[PATCH] MEDIATEK: serial: 8250_mtk: Add ACPI support

Zhiyong Tao
2026-01-05T02:41:31Z

From: "Zhiyong.Tao" <zhiyong.tao@mediatek.com>

Add ACPI support to 8250_mtk driver. This makes it possible to
use UART on ARM-based desktops with EDK2 UEFI firmware.

Signed-off-by: Yenchia Chen <yenchia.chen@mediatek.com>
Signed-off-by: Zhiyong.Tao <zhiyong.tao@mediatek.com>
---
drivers/tty/serial/8250/8250_mtk.c | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
index 5875a7b9b4b1..e6a56cf54ae0 100644
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -19,6 +19,7 @@
#include <linux/dma-mapping.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
+#include <linux/units.h>

#include "8250.h"

@@ -521,6 +522,7 @@ static int mtk8250_probe(struct platform_device *pdev)
struct mtk8250_data *data;
struct resource *regs;
int irq, err;
+ struct fwnode_handle *fwnode = dev_fwnode(&pdev->dev);

irq = platform_get_irq(pdev, 0);
if (irq < 0)
@@ -543,12 +545,13 @@ static int mtk8250_probe(struct platform_device *pdev)

data->clk_count = 0;

- if (pdev->dev.of_node) {
+ if (is_of_node(fwnode)) {
err = mtk8250_probe_of(pdev, &uart.port, data);
if (err)
return err;
- } else
+ } else if (!fwnode) {
return -ENODEV;
+ }

spin_lock_init(&uart.port.lock);
uart.port.mapbase = regs->start;
@@ -564,14 +567,18 @@ static int mtk8250_probe(struct platform_device *pdev)
uart.port.startup = mtk8250_startup;
uart.port.set_termios = mtk8250_set_termios;
uart.port.uartclk = clk_get_rate(data->uart_clk);
+ if (!uart.port.uartclk)
+ uart.port.uartclk = 26 * HZ_PER_MHZ;
#ifdef CONFIG_SERIAL_8250_DMA
if (data->dma)
uart.dma = data->dma;
#endif

- /* Disable Rate Fix function */
- writel(0x0, uart.port.membase +
+ if (is_of_node(fwnode)) {
+ /* Disable Rate Fix function */
+ writel(0x0, uart.port.membase +
(MTK_UART_RATE_FIX << uart.port.regshift));
+ }

platform_set_drvdata(pdev, data);

@@ -649,11 +656,19 @@ static const struct of_device_id mtk8250_of_match[] = {
};
MODULE_DEVICE_TABLE(of, mtk8250_of_match);

+static const struct acpi_device_id mtk8250_acpi_match[] = {
+ { "MTKI0511" },
+ { "NVDA0240" },
+ {}
+};
+MODULE_DEVICE_TABLE(acpi, mtk8250_acpi_match);
+
static struct platform_driver mtk8250_platform_driver = {
.driver = {
.name = "mt6577-uart",
.pm = &mtk8250_pm_ops,
.of_match_table = mtk8250_of_match,
+ .acpi_match_table = mtk8250_acpi_match,
},
.probe = mtk8250_probe,
.remove = mtk8250_remove,
--
2.45.2