drivers/i2c/busses/i2c-designware-slave.c - arm/linux - Git at Google

 /*
  * Synopsys DesignWare I2C adapter driver (slave only).
  *
  * Based on the Synopsys DesignWare I2C adapter driver (master).
  *
  * Copyright (C) 2016 Synopsys 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.
  * ----------------------------------------------------------------------------
  *
  */
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/pm_runtime.h>

 #include "i2c-designware-core.h"

 static void i2c_dw_configure_fifo_slave(struct dw_i2c_dev *dev)
 {
 	/* Configure Tx/Rx FIFO threshold levels. */
 	dw_writel(dev, 0, DW_IC_TX_TL);
 	dw_writel(dev, 0, DW_IC_RX_TL);

 	/* Configure the I2C slave. */
 	dw_writel(dev, dev->slave_cfg, DW_IC_CON);
 	dw_writel(dev, DW_IC_INTR_SLAVE_MASK, DW_IC_INTR_MASK);
 }

 /**
  * i2c_dw_init_slave() - Initialize the designware i2c slave hardware
  * @dev: device private data
  *
  * This function configures and enables the I2C in slave mode.
  * This function is called during I2C init function, and in case of timeout at
  * run time.
  */
 static int i2c_dw_init_slave(struct dw_i2c_dev *dev)
 {
 	u32 sda_falling_time, scl_falling_time;
 	u32 reg, comp_param1;
 	u32 hcnt, lcnt;
 	int ret;

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

 	reg = dw_readl(dev, DW_IC_COMP_TYPE);
 	if (reg == ___constant_swab32(DW_IC_COMP_TYPE_VALUE)) {
 		/* Configure register endianness 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);
 		i2c_dw_release_lock(dev);
 		return -ENODEV;
 	}

 	comp_param1 = dw_readl(dev, DW_IC_COMP_PARAM_1);

 	/* Disable the adapter. */
 	__i2c_dw_enable_and_wait(dev, false);

 	/* Set standard and fast speed deviders for high/low periods. */
 	sda_falling_time = dev->sda_falling_time ?: 300; /* ns */
 	scl_falling_time = dev->scl_falling_time ?: 300; /* ns */

 	/* Set SCL timing parameters for standard-mode. */
 	if (dev->ss_hcnt && dev->ss_lcnt) {
 		hcnt = dev->ss_hcnt;
 		lcnt = dev->ss_lcnt;
 	} else {
 		hcnt = i2c_dw_scl_hcnt(i2c_dw_clk_rate(dev),
 				       4000,	/* tHD;STA = tHIGH = 4.0 us */
 				       sda_falling_time,
 				       0,	/* 0: DW default, 1: Ideal */
 				       0);	/* No offset */
 		lcnt = i2c_dw_scl_lcnt(i2c_dw_clk_rate(dev),
 				       4700,	/* tLOW = 4.7 us */
 				       scl_falling_time,
 				       0);	/* No offset */
 	}
 	dw_writel(dev, hcnt, DW_IC_SS_SCL_HCNT);
 	dw_writel(dev, lcnt, DW_IC_SS_SCL_LCNT);
 	dev_dbg(dev->dev, "Standard-mode HCNT:LCNT = %d:%d\n", hcnt, lcnt);

 	/* Set SCL timing parameters for fast-mode or fast-mode plus. */
 	if ((dev->clk_freq == 1000000) && dev->fp_hcnt && dev->fp_lcnt) {
 		hcnt = dev->fp_hcnt;
 		lcnt = dev->fp_lcnt;
 	} else if (dev->fs_hcnt && dev->fs_lcnt) {
 		hcnt = dev->fs_hcnt;
 		lcnt = dev->fs_lcnt;
 	} else {
 		hcnt = i2c_dw_scl_hcnt(i2c_dw_clk_rate(dev),
 				       600,	/* tHD;STA = tHIGH = 0.6 us */
 				       sda_falling_time,
 				       0,	/* 0: DW default, 1: Ideal */
 				       0);	/* No offset */
 		lcnt = i2c_dw_scl_lcnt(i2c_dw_clk_rate(dev),
 				       1300,	/* tLOW = 1.3 us */
 				       scl_falling_time,
 				       0);	/* No offset */
 	}
 	dw_writel(dev, hcnt, DW_IC_FS_SCL_HCNT);
 	dw_writel(dev, lcnt, DW_IC_FS_SCL_LCNT);
 	dev_dbg(dev->dev, "Fast-mode HCNT:LCNT = %d:%d\n", hcnt, lcnt);

