drivers/i2c/busses/i2c-viperboard.c - LeafOS-Devices/android_kernel_samsung_gta4xl - Gitiles

 /*
  *  Nano River Technologies viperboard i2c master driver
  *
  *  (C) 2012 by Lemonage GmbH
  *  Author: Lars Poeschel <poeschel@lemonage.de>
  *  All rights reserved.
  *
  *  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.
  *
  */

 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/mutex.h>
 #include <linux/platform_device.h>

 #include <linux/usb.h>
 #include <linux/i2c.h>

 #include <linux/mfd/viperboard.h>

 struct vprbrd_i2c {
 	struct i2c_adapter i2c;
 	u8 bus_freq_param;
 };

 /* i2c bus frequency module parameter */
 static u8 i2c_bus_param;
 static unsigned int i2c_bus_freq = 100;
 module_param(i2c_bus_freq, int, 0);
 MODULE_PARM_DESC(i2c_bus_freq,
 	"i2c bus frequency in khz (default is 100) valid values: 10, 100, 200, 400, 1000, 3000, 6000");

 static int vprbrd_i2c_status(struct i2c_adapter *i2c,
 	struct vprbrd_i2c_status *status, bool prev_error)
 {
 	u16 bytes_xfer;
 	int ret;
 	struct vprbrd *vb = (struct vprbrd *)i2c->algo_data;

 	/* check for protocol error */
 	bytes_xfer = sizeof(struct vprbrd_i2c_status);

 	ret = usb_control_msg(vb->usb_dev, usb_rcvctrlpipe(vb->usb_dev, 0),
 		VPRBRD_USB_REQUEST_I2C, VPRBRD_USB_TYPE_IN, 0x0000, 0x0000,
 		status, bytes_xfer, VPRBRD_USB_TIMEOUT_MS);

 	if (ret != bytes_xfer)
 		prev_error = true;

 	if (prev_error) {
 		dev_err(&i2c->dev, "failure in usb communication\n");
 		return -EREMOTEIO;
 	}

 	dev_dbg(&i2c->dev, "  status = %d\n", status->status);
 	if (status->status != 0x00) {
 		dev_err(&i2c->dev, "failure: i2c protocol error\n");
 		return -EPROTO;
 	}
 	return 0;
 }

 static int vprbrd_i2c_receive(struct usb_device *usb_dev,
 	struct vprbrd_i2c_read_msg *rmsg, int bytes_xfer)
 {
 	int ret, bytes_actual;
 	int error = 0;

 	/* send the read request */
 	ret = usb_bulk_msg(usb_dev,
 		usb_sndbulkpipe(usb_dev, VPRBRD_EP_OUT), rmsg,
 		sizeof(struct vprbrd_i2c_read_hdr), &bytes_actual,
 		VPRBRD_USB_TIMEOUT_MS);

 	if ((ret < 0)
 		|| (bytes_actual != sizeof(struct vprbrd_i2c_read_hdr))) {
 		dev_err(&usb_dev->dev, "failure transmitting usb\n");
 		error = -EREMOTEIO;
 	}

 	/* read the actual data */
 	ret = usb_bulk_msg(usb_dev,
 		usb_rcvbulkpipe(usb_dev, VPRBRD_EP_IN), rmsg,
 		bytes_xfer, &bytes_actual, VPRBRD_USB_TIMEOUT_MS);

 	if ((ret < 0) || (bytes_xfer != bytes_actual)) {
 		dev_err(&usb_dev->dev, "failure receiving usb\n");
 		error = -EREMOTEIO;
 	}
 	return error;
 }

 static int vprbrd_i2c_addr(struct usb_device *usb_dev,
 	struct vprbrd_i2c_addr_msg *amsg)
 {
 	int ret, bytes_actual;

 	ret = usb_bulk_msg(usb_dev,
 		usb_sndbulkpipe(usb_dev, VPRBRD_EP_OUT), amsg,
 		sizeof(struct vprbrd_i2c_addr_msg), &bytes_actual,
 		VPRBRD_USB_TIMEOUT_MS);

 	if ((ret < 0) ||
 			(sizeof(struct vprbrd_i2c_addr_msg) != bytes_actual)) {
 		dev_err(&usb_dev->dev, "failure transmitting usb\n");
 		return -EREMOTEIO;
 	}
 	return 0;
 }

 static int vprbrd_i2c_read(struct vprbrd *vb, struct i2c_msg *msg)
 {
 	int ret;
 	u16 remain_len, bytes_xfer, len1, len2,
 		start = 0x0000;
 	struct vprbrd_i2c_read_msg *rmsg =
 		(struct vprbrd_i2c_read_msg *)vb->buf;

