drivers/i2c/tegra_i2c.c - github/trini/u-boot - Gitiles

 /*
  * Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
  * Copyright (c) 2010-2011 NVIDIA Corporation
  *  NVIDIA Corporation <www.nvidia.com>
  *
  * SPDX-License-Identifier:	GPL-2.0+
  */

 #include <common.h>
 #include <dm.h>
 #include <errno.h>
 #include <fdtdec.h>
 #include <i2c.h>
 #include <asm/io.h>
 #include <asm/arch/clock.h>
 #include <asm/arch/funcmux.h>
 #include <asm/arch/gpio.h>
 #include <asm/arch/pinmux.h>
 #include <asm/arch-tegra/clk_rst.h>
 #include <asm/arch-tegra/tegra_i2c.h>

 DECLARE_GLOBAL_DATA_PTR;

 enum i2c_type {
 	TYPE_114,
 	TYPE_STD,
 	TYPE_DVC,
 };

 /* Information about i2c controller */
 struct i2c_bus {
 	int			id;
 	enum periph_id		periph_id;
 	int			speed;
 	int			pinmux_config;
 	struct i2c_control	*control;
 	struct i2c_ctlr		*regs;
 	enum i2c_type		type;
 	int			inited;	/* bus is inited */
 };

 static void set_packet_mode(struct i2c_bus *i2c_bus)
 {
 	u32 config;

 	config = I2C_CNFG_NEW_MASTER_FSM_MASK | I2C_CNFG_PACKET_MODE_MASK;

 	if (i2c_bus->type == TYPE_DVC) {
 		struct dvc_ctlr *dvc = (struct dvc_ctlr *)i2c_bus->regs;

 		writel(config, &dvc->cnfg);
 	} else {
 		writel(config, &i2c_bus->regs->cnfg);
 		/*
 		 * program I2C_SL_CNFG.NEWSL to ENABLE. This fixes probe
 		 * issues, i.e., some slaves may be wrongly detected.
 		 */
 		setbits_le32(&i2c_bus->regs->sl_cnfg, I2C_SL_CNFG_NEWSL_MASK);
 	}
 }

 static void i2c_reset_controller(struct i2c_bus *i2c_bus)
 {
 	/* Reset I2C controller. */
 	reset_periph(i2c_bus->periph_id, 1);

 	/* re-program config register to packet mode */
 	set_packet_mode(i2c_bus);
 }

 static void i2c_init_controller(struct i2c_bus *i2c_bus)
 {
 	if (!i2c_bus->speed)
 		return;
 	debug("%s: speed=%d\n", __func__, i2c_bus->speed);
 	/*
 	 * Use PLLP - DP-04508-001_v06 datasheet indicates a divisor of 8
 	 * here, in section 23.3.1, but in fact we seem to need a factor of
 	 * 16 to get the right frequency.
 	 */
 	clock_start_periph_pll(i2c_bus->periph_id, CLOCK_ID_PERIPH,
 		i2c_bus->speed * 2 * 8);

 	if (i2c_bus->type == TYPE_114) {
 		/*
 		 * T114 I2C went to a single clock source for standard/fast and
 		 * HS clock speeds. The new clock rate setting calculation is:
 		 *  SCL = CLK_SOURCE.I2C /
 		 *   (CLK_MULT_STD_FAST_MODE * (I2C_CLK_DIV_STD_FAST_MODE+1) *
 		 *   I2C FREQUENCY DIVISOR) as per the T114 TRM (sec 30.3.1).
 		 *
 		 * NOTE: We do this here, after the initial clock/pll start,
 		 * because if we read the clk_div reg before the controller
 		 * is running, we hang, and we need it for the new calc.
 		 */
 		int clk_div_stdfst_mode = readl(&i2c_bus->regs->clk_div) >> 16;
 		debug("%s: CLK_DIV_STD_FAST_MODE setting = %d\n", __func__,
 			clk_div_stdfst_mode);

 		clock_start_periph_pll(i2c_bus->periph_id, CLOCK_ID_PERIPH,
 			CLK_MULT_STD_FAST_MODE * (clk_div_stdfst_mode + 1) *
 			i2c_bus->speed * 2);
 	}

 	/* Reset I2C controller. */
 	i2c_reset_controller(i2c_bus);

 	/* Configure I2C controller. */
 	if (i2c_bus->type == TYPE_DVC) {	/* only for DVC I2C */
 		struct dvc_ctlr *dvc = (struct dvc_ctlr *)i2c_bus->regs;

 		setbits_le32(&dvc->ctrl3, DVC_CTRL_REG3_I2C_HW_SW_PROG_MASK);
 	}

 	funcmux_select(i2c_bus->periph_id, i2c_bus->pinmux_config);
 }

 static void send_packet_headers(
 	struct i2c_bus *i2c_bus,
 	struct i2c_trans_info *trans,
 	u32 packet_id,
 	bool end_with_repeated_start)
 {
 	u32 data;

