diff mbox

[RFC,1/5] i2c: introduce i2c-cbus driver

Message ID 1346189667-32330-2-git-send-email-aaro.koskinen@iki.fi (mailing list archive)
State New, archived
Headers show

Commit Message

Aaro Koskinen Aug. 28, 2012, 9:34 p.m. UTC 
Add i2c driver to enable access to devices behind CBUS on Nokia Internet
Tablets.

Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: linux-i2c@vger.kernel.org
---
 drivers/i2c/busses/Kconfig    |   10 ++
 drivers/i2c/busses/Makefile   |    1 +
 drivers/i2c/busses/i2c-cbus.c |  342 +++++++++++++++++++++++++++++++++++++++++
 include/linux/i2c-cbus.h      |   27 ++++
 4 files changed, 380 insertions(+), 0 deletions(-)
 create mode 100644 drivers/i2c/busses/i2c-cbus.c
 create mode 100644 include/linux/i2c-cbus.h

Comments

Tony Lindgren Aug. 29, 2012, 11:35 p.m. UTC | #1 
* Aaro Koskinen <aaro.koskinen@iki.fi> [120828 14:35]:
> Add i2c driver to enable access to devices behind CBUS on Nokia Internet
> Tablets.

Can you please do also a separate patch for the device tree binding for
getting the GPIO pins for this controller? 

Other than that thanks for doing this and:

Acked-by: Tony Lindgren <tony@atomide.com>
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Felipe Balbi Aug. 30, 2012, 3:34 p.m. UTC | #2 
On Wed, Aug 29, 2012 at 12:34:23AM +0300, Aaro Koskinen wrote:
> Add i2c driver to enable access to devices behind CBUS on Nokia Internet
> Tablets.
> 
> Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
> Cc: linux-i2c@vger.kernel.org

