mrst_max3110: add UART driver for Max3110 on Moorestown

This driver enable the max3110 device, it can be used as
a system console. the IRQ needs be enabled if user want a
better performance. MRST max3110 works in 3.684MHz clock,
which supports 230400 as its maximum rate.

Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

4 files changed, 921 insertions, 0 deletions

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index e437ce8c1748..964634e79c16 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -690,6 +690,23 @@ config SERIAL_SA1100_CONSOLE
           your boot loader (lilo or loadlin) about how to pass options to the
           kernel at boot time.)
 
+config SERIAL_MRST_MAX3110
+        tristate "SPI UART driver for Max3110"
+        depends on SPI_DW_PCI
+        select SERIAL_CORE
+        select SERIAL_CORE_CONSOLE
+        help
+          This is the UART protocol driver for the MAX3110 device on
+          the Intel Moorestown platform. On other systems use the max3100
+          driver.
+
+config MRST_MAX3110_IRQ
+        boolean "Enable GPIO IRQ for Max3110 over Moorestown"
+        default n
+        depends on SERIAL_MRST_MAX3110 && GPIO_LANGWELL
+        help
+          This has to be enabled after Moorestown GPIO driver is loaded
+
 config SERIAL_BFIN
         tristate "Blackfin serial port support"
         depends on BLACKFIN
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 208a85572c32..a5edb49c7303 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -84,3 +84,4 @@ 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_MRST_MAX3110)       += mrst_max3110.o
diff --git a/drivers/serial/mrst_max3110.c b/drivers/serial/mrst_max3110.c
new file mode 100644
index 000000000000..273e7cbe74cd
--- /dev/null
+++ b/drivers/serial/mrst_max3110.c
@@ -0,0 +1,844 @@
+/*
+ *  max3110.c - spi uart protocol driver for Maxim 3110 on Moorestown
+ *
+ *  Copyright (C) Intel 2008 Feng Tang <feng.tang@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * Note:
+ * 1. From Max3110 spec, the Rx FIFO has 8 words, while the Tx FIFO only has
+ *    1 word. If SPI master controller doesn't support sclk frequency change,
+ *    then the char need be sent out one by one with some delay
+ *
+ * 2. Currently only RX availabe interrrupt is used, no need for waiting TXE
+ *    interrupt for a low speed UART device
+ */
+
+#include <linux/module.h>
+#include <linux/ioport.h>
+#include <linux/init.h>
+#include <linux/console.h>
+#include <linux/sysrq.h>
+#include <linux/platform_device.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/serial_core.h>
+#include <linux/serial_reg.h>
+
+#include <linux/kthread.h>
+#include <linux/delay.h>
+#include <asm/atomic.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/dw_spi.h>
+
+#include "mrst_max3110.h"
+
+#define PR_FMT  "mrst_max3110: "
+
+struct uart_max3110 {
+        struct uart_port port;
+        struct spi_device *spi;
+        char *name;
+
+        wait_queue_head_t wq;
+        struct task_struct *main_thread;
+        struct task_struct *read_thread;
+        int mthread_up;
+        spinlock_t lock;
+
+        u32 baud;
+        u16 cur_conf;
+        u8 clock;
+        u8 parity, word_7bits;
+
+        atomic_t uart_tx_need;
+
+        /* console related */
+        struct circ_buf con_xmit;
+        atomic_t con_tx_need;
+
+        /* irq related */
+        u16 irq;
+        atomic_t irq_pending;
+};
+
+/* global data structure, may need be removed */
+struct uart_max3110 *pmax;
+static inline void receive_char(struct uart_max3110 *max, u8 ch);
+static void receive_chars(struct uart_max3110 *max,
+                                unsigned char *str, int len);
+static int max3110_read_multi(struct uart_max3110 *max, int len, u8 *buf);
+static void max3110_console_receive(struct uart_max3110 *max);
+
+int max3110_write_then_read(struct uart_max3110 *max,
+                const u8 *txbuf, u8 *rxbuf, unsigned len, int always_fast)
+{
+        struct spi_device *spi = max->spi;
+        struct spi_message      message;
+        struct spi_transfer     x;
+        int ret;
