diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index 8caecfc85d93..77fe0588fd6b 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -175,7 +175,9 @@ static unsigned int __maybe_unused serial_icr_read(struct uart_8250_port *up,
 	return value;
 }
 
+void serial8250_clear_fifos(struct uart_8250_port *p);
 void serial8250_clear_and_reinit_fifos(struct uart_8250_port *p);
+void serial8250_fifo_wait_for_lsr_thre(struct uart_8250_port *up, unsigned int count);
 
 void serial8250_rpm_get(struct uart_8250_port *p);
 void serial8250_rpm_put(struct uart_8250_port *p);
@@ -400,6 +402,26 @@ static inline bool serial8250_tx_dma_running(struct uart_8250_port *p)
 
 	return dma && dma->tx_running;
 }
+
+static inline void serial8250_tx_dma_pause(struct uart_8250_port *p)
+{
+	struct uart_8250_dma *dma = p->dma;
+
+	if (!dma->tx_running)
+		return;
+
+	dmaengine_pause(dma->txchan);
+}
+
+static inline void serial8250_tx_dma_resume(struct uart_8250_port *p)
+{
+	struct uart_8250_dma *dma = p->dma;
+
+	if (!dma->tx_running)
+		return;
+
+	dmaengine_resume(dma->txchan);
+}
 #else
 static inline int serial8250_tx_dma(struct uart_8250_port *p)
 {
@@ -421,6 +443,9 @@ static inline bool serial8250_tx_dma_running(struct uart_8250_port *p)
 {
 	return false;
 }
+
+static inline void serial8250_tx_dma_pause(struct uart_8250_port *p) { }
+static inline void serial8250_tx_dma_resume(struct uart_8250_port *p) { }
 #endif
 
 static inline int ns16550a_goto_highspeed(struct uart_8250_port *up)
diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c
index bdd26c9f34bd..3b6452e759d5 100644
--- a/drivers/tty/serial/8250/8250_dma.c
+++ b/drivers/tty/serial/8250/8250_dma.c
@@ -162,7 +162,22 @@ void serial8250_tx_dma_flush(struct uart_8250_port *p)
 	 */
 	dma->tx_size = 0;
 
+	/*
+	 * We can't use `dmaengine_terminate_sync` because `uart_flush_buffer` is
+	 * holding the uart port spinlock.
+	 */
 	dmaengine_terminate_async(dma->txchan);
+
+	/*
+	 * The callback might or might not run. If it doesn't run, we need to ensure
+	 * that `tx_running` is cleared so that we can schedule new transactions.
+	 * If it does run, then the zombie callback will clear `tx_running` again
+	 * and perform a no-op since `tx_size` was cleared above.
+	 *
+	 * In either case, we ASSUME the DMA transaction will terminate before we
+	 * issue a new `serial8250_tx_dma`.
+	 */
+	dma->tx_running = 0;
 }
 
 int serial8250_rx_dma(struct uart_8250_port *p)
diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index db73b2ae17fa..94beadb4024d 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -9,10 +9,14 @@
  * LCR is written whilst busy.  If it is, then a busy detect interrupt is
  * raised, the LCR needs to be rewritten and the uart status register read.
  */
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/cleanup.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/io.h>
+#include <linux/lockdep.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/notifier.h>
@@ -40,8 +44,12 @@
 #define RZN1_UART_RDMACR 0x110 /* DMA Control Register Receive Mode */
 
 /* DesignWare specific register fields */
+#define DW_UART_IIR_IID			GENMASK(3, 0)
+
 #define DW_UART_MCR_SIRE		BIT(6)
 
+#define DW_UART_USR_BUSY		BIT(0)
+
 /* Renesas specific register fields */
 #define RZN1_UART_xDMACR_DMA_EN		BIT(0)
 #define RZN1_UART_xDMACR_1_WORD_BURST	(0 << 1)
@@ -56,6 +64,13 @@
 #define DW_UART_QUIRK_IS_DMA_FC		BIT(3)
 #define DW_UART_QUIRK_APMC0D08		BIT(4)
 #define DW_UART_QUIRK_CPR_VALUE		BIT(5)
+#define DW_UART_QUIRK_IER_KICK		BIT(6)
+
+/*
+ * Number of consecutive IIR_NO_INT interrupts required to trigger interrupt
+ * storm prevention code.
+ */
+#define DW_UART_QUIRK_IER_KICK_THRES	4
 
 struct dw8250_platform_data {
 	u8 usr_reg;
@@ -77,6 +92,9 @@ struct dw8250_data {
 
 	unsigned int		skip_autocfg:1;
 	unsigned int		uart_16550_compatible:1;
+	unsigned int		in_idle:1;
+
+	u8			no_int_count;
 };
 
 static inline struct dw8250_data *to_dw8250_data(struct dw8250_port_data *data)
@@ -107,78 +125,167 @@ static inline u32 dw8250_modify_msr(struct uart_port *p, unsigned int offset, u3
 	return value;
 }
 
