hdq driver for OMAP2430/3430

The HDQ/1-Wire module of TI OMAP2430/3430 platforms implement the hardware
protocol of the master functions of the Benchmark HDQ and the Dallas
Semiconductor 1-Wire protocols.  These protocols use a single wire for
communication between the master (HDQ/1-Wire controller) and the slave
(HDQ/1-Wire external compliant device).

This patch provides the HDQ driver to suppport TI OMAP2430/3430 platforms.

Signed-off-by: Madhusudhan Chikkature<madhu.cr@ti.com>
Acked-by: Felipe Balbi <felipe.balbi@nokia.com>
Acked-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 733 insertions, 0 deletions

diff --git a/drivers/w1/masters/Kconfig b/drivers/w1/masters/Kconfig
index c4493091c65..a14d5b6e4c7 100644
--- a/drivers/w1/masters/Kconfig
+++ b/drivers/w1/masters/Kconfig
@@ -52,5 +52,12 @@ config W1_MASTER_GPIO
 	  This support is also available as a module.  If so, the module
 	  will be called w1-gpio.ko.
 
+config HDQ_MASTER_OMAP
+	tristate "OMAP HDQ driver"
+	depends on ARCH_OMAP2430 || ARCH_OMAP34XX
+	help
+	  Say Y here if you want support for the 1-wire or HDQ Interface
+	  on an OMAP processor.
+
 endmenu
 
diff --git a/drivers/w1/masters/Makefile b/drivers/w1/masters/Makefile
index 1420b5bbdda..bc4714a75f3 100644
--- a/drivers/w1/masters/Makefile
+++ b/drivers/w1/masters/Makefile
@@ -7,3 +7,4 @@ obj-$(CONFIG_W1_MASTER_DS2490)		+= ds2490.o
 obj-$(CONFIG_W1_MASTER_DS2482)		+= ds2482.o
 obj-$(CONFIG_W1_MASTER_DS1WM)		+= ds1wm.o
 obj-$(CONFIG_W1_MASTER_GPIO)		+= w1-gpio.o
+obj-$(CONFIG_HDQ_MASTER_OMAP)		+= omap_hdq.o
diff --git a/drivers/w1/masters/omap_hdq.c b/drivers/w1/masters/omap_hdq.c
new file mode 100644
index 00000000000..1295625c482
--- /dev/null
+++ b/drivers/w1/masters/omap_hdq.c
@@ -0,0 +1,725 @@
+/*
+ * drivers/w1/masters/omap_hdq.c
+ *
+ * Copyright (C) 2007 Texas Instruments, Inc.
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2. This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+
+#include <asm/irq.h>
+#include <mach/hardware.h>
+
+#include "../w1.h"
+#include "../w1_int.h"
+
+#define	MOD_NAME	"OMAP_HDQ:"
+
+#define OMAP_HDQ_REVISION			0x00
+#define OMAP_HDQ_TX_DATA			0x04
+#define OMAP_HDQ_RX_DATA			0x08
+#define OMAP_HDQ_CTRL_STATUS			0x0c
+#define OMAP_HDQ_CTRL_STATUS_INTERRUPTMASK	(1<<6)
+#define OMAP_HDQ_CTRL_STATUS_CLOCKENABLE	(1<<5)
+#define OMAP_HDQ_CTRL_STATUS_GO			(1<<4)
+#define OMAP_HDQ_CTRL_STATUS_INITIALIZATION	(1<<2)
+#define OMAP_HDQ_CTRL_STATUS_DIR		(1<<1)
+#define OMAP_HDQ_CTRL_STATUS_MODE		(1<<0)
+#define OMAP_HDQ_INT_STATUS			0x10
+#define OMAP_HDQ_INT_STATUS_TXCOMPLETE		(1<<2)
+#define OMAP_HDQ_INT_STATUS_RXCOMPLETE		(1<<1)
+#define OMAP_HDQ_INT_STATUS_TIMEOUT		(1<<0)
+#define OMAP_HDQ_SYSCONFIG			0x14
+#define OMAP_HDQ_SYSCONFIG_SOFTRESET		(1<<1)
+#define OMAP_HDQ_SYSCONFIG_AUTOIDLE		(1<<0)
+#define OMAP_HDQ_SYSSTATUS			0x18
+#define OMAP_HDQ_SYSSTATUS_RESETDONE		(1<<0)
+
+#define OMAP_HDQ_FLAG_CLEAR			0
+#define OMAP_HDQ_FLAG_SET			1
+#define OMAP_HDQ_TIMEOUT			(HZ/5)
+
+#define OMAP_HDQ_MAX_USER			4
+
+static DECLARE_WAIT_QUEUE_HEAD(hdq_wait_queue);
+static int w1_id;
+
+struct hdq_data {
+	struct device		*dev;
+	void __iomem		*hdq_base;
+	/* lock status update */
+	struct  mutex		hdq_mutex;
+	int			hdq_usecount;
+	struct	clk		*hdq_ick;
+	struct	clk		*hdq_fck;
+	u8			hdq_irqstatus;
+	/* device lock */
+	spinlock_t		hdq_spinlock;
+	/*
+	 * Used to control the call to omap_hdq_get and omap_hdq_put.