+
+        if (!txbuf || !rxbuf)
+                return -EINVAL;
+
+        spi_message_init(&message);
+        memset(&x, 0, sizeof x);
+        x.len = len;
+        x.tx_buf = txbuf;
+        x.rx_buf = rxbuf;
+        spi_message_add_tail(&x, &message);
+
+        if (always_fast)
+                x.speed_hz = 3125000;
+        else if (max->baud)
+                x.speed_hz = max->baud;
+
+        /* Do the i/o */
+        ret = spi_sync(spi, &message);
+        return ret;
+}
+
+/* Write a u16 to the device, and return one u16 read back */
+int max3110_out(struct uart_max3110 *max, const u16 out)
+{
+        u16 tmp;
+        int ret;
+
+        ret = max3110_write_then_read(max, (u8 *)&out, (u8 *)&tmp, 2, 1);
+        if (ret)
+                return ret;
+
+        /* If some valid data is read back */
+        if (tmp & MAX3110_READ_DATA_AVAILABLE)
+                receive_char(max, (tmp & 0xff));
+
+        return ret;
+}
+
+#define MAX_READ_LEN    20
+/*
+ * This is usually used to read data from SPIC RX FIFO, which doesn't
+ * need any delay like flushing character out. It returns how many
+ * valide bytes are read back
+ */
+static int max3110_read_multi(struct uart_max3110 *max, int len, u8 *buf)
+{
+        u16 out[MAX_READ_LEN], in[MAX_READ_LEN];
+        u8 *pbuf, valid_str[MAX_READ_LEN];
+        int i, j, bytelen;
+
+        if (len > MAX_READ_LEN) {
+                pr_err(PR_FMT "read len %d is too large\n", len);
+                return 0;
+        }
+
+        bytelen = len * 2;
+        memset(out, 0, bytelen);
+        memset(in, 0, bytelen);
+
+        if (max3110_write_then_read(max, (u8 *)out, (u8 *)in, bytelen, 1))
+                return 0;
+
+        /* If caller don't provide a buffer, then handle received char */
+        pbuf = buf ? buf : valid_str;
+
+        for (i = 0, j = 0; i < len; i++) {
+                if (in[i] & MAX3110_READ_DATA_AVAILABLE)
+                        pbuf[j++] = (u8)(in[i] & 0xff);
+        }
+
+        if (j && (pbuf == valid_str))
+                receive_chars(max, valid_str, j);
+
+        return j;
+}
+
+static void serial_m3110_con_putchar(struct uart_port *port, int ch)
+{
+        struct uart_max3110 *max =
+                container_of(port, struct uart_max3110, port);
+        struct circ_buf *xmit = &max->con_xmit;
+
+        if (uart_circ_chars_free(xmit)) {
+                xmit->buf[xmit->head] = (char)ch;
+                xmit->head = (xmit->head + 1) & (PAGE_SIZE - 1);
+        }
+
+        if (!atomic_read(&max->con_tx_need)) {
+                atomic_set(&max->con_tx_need, 1);
+                wake_up_process(max->main_thread);
+        }
+}
+
+/*
+ * Print a string to the serial port trying not to disturb
+ * any possible real use of the port...
+ *
+ *      The console_lock must be held when we get here.
+ */
+static void serial_m3110_con_write(struct console *co,
+                                const char *s, unsigned int count)
+{
+        if (!pmax)
+                return;
+
+        uart_console_write(&pmax->port, s, count, serial_m3110_con_putchar);
+}
+
+static int __init
+serial_m3110_con_setup(struct console *co, char *options)
+{
+        struct uart_max3110 *max = pmax;
+        int baud = 115200;
+        int bits = 8;
+        int parity = 'n';
+        int flow = 'n';
+
+        pr_info(PR_FMT "setting up console\n");
+
+        if (!max) {
+                pr_err(PR_FMT "pmax is NULL, return");
+                return -ENODEV;
+        }
+
+        if (options)
+                uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+        return uart_set_options(&max->port, co, baud, parity, bits, flow);
+}
+
+static struct tty_driver *serial_m3110_con_device(struct console *co,
+                                                        int *index)
+{
+        struct uart_driver *p = co->data;
+        *index = co->index;
+        return p->tty_driver;
+}
+
+static struct uart_driver serial_m3110_reg;
+static struct console serial_m3110_console = {
+        .name           = "ttyS",
+        .write          = serial_m3110_con_write,