 	remain_len = msg->len;
 	rmsg->header.cmd = VPRBRD_I2C_CMD_READ;
 	while (remain_len > 0) {
 		rmsg->header.addr = cpu_to_le16(start + 0x4000);
 		if (remain_len <= 255) {
 			len1 = remain_len;
 			len2 = 0x00;
 			rmsg->header.len0 = remain_len;
 			rmsg->header.len1 = 0x00;
 			rmsg->header.len2 = 0x00;
 			rmsg->header.len3 = 0x00;
 			rmsg->header.len4 = 0x00;
 			rmsg->header.len5 = 0x00;
 			remain_len = 0;
 		} else if (remain_len <= 510) {
 			len1 = remain_len;
 			len2 = 0x00;
 			rmsg->header.len0 = remain_len - 255;
 			rmsg->header.len1 = 0xff;
 			rmsg->header.len2 = 0x00;
 			rmsg->header.len3 = 0x00;
 			rmsg->header.len4 = 0x00;
 			rmsg->header.len5 = 0x00;
 			remain_len = 0;
 		} else if (remain_len <= 512) {
 			len1 = remain_len;
 			len2 = 0x00;
 			rmsg->header.len0 = remain_len - 510;
 			rmsg->header.len1 = 0xff;
 			rmsg->header.len2 = 0xff;
 			rmsg->header.len3 = 0x00;
 			rmsg->header.len4 = 0x00;
 			rmsg->header.len5 = 0x00;
 			remain_len = 0;
 		} else if (remain_len <= 767) {
 			len1 = 512;
 			len2 = remain_len - 512;
 			rmsg->header.len0 = 0x02;
 			rmsg->header.len1 = 0xff;
 			rmsg->header.len2 = 0xff;
 			rmsg->header.len3 = remain_len - 512;
 			rmsg->header.len4 = 0x00;
 			rmsg->header.len5 = 0x00;
 			bytes_xfer = remain_len;
 			remain_len = 0;
 		} else if (remain_len <= 1022) {
 			len1 = 512;
 			len2 = remain_len - 512;
 			rmsg->header.len0 = 0x02;
 			rmsg->header.len1 = 0xff;
 			rmsg->header.len2 = 0xff;
 			rmsg->header.len3 = remain_len - 767;
 			rmsg->header.len4 = 0xff;
 			rmsg->header.len5 = 0x00;
 			remain_len = 0;
 		} else if (remain_len <= 1024) {
 			len1 = 512;
 			len2 = remain_len - 512;
 			rmsg->header.len0 = 0x02;
 			rmsg->header.len1 = 0xff;
 			rmsg->header.len2 = 0xff;
 			rmsg->header.len3 = remain_len - 1022;
 			rmsg->header.len4 = 0xff;
 			rmsg->header.len5 = 0xff;
 			remain_len = 0;
 		} else {
 			len1 = 512;
 			len2 = 512;
 			rmsg->header.len0 = 0x02;
 			rmsg->header.len1 = 0xff;
 			rmsg->header.len2 = 0xff;
 			rmsg->header.len3 = 0x02;
 			rmsg->header.len4 = 0xff;
 			rmsg->header.len5 = 0xff;
 			remain_len -= 1024;
 			start += 1024;
 		}
 		rmsg->header.tf1 = cpu_to_le16(len1);
 		rmsg->header.tf2 = cpu_to_le16(len2);

 		/* first read transfer */
 		ret = vprbrd_i2c_receive(vb->usb_dev, rmsg, len1);
 		if (ret < 0)
 			return ret;
 		/* copy the received data */
 		memcpy(msg->buf + start, rmsg, len1);

 		/* second read transfer if neccessary */
 		if (len2 > 0) {
 			ret = vprbrd_i2c_receive(vb->usb_dev, rmsg, len2);
 			if (ret < 0)
 				return ret;
 			/* copy the received data */
 			memcpy(msg->buf + start + 512, rmsg, len2);
 		}
 	}
 	return 0;
 }

 static int vprbrd_i2c_write(struct vprbrd *vb, struct i2c_msg *msg)
 {
 	int ret, bytes_actual;
 	u16 remain_len, bytes_xfer,
 		start = 0x0000;
 	struct vprbrd_i2c_write_msg *wmsg =
 		(struct vprbrd_i2c_write_msg *)vb->buf;

