Initial import

1 files changed, 782 insertions, 0 deletions

diff --git a/drivers/tty/serial/vt8500_serial.c b/drivers/tty/serial/vt8500_serial.c
new file mode 100644
index 000000000..4079ec56f
--- /dev/null
+++ b/drivers/tty/serial/vt8500_serial.c
@@ -0,0 +1,782 @@
+/*
+ * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
+ *
+ * Based on msm_serial.c, which is:
+ * Copyright (C) 2007 Google, Inc.
+ * Author: Robert Love <rlove@google.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#if defined(CONFIG_SERIAL_VT8500_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
+# define SUPPORT_SYSRQ
+#endif
+
+#include <linux/hrtimer.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/irq.h>
+#include <linux/init.h>
+#include <linux/console.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/serial_core.h>
+#include <linux/serial.h>
+#include <linux/slab.h>
+#include <linux/clk.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/err.h>
+
+/*
+ * UART Register offsets
+ */
+
+#define VT8500_URTDR		0x0000	/* Transmit data */
+#define VT8500_URRDR		0x0004	/* Receive data */
+#define VT8500_URDIV		0x0008	/* Clock/Baud rate divisor */
+#define VT8500_URLCR		0x000C	/* Line control */
+#define VT8500_URICR		0x0010	/* IrDA control */
+#define VT8500_URIER		0x0014	/* Interrupt enable */
+#define VT8500_URISR		0x0018	/* Interrupt status */
+#define VT8500_URUSR		0x001c	/* UART status */
+#define VT8500_URFCR		0x0020	/* FIFO control */
+#define VT8500_URFIDX		0x0024	/* FIFO index */
+#define VT8500_URBKR		0x0028	/* Break signal count */
+#define VT8500_URTOD		0x002c	/* Time out divisor */
+#define VT8500_TXFIFO		0x1000	/* Transmit FIFO (16x8) */
+#define VT8500_RXFIFO		0x1020	/* Receive FIFO (16x10) */
+
+/*
+ * Interrupt enable and status bits
+ */
+
+#define TXDE	(1 << 0)	/* Tx Data empty */
+#define RXDF	(1 << 1)	/* Rx Data full */
+#define TXFAE	(1 << 2)	/* Tx FIFO almost empty */
+#define TXFE	(1 << 3)	/* Tx FIFO empty */
+#define RXFAF	(1 << 4)	/* Rx FIFO almost full */
+#define RXFF	(1 << 5)	/* Rx FIFO full */
+#define TXUDR	(1 << 6)	/* Tx underrun */
+#define RXOVER	(1 << 7)	/* Rx overrun */
+#define PER	(1 << 8)	/* Parity error */
+#define FER	(1 << 9)	/* Frame error */
+#define TCTS	(1 << 10)	/* Toggle of CTS */
+#define RXTOUT	(1 << 11)	/* Rx timeout */
+#define BKDONE	(1 << 12)	/* Break signal done */
+#define ERR	(1 << 13)	/* AHB error response */
+
+#define RX_FIFO_INTS	(RXFAF | RXFF | RXOVER | PER | FER | RXTOUT)
+#define TX_FIFO_INTS	(TXFAE | TXFE | TXUDR)
+
+/*
+ * Line control bits
+ */
+
+#define VT8500_TXEN	(1 << 0)	/* Enable transmit logic */
+#define VT8500_RXEN	(1 << 1)	/* Enable receive logic */
+#define VT8500_CS8	(1 << 2)	/* 8-bit data length (vs. 7-bit) */
+#define VT8500_CSTOPB	(1 << 3)	/* 2 stop bits (vs. 1) */
+#define VT8500_PARENB	(1 << 4)	/* Enable parity */
+#define VT8500_PARODD	(1 << 5)	/* Odd parity (vs. even) */
