drivers/i2c/busses/i2c-bfin-twi.c - third_party/linux - Git at Google

 /*
  * drivers/i2c/busses/i2c-bfin-twi.c
  *
  * Description: Driver for Blackfin Two Wire Interface
  *
  * Author:      sonicz  <sonic.zhang@analog.com>
  *
  * Copyright (c) 2005-2007 Analog Devices, Inc.
  *
  * 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.
  *
  * 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.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */

 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/i2c.h>
 #include <linux/mm.h>
 #include <linux/timer.h>
 #include <linux/spinlock.h>
 #include <linux/completion.h>
 #include <linux/interrupt.h>
 #include <linux/platform_device.h>

 #include <asm/blackfin.h>
 #include <asm/irq.h>

 #define POLL_TIMEOUT       (2 * HZ)

 /* SMBus mode*/
 #define TWI_I2C_MODE_STANDARD		0x01
 #define TWI_I2C_MODE_STANDARDSUB	0x02
 #define TWI_I2C_MODE_COMBINED		0x04

 struct bfin_twi_iface {
 	int			irq;
 	spinlock_t		lock;
 	char			read_write;
 	u8			command;
 	u8			*transPtr;
 	int			readNum;
 	int			writeNum;
 	int			cur_mode;
 	int			manual_stop;
 	int			result;
 	int			timeout_count;
 	struct timer_list	timeout_timer;
 	struct i2c_adapter	adap;
 	struct completion	complete;
 };

 static struct bfin_twi_iface twi_iface;

 static void bfin_twi_handle_interrupt(struct bfin_twi_iface *iface)
 {
 	unsigned short twi_int_status = bfin_read_TWI_INT_STAT();
 	unsigned short mast_stat = bfin_read_TWI_MASTER_STAT();

 	if (twi_int_status & XMTSERV) {
 		/* Transmit next data */
 		if (iface->writeNum > 0) {
 			bfin_write_TWI_XMT_DATA8(*(iface->transPtr++));
 			iface->writeNum--;
 		}
 		/* start receive immediately after complete sending in
 		 * combine mode.
 		 */
 		else if (iface->cur_mode == TWI_I2C_MODE_COMBINED) {
 			bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL()
 				| MDIR | RSTART);
 		} else if (iface->manual_stop)
 			bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL()
 				| STOP);
 		SSYNC();
 		/* Clear status */
 		bfin_write_TWI_INT_STAT(XMTSERV);
 		SSYNC();
 	}
 	if (twi_int_status & RCVSERV) {
 		if (iface->readNum > 0) {
 			/* Receive next data */
 			*(iface->transPtr) = bfin_read_TWI_RCV_DATA8();
 			if (iface->cur_mode == TWI_I2C_MODE_COMBINED) {
 				/* Change combine mode into sub mode after
 				 * read first data.
 				 */
 				iface->cur_mode = TWI_I2C_MODE_STANDARDSUB;
 				/* Get read number from first byte in block
 				 * combine mode.
 				 */
 				if (iface->readNum == 1 && iface->manual_stop)
 					iface->readNum = *iface->transPtr + 1;
 			}
 			iface->transPtr++;
 			iface->readNum--;
 		} else if (iface->manual_stop) {
 			bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL()
 				| STOP);
 			SSYNC();
 		}
 		/* Clear interrupt source */
 		bfin_write_TWI_INT_STAT(RCVSERV);
 		SSYNC();
 	}
 	if (twi_int_status & MERR) {
 		bfin_write_TWI_INT_STAT(MERR);
 		bfin_write_TWI_INT_MASK(0);
 		bfin_write_TWI_MASTER_STAT(0x3e);
 		bfin_write_TWI_MASTER_CTL(0);
 		SSYNC();
 		iface->result = -1;
 		/* if both err and complete int stats are set, return proper
 		 * results.
 		 */
 		if (twi_int_status & MCOMP) {
 			bfin_write_TWI_INT_STAT(MCOMP);
 			bfin_write_TWI_INT_MASK(0);
 			bfin_write_TWI_MASTER_CTL(0);
 			SSYNC();
 			/* If it is a quick transfer, only address bug no data,
 			 * not an err, return 1.
 			 */
 			if (iface->writeNum == 0 && (mast_stat & BUFRDERR))
 				iface->result = 1;
 			/* If address not acknowledged return -1,
 			 * else return 0.
 			 */
 			else if (!(mast_stat & ANAK))
 				iface->result = 0;
 		}
 		complete(&iface->complete);
 		return;
 	}
 	if (twi_int_status & MCOMP) {
 		bfin_write_TWI_INT_STAT(MCOMP);
 		SSYNC();
 		if (iface->cur_mode == TWI_I2C_MODE_COMBINED) {
 			if (iface->readNum == 0) {
 				/* set the read number to 1 and ask for manual
 				 * stop in block combine mode
 				 */
 				iface->readNum = 1;
 				iface->manual_stop = 1;
 				bfin_write_TWI_MASTER_CTL(
 					bfin_read_TWI_MASTER_CTL()
 					| (0xff << 6));
 			} else {
 				/* set the readd number in other
 				 * combine mode.
 				 */
 				bfin_write_TWI_MASTER_CTL(
 					(bfin_read_TWI_MASTER_CTL() &
 					(~(0xff << 6))) |
 					( iface->readNum << 6));
 			}
 			/* remove restart bit and enable master receive */
 			bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL() &
 				~RSTART);
 			bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL() |
 				MEN | MDIR);
 			SSYNC();
 		} else {
 			iface->result = 1;
 			bfin_write_TWI_INT_MASK(0);
 			bfin_write_TWI_MASTER_CTL(0);
 			SSYNC();
 			complete(&iface->complete);
 		}
 	}
 }

