Initial import

1 files changed, 2964 insertions, 0 deletions

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
new file mode 100644
index 000000000..987c12443
--- /dev/null
+++ b/drivers/i2c/i2c-core.c
@@ -0,0 +1,2964 @@
+/* i2c-core.c - a device driver for the iic-bus interface		     */
+/* ------------------------------------------------------------------------- */
+/*   Copyright (C) 1995-99 Simon G. Vogl
+
+    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.			     */
+/* ------------------------------------------------------------------------- */
+
+/* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>.
+   All SMBus-related things are written by Frodo Looijaard <frodol@dds.nl>
+   SMBus 2.0 support by Mark Studebaker <mdsxyz123@yahoo.com> and
+   Jean Delvare <jdelvare@suse.de>
+   Mux support by Rodolfo Giometti <giometti@enneenne.com> and
+   Michael Lawnick <michael.lawnick.ext@nsn.com>
+   OF support is copyright (c) 2008 Jochen Friedrich <jochen@scram.de>
+   (based on a previous patch from Jon Smirl <jonsmirl@gmail.com>) and
+   (c) 2013  Wolfram Sang <wsa@the-dreams.de>
+   I2C ACPI code Copyright (C) 2014 Intel Corp
+   Author: Lan Tianyu <tianyu.lan@intel.com>
+   I2C slave support (c) 2014 by Wolfram Sang <wsa@sang-engineering.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/gpio.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/idr.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_irq.h>
+#include <linux/clk/clk-conf.h>
+#include <linux/completion.h>
+#include <linux/hardirq.h>
+#include <linux/irqflags.h>
+#include <linux/rwsem.h>
+#include <linux/pm_runtime.h>
+#include <linux/pm_domain.h>
+#include <linux/acpi.h>
+#include <linux/jump_label.h>
+#include <asm/uaccess.h>
+#include <linux/err.h>
+
+#include "i2c-core.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/i2c.h>
+
+/* core_lock protects i2c_adapter_idr, and guarantees
+   that device detection, deletion of detected devices, and attach_adapter
+   calls are serialized */
+static DEFINE_MUTEX(core_lock);
+static DEFINE_IDR(i2c_adapter_idr);
+
+static struct device_type i2c_client_type;
+static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
+
+static struct static_key i2c_trace_msg = STATIC_KEY_INIT_FALSE;
+
+void i2c_transfer_trace_reg(void)
+{
+	static_key_slow_inc(&i2c_trace_msg);
+}
+
+void i2c_transfer_trace_unreg(void)
+{
+	static_key_slow_dec(&i2c_trace_msg);
+}
+
+#if defined(CONFIG_ACPI)
+struct acpi_i2c_handler_data {
+	struct acpi_connection_info info;
+	struct i2c_adapter *adapter;
+};
+
+struct gsb_buffer {
+	u8	status;
+	u8	len;
+	union {
+		u16	wdata;
+		u8	bdata;
+		u8	data[0];
+	};
+} __packed;
+
+static int acpi_i2c_add_resource(struct acpi_resource *ares, void *data)
+{
+	struct i2c_board_info *info = data;
+
+	if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
+		struct acpi_resource_i2c_serialbus *sb;
+
+		sb = &ares->data.i2c_serial_bus;
+		if (!info->addr && sb->type == ACPI_RESOURCE_SERIAL_TYPE_I2C) {
+			info->addr = sb->slave_address;
+			if (sb->access_mode == ACPI_I2C_10BIT_MODE)
+				info->flags |= I2C_CLIENT_TEN;
+		}
+	} else if (info->irq < 0) {
+		struct resource r;
+
+		if (acpi_dev_resource_interrupt(ares, 0, &r))
+			info->irq = r.start;
+	}
+
+	/* Tell the ACPI core to skip this resource */
+	return 1;
+}
+
+static acpi_status acpi_i2c_add_device(acpi_handle handle, u32 level,
+				       void *data, void **return_value)
+{
+	struct i2c_adapter *adapter = data;
+	struct list_head resource_list;
+	struct i2c_board_info info;
+	struct acpi_device *adev;
+	int ret;
+
+	if (acpi_bus_get_device(handle, &adev))
+		return AE_OK;
+	if (acpi_bus_get_status(adev) || !adev->status.present)
+		return AE_OK;
+
+	memset(&info, 0, sizeof(info));
+	info.fwnode = acpi_fwnode_handle(adev);
+	info.irq = -1;
+
+	INIT_LIST_HEAD(&resource_list);
+	ret = acpi_dev_get_resources(adev, &resource_list,
+				     acpi_i2c_add_resource, &info);
+	acpi_dev_free_resource_list(&resource_list);
+
+	if (ret < 0 || !info.addr)
+		return AE_OK;
+
+	adev->power.flags.ignore_parent = true;
+	strlcpy(info.type, dev_name(&adev->dev), sizeof(info.type));
+	if (!i2c_new_device(adapter, &info)) {
+		adev->power.flags.ignore_parent = false;
+		dev_err(&adapter->dev,
+			"failed to add I2C device %s from ACPI\n",
+			dev_name(&adev->dev));
+	}
+
+	return AE_OK;
+}
+
+/**
+ * acpi_i2c_register_devices - enumerate I2C slave devices behind adapter
+ * @adap: pointer to adapter
+ *
+ * Enumerate all I2C slave devices behind this adapter by walking the ACPI
+ * namespace. When a device is found it will be added to the Linux device
+ * model and bound to the corresponding ACPI handle.
+ */
+static void acpi_i2c_register_devices(struct i2c_adapter *adap)
+{
+	acpi_handle handle;
+	acpi_status status;
+
+	if (!adap->dev.parent)
+		return;
+
+	handle = ACPI_HANDLE(adap->dev.parent);
+	if (!handle)
+		return;
+
+	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
+				     acpi_i2c_add_device, NULL,
+				     adap, NULL);
+	if (ACPI_FAILURE(status))
+		dev_warn(&adap->dev, "failed to enumerate I2C slaves\n");
+}
+
+#else /* CONFIG_ACPI */
+static inline void acpi_i2c_register_devices(struct i2c_adapter *adap) { }
+#endif /* CONFIG_ACPI */
+
+#ifdef CONFIG_ACPI_I2C_OPREGION
+static int acpi_gsb_i2c_read_bytes(struct i2c_client *client,
+		u8 cmd, u8 *data, u8 data_len)
+{
+
+	struct i2c_msg msgs[2];
+	int ret;
+	u8 *buffer;
+
+	buffer = kzalloc(data_len, GFP_KERNEL);
+	if (!buffer)
+		return AE_NO_MEMORY;
+
+	msgs[0].addr = client->addr;
+	msgs[0].flags = client->flags;
+	msgs[0].len = 1;
+	msgs[0].buf = &cmd;
+
+	msgs[1].addr = client->addr;
+	msgs[1].flags = client->flags | I2C_M_RD;
+	msgs[1].len = data_len;
+	msgs[1].buf = buffer;
+
+	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (ret < 0)
+		dev_err(&client->adapter->dev, "i2c read failed\n");
+	else
+		memcpy(data, buffer, data_len);
+
+	kfree(buffer);
+	return ret;
+}
+
+static int acpi_gsb_i2c_write_bytes(struct i2c_client *client,
+		u8 cmd, u8 *data, u8 data_len)
+{
+
+	struct i2c_msg msgs[1];
+	u8 *buffer;
+	int ret = AE_OK;
+
+	buffer = kzalloc(data_len + 1, GFP_KERNEL);
+	if (!buffer)
+		return AE_NO_MEMORY;
+
+	buffer[0] = cmd;
+	memcpy(buffer + 1, data, data_len);
+
+	msgs[0].addr = client->addr;
+	msgs[0].flags = client->flags;
+	msgs[0].len = data_len + 1;
+	msgs[0].buf = buffer;
+
+	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (ret < 0)
+		dev_err(&client->adapter->dev, "i2c write failed\n");
+
+	kfree(buffer);
+	return ret;
+}
+
+static acpi_status
+acpi_i2c_space_handler(u32 function, acpi_physical_address command,
+			u32 bits, u64 *value64,
+			void *handler_context, void *region_context)
+{
+	struct gsb_buffer *gsb = (struct gsb_buffer *)value64;
+	struct acpi_i2c_handler_data *data = handler_context;
+	struct acpi_connection_info *info = &data->info;
+	struct acpi_resource_i2c_serialbus *sb;
+	struct i2c_adapter *adapter = data->adapter;
+	struct i2c_client client;
+	struct acpi_resource *ares;
+	u32 accessor_type = function >> 16;
+	u8 action = function & ACPI_IO_MASK;
+	acpi_status ret;
+	int status;
+
+	ret = acpi_buffer_to_resource(info->connection, info->length, &ares);
+	if (ACPI_FAILURE(ret))
+		return ret;
+
+	if (!value64 || ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS) {
+		ret = AE_BAD_PARAMETER;
+		goto err;
+	}
+
+	sb = &ares->data.i2c_serial_bus;
+	if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_I2C) {
+		ret = AE_BAD_PARAMETER;
+		goto err;
+	}
+
+	memset(&client, 0, sizeof(client));
+	client.adapter = adapter;
+	client.addr = sb->slave_address;
+	client.flags = 0;
+
+	if (sb->access_mode == ACPI_I2C_10BIT_MODE)
+		client.flags |= I2C_CLIENT_TEN;
+
+	switch (accessor_type) {
+	case ACPI_GSB_ACCESS_ATTRIB_SEND_RCV:
+		if (action == ACPI_READ) {
+			status = i2c_smbus_read_byte(&client);
+			if (status >= 0) {
+				gsb->bdata = status;
+				status = 0;
+			}
+		} else {
+			status = i2c_smbus_write_byte(&client, gsb->bdata);
+		}
+		break;
+
+	case ACPI_GSB_ACCESS_ATTRIB_BYTE:
+		if (action == ACPI_READ) {
+			status = i2c_smbus_read_byte_data(&client, command);
+			if (status >= 0) {
+				gsb->bdata = status;
+				status = 0;
+			}
+		} else {
+			status = i2c_smbus_write_byte_data(&client, command,
+					gsb->bdata);
+		}
+		break;
+
+	case ACPI_GSB_ACCESS_ATTRIB_WORD:
+		if (action == ACPI_READ) {
+			status = i2c_smbus_read_word_data(&client, command);
+			if (status >= 0) {
+				gsb->wdata = status;
+				status = 0;
+			}
+		} else {
+			status = i2c_smbus_write_word_data(&client, command,
+					gsb->wdata);
+		}
+		break;
+
+	case ACPI_GSB_ACCESS_ATTRIB_BLOCK:
+		if (action == ACPI_READ) {
+			status = i2c_smbus_read_block_data(&client, command,
+					gsb->data);
+			if (status >= 0) {
+				gsb->len = status;
+				status = 0;
+			}
+		} else {
+			status = i2c_smbus_write_block_data(&client, command,
+					gsb->len, gsb->data);
+		}
+		break;
+
+	case ACPI_GSB_ACCESS_ATTRIB_MULTIBYTE:
+		if (action == ACPI_READ) {
+			status = acpi_gsb_i2c_read_bytes(&client, command,
+					gsb->data, info->access_length);
+			if (status > 0)
+				status = 0;
+		} else {
+			status = acpi_gsb_i2c_write_bytes(&client, command,
+					gsb->data, info->access_length);
+		}
+		break;
+
+	default:
+		pr_info("protocol(0x%02x) is not supported.\n", accessor_type);
+		ret = AE_BAD_PARAMETER;
+		goto err;
+	}
+
+	gsb->status = status;
+
+ err:
+	ACPI_FREE(ares);
+	return ret;
+}
+
+
+static int acpi_i2c_install_space_handler(struct i2c_adapter *adapter)
+{
+	acpi_handle handle;
+	struct acpi_i2c_handler_data *data;
+	acpi_status status;
+
+	if (!adapter->dev.parent)
+		return -ENODEV;
+
+	handle = ACPI_HANDLE(adapter->dev.parent);
+
+	if (!handle)
+		return -ENODEV;
+
+	data = kzalloc(sizeof(struct acpi_i2c_handler_data),
+			    GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->adapter = adapter;
+	status = acpi_bus_attach_private_data(handle, (void *)data);
+	if (ACPI_FAILURE(status)) {
+		kfree(data);
+		return -ENOMEM;
+	}
+
+	status = acpi_install_address_space_handler(handle,
+				ACPI_ADR_SPACE_GSBUS,
+				&acpi_i2c_space_handler,
+				NULL,
+				data);
+	if (ACPI_FAILURE(status)) {
+		dev_err(&adapter->dev, "Error installing i2c space handler\n");
+		acpi_bus_detach_private_data(handle);
+		kfree(data);
+		return -ENOMEM;
+	}
+
+	acpi_walk_dep_device_list(handle);
+	return 0;
+}
+
+static void acpi_i2c_remove_space_handler(struct i2c_adapter *adapter)
+{
+	acpi_handle handle;
+	struct acpi_i2c_handler_data *data;
+	acpi_status status;
+
+	if (!adapter->dev.parent)
+		return;
+
+	handle = ACPI_HANDLE(adapter->dev.parent);
+
+	if (!handle)
+		return;
+
+	acpi_remove_address_space_handler(handle,
+				ACPI_ADR_SPACE_GSBUS,
+				&acpi_i2c_space_handler);
+
+	status = acpi_bus_get_private_data(handle, (void **)&data);
+	if (ACPI_SUCCESS(status))
+		kfree(data);
+
+	acpi_bus_detach_private_data(handle);
+}
+#else /* CONFIG_ACPI_I2C_OPREGION */
+static inline void acpi_i2c_remove_space_handler(struct i2c_adapter *adapter)
+{ }
+
+static inline int acpi_i2c_install_space_handler(struct i2c_adapter *adapter)
+{ return 0; }
+#endif /* CONFIG_ACPI_I2C_OPREGION */
+
+/* ------------------------------------------------------------------------- */
+
+static const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
+						const struct i2c_client *client)
+{
+	while (id->name[0]) {
+		if (strcmp(client->name, id->name) == 0)
+			return id;
+		id++;
+	}
+	return NULL;
+}
+
+static int i2c_device_match(struct device *dev, struct device_driver *drv)
+{
+	struct i2c_client	*client = i2c_verify_client(dev);
+	struct i2c_driver	*driver;
+
+	if (!client)
+		return 0;
+
+	/* Attempt an OF style match */
+	if (of_driver_match_device(dev, drv))
+		return 1;
+
+	/* Then ACPI style match */
+	if (acpi_driver_match_device(dev, drv))
+		return 1;
+
+	driver = to_i2c_driver(drv);
+	/* match on an id table if there is one */
+	if (driver->id_table)
+		return i2c_match_id(driver->id_table, client) != NULL;
+
+	return 0;
+}
+
+
+/* uevent helps with hotplug: modprobe -q $(MODALIAS) */
+static int i2c_device_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+	struct i2c_client	*client = to_i2c_client(dev);
+	int rc;
+
+	rc = acpi_device_uevent_modalias(dev, env);
+	if (rc != -ENODEV)
+		return rc;
+
+	if (add_uevent_var(env, "MODALIAS=%s%s",
+			   I2C_MODULE_PREFIX, client->name))
+		return -ENOMEM;
+	dev_dbg(dev, "uevent\n");
+	return 0;
+}
+
+/* i2c bus recovery routines */
+static int get_scl_gpio_value(struct i2c_adapter *adap)
+{
+	return gpio_get_value(adap->bus_recovery_info->scl_gpio);
+}
+
+static void set_scl_gpio_value(struct i2c_adapter *adap, int val)
+{
+	gpio_set_value(adap->bus_recovery_info->scl_gpio, val);
+}
+
+static int get_sda_gpio_value(struct i2c_adapter *adap)
+{
+	return gpio_get_value(adap->bus_recovery_info->sda_gpio);
+}
+
+static int i2c_get_gpios_for_recovery(struct i2c_adapter *adap)
+{
+	struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
+	struct device *dev = &adap->dev;
+	int ret = 0;
+
+	ret = gpio_request_one(bri->scl_gpio, GPIOF_OPEN_DRAIN |
+			GPIOF_OUT_INIT_HIGH, "i2c-scl");
+	if (ret) {
+		dev_warn(dev, "Can't get SCL gpio: %d\n", bri->scl_gpio);
+		return ret;
+	}
+
+	if (bri->get_sda) {
+		if (gpio_request_one(bri->sda_gpio, GPIOF_IN, "i2c-sda")) {
+			/* work without SDA polling */
+			dev_warn(dev, "Can't get SDA gpio: %d. Not using SDA polling\n",
+					bri->sda_gpio);
+			bri->get_sda = NULL;
+		}
+	}
+
+	return ret;
+}
+
+static void i2c_put_gpios_for_recovery(struct i2c_adapter *adap)
+{
+	struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
+
+	if (bri->get_sda)
+		gpio_free(bri->sda_gpio);
+
+	gpio_free(bri->scl_gpio);
+}
+
+/*
+ * We are generating clock pulses. ndelay() determines durating of clk pulses.
+ * We will generate clock with rate 100 KHz and so duration of both clock levels
+ * is: delay in ns = (10^6 / 100) / 2
+ */
+#define RECOVERY_NDELAY		5000
+#define RECOVERY_CLK_CNT	9
+
+static int i2c_generic_recovery(struct i2c_adapter *adap)
+{
+	struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
+	int i = 0, val = 1, ret = 0;
+
+	if (bri->prepare_recovery)
+		bri->prepare_recovery(adap);
+
+	/*
+	 * By this time SCL is high, as we need to give 9 falling-rising edges
+	 */
+	while (i++ < RECOVERY_CLK_CNT * 2) {
+		if (val) {
+			/* Break if SDA is high */
+			if (bri->get_sda && bri->get_sda(adap))
+					break;
+			/* SCL shouldn't be low here */
+			if (!bri->get_scl(adap)) {
+				dev_err(&adap->dev,
+					"SCL is stuck low, exit recovery\n");
+				ret = -EBUSY;
+				break;
+			}
+		}
+
+		val = !val;
+		bri->set_scl(adap, val);
+		ndelay(RECOVERY_NDELAY);
+	}
+
+	if (bri->unprepare_recovery)
+		bri->unprepare_recovery(adap);
+
+	return ret;
+}
+
+int i2c_generic_scl_recovery(struct i2c_adapter *adap)
+{
+	adap->bus_recovery_info->set_scl(adap, 1);
+	return i2c_generic_recovery(adap);
+}
+EXPORT_SYMBOL_GPL(i2c_generic_scl_recovery);
+
+int i2c_generic_gpio_recovery(struct i2c_adapter *adap)
+{
+	int ret;
+
+	ret = i2c_get_gpios_for_recovery(adap);
+	if (ret)
+		return ret;
+
+	ret = i2c_generic_recovery(adap);
+	i2c_put_gpios_for_recovery(adap);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(i2c_generic_gpio_recovery);
+
+int i2c_recover_bus(struct i2c_adapter *adap)
+{
+	if (!adap->bus_recovery_info)
+		return -EOPNOTSUPP;
+
+	dev_dbg(&adap->dev, "Trying i2c bus recovery\n");
+	return adap->bus_recovery_info->recover_bus(adap);
+}
+EXPORT_SYMBOL_GPL(i2c_recover_bus);
+
+static int i2c_device_probe(struct device *dev)
+{
+	struct i2c_client	*client = i2c_verify_client(dev);
+	struct i2c_driver	*driver;
+	int status;
+
+	if (!client)
+		return 0;
+
+	if (!client->irq && dev->of_node) {
+		int irq = of_irq_get(dev->of_node, 0);
+
+		if (irq == -EPROBE_DEFER)
+			return irq;
+		if (irq < 0)
+			irq = 0;
+
+		client->irq = irq;
+	}
+
+	driver = to_i2c_driver(dev->driver);
+	if (!driver->probe || !driver->id_table)
+		return -ENODEV;
+
+	if (!device_can_wakeup(&client->dev))
+		device_init_wakeup(&client->dev,
+					client->flags & I2C_CLIENT_WAKE);
+	dev_dbg(dev, "probe\n");
+
+	status = of_clk_set_defaults(dev->of_node, false);
+	if (status < 0)
+		return status;
+
+	status = dev_pm_domain_attach(&client->dev, true);
+	if (status != -EPROBE_DEFER) {
+		status = driver->probe(client, i2c_match_id(driver->id_table,
+					client));
+		if (status)
+			dev_pm_domain_detach(&client->dev, true);
+	}
+
+	return status;
+}
+
+static int i2c_device_remove(struct device *dev)
+{
+	struct i2c_client	*client = i2c_verify_client(dev);
+	struct i2c_driver	*driver;
+	int status = 0;
+
+	if (!client || !dev->driver)
+		return 0;
+
+	driver = to_i2c_driver(dev->driver);
+	if (driver->remove) {
+		dev_dbg(dev, "remove\n");
+		status = driver->remove(client);
+	}
+
+	dev_pm_domain_detach(&client->dev, true);
+	return status;
+}
+
+static void i2c_device_shutdown(struct device *dev)
+{
+	struct i2c_client *client = i2c_verify_client(dev);
+	struct i2c_driver *driver;
+
+	if (!client || !dev->driver)
+		return;
+	driver = to_i2c_driver(dev->driver);
+	if (driver->shutdown)
+		driver->shutdown(client);
+}
+
+static void i2c_client_dev_release(struct device *dev)
+{
+	kfree(to_i2c_client(dev));
+}
+
+static ssize_t
+show_name(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%s\n", dev->type == &i2c_client_type ?
+		       to_i2c_client(dev)->name : to_i2c_adapter(dev)->name);
+}
+static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
+
+static ssize_t
+show_modalias(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	int len;
+
+	len = acpi_device_modalias(dev, buf, PAGE_SIZE -1);
+	if (len != -ENODEV)
+		return len;
+
+	return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name);
+}
+static DEVICE_ATTR(modalias, S_IRUGO, show_modalias, NULL);
+
+static struct attribute *i2c_dev_attrs[] = {
+	&dev_attr_name.attr,
+	/* modalias helps coldplug:  modprobe $(cat .../modalias) */
+	&dev_attr_modalias.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(i2c_dev);
+
+struct bus_type i2c_bus_type = {
+	.name		= "i2c",
+	.match		= i2c_device_match,
+	.probe		= i2c_device_probe,
+	.remove		= i2c_device_remove,
+	.shutdown	= i2c_device_shutdown,
+};
+EXPORT_SYMBOL_GPL(i2c_bus_type);
+
+static struct device_type i2c_client_type = {
+	.groups		= i2c_dev_groups,
+	.uevent		= i2c_device_uevent,
+	.release	= i2c_client_dev_release,
+};
+
+
+/**
+ * i2c_verify_client - return parameter as i2c_client, or NULL
+ * @dev: device, probably from some driver model iterator
+ *
+ * When traversing the driver model tree, perhaps using driver model
+ * iterators like @device_for_each_child(), you can't assume very much
+ * about the nodes you find.  Use this function to avoid oopses caused
+ * by wrongly treating some non-I2C device as an i2c_client.
