/*
   *  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
  ");
  		return -EREMOTEIO;
  	}
  
  	dev_dbg(&i2c->dev, "  status = %d
  ", status->status);
  	if (status->status != 0x00) {
  		dev_err(&i2c->dev, "failure: i2c protocol error
  ");
  		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
  ");
  		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
  ");
  		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
  ");
  		return -EREMOTEIO;
  	}
  	return 0;
  }
  
  static int vprbrd_i2c_read(struct vprbrd *vb, struct i2c_msg *msg)
  {
  	int ret;
  	u16 remain_len, 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;
  			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:
  ", num);
  
  	for (i = 0 ; i < num ; i++) {
  		pmsg = &msgs[i];
  
  		dev_dbg(&i2c->dev,
  			"  %d: %s (flags %d) %d bytes to 0x%02x
  ",
  			i, pmsg->flags & I2C_M_RD ? "read" : "write",
  			pmsg->flags, pmsg->len, pmsg->addr);
  
  		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 struct i2c_adapter_quirks vprbrd_quirks = {
  	.max_read_len = 2048,
  	.max_write_len = 2048,
  };
  
  static int 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 = devm_kzalloc(&pdev->dev, 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.quirks = &vprbrd_quirks;
  	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
  ",
  				i2c_bus_freq);
  			return -EIO;
  		}
  	} else {
  		dev_err(&pdev->dev,
  			"invalid i2c_bus_freq setting:%d
  ", i2c_bus_freq);
  		return -EIO;
  	}
  
  	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;
  }
  
  static int vprbrd_i2c_remove(struct platform_device *pdev)
  {
  	struct vprbrd_i2c *vb_i2c = platform_get_drvdata(pdev);
  
  	i2c_del_adapter(&vb_i2c->i2c);
  
  	return 0;
  }
  
  static struct platform_driver vprbrd_i2c_driver = {
  	.driver.name	= "viperboard-i2c",
  	.driver.owner	= THIS_MODULE,
  	.probe		= vprbrd_i2c_probe,
  	.remove		= 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)
  ", 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");