-/*
- * This function is being called as part of the uart_port::serial_out()
- * routine. Hence, it must not call serial_port_out() or serial_out()
- * against the modified registers here, i.e. LCR.
- */
-static void dw8250_force_idle(struct uart_port *p)
+static void dw8250_idle_exit(struct uart_port *p)
 {
+	struct dw8250_data *d = to_dw8250_data(p->private_data);
 	struct uart_8250_port *up = up_to_u8250p(p);
-	unsigned int lsr;
 
-	/*
-	 * The following call currently performs serial_out()
-	 * against the FCR register. Because it differs to LCR
-	 * there will be no infinite loop, but if it ever gets
-	 * modified, we might need a new custom version of it
-	 * that avoids infinite recursion.
-	 */
-	serial8250_clear_and_reinit_fifos(up);
+	if (d->uart_16550_compatible)
+		return;
 
-	/*
-	 * With PSLVERR_RESP_EN parameter set to 1, the device generates an
-	 * error response when an attempt to read an empty RBR with FIFO
-	 * enabled.
-	 */
-	if (up->fcr & UART_FCR_ENABLE_FIFO) {
-		lsr = serial_port_in(p, UART_LSR);
-		if (!(lsr & UART_LSR_DR))
-			return;
+	if (up->capabilities & UART_CAP_FIFO)
+		serial_port_out(p, UART_FCR, up->fcr);
+	serial_port_out(p, UART_MCR, up->mcr);
+	serial_port_out(p, UART_IER, up->ier);
+
+	/* DMA Rx is restarted by IRQ handler as needed. */
+	if (up->dma)
+		serial8250_tx_dma_resume(up);
+
+	d->in_idle = 0;
+}
+
+/*
+ * Ensure BUSY is not asserted. If DW UART is configured with
+ * !uart_16550_compatible, the writes to LCR, DLL, and DLH fail while
+ * BUSY is asserted.
+ *
+ * Context: port's lock must be held
+ */
+static int dw8250_idle_enter(struct uart_port *p)
+{
+	struct dw8250_data *d = to_dw8250_data(p->private_data);
+	unsigned int usr_reg = d->pdata ? d->pdata->usr_reg : DW_UART_USR;
+	struct uart_8250_port *up = up_to_u8250p(p);
+	int retries;
+	u32 lsr;
+
+	lockdep_assert_held_once(&p->lock);
+
+	if (d->uart_16550_compatible)
+		return 0;
+
+	d->in_idle = 1;
+
+	/* Prevent triggering interrupt from RBR filling */
+	serial_port_out(p, UART_IER, 0);
+
+	if (up->dma) {
+		serial8250_rx_dma_flush(up);
+		if (serial8250_tx_dma_running(up))
+			serial8250_tx_dma_pause(up);
 	}
 
-	serial_port_in(p, UART_RX);
+	/*
+	 * Wait until Tx becomes empty + one extra frame time to ensure all bits
+	 * have been sent on the wire.
+	 *
+	 * FIXME: frame_time delay is too long with very low baudrates.
+	 */
+	serial8250_fifo_wait_for_lsr_thre(up, p->fifosize);
+	ndelay(p->frame_time);
+
+	serial_port_out(p, UART_MCR, up->mcr | UART_MCR_LOOP);
+
+	retries = 4;	/* Arbitrary limit, 2 was always enough in tests */
+	do {
+		serial8250_clear_fifos(up);
+		if (!(serial_port_in(p, usr_reg) & DW_UART_USR_BUSY))
+			break;
+		/* FIXME: frame_time delay is too long with very low baudrates. */
+		ndelay(p->frame_time);
+	} while (--retries);
+
+	lsr = serial_lsr_in(up);
+	if (lsr & UART_LSR_DR) {
+		serial_port_in(p, UART_RX);
+		up->lsr_saved_flags = 0;
+	}
+
+	/* Now guaranteed to have BUSY deasserted? Just sanity check */
+	if (serial_port_in(p, usr_reg) & DW_UART_USR_BUSY) {
+		dw8250_idle_exit(p);
+		return -EBUSY;
+	}
+
+	return 0;
+}
+
+static void dw8250_set_divisor(struct uart_port *p, unsigned int baud,
+			       unsigned int quot, unsigned int quot_frac)
+{
+	struct uart_8250_port *up = up_to_u8250p(p);
+	int ret;
+
+	ret = dw8250_idle_enter(p);
+	if (ret < 0)
+		return;
+
+	serial_port_out(p, UART_LCR, up->lcr | UART_LCR_DLAB);
+	if (!(serial_port_in(p, UART_LCR) & UART_LCR_DLAB))
+		goto idle_failed;
+
+	serial_dl_write(up, quot);
+	serial_port_out(p, UART_LCR, up->lcr);
+
+idle_failed:
+	dw8250_idle_exit(p);
 }
 
