Merge tag 'tty-6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial driver updates from Greg KH:
 "Here is the big set of tty/serial driver updates for 6.5-rc1.

  Included in here are:

   - tty_audit code cleanups from Jiri

   - more 8250 cleanups from Ilpo

   - samsung_tty driver bugfixes

   - 8250 lock port updates

   - usual fsl_lpuart driver updates and fixes

   - other small serial driver fixes and updates, full details in the
     shortlog

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'tty-6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (58 commits)
  tty_audit: make data of tty_audit_log() const
  tty_audit: make tty pointers in exposed functions const
  tty_audit: make icanon a bool
  tty_audit: invert the condition in tty_audit_log()
  tty_audit: use kzalloc() in tty_audit_buf_alloc()
  tty_audit: use TASK_COMM_LEN for task comm
  Revert "8250: add support for ASIX devices with a FIFO bug"
  serial: atmel: don't enable IRQs prematurely
  tty: serial: Add Nuvoton ma35d1 serial driver support
  tty: serial: fsl_lpuart: add earlycon for imx8ulp platform
  tty: serial: imx: fix rs485 rx after tx
  selftests: tty: add selftest for tty timestamp updates
  tty: tty_io: update timestamps on all device nodes
  tty: fix hang on tty device with no_room set
  serial: core: fix -EPROBE_DEFER handling in init
  serial: 8250_omap: Use force_suspend and resume for system suspend
  tty: serial: samsung_tty: Use abs() to simplify some code
  tty: serial: samsung_tty: Fix a memory leak in s3c24xx_serial_getclk() when iterating clk
  tty: serial: samsung_tty: Fix a memory leak in s3c24xx_serial_getclk() in case of error
  serial: 8250: Apply FSL workarounds also without SERIAL_8250_CONSOLE
  ...

52 files changed, 2280 insertions, 425 deletions

diff --git a/arch/mips/alchemy/common/platform.c b/arch/mips/alchemy/common/platform.c
index b8f3397c59c9..d4ab34b3b404 100644
--- a/arch/mips/alchemy/common/platform.c
+++ b/arch/mips/alchemy/common/platform.c
@@ -51,9 +51,9 @@ static void alchemy_8250_pm(struct uart_port *port, unsigned int state,
 #define PORT(_base, _irq)					\
 	{							\
 		.mapbase	= _base,			\
+		.mapsize	= 0x1000,			\
 		.irq		= _irq,				\
 		.regshift	= 2,				\
-		.iotype		= UPIO_AU,			\
 		.flags		= UPF_SKIP_TEST | UPF_IOREMAP | \
 				  UPF_FIXED_TYPE,		\
 		.type		= PORT_16550A,			\
@@ -124,8 +124,14 @@ static void __init alchemy_setup_uarts(int ctype)
 	au1xx0_uart_device.dev.platform_data = ports;
 
 	/* Fill up uartclk. */
-	for (s = 0; s < c; s++)
+	for (s = 0; s < c; s++) {
 		ports[s].uartclk = uartclk;
+		if (au_platform_setup(&ports[s]) < 0) {
+			kfree(ports);
+			printk(KERN_INFO "Alchemy: missing support for UARTs\n");
+			return;
+		}
+	}
 	if (platform_device_register(&au1xx0_uart_device))
 		printk(KERN_INFO "Alchemy: failed to register UARTs\n");
 }
diff --git a/arch/powerpc/kernel/legacy_serial.c b/arch/powerpc/kernel/legacy_serial.c
index c9ad12461d44..6ee65741dbd5 100644
--- a/arch/powerpc/kernel/legacy_serial.c
+++ b/arch/powerpc/kernel/legacy_serial.c
@@ -508,12 +508,16 @@ static void __init fixup_port_irq(int index,
 
 	port->irq = virq;
 
