tty: MAX3100

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Signed-off-by: Alan "I'm hiding" Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 927 insertions, 0 deletions

diff --git a/drivers/serial/max3100.c b/drivers/serial/max3100.c
new file mode 100644
index 00000000000..9fd33e5622b
--- /dev/null
+++ b/drivers/serial/max3100.c
@@ -0,0 +1,927 @@
+/*
+ *
+ *  Copyright (C) 2008 Christian Pellegrin <chripell@evolware.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ *
+ * Notes: the MAX3100 doesn't provide an interrupt on CTS so we have
+ * to use polling for flow control. TX empty IRQ is unusable, since
+ * writing conf clears FIFO buffer and we cannot have this interrupt
+ * always asking us for attention.
+ *
+ * Example platform data:
+
+ static struct plat_max3100 max3100_plat_data = {
+ .loopback = 0,
+ .crystal = 0,
+ .poll_time = 100,
+ };
+
+ static struct spi_board_info spi_board_info[] = {
+ {
+ .modalias      = "max3100",
+ .platform_data = &max3100_plat_data,
+ .irq           = IRQ_EINT12,
+ .max_speed_hz  = 5*1000*1000,
+ .chip_select   = 0,
+ },
+ };
+
+ * The initial minor number is 209 in the low-density serial port:
+ * mknod /dev/ttyMAX0 c 204 209
+ */
+
+#define MAX3100_MAJOR 204
+#define MAX3100_MINOR 209
+/* 4 MAX3100s should be enough for everyone */
+#define MAX_MAX3100 4
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/serial_core.h>
+#include <linux/serial.h>
+#include <linux/spi/spi.h>
+#include <linux/freezer.h>
+
+#include <linux/serial_max3100.h>
+
+#define MAX3100_C    (1<<14)
+#define MAX3100_D    (0<<14)
+#define MAX3100_W    (1<<15)
+#define MAX3100_RX   (0<<15)
+
+#define MAX3100_WC   (MAX3100_W  | MAX3100_C)
+#define MAX3100_RC   (MAX3100_RX | MAX3100_C)
+#define MAX3100_WD   (MAX3100_W  | MAX3100_D)
+#define MAX3100_RD   (MAX3100_RX | MAX3100_D)
+#define MAX3100_CMD  (3 << 14)
+
+#define MAX3100_T    (1<<14)
+#define MAX3100_R    (1<<15)
+
+#define MAX3100_FEN  (1<<13)
+#define MAX3100_SHDN (1<<12)
+#define MAX3100_TM   (1<<11)
+#define MAX3100_RM   (1<<10)
+#define MAX3100_PM   (1<<9)
+#define MAX3100_RAM  (1<<8)
+#define MAX3100_IR   (1<<7)
+#define MAX3100_ST   (1<<6)
+#define MAX3100_PE   (1<<5)
+#define MAX3100_L    (1<<4)
+#define MAX3100_BAUD (0xf)
+
+#define MAX3100_TE   (1<<10)
+#define MAX3100_RAFE (1<<10)
+#define MAX3100_RTS  (1<<9)
+#define MAX3100_CTS  (1<<9)
+#define MAX3100_PT   (1<<8)
+#define MAX3100_DATA (0xff)
+
+#define MAX3100_RT   (MAX3100_R | MAX3100_T)
+#define MAX3100_RTC  (MAX3100_RT | MAX3100_CTS | MAX3100_RAFE)
+
+/* the following simulate a status reg for ignore_status_mask */
+#define MAX3100_STATUS_PE 1
+#define MAX3100_STATUS_FE 2
+#define MAX3100_STATUS_OE 4
+
+struct max3100_port {
+        struct uart_port port;
+        struct spi_device *spi;
+
+        int cts;                /* last CTS received for flow ctrl */
+        int tx_empty;           /* last TX empty bit */
+
+        spinlock_t conf_lock;   /* shared data */
+        int conf_commit;        /* need to make changes */
+        int conf;               /* configuration for the MAX31000
+                                 * (bits 0-7, bits 8-11 are irqs) */
+        int rts_commit;         /* need to change rts */
+        int rts;                /* rts status */
+        int baud;               /* current baud rate */
+
+        int parity;             /* keeps track if we should send parity */
+#define MAX3100_PARITY_ON 1
+#define MAX3100_PARITY_ODD 2
+#define MAX3100_7BIT 4
+        int rx_enabled;         /* if we should rx chars */
+
+        int irq;                /* irq assigned to the max3100 */
+
+        int minor;              /* minor number */
+        int crystal;            /* 1 if 3.6864Mhz crystal 0 for 1.8432 */
+        int loopback;           /* 1 if we are in loopback mode */
+
+        /* for handling irqs: need workqueue since we do spi_sync */
+        struct workqueue_struct *workqueue;
+        struct work_struct work;
+        /* set to 1 to make the workhandler exit as soon as possible */
+        int  force_end_work;
+        /* need to know we are suspending to avoid deadlock on workqueue */
+        int suspending;
+
+        /* hook for suspending MAX3100 via dedicated pin */
+        void (*max3100_hw_suspend) (int suspend);
+
