drivers/i2c/i2c-uclass.c - platform/external/u-boot - Gitiles

 /*
  * Copyright (c) 2014 Google, Inc
  *
  * SPDX-License-Identifier:	GPL-2.0+
  */

 #include <common.h>
 #include <dm.h>
 #include <errno.h>
 #include <fdtdec.h>
 #include <i2c.h>
 #include <malloc.h>
 #include <dm/device-internal.h>
 #include <dm/lists.h>

 DECLARE_GLOBAL_DATA_PTR;

 #define I2C_MAX_OFFSET_LEN	4

 /* Useful debugging function */
 void i2c_dump_msgs(struct i2c_msg *msg, int nmsgs)
 {
 	int i;

 	for (i = 0; i < nmsgs; i++) {
 		struct i2c_msg *m = &msg[i];

 		printf("   %s %x len=%x", m->flags & I2C_M_RD ? "R" : "W",
 		       msg->addr, msg->len);
 		if (!(m->flags & I2C_M_RD))
 			printf(": %x", m->buf[0]);
 		printf("\n");
 	}
 }

 /**
  * i2c_setup_offset() - Set up a new message with a chip offset
  *
  * @chip:	Chip to use
  * @offset:	Byte offset within chip
  * @offset_buf:	Place to put byte offset
  * @msg:	Message buffer
  * @return 0 if OK, -EADDRNOTAVAIL if the offset length is 0. In that case the
  * message is still set up but will not contain an offset.
  */
 static int i2c_setup_offset(struct dm_i2c_chip *chip, uint offset,
 			    uint8_t offset_buf[], struct i2c_msg *msg)
 {
 	int offset_len;

 	msg->addr = chip->chip_addr;
 	msg->flags = chip->flags & DM_I2C_CHIP_10BIT ? I2C_M_TEN : 0;
 	msg->len = chip->offset_len;
 	msg->buf = offset_buf;
 	if (!chip->offset_len)
 		return -EADDRNOTAVAIL;
 	assert(chip->offset_len <= I2C_MAX_OFFSET_LEN);
 	offset_len = chip->offset_len;
 	while (offset_len--)
 		*offset_buf++ = offset >> (8 * offset_len);

 	return 0;
 }

 static int i2c_read_bytewise(struct udevice *dev, uint offset,
 			     uint8_t *buffer, int len)
 {
 	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
 	struct udevice *bus = dev_get_parent(dev);
 	struct dm_i2c_ops *ops = i2c_get_ops(bus);
 	struct i2c_msg msg[2], *ptr;
 	uint8_t offset_buf[I2C_MAX_OFFSET_LEN];
 	int ret;
 	int i;

 	for (i = 0; i < len; i++) {
 		if (i2c_setup_offset(chip, offset + i, offset_buf, msg))
 			return -EINVAL;
 		ptr = msg + 1;
 		ptr->addr = chip->chip_addr;
 		ptr->flags = msg->flags | I2C_M_RD;
 		ptr->len = 1;
 		ptr->buf = &buffer[i];
 		ptr++;

 		ret = ops->xfer(bus, msg, ptr - msg);
 		if (ret)
 			return ret;
 	}

 	return 0;
 }

 static int i2c_write_bytewise(struct udevice *dev, uint offset,
 			     const uint8_t *buffer, int len)
 {
 	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
 	struct udevice *bus = dev_get_parent(dev);
 	struct dm_i2c_ops *ops = i2c_get_ops(bus);
 	struct i2c_msg msg[1];
 	uint8_t buf[I2C_MAX_OFFSET_LEN + 1];
 	int ret;
 	int i;

 	for (i = 0; i < len; i++) {
 		if (i2c_setup_offset(chip, offset + i, buf, msg))
 			return -EINVAL;
 		buf[msg->len++] = buffer[i];

 		ret = ops->xfer(bus, msg, 1);
 		if (ret)
 			return ret;
 	}

 	return 0;
 }

 int dm_i2c_read(struct udevice *dev, uint offset, uint8_t *buffer, int len)
 {
 	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
 	struct udevice *bus = dev_get_parent(dev);
 	struct dm_i2c_ops *ops = i2c_get_ops(bus);
 	struct i2c_msg msg[2], *ptr;
 	uint8_t offset_buf[I2C_MAX_OFFSET_LEN];
 	int msg_count;