+        .device         = serial_m3110_con_device,
+        .setup          = serial_m3110_con_setup,
+        .flags          = CON_PRINTBUFFER,
+        .index          = -1,
+        .data           = &serial_m3110_reg,
+};
+
+#define MRST_CONSOLE    (&serial_m3110_console)
+
+static unsigned int serial_m3110_tx_empty(struct uart_port *port)
+{
+        return 1;
+}
+
+static void serial_m3110_stop_tx(struct uart_port *port)
+{
+        return;
+}
+
+/* stop_rx will be called in spin_lock env */
+static void serial_m3110_stop_rx(struct uart_port *port)
+{
+        return;
+}
+
+#define WORDS_PER_XFER  128
+static inline void send_circ_buf(struct uart_max3110 *max,
+                                struct circ_buf *xmit)
+{
+        int len, left = 0;
+        u16 obuf[WORDS_PER_XFER], ibuf[WORDS_PER_XFER];
+        u8 valid_str[WORDS_PER_XFER];
+        int i, j;
+
+        while (!uart_circ_empty(xmit)) {
+                left = uart_circ_chars_pending(xmit);
+                while (left) {
+                        len = (left >= WORDS_PER_XFER) ? WORDS_PER_XFER : left;
+
+                        memset(obuf, 0, len * 2);
+                        memset(ibuf, 0, len * 2);
+                        for (i = 0; i < len; i++) {
+                                obuf[i] = (u8)xmit->buf[xmit->tail] | WD_TAG;
+                                xmit->tail = (xmit->tail + 1) &
+                                                (UART_XMIT_SIZE - 1);
+                        }
+                        max3110_write_then_read(max, (u8 *)obuf,
+                                                (u8 *)ibuf, len * 2, 0);
+
+                        for (i = 0, j = 0; i < len; i++) {
+                                if (ibuf[i] & MAX3110_READ_DATA_AVAILABLE)
+                                        valid_str[j++] = (u8)(ibuf[i] & 0xff);
+                        }
+
+                        if (j)
+                                receive_chars(max, valid_str, j);
+
+                        max->port.icount.tx += len;
+                        left -= len;
+                }
+        }
+}
+
+static void transmit_char(struct uart_max3110 *max)
+{
+        struct uart_port *port = &max->port;
+        struct circ_buf *xmit = &port->state->xmit;
+
+        if (uart_circ_empty(xmit) || uart_tx_stopped(port))
+                return;
+
+        send_circ_buf(max, xmit);
+
+        if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+                uart_write_wakeup(port);
+
+        if (uart_circ_empty(xmit))
+                serial_m3110_stop_tx(port);
+}
+
+/* This will be called by uart_write() and tty_write, can't
+ * go to sleep */
+static void serial_m3110_start_tx(struct uart_port *port)
+{
+        struct uart_max3110 *max =
+                container_of(port, struct uart_max3110, port);
+
+        if (!atomic_read(&max->uart_tx_need)) {
+                atomic_set(&max->uart_tx_need, 1);
+                wake_up_process(max->main_thread);
+        }
+}
+
+static void receive_chars(struct uart_max3110 *max, unsigned char *str, int len)
+{
+        struct uart_port *port = &max->port;
+        struct tty_struct *tty;
+        int usable;
+
+        /* If uart is not opened, just return */
+        if (!port->state)
+                return;
+
+        tty = port->state->port.tty;
+        if (!tty)
+                return; /* receive some char before the tty is opened */
+
+        while (len) {
+                usable = tty_buffer_request_room(tty, len);
+                if (usable) {
+                        tty_insert_flip_string(tty, str, usable);
+                        str += usable;
+                        port->icount.rx += usable;
+                        tty_flip_buffer_push(tty);
+                }
+                len -= usable;
+        }
+}
+
+static inline void receive_char(struct uart_max3110 *max, u8 ch)
+{
+        receive_chars(max, &ch, 1);
+}
+
+static void max3110_console_receive(struct uart_max3110 *max)
+{
+        int loop = 1, num, total = 0;
+        u8 recv_buf[512], *pbuf;
+
+        pbuf = recv_buf;
