serial: Add support for UART on VIA VT8500 and compatibles

This adds a driver for the serial ports found in VIA and WonderMedia
Systems-on-Chip. Interrupt-driven FIFO operation is implemented.
The hardware also supports pure register-based operation (which is
slower) and DMA-based FIFO operation. As the FIFOs are only 16 bytes
long, DMA operation is probably not worth the hassle.

Signed-off-by: Alexey Charkov <alchark@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

4 files changed, 662 insertions, 0 deletions

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 0b9cc17b380b..388e37132cc9 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -1381,6 +1381,16 @@ config SERIAL_MSM_CONSOLE
         depends on SERIAL_MSM=y
         select SERIAL_CORE_CONSOLE
 
+config SERIAL_VT8500
+        bool "VIA VT8500 on-chip serial port support"
+        depends on ARM && ARCH_VT8500
+        select SERIAL_CORE
+
+config SERIAL_VT8500_CONSOLE
+        bool "VIA VT8500 serial console support"
+        depends on SERIAL_VT8500=y
+        select SERIAL_CORE_CONSOLE
+
 config SERIAL_NETX
         tristate "NetX serial port support"
         depends on ARM && ARCH_NETX
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 783638b10698..a5e2264b2a80 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -86,6 +86,7 @@ obj-$(CONFIG_SERIAL_TIMBERDALE)	+= timbuart.o
 obj-$(CONFIG_SERIAL_GRLIB_GAISLER_APBUART) += apbuart.o
 obj-$(CONFIG_SERIAL_ALTERA_JTAGUART) += altera_jtaguart.o
 obj-$(CONFIG_SERIAL_ALTERA_UART) += altera_uart.o
+obj-$(CONFIG_SERIAL_VT8500) += vt8500_serial.o
 obj-$(CONFIG_SERIAL_MRST_MAX3110)       += mrst_max3110.o
 obj-$(CONFIG_SERIAL_MFD_HSU)    += mfd.o
 obj-$(CONFIG_SERIAL_OMAP) += omap-serial.o
diff --git a/drivers/serial/vt8500_serial.c b/drivers/serial/vt8500_serial.c
new file mode 100644
index 000000000000..322bf56c0d89
--- /dev/null
+++ b/drivers/serial/vt8500_serial.c
@@ -0,0 +1,648 @@
+/*
+ * drivers/serial/vt8500_serial.c
+ *
+ * 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/platform_device.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)
+
+struct vt8500_port {
+        struct uart_port        uart;
+        char                    name[16];
+        struct clk              *clk;
+        unsigned int            ier;
+};
+
+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_struct *tty = tty_port_tty_get(&port->state->port);
+        if (!tty) {
+                /* Discard data: no tty available */
+                int count = (vt8500_read(port, VT8500_URFIDX) & 0x1f00) >> 8;
+                u16 ch;
+                while (count--)
+                        ch = readw(port->membase + VT8500_RXFIFO);
+                return;
+        }
+
+        /*
+         * Handle overrun
+         */
+        if ((vt8500_read(port, VT8500_URISR) & RXOVER)) {
+                port->icount.overrun++;
+                tty_insert_flip_char(tty, 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(tty, c, flag);
+        }
+
+        tty_flip_buffer_push(tty);
+        tty_kref_put(tty);
+}
+
+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)
+{
+}
+
+static void vt8500_break_ctl(struct uart_port *port, int break_ctl)
+{
+        if (break_ctl)
+                vt8500_write(port, vt8500_read(port, VT8500_URLCR) | (1 << 9),
+                             VT8500_URLCR);
+}
+
+static int vt8500_set_baud_rate(struct uart_port *port, unsigned int baud)
+{
+        unsigned long div;
+        unsigned int loops = 1000;
+
+        div = vt8500_read(port, VT8500_URDIV) & ~(0x3ff);
+
+        if (unlikely((baud < 900) || (baud > 921600)))
+                div |= 7;
+        else
+                div |= (921600 / baud) - 1;
+