+ */
+struct i2c_client *i2c_verify_client(struct device *dev)
+{
+	return (dev->type == &i2c_client_type)
+			? to_i2c_client(dev)
+			: NULL;
+}
+EXPORT_SYMBOL(i2c_verify_client);
+
+
+/* This is a permissive address validity check, I2C address map constraints
+ * are purposely not enforced, except for the general call address. */
+static int i2c_check_client_addr_validity(const struct i2c_client *client)
+{
+	if (client->flags & I2C_CLIENT_TEN) {
+		/* 10-bit address, all values are valid */
+		if (client->addr > 0x3ff)
+			return -EINVAL;
+	} else {
+		/* 7-bit address, reject the general call address */
+		if (client->addr == 0x00 || client->addr > 0x7f)
+			return -EINVAL;
+	}
+	return 0;
+}
+
+/* And this is a strict address validity check, used when probing. If a
+ * device uses a reserved address, then it shouldn't be probed. 7-bit
+ * addressing is assumed, 10-bit address devices are rare and should be
+ * explicitly enumerated. */
+static int i2c_check_addr_validity(unsigned short addr)
+{
+	/*
+	 * Reserved addresses per I2C specification:
+	 *  0x00       General call address / START byte
+	 *  0x01       CBUS address
+	 *  0x02       Reserved for different bus format
+	 *  0x03       Reserved for future purposes
+	 *  0x04-0x07  Hs-mode master code
+	 *  0x78-0x7b  10-bit slave addressing
+	 *  0x7c-0x7f  Reserved for future purposes
+	 */
+	if (addr < 0x08 || addr > 0x77)
+		return -EINVAL;
+	return 0;
+}
+
+static int __i2c_check_addr_busy(struct device *dev, void *addrp)
+{
+	struct i2c_client	*client = i2c_verify_client(dev);
+	int			addr = *(int *)addrp;
+
+	if (client && client->addr == addr)
+		return -EBUSY;
+	return 0;
+}
+
+/* walk up mux tree */
+static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr)
+{
+	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
+	int result;
+
+	result = device_for_each_child(&adapter->dev, &addr,
+					__i2c_check_addr_busy);
+
+	if (!result && parent)
+		result = i2c_check_mux_parents(parent, addr);
+
+	return result;
+}
+
+/* recurse down mux tree */
+static int i2c_check_mux_children(struct device *dev, void *addrp)
+{
+	int result;
+
+	if (dev->type == &i2c_adapter_type)
+		result = device_for_each_child(dev, addrp,
+						i2c_check_mux_children);
+	else
+		result = __i2c_check_addr_busy(dev, addrp);
+
+	return result;
+}
+
+static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr)
+{
+	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
+	int result = 0;
+
+	if (parent)
+		result = i2c_check_mux_parents(parent, addr);
+
+	if (!result)
+		result = device_for_each_child(&adapter->dev, &addr,
+						i2c_check_mux_children);
+
+	return result;
+}
+
+/**
+ * i2c_lock_adapter - Get exclusive access to an I2C bus segment
+ * @adapter: Target I2C bus segment
+ */
+void i2c_lock_adapter(struct i2c_adapter *adapter)
+{
+	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
+
+	if (parent)
+		i2c_lock_adapter(parent);
+	else
+		rt_mutex_lock(&adapter->bus_lock);
+}
+EXPORT_SYMBOL_GPL(i2c_lock_adapter);
+
+/**
+ * i2c_trylock_adapter - Try to get exclusive access to an I2C bus segment
+ * @adapter: Target I2C bus segment
+ */
+static int i2c_trylock_adapter(struct i2c_adapter *adapter)
+{
+	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
+
+	if (parent)
+		return i2c_trylock_adapter(parent);
+	else
+		return rt_mutex_trylock(&adapter->bus_lock);
+}
+
+/**
+ * i2c_unlock_adapter - Release exclusive access to an I2C bus segment
+ * @adapter: Target I2C bus segment
+ */
+void i2c_unlock_adapter(struct i2c_adapter *adapter)
+{
+	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
+
+	if (parent)
+		i2c_unlock_adapter(parent);
+	else
+		rt_mutex_unlock(&adapter->bus_lock);
+}
+EXPORT_SYMBOL_GPL(i2c_unlock_adapter);
+
+static void i2c_dev_set_name(struct i2c_adapter *adap,
+			     struct i2c_client *client)
+{
+	struct acpi_device *adev = ACPI_COMPANION(&client->dev);
+
+	if (adev) {
+		dev_set_name(&client->dev, "i2c-%s", acpi_dev_name(adev));
+		return;
+	}
+
+	/* For 10-bit clients, add an arbitrary offset to avoid collisions */
+	dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap),
+		     client->addr | ((client->flags & I2C_CLIENT_TEN)
+				     ? 0xa000 : 0));
+}
+
+/**
+ * i2c_new_device - instantiate an i2c device
+ * @adap: the adapter managing the device
+ * @info: describes one I2C device; bus_num is ignored
+ * Context: can sleep
+ *
+ * Create an i2c device. Binding is handled through driver model
+ * probe()/remove() methods.  A driver may be bound to this device when we
+ * return from this function, or any later moment (e.g. maybe hotplugging will
+ * load the driver module).  This call is not appropriate for use by mainboard
+ * initialization logic, which usually runs during an arch_initcall() long
+ * before any i2c_adapter could exist.
+ *
+ * This returns the new i2c client, which may be saved for later use with
+ * i2c_unregister_device(); or NULL to indicate an error.
+ */
+struct i2c_client *
+i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
+{
+	struct i2c_client	*client;
+	int			status;
+
+	client = kzalloc(sizeof *client, GFP_KERNEL);
+	if (!client)
+		return NULL;
+
+	client->adapter = adap;
+
+	client->dev.platform_data = info->platform_data;
+
+	if (info->archdata)
+		client->dev.archdata = *info->archdata;
+
+	client->flags = info->flags;
+	client->addr = info->addr;
+	client->irq = info->irq;
+
+	strlcpy(client->name, info->type, sizeof(client->name));
+
+	/* Check for address validity */
+	status = i2c_check_client_addr_validity(client);
+	if (status) {
+		dev_err(&adap->dev, "Invalid %d-bit I2C address 0x%02hx\n",
+			client->flags & I2C_CLIENT_TEN ? 10 : 7, client->addr);
+		goto out_err_silent;
+	}
+
+	/* Check for address business */
+	status = i2c_check_addr_busy(adap, client->addr);
+	if (status)
+		goto out_err;
+
+	client->dev.parent = &client->adapter->dev;
+	client->dev.bus = &i2c_bus_type;
+	client->dev.type = &i2c_client_type;
+	client->dev.of_node = info->of_node;
+	client->dev.fwnode = info->fwnode;
+
+	i2c_dev_set_name(adap, client);
+	status = device_register(&client->dev);
+	if (status)
+		goto out_err;
+
+	dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
+		client->name, dev_name(&client->dev));
+
+	return client;
+
+out_err:
+	dev_err(&adap->dev, "Failed to register i2c client %s at 0x%02x "
+		"(%d)\n", client->name, client->addr, status);
+out_err_silent:
+	kfree(client);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(i2c_new_device);
+
+
+/**
+ * i2c_unregister_device - reverse effect of i2c_new_device()
+ * @client: value returned from i2c_new_device()
+ * Context: can sleep
+ */
+void i2c_unregister_device(struct i2c_client *client)
+{
+	device_unregister(&client->dev);
+}
+EXPORT_SYMBOL_GPL(i2c_unregister_device);
+
+
+static const struct i2c_device_id dummy_id[] = {
+	{ "dummy", 0 },
+	{ },
+};
+
+static int dummy_probe(struct i2c_client *client,
+		       const struct i2c_device_id *id)
+{
+	return 0;
+}
+
+static int dummy_remove(struct i2c_client *client)
+{
+	return 0;
+}
+
+static struct i2c_driver dummy_driver = {
+	.driver.name	= "dummy",
+	.probe		= dummy_probe,
+	.remove		= dummy_remove,
+	.id_table	= dummy_id,
+};
+
+/**
+ * i2c_new_dummy - return a new i2c device bound to a dummy driver
+ * @adapter: the adapter managing the device
+ * @address: seven bit address to be used
+ * Context: can sleep
+ *
+ * This returns an I2C client bound to the "dummy" driver, intended for use
+ * with devices that consume multiple addresses.  Examples of such chips
+ * include various EEPROMS (like 24c04 and 24c08 models).
+ *
+ * These dummy devices have two main uses.  First, most I2C and SMBus calls
+ * except i2c_transfer() need a client handle; the dummy will be that handle.
+ * And second, this prevents the specified address from being bound to a
+ * different driver.
+ *
+ * This returns the new i2c client, which should be saved for later use with
+ * i2c_unregister_device(); or NULL to indicate an error.
+ */
+struct i2c_client *i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
+{
+	struct i2c_board_info info = {
+		I2C_BOARD_INFO("dummy", address),
+	};
+
+	return i2c_new_device(adapter, &info);
+}
+EXPORT_SYMBOL_GPL(i2c_new_dummy);
+
+/* ------------------------------------------------------------------------- */
+
+/* I2C bus adapters -- one roots each I2C or SMBUS segment */
+
+static void i2c_adapter_dev_release(struct device *dev)
+{
+	struct i2c_adapter *adap = to_i2c_adapter(dev);
+	complete(&adap->dev_released);
+}
+
+/*
+ * This function is only needed for mutex_lock_nested, so it is never
+ * called unless locking correctness checking is enabled. Thus we
+ * make it inline to avoid a compiler warning. That's what gcc ends up
+ * doing anyway.
+ */
+static inline unsigned int i2c_adapter_depth(struct i2c_adapter *adapter)
+{
+	unsigned int depth = 0;
+
+	while ((adapter = i2c_parent_is_i2c_adapter(adapter)))
+		depth++;
+
+	return depth;
+}
+
+/*
+ * Let users instantiate I2C devices through sysfs. This can be used when
+ * platform initialization code doesn't contain the proper data for
+ * whatever reason. Also useful for drivers that do device detection and
+ * detection fails, either because the device uses an unexpected address,
+ * or this is a compatible device with different ID register values.
+ *
+ * Parameter checking may look overzealous, but we really don't want
+ * the user to provide incorrect parameters.
+ */
+static ssize_t
+i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr,
+		     const char *buf, size_t count)
+{
+	struct i2c_adapter *adap = to_i2c_adapter(dev);
+	struct i2c_board_info info;
+	struct i2c_client *client;
+	char *blank, end;
+	int res;
+
+	memset(&info, 0, sizeof(struct i2c_board_info));
+
+	blank = strchr(buf, ' ');
+	if (!blank) {
+		dev_err(dev, "%s: Missing parameters\n", "new_device");
+		return -EINVAL;
+	}
+	if (blank - buf > I2C_NAME_SIZE - 1) {
+		dev_err(dev, "%s: Invalid device name\n", "new_device");
+		return -EINVAL;
+	}
+	memcpy(info.type, buf, blank - buf);
+
+	/* Parse remaining parameters, reject extra parameters */
+	res = sscanf(++blank, "%hi%c", &info.addr, &end);
+	if (res < 1) {
+		dev_err(dev, "%s: Can't parse I2C address\n", "new_device");
+		return -EINVAL;
+	}
+	if (res > 1  && end != '\n') {
+		dev_err(dev, "%s: Extra parameters\n", "new_device");
+		return -EINVAL;
+	}
+
+	client = i2c_new_device(adap, &info);
+	if (!client)
+		return -EINVAL;
+
+	/* Keep track of the added device */
+	mutex_lock(&adap->userspace_clients_lock);
+	list_add_tail(&client->detected, &adap->userspace_clients);
+	mutex_unlock(&adap->userspace_clients_lock);
+	dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
+		 info.type, info.addr);
+
+	return count;
+}
+static DEVICE_ATTR(new_device, S_IWUSR, NULL, i2c_sysfs_new_device);
+
+/*
+ * And of course let the users delete the devices they instantiated, if
+ * they got it wrong. This interface can only be used to delete devices
+ * instantiated by i2c_sysfs_new_device above. This guarantees that we
+ * don't delete devices to which some kernel code still has references.
+ *
+ * Parameter checking may look overzealous, but we really don't want
+ * the user to delete the wrong device.
