drivers/i2c/zynq_i2c.c - u-boot - Git at Google

 /*
  * Driver for the Zynq-7000 PS I2C controller
  * IP from Cadence (ID T-CS-PE-0007-100, Version R1p10f2)
  *
  * Author: Joe Hershberger <joe.hershberger@ni.com>
  * Copyright (c) 2012 Joe Hershberger.
  *
  * Copyright (c) 2012-2013 Xilinx, Michal Simek
  *
  * SPDX-License-Identifier:	GPL-2.0+
  */

 #include <common.h>
 #include <asm/io.h>
 #include <i2c.h>
 #include <asm/errno.h>
 #include <asm/arch/hardware.h>

 /* i2c register set */
 struct zynq_i2c_registers {
 	u32 control;
 	u32 status;
 	u32 address;
 	u32 data;
 	u32 interrupt_status;
 	u32 transfer_size;
 	u32 slave_mon_pause;
 	u32 time_out;
 	u32 interrupt_mask;
 	u32 interrupt_enable;
 	u32 interrupt_disable;
 };

 /* Control register fields */
 #define ZYNQ_I2C_CONTROL_RW		0x00000001
 #define ZYNQ_I2C_CONTROL_MS		0x00000002
 #define ZYNQ_I2C_CONTROL_NEA		0x00000004
 #define ZYNQ_I2C_CONTROL_ACKEN		0x00000008
 #define ZYNQ_I2C_CONTROL_HOLD		0x00000010
 #define ZYNQ_I2C_CONTROL_SLVMON		0x00000020
 #define ZYNQ_I2C_CONTROL_CLR_FIFO	0x00000040
 #define ZYNQ_I2C_CONTROL_DIV_B_SHIFT	8
 #define ZYNQ_I2C_CONTROL_DIV_B_MASK	0x00003F00
 #define ZYNQ_I2C_CONTROL_DIV_A_SHIFT	14
 #define ZYNQ_I2C_CONTROL_DIV_A_MASK	0x0000C000

 /* Status register values */
 #define ZYNQ_I2C_STATUS_RXDV	0x00000020
 #define ZYNQ_I2C_STATUS_TXDV	0x00000040
 #define ZYNQ_I2C_STATUS_RXOVF	0x00000080
 #define ZYNQ_I2C_STATUS_BA	0x00000100

 /* Interrupt register fields */
 #define ZYNQ_I2C_INTERRUPT_COMP		0x00000001
 #define ZYNQ_I2C_INTERRUPT_DATA		0x00000002
 #define ZYNQ_I2C_INTERRUPT_NACK		0x00000004
 #define ZYNQ_I2C_INTERRUPT_TO		0x00000008
 #define ZYNQ_I2C_INTERRUPT_SLVRDY	0x00000010
 #define ZYNQ_I2C_INTERRUPT_RXOVF	0x00000020
 #define ZYNQ_I2C_INTERRUPT_TXOVF	0x00000040
 #define ZYNQ_I2C_INTERRUPT_RXUNF	0x00000080
 #define ZYNQ_I2C_INTERRUPT_ARBLOST	0x00000200

 #define ZYNQ_I2C_FIFO_DEPTH		16
 #define ZYNQ_I2C_TRANSFERT_SIZE_MAX	255 /* Controller transfer limit */

 static struct zynq_i2c_registers *i2c_select(struct i2c_adapter *adap)
 {
 	return adap->hwadapnr ?
 		/* Zynq PS I2C1 */
 		(struct zynq_i2c_registers *)ZYNQ_I2C_BASEADDR1 :
 		/* Zynq PS I2C0 */
 		(struct zynq_i2c_registers *)ZYNQ_I2C_BASEADDR0;
 }

 /* I2C init called by cmd_i2c when doing 'i2c reset'. */
 static void zynq_i2c_init(struct i2c_adapter *adap, int requested_speed,
 			  int slaveadd)
 {
 	struct zynq_i2c_registers *zynq_i2c = i2c_select(adap);

 	/* 111MHz / ( (3 * 17) * 22 ) = ~100KHz */
 	writel((16 << ZYNQ_I2C_CONTROL_DIV_B_SHIFT) |
 		(2 << ZYNQ_I2C_CONTROL_DIV_A_SHIFT), &zynq_i2c->control);

 	/* Enable master mode, ack, and 7-bit addressing */
 	setbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_MS |
 		ZYNQ_I2C_CONTROL_ACKEN | ZYNQ_I2C_CONTROL_NEA);
 }