+        /* poll time (in ms) for ctrl lines */
+        int poll_time;
+        /* and its timer */
+        struct timer_list       timer;
+};
+
+static struct max3100_port *max3100s[MAX_MAX3100]; /* the chips */
+static DEFINE_MUTEX(max3100s_lock);                /* race on probe */
+
+static int max3100_do_parity(struct max3100_port *s, u16 c)
+{
+        int parity;
+
+        if (s->parity & MAX3100_PARITY_ODD)
+                parity = 1;
+        else
+                parity = 0;
+
+        if (s->parity & MAX3100_7BIT)
+                c &= 0x7f;
+        else
+                c &= 0xff;
+
+        parity = parity ^ (hweight8(c) & 1);
+        return parity;
+}
+
+static int max3100_check_parity(struct max3100_port *s, u16 c)
+{
+        return max3100_do_parity(s, c) == ((c >> 8) & 1);
+}
+
+static void max3100_calc_parity(struct max3100_port *s, u16 *c)
+{
+        if (s->parity & MAX3100_7BIT)
+                *c &= 0x7f;
+        else
+                *c &= 0xff;
+
+        if (s->parity & MAX3100_PARITY_ON)
+                *c |= max3100_do_parity(s, *c) << 8;
+}
+
+static void max3100_work(struct work_struct *w);
+
+static void max3100_dowork(struct max3100_port *s)
+{
+        if (!s->force_end_work && !work_pending(&s->work) &&
+            !freezing(current) && !s->suspending)
+                queue_work(s->workqueue, &s->work);
+}
+
+static void max3100_timeout(unsigned long data)
+{
+        struct max3100_port *s = (struct max3100_port *)data;
+
+        if (s->port.info) {
+                max3100_dowork(s);
+                mod_timer(&s->timer, jiffies + s->poll_time);
+        }
+}
+
+static int max3100_sr(struct max3100_port *s, u16 tx, u16 *rx)
+{
+        struct spi_message message;
+        u16 etx, erx;
+        int status;
+        struct spi_transfer tran = {
+                .tx_buf = &etx,
+                .rx_buf = &erx,
+                .len = 2,
+        };
+
+        etx = cpu_to_be16(tx);
+        spi_message_init(&message);
+        spi_message_add_tail(&tran, &message);
+        status = spi_sync(s->spi, &message);
+        if (status) {
+                dev_warn(&s->spi->dev, "error while calling spi_sync\n");
+                return -EIO;
+        }
+        *rx = be16_to_cpu(erx);
+        s->tx_empty = (*rx & MAX3100_T) > 0;
+        dev_dbg(&s->spi->dev, "%04x - %04x\n", tx, *rx);
+        return 0;
+}
+
+static int max3100_handlerx(struct max3100_port *s, u16 rx)
+{
+        unsigned int ch, flg, status = 0;
+        int ret = 0, cts;
+
+        if (rx & MAX3100_R && s->rx_enabled) {
+                dev_dbg(&s->spi->dev, "%s\n", __func__);
+                ch = rx & (s->parity & MAX3100_7BIT ? 0x7f : 0xff);
+                if (rx & MAX3100_RAFE) {
+                        s->port.icount.frame++;
+                        flg = TTY_FRAME;
+                        status |= MAX3100_STATUS_FE;
+                } else {
+                        if (s->parity & MAX3100_PARITY_ON) {
+                                if (max3100_check_parity(s, rx)) {
+                                        s->port.icount.rx++;
+                                        flg = TTY_NORMAL;
+                                } else {
+                                        s->port.icount.parity++;
+                                        flg = TTY_PARITY;
+                                        status |= MAX3100_STATUS_PE;
+                                }
+                        } else {
+                                s->port.icount.rx++;
+                                flg = TTY_NORMAL;
+                        }
+                }
+                uart_insert_char(&s->port, status, MAX3100_STATUS_OE, ch, flg);
+                ret = 1;
+        }
+
+        cts = (rx & MAX3100_CTS) > 0;
+        if (s->cts != cts) {
+                s->cts = cts;
+                uart_handle_cts_change(&s->port, cts ? TIOCM_CTS : 0);
+        }
+
+        return ret;
+}
+
+static void max3100_work(struct work_struct *w)
+{
+        struct max3100_port *s = container_of(w, struct max3100_port, work);
+        int rxchars;
+        u16 tx, rx;
+        int conf, cconf, rts, crts;
+        struct circ_buf *xmit = &s->port.info->xmit;
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+
+        rxchars = 0;