Acked-by: Felipe Balbi <balbi@ti.com>

> ---
>  drivers/i2c/busses/Kconfig    |   10 ++
>  drivers/i2c/busses/Makefile   |    1 +
>  drivers/i2c/busses/i2c-cbus.c |  342 +++++++++++++++++++++++++++++++++++++++++
>  include/linux/i2c-cbus.h      |   27 ++++
>  4 files changed, 380 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/i2c/busses/i2c-cbus.c
>  create mode 100644 include/linux/i2c-cbus.h
> 
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index b4aaa1b..184ef43 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -331,6 +331,16 @@ config I2C_BLACKFIN_TWI_CLK_KHZ
>  	help
>  	  The unit of the TWI clock is kHz.
>  
> +config I2C_CBUS
> +	tristate "CBUS I2C driver"
> +	depends on GENERIC_GPIO
> +	help
> +	  Support for CBUS access using I2C API. Mostly relevant for Nokia
> +	  Internet Tablets (770, N800 and N810).
> +
> +	  This driver can also be built as a module.  If so, the module
> +	  will be called i2c-cbus.
> +
>  config I2C_CPM
>  	tristate "Freescale CPM1 or CPM2 (MPC8xx/826x)"
>  	depends on (CPM1 || CPM2) && OF_I2C
> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> index ce3c2be..44dbfd1 100644
> --- a/drivers/i2c/busses/Makefile
> +++ b/drivers/i2c/busses/Makefile
> @@ -31,6 +31,7 @@ obj-$(CONFIG_I2C_POWERMAC)	+= i2c-powermac.o
>  obj-$(CONFIG_I2C_AT91)		+= i2c-at91.o
>  obj-$(CONFIG_I2C_AU1550)	+= i2c-au1550.o
>  obj-$(CONFIG_I2C_BLACKFIN_TWI)	+= i2c-bfin-twi.o
> +obj-$(CONFIG_I2C_CBUS)		+= i2c-cbus.o
>  obj-$(CONFIG_I2C_CPM)		+= i2c-cpm.o
>  obj-$(CONFIG_I2C_DAVINCI)	+= i2c-davinci.o
>  obj-$(CONFIG_I2C_DESIGNWARE_PLATFORM)	+= i2c-designware-platform.o
> diff --git a/drivers/i2c/busses/i2c-cbus.c b/drivers/i2c/busses/i2c-cbus.c
> new file mode 100644
> index 0000000..3cc5be4
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-cbus.c
> @@ -0,0 +1,342 @@
> +/*
> + * CBUS I2C driver for Nokia Internet Tablets.
> + *
> + * Copyright (C) 2004-2010 Nokia Corporation
> + *
> + * Based on code written by Juha Yrjölä, David Weinehall, Mikko Ylinen and
> + * Felipe Balbi. Converted to I2C driver by Aaro Koskinen.
> + *
> + * This file is subject to the terms and conditions of the GNU General
> + * Public License. See the file "COPYING" in the main directory of this
> + * archive for more details.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/gpio.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/delay.h>
> +#include <linux/slab.h>
> +#include <linux/init.h>
> +#include <linux/errno.h>
> +#include <linux/platform_device.h>
> +#include <linux/i2c.h>
> +#include <linux/i2c-cbus.h>
> +#include <linux/io.h>
> +
> +struct cbus_host {
> +	/* host lock */
> +	spinlock_t	lock;
> +
> +	struct device	*dev;
> +
> +	int		clk_gpio;
> +	int		dat_gpio;
> +	int		sel_gpio;
> +};
> +
> +/**
> + * cbus_send_bit - sends one bit over the bus
> + * @host: the host we're using
> + * @bit: one bit of information to send
> + * @input: whether to set data pin as input after sending
> + */
> +static int cbus_send_bit(struct cbus_host *host, unsigned bit,
> +		unsigned input)
> +{
> +	int ret = 0;
> +
> +	gpio_set_value(host->dat_gpio, bit ? 1 : 0);
> +	gpio_set_value(host->clk_gpio, 1);
> +
> +	/* The data bit is read on the rising edge of CLK */
> +	if (input)
> +		ret = gpio_direction_input(host->dat_gpio);
> +
> +	gpio_set_value(host->clk_gpio, 0);
> +
> +	return ret;
> +}
> +
> +/**
> + * cbus_send_data - sends @len amount of data over the bus
> + * @host: the host we're using
> + * @data: the data to send
> + * @len: size of the transfer
> + * @input: whether to set data pin as input after sending
> + */
> +static int cbus_send_data(struct cbus_host *host, unsigned data, unsigned len,
> +		unsigned input)
> +{
> +	int ret = 0;
> +	int i;
> +