 	if ((dev->slave_cfg & DW_IC_CON_SPEED_MASK) ==
 		DW_IC_CON_SPEED_HIGH) {
 		if ((comp_param1 & DW_IC_COMP_PARAM_1_SPEED_MODE_MASK)
 			!= DW_IC_COMP_PARAM_1_SPEED_MODE_HIGH) {
 			dev_err(dev->dev, "High Speed not supported!\n");
 			dev->slave_cfg &= ~DW_IC_CON_SPEED_MASK;
 			dev->slave_cfg |= DW_IC_CON_SPEED_FAST;
 		} else if (dev->hs_hcnt && dev->hs_lcnt) {
 			hcnt = dev->hs_hcnt;
 			lcnt = dev->hs_lcnt;
 			dw_writel(dev, hcnt, DW_IC_HS_SCL_HCNT);
 			dw_writel(dev, lcnt, DW_IC_HS_SCL_LCNT);
 			dev_dbg(dev->dev, "HighSpeed-mode HCNT:LCNT = %d:%d\n",
 				hcnt, lcnt);
 		}
 	}

 	/* 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;
 		dw_writel(dev, dev->sda_hold_time, DW_IC_SDA_HOLD);
 	} else {
 		dev_warn(dev->dev,
 			 "Hardware too old to adjust SDA hold time.\n");
 	}

 	i2c_dw_configure_fifo_slave(dev);
 	i2c_dw_release_lock(dev);

 	return 0;
 }

 static int i2c_dw_reg_slave(struct i2c_client *slave)
 {
 	struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter);

 	if (dev->slave)
 		return -EBUSY;
 	if (slave->flags & I2C_CLIENT_TEN)
 		return -EAFNOSUPPORT;
 	pm_runtime_get_sync(dev->dev);

 	/*
 	 * Set slave address in the IC_SAR register,
 	 * the address to which the DW_apb_i2c responds.
 	 */
 	__i2c_dw_enable(dev, false);
 	dw_writel(dev, slave->addr, DW_IC_SAR);
 	dev->slave = slave;

 	__i2c_dw_enable(dev, true);

 	dev->cmd_err = 0;
 	dev->msg_write_idx = 0;
 	dev->msg_read_idx = 0;
 	dev->msg_err = 0;
 	dev->status = STATUS_IDLE;
 	dev->abort_source = 0;
 	dev->rx_outstanding = 0;

 	return 0;
 }

 static int i2c_dw_unreg_slave(struct i2c_client *slave)
 {
 	struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter);

 	dev->disable_int(dev);
 	dev->disable(dev);
 	dev->slave = NULL;
 	pm_runtime_put(dev->dev);

 	return 0;
 }

 static u32 i2c_dw_read_clear_intrbits_slave(struct dw_i2c_dev *dev)
 {
 	u32 stat;

 	/*
 	 * The IC_INTR_STAT register just indicates "enabled" interrupts.
 	 * Ths unmasked raw version of interrupt status bits are available
 	 * in the IC_RAW_INTR_STAT register.
 	 *
 	 * That is,
 	 *   stat = dw_readl(IC_INTR_STAT);
 	 * equals to,
 	 *   stat = dw_readl(IC_RAW_INTR_STAT) & dw_readl(IC_INTR_MASK);
 	 *
 	 * The raw version might be useful for debugging purposes.
 	 */
 	stat = dw_readl(dev, DW_IC_INTR_STAT);

