cpu/ppc4xx/i2c.c - platform/external/u-boot - Gitiles

 /*****************************************************************************/
 /* I2C Bus interface initialisation and I2C Commands                         */
 /* for PPC405GP		                                                     */
 /* Author : AS HARNOIS                                                       */
 /* Date   : 13.Dec.00                                                        */
 /*****************************************************************************/

 #include <common.h>
 #include <ppc4xx.h>
 #if defined(CONFIG_440)
 #   include <440_i2c.h>
 #else
 #   include <405gp_i2c.h>
 #endif
 #include <i2c.h>

 #ifdef CONFIG_HARD_I2C

 #define IIC_OK		0
 #define IIC_NOK		1
 #define IIC_NOK_LA	2		/* Lost arbitration */
 #define IIC_NOK_ICT	3		/* Incomplete transfer */
 #define IIC_NOK_XFRA	4		/* Transfer aborted */
 #define IIC_NOK_DATA	5		/* No data in buffer */
 #define IIC_NOK_TOUT	6		/* Transfer timeout */

 #define IIC_TIMEOUT 1			/* 1 seconde */


 static void _i2c_bus_reset (void)
 {
 	int i, status;

 	/* Reset status register */
 	/* write 1 in SCMP and IRQA to clear these fields */
 	out8 (IIC_STS, 0x0A);

 	/* write 1 in IRQP IRQD LA ICT XFRA to clear these fields */
 	out8 (IIC_EXTSTS, 0x8F);
 	__asm__ volatile ("eieio");

 	/*
 	 * Get current state, reset bus
 	 * only if no transfers are pending.
 	 */
 	i = 10;
 	do {
 		/* Get status */
 		status = in8 (IIC_STS);
 		udelay (500);			/* 500us */
 		i--;
 	} while ((status & IIC_STS_PT) && (i > 0));
 	/* Soft reset controller */
 	status = in8 (IIC_XTCNTLSS);
 	out8 (IIC_XTCNTLSS, (status | IIC_XTCNTLSS_SRST));
 	__asm__ volatile ("eieio");

 	/* make sure where in initial state, data hi, clock hi */
 	out8 (IIC_DIRECTCNTL, 0xC);
 	for (i = 0; i < 10; i++) {
 		if ((in8 (IIC_DIRECTCNTL) & 0x3) != 0x3) {
 			/* clock until we get to known state */
 			out8 (IIC_DIRECTCNTL, 0x8);	/* clock lo */
 			udelay (100);		/* 100us */
 			out8 (IIC_DIRECTCNTL, 0xC);	/* clock hi */
 			udelay (100);		/* 100us */
 		} else {
 			break;
 		}
 	}
 	/* send start condition */
 	out8 (IIC_DIRECTCNTL, 0x4);
 	udelay (1000);				/* 1ms */
 	/* send stop condition */
 	out8 (IIC_DIRECTCNTL, 0xC);
 	udelay (1000);				/* 1ms */
 	/* Unreset controller */
 	out8 (IIC_XTCNTLSS, (status & ~IIC_XTCNTLSS_SRST));
 	udelay (1000);				/* 1ms */
 }

 void i2c_init (int speed, int slaveadd)
 {
 	sys_info_t sysInfo;
 	unsigned long freqOPB;
 	int val, divisor;

 #ifdef CFG_I2C_INIT_BOARD
 	/* call board specific i2c bus reset routine before accessing the   */
 	/* environment, which might be in a chip on that bus. For details   */
 	/* about this problem see doc/I2C_Edge_Conditions.                  */
 	i2c_init_board();
 #endif

 	/* Handle possible failed I2C state */
 	/* FIXME: put this into i2c_init_board()? */
 	_i2c_bus_reset ();

 	/* clear lo master address */
 	out8 (IIC_LMADR, 0);

 	/* clear hi master address */
 	out8 (IIC_HMADR, 0);

 	/* clear lo slave address */
 	out8 (IIC_LSADR, 0);

 	/* clear hi slave address */
 	out8 (IIC_HSADR, 0);

