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serial: sc16is7xx: Add polling mode if no IRQ pin is available

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Fall back to polling mode if no interrupt is configured because there
is no possibility to connect the interrupt pin.
If "interrupts" property is missing in devicetree the driver
uses a delayed worker to pull the state of interrupt status registers.

Signed-off-by: Andre Werner <andre.werner@systec-electronic.com>
Link: https://lore.kernel.org/r/20250110073104.1029633-2-andre.werner@systec-electronic.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Andre Werner 2025-01-10 08:31:04 +01:00 • committed by Greg Kroah-Hartman
parent 4dd7c9d948
commit 104c1b9dde
1 changed files with 37 additions and 0 deletions
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37
drivers/tty/serial/sc16is7xx.c
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@ -314,6 +314,7 @@
#define SC16IS7XX_FIFO_SIZE (64)
#define SC16IS7XX_GPIOS_PER_BANK 4
#define SC16IS7XX_POLL_PERIOD_MS 10
#define SC16IS7XX_RECONF_MD BIT(0)
#define SC16IS7XX_RECONF_IER BIT(1)
#define SC16IS7XX_RECONF_RS485 BIT(2)
@ -348,6 +349,8 @@ struct sc16is7xx_port {
u8 mctrl_mask;
struct kthread_worker kworker;
struct task_struct *kworker_task;
struct kthread_delayed_work poll_work;
bool polling;
struct sc16is7xx_one p[];
};
@ -861,6 +864,18 @@ static irqreturn_t sc16is7xx_irq(int irq, void *dev_id)
return IRQ_HANDLED;
}
static void sc16is7xx_poll_proc(struct kthread_work *ws)
{
struct sc16is7xx_port *s = container_of(ws, struct sc16is7xx_port, poll_work.work);
/* Reuse standard IRQ handler. Interrupt ID is unused in this context. */
sc16is7xx_irq(0, s);
/* Setup delay based on SC16IS7XX_POLL_PERIOD_MS */
kthread_queue_delayed_work(&s->kworker, &s->poll_work,
msecs_to_jiffies(SC16IS7XX_POLL_PERIOD_MS));
}
static void sc16is7xx_tx_proc(struct kthread_work *ws)
{
struct uart_port *port = &(to_sc16is7xx_one(ws, tx_work)->port);
@ -1149,6 +1164,7 @@ 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;
@ -1211,6 +1227,10 @@ static int sc16is7xx_startup(struct uart_port *port)
sc16is7xx_enable_ms(port);
uart_port_unlock_irqrestore(port, flags);
if (s->polling)
kthread_queue_delayed_work(&s->kworker, &s->poll_work,
msecs_to_jiffies(SC16IS7XX_POLL_PERIOD_MS));
return 0;
}
@ -1232,6 +1252,9 @@ static void sc16is7xx_shutdown(struct uart_port *port)
sc16is7xx_power(port, 0);
if (s->polling)
kthread_cancel_delayed_work_sync(&s->poll_work);
kthread_flush_worker(&s->kworker);
}
@ -1538,6 +1561,11 @@ 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 = !!irq;
if (s->polling)
dev_dbg(dev,
"No interrupt pin definition, falling back to polling mode\n");
s->clk = devm_clk_get_optional(dev, NULL);
if (IS_ERR(s->clk))
return PTR_ERR(s->clk);
@ -1665,6 +1693,12 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype,
goto out_ports;
#endif
if (s->polling) {
/* Initialize kernel thread for polling */
kthread_init_delayed_work(&s->poll_work, sc16is7xx_poll_proc);
return 0;
}
/*
* Setup interrupt. We first try to acquire the IRQ line as level IRQ.
* If that succeeds, we can allow sharing the interrupt as well.
@ -1724,6 +1758,9 @@ void sc16is7xx_remove(struct device *dev)
sc16is7xx_power(&s->p[i].port, 0);
}
if (s->polling)
kthread_cancel_delayed_work_sync(&s->poll_work);
kthread_flush_worker(&s->kworker);
kthread_stop(s->kworker_task);