> +	for (i = len; i > 0; i--) {
> +		ret = cbus_send_bit(host, data & (1 << (i - 1)),
> +				input && (i == 1));
> +		if (ret < 0)
> +			goto out;
> +	}
> +
> +out:
> +	return ret;
> +}
> +
> +/**
> + * cbus_receive_bit - receives one bit from the bus
> + * @host: the host we're using
> + */
> +static int cbus_receive_bit(struct cbus_host *host)
> +{
> +	int ret;
> +
> +	gpio_set_value(host->clk_gpio, 1);
> +	ret = gpio_get_value(host->dat_gpio);
> +	if (ret < 0)
> +		goto out;
> +	gpio_set_value(host->clk_gpio, 0);
> +
> +out:
> +	return ret;
> +}
> +
> +/**
> + * cbus_receive_word - receives 16-bit word from the bus
> + * @host: the host we're using
> + */
> +static int cbus_receive_word(struct cbus_host *host)
> +{
> +	int ret = 0;
> +	int i;
> +
> +	for (i = 16; i > 0; i--) {
> +		int bit = cbus_receive_bit(host);
> +
> +		if (bit < 0)
> +			goto out;
> +
> +		if (bit)
> +			ret |= 1 << (i - 1);
> +	}
> +
> +out:
> +	return ret;
> +}
> +
> +/**
> + * cbus_transfer - transfers data over the bus
> + * @host: the host we're using
> + * @rw: read/write flag
> + * @dev: device address
> + * @reg: register address
> + * @data: if @rw == I2C_SBUS_WRITE data to send otherwise 0
> + */
> +static int cbus_transfer(struct cbus_host *host, char rw, unsigned dev,
> +			 unsigned reg, unsigned data)
> +{
> +	unsigned long flags;
> +	int ret;
> +
> +	/* We don't want interrupts disturbing our transfer */
> +	spin_lock_irqsave(&host->lock, flags);
> +
> +	/* Reset state and start of transfer, SEL stays down during transfer */
> +	gpio_set_value(host->sel_gpio, 0);
> +
> +	/* Set the DAT pin to output */
> +	gpio_direction_output(host->dat_gpio, 1);
> +
> +	/* Send the device address */
> +	ret = cbus_send_data(host, dev, 3, 0);
> +	if (ret < 0) {
> +		dev_dbg(host->dev, "failed sending device addr\n");
> +		goto out;
> +	}
> +
> +	/* Send the rw flag */
> +	ret = cbus_send_bit(host, rw == I2C_SMBUS_READ, 0);
> +	if (ret < 0) {
> +		dev_dbg(host->dev, "failed sending read/write flag\n");
> +		goto out;
> +	}
> +
> +	/* Send the device address */
> +	ret = cbus_send_data(host, reg, 5, rw == I2C_SMBUS_READ);
> +	if (ret < 0) {
> +		dev_dbg(host->dev, "failed sending register addr\n");
> +		goto out;
> +	}
> +
> +	if (rw == I2C_SMBUS_WRITE) {
> +		ret = cbus_send_data(host, data, 16, 0);
> +		if (ret < 0) {
> +			dev_dbg(host->dev, "failed sending data\n");
> +			goto out;
> +		}
> +	} else {
> +		gpio_set_value(host->clk_gpio, 1);
> +
> +		ret = cbus_receive_word(host);
> +		if (ret < 0) {
> +			dev_dbg(host->dev, "failed receiving data\n");
> +			goto out;
> +		}
> +	}
> +
> +	/* Indicate end of transfer, SEL goes up until next transfer */
> +	gpio_set_value(host->sel_gpio, 1);
> +	gpio_set_value(host->clk_gpio, 1);
> +	gpio_set_value(host->clk_gpio, 0);
> +
> +out:
> +	spin_unlock_irqrestore(&host->lock, flags);
> +
> +	return ret;
> +}
> +
> +static int cbus_i2c_smbus_xfer(struct i2c_adapter	*adapter,
> +			       u16			addr,
> +			       unsigned short		flags,
> +			       char			read_write,
> +			       u8			command,
> +			       int			size,
> +			       union i2c_smbus_data	*data)
> +{
> +	struct cbus_host *chost = i2c_get_adapdata(adapter);
> +	int ret;
> +
> +	if (size != I2C_SMBUS_WORD_DATA)
> +		return -EINVAL;
> +
> +	ret = cbus_transfer(chost, read_write == I2C_SMBUS_READ, addr,
> +			    command, data->word);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (read_write == I2C_SMBUS_READ)
> +		data->word = ret;
> +
> +	return 0;
> +}
> +
> +static u32 cbus_i2c_func(struct i2c_adapter *adapter)
> +{
> +	return I2C_FUNC_SMBUS_READ_WORD_DATA | I2C_FUNC_SMBUS_WRITE_WORD_DATA;
> +}
> +
> +static const struct i2c_algorithm cbus_i2c_algo = {
> +	.smbus_xfer	= cbus_i2c_smbus_xfer,