 /* Interrupt handler */
 static irqreturn_t bfin_twi_interrupt_entry(int irq, void *dev_id)
 {
 	struct bfin_twi_iface *iface = dev_id;
 	unsigned long flags;

 	spin_lock_irqsave(&iface->lock, flags);
 	del_timer(&iface->timeout_timer);
 	bfin_twi_handle_interrupt(iface);
 	spin_unlock_irqrestore(&iface->lock, flags);
 	return IRQ_HANDLED;
 }

 static void bfin_twi_timeout(unsigned long data)
 {
 	struct bfin_twi_iface *iface = (struct bfin_twi_iface *)data;
 	unsigned long flags;

 	spin_lock_irqsave(&iface->lock, flags);
 	bfin_twi_handle_interrupt(iface);
 	if (iface->result == 0) {
 		iface->timeout_count--;
 		if (iface->timeout_count > 0) {
 			iface->timeout_timer.expires = jiffies + POLL_TIMEOUT;
 			add_timer(&iface->timeout_timer);
 		} else {
 			iface->result = -1;
 			complete(&iface->complete);
 		}
 	}
 	spin_unlock_irqrestore(&iface->lock, flags);
 }

 /*
  * Generic i2c master transfer entrypoint
  */
 static int bfin_twi_master_xfer(struct i2c_adapter *adap,
 				struct i2c_msg *msgs, int num)
 {
 	struct bfin_twi_iface *iface = adap->algo_data;
 	struct i2c_msg *pmsg;
 	int i, ret;
 	int rc = 0;

 	if (!(bfin_read_TWI_CONTROL() & TWI_ENA))
 		return -ENXIO;

 	while (bfin_read_TWI_MASTER_STAT() & BUSBUSY) {
 		yield();
 	}

 	ret = 0;
 	for (i = 0; rc >= 0 && i < num; i++) {
 		pmsg = &msgs[i];
 		if (pmsg->flags & I2C_M_TEN) {
 			dev_err(&(adap->dev), "i2c-bfin-twi: 10 bits addr "
 				"not supported !\n");
 			rc = -EINVAL;
 			break;
 		}

 		iface->cur_mode = TWI_I2C_MODE_STANDARD;
 		iface->manual_stop = 0;
 		iface->transPtr = pmsg->buf;
 		iface->writeNum = iface->readNum = pmsg->len;
 		iface->result = 0;
 		iface->timeout_count = 10;
 		/* Set Transmit device address */
 		bfin_write_TWI_MASTER_ADDR(pmsg->addr);

 		/* FIFO Initiation. Data in FIFO should be
 		 *  discarded before start a new operation.
 		 */
 		bfin_write_TWI_FIFO_CTL(0x3);
 		SSYNC();
 		bfin_write_TWI_FIFO_CTL(0);
 		SSYNC();

 		if (pmsg->flags & I2C_M_RD)
 			iface->read_write = I2C_SMBUS_READ;
 		else {
 			iface->read_write = I2C_SMBUS_WRITE;
 			/* Transmit first data */
 			if (iface->writeNum > 0) {
 				bfin_write_TWI_XMT_DATA8(*(iface->transPtr++));
 				iface->writeNum--;
 				SSYNC();
 			}
 		}

 		/* clear int stat */
 		bfin_write_TWI_INT_STAT(MERR|MCOMP|XMTSERV|RCVSERV);

 		/* Interrupt mask . Enable XMT, RCV interrupt */
 		bfin_write_TWI_INT_MASK(MCOMP | MERR |
 			((iface->read_write == I2C_SMBUS_READ)?
 			RCVSERV : XMTSERV));
 		SSYNC();

 		if (pmsg->len > 0 && pmsg->len <= 255)
 			bfin_write_TWI_MASTER_CTL(pmsg->len << 6);
 		else if (pmsg->len > 255) {
 			bfin_write_TWI_MASTER_CTL(0xff << 6);
 			iface->manual_stop = 1;
 		} else
 			break;

 		iface->timeout_timer.expires = jiffies + POLL_TIMEOUT;
 		add_timer(&iface->timeout_timer);

 		/* Master enable */
 		bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL() | MEN |
 			((iface->read_write == I2C_SMBUS_READ) ? MDIR : 0) |
 			((CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ>100) ? FAST : 0));
 		SSYNC();

 		wait_for_completion(&iface->complete);

 		rc = iface->result;
 		if (rc == 1)
 			ret++;
 		else if (rc == -1)
 			break;
 	}

 	return ret;
 }

 /*
  * SMBus type transfer entrypoint
  */

 int bfin_twi_smbus_xfer(struct i2c_adapter *adap, u16 addr,
 			unsigned short flags, char read_write,
 			u8 command, int size, union i2c_smbus_data *data)
 {
 	struct bfin_twi_iface *iface = adap->algo_data;
 	int rc = 0;

 	if (!(bfin_read_TWI_CONTROL() & TWI_ENA))
 		return -ENXIO;

 	while (bfin_read_TWI_MASTER_STAT() & BUSBUSY) {
 		yield();
 	}

 	iface->writeNum = 0;
 	iface->readNum = 0;

