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Commit 78be70c8 authored by Jan Kundrát's avatar Jan Kundrát Committed by Greg Kroah-Hartman
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serial: max310x: Support IRQ sharing with other devices 

According to my chip's datasheet [1], the IRQ output is an open
collector pin which is suitable for sharing with other chips. The chip
also has a register which indicates which UART performed a change and
the driver checks that register already, so we have everything what is
needed to effectively share the IRQ GPIO.

[1] https://datasheets.maximintegrated.com/en/ds/MAX14830.pdf



Signed-off-by: default avatarJan Kundrát <jan.kundrat@cesnet.cz>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 80313586

drivers/tty/serial/max310x.c

+14 −6
Original line number Diff line number Diff line
@@ -685,9 +685,10 @@ static void max310x_handle_tx(struct uart_port *port) 
		uart_write_wakeup(port);

}



static void max310x_port_irq(struct max310x_port *s, int portno)

static irqreturn_t max310x_port_irq(struct max310x_port *s, int portno)

{

	struct uart_port *port = &s->p[portno].port;

	irqreturn_t res = IRQ_NONE;



	do {

		unsigned int ists, lsr, rxlen;
@@ -698,6 +699,8 @@ static void max310x_port_irq(struct max310x_port *s, int portno) 
		if (!ists && !rxlen)

			break;



		res = IRQ_HANDLED;



		if (ists & MAX310X_IRQ_CTS_BIT) {

			lsr = max310x_port_read(port, MAX310X_LSR_IRQSTS_REG);

			uart_handle_cts_change(port,
@@ -711,11 +714,13 @@ static void max310x_port_irq(struct max310x_port *s, int portno) 
			mutex_unlock(&s->mutex);

		}

	} while (1);

	return res;

}



static irqreturn_t max310x_ist(int irq, void *dev_id)

{

	struct max310x_port *s = (struct max310x_port *)dev_id;

	bool handled = false;



	if (s->devtype->nr > 1) {

		do {
@@ -726,12 +731,15 @@ static irqreturn_t max310x_ist(int irq, void *dev_id) 
			val = ((1 << s->devtype->nr) - 1) & ~val;

			if (!val)

				break;

			max310x_port_irq(s, fls(val) - 1);

			if (max310x_port_irq(s, fls(val) - 1) == IRQ_HANDLED)

				handled = true;

		} while (1);

	} else

		max310x_port_irq(s, 0);

	} else {

		if (max310x_port_irq(s, 0) == IRQ_HANDLED)

			handled = true;

	}



	return IRQ_HANDLED;

	return IRQ_RETVAL(handled);

}



static void max310x_wq_proc(struct work_struct *ws)
@@ -1239,7 +1247,7 @@ static int max310x_probe(struct device *dev, struct max310x_devtype *devtype, 


	/* Setup interrupt */

	ret = devm_request_threaded_irq(dev, irq, NULL, max310x_ist,

					IRQF_ONESHOT, dev_name(dev), s);

					IRQF_ONESHOT | IRQF_SHARED, dev_name(dev), s);

	if (!ret)

		return 0;