drivers/i2c/busses/i2c-designware-common.c - linux/kernel/git/torvalds/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Synopsys DesignWare I2C adapter driver.
  *
  * Based on the TI DAVINCI I2C adapter driver.
  *
  * Copyright (C) 2006 Texas Instruments.
  * Copyright (C) 2007 MontaVista Software Inc.
  * Copyright (C) 2009 Provigent Ltd.
  */
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/export.h>
 #include <linux/errno.h>
 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/pm_runtime.h>
 #include <linux/swab.h>

 #include "i2c-designware-core.h"

 static char *abort_sources[] = {
 	[ABRT_7B_ADDR_NOACK] =
 		"slave address not acknowledged (7bit mode)",
 	[ABRT_10ADDR1_NOACK] =
 		"first address byte not acknowledged (10bit mode)",
 	[ABRT_10ADDR2_NOACK] =
 		"second address byte not acknowledged (10bit mode)",
 	[ABRT_TXDATA_NOACK] =
 		"data not acknowledged",
 	[ABRT_GCALL_NOACK] =
 		"no acknowledgement for a general call",
 	[ABRT_GCALL_READ] =
 		"read after general call",
 	[ABRT_SBYTE_ACKDET] =
 		"start byte acknowledged",
 	[ABRT_SBYTE_NORSTRT] =
 		"trying to send start byte when restart is disabled",
 	[ABRT_10B_RD_NORSTRT] =
 		"trying to read when restart is disabled (10bit mode)",
 	[ABRT_MASTER_DIS] =
 		"trying to use disabled adapter",
 	[ARB_LOST] =
 		"lost arbitration",
 	[ABRT_SLAVE_FLUSH_TXFIFO] =
 		"read command so flush old data in the TX FIFO",
 	[ABRT_SLAVE_ARBLOST] =
 		"slave lost the bus while transmitting data to a remote master",
 	[ABRT_SLAVE_RD_INTX] =
 		"incorrect slave-transmitter mode configuration",
 };

 u32 dw_readl(struct dw_i2c_dev *dev, int offset)
 {
 	u32 value;

 	if (dev->flags & ACCESS_16BIT)
 		value = readw_relaxed(dev->base + offset) |
 			(readw_relaxed(dev->base + offset + 2) << 16);
 	else
 		value = readl_relaxed(dev->base + offset);

 	if (dev->flags & ACCESS_SWAP)
 		return swab32(value);
 	else
 		return value;
 }

 void dw_writel(struct dw_i2c_dev *dev, u32 b, int offset)
 {
 	if (dev->flags & ACCESS_SWAP)
 		b = swab32(b);

 	if (dev->flags & ACCESS_16BIT) {
 		writew_relaxed((u16)b, dev->base + offset);
 		writew_relaxed((u16)(b >> 16), dev->base + offset + 2);
 	} else {
 		writel_relaxed(b, dev->base + offset);
 	}
 }

 /**
  * i2c_dw_set_reg_access() - Set register access flags
  * @dev: device private data
  *
  * Autodetects needed register access mode and sets access flags accordingly.
  * This must be called before doing any other register access.
  */
 int i2c_dw_set_reg_access(struct dw_i2c_dev *dev)
 {
 	u32 reg;
 	int ret;

 	ret = i2c_dw_acquire_lock(dev);
 	if (ret)
 		return ret;

 	reg = dw_readl(dev, DW_IC_COMP_TYPE);
 	i2c_dw_release_lock(dev);

 	if (reg == swab32(DW_IC_COMP_TYPE_VALUE)) {
 		/* Configure register endianess access */
 		dev->flags |= ACCESS_SWAP;
 	} else if (reg == (DW_IC_COMP_TYPE_VALUE & 0x0000ffff)) {
 		/* Configure register access mode 16bit */
 		dev->flags |= ACCESS_16BIT;
 	} else if (reg != DW_IC_COMP_TYPE_VALUE) {
 		dev_err(dev->dev,
 			"Unknown Synopsys component type: 0x%08x\n", reg);
 		return -ENODEV;
 	}