 	if (!ops->xfer)
 		return -ENOSYS;
 	if (chip->flags & DM_I2C_CHIP_RD_ADDRESS)
 		return i2c_read_bytewise(dev, offset, buffer, len);
 	ptr = msg;
 	if (!i2c_setup_offset(chip, offset, offset_buf, ptr))
 		ptr++;

 	if (len) {
 		ptr->addr = chip->chip_addr;
 		ptr->flags = chip->flags & DM_I2C_CHIP_10BIT ? I2C_M_TEN : 0;
 		ptr->flags |= I2C_M_RD;
 		ptr->len = len;
 		ptr->buf = buffer;
 		ptr++;
 	}
 	msg_count = ptr - msg;

 	return ops->xfer(bus, msg, msg_count);
 }

 int dm_i2c_write(struct udevice *dev, uint offset, const uint8_t *buffer,
 		 int len)
 {
 	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
 	struct udevice *bus = dev_get_parent(dev);
 	struct dm_i2c_ops *ops = i2c_get_ops(bus);
 	struct i2c_msg msg[1];

 	if (!ops->xfer)
 		return -ENOSYS;

 	if (chip->flags & DM_I2C_CHIP_WR_ADDRESS)
 		return i2c_write_bytewise(dev, offset, buffer, len);
 	/*
 	 * The simple approach would be to send two messages here: one to
 	 * set the offset and one to write the bytes. However some drivers
 	 * will not be expecting this, and some chips won't like how the
 	 * driver presents this on the I2C bus.
 	 *
 	 * The API does not support separate offset and data. We could extend
 	 * it with a flag indicating that there is data in the next message
 	 * that needs to be processed in the same transaction. We could
 	 * instead add an additional buffer to each message. For now, handle
 	 * this in the uclass since it isn't clear what the impact on drivers
 	 * would be with this extra complication. Unfortunately this means
 	 * copying the message.
 	 *
 	 * Use the stack for small messages, malloc() for larger ones. We
 	 * need to allow space for the offset (up to 4 bytes) and the message
 	 * itself.
 	 */
 	if (len < 64) {
 		uint8_t buf[I2C_MAX_OFFSET_LEN + len];

 		i2c_setup_offset(chip, offset, buf, msg);
 		msg->len += len;
 		memcpy(buf + chip->offset_len, buffer, len);

 		return ops->xfer(bus, msg, 1);
 	} else {
 		uint8_t *buf;
 		int ret;

 		buf = malloc(I2C_MAX_OFFSET_LEN + len);
 		if (!buf)
 			return -ENOMEM;
 		i2c_setup_offset(chip, offset, buf, msg);
 		msg->len += len;
 		memcpy(buf + chip->offset_len, buffer, len);

 		ret = ops->xfer(bus, msg, 1);
 		free(buf);
 		return ret;
 	}
 }

 int dm_i2c_xfer(struct udevice *dev, struct i2c_msg *msg, int nmsgs)
 {
 	struct udevice *bus = dev_get_parent(dev);
 	struct dm_i2c_ops *ops = i2c_get_ops(bus);

 	if (!ops->xfer)
 		return -ENOSYS;

 	return ops->xfer(bus, msg, nmsgs);
 }

 int dm_i2c_reg_read(struct udevice *dev, uint offset)
 {
 	uint8_t val;
 	int ret;

 	ret = dm_i2c_read(dev, offset, &val, 1);
 	if (ret < 0)
 		return ret;

 	return val;
 }

 int dm_i2c_reg_write(struct udevice *dev, uint offset, uint value)
 {
 	uint8_t val = value;

 	return dm_i2c_write(dev, offset, &val, 1);
 }

 /**
  * i2c_probe_chip() - probe for a chip on a bus
  *
  * @bus:	Bus to probe
  * @chip_addr:	Chip address to probe
  * @flags:	Flags for the chip
  * @return 0 if found, -ENOSYS if the driver is invalid, -EREMOTEIO if the chip
  * does not respond to probe
  */
 static int i2c_probe_chip(struct udevice *bus, uint chip_addr,
 			  enum dm_i2c_chip_flags chip_flags)
 {
 	struct dm_i2c_ops *ops = i2c_get_ops(bus);
 	struct i2c_msg msg[1];
 	int ret;

 	if (ops->probe_chip) {
 		ret = ops->probe_chip(bus, chip_addr, chip_flags);
 		if (!ret || ret != -ENOSYS)
 			return ret;
 	}

 	if (!ops->xfer)
 		return -ENOSYS;