 	/* Prepare datas & select mode */
 	switch (size) {
 	case I2C_SMBUS_QUICK:
 		iface->transPtr = NULL;
 		iface->cur_mode = TWI_I2C_MODE_STANDARD;
 		break;
 	case I2C_SMBUS_BYTE:
 		if (data == NULL)
 			iface->transPtr = NULL;
 		else {
 			if (read_write == I2C_SMBUS_READ)
 				iface->readNum = 1;
 			else
 				iface->writeNum = 1;
 			iface->transPtr = &data->byte;
 		}
 		iface->cur_mode = TWI_I2C_MODE_STANDARD;
 		break;
 	case I2C_SMBUS_BYTE_DATA:
 		if (read_write == I2C_SMBUS_READ) {
 			iface->readNum = 1;
 			iface->cur_mode = TWI_I2C_MODE_COMBINED;
 		} else {
 			iface->writeNum = 1;
 			iface->cur_mode = TWI_I2C_MODE_STANDARDSUB;
 		}
 		iface->transPtr = &data->byte;
 		break;
 	case I2C_SMBUS_WORD_DATA:
 		if (read_write == I2C_SMBUS_READ) {
 			iface->readNum = 2;
 			iface->cur_mode = TWI_I2C_MODE_COMBINED;
 		} else {
 			iface->writeNum = 2;
 			iface->cur_mode = TWI_I2C_MODE_STANDARDSUB;
 		}
 		iface->transPtr = (u8 *)&data->word;
 		break;
 	case I2C_SMBUS_PROC_CALL:
 		iface->writeNum = 2;
 		iface->readNum = 2;
 		iface->cur_mode = TWI_I2C_MODE_COMBINED;
 		iface->transPtr = (u8 *)&data->word;
 		break;
 	case I2C_SMBUS_BLOCK_DATA:
 		if (read_write == I2C_SMBUS_READ) {
 			iface->readNum = 0;
 			iface->cur_mode = TWI_I2C_MODE_COMBINED;
 		} else {
 			iface->writeNum = data->block[0] + 1;
 			iface->cur_mode = TWI_I2C_MODE_STANDARDSUB;
 		}
 		iface->transPtr = data->block;
 		break;
 	default:
 		return -1;
 	}

 	iface->result = 0;
 	iface->manual_stop = 0;
 	iface->read_write = read_write;
 	iface->command = command;
 	iface->timeout_count = 10;

 	/* FIFO Initiation. Data in FIFO should be discarded before
 	 * start a new operation.
 	 */
 	bfin_write_TWI_FIFO_CTL(0x3);
 	SSYNC();
 	bfin_write_TWI_FIFO_CTL(0);

 	/* clear int stat */
 	bfin_write_TWI_INT_STAT(MERR|MCOMP|XMTSERV|RCVSERV);

 	/* Set Transmit device address */
 	bfin_write_TWI_MASTER_ADDR(addr);
 	SSYNC();

 	iface->timeout_timer.expires = jiffies + POLL_TIMEOUT;
 	add_timer(&iface->timeout_timer);

 	switch (iface->cur_mode) {
 	case TWI_I2C_MODE_STANDARDSUB:
 		bfin_write_TWI_XMT_DATA8(iface->command);
 		bfin_write_TWI_INT_MASK(MCOMP | MERR |
 			((iface->read_write == I2C_SMBUS_READ) ?
 			RCVSERV : XMTSERV));
 		SSYNC();

 		if (iface->writeNum + 1 <= 255)
 			bfin_write_TWI_MASTER_CTL((iface->writeNum + 1) << 6);
 		else {
 			bfin_write_TWI_MASTER_CTL(0xff << 6);
 			iface->manual_stop = 1;
 		}
 		/* Master enable */
 		bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL() | MEN |
 			((CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ>100) ? FAST : 0));
 		break;
 	case TWI_I2C_MODE_COMBINED:
 		bfin_write_TWI_XMT_DATA8(iface->command);
 		bfin_write_TWI_INT_MASK(MCOMP | MERR | RCVSERV | XMTSERV);
 		SSYNC();

 		if (iface->writeNum > 0)
 			bfin_write_TWI_MASTER_CTL((iface->writeNum + 1) << 6);
 		else
 			bfin_write_TWI_MASTER_CTL(0x1 << 6);
 		/* Master enable */
 		bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL() | MEN |
 			((CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ>100) ? FAST : 0));
 		break;
 	default:
 		bfin_write_TWI_MASTER_CTL(0);
 		if (size != I2C_SMBUS_QUICK) {
 			/* Don't access xmit data register when this is a
 			 * read operation.
 			 */
 			if (iface->read_write != I2C_SMBUS_READ) {
 				if (iface->writeNum > 0) {
 					bfin_write_TWI_XMT_DATA8(*(iface->transPtr++));
 					if (iface->writeNum <= 255)
 						bfin_write_TWI_MASTER_CTL(iface->writeNum << 6);
 					else {
 						bfin_write_TWI_MASTER_CTL(0xff << 6);
 						iface->manual_stop = 1;
 					}
 					iface->writeNum--;
 				} else {
 					bfin_write_TWI_XMT_DATA8(iface->command);
 					bfin_write_TWI_MASTER_CTL(1 << 6);
 				}
 			} else {
 				if (iface->readNum > 0 && iface->readNum <= 255)
 					bfin_write_TWI_MASTER_CTL(iface->readNum << 6);
 				else if (iface->readNum > 255) {
 					bfin_write_TWI_MASTER_CTL(0xff << 6);
 					iface->manual_stop = 1;
 				} else {
 					del_timer(&iface->timeout_timer);
 					break;
 				}
 			}
 		}
 		bfin_write_TWI_INT_MASK(MCOMP | MERR |
 			((iface->read_write == I2C_SMBUS_READ) ?
 			RCVSERV : XMTSERV));
 		SSYNC();