 	return 0;
 }

 u32 i2c_dw_scl_hcnt(u32 ic_clk, u32 tSYMBOL, u32 tf, int cond, int offset)
 {
 	/*
 	 * DesignWare I2C core doesn't seem to have solid strategy to meet
 	 * the tHD;STA timing spec.  Configuring _HCNT based on tHIGH spec
 	 * will result in violation of the tHD;STA spec.
 	 */
 	if (cond)
 		/*
 		 * Conditional expression:
 		 *
 		 *   IC_[FS]S_SCL_HCNT + (1+4+3) >= IC_CLK * tHIGH
 		 *
 		 * This is based on the DW manuals, and represents an ideal
 		 * configuration.  The resulting I2C bus speed will be
 		 * faster than any of the others.
 		 *
 		 * If your hardware is free from tHD;STA issue, try this one.
 		 */
 		return (ic_clk * tSYMBOL + 500000) / 1000000 - 8 + offset;
 	else
 		/*
 		 * Conditional expression:
 		 *
 		 *   IC_[FS]S_SCL_HCNT + 3 >= IC_CLK * (tHD;STA + tf)
 		 *
 		 * This is just experimental rule; the tHD;STA period turned
 		 * out to be proportinal to (_HCNT + 3).  With this setting,
 		 * we could meet both tHIGH and tHD;STA timing specs.
 		 *
 		 * If unsure, you'd better to take this alternative.
 		 *
 		 * The reason why we need to take into account "tf" here,
 		 * is the same as described in i2c_dw_scl_lcnt().
 		 */
 		return (ic_clk * (tSYMBOL + tf) + 500000) / 1000000
 			- 3 + offset;
 }

 u32 i2c_dw_scl_lcnt(u32 ic_clk, u32 tLOW, u32 tf, int offset)
 {
 	/*
 	 * Conditional expression:
 	 *
 	 *   IC_[FS]S_SCL_LCNT + 1 >= IC_CLK * (tLOW + tf)
 	 *
 	 * DW I2C core starts counting the SCL CNTs for the LOW period
 	 * of the SCL clock (tLOW) as soon as it pulls the SCL line.
 	 * In order to meet the tLOW timing spec, we need to take into
 	 * account the fall time of SCL signal (tf).  Default tf value
 	 * should be 0.3 us, for safety.
 	 */
 	return ((ic_clk * (tLOW + tf) + 500000) / 1000000) - 1 + offset;
 }

 int i2c_dw_set_sda_hold(struct dw_i2c_dev *dev)
 {
 	u32 reg;
 	int ret;

 	ret = i2c_dw_acquire_lock(dev);
 	if (ret)
 		return ret;

 	/* Configure SDA Hold Time if required */
 	reg = dw_readl(dev, DW_IC_COMP_VERSION);
 	if (reg >= DW_IC_SDA_HOLD_MIN_VERS) {
 		if (!dev->sda_hold_time) {
 			/* Keep previous hold time setting if no one set it */
 			dev->sda_hold_time = dw_readl(dev, DW_IC_SDA_HOLD);
 		}

 		/*
 		 * Workaround for avoiding TX arbitration lost in case I2C
 		 * slave pulls SDA down "too quickly" after falling egde of
 		 * SCL by enabling non-zero SDA RX hold. Specification says it
 		 * extends incoming SDA low to high transition while SCL is
 		 * high but it apprears to help also above issue.
 		 */
 		if (!(dev->sda_hold_time & DW_IC_SDA_HOLD_RX_MASK))
 			dev->sda_hold_time |= 1 << DW_IC_SDA_HOLD_RX_SHIFT;

 		dev_dbg(dev->dev, "SDA Hold Time TX:RX = %d:%d\n",
 			dev->sda_hold_time & ~(u32)DW_IC_SDA_HOLD_RX_MASK,
 			dev->sda_hold_time >> DW_IC_SDA_HOLD_RX_SHIFT);
 	} else if (dev->set_sda_hold_time) {
 		dev->set_sda_hold_time(dev);
 	} else if (dev->sda_hold_time) {
 		dev_warn(dev->dev,
 			"Hardware too old to adjust SDA hold time.\n");
 		dev->sda_hold_time = 0;
 	}

 	i2c_dw_release_lock(dev);

 	return 0;
 }

 void __i2c_dw_disable(struct dw_i2c_dev *dev)
 {
 	int timeout = 100;

 	do {
 		__i2c_dw_disable_nowait(dev);
 		/*
 		 * The enable status register may be unimplemented, but
 		 * in that case this test reads zero and exits the loop.
 		 */
 		if ((dw_readl(dev, DW_IC_ENABLE_STATUS) & 1) == 0)
 			return;