+	 * HDQ Protocol: Write the CMD|REG_address first, followed by
+	 * the data wrire or read.
+	 */
+	int			init_trans;
+};
+
+static int __init omap_hdq_probe(struct platform_device *pdev);
+static int omap_hdq_remove(struct platform_device *pdev);
+
+static struct platform_driver omap_hdq_driver = {
+	.probe =	omap_hdq_probe,
+	.remove =	omap_hdq_remove,
+	.driver =	{
+		.name =	"omap_hdq",
+	},
+};
+
+static u8 omap_w1_read_byte(void *_hdq);
+static void omap_w1_write_byte(void *_hdq, u8 byte);
+static u8 omap_w1_reset_bus(void *_hdq);
+static void omap_w1_search_bus(void *_hdq, u8 search_type,
+	w1_slave_found_callback slave_found);
+
+
+static struct w1_bus_master omap_w1_master = {
+	.read_byte	= omap_w1_read_byte,
+	.write_byte	= omap_w1_write_byte,
+	.reset_bus	= omap_w1_reset_bus,
+	.search		= omap_w1_search_bus,
+};
+
+/* HDQ register I/O routines */
+static inline u8 hdq_reg_in(struct hdq_data *hdq_data, u32 offset)
+{
+	return __raw_readb(hdq_data->hdq_base + offset);
+}
+
+static inline void hdq_reg_out(struct hdq_data *hdq_data, u32 offset, u8 val)
+{
+	__raw_writeb(val, hdq_data->hdq_base + offset);
+}
+
+static inline u8 hdq_reg_merge(struct hdq_data *hdq_data, u32 offset,
+			u8 val, u8 mask)
+{
+	u8 new_val = (__raw_readb(hdq_data->hdq_base + offset) & ~mask)
+			| (val & mask);
+	__raw_writeb(new_val, hdq_data->hdq_base + offset);
+
+	return new_val;
+}
+
+/*
+ * Wait for one or more bits in flag change.
+ * HDQ_FLAG_SET: wait until any bit in the flag is set.
+ * HDQ_FLAG_CLEAR: wait until all bits in the flag are cleared.
+ * return 0 on success and -ETIMEDOUT in the case of timeout.
+ */
+static int hdq_wait_for_flag(struct hdq_data *hdq_data, u32 offset,
+		u8 flag, u8 flag_set, u8 *status)
+{
+	int ret = 0;
+	unsigned long timeout = jiffies + OMAP_HDQ_TIMEOUT;
+
+	if (flag_set == OMAP_HDQ_FLAG_CLEAR) {
+		/* wait for the flag clear */
+		while (((*status = hdq_reg_in(hdq_data, offset)) & flag)
+			&& time_before(jiffies, timeout)) {
+			schedule_timeout_uninterruptible(1);
+		}
+		if (*status & flag)
+			ret = -ETIMEDOUT;
+	} else if (flag_set == OMAP_HDQ_FLAG_SET) {
+		/* wait for the flag set */
+		while (!((*status = hdq_reg_in(hdq_data, offset)) & flag)
+			&& time_before(jiffies, timeout)) {
+			schedule_timeout_uninterruptible(1);
+		}
+		if (!(*status & flag))
+			ret = -ETIMEDOUT;
+	} else
+		return -EINVAL;
+
+	return ret;
+}
+
+/* write out a byte and fill *status with HDQ_INT_STATUS */
+static int hdq_write_byte(struct hdq_data *hdq_data, u8 val, u8 *status)
+{
+	int ret;
+	u8 tmp_status;
+	unsigned long irqflags;
+
+	*status = 0;
+