 #ifdef DEBUG
 static void zynq_i2c_debug_status(struct zynq_i2c_registers *zynq_i2c)
 {
 	int int_status;
 	int status;
 	int_status = readl(&zynq_i2c->interrupt_status);

 	status = readl(&zynq_i2c->status);
 	if (int_status || status) {
 		debug("Status: ");
 		if (int_status & ZYNQ_I2C_INTERRUPT_COMP)
 			debug("COMP ");
 		if (int_status & ZYNQ_I2C_INTERRUPT_DATA)
 			debug("DATA ");
 		if (int_status & ZYNQ_I2C_INTERRUPT_NACK)
 			debug("NACK ");
 		if (int_status & ZYNQ_I2C_INTERRUPT_TO)
 			debug("TO ");
 		if (int_status & ZYNQ_I2C_INTERRUPT_SLVRDY)
 			debug("SLVRDY ");
 		if (int_status & ZYNQ_I2C_INTERRUPT_RXOVF)
 			debug("RXOVF ");
 		if (int_status & ZYNQ_I2C_INTERRUPT_TXOVF)
 			debug("TXOVF ");
 		if (int_status & ZYNQ_I2C_INTERRUPT_RXUNF)
 			debug("RXUNF ");
 		if (int_status & ZYNQ_I2C_INTERRUPT_ARBLOST)
 			debug("ARBLOST ");
 		if (status & ZYNQ_I2C_STATUS_RXDV)
 			debug("RXDV ");
 		if (status & ZYNQ_I2C_STATUS_TXDV)
 			debug("TXDV ");
 		if (status & ZYNQ_I2C_STATUS_RXOVF)
 			debug("RXOVF ");
 		if (status & ZYNQ_I2C_STATUS_BA)
 			debug("BA ");
 		debug("TS%d ", readl(&zynq_i2c->transfer_size));
 		debug("\n");
 	}
 }
 #endif

 /* Wait for an interrupt */
 static u32 zynq_i2c_wait(struct zynq_i2c_registers *zynq_i2c, u32 mask)
 {
 	int timeout, int_status;

 	for (timeout = 0; timeout < 100; timeout++) {
 		udelay(100);
 		int_status = readl(&zynq_i2c->interrupt_status);
 		if (int_status & mask)
 			break;
 	}
 #ifdef DEBUG
 	zynq_i2c_debug_status(zynq_i2c);
 #endif
 	/* Clear interrupt status flags */
 	writel(int_status & mask, &zynq_i2c->interrupt_status);

 	return int_status & mask;
 }

 /*
  * I2C probe called by cmd_i2c when doing 'i2c probe'.
  * Begin read, nak data byte, end.
  */
 static int zynq_i2c_probe(struct i2c_adapter *adap, u8 dev)
 {
 	struct zynq_i2c_registers *zynq_i2c = i2c_select(adap);

 	/* Attempt to read a byte */
 	setbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_CLR_FIFO |
 		ZYNQ_I2C_CONTROL_RW);
 	clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_HOLD);
 	writel(0xFF, &zynq_i2c->interrupt_status);
 	writel(dev, &zynq_i2c->address);
 	writel(1, &zynq_i2c->transfer_size);

 	return (zynq_i2c_wait(zynq_i2c, ZYNQ_I2C_INTERRUPT_COMP |
 		ZYNQ_I2C_INTERRUPT_NACK) &
 		ZYNQ_I2C_INTERRUPT_COMP) ? 0 : -ETIMEDOUT;
 }

 /*
  * I2C read called by cmd_i2c when doing 'i2c read' and by cmd_eeprom.c
  * Begin write, send address byte(s), begin read, receive data bytes, end.
  */
 static int zynq_i2c_read(struct i2c_adapter *adap, u8 dev, uint addr,
 			 int alen, u8 *data, int length)
 {
 	u32 status;
 	u32 i = 0;
 	u8 *cur_data = data;
 	struct zynq_i2c_registers *zynq_i2c = i2c_select(adap);

 	/* Check the hardware can handle the requested bytes */
 	if ((length < 0) || (length > ZYNQ_I2C_TRANSFERT_SIZE_MAX))
 		return -EINVAL;