 	/* Clock divide Register */
 	/* get OPB frequency */
 	get_sys_info (&sysInfo);
 	freqOPB = sysInfo.freqPLB / sysInfo.pllOpbDiv;
 	/* set divisor according to freqOPB */
 	divisor = (freqOPB - 1) / 10000000;
 	if (divisor == 0)
 		divisor = 1;
 	out8 (IIC_CLKDIV, divisor);

 	/* no interrupts */
 	out8 (IIC_INTRMSK, 0);

 	/* clear transfer count */
 	out8 (IIC_XFRCNT, 0);

 	/* clear extended control & stat */
 	/* write 1 in SRC SRS SWC SWS to clear these fields */
 	out8 (IIC_XTCNTLSS, 0xF0);

 	/* Mode Control Register
 	   Flush Slave/Master data buffer */
 	out8 (IIC_MDCNTL, IIC_MDCNTL_FSDB | IIC_MDCNTL_FMDB);
 	__asm__ volatile ("eieio");


 	val = in8(IIC_MDCNTL);
 	__asm__ volatile ("eieio");

 	/* Ignore General Call, slave transfers are ignored,
 	   disable interrupts, exit unknown bus state, enable hold
 	   SCL
 	   100kHz normaly or FastMode for 400kHz and above
 	*/

 	val |= IIC_MDCNTL_EUBS|IIC_MDCNTL_HSCL;
 	if( speed >= 400000 ){
 		val |= IIC_MDCNTL_FSM;
 	}
 	out8 (IIC_MDCNTL, val);

 	/* clear control reg */
 	out8 (IIC_CNTL, 0x00);
 	__asm__ volatile ("eieio");

 }

 /*
   This code tries to use the features of the 405GP i2c
   controller. It will transfer up to 4 bytes in one pass
   on the loop. It only does out8(lbz) to the buffer when it
   is possible to do out16(lhz) transfers.

   cmd_type is 0 for write 1 for read.

   addr_len can take any value from 0-255, it is only limited
   by the char, we could make it larger if needed. If it is
   0 we skip the address write cycle.

   Typical case is a Write of an addr followd by a Read. The
   IBM FAQ does not cover this. On the last byte of the write
   we don't set the creg CHT bit, and on the first bytes of the
   read we set the RPST bit.

   It does not support address only transfers, there must be
   a data part. If you want to write the address yourself, put
   it in the data pointer.

   It does not support transfer to/from address 0.

   It does not check XFRCNT.
 */
 static
 int i2c_transfer(unsigned char cmd_type,
 		 unsigned char chip,
 		 unsigned char addr[],
 		 unsigned char addr_len,
 		 unsigned char data[],
 		 unsigned short data_len )
 {
 	unsigned char* ptr;
 	int reading;
 	int tran,cnt;
 	int result;
 	int status;
 	int i;
 	uchar creg;

 	if( data == 0 || data_len == 0 ){
 		/*Don't support data transfer of no length or to address 0*/
 		printf( "i2c_transfer: bad call\n" );
 		return IIC_NOK;
 	}
 	if( addr && addr_len ){
 		ptr = addr;
 		cnt = addr_len;
 		reading = 0;
 	}else{
 		ptr = data;
 		cnt = data_len;
 		reading = cmd_type;
 	}

 	/*Clear Stop Complete Bit*/
 	out8(IIC_STS,IIC_STS_SCMP);
 	/* Check init */
 	i=10;
 	do {
 		/* Get status */
 		status = in8(IIC_STS);
 		__asm__ volatile("eieio");
 		i--;
 	} while ((status & IIC_STS_PT) && (i>0));

 	if (status & IIC_STS_PT) {
 		result = IIC_NOK_TOUT;
 		return(result);
 	}
 	/*flush the Master/Slave Databuffers*/
 	out8(IIC_MDCNTL, ((in8(IIC_MDCNTL))|IIC_MDCNTL_FMDB|IIC_MDCNTL_FSDB));
 	/*need to wait 4 OPB clocks? code below should take that long*/

 	/* 7-bit adressing */
 	out8(IIC_HMADR,0);
 	out8(IIC_LMADR, chip);
 	__asm__ volatile("eieio");

 	tran = 0;
 	result = IIC_OK;
 	creg = 0;

 	while ( tran != cnt && (result == IIC_OK)) {
 		int  bc,j;