+#define VT8500_RTS	(1 << 6)	/* Ready to send */
+#define VT8500_LOOPBK	(1 << 7)	/* Enable internal loopback */
+#define VT8500_DMA	(1 << 8)	/* Enable DMA mode (needs FIFO) */
+#define VT8500_BREAK	(1 << 9)	/* Initiate break signal */
+#define VT8500_PSLVERR	(1 << 10)	/* APB error upon empty RX FIFO read */
+#define VT8500_SWRTSCTS	(1 << 11)	/* Software-controlled RTS/CTS */
+
+/*
+ * Capability flags (driver-internal)
+ */
+
+#define VT8500_HAS_SWRTSCTS_SWITCH	(1 << 1)
+
+#define VT8500_RECOMMENDED_CLK		12000000
+#define VT8500_OVERSAMPLING_DIVISOR	13
+#define VT8500_MAX_PORTS	6
+
+struct vt8500_port {
+	struct uart_port	uart;
+	char			name[16];
+	struct clk		*clk;
+	unsigned int		clk_predivisor;
+	unsigned int		ier;
+	unsigned int		vt8500_uart_flags;
+};
+
+/*
+ * we use this variable to keep track of which ports
+ * have been allocated as we can't use pdev->id in
+ * devicetree
+ */
+static unsigned long vt8500_ports_in_use;
+
+static inline void vt8500_write(struct uart_port *port, unsigned int val,
+			     unsigned int off)
+{
+	writel(val, port->membase + off);
+}
+
+static inline unsigned int vt8500_read(struct uart_port *port, unsigned int off)
+{
+	return readl(port->membase + off);
+}
+
+static void vt8500_stop_tx(struct uart_port *port)
+{
+	struct vt8500_port *vt8500_port = container_of(port,
+						       struct vt8500_port,
+						       uart);
+
+	vt8500_port->ier &= ~TX_FIFO_INTS;
+	vt8500_write(port, vt8500_port->ier, VT8500_URIER);
+}
+
+static void vt8500_stop_rx(struct uart_port *port)
+{
+	struct vt8500_port *vt8500_port = container_of(port,
+						       struct vt8500_port,
+						       uart);
+
+	vt8500_port->ier &= ~RX_FIFO_INTS;
+	vt8500_write(port, vt8500_port->ier, VT8500_URIER);
+}
+
+static void vt8500_enable_ms(struct uart_port *port)
+{
+	struct vt8500_port *vt8500_port = container_of(port,
+						       struct vt8500_port,
+						       uart);
+
+	vt8500_port->ier |= TCTS;
+	vt8500_write(port, vt8500_port->ier, VT8500_URIER);
+}
+
+static void handle_rx(struct uart_port *port)
+{
+	struct tty_port *tport = &port->state->port;
+
+	/*
+	 * Handle overrun
+	 */
+	if ((vt8500_read(port, VT8500_URISR) & RXOVER)) {
+		port->icount.overrun++;
+		tty_insert_flip_char(tport, 0, TTY_OVERRUN);
+	}
+
+	/* and now the main RX loop */
+	while (vt8500_read(port, VT8500_URFIDX) & 0x1f00) {
+		unsigned int c;
+		char flag = TTY_NORMAL;
+
+		c = readw(port->membase + VT8500_RXFIFO) & 0x3ff;
+
+		/* Mask conditions we're ignorning. */
+		c &= ~port->read_status_mask;
+
+		if (c & FER) {
+			port->icount.frame++;
+			flag = TTY_FRAME;
+		} else if (c & PER) {
+			port->icount.parity++;
+			flag = TTY_PARITY;
+		}
+		port->icount.rx++;
+
+		if (!uart_handle_sysrq_char(port, c))
+			tty_insert_flip_char(tport, c, flag);
+	}
+
+	spin_unlock(&port->lock);
+	tty_flip_buffer_push(tport);
+	spin_lock(&port->lock);
+}
+
+static void handle_tx(struct uart_port *port)