+        do {
+                num = max3110_read_multi(max, 8, pbuf);
+
+                if (num) {
+                        loop = 10;
+                        pbuf += num;
+                        total += num;
+
+                        if (total >= 500) {
+                                receive_chars(max, recv_buf, total);
+                                pbuf = recv_buf;
+                                total = 0;
+                        }
+                }
+        } while (--loop);
+
+        if (total)
+                receive_chars(max, recv_buf, total);
+}
+
+static int max3110_main_thread(void *_max)
+{
+        struct uart_max3110 *max = _max;
+        wait_queue_head_t *wq = &max->wq;
+        int ret = 0;
+        struct circ_buf *xmit = &max->con_xmit;
+
+        init_waitqueue_head(wq);
+        pr_info(PR_FMT "start main thread\n");
+
+        do {
+                wait_event_interruptible(*wq, (atomic_read(&max->irq_pending) ||
+                                               atomic_read(&max->con_tx_need) ||
+                                             atomic_read(&max->uart_tx_need)) ||
+                                             kthread_should_stop());
+                max->mthread_up = 1;
+
+#ifdef CONFIG_MRST_MAX3110_IRQ
+                if (atomic_read(&max->irq_pending)) {
+                        max3110_console_receive(max);
+                        atomic_set(&max->irq_pending, 0);
+                }
+#endif
+
+                /* first handle console output */
+                if (atomic_read(&max->con_tx_need)) {
+                        send_circ_buf(max, xmit);
+                        atomic_set(&max->con_tx_need, 0);
+                }
+
+                /* handle uart output */
+                if (atomic_read(&max->uart_tx_need)) {
+                        transmit_char(max);
+                        atomic_set(&max->uart_tx_need, 0);
+                }
+                max->mthread_up = 0;
+        } while (!kthread_should_stop());
+
+        return ret;
+}
+
+#ifdef CONFIG_MRST_MAX3110_IRQ
+static irqreturn_t serial_m3110_irq(int irq, void *dev_id)
+{
+        struct uart_max3110 *max = dev_id;
+
+        /* max3110's irq is a falling edge, not level triggered,
+         * so no need to disable the irq */
+        if (!atomic_read(&max->irq_pending)) {
+                atomic_inc(&max->irq_pending);
+                wake_up_process(max->main_thread);
+        }
+        return IRQ_HANDLED;
+}
+#else
+/* if don't use RX IRQ, then need a thread to polling read */
+static int max3110_read_thread(void *_max)
+{
+        struct uart_max3110 *max = _max;
+
+        pr_info(PR_FMT "start read thread\n");
+        do {
+                if (!max->mthread_up)
+                        max3110_console_receive(max);
+
+                set_current_state(TASK_INTERRUPTIBLE);
+                schedule_timeout(HZ / 20);
+        } while (!kthread_should_stop());
+
+        return 0;
+}
+#endif
+
+static int serial_m3110_startup(struct uart_port *port)
+{
+        struct uart_max3110 *max =
+                container_of(port, struct uart_max3110, port);
+        u16 config = 0;
+        int ret = 0;
+
+        if (port->line != 0)
+                pr_err(PR_FMT "uart port startup failed\n");
+
+        /* firstly disable all IRQ and config it to 115200, 8n1 */
+        config = WC_TAG | WC_FIFO_ENABLE
+                        | WC_1_STOPBITS
+                        | WC_8BIT_WORD
+                        | WC_BAUD_DR2;
+        ret = max3110_out(max, config);
+
+        /* as we use thread to handle tx/rx, need set low latency */
+        port->state->port.tty->low_latency = 1;
+
+#ifdef CONFIG_MRST_MAX3110_IRQ
+        ret = request_irq(max->irq, serial_m3110_irq,
+                                IRQ_TYPE_EDGE_FALLING, "max3110", max);
+        if (ret)
+                return ret;
+
+        /* enable RX IRQ only */
+        config |= WC_RXA_IRQ_ENABLE;
+        max3110_out(max, config);
+#else
+        /* if IRQ is disabled, start a read thread for input data */
+        max->read_thread =
