drivers/i2c/designware_i2c.c - uboot/armada - Git at Google

 /*
  * (C) Copyright 2009
  * Vipin Kumar, ST Micoelectronics, vipin.kumar@st.com.
  *
  * 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 <asm/io.h>
 #include <asm/arch/hardware.h>
 #include "designware_i2c.h"

 #ifdef CONFIG_I2C_MULTI_BUS
 static unsigned int bus_initialized[CONFIG_SYS_I2C_BUS_MAX];
 static unsigned int current_bus = 0;
 #endif

 static struct i2c_regs *i2c_regs_p =
     (struct i2c_regs *)CONFIG_SYS_I2C_BASE;

 /*
  * set_speed - Set the i2c speed mode (standard, high, fast)
  * @i2c_spd:	required i2c speed mode
  *
  * Set the i2c speed mode (standard, high, fast)
  */
 static void set_speed(int i2c_spd)
 {
 	unsigned int cntl;
 	unsigned int hcnt, lcnt;
 	unsigned int enbl;

 	/* to set speed cltr must be disabled */
 	enbl = readl(&i2c_regs_p->ic_enable);
 	enbl &= ~IC_ENABLE_0B;
 	writel(enbl, &i2c_regs_p->ic_enable);

 	cntl = (readl(&i2c_regs_p->ic_con) & (~IC_CON_SPD_MSK));

 	switch (i2c_spd) {
 	case IC_SPEED_MODE_MAX:
 		cntl |= IC_CON_SPD_HS;
 		hcnt = (IC_CLK * MIN_HS_SCL_HIGHTIME) / NANO_TO_MICRO;
 		writel(hcnt, &i2c_regs_p->ic_hs_scl_hcnt);
 		lcnt = (IC_CLK * MIN_HS_SCL_LOWTIME) / NANO_TO_MICRO;
 		writel(lcnt, &i2c_regs_p->ic_hs_scl_lcnt);
 		break;

 	case IC_SPEED_MODE_STANDARD:
 		cntl |= IC_CON_SPD_SS;
 		hcnt = (IC_CLK * MIN_SS_SCL_HIGHTIME) / NANO_TO_MICRO;
 		writel(hcnt, &i2c_regs_p->ic_ss_scl_hcnt);
 		lcnt = (IC_CLK * MIN_SS_SCL_LOWTIME) / NANO_TO_MICRO;
 		writel(lcnt, &i2c_regs_p->ic_ss_scl_lcnt);
 		break;

 	case IC_SPEED_MODE_FAST:
 	default:
 		cntl |= IC_CON_SPD_FS;
 		hcnt = (IC_CLK * MIN_FS_SCL_HIGHTIME) / NANO_TO_MICRO;
 		writel(hcnt, &i2c_regs_p->ic_fs_scl_hcnt);
 		lcnt = (IC_CLK * MIN_FS_SCL_LOWTIME) / NANO_TO_MICRO;
 		writel(lcnt, &i2c_regs_p->ic_fs_scl_lcnt);
 		break;
 	}

 	writel(cntl, &i2c_regs_p->ic_con);

 	/* Enable back i2c now speed set */
 	enbl |= IC_ENABLE_0B;
 	writel(enbl, &i2c_regs_p->ic_enable);
 }

 /*
  * i2c_set_bus_speed - Set the i2c speed
  * @speed:	required i2c speed
  *
  * Set the i2c speed.
  */
 int i2c_set_bus_speed(int speed)
 {
 	if (speed >= I2C_MAX_SPEED)
 		set_speed(IC_SPEED_MODE_MAX);
 	else if (speed >= I2C_FAST_SPEED)
 		set_speed(IC_SPEED_MODE_FAST);
 	else
 		set_speed(IC_SPEED_MODE_STANDARD);

 	return 0;
 }

 /*
  * i2c_get_bus_speed - Gets the i2c speed
  *
  * Gets the i2c speed.
  */
 int i2c_get_bus_speed(void)
 {
 	u32 cntl;

 	cntl = (readl(&i2c_regs_p->ic_con) & IC_CON_SPD_MSK);

 	if (cntl == IC_CON_SPD_HS)
 		return I2C_MAX_SPEED;
 	else if (cntl == IC_CON_SPD_FS)
 		return I2C_FAST_SPEED;
 	else if (cntl == IC_CON_SPD_SS)
 		return I2C_STANDARD_SPEED;

 	return 0;
 }

 /*
  * i2c_init - Init function
  * @speed:	required i2c speed
  * @slaveadd:	slave address for the device
  *
  * Initialization function.
  */
 void i2c_init(int speed, int slaveadd)
 {
 	unsigned int enbl;