 	remain_len = msg->len;
 	wmsg->header.cmd = VPRBRD_I2C_CMD_WRITE;
 	wmsg->header.last = 0x00;
 	wmsg->header.chan = 0x00;
 	wmsg->header.spi = 0x0000;
 	while (remain_len > 0) {
 		wmsg->header.addr = cpu_to_le16(start + 0x4000);
 		if (remain_len > 503) {
 			wmsg->header.len1 = 0xff;
 			wmsg->header.len2 = 0xf8;
 			remain_len -= 503;
 			bytes_xfer = 503 + sizeof(struct vprbrd_i2c_write_hdr);
 			start += 503;
 		} else if (remain_len > 255) {
 			wmsg->header.len1 = 0xff;
 			wmsg->header.len2 = (remain_len - 255);
 			bytes_xfer = remain_len +
 				sizeof(struct vprbrd_i2c_write_hdr);
 			remain_len = 0;
 		} else {
 			wmsg->header.len1 = remain_len;
 			wmsg->header.len2 = 0x00;
 			bytes_xfer = remain_len +
 				sizeof(struct vprbrd_i2c_write_hdr);
 			remain_len = 0;
 		}
 		memcpy(wmsg->data, msg->buf + start,
 			bytes_xfer - sizeof(struct vprbrd_i2c_write_hdr));

 		ret = usb_bulk_msg(vb->usb_dev,
 			usb_sndbulkpipe(vb->usb_dev,
 			VPRBRD_EP_OUT), wmsg,
 			bytes_xfer, &bytes_actual, VPRBRD_USB_TIMEOUT_MS);
 		if ((ret < 0) || (bytes_xfer != bytes_actual))
 			return -EREMOTEIO;
 	}
 	return 0;
 }

 static int vprbrd_i2c_xfer(struct i2c_adapter *i2c, struct i2c_msg *msgs,
 		int num)
 {
 	struct i2c_msg *pmsg;
 	int i, ret,
 		error = 0;
 	struct vprbrd *vb = (struct vprbrd *)i2c->algo_data;
 	struct vprbrd_i2c_addr_msg *amsg =
 		(struct vprbrd_i2c_addr_msg *)vb->buf;
 	struct vprbrd_i2c_status *smsg = (struct vprbrd_i2c_status *)vb->buf;

 	dev_dbg(&i2c->dev, "master xfer %d messages:\n", num);

 	for (i = 0 ; i < num ; i++) {
 		pmsg = &msgs[i];

 		dev_dbg(&i2c->dev,
 			"  %d: %s (flags %d) %d bytes to 0x%02x\n",
 			i, pmsg->flags & I2C_M_RD ? "read" : "write",
 			pmsg->flags, pmsg->len, pmsg->addr);

 		/* msgs longer than 2048 bytes are not supported by adapter */
 		if (pmsg->len > 2048)
 			return -EINVAL;

 		mutex_lock(&vb->lock);
 		/* directly send the message */
 		if (pmsg->flags & I2C_M_RD) {
 			/* read data */
 			amsg->cmd = VPRBRD_I2C_CMD_ADDR;
 			amsg->unknown2 = 0x00;
 			amsg->unknown3 = 0x00;
 			amsg->addr = pmsg->addr;
 			amsg->unknown1 = 0x01;
 			amsg->len = cpu_to_le16(pmsg->len);
 			/* send the addr and len, we're interested to board */
 			ret = vprbrd_i2c_addr(vb->usb_dev, amsg);
 			if (ret < 0)
 				error = ret;

 			ret = vprbrd_i2c_read(vb, pmsg);
 			if (ret < 0)
 				error = ret;

 			ret = vprbrd_i2c_status(i2c, smsg, error);
 			if (ret < 0)
 				error = ret;
 			/* in case of protocol error, return the error */
 			if (error < 0)
 				goto error;
 		} else {
 			/* write data */
 			ret = vprbrd_i2c_write(vb, pmsg);

 			amsg->cmd = VPRBRD_I2C_CMD_ADDR;
 			amsg->unknown2 = 0x00;
 			amsg->unknown3 = 0x00;
 			amsg->addr = pmsg->addr;
 			amsg->unknown1 = 0x00;
 			amsg->len = cpu_to_le16(pmsg->len);
 			/* send the addr, the data goes to to board */
 			ret = vprbrd_i2c_addr(vb->usb_dev, amsg);
 			if (ret < 0)
 				error = ret;

 			ret = vprbrd_i2c_status(i2c, smsg, error);
 			if (ret < 0)
 				error = ret;

 			if (error < 0)
 				goto error;
 		}
 		mutex_unlock(&vb->lock);
 	}
 	return 0;
 error:
 	mutex_unlock(&vb->lock);
 	return error;
 }

 static u32 vprbrd_i2c_func(struct i2c_adapter *i2c)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 }