 		/* Control register =
 		   Normal transfer, 7-bits adressing, Transfer up to bc bytes, Normal start,
 		   Transfer is a sequence of transfers
 		*/
 		creg |= IIC_CNTL_PT;

 		bc = (cnt - tran) > 4 ? 4 :
 			cnt - tran;
 		creg |= (bc-1)<<4;
 		/* if the real cmd type is write continue trans*/
 		if ( (!cmd_type && (ptr == addr)) || ((tran+bc) != cnt) )
 			creg |= IIC_CNTL_CHT;

 		if (reading)
 			creg |= IIC_CNTL_READ;
 		else {
 			for(j=0; j<bc; j++) {
 				/* Set buffer */
 				out8(IIC_MDBUF,ptr[tran+j]);
 				__asm__ volatile("eieio");
 			}
 		}
 		out8(IIC_CNTL, creg );
 		__asm__ volatile("eieio");

 		/* Transfer is in progress
 		   we have to wait for upto 5 bytes of data
 		   1 byte chip address+r/w bit then bc bytes
 		   of data.
 		   udelay(10) is 1 bit time at 100khz
 		   Doubled for slop. 20 is too small.
 		*/
 		i=2*5*8;
 		do {
 			/* Get status */
 			status = in8(IIC_STS);
 			__asm__ volatile("eieio");
 			udelay (10);
 			i--;
 		} while ((status & IIC_STS_PT) && !(status & IIC_STS_ERR)
 			 && (i>0));

 		if (status & IIC_STS_ERR) {
 			result = IIC_NOK;
 			status = in8 (IIC_EXTSTS);
 			/* Lost arbitration? */
 			if (status & IIC_EXTSTS_LA)
 				result = IIC_NOK_LA;
 			/* Incomplete transfer? */
 			if (status & IIC_EXTSTS_ICT)
 				result = IIC_NOK_ICT;
 			/* Transfer aborted? */
 			if (status & IIC_EXTSTS_XFRA)
 				result = IIC_NOK_XFRA;
 		} else if ( status & IIC_STS_PT) {
 			result = IIC_NOK_TOUT;
 		}
 		/* Command is reading => get buffer */
 		if ((reading) && (result == IIC_OK)) {
 			/* Are there data in buffer */
 			if (status & IIC_STS_MDBS) {
 				/*
 				  even if we have data we have to wait 4OPB clocks
 				  for it to hit the front of the FIFO, after that
 				  we can just read. We should check XFCNT here and
 				  if the FIFO is full there is no need to wait.
 				*/
 				udelay (1);
 				for(j=0;j<bc;j++) {
 					ptr[tran+j] = in8(IIC_MDBUF);
 					__asm__ volatile("eieio");
 				}
 			} else
 				result = IIC_NOK_DATA;
 		}
 		creg = 0;
 		tran+=bc;
 		if( ptr == addr && tran == cnt ) {
 			ptr = data;
 			cnt = data_len;
 			tran = 0;
 			reading = cmd_type;
 			if( reading )
 				creg = IIC_CNTL_RPST;
 		}
 	}
 	return (result);
 }

 int i2c_probe (uchar chip)
 {
 	uchar buf[1];

 	buf[0] = 0;

 	/*
 	 * What is needed is to send the chip address and verify that the
 	 * address was <ACK>ed (i.e. there was a chip at that address which
 	 * drove the data line low).
 	 */
 	return(i2c_transfer (1, chip << 1, 0,0, buf, 1) != 0);
 }


 int i2c_read (uchar chip, uint addr, int alen, uchar * buffer, int len)
 {
 	uchar xaddr[4];
 	int ret;

 	if ( alen > 4 ) {
 		printf ("I2C read: addr len %d not supported\n", alen);
 		return 1;
 	}

 	if ( alen > 0 ) {
 		xaddr[0] = (addr >> 24) & 0xFF;
 		xaddr[1] = (addr >> 16) & 0xFF;
 		xaddr[2] = (addr >> 8) & 0xFF;
 		xaddr[3] = addr & 0xFF;
 	}