+	spin_lock_irqsave(&hdq_data->hdq_spinlock, irqflags);
+	/* clear interrupt flags via a dummy read */
+	hdq_reg_in(hdq_data, OMAP_HDQ_INT_STATUS);
+	/* ISR loads it with new INT_STATUS */
+	hdq_data->hdq_irqstatus = 0;
+	spin_unlock_irqrestore(&hdq_data->hdq_spinlock, irqflags);
+
+	hdq_reg_out(hdq_data, OMAP_HDQ_TX_DATA, val);
+
+	/* set the GO bit */
+	hdq_reg_merge(hdq_data, OMAP_HDQ_CTRL_STATUS, OMAP_HDQ_CTRL_STATUS_GO,
+		OMAP_HDQ_CTRL_STATUS_DIR | OMAP_HDQ_CTRL_STATUS_GO);
+	/* wait for the TXCOMPLETE bit */
+	ret = wait_event_timeout(hdq_wait_queue,
+		hdq_data->hdq_irqstatus, OMAP_HDQ_TIMEOUT);
+	if (ret == 0) {
+		dev_dbg(hdq_data->dev, "TX wait elapsed\n");
+		goto out;
+	}
+
+	*status = hdq_data->hdq_irqstatus;
+	/* check irqstatus */
+	if (!(*status & OMAP_HDQ_INT_STATUS_TXCOMPLETE)) {
+		dev_dbg(hdq_data->dev, "timeout waiting for"
+			"TXCOMPLETE/RXCOMPLETE, %x", *status);
+		ret = -ETIMEDOUT;
+		goto out;
+	}
+
+	/* wait for the GO bit return to zero */
+	ret = hdq_wait_for_flag(hdq_data, OMAP_HDQ_CTRL_STATUS,
+			OMAP_HDQ_CTRL_STATUS_GO,
+			OMAP_HDQ_FLAG_CLEAR, &tmp_status);
+	if (ret) {
+		dev_dbg(hdq_data->dev, "timeout waiting GO bit"
+			"return to zero, %x", tmp_status);
+	}
+
+out:
+	return ret;
+}
+
+/* HDQ Interrupt service routine */
+static irqreturn_t hdq_isr(int irq, void *_hdq)
+{
+	struct hdq_data *hdq_data = _hdq;
+	unsigned long irqflags;
+
+	spin_lock_irqsave(&hdq_data->hdq_spinlock, irqflags);
+	hdq_data->hdq_irqstatus = hdq_reg_in(hdq_data, OMAP_HDQ_INT_STATUS);
+	spin_unlock_irqrestore(&hdq_data->hdq_spinlock, irqflags);
+	dev_dbg(hdq_data->dev, "hdq_isr: %x", hdq_data->hdq_irqstatus);
+
+	if (hdq_data->hdq_irqstatus &
+		(OMAP_HDQ_INT_STATUS_TXCOMPLETE | OMAP_HDQ_INT_STATUS_RXCOMPLETE
+		| OMAP_HDQ_INT_STATUS_TIMEOUT)) {
+		/* wake up sleeping process */
+		wake_up(&hdq_wait_queue);
+	}
+
+	return IRQ_HANDLED;
+}
+
+/* HDQ Mode: always return success */
+static u8 omap_w1_reset_bus(void *_hdq)
+{
+	return 0;
+}
+
+/* W1 search callback function */
+static void omap_w1_search_bus(void *_hdq, u8 search_type,
+	w1_slave_found_callback slave_found)
+{
+	u64 module_id, rn_le, cs, id;
+
+	if (w1_id)
+		module_id = w1_id;
+	else
+		module_id = 0x1;
+
+	rn_le = cpu_to_le64(module_id);
+	/*
+	 * HDQ might not obey truly the 1-wire spec.
+	 * So calculate CRC based on module parameter.
+	 */
+	cs = w1_calc_crc8((u8 *)&rn_le, 7);
+	id = (cs << 56) | module_id;
+
+	slave_found(_hdq, id);
+}
+
+static int _omap_hdq_reset(struct hdq_data *hdq_data)
+{
+	int ret;
+	u8 tmp_status;
+
+	hdq_reg_out(hdq_data, OMAP_HDQ_SYSCONFIG, OMAP_HDQ_SYSCONFIG_SOFTRESET);
+	/*
+	 * Select HDQ mode & enable clocks.