 	/* Write the register address */
 	setbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_CLR_FIFO |
 		ZYNQ_I2C_CONTROL_HOLD);
 	/*
 	 * Temporarily disable restart (by clearing hold)
 	 * It doesn't seem to work.
 	 */
 	clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_HOLD);
 	writel(0xFF, &zynq_i2c->interrupt_status);
 	if (alen) {
 		clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_RW);
 		writel(dev, &zynq_i2c->address);
 		while (alen--)
 			writel(addr >> (8 * alen), &zynq_i2c->data);

 		/* Wait for the address to be sent */
 		if (!zynq_i2c_wait(zynq_i2c, ZYNQ_I2C_INTERRUPT_COMP)) {
 			/* Release the bus */
 			clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_HOLD);
 			return -ETIMEDOUT;
 		}
 		debug("Device acked address\n");
 	}

 	setbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_CLR_FIFO |
 		ZYNQ_I2C_CONTROL_RW);
 	/* Start reading data */
 	writel(dev, &zynq_i2c->address);
 	writel(length, &zynq_i2c->transfer_size);

 	/* Wait for data */
 	do {
 		status = zynq_i2c_wait(zynq_i2c, ZYNQ_I2C_INTERRUPT_COMP |
 			ZYNQ_I2C_INTERRUPT_DATA);
 		if (!status) {
 			/* Release the bus */
 			clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_HOLD);
 			return -ETIMEDOUT;
 		}
 		debug("Read %d bytes\n",
 		      length - readl(&zynq_i2c->transfer_size));
 		for (; i < length - readl(&zynq_i2c->transfer_size); i++)
 			*(cur_data++) = readl(&zynq_i2c->data);
 	} while (readl(&zynq_i2c->transfer_size) != 0);
 	/* All done... release the bus */
 	clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_HOLD);

 #ifdef DEBUG
 	zynq_i2c_debug_status(zynq_i2c);
 #endif
 	return 0;
 }

 /*
  * I2C write called by cmd_i2c when doing 'i2c write' and by cmd_eeprom.c
  * Begin write, send address byte(s), send data bytes, end.
  */
 static int zynq_i2c_write(struct i2c_adapter *adap, u8 dev, uint addr,
 			  int alen, u8 *data, int length)
 {
 	u8 *cur_data = data;
 	struct zynq_i2c_registers *zynq_i2c = i2c_select(adap);

 	/* Write the register address */
 	setbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_CLR_FIFO |
 		ZYNQ_I2C_CONTROL_HOLD);
 	clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_RW);
 	writel(0xFF, &zynq_i2c->interrupt_status);
 	writel(dev, &zynq_i2c->address);
 	if (alen) {
 		while (alen--)
 			writel(addr >> (8 * alen), &zynq_i2c->data);
 		/* Start the tranfer */
 		if (!zynq_i2c_wait(zynq_i2c, ZYNQ_I2C_INTERRUPT_COMP)) {
 			/* Release the bus */
 			clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_HOLD);
 			return -ETIMEDOUT;
 		}
 		debug("Device acked address\n");
 	}

 	while (length--) {
 		writel(*(cur_data++), &zynq_i2c->data);
 		if (readl(&zynq_i2c->transfer_size) == ZYNQ_I2C_FIFO_DEPTH) {
 			if (!zynq_i2c_wait(zynq_i2c, ZYNQ_I2C_INTERRUPT_COMP)) {
 				/* Release the bus */
 				clrbits_le32(&zynq_i2c->control,
 					     ZYNQ_I2C_CONTROL_HOLD);
 				return -ETIMEDOUT;
 			}
 		}
 	}

 	/* All done... release the bus */
 	clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_HOLD);
 	/* Wait for the address and data to be sent */
 	if (!zynq_i2c_wait(zynq_i2c, ZYNQ_I2C_INTERRUPT_COMP))
 		return -ETIMEDOUT;
 	return 0;
 }

 static unsigned int zynq_i2c_set_bus_speed(struct i2c_adapter *adap,
 			unsigned int speed)
 {
 	if (speed != 1000000)
 		return -EINVAL;