 		/*
 		 * Wait 10 times the signaling period of the highest I2C
 		 * transfer supported by the driver (for 400KHz this is
 		 * 25us) as described in the DesignWare I2C databook.
 		 */
 		usleep_range(25, 250);
 	} while (timeout--);

 	dev_warn(dev->dev, "timeout in disabling adapter\n");
 }

 unsigned long i2c_dw_clk_rate(struct dw_i2c_dev *dev)
 {
 	/*
 	 * Clock is not necessary if we got LCNT/HCNT values directly from
 	 * the platform code.
 	 */
 	if (WARN_ON_ONCE(!dev->get_clk_rate_khz))
 		return 0;
 	return dev->get_clk_rate_khz(dev);
 }

 int i2c_dw_prepare_clk(struct dw_i2c_dev *dev, bool prepare)
 {
 	int ret;

 	if (IS_ERR(dev->clk))
 		return PTR_ERR(dev->clk);

 	if (prepare) {
 		/* Optional interface clock */
 		ret = clk_prepare_enable(dev->pclk);
 		if (ret)
 			return ret;

 		ret = clk_prepare_enable(dev->clk);
 		if (ret)
 			clk_disable_unprepare(dev->pclk);

 		return ret;
 	}

 	clk_disable_unprepare(dev->clk);
 	clk_disable_unprepare(dev->pclk);

 	return 0;
 }
 EXPORT_SYMBOL_GPL(i2c_dw_prepare_clk);

 int i2c_dw_acquire_lock(struct dw_i2c_dev *dev)
 {
 	int ret;

 	if (!dev->acquire_lock)
 		return 0;

 	ret = dev->acquire_lock();
 	if (!ret)
 		return 0;

 	dev_err(dev->dev, "couldn't acquire bus ownership\n");

 	return ret;
 }

 void i2c_dw_release_lock(struct dw_i2c_dev *dev)
 {
 	if (dev->release_lock)
 		dev->release_lock();
 }

 /*
  * Waiting for bus not busy
  */
 int i2c_dw_wait_bus_not_busy(struct dw_i2c_dev *dev)
 {
 	int timeout = TIMEOUT;

 	while (dw_readl(dev, DW_IC_STATUS) & DW_IC_STATUS_ACTIVITY) {
 		if (timeout <= 0) {
 			dev_warn(dev->dev, "timeout waiting for bus ready\n");
 			i2c_recover_bus(&dev->adapter);

 			if (dw_readl(dev, DW_IC_STATUS) & DW_IC_STATUS_ACTIVITY)
 				return -ETIMEDOUT;
 			return 0;
 		}
 		timeout--;
 		usleep_range(1000, 1100);
 	}

 	return 0;
 }

 int i2c_dw_handle_tx_abort(struct dw_i2c_dev *dev)
 {
 	unsigned long abort_source = dev->abort_source;
 	int i;

 	if (abort_source & DW_IC_TX_ABRT_NOACK) {
 		for_each_set_bit(i, &abort_source, ARRAY_SIZE(abort_sources))
 			dev_dbg(dev->dev,
 				"%s: %s\n", __func__, abort_sources[i]);
 		return -EREMOTEIO;
 	}

 	for_each_set_bit(i, &abort_source, ARRAY_SIZE(abort_sources))
 		dev_err(dev->dev, "%s: %s\n", __func__, abort_sources[i]);

 	if (abort_source & DW_IC_TX_ARB_LOST)
 		return -EAGAIN;
 	else if (abort_source & DW_IC_TX_ABRT_GCALL_READ)
 		return -EINVAL; /* wrong msgs[] data */
 	else
 		return -EIO;
 }

 u32 i2c_dw_func(struct i2c_adapter *adap)
 {
 	struct dw_i2c_dev *dev = i2c_get_adapdata(adap);

 	return dev->functionality;
 }

 void i2c_dw_disable(struct dw_i2c_dev *dev)
 {
 	/* Disable controller */
 	__i2c_dw_disable(dev);

 	/* Disable all interupts */
 	dw_writel(dev, 0, DW_IC_INTR_MASK);
 	dw_readl(dev, DW_IC_CLR_INTR);
 }

 void i2c_dw_disable_int(struct dw_i2c_dev *dev)
 {
 	dw_writel(dev, 0, DW_IC_INTR_MASK);
 }

 u32 i2c_dw_read_comp_param(struct dw_i2c_dev *dev)
 {
 	return dw_readl(dev, DW_IC_COMP_PARAM_1);
 }
 EXPORT_SYMBOL_GPL(i2c_dw_read_comp_param);