 		/* Master enable */
 		bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL() | MEN |
 			((iface->read_write == I2C_SMBUS_READ) ? MDIR : 0) |
 			((CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ > 100) ? FAST : 0));
 		break;
 	}
 	SSYNC();

 	wait_for_completion(&iface->complete);

 	rc = (iface->result >= 0) ? 0 : -1;

 	return rc;
 }

 /*
  * Return what the adapter supports
  */
 static u32 bfin_twi_functionality(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
 	       I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
 	       I2C_FUNC_SMBUS_BLOCK_DATA | I2C_FUNC_SMBUS_PROC_CALL |
 	       I2C_FUNC_I2C;
 }


 static struct i2c_algorithm bfin_twi_algorithm = {
 	.master_xfer   = bfin_twi_master_xfer,
 	.smbus_xfer    = bfin_twi_smbus_xfer,
 	.functionality = bfin_twi_functionality,
 };


 static int i2c_bfin_twi_suspend(struct platform_device *dev, pm_message_t state)
 {
 /*	struct bfin_twi_iface *iface = platform_get_drvdata(dev);*/

 	/* Disable TWI */
 	bfin_write_TWI_CONTROL(bfin_read_TWI_CONTROL() & ~TWI_ENA);
 	SSYNC();

 	return 0;
 }

 static int i2c_bfin_twi_resume(struct platform_device *dev)
 {
 /*	struct bfin_twi_iface *iface = platform_get_drvdata(dev);*/

 	/* Enable TWI */
 	bfin_write_TWI_CONTROL(bfin_read_TWI_CONTROL() | TWI_ENA);
 	SSYNC();

 	return 0;
 }

 static int i2c_bfin_twi_probe(struct platform_device *dev)
 {
 	struct bfin_twi_iface *iface = &twi_iface;
 	struct i2c_adapter *p_adap;
 	int rc;

 	spin_lock_init(&(iface->lock));
 	init_completion(&(iface->complete));
 	iface->irq = IRQ_TWI;

 	init_timer(&(iface->timeout_timer));
 	iface->timeout_timer.function = bfin_twi_timeout;
 	iface->timeout_timer.data = (unsigned long)iface;

 	p_adap = &iface->adap;
 	p_adap->id = I2C_HW_BLACKFIN;
 	p_adap->nr = dev->id;
 	strlcpy(p_adap->name, dev->name, sizeof(p_adap->name));
 	p_adap->algo = &bfin_twi_algorithm;
 	p_adap->algo_data = iface;
 	p_adap->class = I2C_CLASS_ALL;
 	p_adap->dev.parent = &dev->dev;

 	rc = request_irq(iface->irq, bfin_twi_interrupt_entry,
 		IRQF_DISABLED, dev->name, iface);
 	if (rc) {
 		dev_err(&(p_adap->dev), "i2c-bfin-twi: can't get IRQ %d !\n",
 			iface->irq);
 		return -ENODEV;
 	}

 	/* Set TWI internal clock as 10MHz */
 	bfin_write_TWI_CONTROL(((get_sclk() / 1024 / 1024 + 5) / 10) & 0x7F);

 	/* Set Twi interface clock as specified */
 	bfin_write_TWI_CLKDIV((( 5*1024 / CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ )
 			<< 8) | (( 5*1024 / CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ )
 			& 0xFF));

 	/* Enable TWI */
 	bfin_write_TWI_CONTROL(bfin_read_TWI_CONTROL() | TWI_ENA);
 	SSYNC();

 	rc = i2c_add_numbered_adapter(p_adap);
 	if (rc < 0)
 		free_irq(iface->irq, iface);
 	else
 		platform_set_drvdata(dev, iface);

 	return rc;
 }

 static int i2c_bfin_twi_remove(struct platform_device *pdev)
 {
 	struct bfin_twi_iface *iface = platform_get_drvdata(pdev);

 	platform_set_drvdata(pdev, NULL);

 	i2c_del_adapter(&(iface->adap));
 	free_irq(iface->irq, iface);

 	return 0;
 }

 static struct platform_driver i2c_bfin_twi_driver = {
 	.probe		= i2c_bfin_twi_probe,
 	.remove		= i2c_bfin_twi_remove,
 	.suspend	= i2c_bfin_twi_suspend,
 	.resume		= i2c_bfin_twi_resume,
 	.driver		= {
 		.name	= "i2c-bfin-twi",
 		.owner	= THIS_MODULE,
 	},
 };

 static int __init i2c_bfin_twi_init(void)
 {
 	pr_info("I2C: Blackfin I2C TWI driver\n");

 	return platform_driver_register(&i2c_bfin_twi_driver);
 }

 static void __exit i2c_bfin_twi_exit(void)
 {
 	platform_driver_unregister(&i2c_bfin_twi_driver);
 }

 MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
 MODULE_DESCRIPTION("I2C-Bus adapter routines for Blackfin TWI");
 MODULE_LICENSE("GPL");

 module_init(i2c_bfin_twi_init);
 module_exit(i2c_bfin_twi_exit);
	/*
	* drivers/i2c/busses/i2c-bfin-twi.c
	*
	* Description: Driver for Blackfin Two Wire Interface
	*
	* Author: sonicz <sonic.zhang@analog.com>
	*
	* Copyright (c) 2005-2007 Analog Devices, Inc.
	*
	* 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.
	*
	* 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.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	*/

	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <linux/init.h>
	#include <linux/i2c.h>
	#include <linux/mm.h>
	#include <linux/timer.h>
	#include <linux/spinlock.h>
	#include <linux/completion.h>
	#include <linux/interrupt.h>
	#include <linux/platform_device.h>

	#include <asm/blackfin.h>
	#include <asm/irq.h>

	#define POLL_TIMEOUT (2 * HZ)

	/* SMBus mode*/
	#define TWI_I2C_MODE_STANDARD 0x01
	#define TWI_I2C_MODE_STANDARDSUB 0x02
	#define TWI_I2C_MODE_COMBINED 0x04

	struct bfin_twi_iface {
	int irq;
	spinlock_t lock;
	char read_write;
	u8 command;
	u8 *transPtr;
	int readNum;
	int writeNum;
	int cur_mode;
	int manual_stop;
	int result;
	int timeout_count;
	struct timer_list timeout_timer;
	struct i2c_adapter adap;
	struct completion complete;
	};

	static struct bfin_twi_iface twi_iface;

	static void bfin_twi_handle_interrupt(struct bfin_twi_iface *iface)
	{
	unsigned short twi_int_status = bfin_read_TWI_INT_STAT();
	unsigned short mast_stat = bfin_read_TWI_MASTER_STAT();

	if (twi_int_status & XMTSERV) {
	/* Transmit next data */
	if (iface->writeNum > 0) {
	bfin_write_TWI_XMT_DATA8(*(iface->transPtr++));
	iface->writeNum--;
	}
	/* start receive immediately after complete sending in
	* combine mode.
	*/
	else if (iface->cur_mode == TWI_I2C_MODE_COMBINED) {
	bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL()
	\| MDIR \| RSTART);
	} else if (iface->manual_stop)
	bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL()
	\| STOP);
	SSYNC();
	/* Clear status */
	bfin_write_TWI_INT_STAT(XMTSERV);
	SSYNC();
	}
	if (twi_int_status & RCVSERV) {
	if (iface->readNum > 0) {
	/* Receive next data */
	*(iface->transPtr) = bfin_read_TWI_RCV_DATA8();
	if (iface->cur_mode == TWI_I2C_MODE_COMBINED) {
	/* Change combine mode into sub mode after
	* read first data.
	*/
	iface->cur_mode = TWI_I2C_MODE_STANDARDSUB;
	/* Get read number from first byte in block
	* combine mode.
	*/
	if (iface->readNum == 1 && iface->manual_stop)
	iface->readNum = *iface->transPtr + 1;
	}
	iface->transPtr++;
	iface->readNum--;
	} else if (iface->manual_stop) {
	bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL()
	\| STOP);
	SSYNC();
	}
	/* Clear interrupt source */
	bfin_write_TWI_INT_STAT(RCVSERV);
	SSYNC();
	}
	if (twi_int_status & MERR) {
	bfin_write_TWI_INT_STAT(MERR);
	bfin_write_TWI_INT_MASK(0);
	bfin_write_TWI_MASTER_STAT(0x3e);
	bfin_write_TWI_MASTER_CTL(0);
	SSYNC();
	iface->result = -1;
	/* if both err and complete int stats are set, return proper
	* results.
	*/
	if (twi_int_status & MCOMP) {
	bfin_write_TWI_INT_STAT(MCOMP);
	bfin_write_TWI_INT_MASK(0);
	bfin_write_TWI_MASTER_CTL(0);
	SSYNC();
	/* If it is a quick transfer, only address bug no data,
	* not an err, return 1.
	*/
	if (iface->writeNum == 0 && (mast_stat & BUFRDERR))
	iface->result = 1;
	/* If address not acknowledged return -1,
	* else return 0.
	*/
	else if (!(mast_stat & ANAK))
	iface->result = 0;
	}
	complete(&iface->complete);
	return;
	}
	if (twi_int_status & MCOMP) {
	bfin_write_TWI_INT_STAT(MCOMP);
	SSYNC();
	if (iface->cur_mode == TWI_I2C_MODE_COMBINED) {
	if (iface->readNum == 0) {
	/* set the read number to 1 and ask for manual
	* stop in block combine mode
	*/
	iface->readNum = 1;
	iface->manual_stop = 1;
	bfin_write_TWI_MASTER_CTL(
	bfin_read_TWI_MASTER_CTL()
	\| (0xff << 6));
	} else {
	/* set the readd number in other
	* combine mode.
	*/
	bfin_write_TWI_MASTER_CTL(
	(bfin_read_TWI_MASTER_CTL() &
	(~(0xff << 6))) \|
	( iface->readNum << 6));
	}
	/* remove restart bit and enable master receive */
	bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL() &
	~RSTART);
	bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL() \|
	MEN \| MDIR);
	SSYNC();
	} else {
	iface->result = 1;
	bfin_write_TWI_INT_MASK(0);
	bfin_write_TWI_MASTER_CTL(0);
	SSYNC();
	complete(&iface->complete);
	}
	}
	}