 	/* prepare header1: Header size = 0 Protocol = I2C, pktType = 0 */
 	data = PROTOCOL_TYPE_I2C << PKT_HDR1_PROTOCOL_SHIFT;
 	data |= packet_id << PKT_HDR1_PKT_ID_SHIFT;
 	data |= i2c_bus->id << PKT_HDR1_CTLR_ID_SHIFT;
 	writel(data, &i2c_bus->control->tx_fifo);
 	debug("pkt header 1 sent (0x%x)\n", data);

 	/* prepare header2 */
 	data = (trans->num_bytes - 1) << PKT_HDR2_PAYLOAD_SIZE_SHIFT;
 	writel(data, &i2c_bus->control->tx_fifo);
 	debug("pkt header 2 sent (0x%x)\n", data);

 	/* prepare IO specific header: configure the slave address */
 	data = trans->address << PKT_HDR3_SLAVE_ADDR_SHIFT;

 	/* Enable Read if it is not a write transaction */
 	if (!(trans->flags & I2C_IS_WRITE))
 		data |= PKT_HDR3_READ_MODE_MASK;
 	if (end_with_repeated_start)
 		data |= PKT_HDR3_REPEAT_START_MASK;

 	/* Write I2C specific header */
 	writel(data, &i2c_bus->control->tx_fifo);
 	debug("pkt header 3 sent (0x%x)\n", data);
 }

 static int wait_for_tx_fifo_empty(struct i2c_control *control)
 {
 	u32 count;
 	int timeout_us = I2C_TIMEOUT_USEC;

 	while (timeout_us >= 0) {
 		count = (readl(&control->fifo_status) & TX_FIFO_EMPTY_CNT_MASK)
 				>> TX_FIFO_EMPTY_CNT_SHIFT;
 		if (count == I2C_FIFO_DEPTH)
 			return 1;
 		udelay(10);
 		timeout_us -= 10;
 	}

 	return 0;
 }

 static int wait_for_rx_fifo_notempty(struct i2c_control *control)
 {
 	u32 count;
 	int timeout_us = I2C_TIMEOUT_USEC;

 	while (timeout_us >= 0) {
 		count = (readl(&control->fifo_status) & TX_FIFO_FULL_CNT_MASK)
 				>> TX_FIFO_FULL_CNT_SHIFT;
 		if (count)
 			return 1;
 		udelay(10);
 		timeout_us -= 10;
 	}

 	return 0;
 }

 static int wait_for_transfer_complete(struct i2c_control *control)
 {
 	int int_status;
 	int timeout_us = I2C_TIMEOUT_USEC;

 	while (timeout_us >= 0) {
 		int_status = readl(&control->int_status);
 		if (int_status & I2C_INT_NO_ACK_MASK)
 			return -int_status;
 		if (int_status & I2C_INT_ARBITRATION_LOST_MASK)
 			return -int_status;
 		if (int_status & I2C_INT_XFER_COMPLETE_MASK)
 			return 0;

 		udelay(10);
 		timeout_us -= 10;
 	}

 	return -1;
 }

 static int send_recv_packets(struct i2c_bus *i2c_bus,
 			     struct i2c_trans_info *trans)
 {
 	struct i2c_control *control = i2c_bus->control;
 	u32 int_status;
 	u32 words;
 	u8 *dptr;
 	u32 local;
 	uchar last_bytes;
 	int error = 0;
 	int is_write = trans->flags & I2C_IS_WRITE;

 	/* clear status from previous transaction, XFER_COMPLETE, NOACK, etc. */
 	int_status = readl(&control->int_status);
 	writel(int_status, &control->int_status);

 	send_packet_headers(i2c_bus, trans, 1,
 			    trans->flags & I2C_USE_REPEATED_START);

 	words = DIV_ROUND_UP(trans->num_bytes, 4);
 	last_bytes = trans->num_bytes & 3;
 	dptr = trans->buf;

 	while (words) {
 		u32 *wptr = (u32 *)dptr;