 	/*
 	 * Do not use the IC_CLR_INTR register to clear interrupts, or
 	 * you'll miss some interrupts, triggered during the period from
 	 * dw_readl(IC_INTR_STAT) to dw_readl(IC_CLR_INTR).
 	 *
 	 * Instead, use the separately-prepared IC_CLR_* registers.
 	 */
 	if (stat & DW_IC_INTR_TX_ABRT)
 		dw_readl(dev, DW_IC_CLR_TX_ABRT);
 	if (stat & DW_IC_INTR_RX_UNDER)
 		dw_readl(dev, DW_IC_CLR_RX_UNDER);
 	if (stat & DW_IC_INTR_RX_OVER)
 		dw_readl(dev, DW_IC_CLR_RX_OVER);
 	if (stat & DW_IC_INTR_TX_OVER)
 		dw_readl(dev, DW_IC_CLR_TX_OVER);
 	if (stat & DW_IC_INTR_RX_DONE)
 		dw_readl(dev, DW_IC_CLR_RX_DONE);
 	if (stat & DW_IC_INTR_ACTIVITY)
 		dw_readl(dev, DW_IC_CLR_ACTIVITY);
 	if (stat & DW_IC_INTR_STOP_DET)
 		dw_readl(dev, DW_IC_CLR_STOP_DET);
 	if (stat & DW_IC_INTR_START_DET)
 		dw_readl(dev, DW_IC_CLR_START_DET);
 	if (stat & DW_IC_INTR_GEN_CALL)
 		dw_readl(dev, DW_IC_CLR_GEN_CALL);

 	return stat;
 }

 /*
  * Interrupt service routine. This gets called whenever an I2C slave interrupt
  * occurs.
  */

 static int i2c_dw_irq_handler_slave(struct dw_i2c_dev *dev)
 {
 	u32 raw_stat, stat, enabled;
 	u8 val, slave_activity;

 	stat = dw_readl(dev, DW_IC_INTR_STAT);
 	enabled = dw_readl(dev, DW_IC_ENABLE);
 	raw_stat = dw_readl(dev, DW_IC_RAW_INTR_STAT);
 	slave_activity = ((dw_readl(dev, DW_IC_STATUS) &
 		DW_IC_STATUS_SLAVE_ACTIVITY) >> 6);

 	if (!enabled || !(raw_stat & ~DW_IC_INTR_ACTIVITY) || !dev->slave)
 		return 0;

 	dev_dbg(dev->dev,
 		"%#x STATUS SLAVE_ACTIVITY=%#x : RAW_INTR_STAT=%#x : INTR_STAT=%#x\n",
 		enabled, slave_activity, raw_stat, stat);

 	if ((stat & DW_IC_INTR_RX_FULL) && (stat & DW_IC_INTR_STOP_DET))
 		i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_REQUESTED, &val);

 	if (stat & DW_IC_INTR_RD_REQ) {
 		if (slave_activity) {
 			if (stat & DW_IC_INTR_RX_FULL) {
 				val = dw_readl(dev, DW_IC_DATA_CMD);

 				if (!i2c_slave_event(dev->slave,
 						     I2C_SLAVE_WRITE_RECEIVED,
 						     &val)) {
 					dev_vdbg(dev->dev, "Byte %X acked!",
 						 val);
 				}
 				dw_readl(dev, DW_IC_CLR_RD_REQ);
 				stat = i2c_dw_read_clear_intrbits_slave(dev);
 			} else {
 				dw_readl(dev, DW_IC_CLR_RD_REQ);
 				dw_readl(dev, DW_IC_CLR_RX_UNDER);
 				stat = i2c_dw_read_clear_intrbits_slave(dev);
 			}
 			if (!i2c_slave_event(dev->slave,
 					     I2C_SLAVE_READ_REQUESTED,
 					     &val))
 				dw_writel(dev, val, DW_IC_DATA_CMD);
 		}
 	}

 	if (stat & DW_IC_INTR_RX_DONE) {
 		if (!i2c_slave_event(dev->slave, I2C_SLAVE_READ_PROCESSED,
 				     &val))
 			dw_readl(dev, DW_IC_CLR_RX_DONE);

 		i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &val);
 		stat = i2c_dw_read_clear_intrbits_slave(dev);
 		return 1;
 	}

 	if (stat & DW_IC_INTR_RX_FULL) {
 		val = dw_readl(dev, DW_IC_DATA_CMD);
 		if (!i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED,
 				     &val))
 			dev_vdbg(dev->dev, "Byte %X acked!", val);
 	} else {
 		i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &val);
 		stat = i2c_dw_read_clear_intrbits_slave(dev);
 	}

