serial: spi: add spi-uart driver for Maxim 3110

转载 于 2010-04-22 00:33:00 发布 · 1.7k 阅读 · 1
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#struct #parallel #2010 #timer #module #thread

 

http://lwn.net/Articles/301914/

 

MAX3100 SPI UART driver

From: Christian Pellegrin <chripell@gmail.com>
To: linux-kernel@vger.kernel.org
Subject: [PATCH RESEND] MAX3100 SPI UART driver
Date: Thu, 2 Oct 2008 10:39:13 +0200
Message-ID: <12229367533638-git-send-email-chripell@gmail.com>
Cc: linux-serial@vger.kernel.org, spi-devel-general@lists.sourceforge.net, alan@lxorguk.ukuu.org.uk, akpm@linux-foundation.org, Christian Pellegrin <chripell@fsfe.org>
Archive-link: Article, Thread

 

This patch adds support for the MAX3100 SPI UART. I am still
waiting for a minor number from device@lanana.org so that
may change.

Generated on  20081002  against v2.6.27-rc7

Signed-off-by: Christian Pellegrin <chripell@fsfe.org>
---
 drivers/serial/Kconfig         |    6 +-
 drivers/serial/Makefile        |    1 +
 drivers/serial/max3100.c       |  924 ++++++++++++++++++++++++++++++++++++++++
 include/linux/serial_core.h    |    3 +
 include/linux/serial_max3100.h |   53 +++
 5 files changed, 986 insertions(+), 1 deletions(-)

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 77cb342..de3193d 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -509,7 +509,11 @@ config SERIAL_S3C2440
 	help
 	  Serial port support for the Samsung S3C2440 and S3C2442 SoC
 
-
+config SERIAL_MAX3100
+        tristate "MAX3100 support"
+        depends on SPI
+        help
+          MAX3100 chip support
 
 config SERIAL_DZ
 	bool "DECstation DZ serial driver"
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 7e7383e..21c3daf 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -31,6 +31,7 @@ obj-$(CONFIG_SERIAL_S3C2400) += s3c2400.o
 obj-$(CONFIG_SERIAL_S3C2410) += s3c2410.o
 obj-$(CONFIG_SERIAL_S3C2412) += s3c2412.o
 obj-$(CONFIG_SERIAL_S3C2440) += s3c2440.o
+obj-$(CONFIG_SERIAL_MAX3100) += max3100.o
 obj-$(CONFIG_SERIAL_SUNCORE) += suncore.o
 obj-$(CONFIG_SERIAL_SUNHV) += sunhv.o
 obj-$(CONFIG_SERIAL_SUNZILOG) += sunzilog.o
diff --git a/drivers/serial/max3100.c b/drivers/serial/max3100.c
new file mode 100644
index 0000000..7a269a6
--- /dev/null
+++ b/drivers/serial/max3100.c
@@ -0,0 +1,924 @@
+/*
+ *
+ *  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 192 in the low-density serial port:
+ * mknod /dev/ttyMAX0 c 204 192
+ */
+
+#define MAX3100_MAJOR 204
+#define MAX3100_MINOR 192
+/* 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);
+	}
+	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);
+		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;
+	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");
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 3b2f6c0..32c9fa9 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -155,6 +155,9 @@
 
 #define PORT_SC26XX	82
 
+/* MAX3100 */
+#define PORT_MAX3100    83
+
 #ifdef __KERNEL__
 
 #include <linux/compiler.h>
diff --git a/include/linux/serial_max3100.h b/include/linux/serial_max3100.h
new file mode 100644
index 0000000..b7e9a01
--- /dev/null
+++ b/include/linux/serial_max3100.h
@@ -0,0 +1,53 @@
+
+/*
+ *
+ *  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
--
1.4.4.4
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https://patchwork.kernel.org/patch/81910/

 

serial: spi: add spi-uart driver for Maxim 3110

 

SubmitterFeng Tang
Date2010-02-25 06:39:40
Message ID<20100225143940.40e21ff7@feng-i7>
Downloadmbox | patch
Permalink/patch/81910/
State Not Applicable
Headersshow

Comments

Feng Tang - 2010-02-25 06:39:40 
On Thu, 25 Feb 2010 07:18:32 +0800
Andrew Morton <akpm@linux-foundation.org> wrote:

> > ...
> >
> > +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,
> > +				max->flags ||
> > kthread_should_stop());
> > +		set_bit(0, &max->mthread_up);
> > +
> > +		if (use_irq && test_bit(M3110_IRQ_PENDING,
> > &max->flags)) {
> > +			max3110_con_receive(max);
> > +			clear_bit(M3110_IRQ_PENDING, &max->flags);
> > +		}
> > +
> > +		/* First handle console output */
> > +		if (test_bit(M3110_CON_TX_NEED, &max->flags)) {
> > +			send_circ_buf(max, xmit);
> > +			clear_bit(M3110_CON_TX_NEED, &max->flags);
> > +		}
> > +
> > +		/* Handle uart output */
> > +		if (test_bit(M3110_UART_TX_NEED, &max->flags)) {
> > +			transmit_char(max);
> > +			clear_bit(M3110_UART_TX_NEED, &max->flags);
> > +		}
> > +		clear_bit(0, &max->mthread_up);
> > +	} while (!kthread_should_stop());
> > +
> > +	return ret;
> > +}
> > +
> > +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 */
> > +	set_bit(M3110_IRQ_PENDING, &max->flags);
> > +
> > +	if (!test_bit(0, &max->mthread_up))
> > +		wake_up_process(max->main_thread);
> > +
> > +	return IRQ_HANDLED;
> > +}
> 
> The manipulation of mthread_up here (and in several other places) is
> clearly quite racy.  If you hit that race, the thread will not wake up
> and the driver will sit there not doing anything until some other
> event happens.
> 
> This is perhaps fixable with test_and_set_bit() and
> test_and_clear_bit() (need to think about that) or, of course, by
> adding locking.
> 
> But a simpler fix is just to delete mthread_up altogether.
> wake_up_process() on a running process is an OK thing to do and
> hopefully isn't terribly slow.

Yes, wake_up_process won't harm a running process, our driver's case
is a little special, the console's write() func may call
wake_up_process() for every character in the buffer, thus we will
try to avoid to call it. mthread_up can't be removed as it is also
referenced in read_thread.

I prefer to use the test_and_set/clear_bit for "mthread_up".

Thanks,
Feng



------------------------------------------------------------------------------
Download Intel&#174; Parallel Studio Eval
Try the new software tools for yourself. Speed compiling, find bugs
proactively, and fine-tune applications for parallel performance.
See why Intel Parallel Studio got high marks during beta.
http://p.sf.net/sfu/intel-sw-dev

Patch

diff --git a/drivers/serial/max3110.c b/drivers/serial/max3110.c
index e8c44fa..d5bd71f 100644
--- a/drivers/serial/max3110.c
+++ b/drivers/serial/max3110.c
@@ -400,7 +400,7 @@  static int max3110_main_thread(void *_max)
 	do {
 		wait_event_interruptible(*wq,
 				max->flags || kthread_should_stop());
-		set_bit(0, &max->mthread_up);
+		test_and_set_bit(0, &max->mthread_up);
 
 		if (use_irq && test_bit(M3110_IRQ_PENDING, &max->flags)) {
 			max3110_con_receive(max);
@@ -418,7 +418,7 @@  static int max3110_main_thread(void *_max)
 			transmit_char(max);
 			clear_bit(M3110_UART_TX_NEED, &max->flags);
 		}
-		clear_bit(0, &max->mthread_up);
+		test_and_clear_bit(0, &max->mthread_up);
 	} while (!kthread_should_stop());
 
 	return ret;

 

https://patchwork.kernel.org/patch/83120/

 

Feng Tang - 2010-03-02 03:38:17 
On Fri, 26 Feb 2010 17:59:38 +0800
Masakazu Mokuno <mokuno@sm.sony.co.jp> wrote:

> Hi,
> 
> > +	u8 *pbuf, valid_str[M3110_RX_FIFO_DEPTH];
> > +	int i, j;
> > +
> > +	memset(obuf, 0, sizeof(obuf));
> > +	memset(obuf, 0, sizeof(ibuf));
> 
> memset(ibuf, 0, sizeof(ibuf))?

thanks for the catch, here is a follow on patch



------------------------------------------------------------------------------
Download Intel&#174; Parallel Studio Eval
Try the new software tools for yourself. Speed compiling, find bugs
proactively, and fine-tune applications for parallel performance.
See why Intel Parallel Studio got high marks during beta.
http://p.sf.net/sfu/intel-sw-dev

Patch

diff --git a/drivers/serial/max3110.c b/drivers/serial/max3110.c
index 3283ba6..3dd2082 100644
--- a/drivers/serial/max3110.c
+++ b/drivers/serial/max3110.c
@@ -142,7 +142,7 @@  static int max3110_read_multi(struct uart_max3110 *max, u8 *buf)
 	int i, j;
 
 	memset(obuf, 0, sizeof(obuf));
-	memset(obuf, 0, sizeof(ibuf));
+	memset(ibuf, 0, sizeof(ibuf));
 
 	if (max3110_write_then_read(max, obuf, ibuf,
 				M3110_RX_FIFO_DEPTH * 2, 1))
devehe
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