> +	.functionality	= cbus_i2c_func,
> +};
> +
> +static int cbus_i2c_remove(struct platform_device *pdev)
> +{
> +	struct i2c_adapter *adapter = platform_get_drvdata(pdev);
> +	struct cbus_host *chost = i2c_get_adapdata(adapter);
> +	int ret;
> +
> +	ret = i2c_del_adapter(adapter);
> +	if (ret)
> +		return ret;
> +	gpio_free(chost->clk_gpio);
> +	gpio_free(chost->dat_gpio);
> +	gpio_free(chost->sel_gpio);
> +	kfree(chost);
> +	kfree(adapter);
> +	platform_set_drvdata(pdev, NULL);
> +
> +	return 0;
> +}
> +
> +static int cbus_i2c_probe(struct platform_device *pdev)
> +{
> +	struct i2c_cbus_platform_data *pdata = pdev->dev.platform_data;
> +	struct i2c_adapter *adapter;
> +	struct cbus_host *chost;
> +	struct gpio gpios[3];
> +	int ret;
> +
> +	adapter = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL);
> +	if (!adapter) {
> +		ret = -ENOMEM;
> +		goto error;
> +	}
> +
> +	chost = kzalloc(sizeof(*chost), GFP_KERNEL);
> +	if (!chost) {
> +		ret = -ENOMEM;
> +		goto error_mem;
> +	}
> +
> +	adapter->owner		= THIS_MODULE;
> +	adapter->class		= I2C_CLASS_HWMON;
> +	adapter->dev.parent	= &pdev->dev;
> +	adapter->nr		= pdev->id;
> +	adapter->timeout	= HZ;
> +	adapter->algo		= &cbus_i2c_algo;
> +	strlcpy(adapter->name, "CBUS I2C adapter", sizeof(adapter->name));
> +
> +	spin_lock_init(&chost->lock);
> +	chost->dev = &pdev->dev;
> +
> +	gpios[0].gpio  = chost->clk_gpio = pdata->clk_gpio;
> +	gpios[0].flags = GPIOF_OUT_INIT_LOW;
> +	gpios[0].label = "CBUS clk";
> +
> +	gpios[1].gpio  = chost->dat_gpio = pdata->dat_gpio;
> +	gpios[1].flags = GPIOF_IN;
> +	gpios[1].label = "CBUS data";
> +
> +	gpios[2].gpio  = chost->sel_gpio = pdata->sel_gpio;
> +	gpios[2].flags = GPIOF_OUT_INIT_HIGH;
> +	gpios[2].label = "CBUS sel";
> +
> +	ret = gpio_request_array(gpios, ARRAY_SIZE(gpios));
> +	if (ret)
> +		goto error_gpio;
> +
> +	gpio_set_value(chost->clk_gpio, 1);
> +	gpio_set_value(chost->clk_gpio, 0);
> +
> +	i2c_set_adapdata(adapter, chost);
> +	platform_set_drvdata(pdev, adapter);
> +
> +	ret = i2c_add_numbered_adapter(adapter);
> +	if (ret)
> +		goto error_i2c;
> +
> +	return 0;
> +
> +error_i2c:
> +	gpio_free_array(gpios, ARRAY_SIZE(gpios));
> +error_gpio:
> +	kfree(chost);
> +error_mem:
> +	kfree(adapter);
> +error:
> +	return ret;
> +}
> +
> +static struct platform_driver cbus_i2c_driver = {
> +	.probe	= cbus_i2c_probe,
> +	.remove	= cbus_i2c_remove,
> +	.driver	= {
> +		.owner	= THIS_MODULE,
> +		.name	= "i2c-cbus",
> +	},
> +};
> +module_platform_driver(cbus_i2c_driver);
> +
> +MODULE_ALIAS("platform:i2c-cbus");
> +MODULE_DESCRIPTION("CBUS I2C driver");
> +MODULE_AUTHOR("Juha Yrjölä");
> +MODULE_AUTHOR("David Weinehall");
> +MODULE_AUTHOR("Mikko Ylinen");
> +MODULE_AUTHOR("Felipe Balbi <felipe.balbi@nokia.com>");
> +MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@iki.fi>");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/i2c-cbus.h b/include/linux/i2c-cbus.h
> new file mode 100644
> index 0000000..636d726
> --- /dev/null
> +++ b/include/linux/i2c-cbus.h
> @@ -0,0 +1,27 @@
> +/*
> + * i2c-cbus.h - CBUS I2C platform_data definition
> + *
> + * Copyright (C) 2004-2009 Nokia Corporation
> + *
> + * Written by Felipe Balbi and Aaro Koskinen.
> + *
> + * This file is subject to the terms and conditions of the GNU General
> + * Public License. See the file "COPYING" in the main directory of this
> + * archive for more details.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#ifndef __INCLUDE_LINUX_I2C_CBUS_H
> +#define __INCLUDE_LINUX_I2C_CBUS_H
> +
> +struct i2c_cbus_platform_data {
> +	int dat_gpio;
> +	int clk_gpio;
> +	int sel_gpio;
> +};
> +
> +#endif /* __INCLUDE_LINUX_I2C_CBUS_H */
> -- 
> 1.7.2.5
> 
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diff mbox