-#ifdef CONFIG_SERIAL_8250_FSL
-	if (of_device_is_compatible(np, "fsl,ns16550")) {
-		port->handle_irq = fsl8250_handle_irq;
-		port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_8250_CONSOLE);
+	if (IS_ENABLED(CONFIG_SERIAL_8250) &&
+	    of_device_is_compatible(np, "fsl,ns16550")) {
+		if (IS_REACHABLE(CONFIG_SERIAL_8250_FSL)) {
+			port->handle_irq = fsl8250_handle_irq;
+			port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_8250_CONSOLE);
+		} else {
+			pr_warn_once("Not activating Freescale specific workaround for device %pOFP\n",
+				     np);
+		}
 	}
-#endif
 }
 
 static void __init fixup_port_pio(int index,
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 1c9e5d2ea7de..552e8a741562 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -203,8 +203,8 @@ static void n_tty_kick_worker(struct tty_struct *tty)
 	struct n_tty_data *ldata = tty->disc_data;
 
 	/* Did the input worker stop? Restart it */
-	if (unlikely(ldata->no_room)) {
-		ldata->no_room = 0;
+	if (unlikely(READ_ONCE(ldata->no_room))) {
+		WRITE_ONCE(ldata->no_room, 0);
 
 		WARN_RATELIMIT(tty->port->itty == NULL,
 				"scheduling with invalid itty\n");
@@ -1697,7 +1697,7 @@ n_tty_receive_buf_common(struct tty_struct *tty, const unsigned char *cp,
 			if (overflow && room < 0)
 				ldata->read_head--;
 			room = overflow;
-			ldata->no_room = flow && !room;
+			WRITE_ONCE(ldata->no_room, flow && !room);
 		} else
 			overflow = 0;
 
@@ -1728,6 +1728,17 @@ n_tty_receive_buf_common(struct tty_struct *tty, const unsigned char *cp,
 	} else
 		n_tty_check_throttle(tty);
 
+	if (unlikely(ldata->no_room)) {
+		/*
+		 * Barrier here is to ensure to read the latest read_tail in
+		 * chars_in_buffer() and to make sure that read_tail is not loaded
+		 * before ldata->no_room is set.
+		 */
+		smp_mb();
+		if (!chars_in_buffer(tty))
+			n_tty_kick_worker(tty);
+	}
+
 	up_read(&tty->termios_rwsem);
 
 	return rcvd;
@@ -2281,8 +2292,14 @@ more_to_be_read:
 		if (time)
 			timeout = time;
 	}
-	if (old_tail != ldata->read_tail)
+	if (old_tail != ldata->read_tail) {
+		/*
+		 * Make sure no_room is not read in n_tty_kick_worker()
+		 * before setting ldata->read_tail in copy_from_read_buf().
+		 */
+		smp_mb();
 		n_tty_kick_worker(tty);
+	}
 	up_read(&tty->termios_rwsem);
 
 	remove_wait_queue(&tty->read_wait, &wait);
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index 1e8fe44a7099..1aa3e55c8b47 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -91,7 +91,6 @@ struct serial8250_config {
 #define UART_BUG_TXEN	BIT(1)	/* UART has buggy TX IIR status */
 #define UART_BUG_NOMSR	BIT(2)	/* UART has buggy MSR status bits (Au1x00) */
 #define UART_BUG_THRE	BIT(3)	/* UART has buggy THRE reassertion */
-#define UART_BUG_PARITY	BIT(4)	/* UART mishandles parity if FIFO enabled */
 #define UART_BUG_TXRACE	BIT(5)	/* UART Tx fails to set remote DR */
 
 
@@ -167,18 +166,21 @@ static unsigned int __maybe_unused serial_icr_read(struct uart_8250_port *up,
 
 void serial8250_clear_and_reinit_fifos(struct uart_8250_port *p);
 
-static inline int serial_dl_read(struct uart_8250_port *up)
+static inline u32 serial_dl_read(struct uart_8250_port *up)
 {
 	return up->dl_read(up);
 }
 