 	/* Disable i2c */
 	enbl = readl(&i2c_regs_p->ic_enable);
 	enbl &= ~IC_ENABLE_0B;
 	writel(enbl, &i2c_regs_p->ic_enable);

 	writel((IC_CON_SD | IC_CON_SPD_FS | IC_CON_MM), &i2c_regs_p->ic_con);
 	writel(IC_RX_TL, &i2c_regs_p->ic_rx_tl);
 	writel(IC_TX_TL, &i2c_regs_p->ic_tx_tl);
 	i2c_set_bus_speed(speed);
 	writel(IC_STOP_DET, &i2c_regs_p->ic_intr_mask);
 	writel(slaveadd, &i2c_regs_p->ic_sar);

 	/* Enable i2c */
 	enbl = readl(&i2c_regs_p->ic_enable);
 	enbl |= IC_ENABLE_0B;
 	writel(enbl, &i2c_regs_p->ic_enable);

 #ifdef CONFIG_I2C_MULTI_BUS
 	bus_initialized[current_bus] = 1;
 #endif
 }

 /*
  * i2c_setaddress - Sets the target slave address
  * @i2c_addr:	target i2c address
  *
  * Sets the target slave address.
  */
 static void i2c_setaddress(unsigned int i2c_addr)
 {
 	writel(i2c_addr, &i2c_regs_p->ic_tar);
 }

 /*
  * i2c_flush_rxfifo - Flushes the i2c RX FIFO
  *
  * Flushes the i2c RX FIFO
  */
 static void i2c_flush_rxfifo(void)
 {
 	while (readl(&i2c_regs_p->ic_status) & IC_STATUS_RFNE)
 		readl(&i2c_regs_p->ic_cmd_data);
 }

 /*
  * i2c_wait_for_bb - Waits for bus busy
  *
  * Waits for bus busy
  */
 static int i2c_wait_for_bb(void)
 {
 	unsigned long start_time_bb = get_timer(0);

 	while ((readl(&i2c_regs_p->ic_status) & IC_STATUS_MA) ||
 	       !(readl(&i2c_regs_p->ic_status) & IC_STATUS_TFE)) {

 		/* Evaluate timeout */
 		if (get_timer(start_time_bb) > (unsigned long)(I2C_BYTE_TO_BB))
 			return 1;
 	}

 	return 0;
 }

 /* check parameters for i2c_read and i2c_write */
 static int check_params(uint addr, int alen, uchar *buffer, int len)
 {
 	if (buffer == NULL) {
 		printf("Buffer is invalid\n");
 		return 1;
 	}

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

 	if (addr + len > 256) {
 		printf("address out of range\n");
 		return 1;
 	}

 	return 0;
 }

 static int i2c_xfer_init(uchar chip, uint addr)
 {
 	if (i2c_wait_for_bb())
 		return 1;

 	i2c_setaddress(chip);
 	writel(addr, &i2c_regs_p->ic_cmd_data);

 	return 0;
 }

 static int i2c_xfer_finish(void)
 {
 	ulong start_stop_det = get_timer(0);

 	while (1) {
 		if ((readl(&i2c_regs_p->ic_raw_intr_stat) & IC_STOP_DET)) {
 			readl(&i2c_regs_p->ic_clr_stop_det);
 			break;
 		} else if (get_timer(start_stop_det) > I2C_STOPDET_TO) {
 			break;
 		}
 	}

 	if (i2c_wait_for_bb()) {
 		printf("Timed out waiting for bus\n");
 		return 1;
 	}

 	i2c_flush_rxfifo();