 	return 0;
 }

 U_BOOT_I2C_ADAP_COMPLETE(zynq_0, zynq_i2c_init, zynq_i2c_probe, zynq_i2c_read,
 			 zynq_i2c_write, zynq_i2c_set_bus_speed,
 			 CONFIG_SYS_I2C_ZYNQ_SPEED, CONFIG_SYS_I2C_ZYNQ_SLAVE,
 			 0)
 U_BOOT_I2C_ADAP_COMPLETE(zynq_1, zynq_i2c_init, zynq_i2c_probe, zynq_i2c_read,
 			 zynq_i2c_write, zynq_i2c_set_bus_speed,
 			 CONFIG_SYS_I2C_ZYNQ_SPEED, CONFIG_SYS_I2C_ZYNQ_SLAVE,
 			 1)
	/*
	* Driver for the Zynq-7000 PS I2C controller
	* IP from Cadence (ID T-CS-PE-0007-100, Version R1p10f2)
	*
	* Author: Joe Hershberger <joe.hershberger@ni.com>
	* Copyright (c) 2012 Joe Hershberger.
	*
	* Copyright (c) 2012-2013 Xilinx, Michal Simek
	*
	* SPDX-License-Identifier: GPL-2.0+
	*/

	#include <common.h>
	#include <asm/io.h>
	#include <i2c.h>
	#include <asm/errno.h>
	#include <asm/arch/hardware.h>

	/* i2c register set */
	struct zynq_i2c_registers {
	u32 control;
	u32 status;
	u32 address;
	u32 data;
	u32 interrupt_status;
	u32 transfer_size;
	u32 slave_mon_pause;
	u32 time_out;
	u32 interrupt_mask;
	u32 interrupt_enable;
	u32 interrupt_disable;
	};

	/* Control register fields */
	#define ZYNQ_I2C_CONTROL_RW 0x00000001
	#define ZYNQ_I2C_CONTROL_MS 0x00000002
	#define ZYNQ_I2C_CONTROL_NEA 0x00000004
	#define ZYNQ_I2C_CONTROL_ACKEN 0x00000008
	#define ZYNQ_I2C_CONTROL_HOLD 0x00000010
	#define ZYNQ_I2C_CONTROL_SLVMON 0x00000020
	#define ZYNQ_I2C_CONTROL_CLR_FIFO 0x00000040
	#define ZYNQ_I2C_CONTROL_DIV_B_SHIFT 8
	#define ZYNQ_I2C_CONTROL_DIV_B_MASK 0x00003F00
	#define ZYNQ_I2C_CONTROL_DIV_A_SHIFT 14
	#define ZYNQ_I2C_CONTROL_DIV_A_MASK 0x0000C000

	/* Status register values */
	#define ZYNQ_I2C_STATUS_RXDV 0x00000020
	#define ZYNQ_I2C_STATUS_TXDV 0x00000040
	#define ZYNQ_I2C_STATUS_RXOVF 0x00000080
	#define ZYNQ_I2C_STATUS_BA 0x00000100

	/* Interrupt register fields */
	#define ZYNQ_I2C_INTERRUPT_COMP 0x00000001
	#define ZYNQ_I2C_INTERRUPT_DATA 0x00000002
	#define ZYNQ_I2C_INTERRUPT_NACK 0x00000004
	#define ZYNQ_I2C_INTERRUPT_TO 0x00000008
	#define ZYNQ_I2C_INTERRUPT_SLVRDY 0x00000010
	#define ZYNQ_I2C_INTERRUPT_RXOVF 0x00000020
	#define ZYNQ_I2C_INTERRUPT_TXOVF 0x00000040
	#define ZYNQ_I2C_INTERRUPT_RXUNF 0x00000080
	#define ZYNQ_I2C_INTERRUPT_ARBLOST 0x00000200

	#define ZYNQ_I2C_FIFO_DEPTH 16
	#define ZYNQ_I2C_TRANSFERT_SIZE_MAX 255 /* Controller transfer limit */

	static struct zynq_i2c_registers i2c_select(struct i2c_adapter adap)
	{
	return adap->hwadapnr ?
	/* Zynq PS I2C1 */
	(struct zynq_i2c_registers *)ZYNQ_I2C_BASEADDR1 :
	/* Zynq PS I2C0 */
	(struct zynq_i2c_registers *)ZYNQ_I2C_BASEADDR0;
	}

	/* I2C init called by cmd_i2c when doing 'i2c reset'. */
	static void zynq_i2c_init(struct i2c_adapter *adap, int requested_speed,
	int slaveadd)
	{
	struct zynq_i2c_registers *zynq_i2c = i2c_select(adap);

	/* 111MHz / ( (3 * 17) * 22 ) = ~100KHz */
	writel((16 << ZYNQ_I2C_CONTROL_DIV_B_SHIFT) \|
	(2 << ZYNQ_I2C_CONTROL_DIV_A_SHIFT), &zynq_i2c->control);