+{
+	struct circ_buf *xmit = &port->state->xmit;
+
+	if (port->x_char) {
+		writeb(port->x_char, port->membase + VT8500_TXFIFO);
+		port->icount.tx++;
+		port->x_char = 0;
+	}
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+		vt8500_stop_tx(port);
+		return;
+	}
+
+	while ((vt8500_read(port, VT8500_URFIDX) & 0x1f) < 16) {
+		if (uart_circ_empty(xmit))
+			break;
+
+		writeb(xmit->buf[xmit->tail], port->membase + VT8500_TXFIFO);
+
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		port->icount.tx++;
+	}
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+
+	if (uart_circ_empty(xmit))
+		vt8500_stop_tx(port);
+}
+
+static void vt8500_start_tx(struct uart_port *port)
+{
+	struct vt8500_port *vt8500_port = container_of(port,
+						       struct vt8500_port,
+						       uart);
+
+	vt8500_port->ier &= ~TX_FIFO_INTS;
+	vt8500_write(port, vt8500_port->ier, VT8500_URIER);
+	handle_tx(port);
+	vt8500_port->ier |= TX_FIFO_INTS;
+	vt8500_write(port, vt8500_port->ier, VT8500_URIER);
+}
+
+static void handle_delta_cts(struct uart_port *port)
+{
+	port->icount.cts++;
+	wake_up_interruptible(&port->state->port.delta_msr_wait);
+}
+
+static irqreturn_t vt8500_irq(int irq, void *dev_id)
+{
+	struct uart_port *port = dev_id;
+	unsigned long isr;
+
+	spin_lock(&port->lock);
+	isr = vt8500_read(port, VT8500_URISR);
+
+	/* Acknowledge active status bits */
+	vt8500_write(port, isr, VT8500_URISR);
+
+	if (isr & RX_FIFO_INTS)
+		handle_rx(port);
+	if (isr & TX_FIFO_INTS)
+		handle_tx(port);
+	if (isr & TCTS)
+		handle_delta_cts(port);
+
+	spin_unlock(&port->lock);
+
+	return IRQ_HANDLED;
+}
+
+static unsigned int vt8500_tx_empty(struct uart_port *port)
+{
+	return (vt8500_read(port, VT8500_URFIDX) & 0x1f) < 16 ?
+						TIOCSER_TEMT : 0;
+}
+
+static unsigned int vt8500_get_mctrl(struct uart_port *port)
+{
+	unsigned int usr;
+
+	usr = vt8500_read(port, VT8500_URUSR);
+	if (usr & (1 << 4))
+		return TIOCM_CTS;
+	else
+		return 0;
+}
+
+static void vt8500_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+	unsigned int lcr = vt8500_read(port, VT8500_URLCR);
+
+	if (mctrl & TIOCM_RTS)
+		lcr |= VT8500_RTS;
+	else
+		lcr &= ~VT8500_RTS;
+
+	vt8500_write(port, lcr, VT8500_URLCR);
+}
+
+static void vt8500_break_ctl(struct uart_port *port, int break_ctl)
+{
+	if (break_ctl)
+		vt8500_write(port,
+			     vt8500_read(port, VT8500_URLCR) | VT8500_BREAK,
+			     VT8500_URLCR);
+}
+
+static int vt8500_set_baud_rate(struct uart_port *port, unsigned int baud)
+{
+	struct vt8500_port *vt8500_port =
+			container_of(port, struct vt8500_port, uart);
+	unsigned long div;
+	unsigned int loops = 1000;
+
+	div = ((vt8500_port->clk_predivisor - 1) & 0xf) << 16;
+	div |= (uart_get_divisor(port, baud) - 1) & 0x3ff;
+
+	/* Effective baud rate */
+	baud = port->uartclk / 16 / ((div & 0x3ff) + 1);
+
+	while ((vt8500_read(port, VT8500_URUSR) & (1 << 5)) && --loops)