 	/* Wait for read/write operation to complete on actual memory */
 	udelay(10000);

 	return 0;
 }

 /*
  * i2c_read - Read from i2c memory
  * @chip:	target i2c address
  * @addr:	address to read from
  * @alen:
  * @buffer:	buffer for read data
  * @len:	no of bytes to be read
  *
  * Read from i2c memory.
  */
 int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
 {
 	unsigned long start_time_rx;

 	if (check_params(addr, alen, buffer, len))
 		return 1;

 	if (i2c_xfer_init(chip, addr))
 		return 1;

 	start_time_rx = get_timer(0);
 	while (len) {
 		if (len == 1)
 			writel(IC_CMD | IC_STOP, &i2c_regs_p->ic_cmd_data);
 		else
 			writel(IC_CMD, &i2c_regs_p->ic_cmd_data);

 		if (readl(&i2c_regs_p->ic_status) & IC_STATUS_RFNE) {
 			*buffer++ = (uchar)readl(&i2c_regs_p->ic_cmd_data);
 			len--;
 			start_time_rx = get_timer(0);

 		} else if (get_timer(start_time_rx) > I2C_BYTE_TO) {
 				return 1;
 		}
 	}

 	return i2c_xfer_finish();
 }

 /*
  * i2c_write - Write to i2c memory
  * @chip:	target i2c address
  * @addr:	address to read from
  * @alen:
  * @buffer:	buffer for read data
  * @len:	no of bytes to be read
  *
  * Write to i2c memory.
  */
 int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
 {
 	int nb = len;
 	unsigned long start_time_tx;

 	if (check_params(addr, alen, buffer, len))
 		return 1;

 	if (i2c_xfer_init(chip, addr))
 		return 1;

 	start_time_tx = get_timer(0);
 	while (len) {
 		if (readl(&i2c_regs_p->ic_status) & IC_STATUS_TFNF) {
 			if (--len == 0)
 				writel(*buffer | IC_STOP, &i2c_regs_p->ic_cmd_data);
 			else
 				writel(*buffer, &i2c_regs_p->ic_cmd_data);
 			buffer++;
 			start_time_tx = get_timer(0);

 		} else if (get_timer(start_time_tx) > (nb * I2C_BYTE_TO)) {
 				printf("Timed out. i2c write Failed\n");
 				return 1;
 		}
 	}

 	return i2c_xfer_finish();
 }

 /*
  * i2c_probe - Probe the i2c chip
  */
 int i2c_probe(uchar chip)
 {
 	u32 tmp;
 	int ret;

 	/*
 	 * Try to read the first location of the chip.
 	 */
 	ret = i2c_read(chip, 0, 1, (uchar *)&tmp, 1);
 	if (ret)
 		i2c_init(CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);

 	return ret;
 }

 #ifdef CONFIG_I2C_MULTI_BUS
 int i2c_set_bus_num(unsigned int bus)
 {
 	switch (bus) {
 	case 0:
 		i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE;
 		break;
 #ifdef CONFIG_SYS_I2C_BASE1
 	case 1:
 		i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE1;
 		break;
 #endif
 #ifdef CONFIG_SYS_I2C_BASE2
 	case 2:
 		i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE2;
 		break;
 #endif
 #ifdef CONFIG_SYS_I2C_BASE3
 	case 3:
 		i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE3;
 		break;
 #endif
 #ifdef CONFIG_SYS_I2C_BASE4
 	case 4:
 		i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE4;
 		break;
 #endif
 #ifdef CONFIG_SYS_I2C_BASE5
 	case 5:
 		i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE5;
 		break;
 #endif
 #ifdef CONFIG_SYS_I2C_BASE6
 	case 6:
 		i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE6;
 		break;
 #endif
 #ifdef CONFIG_SYS_I2C_BASE7
 	case 7:
 		i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE7;
 		break;
 #endif
 #ifdef CONFIG_SYS_I2C_BASE8
 	case 8:
 		i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE8;
 		break;
 #endif
 #ifdef CONFIG_SYS_I2C_BASE9
 	case 9:
 		i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE9;
 		break;
 #endif
 	default:
 		printf("Bad bus: %d\n", bus);
 		return -1;
 	}

 	current_bus = bus;

 	if (!bus_initialized[current_bus])
 		i2c_init(CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);

 	return 0;
 }

 int i2c_get_bus_num(void)
 {
 	return current_bus;
 }
 #endif
	/*
	* (C) Copyright 2009
	* Vipin Kumar, ST Micoelectronics, vipin.kumar@st.com.
	*
	* 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 <asm/io.h>
	#include <asm/arch/hardware.h>
	#include "designware_i2c.h"

