS16550 *const com_port = dev_get_priv(dev);
> + struct ns16550_platdata *plat = dev->platdata;
> +
> + /* Read all available chars into buffer */
> + while ((serial_in(&com_port->lsr) & UART_LSR_DR)) {
> + plat->buf[plat->wr_ptr++] = serial_in(&com_port->rbr);
> + plat->wr_ptr %= BUF_COUNT;
> + }
> +}
> +
> +static int rx_pending(struct udevice *dev)
> +{
> + struct ns16550_platdata *plat = dev->platdata;
> +
> + /*
> + * At startup it may happen, that some already received chars are
> + * "stuck" in the RX FIFO, even with the interrupt enabled. This
> + * RX FIFO flushing makes sure, that these chars are read out and
> + * the RX interrupts works as expected.
> + */
> + rx_fifo_to_buf(dev);
> +
> + return plat->rd_ptr != plat->wr_ptr ? 1 : 0;
> +}
> +
> +static int rx_get(struct udevice *dev)
> +{
> + struct ns16550_platdata *plat = dev->platdata;
> + char val;
> +
> + val = plat->buf[plat->rd_ptr++];
> + plat->rd_ptr %= BUF_COUNT;
> +
> + return val;
> +}
> +
> +void ns16550_handle_irq(void *data)
> +{
> + struct udevice *dev = (struct udevice *)data;
> + struct NS16550 *const com_port = dev_get_priv(dev);
> +
> + /* Check if interrupt is pending */
> + if (serial_in(&com_port->iir) & UART_IIR_NO_INT)
> + return;
> +
> + /* Flush all available characters from the RX FIFO into the RX buffer
> */
> + rx_fifo_to_buf(dev);
> +}
> +
> +#else /* CONFIG_SERIAL_IRQ_BUFFER */
> +
> +static int rx_pending(struct udevice *dev)
> +{
> + struct NS16550 *const com_port = dev_get_priv(dev);
> +
> + return serial_in(&com_port->lsr) & UART_LSR_DR ? 1 : 0;
> +}
> +
> +static int rx_get(struct udevice *dev)
> +{
> + struct NS16550 *const com_port = dev_get_priv(dev);
> +
> + return serial_in(&com_port->rbr);
> +}
> +
> +#endif /* CONFIG_SERIAL_IRQ_BUFFER */
> +
> static int ns16550_serial_putc(struct udevice *dev, const char ch)
> {
> struct NS16550 *const com_port = dev_get_priv(dev);
> @@ -340,19 +414,17 @@ static int ns16550_serial_pending(struct udevice *dev,
> bool input)
> struct NS16550 *const com_port = dev_get_priv(dev);
>
> if (input)
> - return serial_in(&com_port->lsr) & UART_LSR_DR ? 1 : 0;
> + return rx_pending(dev);
> else
> return serial_in(&com_port->lsr) & UART_LSR_THRE ? 0 : 1;
> }
>
> static int ns16550_serial_getc(struct udevice *dev)
> {
> - struct NS16550 *const com_port = dev_get_priv(dev);
> -
> - if (!(serial_in(&com_port->lsr) & UART_LSR_DR))
> + if (!ns16550_serial_pending(dev, true))
> return -EAGAIN;
>
> - return serial_in(&com_port->rbr);
> + return rx_get(dev);
> }
>
> static int ns16550_serial_setbrg(struct udevice *dev, int baudrate)
> @@ -375,6 +447,21 @@ int ns16550_serial_probe(struct udevice *dev)
> com_port->plat = dev_get_platdata(dev);
> NS16550_init(com_port, -1);
>
> +#if CONFIG_IS_ENABLED(SERIAL_IRQ_BUFFER)
> + if (gd->flags & GD_FLG_RELOC) {
> + struct ns16550_platdata *plat = dev->platdata;
> +
> + /* Allocate the RX buffer */
> + plat->buf = malloc(BUF_COUNT);
> +
> + /* Install the interrupt handler */
> + irq_install_handler(plat->irq, ns16550_handle_irq, dev);
Do we need to remove this in the remove() method?
> +
> + /* Enable RX interrupts */
> + serial_out(UART_IER_RDI, &com_port->ier);
> + }
> +#endif
> +
> return 0;
> }
>
> @@ -459,6 +546,15 @@ int ns16550_serial_ofdata_to_platdata(struct udevice
> *dev)
> if (port_type == PORT_JZ4780)
> plat->fcr |= UART_FCR_UME;
>
> +#if CONFIG_IS_ENABLED(SERIAL_IRQ_BUFFER)
> + plat->irq = fdtdec_get_int(gd->fdt_blob, dev_of_offset(dev),
> + "interrupts", 0);
> + if (!plat->irq) {
> + debug("ns16550 interrupt not provided\n");
> + return -EINVAL;
> + }
> +#endif
> +
> return 0;
> }
> #endif
> diff --git a/include/ns16550.h b/include/ns16550.h
> index 5fcbcd2e74..70d1ec8e6a 100644
> --- a/include/ns16550.h
> +++ b/include/ns16550.h
> @@ -58,6 +58,12 @@ struct ns16550_platdata {
> int clock;
> int reg_offset;
> u32 fcr;
> +
> + int irq;
> +
> + char *buf;
> + int rd_ptr;
> + int wr_ptr;
Please add comments to document these members.
> };
>
> struct udevice;
> --
> 2.13.3
>
Regards,
Simon
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