 	return 1;
 }

 static irqreturn_t i2c_dw_isr_slave(int this_irq, void *dev_id)
 {
 	struct dw_i2c_dev *dev = dev_id;
 	int ret;

 	i2c_dw_read_clear_intrbits_slave(dev);
 	ret = i2c_dw_irq_handler_slave(dev);
 	if (ret > 0)
 		complete(&dev->cmd_complete);

 	return IRQ_RETVAL(ret);
 }

 static const struct i2c_algorithm i2c_dw_algo = {
 	.functionality = i2c_dw_func,
 	.reg_slave = i2c_dw_reg_slave,
 	.unreg_slave = i2c_dw_unreg_slave,
 };

 int i2c_dw_probe_slave(struct dw_i2c_dev *dev)
 {
 	struct i2c_adapter *adap = &dev->adapter;
 	int ret;

 	init_completion(&dev->cmd_complete);

 	dev->init = i2c_dw_init_slave;
 	dev->disable = i2c_dw_disable;
 	dev->disable_int = i2c_dw_disable_int;

 	ret = dev->init(dev);
 	if (ret)
 		return ret;

 	snprintf(adap->name, sizeof(adap->name),
 		 "Synopsys DesignWare I2C Slave adapter");
 	adap->retries = 3;
 	adap->algo = &i2c_dw_algo;
 	adap->dev.parent = dev->dev;
 	i2c_set_adapdata(adap, dev);

 	ret = devm_request_irq(dev->dev, dev->irq, i2c_dw_isr_slave,
 			       IRQF_SHARED, dev_name(dev->dev), dev);
 	if (ret) {
 		dev_err(dev->dev, "failure requesting irq %i: %d\n",
 			dev->irq, ret);
 		return ret;
 	}

 	ret = i2c_add_numbered_adapter(adap);
 	if (ret)
 		dev_err(dev->dev, "failure adding adapter: %d\n", ret);

 	return ret;
 }
 EXPORT_SYMBOL_GPL(i2c_dw_probe_slave);

 MODULE_AUTHOR("Luis Oliveira <lolivei@synopsys.com>");
 MODULE_DESCRIPTION("Synopsys DesignWare I2C bus slave adapter");
 MODULE_LICENSE("GPL v2");
	/*
	* Synopsys DesignWare I2C adapter driver (slave only).
	*
	* Based on the Synopsys DesignWare I2C adapter driver (master).
	*
	* Copyright (C) 2016 Synopsys 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.
	* ----------------------------------------------------------------------------
	*
	*/
	#include <linux/delay.h>
	#include <linux/err.h>
	#include <linux/errno.h>
	#include <linux/i2c.h>
	#include <linux/interrupt.h>
	#include <linux/io.h>
	#include <linux/module.h>
	#include <linux/pm_runtime.h>

	#include "i2c-designware-core.h"

	static void i2c_dw_configure_fifo_slave(struct dw_i2c_dev *dev)
	{
	/* Configure Tx/Rx FIFO threshold levels. */
	dw_writel(dev, 0, DW_IC_TX_TL);
	dw_writel(dev, 0, DW_IC_RX_TL);

	/* Configure the I2C slave. */
	dw_writel(dev, dev->slave_cfg, DW_IC_CON);
	dw_writel(dev, DW_IC_INTR_SLAVE_MASK, DW_IC_INTR_MASK);
	}

	/**
	* i2c_dw_init_slave() - Initialize the designware i2c slave hardware
	* @dev: device private data
	*
	* This function configures and enables the I2C in slave mode.
	* This function is called during I2C init function, and in case of timeout at
	* run time.
	*/
	static int i2c_dw_init_slave(struct dw_i2c_dev *dev)
	{
	u32 sda_falling_time, scl_falling_time;
	u32 reg, comp_param1;
	u32 hcnt, lcnt;
	int ret;

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

	reg = dw_readl(dev, DW_IC_COMP_TYPE);
	if (reg == ___constant_swab32(DW_IC_COMP_TYPE_VALUE)) {
	/* Configure register endianness 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);
	i2c_dw_release_lock(dev);
	return -ENODEV;
	}

	comp_param1 = dw_readl(dev, DW_IC_COMP_PARAM_1);