 	/* Probe with a zero-length message */
 	msg->addr = chip_addr;
 	msg->flags = chip_flags & DM_I2C_CHIP_10BIT ? I2C_M_TEN : 0;
 	msg->len = 0;
 	msg->buf = NULL;

 	return ops->xfer(bus, msg, 1);
 }

 static int i2c_bind_driver(struct udevice *bus, uint chip_addr, uint offset_len,
 			   struct udevice **devp)
 {
 	struct dm_i2c_chip *chip;
 	char name[30], *str;
 	struct udevice *dev;
 	int ret;

 	snprintf(name, sizeof(name), "generic_%x", chip_addr);
 	str = strdup(name);
 	if (!str)
 		return -ENOMEM;
 	ret = device_bind_driver(bus, "i2c_generic_chip_drv", str, &dev);
 	debug("%s:  device_bind_driver: ret=%d\n", __func__, ret);
 	if (ret)
 		goto err_bind;

 	/* Tell the device what we know about it */
 	chip = dev_get_parent_platdata(dev);
 	chip->chip_addr = chip_addr;
 	chip->offset_len = offset_len;
 	ret = device_probe(dev);
 	debug("%s:  device_probe: ret=%d\n", __func__, ret);
 	if (ret)
 		goto err_probe;

 	*devp = dev;
 	return 0;

 err_probe:
 	/*
 	 * If the device failed to probe, unbind it. There is nothing there
 	 * on the bus so we don't want to leave it lying around
 	 */
 	device_unbind(dev);
 err_bind:
 	free(str);
 	return ret;
 }

 int i2c_get_chip(struct udevice *bus, uint chip_addr, uint offset_len,
 		 struct udevice **devp)
 {
 	struct udevice *dev;

 	debug("%s: Searching bus '%s' for address %02x: ", __func__,
 	      bus->name, chip_addr);
 	for (device_find_first_child(bus, &dev); dev;
 			device_find_next_child(&dev)) {
 		struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
 		int ret;

 		if (chip->chip_addr == chip_addr) {
 			ret = device_probe(dev);
 			debug("found, ret=%d\n", ret);
 			if (ret)
 				return ret;
 			*devp = dev;
 			return 0;
 		}
 	}
 	debug("not found\n");
 	return i2c_bind_driver(bus, chip_addr, offset_len, devp);
 }

 int i2c_get_chip_for_busnum(int busnum, int chip_addr, uint offset_len,
 			    struct udevice **devp)
 {
 	struct udevice *bus;
 	int ret;

 	ret = uclass_get_device_by_seq(UCLASS_I2C, busnum, &bus);
 	if (ret) {
 		debug("Cannot find I2C bus %d\n", busnum);
 		return ret;
 	}
 	ret = i2c_get_chip(bus, chip_addr, offset_len, devp);
 	if (ret) {
 		debug("Cannot find I2C chip %02x on bus %d\n", chip_addr,
 		      busnum);
 		return ret;
 	}

 	return 0;
 }

 int dm_i2c_probe(struct udevice *bus, uint chip_addr, uint chip_flags,
 		 struct udevice **devp)
 {
 	int ret;

 	*devp = NULL;

 	/* First probe that chip */
 	ret = i2c_probe_chip(bus, chip_addr, chip_flags);
 	debug("%s: bus='%s', address %02x, ret=%d\n", __func__, bus->name,
 	      chip_addr, ret);
 	if (ret)
 		return ret;

 	/* The chip was found, see if we have a driver, and probe it */
 	ret = i2c_get_chip(bus, chip_addr, 1, devp);
 	debug("%s:  i2c_get_chip: ret=%d\n", __func__, ret);

 	return ret;
 }

 int dm_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
 {
 	struct dm_i2c_ops *ops = i2c_get_ops(bus);
 	struct dm_i2c_bus *i2c = dev_get_uclass_priv(bus);
 	int ret;