-static inline void serial_dl_write(struct uart_8250_port *up, int value)
+static inline void serial_dl_write(struct uart_8250_port *up, u32 value)
 {
 	up->dl_write(up, value);
 }
 
 static inline bool serial8250_set_THRI(struct uart_8250_port *up)
 {
+	/* Port locked to synchronize UART_IER access against the console. */
+	lockdep_assert_held_once(&up->port.lock);
+
 	if (up->ier & UART_IER_THRI)
 		return false;
 	up->ier |= UART_IER_THRI;
@@ -188,6 +190,9 @@ static inline bool serial8250_set_THRI(struct uart_8250_port *up)
 
 static inline bool serial8250_clear_THRI(struct uart_8250_port *up)
 {
+	/* Port locked to synchronize UART_IER access against the console. */
+	lockdep_assert_held_once(&up->port.lock);
+
 	if (!(up->ier & UART_IER_THRI))
 		return false;
 	up->ier &= ~UART_IER_THRI;
diff --git a/drivers/tty/serial/8250/8250_aspeed_vuart.c b/drivers/tty/serial/8250/8250_aspeed_vuart.c
index 9d2a7856784f..4a9e71b2dbbc 100644
--- a/drivers/tty/serial/8250/8250_aspeed_vuart.c
+++ b/drivers/tty/serial/8250/8250_aspeed_vuart.c
@@ -275,6 +275,9 @@ static void __aspeed_vuart_set_throttle(struct uart_8250_port *up,
 {
 	unsigned char irqs = UART_IER_RLSI | UART_IER_RDI;
 
+	/* Port locked to synchronize UART_IER access against the console. */
+	lockdep_assert_held_once(&up->port.lock);
+
 	up->ier &= ~irqs;
 	if (!throttle)
 		up->ier |= irqs;
diff --git a/drivers/tty/serial/8250/8250_bcm7271.c b/drivers/tty/serial/8250/8250_bcm7271.c
index af0e1c070187..d4b05d7ad9e8 100644
--- a/drivers/tty/serial/8250/8250_bcm7271.c
+++ b/drivers/tty/serial/8250/8250_bcm7271.c
@@ -605,9 +605,13 @@ static int brcmuart_startup(struct uart_port *port)
 	/*
 	 * Disable the Receive Data Interrupt because the DMA engine
 	 * will handle this.
+	 *
+	 * Synchronize UART_IER access against the console.
 	 */
+	spin_lock_irq(&port->lock);
 	up->ier &= ~UART_IER_RDI;
 	serial_port_out(port, UART_IER, up->ier);
+	spin_unlock_irq(&port->lock);
 
 	priv->tx_running = false;
 	priv->dma.rx_dma = NULL;
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 13bf535eedcd..914e0e6251bf 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -488,6 +488,34 @@ static inline void serial8250_apply_quirks(struct uart_8250_port *up)
 	up->port.quirks |= skip_txen_test ? UPQ_NO_TXEN_TEST : 0;
 }
 
+static struct uart_8250_port *serial8250_setup_port(int index)
+{
+	struct uart_8250_port *up;
+
+	if (index >= UART_NR)
+		return NULL;
+
+	up = &serial8250_ports[index];
+	up->port.line = index;
+
+	serial8250_init_port(up);
+	if (!base_ops)
+		base_ops = up->port.ops;
+	up->port.ops = &univ8250_port_ops;
+
+	timer_setup(&up->timer, serial8250_timeout, 0);
+
+	up->ops = &univ8250_driver_ops;
+
+	if (IS_ENABLED(CONFIG_ALPHA_JENSEN) ||
+	    (IS_ENABLED(CONFIG_ALPHA_GENERIC) && alpha_jensen()))
+		up->port.set_mctrl = alpha_jensen_set_mctrl;
+
+	serial8250_set_defaults(up);
+
+	return up;
+}
+
 static void __init serial8250_isa_init_ports(void)
 {
 	struct uart_8250_port *up;
@@ -501,26 +529,13 @@ static void __init serial8250_isa_init_ports(void)
 	if (nr_uarts > UART_NR)
 		nr_uarts = UART_NR;
 