	#ifdef CONFIG_I2C_MULTI_BUS
	static unsigned int bus_initialized[CONFIG_SYS_I2C_BUS_MAX];
	static unsigned int current_bus = 0;
	#endif

	static struct i2c_regs *i2c_regs_p =
	(struct i2c_regs *)CONFIG_SYS_I2C_BASE;

	/*
	* set_speed - Set the i2c speed mode (standard, high, fast)
	* @i2c_spd: required i2c speed mode
	*
	* Set the i2c speed mode (standard, high, fast)
	*/
	static void set_speed(int i2c_spd)
	{
	unsigned int cntl;
	unsigned int hcnt, lcnt;
	unsigned int enbl;

	/* to set speed cltr must be disabled */
	enbl = readl(&i2c_regs_p->ic_enable);
	enbl &= ~IC_ENABLE_0B;
	writel(enbl, &i2c_regs_p->ic_enable);

	cntl = (readl(&i2c_regs_p->ic_con) & (~IC_CON_SPD_MSK));

	switch (i2c_spd) {
	case IC_SPEED_MODE_MAX:
	cntl \|= IC_CON_SPD_HS;
	hcnt = (IC_CLK * MIN_HS_SCL_HIGHTIME) / NANO_TO_MICRO;
	writel(hcnt, &i2c_regs_p->ic_hs_scl_hcnt);
	lcnt = (IC_CLK * MIN_HS_SCL_LOWTIME) / NANO_TO_MICRO;
	writel(lcnt, &i2c_regs_p->ic_hs_scl_lcnt);
	break;

	case IC_SPEED_MODE_STANDARD:
	cntl \|= IC_CON_SPD_SS;
	hcnt = (IC_CLK * MIN_SS_SCL_HIGHTIME) / NANO_TO_MICRO;
	writel(hcnt, &i2c_regs_p->ic_ss_scl_hcnt);
	lcnt = (IC_CLK * MIN_SS_SCL_LOWTIME) / NANO_TO_MICRO;
	writel(lcnt, &i2c_regs_p->ic_ss_scl_lcnt);
	break;

	case IC_SPEED_MODE_FAST:
	default:
	cntl \|= IC_CON_SPD_FS;
	hcnt = (IC_CLK * MIN_FS_SCL_HIGHTIME) / NANO_TO_MICRO;
	writel(hcnt, &i2c_regs_p->ic_fs_scl_hcnt);
	lcnt = (IC_CLK * MIN_FS_SCL_LOWTIME) / NANO_TO_MICRO;
	writel(lcnt, &i2c_regs_p->ic_fs_scl_lcnt);
	break;
	}

	writel(cntl, &i2c_regs_p->ic_con);

	/* Enable back i2c now speed set */
	enbl \|= IC_ENABLE_0B;
	writel(enbl, &i2c_regs_p->ic_enable);
	}

	/*
	* i2c_set_bus_speed - Set the i2c speed
	* @speed: required i2c speed
	*
	* Set the i2c speed.
	*/
	int i2c_set_bus_speed(int speed)
	{
	if (speed >= I2C_MAX_SPEED)
	set_speed(IC_SPEED_MODE_MAX);
	else if (speed >= I2C_FAST_SPEED)
	set_speed(IC_SPEED_MODE_FAST);
	else
	set_speed(IC_SPEED_MODE_STANDARD);

	return 0;
	}

	/*
	* i2c_get_bus_speed - Gets the i2c speed
	*
	* Gets the i2c speed.
	*/
	int i2c_get_bus_speed(void)
	{
	u32 cntl;

	cntl = (readl(&i2c_regs_p->ic_con) & IC_CON_SPD_MSK);

	if (cntl == IC_CON_SPD_HS)
	return I2C_MAX_SPEED;
	else if (cntl == IC_CON_SPD_FS)
	return I2C_FAST_SPEED;
	else if (cntl == IC_CON_SPD_SS)
	return I2C_STANDARD_SPEED;

	return 0;
	}

	/*
	* i2c_init - Init function
	* @speed: required i2c speed
	* @slaveadd: slave address for the device
	*
	* Initialization function.
	*/
	void i2c_init(int speed, int slaveadd)
	{
	unsigned int enbl;