+ */
+static ssize_t
+i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr,
+			const char *buf, size_t count)
+{
+	struct i2c_adapter *adap = to_i2c_adapter(dev);
+	struct i2c_client *client, *next;
+	unsigned short addr;
+	char end;
+	int res;
+
+	/* Parse parameters, reject extra parameters */
+	res = sscanf(buf, "%hi%c", &addr, &end);
+	if (res < 1) {
+		dev_err(dev, "%s: Can't parse I2C address\n", "delete_device");
+		return -EINVAL;
+	}
+	if (res > 1  && end != '\n') {
+		dev_err(dev, "%s: Extra parameters\n", "delete_device");
+		return -EINVAL;
+	}
+
+	/* Make sure the device was added through sysfs */
+	res = -ENOENT;
+	mutex_lock_nested(&adap->userspace_clients_lock,
+			  i2c_adapter_depth(adap));
+	list_for_each_entry_safe(client, next, &adap->userspace_clients,
+				 detected) {
+		if (client->addr == addr) {
+			dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
+				 "delete_device", client->name, client->addr);
+
+			list_del(&client->detected);
+			i2c_unregister_device(client);
+			res = count;
+			break;
+		}
+	}
+	mutex_unlock(&adap->userspace_clients_lock);
+
+	if (res < 0)
+		dev_err(dev, "%s: Can't find device in list\n",
+			"delete_device");
+	return res;
+}
+static DEVICE_ATTR_IGNORE_LOCKDEP(delete_device, S_IWUSR, NULL,
+				   i2c_sysfs_delete_device);
+
+static struct attribute *i2c_adapter_attrs[] = {
+	&dev_attr_name.attr,
+	&dev_attr_new_device.attr,
+	&dev_attr_delete_device.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(i2c_adapter);
+
+struct device_type i2c_adapter_type = {
+	.groups		= i2c_adapter_groups,
+	.release	= i2c_adapter_dev_release,
+};
+EXPORT_SYMBOL_GPL(i2c_adapter_type);
+
+/**
+ * i2c_verify_adapter - return parameter as i2c_adapter or NULL
+ * @dev: device, probably from some driver model iterator
+ *
+ * When traversing the driver model tree, perhaps using driver model
+ * iterators like @device_for_each_child(), you can't assume very much
+ * about the nodes you find.  Use this function to avoid oopses caused
+ * by wrongly treating some non-I2C device as an i2c_adapter.
+ */
+struct i2c_adapter *i2c_verify_adapter(struct device *dev)
+{
+	return (dev->type == &i2c_adapter_type)
+			? to_i2c_adapter(dev)
+			: NULL;
+}
+EXPORT_SYMBOL(i2c_verify_adapter);
+
+#ifdef CONFIG_I2C_COMPAT
+static struct class_compat *i2c_adapter_compat_class;
+#endif
+
+static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
+{
+	struct i2c_devinfo	*devinfo;
+
+	down_read(&__i2c_board_lock);
+	list_for_each_entry(devinfo, &__i2c_board_list, list) {
+		if (devinfo->busnum == adapter->nr
+				&& !i2c_new_device(adapter,
+						&devinfo->board_info))
+			dev_err(&adapter->dev,
+				"Can't create device at 0x%02x\n",
+				devinfo->board_info.addr);
+	}
+	up_read(&__i2c_board_lock);
+}
+
+/* OF support code */
+
+#if IS_ENABLED(CONFIG_OF)
+static struct i2c_client *of_i2c_register_device(struct i2c_adapter *adap,
+						 struct device_node *node)
+{
+	struct i2c_client *result;
+	struct i2c_board_info info = {};
+	struct dev_archdata dev_ad = {};
+	const __be32 *addr;
+	int len;
+
+	dev_dbg(&adap->dev, "of_i2c: register %s\n", node->full_name);
+
+	if (of_modalias_node(node, info.type, sizeof(info.type)) < 0) {
+		dev_err(&adap->dev, "of_i2c: modalias failure on %s\n",
+			node->full_name);
+		return ERR_PTR(-EINVAL);
+	}
+
+	addr = of_get_property(node, "reg", &len);
+	if (!addr || (len < sizeof(int))) {
+		dev_err(&adap->dev, "of_i2c: invalid reg on %s\n",
+			node->full_name);
+		return ERR_PTR(-EINVAL);
+	}
+
+	info.addr = be32_to_cpup(addr);
+	if (info.addr > (1 << 10) - 1) {
+		dev_err(&adap->dev, "of_i2c: invalid addr=%x on %s\n",
+			info.addr, node->full_name);
+		return ERR_PTR(-EINVAL);
+	}
+
+	info.of_node = of_node_get(node);
+	info.archdata = &dev_ad;
+
+	if (of_get_property(node, "wakeup-source", NULL))
+		info.flags |= I2C_CLIENT_WAKE;
+
+	result = i2c_new_device(adap, &info);
+	if (result == NULL) {
+		dev_err(&adap->dev, "of_i2c: Failure registering %s\n",
+			node->full_name);
+		of_node_put(node);
+		return ERR_PTR(-EINVAL);
+	}
+	return result;
+}
+
+static void of_i2c_register_devices(struct i2c_adapter *adap)
+{
+	struct device_node *node;
+
+	/* Only register child devices if the adapter has a node pointer set */
+	if (!adap->dev.of_node)
+		return;
+
+	dev_dbg(&adap->dev, "of_i2c: walking child nodes\n");
+
+	for_each_available_child_of_node(adap->dev.of_node, node)
+		of_i2c_register_device(adap, node);
+}
+
+static int of_dev_node_match(struct device *dev, void *data)
+{
+	return dev->of_node == data;
+}
+
+/* must call put_device() when done with returned i2c_client device */
+struct i2c_client *of_find_i2c_device_by_node(struct device_node *node)
+{
+	struct device *dev;
+
+	dev = bus_find_device(&i2c_bus_type, NULL, node,
+					 of_dev_node_match);
+	if (!dev)
+		return NULL;
+
+	return i2c_verify_client(dev);
+}
+EXPORT_SYMBOL(of_find_i2c_device_by_node);
+
+/* must call put_device() when done with returned i2c_adapter device */
+struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
+{
+	struct device *dev;
+
+	dev = bus_find_device(&i2c_bus_type, NULL, node,
+					 of_dev_node_match);
+	if (!dev)
+		return NULL;
+
+	return i2c_verify_adapter(dev);
+}
+EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
+#else
+static void of_i2c_register_devices(struct i2c_adapter *adap) { }
+#endif /* CONFIG_OF */
+
+static int i2c_do_add_adapter(struct i2c_driver *driver,
+			      struct i2c_adapter *adap)
+{
+	/* Detect supported devices on that bus, and instantiate them */
+	i2c_detect(adap, driver);
+
+	/* Let legacy drivers scan this bus for matching devices */
+	if (driver->attach_adapter) {
+		dev_warn(&adap->dev, "%s: attach_adapter method is deprecated\n",
+			 driver->driver.name);
+		dev_warn(&adap->dev, "Please use another way to instantiate "
+			 "your i2c_client\n");
+		/* We ignore the return code; if it fails, too bad */
+		driver->attach_adapter(adap);
+	}
+	return 0;
+}
+
+static int __process_new_adapter(struct device_driver *d, void *data)
+{
+	return i2c_do_add_adapter(to_i2c_driver(d), data);
+}
+
+static int i2c_register_adapter(struct i2c_adapter *adap)
+{
+	int res = 0;
+
+	/* Can't register until after driver model init */
+	if (unlikely(WARN_ON(!i2c_bus_type.p))) {
+		res = -EAGAIN;
+		goto out_list;
+	}
+
+	/* Sanity checks */
+	if (unlikely(adap->name[0] == '\0')) {
+		pr_err("i2c-core: Attempt to register an adapter with "
+		       "no name!\n");
+		return -EINVAL;
+	}
+	if (unlikely(!adap->algo)) {
+		pr_err("i2c-core: Attempt to register adapter '%s' with "
+		       "no algo!\n", adap->name);
+		return -EINVAL;
+	}
+
+	rt_mutex_init(&adap->bus_lock);
+	mutex_init(&adap->userspace_clients_lock);
+	INIT_LIST_HEAD(&adap->userspace_clients);
+
+	/* Set default timeout to 1 second if not already set */
+	if (adap->timeout == 0)
+		adap->timeout = HZ;
+
+	dev_set_name(&adap->dev, "i2c-%d", adap->nr);
+	adap->dev.bus = &i2c_bus_type;
+	adap->dev.type = &i2c_adapter_type;
+	res = device_register(&adap->dev);
+	if (res)
+		goto out_list;
+
+	dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
+
+	pm_runtime_no_callbacks(&adap->dev);
+
+#ifdef CONFIG_I2C_COMPAT
+	res = class_compat_create_link(i2c_adapter_compat_class, &adap->dev,
+				       adap->dev.parent);
+	if (res)
+		dev_warn(&adap->dev,
+			 "Failed to create compatibility class link\n");
+#endif
+
+	/* bus recovery specific initialization */
+	if (adap->bus_recovery_info) {
+		struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
+
+		if (!bri->recover_bus) {
+			dev_err(&adap->dev, "No recover_bus() found, not using recovery\n");
+			adap->bus_recovery_info = NULL;
+			goto exit_recovery;
+		}
+
+		/* Generic GPIO recovery */
+		if (bri->recover_bus == i2c_generic_gpio_recovery) {
+			if (!gpio_is_valid(bri->scl_gpio)) {
+				dev_err(&adap->dev, "Invalid SCL gpio, not using recovery\n");
+				adap->bus_recovery_info = NULL;
+				goto exit_recovery;
+			}
+
+			if (gpio_is_valid(bri->sda_gpio))
+				bri->get_sda = get_sda_gpio_value;
+			else
+				bri->get_sda = NULL;
+
+			bri->get_scl = get_scl_gpio_value;
+			bri->set_scl = set_scl_gpio_value;
+		} else if (!bri->set_scl || !bri->get_scl) {
+			/* Generic SCL recovery */
+			dev_err(&adap->dev, "No {get|set}_gpio() found, not using recovery\n");
+			adap->bus_recovery_info = NULL;
+		}
+	}
+
+exit_recovery:
+	/* create pre-declared device nodes */
+	of_i2c_register_devices(adap);
+	acpi_i2c_register_devices(adap);
+	acpi_i2c_install_space_handler(adap);
+
+	if (adap->nr < __i2c_first_dynamic_bus_num)
+		i2c_scan_static_board_info(adap);
+
+	/* Notify drivers */
+	mutex_lock(&core_lock);
+	bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter);
+	mutex_unlock(&core_lock);
+
+	return 0;
+
+out_list:
+	mutex_lock(&core_lock);
+	idr_remove(&i2c_adapter_idr, adap->nr);
+	mutex_unlock(&core_lock);
+	return res;
+}
+
+/**
+ * __i2c_add_numbered_adapter - i2c_add_numbered_adapter where nr is never -1
+ * @adap: the adapter to register (with adap->nr initialized)
+ * Context: can sleep
+ *
+ * See i2c_add_numbered_adapter() for details.
+ */
+static int __i2c_add_numbered_adapter(struct i2c_adapter *adap)
+{
+	int	id;
+
+	mutex_lock(&core_lock);
+	id = idr_alloc(&i2c_adapter_idr, adap, adap->nr, adap->nr + 1,
+		       GFP_KERNEL);
+	mutex_unlock(&core_lock);
+	if (id < 0)
+		return id == -ENOSPC ? -EBUSY : id;
+
+	return i2c_register_adapter(adap);
+}
+
+/**
+ * i2c_add_adapter - declare i2c adapter, use dynamic bus number
+ * @adapter: the adapter to add
+ * Context: can sleep
+ *
+ * This routine is used to declare an I2C adapter when its bus number
+ * doesn't matter or when its bus number is specified by an dt alias.
+ * Examples of bases when the bus number doesn't matter: I2C adapters
+ * dynamically added by USB links or PCI plugin cards.
+ *
+ * When this returns zero, a new bus number was allocated and stored
+ * in adap->nr, and the specified adapter became available for clients.
+ * Otherwise, a negative errno value is returned.
+ */
+int i2c_add_adapter(struct i2c_adapter *adapter)
+{
+	struct device *dev = &adapter->dev;
+	int id;
+
+	if (dev->of_node) {
+		id = of_alias_get_id(dev->of_node, "i2c");
+		if (id >= 0) {
+			adapter->nr = id;
+			return __i2c_add_numbered_adapter(adapter);
+		}
+	}
+
+	mutex_lock(&core_lock);
+	id = idr_alloc(&i2c_adapter_idr, adapter,
+		       __i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
+	mutex_unlock(&core_lock);
+	if (id < 0)
+		return id;
+
+	adapter->nr = id;
+
+	return i2c_register_adapter(adapter);
+}
+EXPORT_SYMBOL(i2c_add_adapter);
+
+/**
+ * i2c_add_numbered_adapter - declare i2c adapter, use static bus number
+ * @adap: the adapter to register (with adap->nr initialized)
+ * Context: can sleep
+ *
+ * This routine is used to declare an I2C adapter when its bus number
+ * matters.  For example, use it for I2C adapters from system-on-chip CPUs,
+ * or otherwise built in to the system's mainboard, and where i2c_board_info
+ * is used to properly configure I2C devices.
