Fall back to polling mode if no interrupt is configured because there
is no possibility to connect the interrupt pin.
If no interrupt pin is available the driver uses a delayed worker to
poll the state of interrupt status registers (IIR).
Signed-off-by: Andre Werner <andre.werner@xxxxxxxxxxxxxxxxxxxxx>
---
V2:
- Change warning for polling mode to debug log entry
- Correct typo: Resuse -> Reuse
- Format define with missing tabs for SC16IS7XX_POLL_PERIOD
- Format struct declaration sc16is7xx_one_config with missing tabs for polling and shutdown
- Adapt dtbinding with new polling feature
V3:
- Use suffix with units and drop a comment SC16IS7XX_POLL_PERIOD_MS. Sorry for that miss.
- Make Kernel lowercase.
V4:
- Reword commit messages for better understanding.
- Remove 'shutdown' property for canceling delayed worker.
- Rename worker function: sc16is7xx_transmission_poll -> sc16is7xx_poll_proc
- Unify argument for worker functions: kthread_work *work -> kthread_work *ws
V5:
- Replace of_property check with IRQ number check to set polling
property. This will add support for usage without device tree
definitions. Thanks for that advice.
- Add blank line es requested.
V6:
- Use polling mode for IRQ numbers <= 0 which encounter no valid IRQ
were found/defined.
V7:
- Try to improve and unify comments as requested.
- Fix typo in commit message: pull -> poll
---
drivers/tty/serial/sc16is7xx.c | 39 ++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index a3093e09309f..348ddc3103cd 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_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 +864,20 @@ 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 and set to zero.
+ */
+ sc16is7xx_irq(0, s);
+
+ 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 +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;
@@ -1211,6 +1229,10 @@ 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 +1254,9 @@ 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 +1563,11 @@ 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 <= 0);
+ 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 +1695,12 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype,
goto out_ports;
#endif
+ if (s->polling) {
+ /* Initialize a kthread work struct that is dedicated to 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 +1760,9 @@ 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);
--
2.48.0