 /*
  * This function is being called as part of the uart_port::serial_out()
- * routine. Hence, it must not call serial_port_out() or serial_out()
- * against the modified registers here, i.e. LCR.
+ * routine. Hence, special care must be taken when serial_port_out() or
+ * serial_out() against the modified registers here, i.e. LCR (d->in_idle is
+ * used to break recursion loop).
  */
 static void dw8250_check_lcr(struct uart_port *p, unsigned int offset, u32 value)
 {
 	struct dw8250_data *d = to_dw8250_data(p->private_data);
-	void __iomem *addr = p->membase + (offset << p->regshift);
-	int tries = 1000;
+	u32 lcr;
+	int ret;
 
 	if (offset != UART_LCR || d->uart_16550_compatible)
 		return;
 
+	lcr = serial_port_in(p, UART_LCR);
+
 	/* Make sure LCR write wasn't ignored */
-	while (tries--) {
-		u32 lcr = serial_port_in(p, offset);
+	if ((value & ~UART_LCR_SPAR) == (lcr & ~UART_LCR_SPAR))
+		return;
 
-		if ((value & ~UART_LCR_SPAR) == (lcr & ~UART_LCR_SPAR))
-			return;
+	if (d->in_idle)
+		goto write_err;
 
-		dw8250_force_idle(p);
+	ret = dw8250_idle_enter(p);
+	if (ret < 0)
+		goto write_err;
 
-#ifdef CONFIG_64BIT
-		if (p->type == PORT_OCTEON)
-			__raw_writeq(value & 0xff, addr);
-		else
-#endif
-		if (p->iotype == UPIO_MEM32)
-			writel(value, addr);
-		else if (p->iotype == UPIO_MEM32BE)
-			iowrite32be(value, addr);
-		else
-			writeb(value, addr);
-	}
+	serial_port_out(p, UART_LCR, value);
+	dw8250_idle_exit(p);
+	return;
+
+write_err:
 	/*
 	 * FIXME: this deadlocks if port->lock is already held
 	 * dev_err(p->dev, "Couldn't set LCR to %d\n", value);
 	 */
+	return;		/* Silences "label at the end of compound statement" */
+}
+
+/*
+ * With BUSY, LCR writes can be very expensive (IRQ + complex retry logic).
+ * If the write does not change the value of the LCR register, skip it entirely.
+ */
+static bool dw8250_can_skip_reg_write(struct uart_port *p, unsigned int offset, u32 value)
+{
+	struct dw8250_data *d = to_dw8250_data(p->private_data);
+	u32 lcr;
+
+	if (offset != UART_LCR || d->uart_16550_compatible)
+		return false;
+
+	lcr = serial_port_in(p, offset);
+	return lcr == value;
 }
 
 /* Returns once the transmitter is empty or we run out of retries */
@@ -207,12 +314,18 @@ static void dw8250_tx_wait_empty(struct uart_port *p)
 
 static void dw8250_serial_out(struct uart_port *p, unsigned int offset, u32 value)
 {
+	if (dw8250_can_skip_reg_write(p, offset, value))
+		return;
+
 	writeb(value, p->membase + (offset << p->regshift));
 	dw8250_check_lcr(p, offset, value);
 }
 
 static void dw8250_serial_out38x(struct uart_port *p, unsigned int offset, u32 value)
 {
+	if (dw8250_can_skip_reg_write(p, offset, value))
+		return;
+
 	/* Allow the TX to drain before we reconfigure */
 	if (offset == UART_LCR)
 		dw8250_tx_wait_empty(p);
@@ -237,6 +350,9 @@ static u32 dw8250_serial_inq(struct uart_port *p, unsigned int offset)
 