 		if (is_write) {
 			/* deal with word alignment */
 			if ((words == 1) && last_bytes) {
 				local = 0;
 				memcpy(&local, dptr, last_bytes);
 			} else if ((unsigned)dptr & 3) {
 				memcpy(&local, dptr, sizeof(u32));
 			} else {
 				local = *wptr;
 			}
 			writel(local, &control->tx_fifo);
 			debug("pkt data sent (0x%x)\n", local);
 			if (!wait_for_tx_fifo_empty(control)) {
 				error = -1;
 				goto exit;
 			}
 		} else {
 			if (!wait_for_rx_fifo_notempty(control)) {
 				error = -1;
 				goto exit;
 			}
 			/*
 			 * for the last word, we read into our local buffer,
 			 * in case that caller did not provide enough buffer.
 			 */
 			local = readl(&control->rx_fifo);
 			if ((words == 1) && last_bytes)
 				memcpy(dptr, (char *)&local, last_bytes);
 			else if ((unsigned)dptr & 3)
 				memcpy(dptr, &local, sizeof(u32));
 			else
 				*wptr = local;
 			debug("pkt data received (0x%x)\n", local);
 		}
 		words--;
 		dptr += sizeof(u32);
 	}

 	if (wait_for_transfer_complete(control)) {
 		error = -1;
 		goto exit;
 	}
 	return 0;
 exit:
 	/* error, reset the controller. */
 	i2c_reset_controller(i2c_bus);

 	return error;
 }

 static int tegra_i2c_write_data(struct i2c_bus *i2c_bus, u32 addr, u8 *data,
 				u32 len, bool end_with_repeated_start)
 {
 	int error;
 	struct i2c_trans_info trans_info;

 	trans_info.address = addr;
 	trans_info.buf = data;
 	trans_info.flags = I2C_IS_WRITE;
 	if (end_with_repeated_start)
 		trans_info.flags |= I2C_USE_REPEATED_START;
 	trans_info.num_bytes = len;
 	trans_info.is_10bit_address = 0;

 	error = send_recv_packets(i2c_bus, &trans_info);
 	if (error)
 		debug("tegra_i2c_write_data: Error (%d) !!!\n", error);

 	return error;
 }

 static int tegra_i2c_read_data(struct i2c_bus *i2c_bus, u32 addr, u8 *data,
 			       u32 len)
 {
 	int error;
 	struct i2c_trans_info trans_info;

 	trans_info.address = addr | 1;
 	trans_info.buf = data;
 	trans_info.flags = 0;
 	trans_info.num_bytes = len;
 	trans_info.is_10bit_address = 0;

 	error = send_recv_packets(i2c_bus, &trans_info);
 	if (error)
 		debug("tegra_i2c_read_data: Error (%d) !!!\n", error);

 	return error;
 }

 static int tegra_i2c_set_bus_speed(struct udevice *dev, unsigned int speed)
 {
 	struct i2c_bus *i2c_bus = dev_get_priv(dev);

 	i2c_bus->speed = speed;
 	i2c_init_controller(i2c_bus);

 	return 0;
 }

 static int tegra_i2c_probe(struct udevice *dev)
 {
 	struct i2c_bus *i2c_bus = dev_get_priv(dev);
 	const void *blob = gd->fdt_blob;
 	int node = dev->of_offset;
 	bool is_dvc;

 	i2c_bus->id = dev->seq;
 	i2c_bus->type = dev_get_of_data(dev);
 	i2c_bus->regs = (struct i2c_ctlr *)fdtdec_get_addr(blob, node, "reg");

 	/*
 	 * We don't have a binding for pinmux yet. Leave it out for now. So
 	 * far no one needs anything other than the default.
 	 */
 	i2c_bus->pinmux_config = FUNCMUX_DEFAULT;
 	i2c_bus->periph_id = clock_decode_periph_id(blob, node);

 	/*
 	 * We can't specify the pinmux config in the fdt, so I2C2 will not
 	 * work on Seaboard. It normally has no devices on it anyway.
 	 * You could add in this little hack if you need to use it.
 	 * The correct solution is a pinmux binding in the fdt.
 	 *
 	 *	if (i2c_bus->periph_id == PERIPH_ID_I2C2)
 	 *		i2c_bus->pinmux_config = FUNCMUX_I2C2_PTA;
 	 */
 	if (i2c_bus->periph_id == -1)
 		return -EINVAL;

 	is_dvc = dev_get_of_data(dev) == TYPE_DVC;
 	if (is_dvc) {
 		i2c_bus->control =
 			&((struct dvc_ctlr *)i2c_bus->regs)->control;
 	} else {
 		i2c_bus->control = &i2c_bus->regs->control;
 	}
 	i2c_init_controller(i2c_bus);
 	debug("%s: controller bus %d at %p, periph_id %d, speed %d: ",
 	      is_dvc ? "dvc" : "i2c", dev->seq, i2c_bus->regs,
 	      i2c_bus->periph_id, i2c_bus->speed);

 	return 0;
 }

 /* i2c write version without the register address */
 static int i2c_write_data(struct i2c_bus *i2c_bus, uchar chip, uchar *buffer,
 			  int len, bool end_with_repeated_start)
 {
 	int rc;

 	debug("i2c_write_data: chip=0x%x, len=0x%x\n", chip, len);
 	debug("write_data: ");
 	/* use rc for counter */
 	for (rc = 0; rc < len; ++rc)
 		debug(" 0x%02x", buffer[rc]);
 	debug("\n");