+		cpu_relax();
+
+	vt8500_write(port, div, VT8500_URDIV);
+
+	/* Break signal timing depends on baud rate, update accordingly */
+	vt8500_write(port, mult_frac(baud, 4096, 1000000), VT8500_URBKR);
+
+	return baud;
+}
+
+static int vt8500_startup(struct uart_port *port)
+{
+	struct vt8500_port *vt8500_port =
+			container_of(port, struct vt8500_port, uart);
+	int ret;
+
+	snprintf(vt8500_port->name, sizeof(vt8500_port->name),
+		 "vt8500_serial%d", port->line);
+
+	ret = request_irq(port->irq, vt8500_irq, IRQF_TRIGGER_HIGH,
+			  vt8500_port->name, port);
+	if (unlikely(ret))
+		return ret;
+
+	vt8500_write(port, 0x03, VT8500_URLCR);	/* enable TX & RX */
+
+	return 0;
+}
+
+static void vt8500_shutdown(struct uart_port *port)
+{
+	struct vt8500_port *vt8500_port =
+			container_of(port, struct vt8500_port, uart);
+
+	vt8500_port->ier = 0;
+
+	/* disable interrupts and FIFOs */
+	vt8500_write(&vt8500_port->uart, 0, VT8500_URIER);
+	vt8500_write(&vt8500_port->uart, 0x880, VT8500_URFCR);
+	free_irq(port->irq, port);
+}
+
+static void vt8500_set_termios(struct uart_port *port,
+			       struct ktermios *termios,
+			       struct ktermios *old)
+{
+	struct vt8500_port *vt8500_port =
+			container_of(port, struct vt8500_port, uart);
+	unsigned long flags;
+	unsigned int baud, lcr;
+	unsigned int loops = 1000;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	/* calculate and set baud rate */
+	baud = uart_get_baud_rate(port, termios, old, 900, 921600);
+	baud = vt8500_set_baud_rate(port, baud);
+	if (tty_termios_baud_rate(termios))
+		tty_termios_encode_baud_rate(termios, baud, baud);
+
+	/* calculate parity */
+	lcr = vt8500_read(&vt8500_port->uart, VT8500_URLCR);
+	lcr &= ~(VT8500_PARENB | VT8500_PARODD);
+	if (termios->c_cflag & PARENB) {
+		lcr |= VT8500_PARENB;
+		termios->c_cflag &= ~CMSPAR;
+		if (termios->c_cflag & PARODD)
+			lcr |= VT8500_PARODD;
+	}
+
+	/* calculate bits per char */
+	lcr &= ~VT8500_CS8;
+	switch (termios->c_cflag & CSIZE) {
+	case CS7:
+		break;
+	case CS8:
+	default:
+		lcr |= VT8500_CS8;
+		termios->c_cflag &= ~CSIZE;
+		termios->c_cflag |= CS8;
+		break;
+	}
+
+	/* calculate stop bits */
+	lcr &= ~VT8500_CSTOPB;
+	if (termios->c_cflag & CSTOPB)
+		lcr |= VT8500_CSTOPB;
+
+	lcr &= ~VT8500_SWRTSCTS;
+	if (vt8500_port->vt8500_uart_flags & VT8500_HAS_SWRTSCTS_SWITCH)
+		lcr |= VT8500_SWRTSCTS;
+
+	/* set parity, bits per char, and stop bit */
+	vt8500_write(&vt8500_port->uart, lcr, VT8500_URLCR);
+
+	/* Configure status bits to ignore based on termio flags. */
+	port->read_status_mask = 0;
+	if (termios->c_iflag & IGNPAR)
+		port->read_status_mask = FER | PER;
+
+	uart_update_timeout(port, termios->c_cflag, baud);
+
+	/* Reset FIFOs */
+	vt8500_write(&vt8500_port->uart, 0x88c, VT8500_URFCR);
+	while ((vt8500_read(&vt8500_port->uart, VT8500_URFCR) & 0xc)
+							&& --loops)
+		cpu_relax();
+
+	/* Every possible FIFO-related interrupt */