+ *
+ * If the requested bus number is set to -1, then this function will behave
+ * identically to i2c_add_adapter, and will dynamically assign a bus number.
+ *
+ * If no devices have pre-been declared for this bus, then be sure to
+ * register the adapter before any dynamically allocated ones.  Otherwise
+ * the required bus ID may not be available.
+ *
+ * When this returns zero, the specified adapter became available for
+ * clients using the bus number provided in adap->nr.  Also, the table
+ * of I2C devices pre-declared using i2c_register_board_info() is scanned,
+ * and the appropriate driver model device nodes are created.  Otherwise, a
+ * negative errno value is returned.
+ */
+int i2c_add_numbered_adapter(struct i2c_adapter *adap)
+{
+	if (adap->nr == -1) /* -1 means dynamically assign bus id */
+		return i2c_add_adapter(adap);
+
+	return __i2c_add_numbered_adapter(adap);
+}
+EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
+
+static void i2c_do_del_adapter(struct i2c_driver *driver,
+			      struct i2c_adapter *adapter)
+{
+	struct i2c_client *client, *_n;
+
+	/* Remove the devices we created ourselves as the result of hardware
+	 * probing (using a driver's detect method) */
+	list_for_each_entry_safe(client, _n, &driver->clients, detected) {
+		if (client->adapter == adapter) {
+			dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
+				client->name, client->addr);
+			list_del(&client->detected);
+			i2c_unregister_device(client);
+		}
+	}
+}
+
+static int __unregister_client(struct device *dev, void *dummy)
+{
+	struct i2c_client *client = i2c_verify_client(dev);
+	if (client && strcmp(client->name, "dummy"))
+		i2c_unregister_device(client);
+	return 0;
+}
+
+static int __unregister_dummy(struct device *dev, void *dummy)
+{
+	struct i2c_client *client = i2c_verify_client(dev);
+	if (client)
+		i2c_unregister_device(client);
+	return 0;
+}
+
+static int __process_removed_adapter(struct device_driver *d, void *data)
+{
+	i2c_do_del_adapter(to_i2c_driver(d), data);
+	return 0;
+}
+
+/**
+ * i2c_del_adapter - unregister I2C adapter
+ * @adap: the adapter being unregistered
+ * Context: can sleep
+ *
+ * This unregisters an I2C adapter which was previously registered
+ * by @i2c_add_adapter or @i2c_add_numbered_adapter.
+ */
+void i2c_del_adapter(struct i2c_adapter *adap)
+{
+	struct i2c_adapter *found;
+	struct i2c_client *client, *next;
+
+	/* First make sure that this adapter was ever added */
+	mutex_lock(&core_lock);
+	found = idr_find(&i2c_adapter_idr, adap->nr);
+	mutex_unlock(&core_lock);
+	if (found != adap) {
+		pr_debug("i2c-core: attempting to delete unregistered "
+			 "adapter [%s]\n", adap->name);
+		return;
+	}
+
+	acpi_i2c_remove_space_handler(adap);
+	/* Tell drivers about this removal */
+	mutex_lock(&core_lock);
+	bus_for_each_drv(&i2c_bus_type, NULL, adap,
+			       __process_removed_adapter);
+	mutex_unlock(&core_lock);
+
+	/* Remove devices instantiated from sysfs */
+	mutex_lock_nested(&adap->userspace_clients_lock,
+			  i2c_adapter_depth(adap));
+	list_for_each_entry_safe(client, next, &adap->userspace_clients,
+				 detected) {
+		dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
+			client->addr);
+		list_del(&client->detected);
+		i2c_unregister_device(client);
+	}
+	mutex_unlock(&adap->userspace_clients_lock);
+
+	/* Detach any active clients. This can't fail, thus we do not
+	 * check the returned value. This is a two-pass process, because
+	 * we can't remove the dummy devices during the first pass: they
+	 * could have been instantiated by real devices wishing to clean
+	 * them up properly, so we give them a chance to do that first. */
+	device_for_each_child(&adap->dev, NULL, __unregister_client);
+	device_for_each_child(&adap->dev, NULL, __unregister_dummy);
+
+#ifdef CONFIG_I2C_COMPAT
+	class_compat_remove_link(i2c_adapter_compat_class, &adap->dev,
+				 adap->dev.parent);
+#endif
+
+	/* device name is gone after device_unregister */
+	dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
+
+	/* wait until all references to the device are gone
+	 *
+	 * FIXME: This is old code and should ideally be replaced by an
+	 * alternative which results in decoupling the lifetime of the struct
+	 * device from the i2c_adapter, like spi or netdev do. Any solution
+	 * should be throughly tested with DEBUG_KOBJECT_RELEASE enabled!
+	 */
+	init_completion(&adap->dev_released);
+	device_unregister(&adap->dev);
+	wait_for_completion(&adap->dev_released);
+
+	/* free bus id */
+	mutex_lock(&core_lock);
+	idr_remove(&i2c_adapter_idr, adap->nr);
+	mutex_unlock(&core_lock);
+
+	/* Clear the device structure in case this adapter is ever going to be
+	   added again */
+	memset(&adap->dev, 0, sizeof(adap->dev));
+}
+EXPORT_SYMBOL(i2c_del_adapter);
+
+/* ------------------------------------------------------------------------- */
+
+int i2c_for_each_dev(void *data, int (*fn)(struct device *, void *))
+{
+	int res;
+
+	mutex_lock(&core_lock);
+	res = bus_for_each_dev(&i2c_bus_type, NULL, data, fn);
+	mutex_unlock(&core_lock);
+
+	return res;
+}
+EXPORT_SYMBOL_GPL(i2c_for_each_dev);
+
+static int __process_new_driver(struct device *dev, void *data)
+{
+	if (dev->type != &i2c_adapter_type)
+		return 0;
+	return i2c_do_add_adapter(data, to_i2c_adapter(dev));
+}
+
+/*
+ * An i2c_driver is used with one or more i2c_client (device) nodes to access
+ * i2c slave chips, on a bus instance associated with some i2c_adapter.
+ */
+
+int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
+{
+	int res;
+
+	/* Can't register until after driver model init */
+	if (unlikely(WARN_ON(!i2c_bus_type.p)))
+		return -EAGAIN;
+
+	/* add the driver to the list of i2c drivers in the driver core */
+	driver->driver.owner = owner;
+	driver->driver.bus = &i2c_bus_type;
+
+	/* When registration returns, the driver core
+	 * will have called probe() for all matching-but-unbound devices.
+	 */
+	res = driver_register(&driver->driver);
+	if (res)
+		return res;
+
+	pr_debug("i2c-core: driver [%s] registered\n", driver->driver.name);
+
+	INIT_LIST_HEAD(&driver->clients);
+	/* Walk the adapters that are already present */
+	i2c_for_each_dev(driver, __process_new_driver);
+
+	return 0;
+}
+EXPORT_SYMBOL(i2c_register_driver);
+
+static int __process_removed_driver(struct device *dev, void *data)
+{
+	if (dev->type == &i2c_adapter_type)
+		i2c_do_del_adapter(data, to_i2c_adapter(dev));
+	return 0;
+}
+
+/**
+ * i2c_del_driver - unregister I2C driver
+ * @driver: the driver being unregistered
+ * Context: can sleep
+ */
+void i2c_del_driver(struct i2c_driver *driver)
+{
+	i2c_for_each_dev(driver, __process_removed_driver);
+
+	driver_unregister(&driver->driver);
+	pr_debug("i2c-core: driver [%s] unregistered\n", driver->driver.name);
+}
+EXPORT_SYMBOL(i2c_del_driver);
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * i2c_use_client - increments the reference count of the i2c client structure
+ * @client: the client being referenced
+ *
+ * Each live reference to a client should be refcounted. The driver model does
+ * that automatically as part of driver binding, so that most drivers don't
+ * need to do this explicitly: they hold a reference until they're unbound
+ * from the device.
+ *
+ * A pointer to the client with the incremented reference counter is returned.
+ */
+struct i2c_client *i2c_use_client(struct i2c_client *client)
+{
+	if (client && get_device(&client->dev))
+		return client;
+	return NULL;
+}
+EXPORT_SYMBOL(i2c_use_client);
+
+/**
+ * i2c_release_client - release a use of the i2c client structure
+ * @client: the client being no longer referenced
+ *
+ * Must be called when a user of a client is finished with it.
+ */
+void i2c_release_client(struct i2c_client *client)
+{
+	if (client)
+		put_device(&client->dev);
+}
+EXPORT_SYMBOL(i2c_release_client);
+
+struct i2c_cmd_arg {
+	unsigned	cmd;
+	void		*arg;
+};
+
+static int i2c_cmd(struct device *dev, void *_arg)
+{
+	struct i2c_client	*client = i2c_verify_client(dev);
+	struct i2c_cmd_arg	*arg = _arg;
+	struct i2c_driver	*driver;
+
+	if (!client || !client->dev.driver)
+		return 0;
+
+	driver = to_i2c_driver(client->dev.driver);
+	if (driver->command)
+		driver->command(client, arg->cmd, arg->arg);
+	return 0;
+}
+
+void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
+{
+	struct i2c_cmd_arg	cmd_arg;
+
+	cmd_arg.cmd = cmd;
+	cmd_arg.arg = arg;
+	device_for_each_child(&adap->dev, &cmd_arg, i2c_cmd);
+}
+EXPORT_SYMBOL(i2c_clients_command);
+
+#if IS_ENABLED(CONFIG_OF_DYNAMIC)
+static int of_i2c_notify(struct notifier_block *nb, unsigned long action,
+			 void *arg)
+{
+	struct of_reconfig_data *rd = arg;
+	struct i2c_adapter *adap;
+	struct i2c_client *client;
+
+	switch (of_reconfig_get_state_change(action, rd)) {
+	case OF_RECONFIG_CHANGE_ADD:
+		adap = of_find_i2c_adapter_by_node(rd->dn->parent);
+		if (adap == NULL)
+			return NOTIFY_OK;	/* not for us */
+
+		client = of_i2c_register_device(adap, rd->dn);
+		put_device(&adap->dev);
+
+		if (IS_ERR(client)) {
+			pr_err("%s: failed to create for '%s'\n",
+					__func__, rd->dn->full_name);
+			return notifier_from_errno(PTR_ERR(client));
+		}
+		break;
+	case OF_RECONFIG_CHANGE_REMOVE:
+		/* find our device by node */
+		client = of_find_i2c_device_by_node(rd->dn);
+		if (client == NULL)
+			return NOTIFY_OK;	/* no? not meant for us */
+
+		/* unregister takes one ref away */
+		i2c_unregister_device(client);
+
+		/* and put the reference of the find */
+		put_device(&client->dev);
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+static struct notifier_block i2c_of_notifier = {
+	.notifier_call = of_i2c_notify,
+};
+#else
+extern struct notifier_block i2c_of_notifier;
+#endif /* CONFIG_OF_DYNAMIC */
+
+static int __init i2c_init(void)
+{
+	int retval;
+
+	retval = of_alias_get_highest_id("i2c");
+
+	down_write(&__i2c_board_lock);
+	if (retval >= __i2c_first_dynamic_bus_num)
+		__i2c_first_dynamic_bus_num = retval + 1;
+	up_write(&__i2c_board_lock);
+
+	retval = bus_register(&i2c_bus_type);
+	if (retval)
+		return retval;
+#ifdef CONFIG_I2C_COMPAT
+	i2c_adapter_compat_class = class_compat_register("i2c-adapter");
+	if (!i2c_adapter_compat_class) {
+		retval = -ENOMEM;
+		goto bus_err;
+	}
+#endif
+	retval = i2c_add_driver(&dummy_driver);
+	if (retval)
+		goto class_err;
+
+	if (IS_ENABLED(CONFIG_OF_DYNAMIC))
+		WARN_ON(of_reconfig_notifier_register(&i2c_of_notifier));
+
+	return 0;
+
+class_err:
+#ifdef CONFIG_I2C_COMPAT
+	class_compat_unregister(i2c_adapter_compat_class);
+bus_err:
+#endif
+	bus_unregister(&i2c_bus_type);
+	return retval;
+}
+
+static void __exit i2c_exit(void)
+{
+	if (IS_ENABLED(CONFIG_OF_DYNAMIC))
+		WARN_ON(of_reconfig_notifier_unregister(&i2c_of_notifier));
+	i2c_del_driver(&dummy_driver);
+#ifdef CONFIG_I2C_COMPAT
+	class_compat_unregister(i2c_adapter_compat_class);
+#endif
+	bus_unregister(&i2c_bus_type);
+	tracepoint_synchronize_unregister();
+}
+
+/* We must initialize early, because some subsystems register i2c drivers
+ * in subsys_initcall() code, but are linked (and initialized) before i2c.