 MODULE_DESCRIPTION("Synopsys DesignWare I2C bus adapter core");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Synopsys DesignWare I2C adapter driver.
	*
	* Based on the TI DAVINCI I2C adapter driver.
	*
	* Copyright (C) 2006 Texas Instruments.
	* Copyright (C) 2007 MontaVista Software Inc.
	* Copyright (C) 2009 Provigent Ltd.
	*/
	#include <linux/clk.h>
	#include <linux/delay.h>
	#include <linux/export.h>
	#include <linux/errno.h>
	#include <linux/err.h>
	#include <linux/i2c.h>
	#include <linux/interrupt.h>
	#include <linux/io.h>
	#include <linux/module.h>
	#include <linux/pm_runtime.h>
	#include <linux/swab.h>

	#include "i2c-designware-core.h"

	static char *abort_sources[] = {
	[ABRT_7B_ADDR_NOACK] =
	"slave address not acknowledged (7bit mode)",
	[ABRT_10ADDR1_NOACK] =
	"first address byte not acknowledged (10bit mode)",
	[ABRT_10ADDR2_NOACK] =
	"second address byte not acknowledged (10bit mode)",
	[ABRT_TXDATA_NOACK] =
	"data not acknowledged",
	[ABRT_GCALL_NOACK] =
	"no acknowledgement for a general call",
	[ABRT_GCALL_READ] =
	"read after general call",
	[ABRT_SBYTE_ACKDET] =
	"start byte acknowledged",
	[ABRT_SBYTE_NORSTRT] =
	"trying to send start byte when restart is disabled",
	[ABRT_10B_RD_NORSTRT] =
	"trying to read when restart is disabled (10bit mode)",
	[ABRT_MASTER_DIS] =
	"trying to use disabled adapter",
	[ARB_LOST] =
	"lost arbitration",
	[ABRT_SLAVE_FLUSH_TXFIFO] =
	"read command so flush old data in the TX FIFO",
	[ABRT_SLAVE_ARBLOST] =
	"slave lost the bus while transmitting data to a remote master",
	[ABRT_SLAVE_RD_INTX] =
	"incorrect slave-transmitter mode configuration",
	};

	u32 dw_readl(struct dw_i2c_dev *dev, int offset)
	{
	u32 value;

	if (dev->flags & ACCESS_16BIT)
	value = readw_relaxed(dev->base + offset) \|
	(readw_relaxed(dev->base + offset + 2) << 16);
	else
	value = readl_relaxed(dev->base + offset);

	if (dev->flags & ACCESS_SWAP)
	return swab32(value);
	else
	return value;
	}

	void dw_writel(struct dw_i2c_dev *dev, u32 b, int offset)
	{
	if (dev->flags & ACCESS_SWAP)
	b = swab32(b);

	if (dev->flags & ACCESS_16BIT) {
	writew_relaxed((u16)b, dev->base + offset);
	writew_relaxed((u16)(b >> 16), dev->base + offset + 2);
	} else {
	writel_relaxed(b, dev->base + offset);
	}
	}

	/**
	* i2c_dw_set_reg_access() - Set register access flags
	* @dev: device private data
	*
	* Autodetects needed register access mode and sets access flags accordingly.
	* This must be called before doing any other register access.
	*/
	int i2c_dw_set_reg_access(struct dw_i2c_dev *dev)
	{
	u32 reg;
	int ret;

	ret = i2c_dw_acquire_lock(dev);
	if (ret)
	return ret;

	reg = dw_readl(dev, DW_IC_COMP_TYPE);
	i2c_dw_release_lock(dev);

	if (reg == swab32(DW_IC_COMP_TYPE_VALUE)) {
	/* Configure register endianess access */
	dev->flags \|= ACCESS_SWAP;
	} else if (reg == (DW_IC_COMP_TYPE_VALUE & 0x0000ffff)) {
	/* Configure register access mode 16bit */
	dev->flags \|= ACCESS_16BIT;
	} else if (reg != DW_IC_COMP_TYPE_VALUE) {
	dev_err(dev->dev,
	"Unknown Synopsys component type: 0x%08x\n", reg);
	return -ENODEV;
	}