+	vt8500_port->ier = RX_FIFO_INTS | TX_FIFO_INTS;
+
+	/*
+	 * CTS flow control
+	 */
+	if (UART_ENABLE_MS(&vt8500_port->uart, termios->c_cflag))
+		vt8500_port->ier |= TCTS;
+
+	vt8500_write(&vt8500_port->uart, 0x881, VT8500_URFCR);
+	vt8500_write(&vt8500_port->uart, vt8500_port->ier, VT8500_URIER);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static const char *vt8500_type(struct uart_port *port)
+{
+	struct vt8500_port *vt8500_port =
+			container_of(port, struct vt8500_port, uart);
+	return vt8500_port->name;
+}
+
+static void vt8500_release_port(struct uart_port *port)
+{
+}
+
+static int vt8500_request_port(struct uart_port *port)
+{
+	return 0;
+}
+
+static void vt8500_config_port(struct uart_port *port, int flags)
+{
+	port->type = PORT_VT8500;
+}
+
+static int vt8500_verify_port(struct uart_port *port,
+			      struct serial_struct *ser)
+{
+	if (unlikely(ser->type != PORT_UNKNOWN && ser->type != PORT_VT8500))
+		return -EINVAL;
+	if (unlikely(port->irq != ser->irq))
+		return -EINVAL;
+	return 0;
+}
+
+static struct vt8500_port *vt8500_uart_ports[VT8500_MAX_PORTS];
+static struct uart_driver vt8500_uart_driver;
+
+#ifdef CONFIG_SERIAL_VT8500_CONSOLE
+
+static inline void wait_for_xmitr(struct uart_port *port)
+{
+	unsigned int status, tmout = 10000;
+
+	/* Wait up to 10ms for the character(s) to be sent. */
+	do {
+		status = vt8500_read(port, VT8500_URFIDX);
+
+		if (--tmout == 0)
+			break;
+		udelay(1);
+	} while (status & 0x10);
+}
+
+static void vt8500_console_putchar(struct uart_port *port, int c)
+{
+	wait_for_xmitr(port);
+	writeb(c, port->membase + VT8500_TXFIFO);
+}
+
+static void vt8500_console_write(struct console *co, const char *s,
+			      unsigned int count)
+{
+	struct vt8500_port *vt8500_port = vt8500_uart_ports[co->index];
+	unsigned long ier;
+
+	BUG_ON(co->index < 0 || co->index >= vt8500_uart_driver.nr);
+
+	ier = vt8500_read(&vt8500_port->uart, VT8500_URIER);
+	vt8500_write(&vt8500_port->uart, VT8500_URIER, 0);
+
+	uart_console_write(&vt8500_port->uart, s, count,
+			   vt8500_console_putchar);
+
+	/*
+	 *	Finally, wait for transmitter to become empty
+	 *	and switch back to FIFO
+	 */
+	wait_for_xmitr(&vt8500_port->uart);
+	vt8500_write(&vt8500_port->uart, VT8500_URIER, ier);
+}
+
+static int __init vt8500_console_setup(struct console *co, char *options)
+{
+	struct vt8500_port *vt8500_port;
+	int baud = 9600;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+
+	if (unlikely(co->index >= vt8500_uart_driver.nr || co->index < 0))
+		return -ENXIO;
+
+	vt8500_port = vt8500_uart_ports[co->index];
+
+	if (!vt8500_port)
+		return -ENODEV;
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	return uart_set_options(&vt8500_port->uart,
+				 co, baud, parity, bits, flow);
+}
+
+static struct console vt8500_console = {
+	.name = "ttyWMT",
+	.write = vt8500_console_write,
+	.device = uart_console_device,