 	/*
 	 * If we have a method, call it. If not then the driver probably wants
 	 * to deal with speed changes on the next transfer. It can easily read
 	 * the current speed from this uclass
 	 */
 	if (ops->set_bus_speed) {
 		ret = ops->set_bus_speed(bus, speed);
 		if (ret)
 			return ret;
 	}
 	i2c->speed_hz = speed;

 	return 0;
 }

 int dm_i2c_get_bus_speed(struct udevice *bus)
 {
 	struct dm_i2c_ops *ops = i2c_get_ops(bus);
 	struct dm_i2c_bus *i2c = dev_get_uclass_priv(bus);

 	if (!ops->get_bus_speed)
 		return i2c->speed_hz;

 	return ops->get_bus_speed(bus);
 }

 int i2c_set_chip_flags(struct udevice *dev, uint flags)
 {
 	struct udevice *bus = dev->parent;
 	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
 	struct dm_i2c_ops *ops = i2c_get_ops(bus);
 	int ret;

 	if (ops->set_flags) {
 		ret = ops->set_flags(dev, flags);
 		if (ret)
 			return ret;
 	}
 	chip->flags = flags;

 	return 0;
 }

 int i2c_get_chip_flags(struct udevice *dev, uint *flagsp)
 {
 	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);

 	*flagsp = chip->flags;

 	return 0;
 }

 int i2c_set_chip_offset_len(struct udevice *dev, uint offset_len)
 {
 	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);

 	if (offset_len > I2C_MAX_OFFSET_LEN)
 		return -EINVAL;
 	chip->offset_len = offset_len;

 	return 0;
 }

 int i2c_get_chip_offset_len(struct udevice *dev)
 {
 	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);

 	return chip->offset_len;
 }

 int i2c_deblock(struct udevice *bus)
 {
 	struct dm_i2c_ops *ops = i2c_get_ops(bus);

 	/*
 	 * We could implement a software deblocking here if we could get
 	 * access to the GPIOs used by I2C, and switch them to GPIO mode
 	 * and then back to I2C. This is somewhat beyond our powers in
 	 * driver model at present, so for now just fail.
 	 *
 	 * See https://patchwork.ozlabs.org/patch/399040/
 	 */
 	if (!ops->deblock)
 		return -ENOSYS;

 	return ops->deblock(bus);
 }

 #if CONFIG_IS_ENABLED(OF_CONTROL)
 int i2c_chip_ofdata_to_platdata(const void *blob, int node,
 				struct dm_i2c_chip *chip)
 {
 	chip->offset_len = fdtdec_get_int(gd->fdt_blob, node,
 					  "u-boot,i2c-offset-len", 1);
 	chip->flags = 0;
 	chip->chip_addr = fdtdec_get_int(gd->fdt_blob, node, "reg", -1);
 	if (chip->chip_addr == -1) {
 		debug("%s: I2C Node '%s' has no 'reg' property\n", __func__,
 		      fdt_get_name(blob, node, NULL));
 		return -EINVAL;
 	}

 	return 0;
 }
 #endif

 static int i2c_post_probe(struct udevice *dev)
 {
 #if CONFIG_IS_ENABLED(OF_CONTROL)
 	struct dm_i2c_bus *i2c = dev_get_uclass_priv(dev);

 	i2c->speed_hz = fdtdec_get_int(gd->fdt_blob, dev_of_offset(dev),
 				     "clock-frequency", 100000);

 	return dm_i2c_set_bus_speed(dev, i2c->speed_hz);
 #else
 	return 0;
 #endif
 }

 static int i2c_child_post_bind(struct udevice *dev)
 {
 #if CONFIG_IS_ENABLED(OF_CONTROL)
 	struct dm_i2c_chip *plat = dev_get_parent_platdata(dev);

 	if (dev_of_offset(dev) == -1)
 		return 0;

 	return i2c_chip_ofdata_to_platdata(gd->fdt_blob, dev_of_offset(dev),
 					   plat);
 #else
 	return 0;
 #endif
 }

 UCLASS_DRIVER(i2c) = {
 	.id		= UCLASS_I2C,
 	.name		= "i2c",
 	.flags		= DM_UC_FLAG_SEQ_ALIAS,
 #if CONFIG_IS_ENABLED(OF_CONTROL)
 	.post_bind	= dm_scan_fdt_dev,
 #endif
 	.post_probe	= i2c_post_probe,
 	.per_device_auto_alloc_size = sizeof(struct dm_i2c_bus),
 	.per_child_platdata_auto_alloc_size = sizeof(struct dm_i2c_chip),
 	.child_post_bind = i2c_child_post_bind,
 };

