From 1543e317f1da31b75942316931e8f491a8920811 Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Thu, 04 Jan 2024 10:08:02 +0000
Subject: [PATCH] disable FB

---
 kernel/drivers/tty/serial/8250/8250_mtk.c |  475 +++++++++++++++++++++++++++++++++++++++++++++++++++++------
 1 files changed, 426 insertions(+), 49 deletions(-)

diff --git a/kernel/drivers/tty/serial/8250/8250_mtk.c b/kernel/drivers/tty/serial/8250/8250_mtk.c
index cc4f0c5..de48a58 100644
--- a/kernel/drivers/tty/serial/8250/8250_mtk.c
+++ b/kernel/drivers/tty/serial/8250/8250_mtk.c
@@ -10,31 +10,310 @@
 #include <linux/module.h>
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
+#include <linux/pinctrl/consumer.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/serial_8250.h>
 #include <linux/serial_reg.h>
+#include <linux/console.h>
+#include <linux/dma-mapping.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
 
 #include "8250.h"
 
-#define UART_MTK_HIGHS		0x09	/* Highspeed register */
-#define UART_MTK_SAMPLE_COUNT	0x0a	/* Sample count register */
-#define UART_MTK_SAMPLE_POINT	0x0b	/* Sample point register */
+#define MTK_UART_HIGHS		0x09	/* Highspeed register */
+#define MTK_UART_SAMPLE_COUNT	0x0a	/* Sample count register */
+#define MTK_UART_SAMPLE_POINT	0x0b	/* Sample point register */
 #define MTK_UART_RATE_FIX	0x0d	/* UART Rate Fix Register */
+#define MTK_UART_ESCAPE_DAT	0x10	/* Escape Character register */
+#define MTK_UART_ESCAPE_EN	0x11	/* Escape Enable register */
+#define MTK_UART_DMA_EN		0x13	/* DMA Enable register */
+#define MTK_UART_RXTRI_AD	0x14	/* RX Trigger address */
+#define MTK_UART_FRACDIV_L	0x15	/* Fractional divider LSB address */
+#define MTK_UART_FRACDIV_M	0x16	/* Fractional divider MSB address */
+#define MTK_UART_DEBUG0	0x18
+#define MTK_UART_IER_XOFFI	0x20	/* Enable XOFF character interrupt */
+#define MTK_UART_IER_RTSI	0x40	/* Enable RTS Modem status interrupt */
+#define MTK_UART_IER_CTSI	0x80	/* Enable CTS Modem status interrupt */
+
+#define MTK_UART_EFR		38	/* I/O: Extended Features Register */
+#define MTK_UART_EFR_EN		0x10	/* Enable enhancement feature */
+#define MTK_UART_EFR_RTS	0x40	/* Enable hardware rx flow control */
+#define MTK_UART_EFR_CTS	0x80	/* Enable hardware tx flow control */
+#define MTK_UART_EFR_NO_SW_FC	0x0	/* no sw flow control */
+#define MTK_UART_EFR_XON1_XOFF1	0xa	/* XON1/XOFF1 as sw flow control */
+#define MTK_UART_EFR_XON2_XOFF2	0x5	/* XON2/XOFF2 as sw flow control */
+#define MTK_UART_EFR_SW_FC_MASK	0xf	/* Enable CTS Modem status interrupt */
+#define MTK_UART_EFR_HW_FC	(MTK_UART_EFR_RTS | MTK_UART_EFR_CTS)
+#define MTK_UART_DMA_EN_TX	0x2
+#define MTK_UART_DMA_EN_RX	0x5
+
+#define MTK_UART_ESCAPE_CHAR	0x77	/* Escape char added under sw fc */
+#define MTK_UART_RX_SIZE	0x8000
+#define MTK_UART_TX_TRIGGER	1
+#define MTK_UART_RX_TRIGGER	MTK_UART_RX_SIZE
+
+#define MTK_UART_XON1		40	/* I/O: Xon character 1 */
+#define MTK_UART_XOFF1		42	/* I/O: Xoff character 1 */
+
+#ifdef CONFIG_SERIAL_8250_DMA
+enum dma_rx_status {
+	DMA_RX_START = 0,
+	DMA_RX_RUNNING = 1,
+	DMA_RX_SHUTDOWN = 2,
+};
+#endif
 