Patch

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index b4aaa1b..184ef43 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -331,6 +331,16 @@  config I2C_BLACKFIN_TWI_CLK_KHZ
 	help
 	  The unit of the TWI clock is kHz.
 
+config I2C_CBUS
+	tristate "CBUS I2C driver"
+	depends on GENERIC_GPIO
+	help
+	  Support for CBUS access using I2C API. Mostly relevant for Nokia
+	  Internet Tablets (770, N800 and N810).
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-cbus.
+
 config I2C_CPM
 	tristate "Freescale CPM1 or CPM2 (MPC8xx/826x)"
 	depends on (CPM1 || CPM2) && OF_I2C
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index ce3c2be..44dbfd1 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -31,6 +31,7 @@  obj-$(CONFIG_I2C_POWERMAC)	+= i2c-powermac.o
 obj-$(CONFIG_I2C_AT91)		+= i2c-at91.o
 obj-$(CONFIG_I2C_AU1550)	+= i2c-au1550.o
 obj-$(CONFIG_I2C_BLACKFIN_TWI)	+= i2c-bfin-twi.o
+obj-$(CONFIG_I2C_CBUS)		+= i2c-cbus.o
 obj-$(CONFIG_I2C_CPM)		+= i2c-cpm.o
 obj-$(CONFIG_I2C_DAVINCI)	+= i2c-davinci.o
 obj-$(CONFIG_I2C_DESIGNWARE_PLATFORM)	+= i2c-designware-platform.o
diff --git a/drivers/i2c/busses/i2c-cbus.c b/drivers/i2c/busses/i2c-cbus.c
new file mode 100644
index 0000000..3cc5be4
--- /dev/null
+++ b/drivers/i2c/busses/i2c-cbus.c
@@ -0,0 +1,342 @@ 
+/*
+ * CBUS I2C driver for Nokia Internet Tablets.
+ *
+ * Copyright (C) 2004-2010 Nokia Corporation
+ *
+ * Based on code written by Juha Yrjölä, David Weinehall, Mikko Ylinen and
+ * Felipe Balbi. Converted to I2C driver by Aaro Koskinen.
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file "COPYING" in the main directory of this
+ * archive for more details.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/gpio.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/platform_device.h>
+#include <linux/i2c.h>
+#include <linux/i2c-cbus.h>
+#include <linux/io.h>
+
+struct cbus_host {
+	/* host lock */
+	spinlock_t	lock;
+
+	struct device	*dev;
+
+	int		clk_gpio;
+	int		dat_gpio;
+	int		sel_gpio;
+};
+
+/**
+ * cbus_send_bit - sends one bit over the bus
+ * @host: the host we're using
+ * @bit: one bit of information to send
+ * @input: whether to set data pin as input after sending
+ */
+static int cbus_send_bit(struct cbus_host *host, unsigned bit,
+		unsigned input)
+{
+	int ret = 0;
+
+	gpio_set_value(host->dat_gpio, bit ? 1 : 0);
+	gpio_set_value(host->clk_gpio, 1);
+
+	/* The data bit is read on the rising edge of CLK */
+	if (input)
+		ret = gpio_direction_input(host->dat_gpio);
+
+	gpio_set_value(host->clk_gpio, 0);
+
+	return ret;
+}
+
+/**
+ * cbus_send_data - sends @len amount of data over the bus
+ * @host: the host we're using
+ * @data: the data to send
+ * @len: size of the transfer
+ * @input: whether to set data pin as input after sending
+ */
+static int cbus_send_data(struct cbus_host *host, unsigned data, unsigned len,
+		unsigned input)
+{
+	int ret = 0;
+	int i;
+
+	for (i = len; i > 0; i--) {
+		ret = cbus_send_bit(host, data & (1 << (i - 1)),
+				input && (i == 1));
+		if (ret < 0)
+			goto out;
+	}
+
+out:
+	return ret;
+}
+
+/**
+ * cbus_receive_bit - receives one bit from the bus
+ * @host: the host we're using
+ */
+static int cbus_receive_bit(struct cbus_host *host)