-	for (i = 0; i < nr_uarts; i++) {
-		struct uart_8250_port *up = &serial8250_ports[i];
-		struct uart_port *port = &up->port;
-
-		port->line = i;
-		serial8250_init_port(up);
-		if (!base_ops)
-			base_ops = port->ops;
-		port->ops = &univ8250_port_ops;
-
-		timer_setup(&up->timer, serial8250_timeout, 0);
-
-		up->ops = &univ8250_driver_ops;
-
-		if (IS_ENABLED(CONFIG_ALPHA_JENSEN) ||
-		    (IS_ENABLED(CONFIG_ALPHA_GENERIC) && alpha_jensen()))
-			port->set_mctrl = alpha_jensen_set_mctrl;
-
-		serial8250_set_defaults(up);
-	}
+	/*
+	 * Set up initial isa ports based on nr_uart module param, or else
+	 * default to CONFIG_SERIAL_8250_RUNTIME_UARTS. Note that we do not
+	 * need to increase nr_uarts when setting up the initial isa ports.
+	 */
+	for (i = 0; i < nr_uarts; i++)
+		serial8250_setup_port(i);
 
 	/* chain base port ops to support Remote Supervisor Adapter */
 	univ8250_port_ops = *base_ops;
@@ -586,16 +601,29 @@ static void univ8250_console_write(struct console *co, const char *s,
 
 static int univ8250_console_setup(struct console *co, char *options)
 {
+	struct uart_8250_port *up;
 	struct uart_port *port;
-	int retval;
+	int retval, i;
 
 	/*
 	 * Check whether an invalid uart number has been specified, and
 	 * if so, search for the first available port that does have
 	 * console support.
 	 */
-	if (co->index >= nr_uarts)
+	if (co->index >= UART_NR)
 		co->index = 0;
+
+	/*
+	 * If the console is past the initial isa ports, init more ports up to
+	 * co->index as needed and increment nr_uarts accordingly.
+	 */
+	for (i = nr_uarts; i <= co->index; i++) {
+		up = serial8250_setup_port(i);
+		if (!up)
+			return -ENODEV;
+		nr_uarts++;
+	}
+
 	port = &serial8250_ports[co->index].port;
 	/* link port to console */
 	port->cons = co;
@@ -822,12 +850,16 @@ static int serial8250_probe(struct platform_device *dev)
 		uart.port.iotype	= p->iotype;
 		uart.port.flags		= p->flags;
 		uart.port.mapbase	= p->mapbase;
+		uart.port.mapsize	= p->mapsize;
 		uart.port.hub6		= p->hub6;
 		uart.port.has_sysrq	= p->has_sysrq;
 		uart.port.private_data	= p->private_data;
 		uart.port.type		= p->type;
+		uart.bugs		= p->bugs;
 		uart.port.serial_in	= p->serial_in;
 		uart.port.serial_out	= p->serial_out;
+		uart.dl_read		= p->dl_read;
+		uart.dl_write		= p->dl_write;
 		uart.port.handle_irq	= p->handle_irq;
 		uart.port.handle_break	= p->handle_break;
 		uart.port.set_termios	= p->set_termios;
@@ -990,12 +1022,24 @@ int serial8250_register_8250_port(const struct uart_8250_port *up)
 	mutex_lock(&serial_mutex);
 
 	uart = serial8250_find_match_or_unused(&up->port);
-	if (uart && uart->port.type != PORT_8250_CIR) {
+	if (!uart) {
+		/*
+		 * If the port is past the initial isa ports, initialize a new
+		 * port and increment nr_uarts accordingly.
+		 */
+		uart = serial8250_setup_port(nr_uarts);
+		if (!uart)
+			goto unlock;
+		nr_uarts++;
+	}
+
+	if (uart->port.type != PORT_8250_CIR) {
 		struct mctrl_gpios *gpios;
 
 		if (uart->port.dev)
 			uart_remove_one_port(&serial8250_reg, &uart->port);
 
+		uart->port.ctrl_id	= up->port.ctrl_id;
 		uart->port.iobase       = up->port.iobase;
 		uart->port.membase      = up->port.membase;
 		uart->port.irq          = up->port.irq;
@@ -1120,6 +1164,7 @@ int serial8250_register_8250_port(const struct uart_8250_port *up)
 		}
 	}
 