+ */
+postcore_initcall(i2c_init);
+module_exit(i2c_exit);
+
+/* ----------------------------------------------------
+ * the functional interface to the i2c busses.
+ * ----------------------------------------------------
+ */
+
+/* Check if val is exceeding the quirk IFF quirk is non 0 */
+#define i2c_quirk_exceeded(val, quirk) ((quirk) && ((val) > (quirk)))
+
+static int i2c_quirk_error(struct i2c_adapter *adap, struct i2c_msg *msg, char *err_msg)
+{
+	dev_err_ratelimited(&adap->dev, "adapter quirk: %s (addr 0x%04x, size %u, %s)\n",
+			    err_msg, msg->addr, msg->len,
+			    msg->flags & I2C_M_RD ? "read" : "write");
+	return -EOPNOTSUPP;
+}
+
+static int i2c_check_for_quirks(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+	const struct i2c_adapter_quirks *q = adap->quirks;
+	int max_num = q->max_num_msgs, i;
+	bool do_len_check = true;
+
+	if (q->flags & I2C_AQ_COMB) {
+		max_num = 2;
+
+		/* special checks for combined messages */
+		if (num == 2) {
+			if (q->flags & I2C_AQ_COMB_WRITE_FIRST && msgs[0].flags & I2C_M_RD)
+				return i2c_quirk_error(adap, &msgs[0], "1st comb msg must be write");
+
+			if (q->flags & I2C_AQ_COMB_READ_SECOND && !(msgs[1].flags & I2C_M_RD))
+				return i2c_quirk_error(adap, &msgs[1], "2nd comb msg must be read");
+
+			if (q->flags & I2C_AQ_COMB_SAME_ADDR && msgs[0].addr != msgs[1].addr)
+				return i2c_quirk_error(adap, &msgs[0], "comb msg only to same addr");
+
+			if (i2c_quirk_exceeded(msgs[0].len, q->max_comb_1st_msg_len))
+				return i2c_quirk_error(adap, &msgs[0], "msg too long");
+
+			if (i2c_quirk_exceeded(msgs[1].len, q->max_comb_2nd_msg_len))
+				return i2c_quirk_error(adap, &msgs[1], "msg too long");
+
+			do_len_check = false;
+		}
+	}
+
+	if (i2c_quirk_exceeded(num, max_num))
+		return i2c_quirk_error(adap, &msgs[0], "too many messages");
+
+	for (i = 0; i < num; i++) {
+		u16 len = msgs[i].len;
+
+		if (msgs[i].flags & I2C_M_RD) {
+			if (do_len_check && i2c_quirk_exceeded(len, q->max_read_len))
+				return i2c_quirk_error(adap, &msgs[i], "msg too long");
+		} else {
+			if (do_len_check && i2c_quirk_exceeded(len, q->max_write_len))
+				return i2c_quirk_error(adap, &msgs[i], "msg too long");
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * __i2c_transfer - unlocked flavor of i2c_transfer
+ * @adap: Handle to I2C bus
+ * @msgs: One or more messages to execute before STOP is issued to
+ *	terminate the operation; each message begins with a START.
+ * @num: Number of messages to be executed.
+ *
+ * Returns negative errno, else the number of messages executed.
+ *
+ * Adapter lock must be held when calling this function. No debug logging
+ * takes place. adap->algo->master_xfer existence isn't checked.
+ */
+int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+	unsigned long orig_jiffies;
+	int ret, try;
+
+	if (adap->quirks && i2c_check_for_quirks(adap, msgs, num))
+		return -EOPNOTSUPP;
+
+	/* i2c_trace_msg gets enabled when tracepoint i2c_transfer gets
+	 * enabled.  This is an efficient way of keeping the for-loop from
+	 * being executed when not needed.
+	 */
+	if (static_key_false(&i2c_trace_msg)) {
+		int i;
+		for (i = 0; i < num; i++)
+			if (msgs[i].flags & I2C_M_RD)
+				trace_i2c_read(adap, &msgs[i], i);
+			else
+				trace_i2c_write(adap, &msgs[i], i);
+	}
+
+	/* Retry automatically on arbitration loss */
+	orig_jiffies = jiffies;
+	for (ret = 0, try = 0; try <= adap->retries; try++) {
+		ret = adap->algo->master_xfer(adap, msgs, num);
+		if (ret != -EAGAIN)
+			break;
+		if (time_after(jiffies, orig_jiffies + adap->timeout))
+			break;
+	}
+
+	if (static_key_false(&i2c_trace_msg)) {
+		int i;
+		for (i = 0; i < ret; i++)
+			if (msgs[i].flags & I2C_M_RD)
+				trace_i2c_reply(adap, &msgs[i], i);
+		trace_i2c_result(adap, i, ret);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(__i2c_transfer);
+
+/**
+ * i2c_transfer - execute a single or combined I2C message
+ * @adap: Handle to I2C bus
+ * @msgs: One or more messages to execute before STOP is issued to
+ *	terminate the operation; each message begins with a START.
+ * @num: Number of messages to be executed.
+ *
+ * Returns negative errno, else the number of messages executed.
+ *
+ * Note that there is no requirement that each message be sent to
+ * the same slave address, although that is the most common model.
+ */
+int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+	int ret;
+
+	/* REVISIT the fault reporting model here is weak:
+	 *
+	 *  - When we get an error after receiving N bytes from a slave,
+	 *    there is no way to report "N".
+	 *
+	 *  - When we get a NAK after transmitting N bytes to a slave,
+	 *    there is no way to report "N" ... or to let the master
+	 *    continue executing the rest of this combined message, if
+	 *    that's the appropriate response.
+	 *
+	 *  - When for example "num" is two and we successfully complete
+	 *    the first message but get an error part way through the
+	 *    second, it's unclear whether that should be reported as
+	 *    one (discarding status on the second message) or errno
+	 *    (discarding status on the first one).
+	 */
+
+	if (adap->algo->master_xfer) {
+#ifdef DEBUG
+		for (ret = 0; ret < num; ret++) {
+			dev_dbg(&adap->dev, "master_xfer[%d] %c, addr=0x%02x, "
+				"len=%d%s\n", ret, (msgs[ret].flags & I2C_M_RD)
+				? 'R' : 'W', msgs[ret].addr, msgs[ret].len,
+				(msgs[ret].flags & I2C_M_RECV_LEN) ? "+" : "");
+		}
+#endif
+
+		if (in_atomic() || irqs_disabled()) {
+			ret = i2c_trylock_adapter(adap);
+			if (!ret)
+				/* I2C activity is ongoing. */
+				return -EAGAIN;
+		} else {
+			i2c_lock_adapter(adap);
+		}
+
+		ret = __i2c_transfer(adap, msgs, num);
+		i2c_unlock_adapter(adap);
+
+		return ret;
+	} else {
+		dev_dbg(&adap->dev, "I2C level transfers not supported\n");
+		return -EOPNOTSUPP;
+	}
+}
+EXPORT_SYMBOL(i2c_transfer);
+
+/**
+ * i2c_master_send - issue a single I2C message in master transmit mode
+ * @client: Handle to slave device
+ * @buf: Data that will be written to the slave
+ * @count: How many bytes to write, must be less than 64k since msg.len is u16
+ *
+ * Returns negative errno, or else the number of bytes written.
+ */
+int i2c_master_send(const struct i2c_client *client, const char *buf, int count)
+{
+	int ret;
+	struct i2c_adapter *adap = client->adapter;
+	struct i2c_msg msg;
+
+	msg.addr = client->addr;
+	msg.flags = client->flags & I2C_M_TEN;
+	msg.len = count;
+	msg.buf = (char *)buf;
+
+	ret = i2c_transfer(adap, &msg, 1);
+
+	/*
+	 * If everything went ok (i.e. 1 msg transmitted), return #bytes
+	 * transmitted, else error code.
+	 */
+	return (ret == 1) ? count : ret;
+}
+EXPORT_SYMBOL(i2c_master_send);
+
+/**
+ * i2c_master_recv - issue a single I2C message in master receive mode
+ * @client: Handle to slave device
+ * @buf: Where to store data read from slave
+ * @count: How many bytes to read, must be less than 64k since msg.len is u16
+ *
+ * Returns negative errno, or else the number of bytes read.
+ */
+int i2c_master_recv(const struct i2c_client *client, char *buf, int count)
+{
+	struct i2c_adapter *adap = client->adapter;
+	struct i2c_msg msg;
+	int ret;
+
+	msg.addr = client->addr;
+	msg.flags = client->flags & I2C_M_TEN;
+	msg.flags |= I2C_M_RD;
+	msg.len = count;
+	msg.buf = buf;
+
+	ret = i2c_transfer(adap, &msg, 1);
+
+	/*
+	 * If everything went ok (i.e. 1 msg received), return #bytes received,
+	 * else error code.
+	 */
+	return (ret == 1) ? count : ret;
+}
+EXPORT_SYMBOL(i2c_master_recv);
+
+/* ----------------------------------------------------
+ * the i2c address scanning function
+ * Will not work for 10-bit addresses!
+ * ----------------------------------------------------
+ */
+
+/*
+ * Legacy default probe function, mostly relevant for SMBus. The default
+ * probe method is a quick write, but it is known to corrupt the 24RF08
+ * EEPROMs due to a state machine bug, and could also irreversibly
+ * write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f,
+ * we use a short byte read instead. Also, some bus drivers don't implement
+ * quick write, so we fallback to a byte read in that case too.
+ * On x86, there is another special case for FSC hardware monitoring chips,
+ * which want regular byte reads (address 0x73.) Fortunately, these are the
+ * only known chips using this I2C address on PC hardware.
+ * Returns 1 if probe succeeded, 0 if not.