+        do {
+                spin_lock(&s->conf_lock);
+                conf = s->conf;
+                cconf = s->conf_commit;
+                s->conf_commit = 0;
+                rts = s->rts;
+                crts = s->rts_commit;
+                s->rts_commit = 0;
+                spin_unlock(&s->conf_lock);
+                if (cconf)
+                        max3100_sr(s, MAX3100_WC | conf, &rx);
+                if (crts) {
+                        max3100_sr(s, MAX3100_WD | MAX3100_TE |
+                                   (s->rts ? MAX3100_RTS : 0), &rx);
+                        rxchars += max3100_handlerx(s, rx);
+                }
+
+                max3100_sr(s, MAX3100_RD, &rx);
+                rxchars += max3100_handlerx(s, rx);
+
+                if (rx & MAX3100_T) {
+                        tx = 0xffff;
+                        if (s->port.x_char) {
+                                tx = s->port.x_char;
+                                s->port.icount.tx++;
+                                s->port.x_char = 0;
+                        } else if (!uart_circ_empty(xmit) &&
+                                   !uart_tx_stopped(&s->port)) {
+                                tx = xmit->buf[xmit->tail];
+                                xmit->tail = (xmit->tail + 1) &
+                                        (UART_XMIT_SIZE - 1);
+                                s->port.icount.tx++;
+                        }
+                        if (tx != 0xffff) {
+                                max3100_calc_parity(s, &tx);
+                                tx |= MAX3100_WD | (s->rts ? MAX3100_RTS : 0);
+                                max3100_sr(s, tx, &rx);
+                                rxchars += max3100_handlerx(s, rx);
+                        }
+                }
+
+                if (rxchars > 16 && s->port.info->port.tty != NULL) {
+                        tty_flip_buffer_push(s->port.info->port.tty);
+                        rxchars = 0;
+                }
+                if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+                        uart_write_wakeup(&s->port);
+
+        } while (!s->force_end_work &&
+                 !freezing(current) &&
+                 ((rx & MAX3100_R) ||
+                  (!uart_circ_empty(xmit) &&
+                   !uart_tx_stopped(&s->port))));
+
+        if (rxchars > 0 && s->port.info->port.tty != NULL)
+                tty_flip_buffer_push(s->port.info->port.tty);
+}
+
+static irqreturn_t max3100_irq(int irqno, void *dev_id)
+{
+        struct max3100_port *s = dev_id;
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+
+        max3100_dowork(s);
+        return IRQ_HANDLED;
+}
+
+static void max3100_enable_ms(struct uart_port *port)
+{
+        struct max3100_port *s = container_of(port,
+                                              struct max3100_port,
+                                              port);
+
+        if (s->poll_time > 0)
+                mod_timer(&s->timer, jiffies);
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+}
+
+static void max3100_start_tx(struct uart_port *port)
+{
+        struct max3100_port *s = container_of(port,
+                                              struct max3100_port,
+                                              port);
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+
+        max3100_dowork(s);
+}
+
+static void max3100_stop_rx(struct uart_port *port)
+{
+        struct max3100_port *s = container_of(port,
+                                              struct max3100_port,
+                                              port);
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+
+        s->rx_enabled = 0;
+        spin_lock(&s->conf_lock);
+        s->conf &= ~MAX3100_RM;
+        s->conf_commit = 1;
+        spin_unlock(&s->conf_lock);
+        max3100_dowork(s);
+}
+
+static unsigned int max3100_tx_empty(struct uart_port *port)
+{
+        struct max3100_port *s = container_of(port,
+                                              struct max3100_port,
+                                              port);
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+
+        /* may not be truly up-to-date */
+        max3100_dowork(s);
+        return s->tx_empty;
+}
+