 	/* Shift 7-bit address over for lower-level i2c functions */
 	rc = tegra_i2c_write_data(i2c_bus, chip << 1, buffer, len,
 				  end_with_repeated_start);
 	if (rc)
 		debug("i2c_write_data(): rc=%d\n", rc);

 	return rc;
 }

 /* i2c read version without the register address */
 static int i2c_read_data(struct i2c_bus *i2c_bus, uchar chip, uchar *buffer,
 			 int len)
 {
 	int rc;

 	debug("inside i2c_read_data():\n");
 	/* Shift 7-bit address over for lower-level i2c functions */
 	rc = tegra_i2c_read_data(i2c_bus, chip << 1, buffer, len);
 	if (rc) {
 		debug("i2c_read_data(): rc=%d\n", rc);
 		return rc;
 	}

 	debug("i2c_read_data: ");
 	/* reuse rc for counter*/
 	for (rc = 0; rc < len; ++rc)
 		debug(" 0x%02x", buffer[rc]);
 	debug("\n");

 	return 0;
 }

 /* Probe to see if a chip is present. */
 static int tegra_i2c_probe_chip(struct udevice *bus, uint chip_addr,
 				uint chip_flags)
 {
 	struct i2c_bus *i2c_bus = dev_get_priv(bus);
 	int rc;
 	u8 reg;

 	/* Shift 7-bit address over for lower-level i2c functions */
 	rc = tegra_i2c_write_data(i2c_bus, chip_addr << 1, &reg, sizeof(reg),
 				  false);

 	return rc;
 }

 static int tegra_i2c_xfer(struct udevice *bus, struct i2c_msg *msg,
 			  int nmsgs)
 {
 	struct i2c_bus *i2c_bus = dev_get_priv(bus);
 	int ret;

 	debug("i2c_xfer: %d messages\n", nmsgs);
 	for (; nmsgs > 0; nmsgs--, msg++) {
 		bool next_is_read = nmsgs > 1 && (msg[1].flags & I2C_M_RD);

 		debug("i2c_xfer: chip=0x%x, len=0x%x\n", msg->addr, msg->len);
 		if (msg->flags & I2C_M_RD) {
 			ret = i2c_read_data(i2c_bus, msg->addr, msg->buf,
 					    msg->len);
 		} else {
 			ret = i2c_write_data(i2c_bus, msg->addr, msg->buf,
 					     msg->len, next_is_read);
 		}
 		if (ret) {
 			debug("i2c_write: error sending\n");
 			return -EREMOTEIO;
 		}
 	}

 	return 0;
 }

 int tegra_i2c_get_dvc_bus(struct udevice **busp)
 {
 	struct udevice *bus;

 	for (uclass_first_device(UCLASS_I2C, &bus);
 	     bus;
 	     uclass_next_device(&bus)) {
 		if (dev_get_of_data(bus) == TYPE_DVC) {
 			*busp = bus;
 			return 0;
 		}
 	}

 	return -ENODEV;
 }

 static const struct dm_i2c_ops tegra_i2c_ops = {
 	.xfer		= tegra_i2c_xfer,
 	.probe_chip	= tegra_i2c_probe_chip,
 	.set_bus_speed	= tegra_i2c_set_bus_speed,
 };

 static int tegra_i2c_child_pre_probe(struct udevice *dev)
 {
 	struct dm_i2c_chip *i2c_chip = dev_get_parentdata(dev);

 	if (dev->of_offset == -1)
 		return 0;
 	return i2c_chip_ofdata_to_platdata(gd->fdt_blob, dev->of_offset,
 					   i2c_chip);
 }

 static int tegra_i2c_ofdata_to_platdata(struct udevice *dev)
 {
 	return 0;
 }

 static const struct udevice_id tegra_i2c_ids[] = {
 	{ .compatible = "nvidia,tegra114-i2c", .data = TYPE_114 },
 	{ .compatible = "nvidia,tegra20-i2c", .data = TYPE_STD },
 	{ .compatible = "nvidia,tegra20-i2c-dvc", .data = TYPE_DVC },
 	{ }
 };

