On Thu, Dec 19, 2024 at 09:46:38AM +0100, Andre Werner wrote:
> Fall back to polling mode if no interrupt is configured because not
> possible. If "interrupts" property is missing in devicetree the driver
> uses a delayed worker to pull state of interrupt status registers.
>
> Signed-off-by: Andre Werner <andre.werner@xxxxxxxxxxxxxxxxxxxxx>
> ---
> This driver was tested on Linux 5.10. We had a custom board that was not
> able to connect the interrupt port. Only I2C was available.
Could you not test this on the latest tree? 5.10 is _VERY_ old now.
> ---
> ---
> drivers/tty/serial/sc16is7xx.c | 40 ++++++++++++++++++++++++++++++++++
> 1 file changed, 40 insertions(+)
>
> diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
> index a3093e09309f..31962fdca178 100644
> --- a/drivers/tty/serial/sc16is7xx.c
> +++ b/drivers/tty/serial/sc16is7xx.c
> @@ -314,6 +314,7 @@
> #define SC16IS7XX_FIFO_SIZE (64)
> #define SC16IS7XX_GPIOS_PER_BANK 4
>
> +#define SC16IS7XX_POLL_PERIOD 10 /*ms*/
Please use a tab here.
> #define SC16IS7XX_RECONF_MD BIT(0)
> #define SC16IS7XX_RECONF_IER BIT(1)
> #define SC16IS7XX_RECONF_RS485 BIT(2)
> @@ -348,6 +349,9 @@ struct sc16is7xx_port {
> u8 mctrl_mask;
> struct kthread_worker kworker;
> struct task_struct *kworker_task;
> + struct kthread_delayed_work poll_work;
> + bool polling;
> + bool shutdown;
> struct sc16is7xx_one p[];
> };
>
> @@ -861,6 +865,19 @@ static irqreturn_t sc16is7xx_irq(int irq, void *dev_id)
> return IRQ_HANDLED;
> }
>
> +static void sc16is7xx_transmission_poll(struct kthread_work *work)
> +{
> + struct sc16is7xx_port *s = container_of(work, struct sc16is7xx_port, poll_work.work);
> +
> + /* Resuse standard IRQ handler. Interrupt ID is unused in this context. */
> + sc16is7xx_irq(0, s);
> +
> + /* setup delay based on SC16IS7XX_POLL_PERIOD */
> + if (!s->shutdown)
> + kthread_queue_delayed_work(&s->kworker, &s->poll_work,
> + msecs_to_jiffies(SC16IS7XX_POLL_PERIOD));
> +}
> +
> static void sc16is7xx_tx_proc(struct kthread_work *ws)
> {
> struct uart_port *port = &(to_sc16is7xx_one(ws, tx_work)->port);
> @@ -1149,6 +1166,7 @@ static int sc16is7xx_config_rs485(struct uart_port *port, struct ktermios *termi
> static int sc16is7xx_startup(struct uart_port *port)
> {
> struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
> + struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
> unsigned int val;
> unsigned long flags;
>
> @@ -1210,6 +1228,11 @@ static int sc16is7xx_startup(struct uart_port *port)
> uart_port_lock_irqsave(port, &flags);
> sc16is7xx_enable_ms(port);
> uart_port_unlock_irqrestore(port, flags);
> + if (s->polling) {
> + s->shutdown = false;
> + kthread_queue_delayed_work(&s->kworker, &s->poll_work,
> + msecs_to_jiffies(SC16IS7XX_POLL_PERIOD));
> + }
>
> return 0;
> }
> @@ -1232,6 +1255,10 @@ static void sc16is7xx_shutdown(struct uart_port *port)
>
> sc16is7xx_power(port, 0);
>
> + if (s->polling) {
> + s->shutdown = true;
> + kthread_cancel_delayed_work_sync(&s->poll_work);
> + }
> kthread_flush_worker(&s->kworker);
> }
>
> @@ -1537,7 +1564,13 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype,
>
> /* Always ask for fixed clock rate from a property. */
> device_property_read_u32(dev, "clock-frequency", &uartclk);
> + s->polling = !device_property_present(dev, "interrupts");
>
> + if (s->polling) {
> + dev_warn(dev,
> + "No interrupt definition found. Falling back to polling mode.\n");
What is a user supposed to do with this message? And why would a device
NOT have any interrupts? This feels like it is just going to pound on
the device and cause a lot of power drain for just a simple little uart.
Why can't your system provide a valid irq line?
thanks,
greg k-h