 /* This is the actual algorithm we define */
 static const struct i2c_algorithm vprbrd_algorithm = {
 	.master_xfer	= vprbrd_i2c_xfer,
 	.functionality	= vprbrd_i2c_func,
 };

 static int __devinit vprbrd_i2c_probe(struct platform_device *pdev)
 {
 	struct vprbrd *vb = dev_get_drvdata(pdev->dev.parent);
 	struct vprbrd_i2c *vb_i2c;
 	int ret;
 	int pipe;

 	vb_i2c = kzalloc(sizeof(*vb_i2c), GFP_KERNEL);
 	if (vb_i2c == NULL)
 		return -ENOMEM;

 	/* setup i2c adapter description */
 	vb_i2c->i2c.owner = THIS_MODULE;
 	vb_i2c->i2c.class = I2C_CLASS_HWMON;
 	vb_i2c->i2c.algo = &vprbrd_algorithm;
 	vb_i2c->i2c.algo_data = vb;
 	/* save the param in usb capabable memory */
 	vb_i2c->bus_freq_param = i2c_bus_param;

 	snprintf(vb_i2c->i2c.name, sizeof(vb_i2c->i2c.name),
 		 "viperboard at bus %03d device %03d",
 		 vb->usb_dev->bus->busnum, vb->usb_dev->devnum);

 	/* setting the bus frequency */
 	if ((i2c_bus_param <= VPRBRD_I2C_FREQ_10KHZ)
 		&& (i2c_bus_param >= VPRBRD_I2C_FREQ_6MHZ)) {
 		pipe = usb_sndctrlpipe(vb->usb_dev, 0);
 		ret = usb_control_msg(vb->usb_dev, pipe,
 			VPRBRD_USB_REQUEST_I2C_FREQ, VPRBRD_USB_TYPE_OUT,
 			0x0000, 0x0000, &vb_i2c->bus_freq_param, 1,
 			VPRBRD_USB_TIMEOUT_MS);
 	    if (ret != 1) {
 		dev_err(&pdev->dev,
 			"failure setting i2c_bus_freq to %d\n", i2c_bus_freq);
 		ret = -EIO;
 		goto error;
 	    }
 	} else {
 		dev_err(&pdev->dev,
 			"invalid i2c_bus_freq setting:%d\n", i2c_bus_freq);
 		ret = -EIO;
 		goto error;
 	}

 	vb_i2c->i2c.dev.parent = &pdev->dev;

 	/* attach to i2c layer */
 	i2c_add_adapter(&vb_i2c->i2c);

 	platform_set_drvdata(pdev, vb_i2c);

 	return 0;

 error:
 	kfree(vb_i2c);
 	return ret;
 }

 static int __devexit vprbrd_i2c_remove(struct platform_device *pdev)
 {
 	struct vprbrd_i2c *vb_i2c = platform_get_drvdata(pdev);
 	int ret;

 	ret = i2c_del_adapter(&vb_i2c->i2c);

 	return ret;
 }

 static struct platform_driver vprbrd_i2c_driver = {
 	.driver.name	= "viperboard-i2c",
 	.driver.owner	= THIS_MODULE,
 	.probe		= vprbrd_i2c_probe,
 	.remove		= __devexit_p(vprbrd_i2c_remove),
 };

 static int __init vprbrd_i2c_init(void)
 {
 	switch (i2c_bus_freq) {
 	case 6000:
 		i2c_bus_param = VPRBRD_I2C_FREQ_6MHZ;
 		break;
 	case 3000:
 		i2c_bus_param = VPRBRD_I2C_FREQ_3MHZ;
 		break;
 	case 1000:
 		i2c_bus_param = VPRBRD_I2C_FREQ_1MHZ;
 		break;
 	case 400:
 		i2c_bus_param = VPRBRD_I2C_FREQ_400KHZ;
 		break;
 	case 200:
 		i2c_bus_param = VPRBRD_I2C_FREQ_200KHZ;
 		break;
 	case 100:
 		i2c_bus_param = VPRBRD_I2C_FREQ_100KHZ;
 		break;
 	case 10:
 		i2c_bus_param = VPRBRD_I2C_FREQ_10KHZ;
 		break;
 	default:
 		pr_warn("invalid i2c_bus_freq (%d)\n", i2c_bus_freq);
 		i2c_bus_param = VPRBRD_I2C_FREQ_100KHZ;
 	}

 	return platform_driver_register(&vprbrd_i2c_driver);
 }
 subsys_initcall(vprbrd_i2c_init);

 static void __exit vprbrd_i2c_exit(void)
 {
 	platform_driver_unregister(&vprbrd_i2c_driver);
 }
 module_exit(vprbrd_i2c_exit);