+        while ((vt8500_read(port, VT8500_URUSR) & (1 << 5)) && --loops)
+                cpu_relax();
+        vt8500_write(port, div, VT8500_URDIV);
+
+        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 &= ~((1 << 5) | (1 << 4));
+        if (termios->c_cflag & PARENB) {
+                lcr |= (1 << 4);
+                termios->c_cflag &= ~CMSPAR;
+                if (termios->c_cflag & PARODD)
+                        lcr |= (1 << 5);
+        }
+
+        /* calculate bits per char */
+        lcr &= ~(1 << 2);
+        switch (termios->c_cflag & CSIZE) {
+        case CS7:
+                break;
+        case CS8:
+        default:
+                lcr |= (1 << 2);
+                termios->c_cflag &= ~CSIZE;
+                termios->c_cflag |= CS8;
+                break;
+        }
+
+        /* calculate stop bits */
+        lcr &= ~(1 << 3);
+        if (termios->c_cflag & CSTOPB)
+                lcr |= (1 << 3);
+
+        /* 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[4];
+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
+
+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,
+};
+
+static struct uart_driver vt8500_uart_driver = {
+        .owner          = THIS_MODULE,
+        .driver_name    = "vt8500_serial",
+        .dev_name       = "ttyWMT",
+        .nr             = 6,
+        .cons           = VT8500_CONSOLE,
+};
+
+static int __init vt8500_serial_probe(struct platform_device *pdev)
+{
+        struct vt8500_port *vt8500_port;
+        struct resource *mmres, *irqres;
+        int ret;
+
+        mmres = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        irqres = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+        if (!mmres || !irqres)
+                return -ENODEV;
+
+        vt8500_port = kzalloc(sizeof(struct vt8500_port), GFP_KERNEL);
+        if (!vt8500_port)
+                return -ENOMEM;
+
+        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 = pdev->id;
+        vt8500_port->uart.dev = &pdev->dev;
+        vt8500_port->uart.flags = UPF_IOREMAP | UPF_BOOT_AUTOCONF;
+        vt8500_port->uart.uartclk = 24000000;
+
+        snprintf(vt8500_port->name, sizeof(vt8500_port->name),
+                 "VT8500 UART%d", pdev->id);
+
+        vt8500_port->uart.membase = ioremap(mmres->start,
+                                            mmres->end - mmres->start + 1);
+        if (!vt8500_port->uart.membase) {
+                ret = -ENOMEM;
+                goto err;
+        }
+
+        vt8500_uart_ports[pdev->id] = vt8500_port;
+
+        uart_add_one_port(&vt8500_uart_driver, &vt8500_port->uart);
+
+        platform_set_drvdata(pdev, vt8500_port);
+
+        return 0;
+
+err:
+        kfree(vt8500_port);
+        return ret;
+}
+
+static int __devexit vt8500_serial_remove(struct platform_device *pdev)
+{
+        struct vt8500_port *vt8500_port = platform_get_drvdata(pdev);
+
+        platform_set_drvdata(pdev, NULL);
+        uart_remove_one_port(&vt8500_uart_driver, &vt8500_port->uart);
+        kfree(vt8500_port);
+
+        return 0;
+}
+
+static struct platform_driver vt8500_platform_driver = {
+        .probe  = vt8500_serial_probe,
+        .remove = vt8500_serial_remove,
+        .driver = {
+                .name = "vt8500_serial",
+                .owner = THIS_MODULE,
+        },
+};
+
+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");
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 212eb4c67797..41603d690433 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -199,6 +199,9 @@
 /* TI OMAP-UART */
 #define PORT_OMAP       96
 
+/* VIA VT8500 SoC */
+#define PORT_VT8500     97
+
 #ifdef __KERNEL__
 
 #include <linux/compiler.h>