+{
+	int ret;
+
+	gpio_set_value(host->clk_gpio, 1);
+	ret = gpio_get_value(host->dat_gpio);
+	if (ret < 0)
+		goto out;
+	gpio_set_value(host->clk_gpio, 0);
+
+out:
+	return ret;
+}
+
+/**
+ * cbus_receive_word - receives 16-bit word from the bus
+ * @host: the host we're using
+ */
+static int cbus_receive_word(struct cbus_host *host)
+{
+	int ret = 0;
+	int i;
+
+	for (i = 16; i > 0; i--) {
+		int bit = cbus_receive_bit(host);
+
+		if (bit < 0)
+			goto out;
+
+		if (bit)
+			ret |= 1 << (i - 1);
+	}
+
+out:
+	return ret;
+}
+
+/**
+ * cbus_transfer - transfers data over the bus
+ * @host: the host we're using
+ * @rw: read/write flag
+ * @dev: device address
+ * @reg: register address
+ * @data: if @rw == I2C_SBUS_WRITE data to send otherwise 0
+ */
+static int cbus_transfer(struct cbus_host *host, char rw, unsigned dev,
+			 unsigned reg, unsigned data)
+{
+	unsigned long flags;
+	int ret;
+
+	/* We don't want interrupts disturbing our transfer */
+	spin_lock_irqsave(&host->lock, flags);
+
+	/* Reset state and start of transfer, SEL stays down during transfer */
+	gpio_set_value(host->sel_gpio, 0);
+
+	/* Set the DAT pin to output */
+	gpio_direction_output(host->dat_gpio, 1);
+
+	/* Send the device address */
+	ret = cbus_send_data(host, dev, 3, 0);
+	if (ret < 0) {
+		dev_dbg(host->dev, "failed sending device addr\n");
+		goto out;
+	}
+
+	/* Send the rw flag */
+	ret = cbus_send_bit(host, rw == I2C_SMBUS_READ, 0);
+	if (ret < 0) {
+		dev_dbg(host->dev, "failed sending read/write flag\n");
+		goto out;
+	}
+
+	/* Send the device address */
+	ret = cbus_send_data(host, reg, 5, rw == I2C_SMBUS_READ);
+	if (ret < 0) {
+		dev_dbg(host->dev, "failed sending register addr\n");
+		goto out;
+	}
+
+	if (rw == I2C_SMBUS_WRITE) {
+		ret = cbus_send_data(host, data, 16, 0);
+		if (ret < 0) {
+			dev_dbg(host->dev, "failed sending data\n");
+			goto out;
+		}
+	} else {
+		gpio_set_value(host->clk_gpio, 1);
+
+		ret = cbus_receive_word(host);
+		if (ret < 0) {
+			dev_dbg(host->dev, "failed receiving data\n");
+			goto out;
+		}
+	}
+
+	/* Indicate end of transfer, SEL goes up until next transfer */
+	gpio_set_value(host->sel_gpio, 1);
+	gpio_set_value(host->clk_gpio, 1);
+	gpio_set_value(host->clk_gpio, 0);
+
+out:
+	spin_unlock_irqrestore(&host->lock, flags);
+
+	return ret;
+}
+
+static int cbus_i2c_smbus_xfer(struct i2c_adapter	*adapter,
+			       u16			addr,
+			       unsigned short		flags,
+			       char			read_write,
+			       u8			command,
+			       int			size,
+			       union i2c_smbus_data	*data)
+{
+	struct cbus_host *chost = i2c_get_adapdata(adapter);
+	int ret;
+
+	if (size != I2C_SMBUS_WORD_DATA)
+		return -EINVAL;
+
+	ret = cbus_transfer(chost, read_write == I2C_SMBUS_READ, addr,
+			    command, data->word);
+	if (ret < 0)
+		return ret;
+
+	if (read_write == I2C_SMBUS_READ)
+		data->word = ret;
+
+	return 0;
+}
+
+static u32 cbus_i2c_func(struct i2c_adapter *adapter)
+{
+	return I2C_FUNC_SMBUS_READ_WORD_DATA | I2C_FUNC_SMBUS_WRITE_WORD_DATA;
+}
+
+static const struct i2c_algorithm cbus_i2c_algo = {
+	.smbus_xfer	= cbus_i2c_smbus_xfer,
+	.functionality	= cbus_i2c_func,
+};
+
+static int cbus_i2c_remove(struct platform_device *pdev)
+{