 UCLASS_DRIVER(i2c_generic) = {
 	.id		= UCLASS_I2C_GENERIC,
 	.name		= "i2c_generic",
 };

 U_BOOT_DRIVER(i2c_generic_chip_drv) = {
 	.name		= "i2c_generic_chip_drv",
 	.id		= UCLASS_I2C_GENERIC,
 };
	/*
	* Copyright (c) 2014 Google, Inc
	*
	* SPDX-License-Identifier: GPL-2.0+
	*/

	#include <common.h>
	#include <dm.h>
	#include <errno.h>
	#include <fdtdec.h>
	#include <i2c.h>
	#include <malloc.h>
	#include <dm/device-internal.h>
	#include <dm/lists.h>

	DECLARE_GLOBAL_DATA_PTR;

	#define I2C_MAX_OFFSET_LEN 4

	/* Useful debugging function */
	void i2c_dump_msgs(struct i2c_msg *msg, int nmsgs)
	{
	int i;

	for (i = 0; i < nmsgs; i++) {
	struct i2c_msg *m = &msg[i];

	printf(" %s %x len=%x", m->flags & I2C_M_RD ? "R" : "W",
	msg->addr, msg->len);
	if (!(m->flags & I2C_M_RD))
	printf(": %x", m->buf[0]);
	printf("\n");
	}
	}

	/**
	* i2c_setup_offset() - Set up a new message with a chip offset
	*
	* @chip: Chip to use
	* @offset: Byte offset within chip
	* @offset_buf: Place to put byte offset
	* @msg: Message buffer
	* @return 0 if OK, -EADDRNOTAVAIL if the offset length is 0. In that case the
	* message is still set up but will not contain an offset.
	*/
	static int i2c_setup_offset(struct dm_i2c_chip *chip, uint offset,
	uint8_t offset_buf[], struct i2c_msg *msg)
	{
	int offset_len;

	msg->addr = chip->chip_addr;
	msg->flags = chip->flags & DM_I2C_CHIP_10BIT ? I2C_M_TEN : 0;
	msg->len = chip->offset_len;
	msg->buf = offset_buf;
	if (!chip->offset_len)
	return -EADDRNOTAVAIL;
	assert(chip->offset_len <= I2C_MAX_OFFSET_LEN);
	offset_len = chip->offset_len;
	while (offset_len--)
	offset_buf++ = offset >> (8 offset_len);

	return 0;
	}

	static int i2c_read_bytewise(struct udevice *dev, uint offset,
	uint8_t *buffer, int len)
	{
	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
	struct udevice *bus = dev_get_parent(dev);
	struct dm_i2c_ops *ops = i2c_get_ops(bus);
	struct i2c_msg msg[2], *ptr;
	uint8_t offset_buf[I2C_MAX_OFFSET_LEN];
	int ret;
	int i;

	for (i = 0; i < len; i++) {
	if (i2c_setup_offset(chip, offset + i, offset_buf, msg))
	return -EINVAL;
	ptr = msg + 1;
	ptr->addr = chip->chip_addr;
	ptr->flags = msg->flags \| I2C_M_RD;
	ptr->len = 1;
	ptr->buf = &buffer[i];
	ptr++;

	ret = ops->xfer(bus, msg, ptr - msg);
	if (ret)
	return ret;
	}

	return 0;
	}

	static int i2c_write_bytewise(struct udevice *dev, uint offset,
	const uint8_t *buffer, int len)
	{
	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
	struct udevice *bus = dev_get_parent(dev);
	struct dm_i2c_ops *ops = i2c_get_ops(bus);
	struct i2c_msg msg[1];
	uint8_t buf[I2C_MAX_OFFSET_LEN + 1];
	int ret;
	int i;

	for (i = 0; i < len; i++) {
	if (i2c_setup_offset(chip, offset + i, buf, msg))
	return -EINVAL;
	buf[msg->len++] = buffer[i];

