From: Tamseel Shams <redacted>

commit 8c6c378b0cbe0c9f1390986b5f8ffb5f6ff7593b upstream.

In few older Samsung SoCs like s3c2410, s3c2412
and s3c2440, UART IP is having 2 interrupt lines.
However, in other SoCs like s3c6400, s5pv210,
exynos5433, and exynos4210 UART is having only 1
interrupt line. Due to this, "platform_get_irq(platdev, 1)"
call in the driver gives the following false-positive error:
"IRQ index 1 not found" on newer SoC's.

This patch adds the condition to check for Tx interrupt
only for the those SoC's which have 2 interrupt lines.

Tested-by: Alim Akhtar <alim.akhtar@samsung.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: Tamseel Shams <redacted>
Cc: stable <redacted>
Link: https://lore.kernel.org/r/20200810030021.45348-1-m.shams@samsung.com (local)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/tty/serial/samsung.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c

@@ -1719,9 +1719,11 @@ static int s3c24xx_serial_init_port(stru
 		ourport->tx_irq = ret + 1;
 	}
 
-	ret = platform_get_irq(platdev, 1);
-	if (ret > 0)
-		ourport->tx_irq = ret;
+	if (!s3c24xx_serial_has_interrupt_mask(port)) {
+		ret = platform_get_irq(platdev, 1);
+		if (ret > 0)
+			ourport->tx_irq = ret;
+	}
 	/*
 	 * DMA is currently supported only on DT platforms, if DMA properties
 	 * are specified.