 MODULE_AUTHOR("Lars Poeschel <poeschel@lemonage.de>");
 MODULE_DESCRIPTION("I2C master driver for Nano River Techs Viperboard");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:viperboard-i2c");
	/*
	* Nano River Technologies viperboard i2c master driver
	*
	* (C) 2012 by Lemonage GmbH
	* Author: Lars Poeschel <poeschel@lemonage.de>
	* All rights reserved.
	*
	* 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.
	*
	*/

	#include <linux/kernel.h>
	#include <linux/errno.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/types.h>
	#include <linux/mutex.h>
	#include <linux/platform_device.h>

	#include <linux/usb.h>
	#include <linux/i2c.h>

	#include <linux/mfd/viperboard.h>

	struct vprbrd_i2c {
	struct i2c_adapter i2c;
	u8 bus_freq_param;
	};

	/* i2c bus frequency module parameter */
	static u8 i2c_bus_param;
	static unsigned int i2c_bus_freq = 100;
	module_param(i2c_bus_freq, int, 0);
	MODULE_PARM_DESC(i2c_bus_freq,
	"i2c bus frequency in khz (default is 100) valid values: 10, 100, 200, 400, 1000, 3000, 6000");

	static int vprbrd_i2c_status(struct i2c_adapter *i2c,
	struct vprbrd_i2c_status *status, bool prev_error)
	{
	u16 bytes_xfer;
	int ret;
	struct vprbrd vb = (struct vprbrd )i2c->algo_data;

	/* check for protocol error */
	bytes_xfer = sizeof(struct vprbrd_i2c_status);

	ret = usb_control_msg(vb->usb_dev, usb_rcvctrlpipe(vb->usb_dev, 0),
	VPRBRD_USB_REQUEST_I2C, VPRBRD_USB_TYPE_IN, 0x0000, 0x0000,
	status, bytes_xfer, VPRBRD_USB_TIMEOUT_MS);

	if (ret != bytes_xfer)
	prev_error = true;

	if (prev_error) {
	dev_err(&i2c->dev, "failure in usb communication\n");
	return -EREMOTEIO;
	}

	dev_dbg(&i2c->dev, " status = %d\n", status->status);
	if (status->status != 0x00) {
	dev_err(&i2c->dev, "failure: i2c protocol error\n");
	return -EPROTO;
	}
	return 0;
	}

	static int vprbrd_i2c_receive(struct usb_device *usb_dev,
	struct vprbrd_i2c_read_msg *rmsg, int bytes_xfer)
	{
	int ret, bytes_actual;
	int error = 0;

	/* send the read request */
	ret = usb_bulk_msg(usb_dev,
	usb_sndbulkpipe(usb_dev, VPRBRD_EP_OUT), rmsg,
	sizeof(struct vprbrd_i2c_read_hdr), &bytes_actual,
	VPRBRD_USB_TIMEOUT_MS);

	if ((ret < 0)
	\|\| (bytes_actual != sizeof(struct vprbrd_i2c_read_hdr))) {
	dev_err(&usb_dev->dev, "failure transmitting usb\n");
	error = -EREMOTEIO;
	}

	/* read the actual data */
	ret = usb_bulk_msg(usb_dev,
	usb_rcvbulkpipe(usb_dev, VPRBRD_EP_IN), rmsg,
	bytes_xfer, &bytes_actual, VPRBRD_USB_TIMEOUT_MS);

	if ((ret < 0) \|\| (bytes_xfer != bytes_actual)) {
	dev_err(&usb_dev->dev, "failure receiving usb\n");
	error = -EREMOTEIO;
	}
	return error;
	}

	static int vprbrd_i2c_addr(struct usb_device *usb_dev,
	struct vprbrd_i2c_addr_msg *amsg)
	{
	int ret, bytes_actual;

	ret = usb_bulk_msg(usb_dev,
	usb_sndbulkpipe(usb_dev, VPRBRD_EP_OUT), amsg,
	sizeof(struct vprbrd_i2c_addr_msg), &bytes_actual,
	VPRBRD_USB_TIMEOUT_MS);

	if ((ret < 0) \|\|
	(sizeof(struct vprbrd_i2c_addr_msg) != bytes_actual)) {
	dev_err(&usb_dev->dev, "failure transmitting usb\n");
	return -EREMOTEIO;
	}
	return 0;
	}