	return 0;
	}

	u32 i2c_dw_scl_hcnt(u32 ic_clk, u32 tSYMBOL, u32 tf, int cond, int offset)
	{
	/*
	* DesignWare I2C core doesn't seem to have solid strategy to meet
	* the tHD;STA timing spec. Configuring _HCNT based on tHIGH spec
	* will result in violation of the tHD;STA spec.
	*/
	if (cond)
	/*
	* Conditional expression:
	*
	* IC_[FS]S_SCL_HCNT + (1+4+3) >= IC_CLK * tHIGH
	*
	* This is based on the DW manuals, and represents an ideal
	* configuration. The resulting I2C bus speed will be
	* faster than any of the others.
	*
	* If your hardware is free from tHD;STA issue, try this one.
	*/
	return (ic_clk * tSYMBOL + 500000) / 1000000 - 8 + offset;
	else
	/*
	* Conditional expression:
	*
	* IC_[FS]S_SCL_HCNT + 3 >= IC_CLK * (tHD;STA + tf)
	*
	* This is just experimental rule; the tHD;STA period turned
	* out to be proportinal to (_HCNT + 3). With this setting,
	* we could meet both tHIGH and tHD;STA timing specs.
	*
	* If unsure, you'd better to take this alternative.
	*
	* The reason why we need to take into account "tf" here,
	* is the same as described in i2c_dw_scl_lcnt().
	*/
	return (ic_clk * (tSYMBOL + tf) + 500000) / 1000000
	- 3 + offset;
	}

	u32 i2c_dw_scl_lcnt(u32 ic_clk, u32 tLOW, u32 tf, int offset)
	{
	/*
	* Conditional expression:
	*
	* IC_[FS]S_SCL_LCNT + 1 >= IC_CLK * (tLOW + tf)
	*
	* DW I2C core starts counting the SCL CNTs for the LOW period
	* of the SCL clock (tLOW) as soon as it pulls the SCL line.
	* In order to meet the tLOW timing spec, we need to take into
	* account the fall time of SCL signal (tf). Default tf value
	* should be 0.3 us, for safety.
	*/
	return ((ic_clk * (tLOW + tf) + 500000) / 1000000) - 1 + offset;
	}

	int i2c_dw_set_sda_hold(struct dw_i2c_dev *dev)
	{
	u32 reg;
	int ret;

	ret = i2c_dw_acquire_lock(dev);
	if (ret)
	return ret;

	/* Configure SDA Hold Time if required */
	reg = dw_readl(dev, DW_IC_COMP_VERSION);
	if (reg >= DW_IC_SDA_HOLD_MIN_VERS) {
	if (!dev->sda_hold_time) {
	/* Keep previous hold time setting if no one set it */
	dev->sda_hold_time = dw_readl(dev, DW_IC_SDA_HOLD);
	}

	/*
	* Workaround for avoiding TX arbitration lost in case I2C
	* slave pulls SDA down "too quickly" after falling egde of
	* SCL by enabling non-zero SDA RX hold. Specification says it
	* extends incoming SDA low to high transition while SCL is
	* high but it apprears to help also above issue.
	*/
	if (!(dev->sda_hold_time & DW_IC_SDA_HOLD_RX_MASK))
	dev->sda_hold_time \|= 1 << DW_IC_SDA_HOLD_RX_SHIFT;

	dev_dbg(dev->dev, "SDA Hold Time TX:RX = %d:%d\n",
	dev->sda_hold_time & ~(u32)DW_IC_SDA_HOLD_RX_MASK,
	dev->sda_hold_time >> DW_IC_SDA_HOLD_RX_SHIFT);
	} else if (dev->set_sda_hold_time) {
	dev->set_sda_hold_time(dev);
	} else if (dev->sda_hold_time) {
	dev_warn(dev->dev,
	"Hardware too old to adjust SDA hold time.\n");
	dev->sda_hold_time = 0;
	}

	i2c_dw_release_lock(dev);

	return 0;
	}

	void __i2c_dw_disable(struct dw_i2c_dev *dev)
	{
	int timeout = 100;

	do {
	__i2c_dw_disable_nowait(dev);
	/*
	* The enable status register may be unimplemented, but
	* in that case this test reads zero and exits the loop.
	*/
	if ((dw_readl(dev, DW_IC_ENABLE_STATUS) & 1) == 0)
	return;