+	.setup = vt8500_console_setup,
+	.flags = CON_PRINTBUFFER,
+	.index = -1,
+	.data = &vt8500_uart_driver,
+};
+
+#define VT8500_CONSOLE	(&vt8500_console)
+
+#else
+#define VT8500_CONSOLE	NULL
+#endif
+
+#ifdef CONFIG_CONSOLE_POLL
+static int vt8500_get_poll_char(struct uart_port *port)
+{
+	unsigned int status = vt8500_read(port, VT8500_URFIDX);
+
+	if (!(status & 0x1f00))
+		return NO_POLL_CHAR;
+
+	return vt8500_read(port, VT8500_RXFIFO) & 0xff;
+}
+
+static void vt8500_put_poll_char(struct uart_port *port, unsigned char c)
+{
+	unsigned int status, tmout = 10000;
+
+	do {
+		status = vt8500_read(port, VT8500_URFIDX);
+
+		if (--tmout == 0)
+			break;
+		udelay(1);
+	} while (status & 0x10);
+
+	vt8500_write(port, c, VT8500_TXFIFO);
+}
+#endif
+
+static struct uart_ops vt8500_uart_pops = {
+	.tx_empty	= vt8500_tx_empty,
+	.set_mctrl	= vt8500_set_mctrl,
+	.get_mctrl	= vt8500_get_mctrl,
+	.stop_tx	= vt8500_stop_tx,
+	.start_tx	= vt8500_start_tx,
+	.stop_rx	= vt8500_stop_rx,
+	.enable_ms	= vt8500_enable_ms,
+	.break_ctl	= vt8500_break_ctl,
+	.startup	= vt8500_startup,
+	.shutdown	= vt8500_shutdown,
+	.set_termios	= vt8500_set_termios,
+	.type		= vt8500_type,
+	.release_port	= vt8500_release_port,
+	.request_port	= vt8500_request_port,
+	.config_port	= vt8500_config_port,
+	.verify_port	= vt8500_verify_port,
+#ifdef CONFIG_CONSOLE_POLL
+	.poll_get_char	= vt8500_get_poll_char,
+	.poll_put_char	= vt8500_put_poll_char,
+#endif
+};
+
+static struct uart_driver vt8500_uart_driver = {
+	.owner		= THIS_MODULE,
+	.driver_name	= "vt8500_serial",
+	.dev_name	= "ttyWMT",
+	.nr		= 6,
+	.cons		= VT8500_CONSOLE,
+};
+
+static unsigned int vt8500_flags; /* none required so far */
+static unsigned int wm8880_flags = VT8500_HAS_SWRTSCTS_SWITCH;
+
+static const struct of_device_id wmt_dt_ids[] = {
+	{ .compatible = "via,vt8500-uart", .data = &vt8500_flags},
+	{ .compatible = "wm,wm8880-uart", .data = &wm8880_flags},
+	{}
+};
+
+static int vt8500_serial_probe(struct platform_device *pdev)
+{
+	struct vt8500_port *vt8500_port;
+	struct resource *mmres, *irqres;
+	struct device_node *np = pdev->dev.of_node;
+	const struct of_device_id *match;
+	const unsigned int *flags;
+	int ret;
+	int port;
+
+	match = of_match_device(wmt_dt_ids, &pdev->dev);
+	if (!match)
+		return -EINVAL;
+
+	flags = match->data;
+
+	mmres = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	irqres = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	if (!mmres || !irqres)
+		return -ENODEV;
+
+	if (np) {
+		port = of_alias_get_id(np, "serial");
+		if (port >= VT8500_MAX_PORTS)
+			port = -1;
+	} else {
+		port = -1;
+	}
+
+	if (port < 0) {
+		/* calculate the port id */
+		port = find_first_zero_bit(&vt8500_ports_in_use,
+					sizeof(vt8500_ports_in_use));
+	}
+
+	if (port >= VT8500_MAX_PORTS)
+		return -ENODEV;
+
+	/* reserve the port id */
+	if (test_and_set_bit(port, &vt8500_ports_in_use)) {
