[PATCH] serial: 8250_pnp: Support configurable reg shift property

[GuanBing Huang]

From: albanhuang <albanhuang@xxxxxxxxxxx>

The 16550a serial port based on the ACPI table requires obtaining the
reg-shift attribute. In the ACPI scenario, If the reg-shift property
is not configured like in DTS, the 16550a serial driver cannot read or
write controller registers properly during initialization.

Signed-off-by: albanhuang <albanhuang@xxxxxxxxxxx>
Signed-off-by: tombinfan <tombinfan@xxxxxxxxxxx>
Signed-off-by: dylanlhdu <dylanlhdu@xxxxxxxxxxx>
---
 drivers/tty/serial/8250/8250_pnp.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/tty/serial/8250/8250_pnp.c b/drivers/tty/serial/8250/8250_pnp.c
index 1974bbadc975..25b4e41e9745 100644
--- a/drivers/tty/serial/8250/8250_pnp.c
+++ b/drivers/tty/serial/8250/8250_pnp.c
@@ -473,6 +473,7 @@ serial_pnp_probe(struct pnp_dev *dev, const struct pnp_device_id *dev_id)
 		uart.port.flags |= UPF_SHARE_IRQ;
 	uart.port.uartclk = 1843200;
 	device_property_read_u32(&dev->dev, "clock-frequency", &uart.port.uartclk);
+	device_property_read_u8(&dev->dev, "reg-shift", &uart.port.regshift);
 	uart.port.dev = &dev->dev;
 
 	line = serial8250_register_8250_port(&uart);
-- 
2.17.1