	ret = ops->xfer(bus, msg, 1);
	if (ret)
	return ret;
	}

	return 0;
	}

	int dm_i2c_read(struct udevice dev, uint offset, uint8_t buffer, int len)
	{
	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
	struct udevice *bus = dev_get_parent(dev);
	struct dm_i2c_ops *ops = i2c_get_ops(bus);
	struct i2c_msg msg[2], *ptr;
	uint8_t offset_buf[I2C_MAX_OFFSET_LEN];
	int msg_count;

	if (!ops->xfer)
	return -ENOSYS;
	if (chip->flags & DM_I2C_CHIP_RD_ADDRESS)
	return i2c_read_bytewise(dev, offset, buffer, len);
	ptr = msg;
	if (!i2c_setup_offset(chip, offset, offset_buf, ptr))
	ptr++;

	if (len) {
	ptr->addr = chip->chip_addr;
	ptr->flags = chip->flags & DM_I2C_CHIP_10BIT ? I2C_M_TEN : 0;
	ptr->flags \|= I2C_M_RD;
	ptr->len = len;
	ptr->buf = buffer;
	ptr++;
	}
	msg_count = ptr - msg;

	return ops->xfer(bus, msg, msg_count);
	}

	int dm_i2c_write(struct udevice dev, uint offset, const uint8_t buffer,
	int len)
	{
	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
	struct udevice *bus = dev_get_parent(dev);
	struct dm_i2c_ops *ops = i2c_get_ops(bus);
	struct i2c_msg msg[1];

	if (!ops->xfer)
	return -ENOSYS;

	if (chip->flags & DM_I2C_CHIP_WR_ADDRESS)
	return i2c_write_bytewise(dev, offset, buffer, len);
	/*
	* The simple approach would be to send two messages here: one to
	* set the offset and one to write the bytes. However some drivers
	* will not be expecting this, and some chips won't like how the
	* driver presents this on the I2C bus.
	*
	* The API does not support separate offset and data. We could extend
	* it with a flag indicating that there is data in the next message
	* that needs to be processed in the same transaction. We could
	* instead add an additional buffer to each message. For now, handle
	* this in the uclass since it isn't clear what the impact on drivers
	* would be with this extra complication. Unfortunately this means
	* copying the message.
	*
	* Use the stack for small messages, malloc() for larger ones. We
	* need to allow space for the offset (up to 4 bytes) and the message
	* itself.
	*/
	if (len < 64) {
	uint8_t buf[I2C_MAX_OFFSET_LEN + len];

	i2c_setup_offset(chip, offset, buf, msg);
	msg->len += len;
	memcpy(buf + chip->offset_len, buffer, len);

	return ops->xfer(bus, msg, 1);
	} else {
	uint8_t *buf;
	int ret;

	buf = malloc(I2C_MAX_OFFSET_LEN + len);
	if (!buf)
	return -ENOMEM;
	i2c_setup_offset(chip, offset, buf, msg);
	msg->len += len;
	memcpy(buf + chip->offset_len, buffer, len);

	ret = ops->xfer(bus, msg, 1);
	free(buf);
	return ret;
	}
	}

	int dm_i2c_xfer(struct udevice dev, struct i2c_msg msg, int nmsgs)
	{
	struct udevice *bus = dev_get_parent(dev);
	struct dm_i2c_ops *ops = i2c_get_ops(bus);

	if (!ops->xfer)
	return -ENOSYS;

	return ops->xfer(bus, msg, nmsgs);
	}

	int dm_i2c_reg_read(struct udevice *dev, uint offset)
	{
	uint8_t val;
	int ret;

	ret = dm_i2c_read(dev, offset, &val, 1);
	if (ret < 0)
	return ret;

	return val;
	}

	int dm_i2c_reg_write(struct udevice *dev, uint offset, uint value)
	{
	uint8_t val = value;

	return dm_i2c_write(dev, offset, &val, 1);
	}

	/**
	* i2c_probe_chip() - probe for a chip on a bus
	*
	* @bus: Bus to probe
	* @chip_addr: Chip address to probe
	* @flags: Flags for the chip
	* @return 0 if found, -ENOSYS if the driver is invalid, -EREMOTEIO if the chip
	* does not respond to probe
	*/
	static int i2c_probe_chip(struct udevice *bus, uint chip_addr,
	enum dm_i2c_chip_flags chip_flags)
	{
	struct dm_i2c_ops *ops = i2c_get_ops(bus);
	struct i2c_msg msg[1];
	int ret;

	if (ops->probe_chip) {
	ret = ops->probe_chip(bus, chip_addr, chip_flags);
	if (!ret \|\| ret != -ENOSYS)
	return ret;
	}

	if (!ops->xfer)
	return -ENOSYS;