+		/* port already in use - shouldn't really happen */
+		return -EBUSY;
+	}
+
+	vt8500_port = devm_kzalloc(&pdev->dev, sizeof(struct vt8500_port),
+				   GFP_KERNEL);
+	if (!vt8500_port)
+		return -ENOMEM;
+
+	vt8500_port->uart.membase = devm_ioremap_resource(&pdev->dev, mmres);
+	if (IS_ERR(vt8500_port->uart.membase))
+		return PTR_ERR(vt8500_port->uart.membase);
+
+	vt8500_port->clk = of_clk_get(pdev->dev.of_node, 0);
+	if (IS_ERR(vt8500_port->clk)) {
+		dev_err(&pdev->dev, "failed to get clock\n");
+		return  -EINVAL;
+	}
+
+	ret = clk_prepare_enable(vt8500_port->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to enable clock\n");
+		return ret;
+	}
+
+	vt8500_port->vt8500_uart_flags = *flags;
+	vt8500_port->clk_predivisor = DIV_ROUND_CLOSEST(
+					clk_get_rate(vt8500_port->clk),
+					VT8500_RECOMMENDED_CLK
+				      );
+	vt8500_port->uart.type = PORT_VT8500;
+	vt8500_port->uart.iotype = UPIO_MEM;
+	vt8500_port->uart.mapbase = mmres->start;
+	vt8500_port->uart.irq = irqres->start;
+	vt8500_port->uart.fifosize = 16;
+	vt8500_port->uart.ops = &vt8500_uart_pops;
+	vt8500_port->uart.line = port;
+	vt8500_port->uart.dev = &pdev->dev;
+	vt8500_port->uart.flags = UPF_IOREMAP | UPF_BOOT_AUTOCONF;
+
+	/* Serial core uses the magic "16" everywhere - adjust for it */
+	vt8500_port->uart.uartclk = 16 * clk_get_rate(vt8500_port->clk) /
+					vt8500_port->clk_predivisor /
+					VT8500_OVERSAMPLING_DIVISOR;
+
+	snprintf(vt8500_port->name, sizeof(vt8500_port->name),
+		 "VT8500 UART%d", pdev->id);
+
+	vt8500_uart_ports[port] = vt8500_port;
+
+	uart_add_one_port(&vt8500_uart_driver, &vt8500_port->uart);
+
+	platform_set_drvdata(pdev, vt8500_port);
+
+	return 0;
+}
+
+static int vt8500_serial_remove(struct platform_device *pdev)
+{
+	struct vt8500_port *vt8500_port = platform_get_drvdata(pdev);
+
+	clk_disable_unprepare(vt8500_port->clk);
+	uart_remove_one_port(&vt8500_uart_driver, &vt8500_port->uart);
+
+	return 0;
+}
+
+static struct platform_driver vt8500_platform_driver = {
+	.probe  = vt8500_serial_probe,
+	.remove = vt8500_serial_remove,
+	.driver = {
+		.name = "vt8500_serial",
+		.of_match_table = wmt_dt_ids,
+	},
+};
+
+static int __init vt8500_serial_init(void)
+{
+	int ret;
+
+	ret = uart_register_driver(&vt8500_uart_driver);
+	if (unlikely(ret))
+		return ret;
+
+	ret = platform_driver_register(&vt8500_platform_driver);
+
+	if (unlikely(ret))
+		uart_unregister_driver(&vt8500_uart_driver);
+
+	return ret;
+}
+
+static void __exit vt8500_serial_exit(void)
+{
+#ifdef CONFIG_SERIAL_VT8500_CONSOLE
+	unregister_console(&vt8500_console);
+#endif
+	platform_driver_unregister(&vt8500_platform_driver);
+	uart_unregister_driver(&vt8500_uart_driver);
+}
+
+module_init(vt8500_serial_init);
+module_exit(vt8500_serial_exit);
+
+MODULE_AUTHOR("Alexey Charkov <alchark@gmail.com>");
+MODULE_DESCRIPTION("Driver for vt8500 serial device");
+MODULE_LICENSE("GPL v2");