+	 * It is observed that INT flags can't be cleared via a read and GO/INIT
+	 * won't return to zero if interrupt is disabled. So we always enable
+	 * interrupt.
+	 */
+	hdq_reg_out(hdq_data, OMAP_HDQ_CTRL_STATUS,
+		OMAP_HDQ_CTRL_STATUS_CLOCKENABLE |
+		OMAP_HDQ_CTRL_STATUS_INTERRUPTMASK);
+
+	/* wait for reset to complete */
+	ret = hdq_wait_for_flag(hdq_data, OMAP_HDQ_SYSSTATUS,
+		OMAP_HDQ_SYSSTATUS_RESETDONE, OMAP_HDQ_FLAG_SET, &tmp_status);
+	if (ret)
+		dev_dbg(hdq_data->dev, "timeout waiting HDQ reset, %x",
+				tmp_status);
+	else {
+		hdq_reg_out(hdq_data, OMAP_HDQ_CTRL_STATUS,
+			OMAP_HDQ_CTRL_STATUS_CLOCKENABLE |
+			OMAP_HDQ_CTRL_STATUS_INTERRUPTMASK);
+		hdq_reg_out(hdq_data, OMAP_HDQ_SYSCONFIG,
+			OMAP_HDQ_SYSCONFIG_AUTOIDLE);
+	}
+
+	return ret;
+}
+
+/* Issue break pulse to the device */
+static int omap_hdq_break(struct hdq_data *hdq_data)
+{
+	int ret = 0;
+	u8 tmp_status;
+	unsigned long irqflags;
+
+	ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
+	if (ret < 0) {
+		dev_dbg(hdq_data->dev, "Could not acquire mutex\n");
+		ret = -EINTR;
+		goto rtn;
+	}
+
+	spin_lock_irqsave(&hdq_data->hdq_spinlock, irqflags);
+	/* clear interrupt flags via a dummy read */
+	hdq_reg_in(hdq_data, OMAP_HDQ_INT_STATUS);
+	/* ISR loads it with new INT_STATUS */
+	hdq_data->hdq_irqstatus = 0;
+	spin_unlock_irqrestore(&hdq_data->hdq_spinlock, irqflags);
+
+	/* set the INIT and GO bit */
+	hdq_reg_merge(hdq_data, OMAP_HDQ_CTRL_STATUS,
+		OMAP_HDQ_CTRL_STATUS_INITIALIZATION | OMAP_HDQ_CTRL_STATUS_GO,
+		OMAP_HDQ_CTRL_STATUS_DIR | OMAP_HDQ_CTRL_STATUS_INITIALIZATION |
+		OMAP_HDQ_CTRL_STATUS_GO);
+
+	/* wait for the TIMEOUT bit */
+	ret = wait_event_timeout(hdq_wait_queue,
+		hdq_data->hdq_irqstatus, OMAP_HDQ_TIMEOUT);
+	if (ret == 0) {
+		dev_dbg(hdq_data->dev, "break wait elapsed\n");
+		ret = -EINTR;
+		goto out;
+	}
+
+	tmp_status = hdq_data->hdq_irqstatus;
+	/* check irqstatus */
+	if (!(tmp_status & OMAP_HDQ_INT_STATUS_TIMEOUT)) {
+		dev_dbg(hdq_data->dev, "timeout waiting for TIMEOUT, %x",
+				tmp_status);
+		ret = -ETIMEDOUT;
+		goto out;
+	}
+	/*
+	 * wait for both INIT and GO bits rerurn to zero.
+	 * zero wait time expected for interrupt mode.