	static int vprbrd_i2c_read(struct vprbrd vb, struct i2c_msg msg)
	{
	int ret;
	u16 remain_len, bytes_xfer, len1, len2,
	start = 0x0000;
	struct vprbrd_i2c_read_msg *rmsg =
	(struct vprbrd_i2c_read_msg *)vb->buf;

	remain_len = msg->len;
	rmsg->header.cmd = VPRBRD_I2C_CMD_READ;
	while (remain_len > 0) {
	rmsg->header.addr = cpu_to_le16(start + 0x4000);
	if (remain_len <= 255) {
	len1 = remain_len;
	len2 = 0x00;
	rmsg->header.len0 = remain_len;
	rmsg->header.len1 = 0x00;
	rmsg->header.len2 = 0x00;
	rmsg->header.len3 = 0x00;
	rmsg->header.len4 = 0x00;
	rmsg->header.len5 = 0x00;
	remain_len = 0;
	} else if (remain_len <= 510) {
	len1 = remain_len;
	len2 = 0x00;
	rmsg->header.len0 = remain_len - 255;
	rmsg->header.len1 = 0xff;
	rmsg->header.len2 = 0x00;
	rmsg->header.len3 = 0x00;
	rmsg->header.len4 = 0x00;
	rmsg->header.len5 = 0x00;
	remain_len = 0;
	} else if (remain_len <= 512) {
	len1 = remain_len;
	len2 = 0x00;
	rmsg->header.len0 = remain_len - 510;
	rmsg->header.len1 = 0xff;
	rmsg->header.len2 = 0xff;
	rmsg->header.len3 = 0x00;
	rmsg->header.len4 = 0x00;
	rmsg->header.len5 = 0x00;
	remain_len = 0;
	} else if (remain_len <= 767) {
	len1 = 512;
	len2 = remain_len - 512;
	rmsg->header.len0 = 0x02;
	rmsg->header.len1 = 0xff;
	rmsg->header.len2 = 0xff;
	rmsg->header.len3 = remain_len - 512;
	rmsg->header.len4 = 0x00;
	rmsg->header.len5 = 0x00;
	bytes_xfer = remain_len;
	remain_len = 0;
	} else if (remain_len <= 1022) {
	len1 = 512;
	len2 = remain_len - 512;
	rmsg->header.len0 = 0x02;
	rmsg->header.len1 = 0xff;
	rmsg->header.len2 = 0xff;
	rmsg->header.len3 = remain_len - 767;
	rmsg->header.len4 = 0xff;
	rmsg->header.len5 = 0x00;
	remain_len = 0;
	} else if (remain_len <= 1024) {
	len1 = 512;
	len2 = remain_len - 512;
	rmsg->header.len0 = 0x02;
	rmsg->header.len1 = 0xff;
	rmsg->header.len2 = 0xff;
	rmsg->header.len3 = remain_len - 1022;
	rmsg->header.len4 = 0xff;
	rmsg->header.len5 = 0xff;
	remain_len = 0;
	} else {
	len1 = 512;
	len2 = 512;
	rmsg->header.len0 = 0x02;
	rmsg->header.len1 = 0xff;
	rmsg->header.len2 = 0xff;
	rmsg->header.len3 = 0x02;
	rmsg->header.len4 = 0xff;
	rmsg->header.len5 = 0xff;
	remain_len -= 1024;
	start += 1024;
	}
	rmsg->header.tf1 = cpu_to_le16(len1);
	rmsg->header.tf2 = cpu_to_le16(len2);

	/* first read transfer */
	ret = vprbrd_i2c_receive(vb->usb_dev, rmsg, len1);
	if (ret < 0)
	return ret;
	/* copy the received data */
	memcpy(msg->buf + start, rmsg, len1);

	/* second read transfer if neccessary */
	if (len2 > 0) {
	ret = vprbrd_i2c_receive(vb->usb_dev, rmsg, len2);
	if (ret < 0)
	return ret;
	/* copy the received data */
	memcpy(msg->buf + start + 512, rmsg, len2);
	}
	}
	return 0;
	}

	static int vprbrd_i2c_write(struct vprbrd vb, struct i2c_msg msg)
	{
	int ret, bytes_actual;
	u16 remain_len, bytes_xfer,
	start = 0x0000;
	struct vprbrd_i2c_write_msg *wmsg =
	(struct vprbrd_i2c_write_msg *)vb->buf;