 U_BOOT_DRIVER(i2c_tegra) = {
 	.name	= "i2c_tegra",
 	.id	= UCLASS_I2C,
 	.of_match = tegra_i2c_ids,
 	.ofdata_to_platdata = tegra_i2c_ofdata_to_platdata,
 	.probe	= tegra_i2c_probe,
 	.per_child_auto_alloc_size = sizeof(struct dm_i2c_chip),
 	.child_pre_probe = tegra_i2c_child_pre_probe,
 	.priv_auto_alloc_size = sizeof(struct i2c_bus),
 	.ops	= &tegra_i2c_ops,
 };
	/*
	* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
	* Copyright (c) 2010-2011 NVIDIA Corporation
	* NVIDIA Corporation <www.nvidia.com>
	*
	* SPDX-License-Identifier: GPL-2.0+
	*/

	#include <common.h>
	#include <dm.h>
	#include <errno.h>
	#include <fdtdec.h>
	#include <i2c.h>
	#include <asm/io.h>
	#include <asm/arch/clock.h>
	#include <asm/arch/funcmux.h>
	#include <asm/arch/gpio.h>
	#include <asm/arch/pinmux.h>
	#include <asm/arch-tegra/clk_rst.h>
	#include <asm/arch-tegra/tegra_i2c.h>

	DECLARE_GLOBAL_DATA_PTR;

	enum i2c_type {
	TYPE_114,
	TYPE_STD,
	TYPE_DVC,
	};

	/* Information about i2c controller */
	struct i2c_bus {
	int id;
	enum periph_id periph_id;
	int speed;
	int pinmux_config;
	struct i2c_control *control;
	struct i2c_ctlr *regs;
	enum i2c_type type;
	int inited; /* bus is inited */
	};

	static void set_packet_mode(struct i2c_bus *i2c_bus)
	{
	u32 config;

	config = I2C_CNFG_NEW_MASTER_FSM_MASK \| I2C_CNFG_PACKET_MODE_MASK;

	if (i2c_bus->type == TYPE_DVC) {
	struct dvc_ctlr dvc = (struct dvc_ctlr )i2c_bus->regs;

	writel(config, &dvc->cnfg);
	} else {
	writel(config, &i2c_bus->regs->cnfg);
	/*
	* program I2C_SL_CNFG.NEWSL to ENABLE. This fixes probe
	* issues, i.e., some slaves may be wrongly detected.
	*/
	setbits_le32(&i2c_bus->regs->sl_cnfg, I2C_SL_CNFG_NEWSL_MASK);
	}
	}

	static void i2c_reset_controller(struct i2c_bus *i2c_bus)
	{
	/* Reset I2C controller. */
	reset_periph(i2c_bus->periph_id, 1);

	/* re-program config register to packet mode */
	set_packet_mode(i2c_bus);
	}

	static void i2c_init_controller(struct i2c_bus *i2c_bus)
	{
	if (!i2c_bus->speed)
	return;
	debug("%s: speed=%d\n", __func__, i2c_bus->speed);
	/*
	* Use PLLP - DP-04508-001_v06 datasheet indicates a divisor of 8
	* here, in section 23.3.1, but in fact we seem to need a factor of
	* 16 to get the right frequency.
	*/
	clock_start_periph_pll(i2c_bus->periph_id, CLOCK_ID_PERIPH,
	i2c_bus->speed * 2 * 8);

	if (i2c_bus->type == TYPE_114) {
	/*
	* T114 I2C went to a single clock source for standard/fast and
	* HS clock speeds. The new clock rate setting calculation is:
	* SCL = CLK_SOURCE.I2C /
	* (CLK_MULT_STD_FAST_MODE * (I2C_CLK_DIV_STD_FAST_MODE+1) *
	* I2C FREQUENCY DIVISOR) as per the T114 TRM (sec 30.3.1).
	*
	* NOTE: We do this here, after the initial clock/pll start,
	* because if we read the clk_div reg before the controller
	* is running, we hang, and we need it for the new calc.
	*/
	int clk_div_stdfst_mode = readl(&i2c_bus->regs->clk_div) >> 16;
	debug("%s: CLK_DIV_STD_FAST_MODE setting = %d\n", __func__,
	clk_div_stdfst_mode);

	clock_start_periph_pll(i2c_bus->periph_id, CLOCK_ID_PERIPH,
	CLK_MULT_STD_FAST_MODE * (clk_div_stdfst_mode + 1) *
	i2c_bus->speed * 2);
	}

	/* Reset I2C controller. */
	i2c_reset_controller(i2c_bus);