 static void dw8250_serial_outq(struct uart_port *p, unsigned int offset, u32 value)
 {
+	if (dw8250_can_skip_reg_write(p, offset, value))
+		return;
+
 	value &= 0xff;
 	__raw_writeq(value, p->membase + (offset << p->regshift));
 	/* Read back to ensure register write ordering. */
@@ -248,6 +364,9 @@ static void dw8250_serial_outq(struct uart_port *p, unsigned int offset, u32 val
 
 static void dw8250_serial_out32(struct uart_port *p, unsigned int offset, u32 value)
 {
+	if (dw8250_can_skip_reg_write(p, offset, value))
+		return;
+
 	writel(value, p->membase + (offset << p->regshift));
 	dw8250_check_lcr(p, offset, value);
 }
@@ -261,6 +380,9 @@ static u32 dw8250_serial_in32(struct uart_port *p, unsigned int offset)
 
 static void dw8250_serial_out32be(struct uart_port *p, unsigned int offset, u32 value)
 {
+	if (dw8250_can_skip_reg_write(p, offset, value))
+		return;
+
 	iowrite32be(value, p->membase + (offset << p->regshift));
 	dw8250_check_lcr(p, offset, value);
 }
@@ -272,6 +394,29 @@ static u32 dw8250_serial_in32be(struct uart_port *p, unsigned int offset)
        return dw8250_modify_msr(p, offset, value);
 }
 
+/*
+ * INTC10EE UART can IRQ storm while reporting IIR_NO_INT. Inducing IIR value
+ * change has been observed to break the storm.
+ *
+ * If Tx is empty (THRE asserted), we use here IER_THRI to cause IIR_NO_INT ->
+ * IIR_THRI transition.
+ */
+static void dw8250_quirk_ier_kick(struct uart_port *p)
+{
+	struct uart_8250_port *up = up_to_u8250p(p);
+	u32 lsr;
+
+	if (up->ier & UART_IER_THRI)
+		return;
+
+	lsr = serial_lsr_in(up);
+	if (!(lsr & UART_LSR_THRE))
+		return;
+
+	serial_port_out(p, UART_IER, up->ier | UART_IER_THRI);
+	serial_port_in(p, UART_LCR);		/* safe, no side-effects */
+	serial_port_out(p, UART_IER, up->ier);
+}
 
 static int dw8250_handle_irq(struct uart_port *p)
 {
@@ -281,7 +426,31 @@ static int dw8250_handle_irq(struct uart_port *p)
 	bool rx_timeout = (iir & 0x3f) == UART_IIR_RX_TIMEOUT;
 	unsigned int quirks = d->pdata->quirks;
 	unsigned int status;
-	unsigned long flags;
+
+	guard(uart_port_lock_irqsave)(p);
+
+	switch (FIELD_GET(DW_UART_IIR_IID, iir)) {
+	case UART_IIR_NO_INT:
+		if (d->uart_16550_compatible || up->dma)
+			return 0;
+
+		if (quirks & DW_UART_QUIRK_IER_KICK &&
+		    d->no_int_count == (DW_UART_QUIRK_IER_KICK_THRES - 1))
+			dw8250_quirk_ier_kick(p);
+		d->no_int_count = (d->no_int_count + 1) % DW_UART_QUIRK_IER_KICK_THRES;
+
+		return 0;
+
+	case UART_IIR_BUSY:
+		/* Clear the USR */
+		serial_port_in(p, d->pdata->usr_reg);
+
+		d->no_int_count = 0;
+
+		return 1;
+	}
+
+	d->no_int_count = 0;
 
 	/*
 	 * There are ways to get Designware-based UARTs into a state where
@@ -294,20 +463,15 @@ static int dw8250_handle_irq(struct uart_port *p)
 	 * so we limit the workaround only to non-DMA mode.
 	 */
 	if (!up->dma && rx_timeout) {
-		uart_port_lock_irqsave(p, &flags);
 		status = serial_lsr_in(up);
 
 		if (!(status & (UART_LSR_DR | UART_LSR_BI)))
 			serial_port_in(p, UART_RX);
-
-		uart_port_unlock_irqrestore(p, flags);
 	}
 
 	/* Manually stop the Rx DMA transfer when acting as flow controller */
 	if (quirks & DW_UART_QUIRK_IS_DMA_FC && up->dma && up->dma->rx_running && rx_timeout) {
-		uart_port_lock_irqsave(p, &flags);
 		status = serial_lsr_in(up);
-		uart_port_unlock_irqrestore(p, flags);
 
 		if (status & (UART_LSR_DR | UART_LSR_BI)) {
 			dw8250_writel_ext(p, RZN1_UART_RDMACR, 0);
@@ -315,17 +479,9 @@ static int dw8250_handle_irq(struct uart_port *p)
 		}
 	}
 