 struct mtk8250_data {
 	int			line;
+	unsigned int		rx_pos;
+	unsigned int		clk_count;
 	struct clk		*uart_clk;
 	struct clk		*bus_clk;
+	struct uart_8250_dma	*dma;
+#ifdef CONFIG_SERIAL_8250_DMA
+	enum dma_rx_status	rx_status;
+#endif
+	int			rx_wakeup_irq;
 };
+
+/* flow control mode */
+enum {
+	MTK_UART_FC_NONE,
+	MTK_UART_FC_SW,
+	MTK_UART_FC_HW,
+};
+
+#ifdef CONFIG_SERIAL_8250_DMA
+static void mtk8250_rx_dma(struct uart_8250_port *up);
+
+static void mtk8250_dma_rx_complete(void *param)
+{
+	struct uart_8250_port *up = param;
+	struct uart_8250_dma *dma = up->dma;
+	struct mtk8250_data *data = up->port.private_data;
+	struct tty_port *tty_port = &up->port.state->port;
+	struct dma_tx_state state;
+	int copied, total, cnt;
+	unsigned char *ptr;
+	unsigned long flags;
+
+	if (data->rx_status == DMA_RX_SHUTDOWN)
+		return;
+
+	spin_lock_irqsave(&up->port.lock, flags);
+
+	dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
+	total = dma->rx_size - state.residue;
+	cnt = total;
+
+	if ((data->rx_pos + cnt) > dma->rx_size)
+		cnt = dma->rx_size - data->rx_pos;
+
+	ptr = (unsigned char *)(data->rx_pos + dma->rx_buf);
+	copied = tty_insert_flip_string(tty_port, ptr, cnt);
+	data->rx_pos += cnt;
+
+	if (total > cnt) {
+		ptr = (unsigned char *)(dma->rx_buf);
+		cnt = total - cnt;
+		copied += tty_insert_flip_string(tty_port, ptr, cnt);
+		data->rx_pos = cnt;
+	}
+
+	up->port.icount.rx += copied;
+
+	tty_flip_buffer_push(tty_port);
+
+	mtk8250_rx_dma(up);
+
+	spin_unlock_irqrestore(&up->port.lock, flags);
+}
+
+static void mtk8250_rx_dma(struct uart_8250_port *up)
+{
+	struct uart_8250_dma *dma = up->dma;
+	struct dma_async_tx_descriptor	*desc;
+
+	desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr,
+					   dma->rx_size, DMA_DEV_TO_MEM,
+					   DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	if (!desc) {
+		pr_err("failed to prepare rx slave single\n");
+		return;
+	}
+
+	desc->callback = mtk8250_dma_rx_complete;
+	desc->callback_param = up;
+
+	dma->rx_cookie = dmaengine_submit(desc);
+
+	dma_async_issue_pending(dma->rxchan);
+}
+
+static void mtk8250_dma_enable(struct uart_8250_port *up)
+{
+	struct uart_8250_dma *dma = up->dma;
+	struct mtk8250_data *data = up->port.private_data;
+	int lcr = serial_in(up, UART_LCR);
+
+	if (data->rx_status != DMA_RX_START)
+		return;
+
+	dma->rxconf.src_port_window_size	= dma->rx_size;
+	dma->rxconf.src_addr				= dma->rx_addr;
+
+	dma->txconf.dst_port_window_size	= UART_XMIT_SIZE;
+	dma->txconf.dst_addr				= dma->tx_addr;
+
+	serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_RCVR |
+		UART_FCR_CLEAR_XMIT);
+	serial_out(up, MTK_UART_DMA_EN,
+		   MTK_UART_DMA_EN_RX | MTK_UART_DMA_EN_TX);
+
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+	serial_out(up, MTK_UART_EFR, UART_EFR_ECB);
+	serial_out(up, UART_LCR, lcr);
+
+	if (dmaengine_slave_config(dma->rxchan, &dma->rxconf) != 0)
+		pr_err("failed to configure rx dma channel\n");
+	if (dmaengine_slave_config(dma->txchan, &dma->txconf) != 0)
+		pr_err("failed to configure tx dma channel\n");
+
+	data->rx_status = DMA_RX_RUNNING;
+	data->rx_pos = 0;
+	mtk8250_rx_dma(up);
+}