	remain_len = msg->len;
	wmsg->header.cmd = VPRBRD_I2C_CMD_WRITE;
	wmsg->header.last = 0x00;
	wmsg->header.chan = 0x00;
	wmsg->header.spi = 0x0000;
	while (remain_len > 0) {
	wmsg->header.addr = cpu_to_le16(start + 0x4000);
	if (remain_len > 503) {
	wmsg->header.len1 = 0xff;
	wmsg->header.len2 = 0xf8;
	remain_len -= 503;
	bytes_xfer = 503 + sizeof(struct vprbrd_i2c_write_hdr);
	start += 503;
	} else if (remain_len > 255) {
	wmsg->header.len1 = 0xff;
	wmsg->header.len2 = (remain_len - 255);
	bytes_xfer = remain_len +
	sizeof(struct vprbrd_i2c_write_hdr);
	remain_len = 0;
	} else {
	wmsg->header.len1 = remain_len;
	wmsg->header.len2 = 0x00;
	bytes_xfer = remain_len +
	sizeof(struct vprbrd_i2c_write_hdr);
	remain_len = 0;
	}
	memcpy(wmsg->data, msg->buf + start,
	bytes_xfer - sizeof(struct vprbrd_i2c_write_hdr));

	ret = usb_bulk_msg(vb->usb_dev,
	usb_sndbulkpipe(vb->usb_dev,
	VPRBRD_EP_OUT), wmsg,
	bytes_xfer, &bytes_actual, VPRBRD_USB_TIMEOUT_MS);
	if ((ret < 0) \|\| (bytes_xfer != bytes_actual))
	return -EREMOTEIO;
	}
	return 0;
	}

	static int vprbrd_i2c_xfer(struct i2c_adapter i2c, struct i2c_msg msgs,
	int num)
	{
	struct i2c_msg *pmsg;
	int i, ret,
	error = 0;
	struct vprbrd vb = (struct vprbrd )i2c->algo_data;
	struct vprbrd_i2c_addr_msg *amsg =
	(struct vprbrd_i2c_addr_msg *)vb->buf;
	struct vprbrd_i2c_status smsg = (struct vprbrd_i2c_status )vb->buf;

	dev_dbg(&i2c->dev, "master xfer %d messages:\n", num);

	for (i = 0 ; i < num ; i++) {
	pmsg = &msgs[i];

	dev_dbg(&i2c->dev,
	" %d: %s (flags %d) %d bytes to 0x%02x\n",
	i, pmsg->flags & I2C_M_RD ? "read" : "write",
	pmsg->flags, pmsg->len, pmsg->addr);

	/* msgs longer than 2048 bytes are not supported by adapter */
	if (pmsg->len > 2048)
	return -EINVAL;

	mutex_lock(&vb->lock);
	/* directly send the message */
	if (pmsg->flags & I2C_M_RD) {
	/* read data */
	amsg->cmd = VPRBRD_I2C_CMD_ADDR;
	amsg->unknown2 = 0x00;
	amsg->unknown3 = 0x00;
	amsg->addr = pmsg->addr;
	amsg->unknown1 = 0x01;
	amsg->len = cpu_to_le16(pmsg->len);
	/* send the addr and len, we're interested to board */
	ret = vprbrd_i2c_addr(vb->usb_dev, amsg);
	if (ret < 0)
	error = ret;

	ret = vprbrd_i2c_read(vb, pmsg);
	if (ret < 0)
	error = ret;

	ret = vprbrd_i2c_status(i2c, smsg, error);
	if (ret < 0)
	error = ret;
	/* in case of protocol error, return the error */
	if (error < 0)
	goto error;
	} else {
	/* write data */
	ret = vprbrd_i2c_write(vb, pmsg);

	amsg->cmd = VPRBRD_I2C_CMD_ADDR;
	amsg->unknown2 = 0x00;
	amsg->unknown3 = 0x00;
	amsg->addr = pmsg->addr;
	amsg->unknown1 = 0x00;
	amsg->len = cpu_to_le16(pmsg->len);
	/* send the addr, the data goes to to board */
	ret = vprbrd_i2c_addr(vb->usb_dev, amsg);
	if (ret < 0)
	error = ret;

	ret = vprbrd_i2c_status(i2c, smsg, error);
	if (ret < 0)
	error = ret;

	if (error < 0)
	goto error;
	}
	mutex_unlock(&vb->lock);
	}
	return 0;
	error:
	mutex_unlock(&vb->lock);
	return error;
	}

	static u32 vprbrd_i2c_func(struct i2c_adapter *i2c)
	{
	return I2C_FUNC_I2C \| I2C_FUNC_SMBUS_EMUL;
	}