	/* Disable i2c */
	enbl = readl(&i2c_regs_p->ic_enable);
	enbl &= ~IC_ENABLE_0B;
	writel(enbl, &i2c_regs_p->ic_enable);

	writel((IC_CON_SD \| IC_CON_SPD_FS \| IC_CON_MM), &i2c_regs_p->ic_con);
	writel(IC_RX_TL, &i2c_regs_p->ic_rx_tl);
	writel(IC_TX_TL, &i2c_regs_p->ic_tx_tl);
	i2c_set_bus_speed(speed);
	writel(IC_STOP_DET, &i2c_regs_p->ic_intr_mask);
	writel(slaveadd, &i2c_regs_p->ic_sar);

	/* Enable i2c */
	enbl = readl(&i2c_regs_p->ic_enable);
	enbl \|= IC_ENABLE_0B;
	writel(enbl, &i2c_regs_p->ic_enable);

	#ifdef CONFIG_I2C_MULTI_BUS
	bus_initialized[current_bus] = 1;
	#endif
	}

	/*
	* i2c_setaddress - Sets the target slave address
	* @i2c_addr: target i2c address
	*
	* Sets the target slave address.
	*/
	static void i2c_setaddress(unsigned int i2c_addr)
	{
	writel(i2c_addr, &i2c_regs_p->ic_tar);
	}

	/*
	* i2c_flush_rxfifo - Flushes the i2c RX FIFO
	*
	* Flushes the i2c RX FIFO
	*/
	static void i2c_flush_rxfifo(void)
	{
	while (readl(&i2c_regs_p->ic_status) & IC_STATUS_RFNE)
	readl(&i2c_regs_p->ic_cmd_data);
	}

	/*
	* i2c_wait_for_bb - Waits for bus busy
	*
	* Waits for bus busy
	*/
	static int i2c_wait_for_bb(void)
	{
	unsigned long start_time_bb = get_timer(0);

	while ((readl(&i2c_regs_p->ic_status) & IC_STATUS_MA) \|\|
	!(readl(&i2c_regs_p->ic_status) & IC_STATUS_TFE)) {

	/* Evaluate timeout */
	if (get_timer(start_time_bb) > (unsigned long)(I2C_BYTE_TO_BB))
	return 1;
	}

	return 0;
	}

	/* check parameters for i2c_read and i2c_write */
	static int check_params(uint addr, int alen, uchar *buffer, int len)
	{
	if (buffer == NULL) {
	printf("Buffer is invalid\n");
	return 1;
	}

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

	if (addr + len > 256) {
	printf("address out of range\n");
	return 1;
	}

	return 0;
	}

	static int i2c_xfer_init(uchar chip, uint addr)
	{
	if (i2c_wait_for_bb())
	return 1;

	i2c_setaddress(chip);
	writel(addr, &i2c_regs_p->ic_cmd_data);

	return 0;
	}

	static int i2c_xfer_finish(void)
	{
	ulong start_stop_det = get_timer(0);

	while (1) {
	if ((readl(&i2c_regs_p->ic_raw_intr_stat) & IC_STOP_DET)) {
	readl(&i2c_regs_p->ic_clr_stop_det);
	break;
	} else if (get_timer(start_stop_det) > I2C_STOPDET_TO) {
	break;
	}
	}

	if (i2c_wait_for_bb()) {
	printf("Timed out waiting for bus\n");
	return 1;
	}

	i2c_flush_rxfifo();