	/* Disable the adapter. */
	__i2c_dw_enable_and_wait(dev, false);

	/* Set standard and fast speed deviders for high/low periods. */
	sda_falling_time = dev->sda_falling_time ?: 300; /* ns */
	scl_falling_time = dev->scl_falling_time ?: 300; /* ns */

	/* Set SCL timing parameters for standard-mode. */
	if (dev->ss_hcnt && dev->ss_lcnt) {
	hcnt = dev->ss_hcnt;
	lcnt = dev->ss_lcnt;
	} else {
	hcnt = i2c_dw_scl_hcnt(i2c_dw_clk_rate(dev),
	4000, /* tHD;STA = tHIGH = 4.0 us */
	sda_falling_time,
	0, /* 0: DW default, 1: Ideal */
	0); /* No offset */
	lcnt = i2c_dw_scl_lcnt(i2c_dw_clk_rate(dev),
	4700, /* tLOW = 4.7 us */
	scl_falling_time,
	0); /* No offset */
	}
	dw_writel(dev, hcnt, DW_IC_SS_SCL_HCNT);
	dw_writel(dev, lcnt, DW_IC_SS_SCL_LCNT);
	dev_dbg(dev->dev, "Standard-mode HCNT:LCNT = %d:%d\n", hcnt, lcnt);

	/* Set SCL timing parameters for fast-mode or fast-mode plus. */
	if ((dev->clk_freq == 1000000) && dev->fp_hcnt && dev->fp_lcnt) {
	hcnt = dev->fp_hcnt;
	lcnt = dev->fp_lcnt;
	} else if (dev->fs_hcnt && dev->fs_lcnt) {
	hcnt = dev->fs_hcnt;
	lcnt = dev->fs_lcnt;
	} else {
	hcnt = i2c_dw_scl_hcnt(i2c_dw_clk_rate(dev),
	600, /* tHD;STA = tHIGH = 0.6 us */
	sda_falling_time,
	0, /* 0: DW default, 1: Ideal */
	0); /* No offset */
	lcnt = i2c_dw_scl_lcnt(i2c_dw_clk_rate(dev),
	1300, /* tLOW = 1.3 us */
	scl_falling_time,
	0); /* No offset */
	}
	dw_writel(dev, hcnt, DW_IC_FS_SCL_HCNT);
	dw_writel(dev, lcnt, DW_IC_FS_SCL_LCNT);
	dev_dbg(dev->dev, "Fast-mode HCNT:LCNT = %d:%d\n", hcnt, lcnt);

	if ((dev->slave_cfg & DW_IC_CON_SPEED_MASK) ==
	DW_IC_CON_SPEED_HIGH) {
	if ((comp_param1 & DW_IC_COMP_PARAM_1_SPEED_MODE_MASK)
	!= DW_IC_COMP_PARAM_1_SPEED_MODE_HIGH) {
	dev_err(dev->dev, "High Speed not supported!\n");
	dev->slave_cfg &= ~DW_IC_CON_SPEED_MASK;
	dev->slave_cfg \|= DW_IC_CON_SPEED_FAST;
	} else if (dev->hs_hcnt && dev->hs_lcnt) {
	hcnt = dev->hs_hcnt;
	lcnt = dev->hs_lcnt;
	dw_writel(dev, hcnt, DW_IC_HS_SCL_HCNT);
	dw_writel(dev, lcnt, DW_IC_HS_SCL_LCNT);
	dev_dbg(dev->dev, "HighSpeed-mode HCNT:LCNT = %d:%d\n",
	hcnt, lcnt);
	}
	}

	/* 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;
	dw_writel(dev, dev->sda_hold_time, DW_IC_SDA_HOLD);
	} else {
	dev_warn(dev->dev,
	"Hardware too old to adjust SDA hold time.\n");
	}

	i2c_dw_configure_fifo_slave(dev);
	i2c_dw_release_lock(dev);

	return 0;
	}

	static int i2c_dw_reg_slave(struct i2c_client *slave)
	{
	struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter);

	if (dev->slave)
	return -EBUSY;
	if (slave->flags & I2C_CLIENT_TEN)
	return -EAFNOSUPPORT;
	pm_runtime_get_sync(dev->dev);