 #ifdef CFG_I2C_EEPROM_ADDR_OVERFLOW
 	/*
 	 * EEPROM chips that implement "address overflow" are ones
 	 * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
 	 * address and the extra bits end up in the "chip address"
 	 * bit slots. This makes a 24WC08 (1Kbyte) chip look like
 	 * four 256 byte chips.
 	 *
 	 * Note that we consider the length of the address field to
 	 * still be one byte because the extra address bits are
 	 * hidden in the chip address.
 	 */
 	if( alen > 0 )
 		chip |= ((addr >> (alen * 8)) & CFG_I2C_EEPROM_ADDR_OVERFLOW);
 #endif
 	if( (ret = i2c_transfer( 1, chip<<1, &xaddr[4-alen], alen, buffer, len )) != 0) {
 		printf( "I2c read: failed %d\n", ret);
 		return 1;
 	}
 	return 0;
 }

 int i2c_write (uchar chip, uint addr, int alen, uchar * buffer, int len)
 {
 	uchar xaddr[4];

 	if ( alen > 4 ) {
 		printf ("I2C write: addr len %d not supported\n", alen);
 		return 1;

 	}
 	if ( alen > 0 ) {
 		xaddr[0] = (addr >> 24) & 0xFF;
 		xaddr[1] = (addr >> 16) & 0xFF;
 		xaddr[2] = (addr >> 8) & 0xFF;
 		xaddr[3] = addr & 0xFF;
 	}

 #ifdef CFG_I2C_EEPROM_ADDR_OVERFLOW
 	/*
 	 * EEPROM chips that implement "address overflow" are ones
 	 * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
 	 * address and the extra bits end up in the "chip address"
 	 * bit slots. This makes a 24WC08 (1Kbyte) chip look like
 	 * four 256 byte chips.
 	 *
 	 * Note that we consider the length of the address field to
 	 * still be one byte because the extra address bits are
 	 * hidden in the chip address.
 	 */
 	if( alen > 0 )
 		chip |= ((addr >> (alen * 8)) & CFG_I2C_EEPROM_ADDR_OVERFLOW);
 #endif

 	return (i2c_transfer( 0, chip<<1, &xaddr[4-alen], alen, buffer, len ) != 0);
 }

 /*-----------------------------------------------------------------------
  * Read a register
  */
 uchar i2c_reg_read(uchar i2c_addr, uchar reg)
 {
 	char buf;

 	i2c_read(i2c_addr, reg, 1, &buf, 1);

 	return(buf);
 }

 /*-----------------------------------------------------------------------
  * Write a register
  */
 void i2c_reg_write(uchar i2c_addr, uchar reg, uchar val)
 {
 	i2c_write(i2c_addr, reg, 1, &val, 1);
 }
 #endif	/* CONFIG_HARD_I2C */
	/*****************************************************************************/
	/* I2C Bus interface initialisation and I2C Commands */
	/* for PPC405GP */
	/* Author : AS HARNOIS */
	/* Date : 13.Dec.00 */
	/*****************************************************************************/

	#include <common.h>
	#include <ppc4xx.h>
	#if defined(CONFIG_440)
	# include <440_i2c.h>
	#else
	# include <405gp_i2c.h>
	#endif
	#include <i2c.h>

	#ifdef CONFIG_HARD_I2C

	#define IIC_OK 0
	#define IIC_NOK 1
	#define IIC_NOK_LA 2 /* Lost arbitration */
	#define IIC_NOK_ICT 3 /* Incomplete transfer */
	#define IIC_NOK_XFRA 4 /* Transfer aborted */
	#define IIC_NOK_DATA 5 /* No data in buffer */
	#define IIC_NOK_TOUT 6 /* Transfer timeout */

	#define IIC_TIMEOUT 1 /* 1 seconde */


	static void _i2c_bus_reset (void)
	{
	int i, status;

	/* Reset status register */
	/* write 1 in SCMP and IRQA to clear these fields */
	out8 (IIC_STS, 0x0A);

	/* write 1 in IRQP IRQD LA ICT XFRA to clear these fields */
	out8 (IIC_EXTSTS, 0x8F);
	__asm__ volatile ("eieio");

	/*
	* Get current state, reset bus
	* only if no transfers are pending.
	*/
	i = 10;
	do {
	/* Get status */
	status = in8 (IIC_STS);
	udelay (500); /* 500us */
	i--;
	} while ((status & IIC_STS_PT) && (i > 0));
	/* Soft reset controller */
	status = in8 (IIC_XTCNTLSS);
	out8 (IIC_XTCNTLSS, (status \| IIC_XTCNTLSS_SRST));
	__asm__ volatile ("eieio");