	/* Enable master mode, ack, and 7-bit addressing */
	setbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_MS \|
	ZYNQ_I2C_CONTROL_ACKEN \| ZYNQ_I2C_CONTROL_NEA);
	}

	#ifdef DEBUG
	static void zynq_i2c_debug_status(struct zynq_i2c_registers *zynq_i2c)
	{
	int int_status;
	int status;
	int_status = readl(&zynq_i2c->interrupt_status);

	status = readl(&zynq_i2c->status);
	if (int_status \|\| status) {
	debug("Status: ");
	if (int_status & ZYNQ_I2C_INTERRUPT_COMP)
	debug("COMP ");
	if (int_status & ZYNQ_I2C_INTERRUPT_DATA)
	debug("DATA ");
	if (int_status & ZYNQ_I2C_INTERRUPT_NACK)
	debug("NACK ");
	if (int_status & ZYNQ_I2C_INTERRUPT_TO)
	debug("TO ");
	if (int_status & ZYNQ_I2C_INTERRUPT_SLVRDY)
	debug("SLVRDY ");
	if (int_status & ZYNQ_I2C_INTERRUPT_RXOVF)
	debug("RXOVF ");
	if (int_status & ZYNQ_I2C_INTERRUPT_TXOVF)
	debug("TXOVF ");
	if (int_status & ZYNQ_I2C_INTERRUPT_RXUNF)
	debug("RXUNF ");
	if (int_status & ZYNQ_I2C_INTERRUPT_ARBLOST)
	debug("ARBLOST ");
	if (status & ZYNQ_I2C_STATUS_RXDV)
	debug("RXDV ");
	if (status & ZYNQ_I2C_STATUS_TXDV)
	debug("TXDV ");
	if (status & ZYNQ_I2C_STATUS_RXOVF)
	debug("RXOVF ");
	if (status & ZYNQ_I2C_STATUS_BA)
	debug("BA ");
	debug("TS%d ", readl(&zynq_i2c->transfer_size));
	debug("\n");
	}
	}
	#endif

	/* Wait for an interrupt */
	static u32 zynq_i2c_wait(struct zynq_i2c_registers *zynq_i2c, u32 mask)
	{
	int timeout, int_status;

	for (timeout = 0; timeout < 100; timeout++) {
	udelay(100);
	int_status = readl(&zynq_i2c->interrupt_status);
	if (int_status & mask)
	break;
	}
	#ifdef DEBUG
	zynq_i2c_debug_status(zynq_i2c);
	#endif
	/* Clear interrupt status flags */
	writel(int_status & mask, &zynq_i2c->interrupt_status);

	return int_status & mask;
	}

	/*
	* I2C probe called by cmd_i2c when doing 'i2c probe'.
	* Begin read, nak data byte, end.
	*/
	static int zynq_i2c_probe(struct i2c_adapter *adap, u8 dev)
	{
	struct zynq_i2c_registers *zynq_i2c = i2c_select(adap);

	/* Attempt to read a byte */
	setbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_CLR_FIFO \|
	ZYNQ_I2C_CONTROL_RW);
	clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_HOLD);
	writel(0xFF, &zynq_i2c->interrupt_status);
	writel(dev, &zynq_i2c->address);
	writel(1, &zynq_i2c->transfer_size);

	return (zynq_i2c_wait(zynq_i2c, ZYNQ_I2C_INTERRUPT_COMP \|
	ZYNQ_I2C_INTERRUPT_NACK) &
	ZYNQ_I2C_INTERRUPT_COMP) ? 0 : -ETIMEDOUT;
	}

	/*
	* I2C read called by cmd_i2c when doing 'i2c read' and by cmd_eeprom.c
	* Begin write, send address byte(s), begin read, receive data bytes, end.
	*/
	static int zynq_i2c_read(struct i2c_adapter *adap, u8 dev, uint addr,
	int alen, u8 *data, int length)
	{
	u32 status;
	u32 i = 0;
	u8 *cur_data = data;
	struct zynq_i2c_registers *zynq_i2c = i2c_select(adap);

	/* Check the hardware can handle the requested bytes */
	if ((length < 0) \|\| (length > ZYNQ_I2C_TRANSFERT_SIZE_MAX))
	return -EINVAL;

