Add the rt linux 4.1.3-rt3 as base
[kvmfornfv.git] / kernel / drivers / tty / serial / vt8500_serial.c
diff --git a/kernel/drivers/tty/serial/vt8500_serial.c b/kernel/drivers/tty/serial/vt8500_serial.c
new file mode 100644 (file)
index 0000000..4079ec5
--- /dev/null
@@ -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");