+unlock:
 	mutex_unlock(&serial_mutex);
 
 	return ret;
diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index 0ebde0ab8167..4299a8bd83d9 100644
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -36,7 +36,6 @@
 
 static unsigned int serial8250_early_in(struct uart_port *port, int offset)
 {
-	int reg_offset = offset;
 	offset <<= port->regshift;
 
 	switch (port->iotype) {
@@ -50,8 +49,6 @@ static unsigned int serial8250_early_in(struct uart_port *port, int offset)
 		return ioread32be(port->membase + offset);
 	case UPIO_PORT:
 		return inb(port->iobase + offset);
-	case UPIO_AU:
-		return port->serial_in(port, reg_offset);
 	default:
 		return 0;
 	}
@@ -59,7 +56,6 @@ static unsigned int serial8250_early_in(struct uart_port *port, int offset)
 
 static void serial8250_early_out(struct uart_port *port, int offset, int value)
 {
-	int reg_offset = offset;
 	offset <<= port->regshift;
 
 	switch (port->iotype) {
@@ -78,9 +74,6 @@ static void serial8250_early_out(struct uart_port *port, int offset, int value)
 	case UPIO_PORT:
 		outb(value, port->iobase + offset);
 		break;
-	case UPIO_AU:
-		port->serial_out(port, reg_offset, value);
-		break;
 	}
 }
 
@@ -199,17 +192,3 @@ OF_EARLYCON_DECLARE(omap8250, "ti,omap3-uart", early_omap8250_setup);
 OF_EARLYCON_DECLARE(omap8250, "ti,omap4-uart", early_omap8250_setup);
 
 #endif
-
-#ifdef CONFIG_SERIAL_8250_RT288X
-
-static int __init early_au_setup(struct earlycon_device *dev, const char *opt)
-{
-	dev->port.serial_in = au_serial_in;
-	dev->port.serial_out = au_serial_out;
-	dev->port.iotype = UPIO_AU;
-	dev->con->write = early_serial8250_write;
-	return 0;
-}
-OF_EARLYCON_DECLARE(palmchip, "ralink,rt2880-uart", early_au_setup);
-
-#endif
diff --git a/drivers/tty/serial/8250/8250_em.c b/drivers/tty/serial/8250/8250_em.c
index 25a9ecf26be6..ef5019e944ea 100644
--- a/drivers/tty/serial/8250/8250_em.c
+++ b/drivers/tty/serial/8250/8250_em.c
@@ -139,12 +139,12 @@ static void serial8250_em_serial_out(struct uart_port *p, int offset, int value)
 	}
 }
 
-static int serial8250_em_serial_dl_read(struct uart_8250_port *up)
+static u32 serial8250_em_serial_dl_read(struct uart_8250_port *up)
 {
 	return serial_in(up, UART_DLL_EM) | serial_in(up, UART_DLM_EM) << 8;
 }
 
-static void serial8250_em_serial_dl_write(struct uart_8250_port *up, int value)
+static void serial8250_em_serial_dl_write(struct uart_8250_port *up, u32 value)
 {
 	serial_out(up, UART_DLL_EM, value & 0xff);
 	serial_out(up, UART_DLM_EM, value >> 8 & 0xff);
diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
index b406cba10b0e..077c3ba3539e 100644
--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -198,8 +198,12 @@ static int xr17v35x_startup(struct uart_port *port)
 	/*
 	 * Make sure all interrups are masked until initialization is
 	 * complete and the FIFOs are cleared
+	 *
+	 * Synchronize UART_IER access against the console.
 	 */
+	spin_lock_irq(&port->lock);
 	serial_port_out(port, UART_IER, 0);
+	spin_unlock_irq(&port->lock);
 
 	return serial8250_do_startup(port);
 }
diff --git a/drivers/tty/serial/8250/8250_fsl.c b/drivers/tty/serial/8250/8250_fsl.c
index 8adfaa183f77..6af4e1c1210a 100644
--- a/drivers/tty/serial/8250/8250_fsl.c
+++ b/drivers/tty/serial/8250/8250_fsl.c
@@ -38,7 +38,19 @@ int fsl8250_handle_irq(struct uart_port *port)
 		return 0;
 	}
 
