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Gmane
From: Alan Cox <alan <at> lxorguk.ukuu.org.uk>
Subject: [PATCH] tty: MAX3100
Newsgroups: gmane.linux.kernel
Date: Wednesday 8th April 2009 19:13:16 UTC (over 7 years ago)
Thou shalt remember to use 'git add' or errors shall be visited on your
downloads and there shall be wrath from on list and much gnashing of teeth.

Thou shalt remember to use git status or there shall be catcalls and much
embarrasment shall come to pass.

Signed-off-by: Alan "I'm hiding" Cox 
---

 drivers/serial/max3100.c       |  927
++++++++++++++++++++++++++++++++++++++++
 include/linux/serial_max3100.h |   52 ++
 2 files changed, 979 insertions(+), 0 deletions(-)
 create mode 100644 drivers/serial/max3100.c
 create mode 100644 include/linux/serial_max3100.h


diff --git a/drivers/serial/max3100.c b/drivers/serial/max3100.c
new file mode 100644
index 0000000..9fd33e5
--- /dev/null
+++ b/drivers/serial/max3100.c
@@ -0,0 +1,927 @@
+/*
+ *
+ *  Copyright (C) 2008 Christian Pellegrin 
+ *
+ * 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 
+#include 
+#include 
+#include 
+#include 
+#include 
+
+#include 
+
+#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 ");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/serial_max3100.h
b/include/linux/serial_max3100.h
new file mode 100644
index 0000000..4976bef
--- /dev/null
+++ b/include/linux/serial_max3100.h
@@ -0,0 +1,52 @@
+/*
+ *
+ *  Copyright (C) 2007 Christian Pellegrin
+ *
+ * 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.
+ */
+
+
+#ifndef _LINUX_SERIAL_MAX3100_H
+#define _LINUX_SERIAL_MAX3100_H 1
+
+
+/**
+ * struct plat_max3100 - MAX3100 SPI UART platform data
+ * @loopback:            force MAX3100 in loopback
+ * @crystal:             1 for 3.6864 Mhz, 0 for 1.8432
+ * @max3100_hw_suspend:  MAX3100 has a shutdown pin. This is a hook
+ *                       called on suspend and resume to activate it.
+ * @poll_time:           poll time for CTS signal in ms, 0 disables (so no
hw
+ *                       flow ctrl is possible but you have less CPU
usage)
+ *
+ * You should use this structure in your machine description to specify
+ * how the MAX3100 is connected. Example:
+ *
+ * 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,
+ * },
+ * };
+ *
+ **/
+struct plat_max3100 {
+	int loopback;
+	int crystal;
+	void (*max3100_hw_suspend) (int suspend);
+	int poll_time;
+};
+
+#endif
 
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