-	if (serial8250_handle_irq(p, iir))
-		return 1;
+	serial8250_handle_irq_locked(p, iir);
 
-	if ((iir & UART_IIR_BUSY) == UART_IIR_BUSY) {
-		/* Clear the USR */
-		serial_port_in(p, d->pdata->usr_reg);
-
-		return 1;
-	}
-
-	return 0;
+	return 1;
 }
 
 static void dw8250_clk_work_cb(struct work_struct *work)
@@ -527,6 +683,14 @@ static void dw8250_reset_control_assert(void *data)
 	reset_control_assert(data);
 }
 
+static void dw8250_shutdown(struct uart_port *port)
+{
+	struct dw8250_data *d = to_dw8250_data(port->private_data);
+
+	serial8250_do_shutdown(port);
+	d->no_int_count = 0;
+}
+
 static int dw8250_probe(struct platform_device *pdev)
 {
 	struct uart_8250_port uart = {}, *up = &uart;
@@ -545,8 +709,10 @@ static int dw8250_probe(struct platform_device *pdev)
 	p->type		= PORT_8250;
 	p->flags	= UPF_FIXED_PORT;
 	p->dev		= dev;
+
 	p->set_ldisc	= dw8250_set_ldisc;
 	p->set_termios	= dw8250_set_termios;
+	p->set_divisor	= dw8250_set_divisor;
 
 	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 	if (!data)
@@ -654,10 +820,12 @@ static int dw8250_probe(struct platform_device *pdev)
 		dw8250_quirks(p, data);
 
 	/* If the Busy Functionality is not implemented, don't handle it */
-	if (data->uart_16550_compatible)
+	if (data->uart_16550_compatible) {
 		p->handle_irq = NULL;
-	else if (data->pdata)
+	} else if (data->pdata) {
 		p->handle_irq = dw8250_handle_irq;
+		p->shutdown = dw8250_shutdown;
+	}
 
 	dw8250_setup_dma_filter(p, data);
 
@@ -789,6 +957,11 @@ static const struct dw8250_platform_data dw8250_skip_set_rate_data = {
 	.quirks = DW_UART_QUIRK_SKIP_SET_RATE,
 };
 
+static const struct dw8250_platform_data dw8250_intc10ee = {
+	.usr_reg = DW_UART_USR,
+	.quirks = DW_UART_QUIRK_IER_KICK,
+};
+
 static const struct of_device_id dw8250_of_match[] = {
 	{ .compatible = "snps,dw-apb-uart", .data = &dw8250_dw_apb },
 	{ .compatible = "cavium,octeon-3860-uart", .data = &dw8250_octeon_3860_data },
@@ -818,7 +991,7 @@ static const struct acpi_device_id dw8250_acpi_match[] = {
 	{ "INT33C5", (kernel_ulong_t)&dw8250_dw_apb },
 	{ "INT3434", (kernel_ulong_t)&dw8250_dw_apb },
 	{ "INT3435", (kernel_ulong_t)&dw8250_dw_apb },
-	{ "INTC10EE", (kernel_ulong_t)&dw8250_dw_apb },
+	{ "INTC10EE", (kernel_ulong_t)&dw8250_intc10ee },
 	{ },
 };
 MODULE_DEVICE_TABLE(acpi, dw8250_acpi_match);
@@ -836,6 +1009,7 @@ static struct platform_driver dw8250_platform_driver = {
 
 module_platform_driver(dw8250_platform_driver);
 
+MODULE_IMPORT_NS("SERIAL_8250");
 MODULE_AUTHOR("Jamie Iles");
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Synopsys DesignWare 8250 serial port driver");
diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index aa1ab4da9ff1..6cfd1b2af5b7 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -137,6 +137,8 @@ struct serial_private {
 };
 
 #define PCI_DEVICE_ID_HPE_PCI_SERIAL	0x37e
+#define PCIE_VENDOR_ID_ASIX		0x125B
+#define PCIE_DEVICE_ID_AX99100		0x9100
 
 static const struct pci_device_id pci_use_msi[] = {
 	{ PCI_DEVICE_SUB(PCI_VENDOR_ID_NETMOS, PCI_DEVICE_ID_NETMOS_9900,
@@ -149,6 +151,8 @@ static const struct pci_device_id pci_use_msi[] = {
 			 0xA000, 0x1000) },
 	{ PCI_DEVICE_SUB(PCI_VENDOR_ID_HP_3PAR, PCI_DEVICE_ID_HPE_PCI_SERIAL,
 			 PCI_ANY_ID, PCI_ANY_ID) },
+	{ PCI_DEVICE_SUB(PCIE_VENDOR_ID_ASIX, PCIE_DEVICE_ID_AX99100,
+			 0xA000, 0x1000) },
 	{ }
 };
 