	/* Configure I2C controller. */
	if (i2c_bus->type == TYPE_DVC) { /* only for DVC I2C */
	struct dvc_ctlr dvc = (struct dvc_ctlr )i2c_bus->regs;

	setbits_le32(&dvc->ctrl3, DVC_CTRL_REG3_I2C_HW_SW_PROG_MASK);
	}

	funcmux_select(i2c_bus->periph_id, i2c_bus->pinmux_config);
	}

	static void send_packet_headers(
	struct i2c_bus *i2c_bus,
	struct i2c_trans_info *trans,
	u32 packet_id,
	bool end_with_repeated_start)
	{
	u32 data;

	/* prepare header1: Header size = 0 Protocol = I2C, pktType = 0 */
	data = PROTOCOL_TYPE_I2C << PKT_HDR1_PROTOCOL_SHIFT;
	data \|= packet_id << PKT_HDR1_PKT_ID_SHIFT;
	data \|= i2c_bus->id << PKT_HDR1_CTLR_ID_SHIFT;
	writel(data, &i2c_bus->control->tx_fifo);
	debug("pkt header 1 sent (0x%x)\n", data);

	/* prepare header2 */
	data = (trans->num_bytes - 1) << PKT_HDR2_PAYLOAD_SIZE_SHIFT;
	writel(data, &i2c_bus->control->tx_fifo);
	debug("pkt header 2 sent (0x%x)\n", data);

	/* prepare IO specific header: configure the slave address */
	data = trans->address << PKT_HDR3_SLAVE_ADDR_SHIFT;

	/* Enable Read if it is not a write transaction */
	if (!(trans->flags & I2C_IS_WRITE))
	data \|= PKT_HDR3_READ_MODE_MASK;
	if (end_with_repeated_start)
	data \|= PKT_HDR3_REPEAT_START_MASK;

	/* Write I2C specific header */
	writel(data, &i2c_bus->control->tx_fifo);
	debug("pkt header 3 sent (0x%x)\n", data);
	}

	static int wait_for_tx_fifo_empty(struct i2c_control *control)
	{
	u32 count;
	int timeout_us = I2C_TIMEOUT_USEC;

	while (timeout_us >= 0) {
	count = (readl(&control->fifo_status) & TX_FIFO_EMPTY_CNT_MASK)
	>> TX_FIFO_EMPTY_CNT_SHIFT;
	if (count == I2C_FIFO_DEPTH)
	return 1;
	udelay(10);
	timeout_us -= 10;
	}

	return 0;
	}

	static int wait_for_rx_fifo_notempty(struct i2c_control *control)
	{
	u32 count;
	int timeout_us = I2C_TIMEOUT_USEC;

	while (timeout_us >= 0) {
	count = (readl(&control->fifo_status) & TX_FIFO_FULL_CNT_MASK)
	>> TX_FIFO_FULL_CNT_SHIFT;
	if (count)
	return 1;
	udelay(10);
	timeout_us -= 10;
	}

	return 0;
	}

	static int wait_for_transfer_complete(struct i2c_control *control)
	{
	int int_status;
	int timeout_us = I2C_TIMEOUT_USEC;

	while (timeout_us >= 0) {
	int_status = readl(&control->int_status);
	if (int_status & I2C_INT_NO_ACK_MASK)
	return -int_status;
	if (int_status & I2C_INT_ARBITRATION_LOST_MASK)
	return -int_status;
	if (int_status & I2C_INT_XFER_COMPLETE_MASK)
	return 0;

	udelay(10);
	timeout_us -= 10;
	}

	return -1;
	}

	static int send_recv_packets(struct i2c_bus *i2c_bus,
	struct i2c_trans_info *trans)
	{
	struct i2c_control *control = i2c_bus->control;
	u32 int_status;
	u32 words;
	u8 *dptr;
	u32 local;
	uchar last_bytes;
	int error = 0;
	int is_write = trans->flags & I2C_IS_WRITE;

	/* clear status from previous transaction, XFER_COMPLETE, NOACK, etc. */
	int_status = readl(&control->int_status);
	writel(int_status, &control->int_status);

	send_packet_headers(i2c_bus, trans, 1,
	trans->flags & I2C_USE_REPEATED_START);

	words = DIV_ROUND_UP(trans->num_bytes, 4);
	last_bytes = trans->num_bytes & 3;
	dptr = trans->buf;

	while (words) {
	u32 wptr = (u32 )dptr;