+static unsigned int max3100_get_mctrl(struct uart_port *port)
+{
+        struct max3100_port *s = container_of(port,
+                                              struct max3100_port,
+                                              port);
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+
+        /* may not be truly up-to-date */
+        max3100_dowork(s);
+        /* always assert DCD and DSR since these lines are not wired */
+        return (s->cts ? TIOCM_CTS : 0) | TIOCM_DSR | TIOCM_CAR;
+}
+
+static void max3100_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+        struct max3100_port *s = container_of(port,
+                                              struct max3100_port,
+                                              port);
+        int rts;
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+
+        rts = (mctrl & TIOCM_RTS) > 0;
+
+        spin_lock(&s->conf_lock);
+        if (s->rts != rts) {
+                s->rts = rts;
+                s->rts_commit = 1;
+                max3100_dowork(s);
+        }
+        spin_unlock(&s->conf_lock);
+}
+
+static void
+max3100_set_termios(struct uart_port *port, struct ktermios *termios,
+                    struct ktermios *old)
+{
+        struct max3100_port *s = container_of(port,
+                                              struct max3100_port,
+                                              port);
+        int baud = 0;
+        unsigned cflag;
+        u32 param_new, param_mask, parity = 0;
+        struct tty_struct *tty = s->port.info->port.tty;
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+        if (!tty)
+                return;
+
+        cflag = termios->c_cflag;
+        param_new = 0;
+        param_mask = 0;
+
+        baud = tty_get_baud_rate(tty);
+        param_new = s->conf & MAX3100_BAUD;
+        switch (baud) {
+        case 300:
+                if (s->crystal)
+                        baud = s->baud;
+                else
+                        param_new = 15;
+                break;
+        case 600:
+                param_new = 14 + s->crystal;
+                break;
+        case 1200:
+                param_new = 13 + s->crystal;
+                break;
+        case 2400:
+                param_new = 12 + s->crystal;
+                break;
+        case 4800:
+                param_new = 11 + s->crystal;
+                break;
+        case 9600:
+                param_new = 10 + s->crystal;
+                break;
+        case 19200:
+                param_new = 9 + s->crystal;
+                break;
+        case 38400:
+                param_new = 8 + s->crystal;
+                break;
+        case 57600:
+                param_new = 1 + s->crystal;
+                break;
+        case 115200:
+                param_new = 0 + s->crystal;
+                break;
+        case 230400:
+                if (s->crystal)
+                        param_new = 0;
+                else
+                        baud = s->baud;
+                break;
+        default:
+                baud = s->baud;
+        }
+        tty_encode_baud_rate(tty, baud, baud);
+        s->baud = baud;
+        param_mask |= MAX3100_BAUD;
+
+        if ((cflag & CSIZE) == CS8) {
+                param_new &= ~MAX3100_L;
+                parity &= ~MAX3100_7BIT;
+        } else {
+                param_new |= MAX3100_L;
+                parity |= MAX3100_7BIT;
+                cflag = (cflag & ~CSIZE) | CS7;
+        }
+        param_mask |= MAX3100_L;
+
+        if (cflag & CSTOPB)
+                param_new |= MAX3100_ST;
+        else
+                param_new &= ~MAX3100_ST;
+        param_mask |= MAX3100_ST;
+
+        if (cflag & PARENB) {
+                param_new |= MAX3100_PE;
+                parity |= MAX3100_PARITY_ON;
+        } else {
+                param_new &= ~MAX3100_PE;
+                parity &= ~MAX3100_PARITY_ON;
+        }
+        param_mask |= MAX3100_PE;
+
+        if (cflag & PARODD)
+                parity |= MAX3100_PARITY_ODD;
+        else
+                parity &= ~MAX3100_PARITY_ODD;
+
+        /* mask termios capabilities we don't support */
+        cflag &= ~CMSPAR;
+        termios->c_cflag = cflag;
+
+        s->port.ignore_status_mask = 0;
+        if (termios->c_iflag & IGNPAR)