@@ -920,6 +924,7 @@ static int pci_netmos_init(struct pci_dev *dev)
 	case PCI_DEVICE_ID_NETMOS_9912:
 	case PCI_DEVICE_ID_NETMOS_9922:
 	case PCI_DEVICE_ID_NETMOS_9900:
+	case PCIE_DEVICE_ID_AX99100:
 		num_serial = pci_netmos_9900_numports(dev);
 		break;
 
@@ -2544,6 +2549,14 @@ static struct pci_serial_quirk pci_serial_quirks[] = {
 		.init		= pci_netmos_init,
 		.setup		= pci_netmos_9900_setup,
 	},
+	{
+		.vendor		= PCIE_VENDOR_ID_ASIX,
+		.device		= PCI_ANY_ID,
+		.subvendor	= PCI_ANY_ID,
+		.subdevice	= PCI_ANY_ID,
+		.init		= pci_netmos_init,
+		.setup		= pci_netmos_9900_setup,
+	},
 	/*
 	 * EndRun Technologies
 	*/
@@ -6065,6 +6078,10 @@ static const struct pci_device_id serial_pci_tbl[] = {
 		0xA000, 0x3002,
 		0, 0, pbn_NETMOS9900_2s_115200 },
 
+	{	PCIE_VENDOR_ID_ASIX, PCIE_DEVICE_ID_AX99100,
+		0xA000, 0x1000,
+		0, 0, pbn_b0_1_115200 },
+
 	/*
 	 * Best Connectivity and Rosewill PCI Multi I/O cards
 	 */
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index cc94af2d578a..328711b5df1a 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -18,6 +18,7 @@
 #include <linux/irq.h>
 #include <linux/console.h>
 #include <linux/gpio/consumer.h>
+#include <linux/lockdep.h>
 #include <linux/sysrq.h>
 #include <linux/delay.h>
 #include <linux/platform_device.h>
@@ -488,7 +489,7 @@ serial_port_out_sync(struct uart_port *p, int offset, int value)
 /*
  * FIFO support.
  */
-static void serial8250_clear_fifos(struct uart_8250_port *p)
+void serial8250_clear_fifos(struct uart_8250_port *p)
 {
 	if (p->capabilities & UART_CAP_FIFO) {
 		serial_out(p, UART_FCR, UART_FCR_ENABLE_FIFO);
@@ -497,6 +498,7 @@ static void serial8250_clear_fifos(struct uart_8250_port *p)
 		serial_out(p, UART_FCR, 0);
 	}
 }
+EXPORT_SYMBOL_NS_GPL(serial8250_clear_fifos, "SERIAL_8250");
 
 static enum hrtimer_restart serial8250_em485_handle_start_tx(struct hrtimer *t);
 static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t);
@@ -1782,20 +1784,16 @@ static bool handle_rx_dma(struct uart_8250_port *up, unsigned int iir)
 }
 
 /*
- * This handles the interrupt from one port.
+ * Context: port's lock must be held by the caller.
  */
-int serial8250_handle_irq(struct uart_port *port, unsigned int iir)
+void serial8250_handle_irq_locked(struct uart_port *port, unsigned int iir)
 {
 	struct uart_8250_port *up = up_to_u8250p(port);
 	struct tty_port *tport = &port->state->port;
 	bool skip_rx = false;
-	unsigned long flags;
 	u16 status;
 
-	if (iir & UART_IIR_NO_INT)
-		return 0;
-
-	uart_port_lock_irqsave(port, &flags);
+	lockdep_assert_held_once(&port->lock);
 
 	status = serial_lsr_in(up);
 
@@ -1828,8 +1826,19 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir)
 		else if (!up->dma->tx_running)
 			__stop_tx(up);
 	}
+}
+EXPORT_SYMBOL_NS_GPL(serial8250_handle_irq_locked, "SERIAL_8250");
 
-	uart_unlock_and_check_sysrq_irqrestore(port, flags);
+/*
+ * This handles the interrupt from one port.
+ */
+int serial8250_handle_irq(struct uart_port *port, unsigned int iir)
+{
+	if (iir & UART_IIR_NO_INT)
+		return 0;
+
+	guard(uart_port_lock_irqsave)(port);
+	serial8250_handle_irq_locked(port, iir);
 
 	return 1;
 }
@@ -2147,8 +2156,7 @@ static void serial8250_THRE_test(struct uart_port *port)
 	if (up->port.flags & UPF_NO_THRE_TEST)
 		return;
 