	if (is_write) {
	/* deal with word alignment */
	if ((words == 1) && last_bytes) {
	local = 0;
	memcpy(&local, dptr, last_bytes);
	} else if ((unsigned)dptr & 3) {
	memcpy(&local, dptr, sizeof(u32));
	} else {
	local = *wptr;
	}
	writel(local, &control->tx_fifo);
	debug("pkt data sent (0x%x)\n", local);
	if (!wait_for_tx_fifo_empty(control)) {
	error = -1;
	goto exit;
	}
	} else {
	if (!wait_for_rx_fifo_notempty(control)) {
	error = -1;
	goto exit;
	}
	/*
	* for the last word, we read into our local buffer,
	* in case that caller did not provide enough buffer.
	*/
	local = readl(&control->rx_fifo);
	if ((words == 1) && last_bytes)
	memcpy(dptr, (char *)&local, last_bytes);
	else if ((unsigned)dptr & 3)
	memcpy(dptr, &local, sizeof(u32));
	else
	*wptr = local;
	debug("pkt data received (0x%x)\n", local);
	}
	words--;
	dptr += sizeof(u32);
	}

	if (wait_for_transfer_complete(control)) {
	error = -1;
	goto exit;
	}
	return 0;
	exit:
	/* error, reset the controller. */
	i2c_reset_controller(i2c_bus);

	return error;
	}

	static int tegra_i2c_write_data(struct i2c_bus i2c_bus, u32 addr, u8 data,
	u32 len, bool end_with_repeated_start)
	{
	int error;
	struct i2c_trans_info trans_info;

	trans_info.address = addr;
	trans_info.buf = data;
	trans_info.flags = I2C_IS_WRITE;
	if (end_with_repeated_start)
	trans_info.flags \|= I2C_USE_REPEATED_START;
	trans_info.num_bytes = len;
	trans_info.is_10bit_address = 0;

	error = send_recv_packets(i2c_bus, &trans_info);
	if (error)
	debug("tegra_i2c_write_data: Error (%d) !!!\n", error);

	return error;
	}

	static int tegra_i2c_read_data(struct i2c_bus i2c_bus, u32 addr, u8 data,
	u32 len)
	{
	int error;
	struct i2c_trans_info trans_info;

	trans_info.address = addr \| 1;
	trans_info.buf = data;
	trans_info.flags = 0;
	trans_info.num_bytes = len;
	trans_info.is_10bit_address = 0;

	error = send_recv_packets(i2c_bus, &trans_info);
	if (error)
	debug("tegra_i2c_read_data: Error (%d) !!!\n", error);

	return error;
	}

	static int tegra_i2c_set_bus_speed(struct udevice *dev, unsigned int speed)
	{
	struct i2c_bus *i2c_bus = dev_get_priv(dev);

	i2c_bus->speed = speed;
	i2c_init_controller(i2c_bus);

	return 0;
	}

	static int tegra_i2c_probe(struct udevice *dev)
	{
	struct i2c_bus *i2c_bus = dev_get_priv(dev);
	const void *blob = gd->fdt_blob;
	int node = dev->of_offset;
	bool is_dvc;

	i2c_bus->id = dev->seq;
	i2c_bus->type = dev_get_of_data(dev);
	i2c_bus->regs = (struct i2c_ctlr *)fdtdec_get_addr(blob, node, "reg");

	/*
	* We don't have a binding for pinmux yet. Leave it out for now. So
	* far no one needs anything other than the default.
	*/
	i2c_bus->pinmux_config = FUNCMUX_DEFAULT;
	i2c_bus->periph_id = clock_decode_periph_id(blob, node);

	/*
	* We can't specify the pinmux config in the fdt, so I2C2 will not
	* work on Seaboard. It normally has no devices on it anyway.
	* You could add in this little hack if you need to use it.
	* The correct solution is a pinmux binding in the fdt.
	*
	* if (i2c_bus->periph_id == PERIPH_ID_I2C2)
	* i2c_bus->pinmux_config = FUNCMUX_I2C2_PTA;
	*/
	if (i2c_bus->periph_id == -1)
	return -EINVAL;

	is_dvc = dev_get_of_data(dev) == TYPE_DVC;
	if (is_dvc) {
	i2c_bus->control =
	&((struct dvc_ctlr *)i2c_bus->regs)->control;
	} else {
	i2c_bus->control = &i2c_bus->regs->control;
	}
	i2c_init_controller(i2c_bus);
	debug("%s: controller bus %d at %p, periph_id %d, speed %d: ",
	is_dvc ? "dvc" : "i2c", dev->seq, i2c_bus->regs,
	i2c_bus->periph_id, i2c_bus->speed);

	return 0;
	}

	/* i2c write version without the register address */
	static int i2c_write_data(struct i2c_bus i2c_bus, uchar chip, uchar buffer,
	int len, bool end_with_repeated_start)
	{
	int rc;

	debug("i2c_write_data: chip=0x%x, len=0x%x\n", chip, len);
	debug("write_data: ");
	/* use rc for counter */
	for (rc = 0; rc < len; ++rc)
	debug(" 0x%02x", buffer[rc]);
	debug("\n");