+                s->port.ignore_status_mask |=
+                        MAX3100_STATUS_PE | MAX3100_STATUS_FE |
+                        MAX3100_STATUS_OE;
+
+        /* we are sending char from a workqueue so enable */
+        s->port.info->port.tty->low_latency = 1;
+
+        if (s->poll_time > 0)
+                del_timer_sync(&s->timer);
+
+        uart_update_timeout(port, termios->c_cflag, baud);
+
+        spin_lock(&s->conf_lock);
+        s->conf = (s->conf & ~param_mask) | (param_new & param_mask);
+        s->conf_commit = 1;
+        s->parity = parity;
+        spin_unlock(&s->conf_lock);
+        max3100_dowork(s);
+
+        if (UART_ENABLE_MS(&s->port, termios->c_cflag))
+                max3100_enable_ms(&s->port);
+}
+
+static void max3100_shutdown(struct uart_port *port)
+{
+        struct max3100_port *s = container_of(port,
+                                              struct max3100_port,
+                                              port);
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+
+        if (s->suspending)
+                return;
+
+        s->force_end_work = 1;
+
+        if (s->poll_time > 0)
+                del_timer_sync(&s->timer);
+
+        if (s->workqueue) {
+                flush_workqueue(s->workqueue);
+                destroy_workqueue(s->workqueue);
+                s->workqueue = NULL;
+        }
+        if (s->irq)
+                free_irq(s->irq, s);
+
+        /* set shutdown mode to save power */
+        if (s->max3100_hw_suspend)
+                s->max3100_hw_suspend(1);
+        else  {
+                u16 tx, rx;
+
+                tx = MAX3100_WC | MAX3100_SHDN;
+                max3100_sr(s, tx, &rx);
+        }
+}
+
+static int max3100_startup(struct uart_port *port)
+{
+        struct max3100_port *s = container_of(port,
+                                              struct max3100_port,
+                                              port);
+        char b[12];
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+
+        s->conf = MAX3100_RM;
+        s->baud = s->crystal ? 230400 : 115200;
+        s->rx_enabled = 1;
+
+        if (s->suspending)
+                return 0;
+
+        s->force_end_work = 0;
+        s->parity = 0;
+        s->rts = 0;
+
+        sprintf(b, "max3100-%d", s->minor);
+        s->workqueue = create_freezeable_workqueue(b);
+        if (!s->workqueue) {
+                dev_warn(&s->spi->dev, "cannot create workqueue\n");
+                return -EBUSY;
+        }
+        INIT_WORK(&s->work, max3100_work);
+
+        if (request_irq(s->irq, max3100_irq,
+                        IRQF_TRIGGER_FALLING, "max3100", s) < 0) {
+                dev_warn(&s->spi->dev, "cannot allocate irq %d\n", s->irq);
+                s->irq = 0;
+                destroy_workqueue(s->workqueue);
+                s->workqueue = NULL;
+                return -EBUSY;
+        }
+
+        if (s->loopback) {
+                u16 tx, rx;
+                tx = 0x4001;
+                max3100_sr(s, tx, &rx);
+        }
+
+        if (s->max3100_hw_suspend)
+                s->max3100_hw_suspend(0);
+        s->conf_commit = 1;
+        max3100_dowork(s);
+        /* wait for clock to settle */
+        msleep(50);
+
+        max3100_enable_ms(&s->port);
+
+        return 0;
+}
+
+static const char *max3100_type(struct uart_port *port)
+{
+        struct max3100_port *s = container_of(port,
+                                              struct max3100_port,
+                                              port);
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+
+        return s->port.type == PORT_MAX3100 ? "MAX3100" : NULL;
+}
+
+static void max3100_release_port(struct uart_port *port)
+{
+        struct max3100_port *s = container_of(port,
+                                              struct max3100_port,
+                                              port);
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+}
+
+static void max3100_config_port(struct uart_port *port, int flags)
+{
+        struct max3100_port *s = container_of(port,
+                                              struct max3100_port,
+                                              port);
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+
+        if (flags & UART_CONFIG_TYPE)