	/*
	* Wait 10 times the signaling period of the highest I2C
	* transfer supported by the driver (for 400KHz this is
	* 25us) as described in the DesignWare I2C databook.
	*/
	usleep_range(25, 250);
	} while (timeout--);

	dev_warn(dev->dev, "timeout in disabling adapter\n");
	}

	unsigned long i2c_dw_clk_rate(struct dw_i2c_dev *dev)
	{
	/*
	* Clock is not necessary if we got LCNT/HCNT values directly from
	* the platform code.
	*/
	if (WARN_ON_ONCE(!dev->get_clk_rate_khz))
	return 0;
	return dev->get_clk_rate_khz(dev);
	}

	int i2c_dw_prepare_clk(struct dw_i2c_dev *dev, bool prepare)
	{
	int ret;

	if (IS_ERR(dev->clk))
	return PTR_ERR(dev->clk);

	if (prepare) {
	/* Optional interface clock */
	ret = clk_prepare_enable(dev->pclk);
	if (ret)
	return ret;

	ret = clk_prepare_enable(dev->clk);
	if (ret)
	clk_disable_unprepare(dev->pclk);

	return ret;
	}

	clk_disable_unprepare(dev->clk);
	clk_disable_unprepare(dev->pclk);

	return 0;
	}
	EXPORT_SYMBOL_GPL(i2c_dw_prepare_clk);

	int i2c_dw_acquire_lock(struct dw_i2c_dev *dev)
	{
	int ret;

	if (!dev->acquire_lock)
	return 0;

	ret = dev->acquire_lock();
	if (!ret)
	return 0;

	dev_err(dev->dev, "couldn't acquire bus ownership\n");

	return ret;
	}

	void i2c_dw_release_lock(struct dw_i2c_dev *dev)
	{
	if (dev->release_lock)
	dev->release_lock();
	}

	/*
	* Waiting for bus not busy
	*/
	int i2c_dw_wait_bus_not_busy(struct dw_i2c_dev *dev)
	{
	int timeout = TIMEOUT;

	while (dw_readl(dev, DW_IC_STATUS) & DW_IC_STATUS_ACTIVITY) {
	if (timeout <= 0) {
	dev_warn(dev->dev, "timeout waiting for bus ready\n");
	i2c_recover_bus(&dev->adapter);

	if (dw_readl(dev, DW_IC_STATUS) & DW_IC_STATUS_ACTIVITY)
	return -ETIMEDOUT;
	return 0;
	}
	timeout--;
	usleep_range(1000, 1100);
	}

	return 0;
	}

	int i2c_dw_handle_tx_abort(struct dw_i2c_dev *dev)
	{
	unsigned long abort_source = dev->abort_source;
	int i;

	if (abort_source & DW_IC_TX_ABRT_NOACK) {
	for_each_set_bit(i, &abort_source, ARRAY_SIZE(abort_sources))
	dev_dbg(dev->dev,
	"%s: %s\n", __func__, abort_sources[i]);
	return -EREMOTEIO;
	}

	for_each_set_bit(i, &abort_source, ARRAY_SIZE(abort_sources))
	dev_err(dev->dev, "%s: %s\n", __func__, abort_sources[i]);

	if (abort_source & DW_IC_TX_ARB_LOST)
	return -EAGAIN;
	else if (abort_source & DW_IC_TX_ABRT_GCALL_READ)
	return -EINVAL; /* wrong msgs[] data */
	else
	return -EIO;
	}

	u32 i2c_dw_func(struct i2c_adapter *adap)
	{
	struct dw_i2c_dev *dev = i2c_get_adapdata(adap);

	return dev->functionality;
	}

	void i2c_dw_disable(struct dw_i2c_dev *dev)
	{
	/* Disable controller */
	__i2c_dw_disable(dev);

	/* Disable all interupts */
	dw_writel(dev, 0, DW_IC_INTR_MASK);
	dw_readl(dev, DW_IC_CLR_INTR);
	}

	void i2c_dw_disable_int(struct dw_i2c_dev *dev)
	{
	dw_writel(dev, 0, DW_IC_INTR_MASK);
	}

	u32 i2c_dw_read_comp_param(struct dw_i2c_dev *dev)
	{
	return dw_readl(dev, DW_IC_COMP_PARAM_1);
	}
	EXPORT_SYMBOL_GPL(i2c_dw_read_comp_param);

	MODULE_DESCRIPTION("Synopsys DesignWare I2C bus adapter core");
	MODULE_LICENSE("GPL");