	/* make sure where in initial state, data hi, clock hi */
	out8 (IIC_DIRECTCNTL, 0xC);
	for (i = 0; i < 10; i++) {
	if ((in8 (IIC_DIRECTCNTL) & 0x3) != 0x3) {
	/* clock until we get to known state */
	out8 (IIC_DIRECTCNTL, 0x8); /* clock lo */
	udelay (100); /* 100us */
	out8 (IIC_DIRECTCNTL, 0xC); /* clock hi */
	udelay (100); /* 100us */
	} else {
	break;
	}
	}
	/* send start condition */
	out8 (IIC_DIRECTCNTL, 0x4);
	udelay (1000); /* 1ms */
	/* send stop condition */
	out8 (IIC_DIRECTCNTL, 0xC);
	udelay (1000); /* 1ms */
	/* Unreset controller */
	out8 (IIC_XTCNTLSS, (status & ~IIC_XTCNTLSS_SRST));
	udelay (1000); /* 1ms */
	}

	void i2c_init (int speed, int slaveadd)
	{
	sys_info_t sysInfo;
	unsigned long freqOPB;
	int val, divisor;

	#ifdef CFG_I2C_INIT_BOARD
	/* call board specific i2c bus reset routine before accessing the */
	/* environment, which might be in a chip on that bus. For details */
	/* about this problem see doc/I2C_Edge_Conditions. */
	i2c_init_board();
	#endif

	/* Handle possible failed I2C state */
	/* FIXME: put this into i2c_init_board()? */
	_i2c_bus_reset ();

	/* clear lo master address */
	out8 (IIC_LMADR, 0);

	/* clear hi master address */
	out8 (IIC_HMADR, 0);

	/* clear lo slave address */
	out8 (IIC_LSADR, 0);

	/* clear hi slave address */
	out8 (IIC_HSADR, 0);

	/* Clock divide Register */
	/* get OPB frequency */
	get_sys_info (&sysInfo);
	freqOPB = sysInfo.freqPLB / sysInfo.pllOpbDiv;
	/* set divisor according to freqOPB */
	divisor = (freqOPB - 1) / 10000000;
	if (divisor == 0)
	divisor = 1;
	out8 (IIC_CLKDIV, divisor);

	/* no interrupts */
	out8 (IIC_INTRMSK, 0);

	/* clear transfer count */
	out8 (IIC_XFRCNT, 0);

	/* clear extended control & stat */
	/* write 1 in SRC SRS SWC SWS to clear these fields */
	out8 (IIC_XTCNTLSS, 0xF0);

	/* Mode Control Register
	Flush Slave/Master data buffer */
	out8 (IIC_MDCNTL, IIC_MDCNTL_FSDB \| IIC_MDCNTL_FMDB);
	__asm__ volatile ("eieio");


	val = in8(IIC_MDCNTL);
	__asm__ volatile ("eieio");

	/* Ignore General Call, slave transfers are ignored,
	disable interrupts, exit unknown bus state, enable hold
	SCL
	100kHz normaly or FastMode for 400kHz and above
	*/

	val \|= IIC_MDCNTL_EUBS\|IIC_MDCNTL_HSCL;
	if( speed >= 400000 ){
	val \|= IIC_MDCNTL_FSM;
	}
	out8 (IIC_MDCNTL, val);

	/* clear control reg */
	out8 (IIC_CNTL, 0x00);
	__asm__ volatile ("eieio");

	}

	/*
	This code tries to use the features of the 405GP i2c
	controller. It will transfer up to 4 bytes in one pass
	on the loop. It only does out8(lbz) to the buffer when it
	is possible to do out16(lhz) transfers.

	cmd_type is 0 for write 1 for read.

	addr_len can take any value from 0-255, it is only limited
	by the char, we could make it larger if needed. If it is
	0 we skip the address write cycle.

	Typical case is a Write of an addr followd by a Read. The
	IBM FAQ does not cover this. On the last byte of the write
	we don't set the creg CHT bit, and on the first bytes of the
	read we set the RPST bit.