+                s->port.type = PORT_MAX3100;
+}
+
+static int max3100_verify_port(struct uart_port *port,
+                               struct serial_struct *ser)
+{
+        struct max3100_port *s = container_of(port,
+                                              struct max3100_port,
+                                              port);
+        int ret = -EINVAL;
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+
+        if (ser->type == PORT_UNKNOWN || ser->type == PORT_MAX3100)
+                ret = 0;
+        return ret;
+}
+
+static void max3100_stop_tx(struct uart_port *port)
+{
+        struct max3100_port *s = container_of(port,
+                                              struct max3100_port,
+                                              port);
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+}
+
+static int max3100_request_port(struct uart_port *port)
+{
+        struct max3100_port *s = container_of(port,
+                                              struct max3100_port,
+                                              port);
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+        return 0;
+}
+
+static void max3100_break_ctl(struct uart_port *port, int break_state)
+{
+        struct max3100_port *s = container_of(port,
+                                              struct max3100_port,
+                                              port);
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+}
+
+static struct uart_ops max3100_ops = {
+        .tx_empty       = max3100_tx_empty,
+        .set_mctrl      = max3100_set_mctrl,
+        .get_mctrl      = max3100_get_mctrl,
+        .stop_tx        = max3100_stop_tx,
+        .start_tx       = max3100_start_tx,
+        .stop_rx        = max3100_stop_rx,
+        .enable_ms      = max3100_enable_ms,
+        .break_ctl      = max3100_break_ctl,
+        .startup        = max3100_startup,
+        .shutdown       = max3100_shutdown,
+        .set_termios    = max3100_set_termios,
+        .type           = max3100_type,
+        .release_port   = max3100_release_port,
+        .request_port   = max3100_request_port,
+        .config_port    = max3100_config_port,
+        .verify_port    = max3100_verify_port,
+};
+
+static struct uart_driver max3100_uart_driver = {
+        .owner          = THIS_MODULE,
+        .driver_name    = "ttyMAX",
+        .dev_name       = "ttyMAX",
+        .major          = MAX3100_MAJOR,
+        .minor          = MAX3100_MINOR,
+        .nr             = MAX_MAX3100,
+};
+static int uart_driver_registered;
+
+static int __devinit max3100_probe(struct spi_device *spi)
+{
+        int i, retval;
+        struct plat_max3100 *pdata;
+        u16 tx, rx;
+
+        mutex_lock(&max3100s_lock);
+
+        if (!uart_driver_registered) {
+                uart_driver_registered = 1;
+                retval = uart_register_driver(&max3100_uart_driver);
+                if (retval) {
+                        printk(KERN_ERR "Couldn't register max3100 uart driver\n");
+                        mutex_unlock(&max3100s_lock);
+                        return retval;
+                }
+        }
+
+        for (i = 0; i < MAX_MAX3100; i++)
+                if (!max3100s[i])
+                        break;
+        if (i == MAX_MAX3100) {
+                dev_warn(&spi->dev, "too many MAX3100 chips\n");
+                mutex_unlock(&max3100s_lock);
+                return -ENOMEM;
+        }
+
+        max3100s[i] = kzalloc(sizeof(struct max3100_port), GFP_KERNEL);
+        if (!max3100s[i]) {
+                dev_warn(&spi->dev,
+                         "kmalloc for max3100 structure %d failed!\n", i);
+                mutex_unlock(&max3100s_lock);
+                return -ENOMEM;
+        }
+        max3100s[i]->spi = spi;
+        max3100s[i]->irq = spi->irq;
+        spin_lock_init(&max3100s[i]->conf_lock);
+        dev_set_drvdata(&spi->dev, max3100s[i]);
+        pdata = spi->dev.platform_data;
+        max3100s[i]->crystal = pdata->crystal;
+        max3100s[i]->loopback = pdata->loopback;
+        max3100s[i]->poll_time = pdata->poll_time * HZ / 1000;
+        if (pdata->poll_time > 0 && max3100s[i]->poll_time == 0)
+                max3100s[i]->poll_time = 1;
+        max3100s[i]->max3100_hw_suspend = pdata->max3100_hw_suspend;