-	if (port->irqflags & IRQF_SHARED)
-		disable_irq_nosync(port->irq);
+	disable_irq(port->irq);
 
 	/*
 	 * Test for UARTs that do not reassert THRE when the transmitter is idle and the interrupt
@@ -2170,8 +2178,7 @@ static void serial8250_THRE_test(struct uart_port *port)
 		serial_port_out(port, UART_IER, 0);
 	}
 
-	if (port->irqflags & IRQF_SHARED)
-		enable_irq(port->irq);
+	enable_irq(port->irq);
 
 	/*
 	 * If the interrupt is not reasserted, or we otherwise don't trust the iir, setup a timer to
@@ -2350,6 +2357,7 @@ static int serial8250_startup(struct uart_port *port)
 void serial8250_do_shutdown(struct uart_port *port)
 {
 	struct uart_8250_port *up = up_to_u8250p(port);
+	u32 lcr;
 
 	serial8250_rpm_get(up);
 	/*
@@ -2376,13 +2384,13 @@ void serial8250_do_shutdown(struct uart_port *port)
 			port->mctrl &= ~TIOCM_OUT2;
 
 		serial8250_set_mctrl(port, port->mctrl);
+
+		/* Disable break condition */
+		lcr = serial_port_in(port, UART_LCR);
+		lcr &= ~UART_LCR_SBC;
+		serial_port_out(port, UART_LCR, lcr);
 	}
 
-	/*
-	 * Disable break condition and FIFOs
-	 */
-	serial_port_out(port, UART_LCR,
-			serial_port_in(port, UART_LCR) & ~UART_LCR_SBC);
 	serial8250_clear_fifos(up);
 
 	rsa_disable(up);
@@ -2392,6 +2400,12 @@ void serial8250_do_shutdown(struct uart_port *port)
 	 * the IRQ chain.
 	 */
 	serial_port_in(port, UART_RX);
+	/*
+	 * LCR writes on DW UART can trigger late (unmaskable) IRQs.
+	 * Handle them before releasing the handler.
+	 */
+	synchronize_irq(port->irq);
+
 	serial8250_rpm_put(up);
 
 	up->ops->release_irq(up);
@@ -3185,6 +3199,17 @@ void serial8250_set_defaults(struct uart_8250_port *up)
 }
 EXPORT_SYMBOL_GPL(serial8250_set_defaults);
 
+void serial8250_fifo_wait_for_lsr_thre(struct uart_8250_port *up, unsigned int count)
+{
+	unsigned int i;
+
+	for (i = 0; i < count; i++) {
+		if (wait_for_lsr(up, UART_LSR_THRE))
+			return;
+	}
+}
+EXPORT_SYMBOL_NS_GPL(serial8250_fifo_wait_for_lsr_thre, "SERIAL_8250");
+
 #ifdef CONFIG_SERIAL_8250_CONSOLE
 
 static void serial8250_console_putchar(struct uart_port *port, unsigned char ch)
@@ -3226,16 +3251,6 @@ static void serial8250_console_restore(struct uart_8250_port *up)
 	serial8250_out_MCR(up, up->mcr | UART_MCR_DTR | UART_MCR_RTS);
 }
 
-static void fifo_wait_for_lsr(struct uart_8250_port *up, unsigned int count)
-{
-	unsigned int i;
-
-	for (i = 0; i < count; i++) {
-		if (wait_for_lsr(up, UART_LSR_THRE))
-			return;
-	}
-}
-
 /*
  * Print a string to the serial port using the device FIFO
  *
@@ -3254,7 +3269,7 @@ static void serial8250_console_fifo_write(struct uart_8250_port *up,
 
 	while (s != end) {
 		/* Allow timeout for each byte of a possibly full FIFO */
-		fifo_wait_for_lsr(up, fifosize);
+		serial8250_fifo_wait_for_lsr_thre(up, fifosize);
 
 		for (i = 0; i < fifosize && s != end; ++i) {
 			if (*s == '\n' && !cr_sent) {
@@ -3272,7 +3287,7 @@ static void serial8250_console_fifo_write(struct uart_8250_port *up,
 	 * Allow timeout for each byte written since the caller will only wait
 	 * for UART_LSR_BOTH_EMPTY using the timeout of a single character
 	 */
-	fifo_wait_for_lsr(up, tx_count);
+	serial8250_fifo_wait_for_lsr_thre(up, tx_count);
 }
 