+#endif
+
+static int mtk8250_startup(struct uart_port *port)
+{
+#ifdef CONFIG_SERIAL_8250_DMA
+	struct uart_8250_port *up = up_to_u8250p(port);
+	struct mtk8250_data *data = port->private_data;
+
+	/* disable DMA for console */
+	if (uart_console(port))
+		up->dma = NULL;
+
+	if (up->dma) {
+		data->rx_status = DMA_RX_START;
+		uart_circ_clear(&port->state->xmit);
+	}
+#endif
+	memset(&port->icount, 0, sizeof(port->icount));
+
+	return serial8250_do_startup(port);
+}
+
+static void mtk8250_shutdown(struct uart_port *port)
+{
+#ifdef CONFIG_SERIAL_8250_DMA
+	struct uart_8250_port *up = up_to_u8250p(port);
+	struct mtk8250_data *data = port->private_data;
+
+	if (up->dma)
+		data->rx_status = DMA_RX_SHUTDOWN;
+#endif
+
+	return serial8250_do_shutdown(port);
+}
+
+static void mtk8250_disable_intrs(struct uart_8250_port *up, int mask)
+{
+	serial_out(up, UART_IER, serial_in(up, UART_IER) & (~mask));
+}
+
+static void mtk8250_enable_intrs(struct uart_8250_port *up, int mask)
+{
+	serial_out(up, UART_IER, serial_in(up, UART_IER) | mask);
+}
+
+static void mtk8250_set_flow_ctrl(struct uart_8250_port *up, int mode)
+{
+	struct uart_port *port = &up->port;
+	int lcr = serial_in(up, UART_LCR);
+
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+	serial_out(up, MTK_UART_EFR, UART_EFR_ECB);
+	serial_out(up, UART_LCR, lcr);
+	lcr = serial_in(up, UART_LCR);
+
+	switch (mode) {
+	case MTK_UART_FC_NONE:
+		serial_out(up, MTK_UART_ESCAPE_DAT, MTK_UART_ESCAPE_CHAR);
+		serial_out(up, MTK_UART_ESCAPE_EN, 0x00);
+		serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+		serial_out(up, MTK_UART_EFR, serial_in(up, MTK_UART_EFR) &
+			(~(MTK_UART_EFR_HW_FC | MTK_UART_EFR_SW_FC_MASK)));
+		serial_out(up, UART_LCR, lcr);
+		mtk8250_disable_intrs(up, MTK_UART_IER_XOFFI |
+			MTK_UART_IER_RTSI | MTK_UART_IER_CTSI);
+		break;
+
+	case MTK_UART_FC_HW:
+		serial_out(up, MTK_UART_ESCAPE_DAT, MTK_UART_ESCAPE_CHAR);
+		serial_out(up, MTK_UART_ESCAPE_EN, 0x00);
+		serial_out(up, UART_MCR, UART_MCR_RTS);
+		serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+
+		/*enable hw flow control*/
+		serial_out(up, MTK_UART_EFR, MTK_UART_EFR_HW_FC |
+			(serial_in(up, MTK_UART_EFR) &
+			(~(MTK_UART_EFR_HW_FC | MTK_UART_EFR_SW_FC_MASK))));
+
+		serial_out(up, UART_LCR, lcr);
+		mtk8250_disable_intrs(up, MTK_UART_IER_XOFFI);
+		mtk8250_enable_intrs(up, MTK_UART_IER_CTSI | MTK_UART_IER_RTSI);
+		break;
+
+	case MTK_UART_FC_SW:	/*MTK software flow control */
+		serial_out(up, MTK_UART_ESCAPE_DAT, MTK_UART_ESCAPE_CHAR);
+		serial_out(up, MTK_UART_ESCAPE_EN, 0x01);
+		serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+
+		/*enable sw flow control */
+		serial_out(up, MTK_UART_EFR, MTK_UART_EFR_XON1_XOFF1 |
+			(serial_in(up, MTK_UART_EFR) &
+			(~(MTK_UART_EFR_HW_FC | MTK_UART_EFR_SW_FC_MASK))));
+
+		serial_out(up, MTK_UART_XON1, START_CHAR(port->state->port.tty));
+		serial_out(up, MTK_UART_XOFF1, STOP_CHAR(port->state->port.tty));
+		serial_out(up, UART_LCR, lcr);
+		mtk8250_disable_intrs(up, MTK_UART_IER_CTSI|MTK_UART_IER_RTSI);
+		mtk8250_enable_intrs(up, MTK_UART_IER_XOFFI);
+		break;
+	default:
+		break;
+	}
+}
 