	/* Interrupt handler */
	static irqreturn_t bfin_twi_interrupt_entry(int irq, void *dev_id)
	{
	struct bfin_twi_iface *iface = dev_id;
	unsigned long flags;

	spin_lock_irqsave(&iface->lock, flags);
	del_timer(&iface->timeout_timer);
	bfin_twi_handle_interrupt(iface);
	spin_unlock_irqrestore(&iface->lock, flags);
	return IRQ_HANDLED;
	}

	static void bfin_twi_timeout(unsigned long data)
	{
	struct bfin_twi_iface iface = (struct bfin_twi_iface )data;
	unsigned long flags;

	spin_lock_irqsave(&iface->lock, flags);
	bfin_twi_handle_interrupt(iface);
	if (iface->result == 0) {
	iface->timeout_count--;
	if (iface->timeout_count > 0) {
	iface->timeout_timer.expires = jiffies + POLL_TIMEOUT;
	add_timer(&iface->timeout_timer);
	} else {
	iface->result = -1;
	complete(&iface->complete);
	}
	}
	spin_unlock_irqrestore(&iface->lock, flags);
	}

	/*
	* Generic i2c master transfer entrypoint
	*/
	static int bfin_twi_master_xfer(struct i2c_adapter *adap,
	struct i2c_msg *msgs, int num)
	{
	struct bfin_twi_iface *iface = adap->algo_data;
	struct i2c_msg *pmsg;
	int i, ret;
	int rc = 0;

	if (!(bfin_read_TWI_CONTROL() & TWI_ENA))
	return -ENXIO;

	while (bfin_read_TWI_MASTER_STAT() & BUSBUSY) {
	yield();
	}

	ret = 0;
	for (i = 0; rc >= 0 && i < num; i++) {
	pmsg = &msgs[i];
	if (pmsg->flags & I2C_M_TEN) {
	dev_err(&(adap->dev), "i2c-bfin-twi: 10 bits addr "
	"not supported !\n");
	rc = -EINVAL;
	break;
	}

	iface->cur_mode = TWI_I2C_MODE_STANDARD;
	iface->manual_stop = 0;
	iface->transPtr = pmsg->buf;
	iface->writeNum = iface->readNum = pmsg->len;
	iface->result = 0;
	iface->timeout_count = 10;
	/* Set Transmit device address */
	bfin_write_TWI_MASTER_ADDR(pmsg->addr);

	/* FIFO Initiation. Data in FIFO should be
	* discarded before start a new operation.
	*/
	bfin_write_TWI_FIFO_CTL(0x3);
	SSYNC();
	bfin_write_TWI_FIFO_CTL(0);
	SSYNC();

	if (pmsg->flags & I2C_M_RD)
	iface->read_write = I2C_SMBUS_READ;
	else {
	iface->read_write = I2C_SMBUS_WRITE;
	/* Transmit first data */
	if (iface->writeNum > 0) {
	bfin_write_TWI_XMT_DATA8(*(iface->transPtr++));
	iface->writeNum--;
	SSYNC();
	}
	}

	/* clear int stat */
	bfin_write_TWI_INT_STAT(MERR\|MCOMP\|XMTSERV\|RCVSERV);

	/* Interrupt mask . Enable XMT, RCV interrupt */
	bfin_write_TWI_INT_MASK(MCOMP \| MERR \|
	((iface->read_write == I2C_SMBUS_READ)?
	RCVSERV : XMTSERV));
	SSYNC();

	if (pmsg->len > 0 && pmsg->len <= 255)
	bfin_write_TWI_MASTER_CTL(pmsg->len << 6);
	else if (pmsg->len > 255) {
	bfin_write_TWI_MASTER_CTL(0xff << 6);
	iface->manual_stop = 1;
	} else
	break;

	iface->timeout_timer.expires = jiffies + POLL_TIMEOUT;
	add_timer(&iface->timeout_timer);

	/* Master enable */
	bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL() \| MEN \|
	((iface->read_write == I2C_SMBUS_READ) ? MDIR : 0) \|
	((CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ>100) ? FAST : 0));
	SSYNC();

	wait_for_completion(&iface->complete);

	rc = iface->result;
	if (rc == 1)
	ret++;
	else if (rc == -1)
	break;
	}

	return ret;
	}

	/*
	* SMBus type transfer entrypoint
	*/

	int bfin_twi_smbus_xfer(struct i2c_adapter *adap, u16 addr,
	unsigned short flags, char read_write,
	u8 command, int size, union i2c_smbus_data *data)
	{
	struct bfin_twi_iface *iface = adap->algo_data;
	int rc = 0;

	if (!(bfin_read_TWI_CONTROL() & TWI_ENA))
	return -ENXIO;

	while (bfin_read_TWI_MASTER_STAT() & BUSBUSY) {
	yield();
	}

	iface->writeNum = 0;
	iface->readNum = 0;