+        max3100s[i]->minor = i;
+        init_timer(&max3100s[i]->timer);
+        max3100s[i]->timer.function = max3100_timeout;
+        max3100s[i]->timer.data = (unsigned long) max3100s[i];
+
+        dev_dbg(&spi->dev, "%s: adding port %d\n", __func__, i);
+        max3100s[i]->port.irq = max3100s[i]->irq;
+        max3100s[i]->port.uartclk = max3100s[i]->crystal ? 3686400 : 1843200;
+        max3100s[i]->port.fifosize = 16;
+        max3100s[i]->port.ops = &max3100_ops;
+        max3100s[i]->port.flags = UPF_SKIP_TEST | UPF_BOOT_AUTOCONF;
+        max3100s[i]->port.line = i;
+        max3100s[i]->port.type = PORT_MAX3100;
+        max3100s[i]->port.dev = &spi->dev;
+        retval = uart_add_one_port(&max3100_uart_driver, &max3100s[i]->port);
+        if (retval < 0)
+                dev_warn(&spi->dev,
+                         "uart_add_one_port failed for line %d with error %d\n",
+                         i, retval);
+
+        /* set shutdown mode to save power. Will be woken-up on open */
+        if (max3100s[i]->max3100_hw_suspend)
+                max3100s[i]->max3100_hw_suspend(1);
+        else {
+                tx = MAX3100_WC | MAX3100_SHDN;
+                max3100_sr(max3100s[i], tx, &rx);
+        }
+        mutex_unlock(&max3100s_lock);
+        return 0;
+}
+
+static int __devexit max3100_remove(struct spi_device *spi)
+{
+        struct max3100_port *s = dev_get_drvdata(&spi->dev);
+        int i;
+
+        mutex_lock(&max3100s_lock);
+
+        /* find out the index for the chip we are removing */
+        for (i = 0; i < MAX_MAX3100; i++)
+                if (max3100s[i] == s)
+                        break;
+
+        dev_dbg(&spi->dev, "%s: removing port %d\n", __func__, i);
+        uart_remove_one_port(&max3100_uart_driver, &max3100s[i]->port);
+        kfree(max3100s[i]);
+        max3100s[i] = NULL;
+
+        /* check if this is the last chip we have */
+        for (i = 0; i < MAX_MAX3100; i++)
+                if (max3100s[i]) {
+                        mutex_unlock(&max3100s_lock);
+                        return 0;
+                }
+        pr_debug("removing max3100 driver\n");
+        uart_unregister_driver(&max3100_uart_driver);
+
+        mutex_unlock(&max3100s_lock);
+        return 0;
+}
+
+#ifdef CONFIG_PM
+
+static int max3100_suspend(struct spi_device *spi, pm_message_t state)
+{
+        struct max3100_port *s = dev_get_drvdata(&spi->dev);
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+
+        disable_irq(s->irq);
+
+        s->suspending = 1;
+        uart_suspend_port(&max3100_uart_driver, &s->port);
+
+        if (s->max3100_hw_suspend)
+                s->max3100_hw_suspend(1);
+        else {
+                /* no HW suspend, so do SW one */
+                u16 tx, rx;
+
+                tx = MAX3100_WC | MAX3100_SHDN;
+                max3100_sr(s, tx, &rx);
+        }
+        return 0;
+}
+
+static int max3100_resume(struct spi_device *spi)
+{
+        struct max3100_port *s = dev_get_drvdata(&spi->dev);
+
+        dev_dbg(&s->spi->dev, "%s\n", __func__);
+
+        if (s->max3100_hw_suspend)
+                s->max3100_hw_suspend(0);
+        uart_resume_port(&max3100_uart_driver, &s->port);
+        s->suspending = 0;
+
+        enable_irq(s->irq);
+
+        s->conf_commit = 1;
+        if (s->workqueue)
+                max3100_dowork(s);
+
+        return 0;
+}
+
+#else
+#define max3100_suspend NULL
+#define max3100_resume  NULL
+#endif
+
+static struct spi_driver max3100_driver = {
+        .driver = {
+                .name           = "max3100",
+                .bus            = &spi_bus_type,
+                .owner          = THIS_MODULE,
+        },
+
+        .probe          = max3100_probe,
+        .remove         = __devexit_p(max3100_remove),
+        .suspend        = max3100_suspend,
+        .resume         = max3100_resume,
+};
+
+static int __init max3100_init(void)
+{
+        return spi_register_driver(&max3100_driver);
+}
+module_init(max3100_init);
+
+static void __exit max3100_exit(void)
+{
+        spi_unregister_driver(&max3100_driver);
+}
+module_exit(max3100_exit);
+
+MODULE_DESCRIPTION("MAX3100 driver");
+MODULE_AUTHOR("Christian Pellegrin <chripell@evolware.org>");
+MODULE_LICENSE("GPL");