	/* Shift 7-bit address over for lower-level i2c functions */
	rc = tegra_i2c_write_data(i2c_bus, chip << 1, buffer, len,
	end_with_repeated_start);
	if (rc)
	debug("i2c_write_data(): rc=%d\n", rc);

	return rc;
	}

	/* i2c read version without the register address */
	static int i2c_read_data(struct i2c_bus i2c_bus, uchar chip, uchar buffer,
	int len)
	{
	int rc;

	debug("inside i2c_read_data():\n");
	/* Shift 7-bit address over for lower-level i2c functions */
	rc = tegra_i2c_read_data(i2c_bus, chip << 1, buffer, len);
	if (rc) {
	debug("i2c_read_data(): rc=%d\n", rc);
	return rc;
	}

	debug("i2c_read_data: ");
	/* reuse rc for counter*/
	for (rc = 0; rc < len; ++rc)
	debug(" 0x%02x", buffer[rc]);
	debug("\n");

	return 0;
	}

	/* Probe to see if a chip is present. */
	static int tegra_i2c_probe_chip(struct udevice *bus, uint chip_addr,
	uint chip_flags)
	{
	struct i2c_bus *i2c_bus = dev_get_priv(bus);
	int rc;
	u8 reg;

	/* Shift 7-bit address over for lower-level i2c functions */
	rc = tegra_i2c_write_data(i2c_bus, chip_addr << 1, &reg, sizeof(reg),
	false);

	return rc;
	}

	static int tegra_i2c_xfer(struct udevice bus, struct i2c_msg msg,
	int nmsgs)
	{
	struct i2c_bus *i2c_bus = dev_get_priv(bus);
	int ret;

	debug("i2c_xfer: %d messages\n", nmsgs);
	for (; nmsgs > 0; nmsgs--, msg++) {
	bool next_is_read = nmsgs > 1 && (msg[1].flags & I2C_M_RD);

	debug("i2c_xfer: chip=0x%x, len=0x%x\n", msg->addr, msg->len);
	if (msg->flags & I2C_M_RD) {
	ret = i2c_read_data(i2c_bus, msg->addr, msg->buf,
	msg->len);
	} else {
	ret = i2c_write_data(i2c_bus, msg->addr, msg->buf,
	msg->len, next_is_read);
	}
	if (ret) {
	debug("i2c_write: error sending\n");
	return -EREMOTEIO;
	}
	}

	return 0;
	}

	int tegra_i2c_get_dvc_bus(struct udevice **busp)
	{
	struct udevice *bus;

	for (uclass_first_device(UCLASS_I2C, &bus);
	bus;
	uclass_next_device(&bus)) {
	if (dev_get_of_data(bus) == TYPE_DVC) {
	*busp = bus;
	return 0;
	}
	}

	return -ENODEV;
	}

	static const struct dm_i2c_ops tegra_i2c_ops = {
	.xfer = tegra_i2c_xfer,
	.probe_chip = tegra_i2c_probe_chip,
	.set_bus_speed = tegra_i2c_set_bus_speed,
	};

	static int tegra_i2c_child_pre_probe(struct udevice *dev)
	{
	struct dm_i2c_chip *i2c_chip = dev_get_parentdata(dev);

	if (dev->of_offset == -1)
	return 0;
	return i2c_chip_ofdata_to_platdata(gd->fdt_blob, dev->of_offset,
	i2c_chip);
	}

	static int tegra_i2c_ofdata_to_platdata(struct udevice *dev)
	{
	return 0;
	}

	static const struct udevice_id tegra_i2c_ids[] = {
	{ .compatible = "nvidia,tegra114-i2c", .data = TYPE_114 },
	{ .compatible = "nvidia,tegra20-i2c", .data = TYPE_STD },
	{ .compatible = "nvidia,tegra20-i2c-dvc", .data = TYPE_DVC },
	{ }
	};

	U_BOOT_DRIVER(i2c_tegra) = {
	.name = "i2c_tegra",
	.id = UCLASS_I2C,
	.of_match = tegra_i2c_ids,
	.ofdata_to_platdata = tegra_i2c_ofdata_to_platdata,
	.probe = tegra_i2c_probe,
	.per_child_auto_alloc_size = sizeof(struct dm_i2c_chip),
	.child_pre_probe = tegra_i2c_child_pre_probe,
	.priv_auto_alloc_size = sizeof(struct i2c_bus),
	.ops = &tegra_i2c_ops,
	};