 static void
 mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
 			struct ktermios *old)
 {
+	unsigned short fraction_L_mapping[] = {
+		0, 1, 0x5, 0x15, 0x55, 0x57, 0x57, 0x77, 0x7F, 0xFF, 0xFF
+	};
+	unsigned short fraction_M_mapping[] = {
+		0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 3
+	};
 	struct uart_8250_port *up = up_to_u8250p(port);
+	unsigned int baud, quot, fraction;
 	unsigned long flags;
-	unsigned int baud, quot;
+	int mode;
+
+#ifdef CONFIG_SERIAL_8250_DMA
+	if (up->dma) {
+		if (uart_console(port)) {
+			devm_kfree(up->port.dev, up->dma);
+			up->dma = NULL;
+		} else {
+			mtk8250_dma_enable(up);
+		}
+	}
+#endif
 
 	/*
 	 * Store the requested baud rate before calling the generic 8250
@@ -52,7 +331,7 @@
 	tty_termios_encode_baud_rate(termios, baud, baud);
 
 	/*
-	 * Mediatek UARTs use an extra highspeed register (UART_MTK_HIGHS)
+	 * Mediatek UARTs use an extra highspeed register (MTK_UART_HIGHS)
 	 *
 	 * We need to recalcualte the quot register, as the claculation depends
 	 * on the vaule in the highspeed register.
@@ -68,18 +347,11 @@
 				  port->uartclk / 16 / UART_DIV_MAX,
 				  port->uartclk);
 
-	if (baud <= 115200) {
-		serial_port_out(port, UART_MTK_HIGHS, 0x0);
+	if (baud < 115200) {
+		serial_port_out(port, MTK_UART_HIGHS, 0x0);
 		quot = uart_get_divisor(port, baud);
-	} else if (baud <= 576000) {
-		serial_port_out(port, UART_MTK_HIGHS, 0x2);
-
-		/* Set to next lower baudrate supported */
-		if ((baud == 500000) || (baud == 576000))
-			baud = 460800;
-		quot = DIV_ROUND_UP(port->uartclk, 4 * baud);
 	} else {
-		serial_port_out(port, UART_MTK_HIGHS, 0x3);
+		serial_port_out(port, MTK_UART_HIGHS, 0x3);
 		quot = DIV_ROUND_UP(port->uartclk, 256 * baud);
 	}
 
@@ -101,17 +373,39 @@
 	/* reset DLAB */
 	serial_port_out(port, UART_LCR, up->lcr);
 
-	if (baud > 460800) {
+	if (baud >= 115200) {
 		unsigned int tmp;
 
-		tmp = DIV_ROUND_CLOSEST(port->uartclk, quot * baud);
-		serial_port_out(port, UART_MTK_SAMPLE_COUNT, tmp - 1);
-		serial_port_out(port, UART_MTK_SAMPLE_POINT,
-					(tmp - 2) >> 1);
+		tmp = (port->uartclk / (baud *  quot)) - 1;
+		serial_port_out(port, MTK_UART_SAMPLE_COUNT, tmp);
+		serial_port_out(port, MTK_UART_SAMPLE_POINT,
+					(tmp >> 1) - 1);
+
+		/*count fraction to set fractoin register */
+		fraction = ((port->uartclk  * 100) / baud / quot) % 100;
+		fraction = DIV_ROUND_CLOSEST(fraction, 10);
+		serial_port_out(port, MTK_UART_FRACDIV_L,
+						fraction_L_mapping[fraction]);
+		serial_port_out(port, MTK_UART_FRACDIV_M,
+						fraction_M_mapping[fraction]);
 	} else {
-		serial_port_out(port, UART_MTK_SAMPLE_COUNT, 0x00);
-		serial_port_out(port, UART_MTK_SAMPLE_POINT, 0xff);
+		serial_port_out(port, MTK_UART_SAMPLE_COUNT, 0x00);
+		serial_port_out(port, MTK_UART_SAMPLE_POINT, 0xff);
+		serial_port_out(port, MTK_UART_FRACDIV_L, 0x00);
+		serial_port_out(port, MTK_UART_FRACDIV_M, 0x00);
 	}
+
+	if ((termios->c_cflag & CRTSCTS) && (!(termios->c_iflag & CRTSCTS)))
+		mode = MTK_UART_FC_HW;
+	else if (termios->c_iflag & CRTSCTS)
+		mode = MTK_UART_FC_SW;
+	else
+		mode = MTK_UART_FC_NONE;
+
+	mtk8250_set_flow_ctrl(up, mode);
+
+	if (uart_console(port))
+		up->port.cons->cflag = termios->c_cflag;
 