+ */
+static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr)
+{
+	int err;
+	union i2c_smbus_data dummy;
+
+#ifdef CONFIG_X86
+	if (addr == 0x73 && (adap->class & I2C_CLASS_HWMON)
+	 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA))
+		err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
+				     I2C_SMBUS_BYTE_DATA, &dummy);
+	else
+#endif
+	if (!((addr & ~0x07) == 0x30 || (addr & ~0x0f) == 0x50)
+	 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK))
+		err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_WRITE, 0,
+				     I2C_SMBUS_QUICK, NULL);
+	else if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE))
+		err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
+				     I2C_SMBUS_BYTE, &dummy);
+	else {
+		dev_warn(&adap->dev, "No suitable probing method supported for address 0x%02X\n",
+			 addr);
+		err = -EOPNOTSUPP;
+	}
+
+	return err >= 0;
+}
+
+static int i2c_detect_address(struct i2c_client *temp_client,
+			      struct i2c_driver *driver)
+{
+	struct i2c_board_info info;
+	struct i2c_adapter *adapter = temp_client->adapter;
+	int addr = temp_client->addr;
+	int err;
+
+	/* Make sure the address is valid */
+	err = i2c_check_addr_validity(addr);
+	if (err) {
+		dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
+			 addr);
+		return err;
+	}
+
+	/* Skip if already in use */
+	if (i2c_check_addr_busy(adapter, addr))
+		return 0;
+
+	/* Make sure there is something at this address */
+	if (!i2c_default_probe(adapter, addr))
+		return 0;
+
+	/* Finally call the custom detection function */
+	memset(&info, 0, sizeof(struct i2c_board_info));
+	info.addr = addr;
+	err = driver->detect(temp_client, &info);
+	if (err) {
+		/* -ENODEV is returned if the detection fails. We catch it
+		   here as this isn't an error. */
+		return err == -ENODEV ? 0 : err;
+	}
+
+	/* Consistency check */
+	if (info.type[0] == '\0') {
+		dev_err(&adapter->dev, "%s detection function provided "
+			"no name for 0x%x\n", driver->driver.name,
+			addr);
+	} else {
+		struct i2c_client *client;
+
+		/* Detection succeeded, instantiate the device */
+		if (adapter->class & I2C_CLASS_DEPRECATED)
+			dev_warn(&adapter->dev,
+				"This adapter will soon drop class based instantiation of devices. "
+				"Please make sure client 0x%02x gets instantiated by other means. "
+				"Check 'Documentation/i2c/instantiating-devices' for details.\n",
+				info.addr);
+
+		dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
+			info.type, info.addr);
+		client = i2c_new_device(adapter, &info);
+		if (client)
+			list_add_tail(&client->detected, &driver->clients);
+		else
+			dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n",
+				info.type, info.addr);
+	}
+	return 0;
+}
+
+static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
+{
+	const unsigned short *address_list;
+	struct i2c_client *temp_client;
+	int i, err = 0;
+	int adap_id = i2c_adapter_id(adapter);
+
+	address_list = driver->address_list;
+	if (!driver->detect || !address_list)
+		return 0;
+
+	/* Warn that the adapter lost class based instantiation */
+	if (adapter->class == I2C_CLASS_DEPRECATED) {
+		dev_dbg(&adapter->dev,
+			"This adapter dropped support for I2C classes and "
+			"won't auto-detect %s devices anymore. If you need it, check "
+			"'Documentation/i2c/instantiating-devices' for alternatives.\n",
+			driver->driver.name);
+		return 0;
+	}
+
+	/* Stop here if the classes do not match */
+	if (!(adapter->class & driver->class))
+		return 0;
+
+	/* Set up a temporary client to help detect callback */
+	temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
+	if (!temp_client)
+		return -ENOMEM;
+	temp_client->adapter = adapter;
+
+	for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) {
+		dev_dbg(&adapter->dev, "found normal entry for adapter %d, "
+			"addr 0x%02x\n", adap_id, address_list[i]);
+		temp_client->addr = address_list[i];
+		err = i2c_detect_address(temp_client, driver);
+		if (unlikely(err))
+			break;
+	}
+
+	kfree(temp_client);
+	return err;
+}
+
+int i2c_probe_func_quick_read(struct i2c_adapter *adap, unsigned short addr)
+{
+	return i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
+			      I2C_SMBUS_QUICK, NULL) >= 0;
+}
+EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read);
+
+struct i2c_client *
+i2c_new_probed_device(struct i2c_adapter *adap,
+		      struct i2c_board_info *info,
+		      unsigned short const *addr_list,
+		      int (*probe)(struct i2c_adapter *, unsigned short addr))
+{
+	int i;
+
+	if (!probe)
+		probe = i2c_default_probe;
+
+	for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) {
+		/* Check address validity */
+		if (i2c_check_addr_validity(addr_list[i]) < 0) {
+			dev_warn(&adap->dev, "Invalid 7-bit address "
+				 "0x%02x\n", addr_list[i]);
+			continue;
+		}
+
+		/* Check address availability */
+		if (i2c_check_addr_busy(adap, addr_list[i])) {
+			dev_dbg(&adap->dev, "Address 0x%02x already in "
+				"use, not probing\n", addr_list[i]);
+			continue;
+		}
+
+		/* Test address responsiveness */
+		if (probe(adap, addr_list[i]))
+			break;
+	}
+
+	if (addr_list[i] == I2C_CLIENT_END) {
+		dev_dbg(&adap->dev, "Probing failed, no device found\n");
+		return NULL;
+	}
+
+	info->addr = addr_list[i];
+	return i2c_new_device(adap, info);
+}
+EXPORT_SYMBOL_GPL(i2c_new_probed_device);
+
+struct i2c_adapter *i2c_get_adapter(int nr)
+{
+	struct i2c_adapter *adapter;
+
+	mutex_lock(&core_lock);
+	adapter = idr_find(&i2c_adapter_idr, nr);
+	if (adapter && !try_module_get(adapter->owner))
+		adapter = NULL;
+
+	mutex_unlock(&core_lock);
+	return adapter;
+}
+EXPORT_SYMBOL(i2c_get_adapter);
+
+void i2c_put_adapter(struct i2c_adapter *adap)
+{
+	if (adap)
+		module_put(adap->owner);
+}
+EXPORT_SYMBOL(i2c_put_adapter);
+
+/* The SMBus parts */
+
+#define POLY    (0x1070U << 3)
+static u8 crc8(u16 data)
+{
+	int i;
+
+	for (i = 0; i < 8; i++) {
+		if (data & 0x8000)
+			data = data ^ POLY;
+		data = data << 1;
+	}
+	return (u8)(data >> 8);
+}
+
+/* Incremental CRC8 over count bytes in the array pointed to by p */
+static u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
+{
+	int i;
+
+	for (i = 0; i < count; i++)
+		crc = crc8((crc ^ p[i]) << 8);
+	return crc;
+}
+
+/* Assume a 7-bit address, which is reasonable for SMBus */
+static u8 i2c_smbus_msg_pec(u8 pec, struct i2c_msg *msg)
+{
+	/* The address will be sent first */
+	u8 addr = (msg->addr << 1) | !!(msg->flags & I2C_M_RD);
+	pec = i2c_smbus_pec(pec, &addr, 1);
+
+	/* The data buffer follows */
+	return i2c_smbus_pec(pec, msg->buf, msg->len);
+}
+
+/* Used for write only transactions */
+static inline void i2c_smbus_add_pec(struct i2c_msg *msg)
+{
+	msg->buf[msg->len] = i2c_smbus_msg_pec(0, msg);
+	msg->len++;
+}
+
+/* Return <0 on CRC error
+   If there was a write before this read (most cases) we need to take the
+   partial CRC from the write part into account.
+   Note that this function does modify the message (we need to decrease the
+   message length to hide the CRC byte from the caller). */
+static int i2c_smbus_check_pec(u8 cpec, struct i2c_msg *msg)
+{
+	u8 rpec = msg->buf[--msg->len];
+	cpec = i2c_smbus_msg_pec(cpec, msg);
+
+	if (rpec != cpec) {
+		pr_debug("i2c-core: Bad PEC 0x%02x vs. 0x%02x\n",
+			rpec, cpec);
+		return -EBADMSG;
+	}
+	return 0;
+}
+
+/**
+ * i2c_smbus_read_byte - SMBus "receive byte" protocol
+ * @client: Handle to slave device
+ *
+ * This executes the SMBus "receive byte" protocol, returning negative errno
+ * else the byte received from the device.
+ */
+s32 i2c_smbus_read_byte(const struct i2c_client *client)
+{
+	union i2c_smbus_data data;
+	int status;
+
+	status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+				I2C_SMBUS_READ, 0,
+				I2C_SMBUS_BYTE, &data);
+	return (status < 0) ? status : data.byte;
+}
+EXPORT_SYMBOL(i2c_smbus_read_byte);
+
+/**
+ * i2c_smbus_write_byte - SMBus "send byte" protocol
+ * @client: Handle to slave device
+ * @value: Byte to be sent
+ *
+ * This executes the SMBus "send byte" protocol, returning negative errno
+ * else zero on success.
+ */
+s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value)
+{
+	return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+	                      I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
+}
+EXPORT_SYMBOL(i2c_smbus_write_byte);
+
+/**
+ * i2c_smbus_read_byte_data - SMBus "read byte" protocol
+ * @client: Handle to slave device
+ * @command: Byte interpreted by slave
+ *
+ * This executes the SMBus "read byte" protocol, returning negative errno
+ * else a data byte received from the device.
+ */
+s32 i2c_smbus_read_byte_data(const struct i2c_client *client, u8 command)
+{
+	union i2c_smbus_data data;
+	int status;
+
+	status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+				I2C_SMBUS_READ, command,
+				I2C_SMBUS_BYTE_DATA, &data);
+	return (status < 0) ? status : data.byte;
+}
+EXPORT_SYMBOL(i2c_smbus_read_byte_data);
+
+/**
+ * i2c_smbus_write_byte_data - SMBus "write byte" protocol
+ * @client: Handle to slave device
+ * @command: Byte interpreted by slave
+ * @value: Byte being written
+ *
+ * This executes the SMBus "write byte" protocol, returning negative errno
+ * else zero on success.
+ */
+s32 i2c_smbus_write_byte_data(const struct i2c_client *client, u8 command,
+			      u8 value)
+{
+	union i2c_smbus_data data;
+	data.byte = value;
+	return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+			      I2C_SMBUS_WRITE, command,
+			      I2C_SMBUS_BYTE_DATA, &data);
+}
+EXPORT_SYMBOL(i2c_smbus_write_byte_data);
+
+/**
+ * i2c_smbus_read_word_data - SMBus "read word" protocol
+ * @client: Handle to slave device
+ * @command: Byte interpreted by slave
+ *
+ * This executes the SMBus "read word" protocol, returning negative errno
+ * else a 16-bit unsigned "word" received from the device.
+ */
+s32 i2c_smbus_read_word_data(const struct i2c_client *client, u8 command)
+{
+	union i2c_smbus_data data;
+	int status;
+
+	status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+				I2C_SMBUS_READ, command,
+				I2C_SMBUS_WORD_DATA, &data);
+	return (status < 0) ? status : data.word;
+}
+EXPORT_SYMBOL(i2c_smbus_read_word_data);
+
+/**
+ * i2c_smbus_write_word_data - SMBus "write word" protocol
+ * @client: Handle to slave device
+ * @command: Byte interpreted by slave
+ * @value: 16-bit "word" being written
+ *
+ * This executes the SMBus "write word" protocol, returning negative errno
+ * else zero on success.
+ */
+s32 i2c_smbus_write_word_data(const struct i2c_client *client, u8 command,
+			      u16 value)
+{
+	union i2c_smbus_data data;
+	data.word = value;
+	return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+			      I2C_SMBUS_WRITE, command,
+			      I2C_SMBUS_WORD_DATA, &data);
+}
+EXPORT_SYMBOL(i2c_smbus_write_word_data);
+
+/**
+ * i2c_smbus_read_block_data - SMBus "block read" protocol
+ * @client: Handle to slave device
+ * @command: Byte interpreted by slave
+ * @values: Byte array into which data will be read; big enough to hold
+ *	the data returned by the slave.  SMBus allows at most 32 bytes.
+ *
+ * This executes the SMBus "block read" protocol, returning negative errno
+ * else the number of data bytes in the slave's response.
+ *
+ * Note that using this function requires that the client's adapter support
+ * the I2C_FUNC_SMBUS_READ_BLOCK_DATA functionality.  Not all adapter drivers
+ * support this; its emulation through I2C messaging relies on a specific
+ * mechanism (I2C_M_RECV_LEN) which may not be implemented.
+ */
+s32 i2c_smbus_read_block_data(const struct i2c_client *client, u8 command,
+			      u8 *values)
+{
+	union i2c_smbus_data data;
+	int status;
+
+	status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+				I2C_SMBUS_READ, command,
+				I2C_SMBUS_BLOCK_DATA, &data);
+	if (status)
+		return status;
+
+	memcpy(values, &data.block[1], data.block[0]);
+	return data.block[0];
+}
+EXPORT_SYMBOL(i2c_smbus_read_block_data);
+
+/**
+ * i2c_smbus_write_block_data - SMBus "block write" protocol
+ * @client: Handle to slave device
+ * @command: Byte interpreted by slave
+ * @length: Size of data block; SMBus allows at most 32 bytes
+ * @values: Byte array which will be written.
+ *
+ * This executes the SMBus "block write" protocol, returning negative errno
+ * else zero on success.