+	struct i2c_adapter *adapter = platform_get_drvdata(pdev);
+	struct cbus_host *chost = i2c_get_adapdata(adapter);
+	int ret;
+
+	ret = i2c_del_adapter(adapter);
+	if (ret)
+		return ret;
+	gpio_free(chost->clk_gpio);
+	gpio_free(chost->dat_gpio);
+	gpio_free(chost->sel_gpio);
+	kfree(chost);
+	kfree(adapter);
+	platform_set_drvdata(pdev, NULL);
+
+	return 0;
+}
+
+static int cbus_i2c_probe(struct platform_device *pdev)
+{
+	struct i2c_cbus_platform_data *pdata = pdev->dev.platform_data;
+	struct i2c_adapter *adapter;
+	struct cbus_host *chost;
+	struct gpio gpios[3];
+	int ret;
+
+	adapter = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL);
+	if (!adapter) {
+		ret = -ENOMEM;
+		goto error;
+	}
+
+	chost = kzalloc(sizeof(*chost), GFP_KERNEL);
+	if (!chost) {
+		ret = -ENOMEM;
+		goto error_mem;
+	}
+
+	adapter->owner		= THIS_MODULE;
+	adapter->class		= I2C_CLASS_HWMON;
+	adapter->dev.parent	= &pdev->dev;
+	adapter->nr		= pdev->id;
+	adapter->timeout	= HZ;
+	adapter->algo		= &cbus_i2c_algo;
+	strlcpy(adapter->name, "CBUS I2C adapter", sizeof(adapter->name));
+
+	spin_lock_init(&chost->lock);
+	chost->dev = &pdev->dev;
+
+	gpios[0].gpio  = chost->clk_gpio = pdata->clk_gpio;
+	gpios[0].flags = GPIOF_OUT_INIT_LOW;
+	gpios[0].label = "CBUS clk";
+
+	gpios[1].gpio  = chost->dat_gpio = pdata->dat_gpio;
+	gpios[1].flags = GPIOF_IN;
+	gpios[1].label = "CBUS data";
+
+	gpios[2].gpio  = chost->sel_gpio = pdata->sel_gpio;
+	gpios[2].flags = GPIOF_OUT_INIT_HIGH;
+	gpios[2].label = "CBUS sel";
+
+	ret = gpio_request_array(gpios, ARRAY_SIZE(gpios));
+	if (ret)
+		goto error_gpio;
+
+	gpio_set_value(chost->clk_gpio, 1);
+	gpio_set_value(chost->clk_gpio, 0);
+
+	i2c_set_adapdata(adapter, chost);
+	platform_set_drvdata(pdev, adapter);
+
+	ret = i2c_add_numbered_adapter(adapter);
+	if (ret)
+		goto error_i2c;
+
+	return 0;
+
+error_i2c:
+	gpio_free_array(gpios, ARRAY_SIZE(gpios));
+error_gpio:
+	kfree(chost);
+error_mem:
+	kfree(adapter);
+error:
+	return ret;
+}
+
+static struct platform_driver cbus_i2c_driver = {
+	.probe	= cbus_i2c_probe,
+	.remove	= cbus_i2c_remove,
+	.driver	= {
+		.owner	= THIS_MODULE,
+		.name	= "i2c-cbus",
+	},
+};
+module_platform_driver(cbus_i2c_driver);
+
+MODULE_ALIAS("platform:i2c-cbus");
+MODULE_DESCRIPTION("CBUS I2C driver");
+MODULE_AUTHOR("Juha Yrjölä");
+MODULE_AUTHOR("David Weinehall");
+MODULE_AUTHOR("Mikko Ylinen");
+MODULE_AUTHOR("Felipe Balbi <felipe.balbi@nokia.com>");
+MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@iki.fi>");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/i2c-cbus.h b/include/linux/i2c-cbus.h
new file mode 100644
index 0000000..636d726
--- /dev/null
+++ b/include/linux/i2c-cbus.h
@@ -0,0 +1,27 @@ 
+/*
+ * i2c-cbus.h - CBUS I2C platform_data definition
+ *
+ * Copyright (C) 2004-2009 Nokia Corporation
+ *
+ * Written by Felipe Balbi and Aaro Koskinen.
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file "COPYING" in the main directory of this
+ * archive for more details.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __INCLUDE_LINUX_I2C_CBUS_H
+#define __INCLUDE_LINUX_I2C_CBUS_H
+
+struct i2c_cbus_platform_data {
+	int dat_gpio;
+	int clk_gpio;
+	int sel_gpio;
+};
+
+#endif /* __INCLUDE_LINUX_I2C_CBUS_H */