	/*
	* Set slave address in the IC_SAR register,
	* the address to which the DW_apb_i2c responds.
	*/
	__i2c_dw_enable(dev, false);
	dw_writel(dev, slave->addr, DW_IC_SAR);
	dev->slave = slave;

	__i2c_dw_enable(dev, true);

	dev->cmd_err = 0;
	dev->msg_write_idx = 0;
	dev->msg_read_idx = 0;
	dev->msg_err = 0;
	dev->status = STATUS_IDLE;
	dev->abort_source = 0;
	dev->rx_outstanding = 0;

	return 0;
	}

	static int i2c_dw_unreg_slave(struct i2c_client *slave)
	{
	struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter);

	dev->disable_int(dev);
	dev->disable(dev);
	dev->slave = NULL;
	pm_runtime_put(dev->dev);

	return 0;
	}

	static u32 i2c_dw_read_clear_intrbits_slave(struct dw_i2c_dev *dev)
	{
	u32 stat;

	/*
	* The IC_INTR_STAT register just indicates "enabled" interrupts.
	* Ths unmasked raw version of interrupt status bits are available
	* in the IC_RAW_INTR_STAT register.
	*
	* That is,
	* stat = dw_readl(IC_INTR_STAT);
	* equals to,
	* stat = dw_readl(IC_RAW_INTR_STAT) & dw_readl(IC_INTR_MASK);
	*
	* The raw version might be useful for debugging purposes.
	*/
	stat = dw_readl(dev, DW_IC_INTR_STAT);

	/*
	* Do not use the IC_CLR_INTR register to clear interrupts, or
	* you'll miss some interrupts, triggered during the period from
	* dw_readl(IC_INTR_STAT) to dw_readl(IC_CLR_INTR).
	*
	* Instead, use the separately-prepared IC_CLR_* registers.
	*/
	if (stat & DW_IC_INTR_TX_ABRT)
	dw_readl(dev, DW_IC_CLR_TX_ABRT);
	if (stat & DW_IC_INTR_RX_UNDER)
	dw_readl(dev, DW_IC_CLR_RX_UNDER);
	if (stat & DW_IC_INTR_RX_OVER)
	dw_readl(dev, DW_IC_CLR_RX_OVER);
	if (stat & DW_IC_INTR_TX_OVER)
	dw_readl(dev, DW_IC_CLR_TX_OVER);
	if (stat & DW_IC_INTR_RX_DONE)
	dw_readl(dev, DW_IC_CLR_RX_DONE);
	if (stat & DW_IC_INTR_ACTIVITY)
	dw_readl(dev, DW_IC_CLR_ACTIVITY);
	if (stat & DW_IC_INTR_STOP_DET)
	dw_readl(dev, DW_IC_CLR_STOP_DET);
	if (stat & DW_IC_INTR_START_DET)
	dw_readl(dev, DW_IC_CLR_START_DET);
	if (stat & DW_IC_INTR_GEN_CALL)
	dw_readl(dev, DW_IC_CLR_GEN_CALL);

	return stat;
	}

	/*
	* Interrupt service routine. This gets called whenever an I2C slave interrupt
	* occurs.
	*/

	static int i2c_dw_irq_handler_slave(struct dw_i2c_dev *dev)
	{
	u32 raw_stat, stat, enabled;
	u8 val, slave_activity;

	stat = dw_readl(dev, DW_IC_INTR_STAT);
	enabled = dw_readl(dev, DW_IC_ENABLE);
	raw_stat = dw_readl(dev, DW_IC_RAW_INTR_STAT);
	slave_activity = ((dw_readl(dev, DW_IC_STATUS) &
	DW_IC_STATUS_SLAVE_ACTIVITY) >> 6);

	if (!enabled \|\| !(raw_stat & ~DW_IC_INTR_ACTIVITY) \|\| !dev->slave)
	return 0;

