i2c.c

来自「U-boot源码 ARM7启动代码」· C语言 代码 · 共 477 行

/*
 * (C) Copyright 2007
 * Stefan Roese, DENX Software Engineering, [e-mail].
 *
 * based on work by Anne Sophie Harnois <[e-mail]>
 *
 * (C) Copyright 2001
 * Bill Hunter,  Wave 7 Optics, [e-mail]
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * 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 <common.h>
#include <ppc4xx.h>
#include <4xx_i2c.h>
#include <i2c.h>
#include <asm-ppc/io.h>

#ifdef CONFIG_HARD_I2C

DECLARE_GLOBAL_DATA_PTR;

#if defined(CONFIG_I2C_MULTI_BUS)
/* Initialize the bus pointer to whatever one the SPD EEPROM is on.
 * Default is bus 0.  This is necessary because the DDR initialization
 * runs from ROM, and we can't switch buses because we can't modify
 * the global variables.
 */
#ifdef CFG_SPD_BUS_NUM
static unsigned int i2c_bus_num __attribute__ ((section ("data"))) = CFG_SPD_BUS_NUM;
#else
static unsigned int i2c_bus_num __attribute__ ((section ("data"))) = 0;
#endif
#endif /* CONFIG_I2C_MULTI_BUS */

static void _i2c_bus_reset(void)
{
	int i;
	u8 dc;

	/* Reset status register */
	/* write 1 in SCMP and IRQA to clear these fields */
	out_8((u8 *)IIC_STS, 0x0A);

	/* write 1 in IRQP IRQD LA ICT XFRA to clear these fields */
	out_8((u8 *)IIC_EXTSTS, 0x8F);

    	/* Place chip in the reset state */
	out_8((u8 *)IIC_XTCNTLSS, IIC_XTCNTLSS_SRST);

	/* Check if bus is free */
	dc = in_8((u8 *)IIC_DIRECTCNTL);
	if (!DIRCTNL_FREE(dc)){
		/* Try to set bus free state */
		out_8((u8 *)IIC_DIRECTCNTL, IIC_DIRCNTL_SDAC | IIC_DIRCNTL_SCC);

		/* Wait until we regain bus control */
		for (i = 0; i < 100; ++i) {
			dc = in_8((u8 *)IIC_DIRECTCNTL);
			if (DIRCTNL_FREE(dc))
				break;

			/* Toggle SCL line */
			dc ^= IIC_DIRCNTL_SCC;
			out_8((u8 *)IIC_DIRECTCNTL, dc);
			udelay(10);
			dc ^= IIC_DIRCNTL_SCC;
			out_8((u8 *)IIC_DIRECTCNTL, dc);
		}
	}

	/* Remove reset */
	out_8((u8 *)IIC_XTCNTLSS, 0);
}

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

#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

	for (bus = 0; bus < CFG_MAX_I2C_BUS; bus++) {
		I2C_SET_BUS(bus);

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

		/* clear lo master address */
		out_8((u8 *)IIC_LMADR, 0);

		/* clear hi master address */
		out_8((u8 *)IIC_HMADR, 0);

		/* clear lo slave address */
		out_8((u8 *)IIC_LSADR, 0);

		/* clear hi slave address */
		out_8((u8 *)IIC_HSADR, 0);

		/* Clock divide Register */
		/* get OPB frequency */
		freqOPB = get_OPB_freq();
		/* set divisor according to freqOPB */
		divisor = (freqOPB - 1) / 10000000;
		if (divisor == 0)
			divisor = 1;
		out_8((u8 *)IIC_CLKDIV, divisor);

		/* no interrupts */
		out_8((u8 *)IIC_INTRMSK, 0);

		/* clear transfer count */
		out_8((u8 *)IIC_XFRCNT, 0);

		/* clear extended control & stat */
		/* write 1 in SRC SRS SWC SWS to clear these fields */
		out_8((u8 *)IIC_XTCNTLSS, 0xF0);

		/* Mode Control Register
		   Flush Slave/Master data buffer */
		out_8((u8 *)IIC_MDCNTL, IIC_MDCNTL_FSDB | IIC_MDCNTL_FMDB);

		val = in_8((u8 *)IIC_MDCNTL);

		/* 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;
		out_8((u8 *)IIC_MDCNTL, val);

		/* clear control reg */
		out_8((u8 *)IIC_CNTL, 0x00);
	}

	/* set to SPD bus as default bus upon powerup */
	I2C_SET_BUS(CFG_SPD_BUS_NUM);
}

/*
 * 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 out_8((u8 *)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 */
	out_8((u8 *)IIC_STS, IIC_STS_SCMP);
	/* Check init */
	i = 10;
	do {
		/* Get status */
		status = in_8((u8 *)IIC_STS);
		i--;
	} while ((status & IIC_STS_PT) && (i > 0));

	if (status & IIC_STS_PT) {
		result = IIC_NOK_TOUT;
		return(result);
	}
	/* flush the Master/Slave Databuffers */
	out_8((u8 *)IIC_MDCNTL, ((in_8((u8 *)IIC_MDCNTL))|IIC_MDCNTL_FMDB|IIC_MDCNTL_FSDB));
	/* need to wait 4 OPB clocks? code below should take that long */

	/* 7-bit adressing */
	out_8((u8 *)IIC_HMADR, 0);
	out_8((u8 *)IIC_LMADR, chip);

	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 */
				out_8((u8 *)IIC_MDBUF, ptr[tran+j]);
		out_8((u8 *)IIC_CNTL, creg);

		/* 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 = in_8((u8 *)IIC_STS);
			udelay(10);
			i--;
		} while ((status & IIC_STS_PT) && !(status & IIC_STS_ERR) && (i > 0));

		if (status & IIC_STS_ERR) {
			result = IIC_NOK;
			status = in_8((u8 *)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] = in_8((u8 *)IIC_MDBUF);
			} 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) {
		if (gd->have_console)
			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)
{
	uchar 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);
}

#if defined(CONFIG_I2C_MULTI_BUS)
/*
 * Functions for multiple I2C bus handling
 */
unsigned int i2c_get_bus_num(void)
{
	return i2c_bus_num;
}

int i2c_set_bus_num(unsigned int bus)
{
	if (bus >= CFG_MAX_I2C_BUS)
		return -1;

	i2c_bus_num = bus;

	return 0;
}
#endif	/* CONFIG_I2C_MULTI_BUS */

/* TODO: add 100/400k switching */
unsigned int i2c_get_bus_speed(void)
{
	return CFG_I2C_SPEED;
}

int i2c_set_bus_speed(unsigned int speed)
{
	if (speed != CFG_I2C_SPEED)
		return -1;

	return 0;
}
#endif	/* CONFIG_HARD_I2C */