 	spin_unlock_irqrestore(&port->lock, flags);
 	/* Don't rewrite B0 */
@@ -122,9 +416,18 @@
 static int __maybe_unused mtk8250_runtime_suspend(struct device *dev)
 {
 	struct mtk8250_data *data = dev_get_drvdata(dev);
+	struct uart_8250_port *up = serial8250_get_port(data->line);
 
-	clk_disable_unprepare(data->uart_clk);
-	clk_disable_unprepare(data->bus_clk);
+	/* wait until UART in idle status */
+	while
+		(serial_in(up, MTK_UART_DEBUG0));
+
+	if (data->clk_count == 0U) {
+		dev_dbg(dev, "%s clock count is 0\n", __func__);
+	} else {
+		clk_disable_unprepare(data->bus_clk);
+		data->clk_count--;
+	}
 
 	return 0;
 }
@@ -134,16 +437,16 @@
 	struct mtk8250_data *data = dev_get_drvdata(dev);
 	int err;
 
-	err = clk_prepare_enable(data->uart_clk);
-	if (err) {
-		dev_warn(dev, "Can't enable clock\n");
-		return err;
-	}
-
-	err = clk_prepare_enable(data->bus_clk);
-	if (err) {
-		dev_warn(dev, "Can't enable bus clock\n");
-		return err;
+	if (data->clk_count > 0U) {
+		dev_dbg(dev, "%s clock count is %d\n", __func__,
+			data->clk_count);
+	} else {
+		err = clk_prepare_enable(data->bus_clk);
+		if (err) {
+			dev_warn(dev, "Can't enable bus clock\n");
+			return err;
+		}
+		data->clk_count++;
 	}
 
 	return 0;
@@ -153,17 +456,30 @@
 mtk8250_do_pm(struct uart_port *port, unsigned int state, unsigned int old)
 {
 	if (!state)
-		pm_runtime_get_sync(port->dev);
+		if (!mtk8250_runtime_resume(port->dev))
+			pm_runtime_get_sync(port->dev);
 
 	serial8250_do_pm(port, state, old);
 
 	if (state)
-		pm_runtime_put_sync_suspend(port->dev);
+		if (!pm_runtime_put_sync_suspend(port->dev))
+			mtk8250_runtime_suspend(port->dev);
 }
+
+#ifdef CONFIG_SERIAL_8250_DMA
+static bool mtk8250_dma_filter(struct dma_chan *chan, void *param)
+{
+	return false;
+}
+#endif
 
 static int mtk8250_probe_of(struct platform_device *pdev, struct uart_port *p,
 			   struct mtk8250_data *data)
 {
+#ifdef CONFIG_SERIAL_8250_DMA
+	int dmacnt;
+#endif
+
 	data->uart_clk = devm_clk_get(&pdev->dev, "baud");
 	if (IS_ERR(data->uart_clk)) {
 		/*
@@ -180,19 +496,42 @@
 	}
 
 	data->bus_clk = devm_clk_get(&pdev->dev, "bus");
-	return PTR_ERR_OR_ZERO(data->bus_clk);
+	if (IS_ERR(data->bus_clk))
+		return PTR_ERR(data->bus_clk);
+
+	data->dma = NULL;
+#ifdef CONFIG_SERIAL_8250_DMA
+	dmacnt = of_property_count_strings(pdev->dev.of_node, "dma-names");
+	if (dmacnt == 2) {
+		data->dma = devm_kzalloc(&pdev->dev, sizeof(*data->dma),
+					 GFP_KERNEL);
+		if (!data->dma)
+			return -ENOMEM;
+
+		data->dma->fn = mtk8250_dma_filter;
+		data->dma->rx_size = MTK_UART_RX_SIZE;
+		data->dma->rxconf.src_maxburst = MTK_UART_RX_TRIGGER;
+		data->dma->txconf.dst_maxburst = MTK_UART_TX_TRIGGER;
+	}
+#endif
+
+	return 0;
 }
 
 static int mtk8250_probe(struct platform_device *pdev)
 {
 	struct uart_8250_port uart = {};
-	struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 	struct mtk8250_data *data;
-	int err;
+	struct resource *regs;
+	int irq, err;
 