	/* Write the register address */
	setbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_CLR_FIFO \|
	ZYNQ_I2C_CONTROL_HOLD);
	/*
	* Temporarily disable restart (by clearing hold)
	* It doesn't seem to work.
	*/
	clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_HOLD);
	writel(0xFF, &zynq_i2c->interrupt_status);
	if (alen) {
	clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_RW);
	writel(dev, &zynq_i2c->address);
	while (alen--)
	writel(addr >> (8 * alen), &zynq_i2c->data);

	/* Wait for the address to be sent */
	if (!zynq_i2c_wait(zynq_i2c, ZYNQ_I2C_INTERRUPT_COMP)) {
	/* Release the bus */
	clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_HOLD);
	return -ETIMEDOUT;
	}
	debug("Device acked address\n");
	}

	setbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_CLR_FIFO \|
	ZYNQ_I2C_CONTROL_RW);
	/* Start reading data */
	writel(dev, &zynq_i2c->address);
	writel(length, &zynq_i2c->transfer_size);

	/* Wait for data */
	do {
	status = zynq_i2c_wait(zynq_i2c, ZYNQ_I2C_INTERRUPT_COMP \|
	ZYNQ_I2C_INTERRUPT_DATA);
	if (!status) {
	/* Release the bus */
	clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_HOLD);
	return -ETIMEDOUT;
	}
	debug("Read %d bytes\n",
	length - readl(&zynq_i2c->transfer_size));
	for (; i < length - readl(&zynq_i2c->transfer_size); i++)
	*(cur_data++) = readl(&zynq_i2c->data);
	} while (readl(&zynq_i2c->transfer_size) != 0);
	/* All done... release the bus */
	clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_HOLD);

	#ifdef DEBUG
	zynq_i2c_debug_status(zynq_i2c);
	#endif
	return 0;
	}

	/*
	* I2C write called by cmd_i2c when doing 'i2c write' and by cmd_eeprom.c
	* Begin write, send address byte(s), send data bytes, end.
	*/
	static int zynq_i2c_write(struct i2c_adapter *adap, u8 dev, uint addr,
	int alen, u8 *data, int length)
	{
	u8 *cur_data = data;
	struct zynq_i2c_registers *zynq_i2c = i2c_select(adap);

	/* Write the register address */
	setbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_CLR_FIFO \|
	ZYNQ_I2C_CONTROL_HOLD);
	clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_RW);
	writel(0xFF, &zynq_i2c->interrupt_status);
	writel(dev, &zynq_i2c->address);
	if (alen) {
	while (alen--)
	writel(addr >> (8 * alen), &zynq_i2c->data);
	/* Start the tranfer */
	if (!zynq_i2c_wait(zynq_i2c, ZYNQ_I2C_INTERRUPT_COMP)) {
	/* Release the bus */
	clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_HOLD);
	return -ETIMEDOUT;
	}
	debug("Device acked address\n");
	}

	while (length--) {
	writel(*(cur_data++), &zynq_i2c->data);
	if (readl(&zynq_i2c->transfer_size) == ZYNQ_I2C_FIFO_DEPTH) {
	if (!zynq_i2c_wait(zynq_i2c, ZYNQ_I2C_INTERRUPT_COMP)) {
	/* Release the bus */
	clrbits_le32(&zynq_i2c->control,
	ZYNQ_I2C_CONTROL_HOLD);
	return -ETIMEDOUT;
	}
	}
	}

	/* All done... release the bus */
	clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_HOLD);
	/* Wait for the address and data to be sent */
	if (!zynq_i2c_wait(zynq_i2c, ZYNQ_I2C_INTERRUPT_COMP))
	return -ETIMEDOUT;
	return 0;
	}

	static unsigned int zynq_i2c_set_bus_speed(struct i2c_adapter *adap,
	unsigned int speed)
	{
	if (speed != 1000000)
	return -EINVAL;

	return 0;
	}

	U_BOOT_I2C_ADAP_COMPLETE(zynq_0, zynq_i2c_init, zynq_i2c_probe, zynq_i2c_read,
	zynq_i2c_write, zynq_i2c_set_bus_speed,
	CONFIG_SYS_I2C_ZYNQ_SPEED, CONFIG_SYS_I2C_ZYNQ_SLAVE,
	0)
	U_BOOT_I2C_ADAP_COMPLETE(zynq_1, zynq_i2c_init, zynq_i2c_probe, zynq_i2c_read,
	zynq_i2c_write, zynq_i2c_set_bus_speed,
	CONFIG_SYS_I2C_ZYNQ_SPEED, CONFIG_SYS_I2C_ZYNQ_SLAVE,
	1)