	It does not support address only transfers, there must be
	a data part. If you want to write the address yourself, put
	it in the data pointer.

	It does not support transfer to/from address 0.

	It does not check XFRCNT.
	*/
	static
	int i2c_transfer(unsigned char cmd_type,
	unsigned char chip,
	unsigned char addr[],
	unsigned char addr_len,
	unsigned char data[],
	unsigned short data_len )
	{
	unsigned char* ptr;
	int reading;
	int tran,cnt;
	int result;
	int status;
	int i;
	uchar creg;

	if( data == 0 \|\| data_len == 0 ){
	/Don't support data transfer of no length or to address 0/
	printf( "i2c_transfer: bad call\n" );
	return IIC_NOK;
	}
	if( addr && addr_len ){
	ptr = addr;
	cnt = addr_len;
	reading = 0;
	}else{
	ptr = data;
	cnt = data_len;
	reading = cmd_type;
	}

	/Clear Stop Complete Bit/
	out8(IIC_STS,IIC_STS_SCMP);
	/* Check init */
	i=10;
	do {
	/* Get status */
	status = in8(IIC_STS);
	__asm__ volatile("eieio");
	i--;
	} while ((status & IIC_STS_PT) && (i>0));

	if (status & IIC_STS_PT) {
	result = IIC_NOK_TOUT;
	return(result);
	}
	/flush the Master/Slave Databuffers/
	out8(IIC_MDCNTL, ((in8(IIC_MDCNTL))\|IIC_MDCNTL_FMDB\|IIC_MDCNTL_FSDB));
	/need to wait 4 OPB clocks? code below should take that long/

	/* 7-bit adressing */
	out8(IIC_HMADR,0);
	out8(IIC_LMADR, chip);
	__asm__ volatile("eieio");

	tran = 0;
	result = IIC_OK;
	creg = 0;

	while ( tran != cnt && (result == IIC_OK)) {
	int bc,j;

	/* Control register =
	Normal transfer, 7-bits adressing, Transfer up to bc bytes, Normal start,
	Transfer is a sequence of transfers
	*/
	creg \|= IIC_CNTL_PT;

	bc = (cnt - tran) > 4 ? 4 :
	cnt - tran;
	creg \|= (bc-1)<<4;
	/* if the real cmd type is write continue trans*/
	if ( (!cmd_type && (ptr == addr)) \|\| ((tran+bc) != cnt) )
	creg \|= IIC_CNTL_CHT;

	if (reading)
	creg \|= IIC_CNTL_READ;
	else {
	for(j=0; j<bc; j++) {
	/* Set buffer */
	out8(IIC_MDBUF,ptr[tran+j]);
	__asm__ volatile("eieio");
	}
	}
	out8(IIC_CNTL, creg );
	__asm__ volatile("eieio");

	/* Transfer is in progress
	we have to wait for upto 5 bytes of data
	1 byte chip address+r/w bit then bc bytes
	of data.
	udelay(10) is 1 bit time at 100khz
	Doubled for slop. 20 is too small.
	*/
	i=258;
	do {
	/* Get status */
	status = in8(IIC_STS);
	__asm__ volatile("eieio");
	udelay (10);
	i--;
	} while ((status & IIC_STS_PT) && !(status & IIC_STS_ERR)
	&& (i>0));

	if (status & IIC_STS_ERR) {
	result = IIC_NOK;
	status = in8 (IIC_EXTSTS);
	/* Lost arbitration? */
	if (status & IIC_EXTSTS_LA)
	result = IIC_NOK_LA;
	/* Incomplete transfer? */
	if (status & IIC_EXTSTS_ICT)
	result = IIC_NOK_ICT;
	/* Transfer aborted? */
	if (status & IIC_EXTSTS_XFRA)
	result = IIC_NOK_XFRA;
	} else if ( status & IIC_STS_PT) {
	result = IIC_NOK_TOUT;
	}
	/* Command is reading => get buffer */
	if ((reading) && (result == IIC_OK)) {
	/* Are there data in buffer */
	if (status & IIC_STS_MDBS) {
	/*
	even if we have data we have to wait 4OPB clocks
	for it to hit the front of the FIFO, after that
	we can just read. We should check XFCNT here and
	if the FIFO is full there is no need to wait.
	*/
	udelay (1);
	for(j=0;j<bc;j++) {
	ptr[tran+j] = in8(IIC_MDBUF);
	__asm__ volatile("eieio");
	}
	} else
	result = IIC_NOK_DATA;
	}
	creg = 0;
	tran+=bc;
	if( ptr == addr && tran == cnt ) {
	ptr = data;
	cnt = data_len;
	tran = 0;
	reading = cmd_type;
	if( reading )
	creg = IIC_CNTL_RPST;
	}
	}
	return (result);
	}