+                kthread_run(max3110_read_thread, max, "max3110_read");
+#endif
+
+        max->cur_conf = config;
+        return 0;
+}
+
+static void serial_m3110_shutdown(struct uart_port *port)
+{
+        struct uart_max3110 *max =
+                container_of(port, struct uart_max3110, port);
+        u16 config;
+
+        if (max->read_thread) {
+                kthread_stop(max->read_thread);
+                max->read_thread = NULL;
+        }
+
+#ifdef CONFIG_MRST_MAX3110_IRQ
+        free_irq(max->irq, max);
+#endif
+
+        /* Disable interrupts from this port */
+        config = WC_TAG | WC_SW_SHDI;
+        max3110_out(max, config);
+}
+
+static void serial_m3110_release_port(struct uart_port *port)
+{
+}
+
+static int serial_m3110_request_port(struct uart_port *port)
+{
+        return 0;
+}
+
+static void serial_m3110_config_port(struct uart_port *port, int flags)
+{
+        /* give it fake type */
+        port->type = PORT_PXA;
+}
+
+static int
+serial_m3110_verify_port(struct uart_port *port, struct serial_struct *ser)
+{
+        /* we don't want the core code to modify any port params */
+        return -EINVAL;
+}
+
+
+static const char *serial_m3110_type(struct uart_port *port)
+{
+        struct uart_max3110 *max =
+                container_of(port, struct uart_max3110, port);
+        return max->name;
+}
+
+static void
+serial_m3110_set_termios(struct uart_port *port, struct ktermios *termios,
+                       struct ktermios *old)
+{
+        struct uart_max3110 *max =
+                container_of(port, struct uart_max3110, port);
+        unsigned char cval;
+        unsigned int baud, parity = 0;
+        int clk_div = -1;
+        u16 new_conf = max->cur_conf;
+
+        switch (termios->c_cflag & CSIZE) {
+        case CS7:
+                cval = UART_LCR_WLEN7;
+                new_conf |= WC_7BIT_WORD;
+                break;
+        default:
+        case CS8:
+                cval = UART_LCR_WLEN8;
+                new_conf |= WC_8BIT_WORD;
+                break;
+        }
+
+        baud = uart_get_baud_rate(port, termios, old, 0, 230400);
+
+        /* first calc the div for 1.8MHZ clock case */
+        switch (baud) {
+        case 300:
+                clk_div = WC_BAUD_DR384;
+                break;
+        case 600:
+                clk_div = WC_BAUD_DR192;
+                break;
+        case 1200:
+                clk_div = WC_BAUD_DR96;
+                break;
+        case 2400:
+                clk_div = WC_BAUD_DR48;
+                break;
+        case 4800:
+                clk_div = WC_BAUD_DR24;
+                break;
+        case 9600:
+                clk_div = WC_BAUD_DR12;
+                break;
+        case 19200:
+                clk_div = WC_BAUD_DR6;
+                break;
+        case 38400:
+                clk_div = WC_BAUD_DR3;
+                break;
+        case 57600:
+                clk_div = WC_BAUD_DR2;
+                break;
+        case 115200:
+                clk_div = WC_BAUD_DR1;
+                break;
+        case 230400:
+                if (max->clock & MAX3110_HIGH_CLK)
+                        break;
+        default:
+                /* pick the previous baud rate */
+                baud = max->baud;
+                clk_div = max->cur_conf & WC_BAUD_DIV_MASK;
+                tty_termios_encode_baud_rate(termios, baud, baud);
+        }
+
+        if (max->clock & MAX3110_HIGH_CLK) {
+                clk_div += 1;
+                /* high clk version max3110 doesn't support B300 */
+                if (baud == 300)
+                        baud = 600;
+                if (baud == 230400)
+                        clk_div = WC_BAUD_DR1;
+                tty_termios_encode_baud_rate(termios, baud, baud);
+        }
+
+        new_conf = (new_conf & ~WC_BAUD_DIV_MASK) | clk_div;
+        if (termios->c_cflag & CSTOPB)
+                new_conf |= WC_2_STOPBITS;
+        else
+                new_conf &= ~WC_2_STOPBITS;
+
+        if (termios->c_cflag & PARENB) {
+                new_conf |= WC_PARITY_ENABLE;