	dev_dbg(dev->dev,
	"%#x STATUS SLAVE_ACTIVITY=%#x : RAW_INTR_STAT=%#x : INTR_STAT=%#x\n",
	enabled, slave_activity, raw_stat, stat);

	if ((stat & DW_IC_INTR_RX_FULL) && (stat & DW_IC_INTR_STOP_DET))
	i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_REQUESTED, &val);

	if (stat & DW_IC_INTR_RD_REQ) {
	if (slave_activity) {
	if (stat & DW_IC_INTR_RX_FULL) {
	val = dw_readl(dev, DW_IC_DATA_CMD);

	if (!i2c_slave_event(dev->slave,
	I2C_SLAVE_WRITE_RECEIVED,
	&val)) {
	dev_vdbg(dev->dev, "Byte %X acked!",
	val);
	}
	dw_readl(dev, DW_IC_CLR_RD_REQ);
	stat = i2c_dw_read_clear_intrbits_slave(dev);
	} else {
	dw_readl(dev, DW_IC_CLR_RD_REQ);
	dw_readl(dev, DW_IC_CLR_RX_UNDER);
	stat = i2c_dw_read_clear_intrbits_slave(dev);
	}
	if (!i2c_slave_event(dev->slave,
	I2C_SLAVE_READ_REQUESTED,
	&val))
	dw_writel(dev, val, DW_IC_DATA_CMD);
	}
	}

	if (stat & DW_IC_INTR_RX_DONE) {
	if (!i2c_slave_event(dev->slave, I2C_SLAVE_READ_PROCESSED,
	&val))
	dw_readl(dev, DW_IC_CLR_RX_DONE);

	i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &val);
	stat = i2c_dw_read_clear_intrbits_slave(dev);
	return 1;
	}

	if (stat & DW_IC_INTR_RX_FULL) {
	val = dw_readl(dev, DW_IC_DATA_CMD);
	if (!i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED,
	&val))
	dev_vdbg(dev->dev, "Byte %X acked!", val);
	} else {
	i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &val);
	stat = i2c_dw_read_clear_intrbits_slave(dev);
	}

	return 1;
	}

	static irqreturn_t i2c_dw_isr_slave(int this_irq, void *dev_id)
	{
	struct dw_i2c_dev *dev = dev_id;
	int ret;

	i2c_dw_read_clear_intrbits_slave(dev);
	ret = i2c_dw_irq_handler_slave(dev);
	if (ret > 0)
	complete(&dev->cmd_complete);

	return IRQ_RETVAL(ret);
	}

	static const struct i2c_algorithm i2c_dw_algo = {
	.functionality = i2c_dw_func,
	.reg_slave = i2c_dw_reg_slave,
	.unreg_slave = i2c_dw_unreg_slave,
	};

	int i2c_dw_probe_slave(struct dw_i2c_dev *dev)
	{
	struct i2c_adapter *adap = &dev->adapter;
	int ret;

	init_completion(&dev->cmd_complete);

	dev->init = i2c_dw_init_slave;
	dev->disable = i2c_dw_disable;
	dev->disable_int = i2c_dw_disable_int;

	ret = dev->init(dev);
	if (ret)
	return ret;

	snprintf(adap->name, sizeof(adap->name),
	"Synopsys DesignWare I2C Slave adapter");
	adap->retries = 3;
	adap->algo = &i2c_dw_algo;
	adap->dev.parent = dev->dev;
	i2c_set_adapdata(adap, dev);

	ret = devm_request_irq(dev->dev, dev->irq, i2c_dw_isr_slave,
	IRQF_SHARED, dev_name(dev->dev), dev);
	if (ret) {
	dev_err(dev->dev, "failure requesting irq %i: %d\n",
	dev->irq, ret);
	return ret;
	}

	ret = i2c_add_numbered_adapter(adap);
	if (ret)
	dev_err(dev->dev, "failure adding adapter: %d\n", ret);

	return ret;
	}
	EXPORT_SYMBOL_GPL(i2c_dw_probe_slave);

	MODULE_AUTHOR("Luis Oliveira <lolivei@synopsys.com>");
	MODULE_DESCRIPTION("Synopsys DesignWare I2C bus slave adapter");
	MODULE_LICENSE("GPL v2");