-	if (!regs || !irq) {
-		dev_err(&pdev->dev, "no registers/irq defined\n");
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!regs) {
+		dev_err(&pdev->dev, "no registers defined\n");
 		return -EINVAL;
 	}
 
@@ -205,6 +544,8 @@
 	if (!data)
 		return -ENOMEM;
 
+	data->clk_count = 0;
+
 	if (pdev->dev.of_node) {
 		err = mtk8250_probe_of(pdev, &uart.port, data);
 		if (err)
@@ -214,7 +555,7 @@
 
 	spin_lock_init(&uart.port.lock);
 	uart.port.mapbase = regs->start;
-	uart.port.irq = irq->start;
+	uart.port.irq = irq;
 	uart.port.pm = mtk8250_do_pm;
 	uart.port.type = PORT_16550;
 	uart.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT;
@@ -222,8 +563,14 @@
 	uart.port.iotype = UPIO_MEM32;
 	uart.port.regshift = 2;
 	uart.port.private_data = data;
+	uart.port.shutdown = mtk8250_shutdown;
+	uart.port.startup = mtk8250_startup;
 	uart.port.set_termios = mtk8250_set_termios;
 	uart.port.uartclk = clk_get_rate(data->uart_clk);
+#ifdef CONFIG_SERIAL_8250_DMA
+	if (data->dma)
+		uart.dma = data->dma;
+#endif
 
 	/* Disable Rate Fix function */
 	writel(0x0, uart.port.membase +
@@ -231,18 +578,25 @@
 
 	platform_set_drvdata(pdev, data);
 
+	pm_runtime_enable(&pdev->dev);
 	err = mtk8250_runtime_resume(&pdev->dev);
 	if (err)
-		return err;
+		goto err_pm_disable;
 
 	data->line = serial8250_register_8250_port(&uart);
-	if (data->line < 0)
-		return data->line;
+	if (data->line < 0) {
+		err = data->line;
+		goto err_pm_disable;
+	}
 
-	pm_runtime_set_active(&pdev->dev);
-	pm_runtime_enable(&pdev->dev);
+	data->rx_wakeup_irq = platform_get_irq_optional(pdev, 1);
 
 	return 0;
+
+err_pm_disable:
+	pm_runtime_disable(&pdev->dev);
+
+	return err;
 }
 
 static int mtk8250_remove(struct platform_device *pdev)
@@ -252,10 +606,12 @@
 	pm_runtime_get_sync(&pdev->dev);
 
 	serial8250_unregister_port(data->line);
-	mtk8250_runtime_suspend(&pdev->dev);
 
 	pm_runtime_disable(&pdev->dev);
 	pm_runtime_put_noidle(&pdev->dev);
+
+	if (!pm_runtime_status_suspended(&pdev->dev))
+		mtk8250_runtime_suspend(&pdev->dev);
 
 	return 0;
 }
@@ -263,8 +619,23 @@
 static int __maybe_unused mtk8250_suspend(struct device *dev)
 {
 	struct mtk8250_data *data = dev_get_drvdata(dev);
+	int irq = data->rx_wakeup_irq;
+	int err;
 
 	serial8250_suspend_port(data->line);
+
+	pinctrl_pm_select_sleep_state(dev);
+	if (irq >= 0) {
+		err = enable_irq_wake(irq);
+		if (err) {
+			dev_err(dev,
+				"failed to enable irq wake on IRQ %d: %d\n",
+				irq, err);
+			pinctrl_pm_select_default_state(dev);
+			serial8250_resume_port(data->line);
+			return err;
+		}
+	}
 
 	return 0;
 }
@@ -272,6 +643,11 @@
 static int __maybe_unused mtk8250_resume(struct device *dev)
 {
 	struct mtk8250_data *data = dev_get_drvdata(dev);
+	int irq = data->rx_wakeup_irq;
+
+	if (irq >= 0)
+		disable_irq_wake(irq);
+	pinctrl_pm_select_default_state(dev);
 
 	serial8250_resume_port(data->line);
 
@@ -309,6 +685,7 @@
 		return -ENODEV;
 
 	device->port.iotype = UPIO_MEM32;
+	device->port.regshift = 2;
 
 	return early_serial8250_setup(device, NULL);
 }

--
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