	/* Prepare datas & select mode */
	switch (size) {
	case I2C_SMBUS_QUICK:
	iface->transPtr = NULL;
	iface->cur_mode = TWI_I2C_MODE_STANDARD;
	break;
	case I2C_SMBUS_BYTE:
	if (data == NULL)
	iface->transPtr = NULL;
	else {
	if (read_write == I2C_SMBUS_READ)
	iface->readNum = 1;
	else
	iface->writeNum = 1;
	iface->transPtr = &data->byte;
	}
	iface->cur_mode = TWI_I2C_MODE_STANDARD;
	break;
	case I2C_SMBUS_BYTE_DATA:
	if (read_write == I2C_SMBUS_READ) {
	iface->readNum = 1;
	iface->cur_mode = TWI_I2C_MODE_COMBINED;
	} else {
	iface->writeNum = 1;
	iface->cur_mode = TWI_I2C_MODE_STANDARDSUB;
	}
	iface->transPtr = &data->byte;
	break;
	case I2C_SMBUS_WORD_DATA:
	if (read_write == I2C_SMBUS_READ) {
	iface->readNum = 2;
	iface->cur_mode = TWI_I2C_MODE_COMBINED;
	} else {
	iface->writeNum = 2;
	iface->cur_mode = TWI_I2C_MODE_STANDARDSUB;
	}
	iface->transPtr = (u8 *)&data->word;
	break;
	case I2C_SMBUS_PROC_CALL:
	iface->writeNum = 2;
	iface->readNum = 2;
	iface->cur_mode = TWI_I2C_MODE_COMBINED;
	iface->transPtr = (u8 *)&data->word;
	break;
	case I2C_SMBUS_BLOCK_DATA:
	if (read_write == I2C_SMBUS_READ) {
	iface->readNum = 0;
	iface->cur_mode = TWI_I2C_MODE_COMBINED;
	} else {
	iface->writeNum = data->block[0] + 1;
	iface->cur_mode = TWI_I2C_MODE_STANDARDSUB;
	}
	iface->transPtr = data->block;
	break;
	default:
	return -1;
	}

	iface->result = 0;
	iface->manual_stop = 0;
	iface->read_write = read_write;
	iface->command = command;
	iface->timeout_count = 10;

	/* FIFO Initiation. Data in FIFO should be discarded before
	* start a new operation.
	*/
	bfin_write_TWI_FIFO_CTL(0x3);
	SSYNC();
	bfin_write_TWI_FIFO_CTL(0);

	/* clear int stat */
	bfin_write_TWI_INT_STAT(MERR\|MCOMP\|XMTSERV\|RCVSERV);

	/* Set Transmit device address */
	bfin_write_TWI_MASTER_ADDR(addr);
	SSYNC();

	iface->timeout_timer.expires = jiffies + POLL_TIMEOUT;
	add_timer(&iface->timeout_timer);

	switch (iface->cur_mode) {
	case TWI_I2C_MODE_STANDARDSUB:
	bfin_write_TWI_XMT_DATA8(iface->command);
	bfin_write_TWI_INT_MASK(MCOMP \| MERR \|
	((iface->read_write == I2C_SMBUS_READ) ?
	RCVSERV : XMTSERV));
	SSYNC();

	if (iface->writeNum + 1 <= 255)
	bfin_write_TWI_MASTER_CTL((iface->writeNum + 1) << 6);
	else {
	bfin_write_TWI_MASTER_CTL(0xff << 6);
	iface->manual_stop = 1;
	}
	/* Master enable */
	bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL() \| MEN \|
	((CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ>100) ? FAST : 0));
	break;
	case TWI_I2C_MODE_COMBINED:
	bfin_write_TWI_XMT_DATA8(iface->command);
	bfin_write_TWI_INT_MASK(MCOMP \| MERR \| RCVSERV \| XMTSERV);
	SSYNC();

	if (iface->writeNum > 0)
	bfin_write_TWI_MASTER_CTL((iface->writeNum + 1) << 6);
	else
	bfin_write_TWI_MASTER_CTL(0x1 << 6);
	/* Master enable */
	bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL() \| MEN \|
	((CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ>100) ? FAST : 0));
	break;
	default:
	bfin_write_TWI_MASTER_CTL(0);
	if (size != I2C_SMBUS_QUICK) {
	/* Don't access xmit data register when this is a
	* read operation.
	*/
	if (iface->read_write != I2C_SMBUS_READ) {
	if (iface->writeNum > 0) {
	bfin_write_TWI_XMT_DATA8(*(iface->transPtr++));
	if (iface->writeNum <= 255)
	bfin_write_TWI_MASTER_CTL(iface->writeNum << 6);
	else {
	bfin_write_TWI_MASTER_CTL(0xff << 6);
	iface->manual_stop = 1;
	}
	iface->writeNum--;
	} else {
	bfin_write_TWI_XMT_DATA8(iface->command);
	bfin_write_TWI_MASTER_CTL(1 << 6);
	}
	} else {
	if (iface->readNum > 0 && iface->readNum <= 255)
	bfin_write_TWI_MASTER_CTL(iface->readNum << 6);
	else if (iface->readNum > 255) {
	bfin_write_TWI_MASTER_CTL(0xff << 6);
	iface->manual_stop = 1;
	} else {
	del_timer(&iface->timeout_timer);
	break;
	}
	}
	}
	bfin_write_TWI_INT_MASK(MCOMP \| MERR \|
	((iface->read_write == I2C_SMBUS_READ) ?
	RCVSERV : XMTSERV));
	SSYNC();