+	 */
+	ret = hdq_wait_for_flag(hdq_data, OMAP_HDQ_CTRL_STATUS,
+			OMAP_HDQ_CTRL_STATUS_INITIALIZATION |
+			OMAP_HDQ_CTRL_STATUS_GO, OMAP_HDQ_FLAG_CLEAR,
+			&tmp_status);
+	if (ret)
+		dev_dbg(hdq_data->dev, "timeout waiting INIT&GO bits"
+			"return to zero, %x", tmp_status);
+
+out:
+	mutex_unlock(&hdq_data->hdq_mutex);
+rtn:
+	return ret;
+}
+
+static int hdq_read_byte(struct hdq_data *hdq_data, u8 *val)
+{
+	int ret = 0;
+	u8 status;
+	unsigned long timeout = jiffies + OMAP_HDQ_TIMEOUT;
+
+	ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
+	if (ret < 0) {
+		ret = -EINTR;
+		goto rtn;
+	}
+
+	if (!hdq_data->hdq_usecount) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (!(hdq_data->hdq_irqstatus & OMAP_HDQ_INT_STATUS_RXCOMPLETE)) {
+		hdq_reg_merge(hdq_data, OMAP_HDQ_CTRL_STATUS,
+			OMAP_HDQ_CTRL_STATUS_DIR | OMAP_HDQ_CTRL_STATUS_GO,
+			OMAP_HDQ_CTRL_STATUS_DIR | OMAP_HDQ_CTRL_STATUS_GO);
+		/*
+		 * The RX comes immediately after TX. It
+		 * triggers another interrupt before we
+		 * sleep. So we have to wait for RXCOMPLETE bit.
+		 */
+		while (!(hdq_data->hdq_irqstatus
+			& OMAP_HDQ_INT_STATUS_RXCOMPLETE)
+			&& time_before(jiffies, timeout)) {
+			schedule_timeout_uninterruptible(1);
+		}
+		hdq_reg_merge(hdq_data, OMAP_HDQ_CTRL_STATUS, 0,
+			OMAP_HDQ_CTRL_STATUS_DIR);
+		status = hdq_data->hdq_irqstatus;
+		/* check irqstatus */
+		if (!(status & OMAP_HDQ_INT_STATUS_RXCOMPLETE)) {
+			dev_dbg(hdq_data->dev, "timeout waiting for"
+				"RXCOMPLETE, %x", status);
+			ret = -ETIMEDOUT;
+			goto out;
+		}
+	}
+	/* the data is ready. Read it in! */
+	*val = hdq_reg_in(hdq_data, OMAP_HDQ_RX_DATA);
+out:
+	mutex_unlock(&hdq_data->hdq_mutex);
+rtn:
+	return 0;
+
+}
+
+/* Enable clocks and set the controller to HDQ mode */
+static int omap_hdq_get(struct hdq_data *hdq_data)
+{
+	int ret = 0;
+
+	ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
+	if (ret < 0) {
+		ret = -EINTR;
+		goto rtn;
+	}
+
+	if (OMAP_HDQ_MAX_USER == hdq_data->hdq_usecount) {
+		dev_dbg(hdq_data->dev, "attempt to exceed the max use count");
+		ret = -EINVAL;
+		goto out;
+	} else {
+		hdq_data->hdq_usecount++;
+		try_module_get(THIS_MODULE);
+		if (1 == hdq_data->hdq_usecount) {
+			if (clk_enable(hdq_data->hdq_ick)) {
+				dev_dbg(hdq_data->dev, "Can not enable ick\n");
+				ret = -ENODEV;
+				goto clk_err;
+			}
+			if (clk_enable(hdq_data->hdq_fck)) {
+				dev_dbg(hdq_data->dev, "Can not enable fck\n");
+				clk_disable(hdq_data->hdq_ick);
+				ret = -ENODEV;
+				goto clk_err;
+			}
+
+			/* make sure HDQ is out of reset */
+			if (!(hdq_reg_in(hdq_data, OMAP_HDQ_SYSSTATUS) &
+				OMAP_HDQ_SYSSTATUS_RESETDONE)) {
+				ret = _omap_hdq_reset(hdq_data);
+				if (ret)
+					/* back up the count */
+					hdq_data->hdq_usecount--;
+			} else {
+				/* select HDQ mode & enable clocks */
+				hdq_reg_out(hdq_data, OMAP_HDQ_CTRL_STATUS,
+					OMAP_HDQ_CTRL_STATUS_CLOCKENABLE |
+					OMAP_HDQ_CTRL_STATUS_INTERRUPTMASK);
+				hdq_reg_out(hdq_data, OMAP_HDQ_SYSCONFIG,
+					OMAP_HDQ_SYSCONFIG_AUTOIDLE);
+				hdq_reg_in(hdq_data, OMAP_HDQ_INT_STATUS);
+			}
+		}
+	}
+
+clk_err:
+	clk_put(hdq_data->hdq_ick);
+	clk_put(hdq_data->hdq_fck);
+out:
+	mutex_unlock(&hdq_data->hdq_mutex);
+rtn:
+	return ret;
+}
+
+/* Disable clocks to the module */
+static int omap_hdq_put(struct hdq_data *hdq_data)
+{
+	int ret = 0;
+
+	ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
+	if (ret < 0)
+		return -EINTR;
+
+	if (0 == hdq_data->hdq_usecount) {
+		dev_dbg(hdq_data->dev, "attempt to decrement use count"
+			"when it is zero");
+		ret = -EINVAL;
+	} else {
+		hdq_data->hdq_usecount--;
+		module_put(THIS_MODULE);
+		if (0 == hdq_data->hdq_usecount) {
+			clk_disable(hdq_data->hdq_ick);
+			clk_disable(hdq_data->hdq_fck);
+		}
+	}
+	mutex_unlock(&hdq_data->hdq_mutex);
+
+	return ret;
+}
+
+/* Read a byte of data from the device */
+static u8 omap_w1_read_byte(void *_hdq)
+{
+	struct hdq_data *hdq_data = _hdq;
+	u8 val = 0;
+	int ret;
+
+	ret = hdq_read_byte(hdq_data, &val);
+	if (ret) {
+		ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
+		if (ret < 0) {
+			dev_dbg(hdq_data->dev, "Could not acquire mutex\n");
+			return -EINTR;
+		}
+		hdq_data->init_trans = 0;
+		mutex_unlock(&hdq_data->hdq_mutex);
+		omap_hdq_put(hdq_data);
+		return -1;
+	}
+
+	/* Write followed by a read, release the module */
+	if (hdq_data->init_trans) {
+		ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
+		if (ret < 0) {
+			dev_dbg(hdq_data->dev, "Could not acquire mutex\n");
+			return -EINTR;
+		}
+		hdq_data->init_trans = 0;
+		mutex_unlock(&hdq_data->hdq_mutex);
+		omap_hdq_put(hdq_data);
+	}
+
+	return val;
+}
+
+/* Write a byte of data to the device */
+static void omap_w1_write_byte(void *_hdq, u8 byte)
+{
+	struct hdq_data *hdq_data = _hdq;
+	int ret;
+	u8 status;
+
+	/* First write to initialize the transfer */
+	if (hdq_data->init_trans == 0)
+		omap_hdq_get(hdq_data);
+
+	ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
+	if (ret < 0) {
+		dev_dbg(hdq_data->dev, "Could not acquire mutex\n");
+		return;
+	}
+	hdq_data->init_trans++;
+	mutex_unlock(&hdq_data->hdq_mutex);
+
+	ret = hdq_write_byte(hdq_data, byte, &status);
+	if (ret == 0) {
+		dev_dbg(hdq_data->dev, "TX failure:Ctrl status %x\n", status);
+		return;
+	}
+
+	/* Second write, data transfered. Release the module */
+	if (hdq_data->init_trans > 1) {
+		omap_hdq_put(hdq_data);
+		ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
+		if (ret < 0) {
+			dev_dbg(hdq_data->dev, "Could not acquire mutex\n");
+			return;
+		}
+		hdq_data->init_trans = 0;
+		mutex_unlock(&hdq_data->hdq_mutex);
+	}
+
+	return;
+}
+
+static int __init omap_hdq_probe(struct platform_device *pdev)
+{
+	struct hdq_data *hdq_data;
+	struct resource *res;
+	int ret, irq;
+	u8 rev;
+
+	hdq_data = kmalloc(sizeof(*hdq_data), GFP_KERNEL);
+	if (!hdq_data) {
+		dev_dbg(&pdev->dev, "unable to allocate memory\n");
+		ret = -ENOMEM;
+		goto err_kmalloc;
+	}
+
+	hdq_data->dev = &pdev->dev;
+	platform_set_drvdata(pdev, hdq_data);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_dbg(&pdev->dev, "unable to get resource\n");
+		ret = -ENXIO;
+		goto err_resource;
+	}
+
+	hdq_data->hdq_base = ioremap(res->start, SZ_4K);
+	if (!hdq_data->hdq_base) {