	/* This is the actual algorithm we define */
	static const struct i2c_algorithm vprbrd_algorithm = {
	.master_xfer = vprbrd_i2c_xfer,
	.functionality = vprbrd_i2c_func,
	};

	static int __devinit vprbrd_i2c_probe(struct platform_device *pdev)
	{
	struct vprbrd *vb = dev_get_drvdata(pdev->dev.parent);
	struct vprbrd_i2c *vb_i2c;
	int ret;
	int pipe;

	vb_i2c = kzalloc(sizeof(*vb_i2c), GFP_KERNEL);
	if (vb_i2c == NULL)
	return -ENOMEM;

	/* setup i2c adapter description */
	vb_i2c->i2c.owner = THIS_MODULE;
	vb_i2c->i2c.class = I2C_CLASS_HWMON;
	vb_i2c->i2c.algo = &vprbrd_algorithm;
	vb_i2c->i2c.algo_data = vb;
	/* save the param in usb capabable memory */
	vb_i2c->bus_freq_param = i2c_bus_param;

	snprintf(vb_i2c->i2c.name, sizeof(vb_i2c->i2c.name),
	"viperboard at bus %03d device %03d",
	vb->usb_dev->bus->busnum, vb->usb_dev->devnum);

	/* setting the bus frequency */
	if ((i2c_bus_param <= VPRBRD_I2C_FREQ_10KHZ)
	&& (i2c_bus_param >= VPRBRD_I2C_FREQ_6MHZ)) {
	pipe = usb_sndctrlpipe(vb->usb_dev, 0);
	ret = usb_control_msg(vb->usb_dev, pipe,
	VPRBRD_USB_REQUEST_I2C_FREQ, VPRBRD_USB_TYPE_OUT,
	0x0000, 0x0000, &vb_i2c->bus_freq_param, 1,
	VPRBRD_USB_TIMEOUT_MS);
	if (ret != 1) {
	dev_err(&pdev->dev,
	"failure setting i2c_bus_freq to %d\n", i2c_bus_freq);
	ret = -EIO;
	goto error;
	}
	} else {
	dev_err(&pdev->dev,
	"invalid i2c_bus_freq setting:%d\n", i2c_bus_freq);
	ret = -EIO;
	goto error;
	}

	vb_i2c->i2c.dev.parent = &pdev->dev;

	/* attach to i2c layer */
	i2c_add_adapter(&vb_i2c->i2c);

	platform_set_drvdata(pdev, vb_i2c);

	return 0;

	error:
	kfree(vb_i2c);
	return ret;
	}

	static int __devexit vprbrd_i2c_remove(struct platform_device *pdev)
	{
	struct vprbrd_i2c *vb_i2c = platform_get_drvdata(pdev);
	int ret;

	ret = i2c_del_adapter(&vb_i2c->i2c);

	return ret;
	}

	static struct platform_driver vprbrd_i2c_driver = {
	.driver.name = "viperboard-i2c",
	.driver.owner = THIS_MODULE,
	.probe = vprbrd_i2c_probe,
	.remove = __devexit_p(vprbrd_i2c_remove),
	};

	static int __init vprbrd_i2c_init(void)
	{
	switch (i2c_bus_freq) {
	case 6000:
	i2c_bus_param = VPRBRD_I2C_FREQ_6MHZ;
	break;
	case 3000:
	i2c_bus_param = VPRBRD_I2C_FREQ_3MHZ;
	break;
	case 1000:
	i2c_bus_param = VPRBRD_I2C_FREQ_1MHZ;
	break;
	case 400:
	i2c_bus_param = VPRBRD_I2C_FREQ_400KHZ;
	break;
	case 200:
	i2c_bus_param = VPRBRD_I2C_FREQ_200KHZ;
	break;
	case 100:
	i2c_bus_param = VPRBRD_I2C_FREQ_100KHZ;
	break;
	case 10:
	i2c_bus_param = VPRBRD_I2C_FREQ_10KHZ;
	break;
	default:
	pr_warn("invalid i2c_bus_freq (%d)\n", i2c_bus_freq);
	i2c_bus_param = VPRBRD_I2C_FREQ_100KHZ;
	}

	return platform_driver_register(&vprbrd_i2c_driver);
	}
	subsys_initcall(vprbrd_i2c_init);

	static void __exit vprbrd_i2c_exit(void)
	{
	platform_driver_unregister(&vprbrd_i2c_driver);
	}
	module_exit(vprbrd_i2c_exit);

	MODULE_AUTHOR("Lars Poeschel <poeschel@lemonage.de>");
	MODULE_DESCRIPTION("I2C master driver for Nano River Techs Viperboard");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:viperboard-i2c");