	/* Wait for read/write operation to complete on actual memory */
	udelay(10000);

	return 0;
	}

	/*
	* i2c_read - Read from i2c memory
	* @chip: target i2c address
	* @addr: address to read from
	* @alen:
	* @buffer: buffer for read data
	* @len: no of bytes to be read
	*
	* Read from i2c memory.
	*/
	int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
	{
	unsigned long start_time_rx;

	if (check_params(addr, alen, buffer, len))
	return 1;

	if (i2c_xfer_init(chip, addr))
	return 1;

	start_time_rx = get_timer(0);
	while (len) {
	if (len == 1)
	writel(IC_CMD \| IC_STOP, &i2c_regs_p->ic_cmd_data);
	else
	writel(IC_CMD, &i2c_regs_p->ic_cmd_data);

	if (readl(&i2c_regs_p->ic_status) & IC_STATUS_RFNE) {
	*buffer++ = (uchar)readl(&i2c_regs_p->ic_cmd_data);
	len--;
	start_time_rx = get_timer(0);

	} else if (get_timer(start_time_rx) > I2C_BYTE_TO) {
	return 1;
	}
	}

	return i2c_xfer_finish();
	}

	/*
	* i2c_write - Write to i2c memory
	* @chip: target i2c address
	* @addr: address to read from
	* @alen:
	* @buffer: buffer for read data
	* @len: no of bytes to be read
	*
	* Write to i2c memory.
	*/
	int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
	{
	int nb = len;
	unsigned long start_time_tx;

	if (check_params(addr, alen, buffer, len))
	return 1;

	if (i2c_xfer_init(chip, addr))
	return 1;

	start_time_tx = get_timer(0);
	while (len) {
	if (readl(&i2c_regs_p->ic_status) & IC_STATUS_TFNF) {
	if (--len == 0)
	writel(*buffer \| IC_STOP, &i2c_regs_p->ic_cmd_data);
	else
	writel(*buffer, &i2c_regs_p->ic_cmd_data);
	buffer++;
	start_time_tx = get_timer(0);

	} else if (get_timer(start_time_tx) > (nb * I2C_BYTE_TO)) {
	printf("Timed out. i2c write Failed\n");
	return 1;
	}
	}

	return i2c_xfer_finish();
	}

	/*
	* i2c_probe - Probe the i2c chip
	*/
	int i2c_probe(uchar chip)
	{
	u32 tmp;
	int ret;

	/*
	* Try to read the first location of the chip.
	*/
	ret = i2c_read(chip, 0, 1, (uchar *)&tmp, 1);
	if (ret)
	i2c_init(CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);

	return ret;
	}

	#ifdef CONFIG_I2C_MULTI_BUS
	int i2c_set_bus_num(unsigned int bus)
	{
	switch (bus) {
	case 0:
	i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE;
	break;
	#ifdef CONFIG_SYS_I2C_BASE1
	case 1:
	i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE1;
	break;
	#endif
	#ifdef CONFIG_SYS_I2C_BASE2
	case 2:
	i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE2;
	break;
	#endif
	#ifdef CONFIG_SYS_I2C_BASE3
	case 3:
	i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE3;
	break;
	#endif
	#ifdef CONFIG_SYS_I2C_BASE4
	case 4:
	i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE4;
	break;
	#endif
	#ifdef CONFIG_SYS_I2C_BASE5
	case 5:
	i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE5;
	break;
	#endif
	#ifdef CONFIG_SYS_I2C_BASE6
	case 6:
	i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE6;
	break;
	#endif
	#ifdef CONFIG_SYS_I2C_BASE7
	case 7:
	i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE7;
	break;
	#endif
	#ifdef CONFIG_SYS_I2C_BASE8
	case 8:
	i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE8;
	break;
	#endif
	#ifdef CONFIG_SYS_I2C_BASE9
	case 9:
	i2c_regs_p = (void *)CONFIG_SYS_I2C_BASE9;
	break;
	#endif
	default:
	printf("Bad bus: %d\n", bus);
	return -1;
	}

	current_bus = bus;

	if (!bus_initialized[current_bus])
	i2c_init(CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);

	return 0;
	}

	int i2c_get_bus_num(void)
	{
	return current_bus;
	}
	#endif