+		dev_dbg(&pdev->dev, "ioremap failed\n");
+		ret = -EINVAL;
+		goto err_ioremap;
+	}
+
+	/* get interface & functional clock objects */
+	hdq_data->hdq_ick = clk_get(&pdev->dev, "hdq_ick");
+	hdq_data->hdq_fck = clk_get(&pdev->dev, "hdq_fck");
+
+	if (IS_ERR(hdq_data->hdq_ick) || IS_ERR(hdq_data->hdq_fck)) {
+		dev_dbg(&pdev->dev, "Can't get HDQ clock objects\n");
+		if (IS_ERR(hdq_data->hdq_ick)) {
+			ret = PTR_ERR(hdq_data->hdq_ick);
+			goto err_clk;
+		}
+		if (IS_ERR(hdq_data->hdq_fck)) {
+			ret = PTR_ERR(hdq_data->hdq_fck);
+			clk_put(hdq_data->hdq_ick);
+			goto err_clk;
+		}
+	}
+
+	hdq_data->hdq_usecount = 0;
+	mutex_init(&hdq_data->hdq_mutex);
+
+	if (clk_enable(hdq_data->hdq_ick)) {
+		dev_dbg(&pdev->dev, "Can not enable ick\n");
+		ret = -ENODEV;
+		goto err_intfclk;
+	}
+
+	if (clk_enable(hdq_data->hdq_fck)) {
+		dev_dbg(&pdev->dev, "Can not enable fck\n");
+		ret = -ENODEV;
+		goto err_fnclk;
+	}
+
+	rev = hdq_reg_in(hdq_data, OMAP_HDQ_REVISION);
+	dev_info(&pdev->dev, "OMAP HDQ Hardware Rev %c.%c. Driver in %s mode\n",
+		(rev >> 4) + '0', (rev & 0x0f) + '0', "Interrupt");
+
+	spin_lock_init(&hdq_data->hdq_spinlock);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq	< 0) {
+		ret = -ENXIO;
+		goto err_irq;
+	}
+
+	ret = request_irq(irq, hdq_isr, IRQF_DISABLED, "omap_hdq", hdq_data);
+	if (ret < 0) {
+		dev_dbg(&pdev->dev, "could not request irq\n");
+		goto err_irq;
+	}
+
+	omap_hdq_break(hdq_data);
+
+	/* don't clock the HDQ until it is needed */
+	clk_disable(hdq_data->hdq_ick);
+	clk_disable(hdq_data->hdq_fck);
+
+	omap_w1_master.data = hdq_data;
+
+	ret = w1_add_master_device(&omap_w1_master);
+	if (ret) {
+		dev_dbg(&pdev->dev, "Failure in registering w1 master\n");
+		goto err_w1;
+	}
+
+	return 0;
+
+err_w1:
+err_irq:
+	clk_disable(hdq_data->hdq_fck);
+
+err_fnclk:
+	clk_disable(hdq_data->hdq_ick);
+
+err_intfclk:
+	clk_put(hdq_data->hdq_ick);
+	clk_put(hdq_data->hdq_fck);
+
+err_clk:
+	iounmap(hdq_data->hdq_base);
+
+err_ioremap:
+err_resource:
+	platform_set_drvdata(pdev, NULL);
+	kfree(hdq_data);
+
+err_kmalloc:
+	return ret;
+
+}
+
+static int omap_hdq_remove(struct platform_device *pdev)
+{
+	struct hdq_data *hdq_data = platform_get_drvdata(pdev);
+
+	mutex_lock(&hdq_data->hdq_mutex);
+
+	if (hdq_data->hdq_usecount) {
+		dev_dbg(&pdev->dev, "removed when use count is not zero\n");
+		return -EBUSY;
+	}
+
+	mutex_unlock(&hdq_data->hdq_mutex);
+
+	/* remove module dependency */
+	clk_put(hdq_data->hdq_ick);
+	clk_put(hdq_data->hdq_fck);
+	free_irq(INT_24XX_HDQ_IRQ, hdq_data);
+	platform_set_drvdata(pdev, NULL);
+	iounmap(hdq_data->hdq_base);
+	kfree(hdq_data);
+
+	return 0;
+}
+
+static int __init
+omap_hdq_init(void)
+{
+	return platform_driver_register(&omap_hdq_driver);
+}
+module_init(omap_hdq_init);
+
+static void __exit
+omap_hdq_exit(void)
+{
+	platform_driver_unregister(&omap_hdq_driver);
+}
+module_exit(omap_hdq_exit);
+
+module_param(w1_id, int, S_IRUSR);
+MODULE_PARM_DESC(w1_id, "1-wire id for the slave detection");
+
+MODULE_AUTHOR("Texas Instruments");
+MODULE_DESCRIPTION("HDQ driver Library");
+MODULE_LICENSE("GPL");