+                parity |= UART_LCR_PARITY;
+        } else
+                new_conf &= ~WC_PARITY_ENABLE;
+
+        if (!(termios->c_cflag & PARODD))
+                parity |= UART_LCR_EPAR;
+        max->parity = parity;
+
+        uart_update_timeout(port, termios->c_cflag, baud);
+
+        new_conf |= WC_TAG;
+        if (new_conf != max->cur_conf) {
+                max3110_out(max, new_conf);
+                max->cur_conf = new_conf;
+                max->baud = baud;
+        }
+}
+
+/* don't handle hw handshaking */
+static unsigned int serial_m3110_get_mctrl(struct uart_port *port)
+{
+        return TIOCM_DSR | TIOCM_CAR | TIOCM_DSR;
+}
+
+static void serial_m3110_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+}
+
+static void serial_m3110_break_ctl(struct uart_port *port, int break_state)
+{
+}
+
+static void serial_m3110_pm(struct uart_port *port, unsigned int state,
+                        unsigned int oldstate)
+{
+}
+
+static void serial_m3110_enable_ms(struct uart_port *port)
+{
+}
+
+struct uart_ops serial_m3110_ops = {
+        .tx_empty       = serial_m3110_tx_empty,
+        .set_mctrl      = serial_m3110_set_mctrl,
+        .get_mctrl      = serial_m3110_get_mctrl,
+        .stop_tx        = serial_m3110_stop_tx,
+        .start_tx       = serial_m3110_start_tx,
+        .stop_rx        = serial_m3110_stop_rx,
+        .enable_ms      = serial_m3110_enable_ms,
+        .break_ctl      = serial_m3110_break_ctl,
+        .startup        = serial_m3110_startup,
+        .shutdown       = serial_m3110_shutdown,
+        .set_termios    = serial_m3110_set_termios,     /* must have */
+        .pm             = serial_m3110_pm,
+        .type           = serial_m3110_type,
+        .release_port   = serial_m3110_release_port,
+        .request_port   = serial_m3110_request_port,
+        .config_port    = serial_m3110_config_port,
+        .verify_port    = serial_m3110_verify_port,
+};
+
+static struct uart_driver serial_m3110_reg = {
+        .owner          = THIS_MODULE,
+        .driver_name    = "MRST serial",
+        .dev_name       = "ttyS",
+        .major          = TTY_MAJOR,
+        .minor          = 64,
+        .nr             = 1,
+        .cons           = MRST_CONSOLE,
+};
+
+static int serial_m3110_suspend(struct spi_device *spi, pm_message_t state)
+{
+        return 0;
+}
+
+static int serial_m3110_resume(struct spi_device *spi)
+{
+        return 0;
+}
+
+static struct dw_spi_chip spi0_uart = {
+        .poll_mode = 1,
+        .enable_dma = 0,
+        .type = SPI_FRF_SPI,
+};
+
+static int serial_m3110_probe(struct spi_device *spi)
+{
+        struct uart_max3110 *max;
+        int ret;
+        unsigned char *buffer;
+
+        max = kzalloc(sizeof(*max), GFP_KERNEL);
+        if (!max)
+                return -ENOMEM;
+
+        /* set spi info */
+        spi->mode = SPI_MODE_0;
+        spi->bits_per_word = 16;
+        max->clock = MAX3110_HIGH_CLK;
+        spi->controller_data = &spi0_uart;
+
+        spi_setup(spi);
+
+        max->port.type = PORT_PXA;      /* need apply for a max3110 type */
+        max->port.fifosize = 2;         /* only have 16b buffer */
+        max->port.ops = &serial_m3110_ops;
+        max->port.line = 0;
+        max->port.dev = &spi->dev;
+        max->port.uartclk = 115200;
+
+        max->spi = spi;
+        max->name = spi->modalias;      /* use spi name as the name */
+        max->irq = (u16)spi->irq;
+
+        spin_lock_init(&max->lock);
+
+        max->word_7bits = 0;
+        max->parity = 0;
+        max->baud = 0;
+
+        max->cur_conf = 0;
+        atomic_set(&max->irq_pending, 0);
+
+        buffer = (unsigned char *)__get_free_page(GFP_KERNEL);
+        if (!buffer) {
+                ret = -ENOMEM;
+                goto err_get_page;
+        }
+        max->con_xmit.buf = (unsigned char *)buffer;
+        max->con_xmit.head = max->con_xmit.tail = 0;
+
+        max->main_thread = kthread_run(max3110_main_thread,
+                                        max, "max3110_main");
+        if (IS_ERR(max->main_thread)) {