	int i2c_probe (uchar chip)
	{
	uchar buf[1];

	buf[0] = 0;

	/*
	* What is needed is to send the chip address and verify that the
	* address was <ACK>ed (i.e. there was a chip at that address which
	* drove the data line low).
	*/
	return(i2c_transfer (1, chip << 1, 0,0, buf, 1) != 0);
	}


	int i2c_read (uchar chip, uint addr, int alen, uchar * buffer, int len)
	{
	uchar xaddr[4];
	int ret;

	if ( alen > 4 ) {
	printf ("I2C read: addr len %d not supported\n", alen);
	return 1;
	}

	if ( alen > 0 ) {
	xaddr[0] = (addr >> 24) & 0xFF;
	xaddr[1] = (addr >> 16) & 0xFF;
	xaddr[2] = (addr >> 8) & 0xFF;
	xaddr[3] = addr & 0xFF;
	}


	#ifdef CFG_I2C_EEPROM_ADDR_OVERFLOW
	/*
	* EEPROM chips that implement "address overflow" are ones
	* like Catalyst 24WC04/08/16 which has 9/10/11 bits of
	* address and the extra bits end up in the "chip address"
	* bit slots. This makes a 24WC08 (1Kbyte) chip look like
	* four 256 byte chips.
	*
	* Note that we consider the length of the address field to
	* still be one byte because the extra address bits are
	* hidden in the chip address.
	*/
	if( alen > 0 )
	chip \|= ((addr >> (alen * 8)) & CFG_I2C_EEPROM_ADDR_OVERFLOW);
	#endif
	if( (ret = i2c_transfer( 1, chip<<1, &xaddr[4-alen], alen, buffer, len )) != 0) {
	printf( "I2c read: failed %d\n", ret);
	return 1;
	}
	return 0;
	}

	int i2c_write (uchar chip, uint addr, int alen, uchar * buffer, int len)
	{
	uchar xaddr[4];

	if ( alen > 4 ) {
	printf ("I2C write: addr len %d not supported\n", alen);
	return 1;

	}
	if ( alen > 0 ) {
	xaddr[0] = (addr >> 24) & 0xFF;
	xaddr[1] = (addr >> 16) & 0xFF;
	xaddr[2] = (addr >> 8) & 0xFF;
	xaddr[3] = addr & 0xFF;
	}

	#ifdef CFG_I2C_EEPROM_ADDR_OVERFLOW
	/*
	* EEPROM chips that implement "address overflow" are ones
	* like Catalyst 24WC04/08/16 which has 9/10/11 bits of
	* address and the extra bits end up in the "chip address"
	* bit slots. This makes a 24WC08 (1Kbyte) chip look like
	* four 256 byte chips.
	*
	* Note that we consider the length of the address field to
	* still be one byte because the extra address bits are
	* hidden in the chip address.
	*/
	if( alen > 0 )
	chip \|= ((addr >> (alen * 8)) & CFG_I2C_EEPROM_ADDR_OVERFLOW);
	#endif

	return (i2c_transfer( 0, chip<<1, &xaddr[4-alen], alen, buffer, len ) != 0);
	}

	/*-----------------------------------------------------------------------
	* Read a register
	*/
	uchar i2c_reg_read(uchar i2c_addr, uchar reg)
	{
	char buf;

	i2c_read(i2c_addr, reg, 1, &buf, 1);

	return(buf);
	}

	/*-----------------------------------------------------------------------
	* Write a register
	*/
	void i2c_reg_write(uchar i2c_addr, uchar reg, uchar val)
	{
	i2c_write(i2c_addr, reg, 1, &val, 1);
	}
	#endif /* CONFIG_HARD_I2C */