	/* Probe with a zero-length message */
	msg->addr = chip_addr;
	msg->flags = chip_flags & DM_I2C_CHIP_10BIT ? I2C_M_TEN : 0;
	msg->len = 0;
	msg->buf = NULL;

	return ops->xfer(bus, msg, 1);
	}

	static int i2c_bind_driver(struct udevice *bus, uint chip_addr, uint offset_len,
	struct udevice **devp)
	{
	struct dm_i2c_chip *chip;
	char name[30], *str;
	struct udevice *dev;
	int ret;

	snprintf(name, sizeof(name), "generic_%x", chip_addr);
	str = strdup(name);
	if (!str)
	return -ENOMEM;
	ret = device_bind_driver(bus, "i2c_generic_chip_drv", str, &dev);
	debug("%s: device_bind_driver: ret=%d\n", __func__, ret);
	if (ret)
	goto err_bind;

	/* Tell the device what we know about it */
	chip = dev_get_parent_platdata(dev);
	chip->chip_addr = chip_addr;
	chip->offset_len = offset_len;
	ret = device_probe(dev);
	debug("%s: device_probe: ret=%d\n", __func__, ret);
	if (ret)
	goto err_probe;

	*devp = dev;
	return 0;

	err_probe:
	/*
	* If the device failed to probe, unbind it. There is nothing there
	* on the bus so we don't want to leave it lying around
	*/
	device_unbind(dev);
	err_bind:
	free(str);
	return ret;
	}

	int i2c_get_chip(struct udevice *bus, uint chip_addr, uint offset_len,
	struct udevice **devp)
	{
	struct udevice *dev;

	debug("%s: Searching bus '%s' for address %02x: ", __func__,
	bus->name, chip_addr);
	for (device_find_first_child(bus, &dev); dev;
	device_find_next_child(&dev)) {
	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
	int ret;

	if (chip->chip_addr == chip_addr) {
	ret = device_probe(dev);
	debug("found, ret=%d\n", ret);
	if (ret)
	return ret;
	*devp = dev;
	return 0;
	}
	}
	debug("not found\n");
	return i2c_bind_driver(bus, chip_addr, offset_len, devp);
	}

	int i2c_get_chip_for_busnum(int busnum, int chip_addr, uint offset_len,
	struct udevice **devp)
	{
	struct udevice *bus;
	int ret;

	ret = uclass_get_device_by_seq(UCLASS_I2C, busnum, &bus);
	if (ret) {
	debug("Cannot find I2C bus %d\n", busnum);
	return ret;
	}
	ret = i2c_get_chip(bus, chip_addr, offset_len, devp);
	if (ret) {
	debug("Cannot find I2C chip %02x on bus %d\n", chip_addr,
	busnum);
	return ret;
	}

	return 0;
	}

	int dm_i2c_probe(struct udevice *bus, uint chip_addr, uint chip_flags,
	struct udevice **devp)
	{
	int ret;

	*devp = NULL;

	/* First probe that chip */
	ret = i2c_probe_chip(bus, chip_addr, chip_flags);
	debug("%s: bus='%s', address %02x, ret=%d\n", __func__, bus->name,
	chip_addr, ret);
	if (ret)
	return ret;

	/* The chip was found, see if we have a driver, and probe it */
	ret = i2c_get_chip(bus, chip_addr, 1, devp);
	debug("%s: i2c_get_chip: ret=%d\n", __func__, ret);

	return ret;
	}

	int dm_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
	{
	struct dm_i2c_ops *ops = i2c_get_ops(bus);
	struct dm_i2c_bus *i2c = dev_get_uclass_priv(bus);
	int ret;