+                ret = PTR_ERR(max->main_thread);
+                goto err_kthread;
+        }
+
+        pmax = max;
+        /* give membase a psudo value to pass serial_core's check */
+        max->port.membase = (void *)0xff110000;
+        uart_add_one_port(&serial_m3110_reg, &max->port);
+
+        return 0;
+
+err_kthread:
+        free_page((unsigned long)buffer);
+err_get_page:
+        pmax = NULL;
+        kfree(max);
+        return ret;
+}
+
+static int max3110_remove(struct spi_device *dev)
+{
+        struct uart_max3110 *max = pmax;
+
+        if (!pmax)
+                return 0;
+
+        pmax = NULL;
+        uart_remove_one_port(&serial_m3110_reg, &max->port);
+
+        free_page((unsigned long)max->con_xmit.buf);
+
+        if (max->main_thread)
+                kthread_stop(max->main_thread);
+
+        kfree(max);
+        return 0;
+}
+
+static struct spi_driver uart_max3110_driver = {
+        .driver = {
+                        .name   = "spi_max3111",
+                        .bus    = &spi_bus_type,
+                        .owner  = THIS_MODULE,
+        },
+        .probe          = serial_m3110_probe,
+        .remove         = __devexit_p(max3110_remove),
+        .suspend        = serial_m3110_suspend,
+        .resume         = serial_m3110_resume,
+};
+
+
+int __init serial_m3110_init(void)
+{
+        int ret = 0;
+
+        ret = uart_register_driver(&serial_m3110_reg);
+        if (ret)
+                return ret;
+
+        ret = spi_register_driver(&uart_max3110_driver);
+        if (ret)
+                uart_unregister_driver(&serial_m3110_reg);
+
+        return ret;
+}
+
+void __exit serial_m3110_exit(void)
+{
+        spi_unregister_driver(&uart_max3110_driver);
+        uart_unregister_driver(&serial_m3110_reg);
+}
+
+module_init(serial_m3110_init);
+module_exit(serial_m3110_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("max3110-uart");
diff --git a/drivers/serial/mrst_max3110.h b/drivers/serial/mrst_max3110.h
new file mode 100644
index 000000000000..363478acb2c3
--- /dev/null
+++ b/drivers/serial/mrst_max3110.h
@@ -0,0 +1,59 @@
+#ifndef _MRST_MAX3110_H
+#define _MRST_MAX3110_H
+
+#define MAX3110_HIGH_CLK        0x1     /* 3.6864 MHZ */
+#define MAX3110_LOW_CLK         0x0     /* 1.8432 MHZ */
+
+/* status bits for all 4 MAX3110 operate modes */
+#define MAX3110_READ_DATA_AVAILABLE     (1 << 15)
+#define MAX3110_WRITE_BUF_EMPTY         (1 << 14)
+
+#define WC_TAG                  (3 << 14)
+#define RC_TAG                  (1 << 14)
+#define WD_TAG                  (2 << 14)
+#define RD_TAG                  (0 << 14)
+
+/* bits def for write configuration */
+#define WC_FIFO_ENABLE_MASK     (1 << 13)
+#define WC_FIFO_ENABLE          (0 << 13)
+
+#define WC_SW_SHDI              (1 << 12)
+
+#define WC_IRQ_MASK             (0xF << 8)
+#define WC_TXE_IRQ_ENABLE       (1 << 11)       /* TX empty irq */
+#define WC_RXA_IRQ_ENABLE       (1 << 10)       /* RX availabe irq */
+#define WC_PAR_HIGH_IRQ_ENABLE  (1 << 9)
+#define WC_REC_ACT_IRQ_ENABLE   (1 << 8)
+
+#define WC_IRDA_ENABLE          (1 << 7)
+
+#define WC_STOPBITS_MASK        (1 << 6)
+#define WC_2_STOPBITS           (1 << 6)
+#define WC_1_STOPBITS           (0 << 6)
+
+#define WC_PARITY_ENABLE_MASK   (1 << 5)
+#define WC_PARITY_ENABLE        (1 << 5)
+
+#define WC_WORDLEN_MASK         (1 << 4)
+#define WC_7BIT_WORD            (1 << 4)
+#define WC_8BIT_WORD            (0 << 4)
+
+#define WC_BAUD_DIV_MASK        (0xF)
+#define WC_BAUD_DR1             (0x0)
+#define WC_BAUD_DR2             (0x1)
+#define WC_BAUD_DR4             (0x2)
+#define WC_BAUD_DR8             (0x3)
+#define WC_BAUD_DR16            (0x4)
+#define WC_BAUD_DR32            (0x5)
+#define WC_BAUD_DR64            (0x6)
+#define WC_BAUD_DR128           (0x7)
+#define WC_BAUD_DR3             (0x8)
+#define WC_BAUD_DR6             (0x9)
+#define WC_BAUD_DR12            (0xA)
+#define WC_BAUD_DR24            (0xB)
+#define WC_BAUD_DR48            (0xC)
+#define WC_BAUD_DR96            (0xD)
+#define WC_BAUD_DR192           (0xE)
+#define WC_BAUD_DR384           (0xF)
+
+#endif