 /*
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 487756947a96..89cebdd27841 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -643,7 +643,10 @@ static unsigned int uart_write_room(struct tty_struct *tty)
 	unsigned int ret;
 
 	port = uart_port_ref_lock(state, &flags);
-	ret = kfifo_avail(&state->port.xmit_fifo);
+	if (!state->port.xmit_buf)
+		ret = 0;
+	else
+		ret = kfifo_avail(&state->port.xmit_fifo);
 	uart_port_unlock_deref(port, flags);
 	return ret;
 }
diff --git a/drivers/tty/serial/uartlite.c b/drivers/tty/serial/uartlite.c
index 39c1fd1ff9ce..6240c3d4dfd7 100644
--- a/drivers/tty/serial/uartlite.c
+++ b/drivers/tty/serial/uartlite.c
@@ -878,6 +878,7 @@ of_err:
 	pm_runtime_use_autosuspend(&pdev->dev);
 	pm_runtime_set_autosuspend_delay(&pdev->dev, UART_AUTOSUSPEND_TIMEOUT);
 	pm_runtime_set_active(&pdev->dev);
+	pm_runtime_get_noresume(&pdev->dev);
 	pm_runtime_enable(&pdev->dev);
 
 	ret = ulite_assign(&pdev->dev, id, res->start, irq, pdata);
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index c1f152d8b03b..e2df99e3d458 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -1339,6 +1339,8 @@ struct vc_data *vc_deallocate(unsigned int currcons)
 			kfree(vc->vc_saved_screen);
 			vc->vc_saved_screen = NULL;
 		}
+		vc_uniscr_free(vc->vc_saved_uni_lines);
+		vc->vc_saved_uni_lines = NULL;
 	}
 	return vc;
 }
@@ -1884,6 +1886,8 @@ static void enter_alt_screen(struct vc_data *vc)
 	vc->vc_saved_screen = kmemdup((u16 *)vc->vc_origin, size, GFP_KERNEL);
 	if (vc->vc_saved_screen == NULL)
 		return;
+	vc->vc_saved_uni_lines = vc->vc_uni_lines;
+	vc->vc_uni_lines = NULL;
 	vc->vc_saved_rows = vc->vc_rows;
 	vc->vc_saved_cols = vc->vc_cols;
 	save_cur(vc);
@@ -1905,6 +1909,8 @@ static void leave_alt_screen(struct vc_data *vc)
 		dest = ((u16 *)vc->vc_origin) + r * vc->vc_cols;
 		memcpy(dest, src, 2 * cols);
 	}
+	vc_uniscr_set(vc, vc->vc_saved_uni_lines);
+	vc->vc_saved_uni_lines = NULL;
 	restore_cur(vc);
 	/* Update the entire screen */
 	if (con_should_update(vc))
@@ -2227,6 +2233,8 @@ static void reset_terminal(struct vc_data *vc, int do_clear)
 	if (vc->vc_saved_screen != NULL) {
 		kfree(vc->vc_saved_screen);
 		vc->vc_saved_screen = NULL;
+		vc_uniscr_free(vc->vc_saved_uni_lines);
+		vc->vc_saved_uni_lines = NULL;
 		vc->vc_saved_rows = 0;
 		vc->vc_saved_cols = 0;
 	}
diff --git a/include/linux/console_struct.h b/include/linux/console_struct.h
index 13b35637bd5a..d5ca855116df 100644
--- a/include/linux/console_struct.h
+++ b/include/linux/console_struct.h
@@ -160,6 +160,7 @@ struct vc_data {
 	struct uni_pagedict **uni_pagedict_loc; /* [!] Location of uni_pagedict variable for this console */
 	u32 **vc_uni_lines;			/* unicode screen content */
 	u16		*vc_saved_screen;
+	u32		**vc_saved_uni_lines;
 	unsigned int	vc_saved_cols;
 	unsigned int	vc_saved_rows;
 	/* additional information is in vt_kern.h */
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index 01efdce0fda0..a95b2d143d24 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -195,6 +195,7 @@ void serial8250_do_set_mctrl(struct uart_port *port, unsigned int mctrl);
 void serial8250_do_set_divisor(struct uart_port *port, unsigned int baud,
 			       unsigned int quot);
 int fsl8250_handle_irq(struct uart_port *port);
+void serial8250_handle_irq_locked(struct uart_port *port, unsigned int iir);
 int serial8250_handle_irq(struct uart_port *port, unsigned int iir);
 u16 serial8250_rx_chars(struct uart_8250_port *up, u16 lsr);
 void serial8250_read_char(struct uart_8250_port *up, u16 lsr);