	/* Master enable */
	bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL() \| MEN \|
	((iface->read_write == I2C_SMBUS_READ) ? MDIR : 0) \|
	((CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ > 100) ? FAST : 0));
	break;
	}
	SSYNC();

	wait_for_completion(&iface->complete);

	rc = (iface->result >= 0) ? 0 : -1;

	return rc;
	}

	/*
	* Return what the adapter supports
	*/
	static u32 bfin_twi_functionality(struct i2c_adapter *adap)
	{
	return I2C_FUNC_SMBUS_QUICK \| I2C_FUNC_SMBUS_BYTE \|
	I2C_FUNC_SMBUS_BYTE_DATA \| I2C_FUNC_SMBUS_WORD_DATA \|
	I2C_FUNC_SMBUS_BLOCK_DATA \| I2C_FUNC_SMBUS_PROC_CALL \|
	I2C_FUNC_I2C;
	}


	static struct i2c_algorithm bfin_twi_algorithm = {
	.master_xfer = bfin_twi_master_xfer,
	.smbus_xfer = bfin_twi_smbus_xfer,
	.functionality = bfin_twi_functionality,
	};


	static int i2c_bfin_twi_suspend(struct platform_device *dev, pm_message_t state)
	{
	/* struct bfin_twi_iface iface = platform_get_drvdata(dev);/

	/* Disable TWI */
	bfin_write_TWI_CONTROL(bfin_read_TWI_CONTROL() & ~TWI_ENA);
	SSYNC();

	return 0;
	}

	static int i2c_bfin_twi_resume(struct platform_device *dev)
	{
	/* struct bfin_twi_iface iface = platform_get_drvdata(dev);/

	/* Enable TWI */
	bfin_write_TWI_CONTROL(bfin_read_TWI_CONTROL() \| TWI_ENA);
	SSYNC();

	return 0;
	}

	static int i2c_bfin_twi_probe(struct platform_device *dev)
	{
	struct bfin_twi_iface *iface = &twi_iface;
	struct i2c_adapter *p_adap;
	int rc;

	spin_lock_init(&(iface->lock));
	init_completion(&(iface->complete));
	iface->irq = IRQ_TWI;

	init_timer(&(iface->timeout_timer));
	iface->timeout_timer.function = bfin_twi_timeout;
	iface->timeout_timer.data = (unsigned long)iface;

	p_adap = &iface->adap;
	p_adap->id = I2C_HW_BLACKFIN;
	p_adap->nr = dev->id;
	strlcpy(p_adap->name, dev->name, sizeof(p_adap->name));
	p_adap->algo = &bfin_twi_algorithm;
	p_adap->algo_data = iface;
	p_adap->class = I2C_CLASS_ALL;
	p_adap->dev.parent = &dev->dev;

	rc = request_irq(iface->irq, bfin_twi_interrupt_entry,
	IRQF_DISABLED, dev->name, iface);
	if (rc) {
	dev_err(&(p_adap->dev), "i2c-bfin-twi: can't get IRQ %d !\n",
	iface->irq);
	return -ENODEV;
	}

	/* Set TWI internal clock as 10MHz */
	bfin_write_TWI_CONTROL(((get_sclk() / 1024 / 1024 + 5) / 10) & 0x7F);

	/* Set Twi interface clock as specified */
	bfin_write_TWI_CLKDIV((( 5*1024 / CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ )
	<< 8) \| (( 5*1024 / CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ )
	& 0xFF));

	/* Enable TWI */
	bfin_write_TWI_CONTROL(bfin_read_TWI_CONTROL() \| TWI_ENA);
	SSYNC();

	rc = i2c_add_numbered_adapter(p_adap);
	if (rc < 0)
	free_irq(iface->irq, iface);
	else
	platform_set_drvdata(dev, iface);

	return rc;
	}

	static int i2c_bfin_twi_remove(struct platform_device *pdev)
	{
	struct bfin_twi_iface *iface = platform_get_drvdata(pdev);

	platform_set_drvdata(pdev, NULL);

	i2c_del_adapter(&(iface->adap));
	free_irq(iface->irq, iface);

	return 0;
	}

	static struct platform_driver i2c_bfin_twi_driver = {
	.probe = i2c_bfin_twi_probe,
	.remove = i2c_bfin_twi_remove,
	.suspend = i2c_bfin_twi_suspend,
	.resume = i2c_bfin_twi_resume,
	.driver = {
	.name = "i2c-bfin-twi",
	.owner = THIS_MODULE,
	},
	};

	static int __init i2c_bfin_twi_init(void)
	{
	pr_info("I2C: Blackfin I2C TWI driver\n");

	return platform_driver_register(&i2c_bfin_twi_driver);
	}

	static void __exit i2c_bfin_twi_exit(void)
	{
	platform_driver_unregister(&i2c_bfin_twi_driver);
	}

	MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
	MODULE_DESCRIPTION("I2C-Bus adapter routines for Blackfin TWI");
	MODULE_LICENSE("GPL");

	module_init(i2c_bfin_twi_init);
	module_exit(i2c_bfin_twi_exit);