-	/* This is the WAR; if last event was BRK, then read and return */
+	/*
+	 * For a single break the hardware reports LSR.BI for each character
+	 * time. This is described in the MPC8313E chip errata as "General17".
+	 * A typical break has a duration of 0.3s, with a 115200n8 configuration
+	 * that (theoretically) corresponds to ~3500 interrupts in these 0.3s.
+	 * In practise it's less (around 500) because of hardware
+	 * and software latencies. The workaround recommended by the vendor is
+	 * to read the RX register (to clear LSR.DR and thus prevent a FIFO
+	 * aging interrupt). To prevent the irq from retriggering LSR must not be
+	 * read. (This would clear LSR.BI, hardware would reassert the BI event
+	 * immediately and interrupt the CPU again. The hardware clears LSR.BI
+	 * when the next valid char is read.)
+	 */
 	if (unlikely(up->lsr_saved_flags & UART_LSR_BI)) {
 		up->lsr_saved_flags &= ~UART_LSR_BI;
 		port->serial_in(port, UART_RX);
@@ -172,3 +184,6 @@ static struct platform_driver fsl8250_platform_driver = {
 
 module_platform_driver(fsl8250_platform_driver);
 #endif
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Handling of Freescale specific 8250 variants");
diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
index fb1d5ec0940e..74da5676ce67 100644
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -222,11 +222,17 @@ static void mtk8250_shutdown(struct uart_port *port)
 
 static void mtk8250_disable_intrs(struct uart_8250_port *up, int mask)
 {
+	/* Port locked to synchronize UART_IER access against the console. */
+	lockdep_assert_held_once(&up->port.lock);
+
 	serial_out(up, UART_IER, serial_in(up, UART_IER) & (~mask));
 }
 
 static void mtk8250_enable_intrs(struct uart_8250_port *up, int mask)
 {
+	/* Port locked to synchronize UART_IER access against the console. */
+	lockdep_assert_held_once(&up->port.lock);
+
 	serial_out(up, UART_IER, serial_in(up, UART_IER) | mask);
 }
 
@@ -235,6 +241,9 @@ 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);
 
+	/* Port locked to synchronize UART_IER access against the console. */
+	lockdep_assert_held_once(&port->lock);
+
 	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);
@@ -422,12 +431,7 @@ static int __maybe_unused mtk8250_runtime_suspend(struct device *dev)
 	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--;
-	}
+	clk_disable_unprepare(data->bus_clk);
 
 	return 0;
 }
@@ -435,19 +439,8 @@ static int __maybe_unused mtk8250_runtime_suspend(struct device *dev)
 static int __maybe_unused mtk8250_runtime_resume(struct device *dev)
 {
 	struct mtk8250_data *data = dev_get_drvdata(dev);
-	int 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++;
-	}
+	clk_prepare_enable(data->bus_clk);
 
 	return 0;
 }
@@ -456,14 +449,12 @@ static void
 mtk8250_do_pm(struct uart_port *port, unsigned int state, unsigned int old)
 {
 	if (!state)
-		if (!mtk8250_runtime_resume(port->dev))
-			pm_runtime_get_sync(port->dev);
+		pm_runtime_get_sync(port->dev);
 
 	serial8250_do_pm(port, state, old);
 
 	if (state)
-		if (!pm_runtime_put_sync_suspend(port->dev))
-			mtk8250_runtime_suspend(port->dev);
+		pm_runtime_put_sync_suspend(port->dev);
 }
 
 #ifdef CONFIG_SERIAL_8250_DMA
@@ -495,7 +486,7 @@ static int mtk8250_probe_of(struct platform_device *pdev, struct uart_port *p,
 		return 0;
 	}
 
-	data->bus_clk = devm_clk_get(&pdev->dev, "bus");
+	data->bus_clk = devm_clk_get_enabled(&pdev->dev, "bus");
 	if (IS_ERR(data->bus_clk))
 		return PTR_ERR(data->bus_clk);
 
@@ -578,25 +569,16 @@ static int mtk8250_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, data);
 
-	pm_runtime_enable(&pdev->dev);
-	err = mtk8250_runtime_resume(&pdev->dev);