	/*
	* If we have a method, call it. If not then the driver probably wants
	* to deal with speed changes on the next transfer. It can easily read
	* the current speed from this uclass
	*/
	if (ops->set_bus_speed) {
	ret = ops->set_bus_speed(bus, speed);
	if (ret)
	return ret;
	}
	i2c->speed_hz = speed;

	return 0;
	}

	int dm_i2c_get_bus_speed(struct udevice *bus)
	{
	struct dm_i2c_ops *ops = i2c_get_ops(bus);
	struct dm_i2c_bus *i2c = dev_get_uclass_priv(bus);

	if (!ops->get_bus_speed)
	return i2c->speed_hz;

	return ops->get_bus_speed(bus);
	}

	int i2c_set_chip_flags(struct udevice *dev, uint flags)
	{
	struct udevice *bus = dev->parent;
	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
	struct dm_i2c_ops *ops = i2c_get_ops(bus);
	int ret;

	if (ops->set_flags) {
	ret = ops->set_flags(dev, flags);
	if (ret)
	return ret;
	}
	chip->flags = flags;

	return 0;
	}

	int i2c_get_chip_flags(struct udevice dev, uint flagsp)
	{
	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);

	*flagsp = chip->flags;

	return 0;
	}

	int i2c_set_chip_offset_len(struct udevice *dev, uint offset_len)
	{
	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);

	if (offset_len > I2C_MAX_OFFSET_LEN)
	return -EINVAL;
	chip->offset_len = offset_len;

	return 0;
	}

	int i2c_get_chip_offset_len(struct udevice *dev)
	{
	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);

	return chip->offset_len;
	}

	int i2c_deblock(struct udevice *bus)
	{
	struct dm_i2c_ops *ops = i2c_get_ops(bus);

	/*
	* We could implement a software deblocking here if we could get
	* access to the GPIOs used by I2C, and switch them to GPIO mode
	* and then back to I2C. This is somewhat beyond our powers in
	* driver model at present, so for now just fail.
	*
	* See https://patchwork.ozlabs.org/patch/399040/
	*/
	if (!ops->deblock)
	return -ENOSYS;

	return ops->deblock(bus);
	}

	#if CONFIG_IS_ENABLED(OF_CONTROL)
	int i2c_chip_ofdata_to_platdata(const void *blob, int node,
	struct dm_i2c_chip *chip)
	{
	chip->offset_len = fdtdec_get_int(gd->fdt_blob, node,
	"u-boot,i2c-offset-len", 1);
	chip->flags = 0;
	chip->chip_addr = fdtdec_get_int(gd->fdt_blob, node, "reg", -1);
	if (chip->chip_addr == -1) {
	debug("%s: I2C Node '%s' has no 'reg' property\n", __func__,
	fdt_get_name(blob, node, NULL));
	return -EINVAL;
	}

	return 0;
	}
	#endif

	static int i2c_post_probe(struct udevice *dev)
	{
	#if CONFIG_IS_ENABLED(OF_CONTROL)
	struct dm_i2c_bus *i2c = dev_get_uclass_priv(dev);

	i2c->speed_hz = fdtdec_get_int(gd->fdt_blob, dev_of_offset(dev),
	"clock-frequency", 100000);

	return dm_i2c_set_bus_speed(dev, i2c->speed_hz);
	#else
	return 0;
	#endif
	}

	static int i2c_child_post_bind(struct udevice *dev)
	{
	#if CONFIG_IS_ENABLED(OF_CONTROL)
	struct dm_i2c_chip *plat = dev_get_parent_platdata(dev);

	if (dev_of_offset(dev) == -1)
	return 0;

	return i2c_chip_ofdata_to_platdata(gd->fdt_blob, dev_of_offset(dev),
	plat);
	#else
	return 0;
	#endif
	}

	UCLASS_DRIVER(i2c) = {
	.id = UCLASS_I2C,
	.name = "i2c",
	.flags = DM_UC_FLAG_SEQ_ALIAS,
	#if CONFIG_IS_ENABLED(OF_CONTROL)
	.post_bind = dm_scan_fdt_dev,
	#endif
	.post_probe = i2c_post_probe,
	.per_device_auto_alloc_size = sizeof(struct dm_i2c_bus),
	.per_child_platdata_auto_alloc_size = sizeof(struct dm_i2c_chip),
	.child_post_bind = i2c_child_post_bind,
	};

	UCLASS_DRIVER(i2c_generic) = {
	.id = UCLASS_I2C_GENERIC,
	.name = "i2c_generic",
	};

	U_BOOT_DRIVER(i2c_generic_chip_drv) = {
	.name = "i2c_generic_chip_drv",
	.id = UCLASS_I2C_GENERIC,
	};