+ */
+s32 i2c_smbus_write_block_data(const struct i2c_client *client, u8 command,
+			       u8 length, const u8 *values)
+{
+	union i2c_smbus_data data;
+
+	if (length > I2C_SMBUS_BLOCK_MAX)
+		length = I2C_SMBUS_BLOCK_MAX;
+	data.block[0] = length;
+	memcpy(&data.block[1], values, length);
+	return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+			      I2C_SMBUS_WRITE, command,
+			      I2C_SMBUS_BLOCK_DATA, &data);
+}
+EXPORT_SYMBOL(i2c_smbus_write_block_data);
+
+/* Returns the number of read bytes */
+s32 i2c_smbus_read_i2c_block_data(const struct i2c_client *client, u8 command,
+				  u8 length, u8 *values)
+{
+	union i2c_smbus_data data;
+	int status;
+
+	if (length > I2C_SMBUS_BLOCK_MAX)
+		length = I2C_SMBUS_BLOCK_MAX;
+	data.block[0] = length;
+	status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+				I2C_SMBUS_READ, command,
+				I2C_SMBUS_I2C_BLOCK_DATA, &data);
+	if (status < 0)
+		return status;
+
+	memcpy(values, &data.block[1], data.block[0]);
+	return data.block[0];
+}
+EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data);
+
+s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client, u8 command,
+				   u8 length, const u8 *values)
+{
+	union i2c_smbus_data data;
+
+	if (length > I2C_SMBUS_BLOCK_MAX)
+		length = I2C_SMBUS_BLOCK_MAX;
+	data.block[0] = length;
+	memcpy(data.block + 1, values, length);
+	return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+			      I2C_SMBUS_WRITE, command,
+			      I2C_SMBUS_I2C_BLOCK_DATA, &data);
+}
+EXPORT_SYMBOL(i2c_smbus_write_i2c_block_data);
+
+/* Simulate a SMBus command using the i2c protocol
+   No checking of parameters is done!  */
+static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
+				   unsigned short flags,
+				   char read_write, u8 command, int size,
+				   union i2c_smbus_data *data)
+{
+	/* So we need to generate a series of msgs. In the case of writing, we
+	  need to use only one message; when reading, we need two. We initialize
+	  most things with sane defaults, to keep the code below somewhat
+	  simpler. */
+	unsigned char msgbuf0[I2C_SMBUS_BLOCK_MAX+3];
+	unsigned char msgbuf1[I2C_SMBUS_BLOCK_MAX+2];
+	int num = read_write == I2C_SMBUS_READ ? 2 : 1;
+	int i;
+	u8 partial_pec = 0;
+	int status;
+	struct i2c_msg msg[2] = {
+		{
+			.addr = addr,
+			.flags = flags,
+			.len = 1,
+			.buf = msgbuf0,
+		}, {
+			.addr = addr,
+			.flags = flags | I2C_M_RD,
+			.len = 0,
+			.buf = msgbuf1,
+		},
+	};
+
+	msgbuf0[0] = command;
+	switch (size) {
+	case I2C_SMBUS_QUICK:
+		msg[0].len = 0;
+		/* Special case: The read/write field is used as data */
+		msg[0].flags = flags | (read_write == I2C_SMBUS_READ ?
+					I2C_M_RD : 0);
+		num = 1;
+		break;
+	case I2C_SMBUS_BYTE:
+		if (read_write == I2C_SMBUS_READ) {
+			/* Special case: only a read! */
+			msg[0].flags = I2C_M_RD | flags;
+			num = 1;
+		}
+		break;
+	case I2C_SMBUS_BYTE_DATA:
+		if (read_write == I2C_SMBUS_READ)
+			msg[1].len = 1;
+		else {
+			msg[0].len = 2;
+			msgbuf0[1] = data->byte;
+		}
+		break;
+	case I2C_SMBUS_WORD_DATA:
+		if (read_write == I2C_SMBUS_READ)
+			msg[1].len = 2;
+		else {
+			msg[0].len = 3;
+			msgbuf0[1] = data->word & 0xff;
+			msgbuf0[2] = data->word >> 8;
+		}
+		break;
+	case I2C_SMBUS_PROC_CALL:
+		num = 2; /* Special case */
+		read_write = I2C_SMBUS_READ;
+		msg[0].len = 3;
+		msg[1].len = 2;
+		msgbuf0[1] = data->word & 0xff;
+		msgbuf0[2] = data->word >> 8;
+		break;
+	case I2C_SMBUS_BLOCK_DATA:
+		if (read_write == I2C_SMBUS_READ) {
+			msg[1].flags |= I2C_M_RECV_LEN;
+			msg[1].len = 1; /* block length will be added by
+					   the underlying bus driver */
+		} else {
+			msg[0].len = data->block[0] + 2;
+			if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
+				dev_err(&adapter->dev,
+					"Invalid block write size %d\n",
+					data->block[0]);
+				return -EINVAL;
+			}
+			for (i = 1; i < msg[0].len; i++)
+				msgbuf0[i] = data->block[i-1];
+		}
+		break;
+	case I2C_SMBUS_BLOCK_PROC_CALL:
+		num = 2; /* Another special case */
+		read_write = I2C_SMBUS_READ;
+		if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
+			dev_err(&adapter->dev,
+				"Invalid block write size %d\n",
+				data->block[0]);
+			return -EINVAL;
+		}
+		msg[0].len = data->block[0] + 2;
+		for (i = 1; i < msg[0].len; i++)
+			msgbuf0[i] = data->block[i-1];
+		msg[1].flags |= I2C_M_RECV_LEN;
+		msg[1].len = 1; /* block length will be added by
+				   the underlying bus driver */
+		break;
+	case I2C_SMBUS_I2C_BLOCK_DATA:
+		if (read_write == I2C_SMBUS_READ) {
+			msg[1].len = data->block[0];
+		} else {
+			msg[0].len = data->block[0] + 1;
+			if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 1) {
+				dev_err(&adapter->dev,
+					"Invalid block write size %d\n",
+					data->block[0]);
+				return -EINVAL;
+			}
+			for (i = 1; i <= data->block[0]; i++)
+				msgbuf0[i] = data->block[i];
+		}
+		break;
+	default:
+		dev_err(&adapter->dev, "Unsupported transaction %d\n", size);
+		return -EOPNOTSUPP;
+	}
+
+	i = ((flags & I2C_CLIENT_PEC) && size != I2C_SMBUS_QUICK
+				      && size != I2C_SMBUS_I2C_BLOCK_DATA);
+	if (i) {
+		/* Compute PEC if first message is a write */
+		if (!(msg[0].flags & I2C_M_RD)) {
+			if (num == 1) /* Write only */
+				i2c_smbus_add_pec(&msg[0]);
+			else /* Write followed by read */
+				partial_pec = i2c_smbus_msg_pec(0, &msg[0]);
+		}
+		/* Ask for PEC if last message is a read */
+		if (msg[num-1].flags & I2C_M_RD)
+			msg[num-1].len++;
+	}
+
+	status = i2c_transfer(adapter, msg, num);
+	if (status < 0)
+		return status;
+
+	/* Check PEC if last message is a read */
+	if (i && (msg[num-1].flags & I2C_M_RD)) {
+		status = i2c_smbus_check_pec(partial_pec, &msg[num-1]);
+		if (status < 0)
+			return status;
+	}
+
+	if (read_write == I2C_SMBUS_READ)
+		switch (size) {
+		case I2C_SMBUS_BYTE:
+			data->byte = msgbuf0[0];
+			break;
+		case I2C_SMBUS_BYTE_DATA:
+			data->byte = msgbuf1[0];
+			break;
+		case I2C_SMBUS_WORD_DATA:
+		case I2C_SMBUS_PROC_CALL:
+			data->word = msgbuf1[0] | (msgbuf1[1] << 8);
+			break;
+		case I2C_SMBUS_I2C_BLOCK_DATA:
+			for (i = 0; i < data->block[0]; i++)
+				data->block[i+1] = msgbuf1[i];
+			break;
+		case I2C_SMBUS_BLOCK_DATA:
+		case I2C_SMBUS_BLOCK_PROC_CALL:
+			for (i = 0; i < msgbuf1[0] + 1; i++)
+				data->block[i] = msgbuf1[i];
+			break;
+		}
+	return 0;
+}
+
+/**
+ * i2c_smbus_xfer - execute SMBus protocol operations
+ * @adapter: Handle to I2C bus
+ * @addr: Address of SMBus slave on that bus
+ * @flags: I2C_CLIENT_* flags (usually zero or I2C_CLIENT_PEC)
+ * @read_write: I2C_SMBUS_READ or I2C_SMBUS_WRITE
+ * @command: Byte interpreted by slave, for protocols which use such bytes
+ * @protocol: SMBus protocol operation to execute, such as I2C_SMBUS_PROC_CALL
+ * @data: Data to be read or written
+ *
+ * This executes an SMBus protocol operation, and returns a negative
+ * errno code else zero on success.
+ */
+s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
+		   char read_write, u8 command, int protocol,
+		   union i2c_smbus_data *data)
+{
+	unsigned long orig_jiffies;
+	int try;
+	s32 res;
+
+	/* If enabled, the following two tracepoints are conditional on
+	 * read_write and protocol.
+	 */
+	trace_smbus_write(adapter, addr, flags, read_write,
+			  command, protocol, data);
+	trace_smbus_read(adapter, addr, flags, read_write,
+			 command, protocol);
+
+	flags &= I2C_M_TEN | I2C_CLIENT_PEC | I2C_CLIENT_SCCB;
+
+	if (adapter->algo->smbus_xfer) {
+		i2c_lock_adapter(adapter);
+
+		/* Retry automatically on arbitration loss */
+		orig_jiffies = jiffies;
+		for (res = 0, try = 0; try <= adapter->retries; try++) {
+			res = adapter->algo->smbus_xfer(adapter, addr, flags,
+							read_write, command,
+							protocol, data);
+			if (res != -EAGAIN)
+				break;
+			if (time_after(jiffies,
+				       orig_jiffies + adapter->timeout))
+				break;
+		}
+		i2c_unlock_adapter(adapter);
+
+		if (res != -EOPNOTSUPP || !adapter->algo->master_xfer)
+			goto trace;
+		/*
+		 * Fall back to i2c_smbus_xfer_emulated if the adapter doesn't
+		 * implement native support for the SMBus operation.
+		 */
+	}
+
+	res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write,
+				      command, protocol, data);
+
+trace:
+	/* If enabled, the reply tracepoint is conditional on read_write. */
+	trace_smbus_reply(adapter, addr, flags, read_write,
+			  command, protocol, data);
+	trace_smbus_result(adapter, addr, flags, read_write,
+			   command, protocol, res);
+
+	return res;
+}
+EXPORT_SYMBOL(i2c_smbus_xfer);
+
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb)
+{
+	int ret;
+
+	if (!client || !slave_cb)
+		return -EINVAL;
+
+	if (!(client->flags & I2C_CLIENT_TEN)) {
+		/* Enforce stricter address checking */
+		ret = i2c_check_addr_validity(client->addr);
+		if (ret)
+			return ret;
+	}
+
+	if (!client->adapter->algo->reg_slave)
+		return -EOPNOTSUPP;
+
+	client->slave_cb = slave_cb;
+
+	i2c_lock_adapter(client->adapter);
+	ret = client->adapter->algo->reg_slave(client);
+	i2c_unlock_adapter(client->adapter);
+
+	if (ret)
+		client->slave_cb = NULL;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(i2c_slave_register);
+
+int i2c_slave_unregister(struct i2c_client *client)
+{
+	int ret;
+
+	if (!client->adapter->algo->unreg_slave)
+		return -EOPNOTSUPP;
+
+	i2c_lock_adapter(client->adapter);
+	ret = client->adapter->algo->unreg_slave(client);
+	i2c_unlock_adapter(client->adapter);
+
+	if (ret == 0)
+		client->slave_cb = NULL;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(i2c_slave_unregister);
+#endif
+
+MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
+MODULE_DESCRIPTION("I2C-Bus main module");
+MODULE_LICENSE("GPL");