drivers/i2c/i2c-core-acpi.c - kernel/common - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Linux I2C core ACPI support code
  *
  * Copyright (C) 2014 Intel Corp, Author: Lan Tianyu <[email protected]>
  */

 #include <linux/acpi.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/slab.h>

 #include "i2c-core.h"

 struct i2c_acpi_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;

 struct i2c_acpi_lookup {
 	struct i2c_board_info *info;
 	acpi_handle adapter_handle;
 	acpi_handle device_handle;
 	acpi_handle search_handle;
 	int n;
 	int index;
 	u32 speed;
 	u32 min_speed;
 };

 /**
  * i2c_acpi_get_i2c_resource - Gets I2cSerialBus resource if type matches
  * @ares:	ACPI resource
  * @i2c:	Pointer to I2cSerialBus resource will be returned here
  *
  * Checks if the given ACPI resource is of type I2cSerialBus.
  * In this case, returns a pointer to it to the caller.
  *
  * Returns true if resource type is of I2cSerialBus, otherwise false.
  */
 bool i2c_acpi_get_i2c_resource(struct acpi_resource *ares,
 			       struct acpi_resource_i2c_serialbus **i2c)
 {
 	struct acpi_resource_i2c_serialbus *sb;

 	if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
 		return false;

 	sb = &ares->data.i2c_serial_bus;
 	if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_I2C)
 		return false;

 	*i2c = sb;
 	return true;
 }
 EXPORT_SYMBOL_GPL(i2c_acpi_get_i2c_resource);

 static int i2c_acpi_fill_info(struct acpi_resource *ares, void *data)
 {
 	struct i2c_acpi_lookup *lookup = data;
 	struct i2c_board_info *info = lookup->info;
 	struct acpi_resource_i2c_serialbus *sb;
 	acpi_status status;

 	if (info->addr || !i2c_acpi_get_i2c_resource(ares, &sb))
 		return 1;

 	if (lookup->index != -1 && lookup->n++ != lookup->index)
 		return 1;

 	status = acpi_get_handle(lookup->device_handle,
 				 sb->resource_source.string_ptr,
 				 &lookup->adapter_handle);
 	if (ACPI_FAILURE(status))
 		return 1;

 	info->addr = sb->slave_address;
 	lookup->speed = sb->connection_speed;
 	if (sb->access_mode == ACPI_I2C_10BIT_MODE)
 		info->flags |= I2C_CLIENT_TEN;

 	return 1;
 }

 static const struct acpi_device_id i2c_acpi_ignored_device_ids[] = {
 	/*
 	 * ACPI video acpi_devices, which are handled by the acpi-video driver
 	 * sometimes contain a SERIAL_TYPE_I2C ACPI resource, ignore these.
 	 */
 	{ ACPI_VIDEO_HID, 0 },
 	{}
 };

 static int i2c_acpi_do_lookup(struct acpi_device *adev,
 			      struct i2c_acpi_lookup *lookup)
 {
 	struct i2c_board_info *info = lookup->info;
 	struct list_head resource_list;
 	int ret;

 	if (acpi_bus_get_status(adev) || !adev->status.present)
 		return -EINVAL;

 	if (acpi_match_device_ids(adev, i2c_acpi_ignored_device_ids) == 0)
 		return -ENODEV;

 	memset(info, 0, sizeof(*info));
 	lookup->device_handle = acpi_device_handle(adev);

 	/* Look up for I2cSerialBus resource */
 	INIT_LIST_HEAD(&resource_list);
 	ret = acpi_dev_get_resources(adev, &resource_list,
 				     i2c_acpi_fill_info, lookup);
 	acpi_dev_free_resource_list(&resource_list);

 	if (ret < 0 || !info->addr)
 		return -EINVAL;

 	return 0;
 }

 static int i2c_acpi_get_info(struct acpi_device *adev,
 			     struct i2c_board_info *info,
 			     struct i2c_adapter *adapter,
 			     acpi_handle *adapter_handle)
 {
 	struct list_head resource_list;
 	struct resource_entry *entry;
 	struct i2c_acpi_lookup lookup;
 	int ret;

 	memset(&lookup, 0, sizeof(lookup));
 	lookup.info = info;
 	lookup.index = -1;

 	if (acpi_device_enumerated(adev))
 		return -EINVAL;

 	ret = i2c_acpi_do_lookup(adev, &lookup);
 	if (ret)
 		return ret;

 	if (adapter) {
 		/* The adapter must match the one in I2cSerialBus() connector */
 		if (ACPI_HANDLE(&adapter->dev) != lookup.adapter_handle)
 			return -ENODEV;
 	} else {
 		struct acpi_device *adapter_adev;

 		/* The adapter must be present */
 		if (acpi_bus_get_device(lookup.adapter_handle, &adapter_adev))
 			return -ENODEV;
 		if (acpi_bus_get_status(adapter_adev) ||
 		    !adapter_adev->status.present)
 			return -ENODEV;
 	}

 	info->fwnode = acpi_fwnode_handle(adev);
 	if (adapter_handle)
 		*adapter_handle = lookup.adapter_handle;

 	/* Then fill IRQ number if any */
 	INIT_LIST_HEAD(&resource_list);
 	ret = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
 	if (ret < 0)
 		return -EINVAL;

 	resource_list_for_each_entry(entry, &resource_list) {
 		if (resource_type(entry->res) == IORESOURCE_IRQ) {
 			info->irq = entry->res->start;
 			break;
 		}
 	}

 	acpi_dev_free_resource_list(&resource_list);

 	acpi_set_modalias(adev, dev_name(&adev->dev), info->type,
 			  sizeof(info->type));

 	return 0;
 }

 static void i2c_acpi_register_device(struct i2c_adapter *adapter,
 				     struct acpi_device *adev,
 				     struct i2c_board_info *info)
 {
 	adev->power.flags.ignore_parent = true;
 	acpi_device_set_enumerated(adev);

 	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));
 	}
 }

 static acpi_status i2c_acpi_add_device(acpi_handle handle, u32 level,
 				       void *data, void **return_value)
 {
 	struct i2c_adapter *adapter = data;
 	struct acpi_device *adev;
 	struct i2c_board_info info;

 	if (acpi_bus_get_device(handle, &adev))
 		return AE_OK;

 	if (i2c_acpi_get_info(adev, &info, adapter, NULL))
 		return AE_OK;

 	i2c_acpi_register_device(adapter, adev, &info);

 	return AE_OK;
 }

 #define I2C_ACPI_MAX_SCAN_DEPTH 32

 /**
  * i2c_acpi_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.
  */
 void i2c_acpi_register_devices(struct i2c_adapter *adap)
 {
 	acpi_status status;

 	if (!has_acpi_companion(&adap->dev))
 		return;

 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 				     I2C_ACPI_MAX_SCAN_DEPTH,
 				     i2c_acpi_add_device, NULL,
 				     adap, NULL);
 	if (ACPI_FAILURE(status))
 		dev_warn(&adap->dev, "failed to enumerate I2C slaves\n");
 }

 const struct acpi_device_id *
 i2c_acpi_match_device(const struct acpi_device_id *matches,
 		      struct i2c_client *client)
 {
 	if (!(client && matches))
 		return NULL;

 	return acpi_match_device(matches, &client->dev);
 }

 static acpi_status i2c_acpi_lookup_speed(acpi_handle handle, u32 level,
 					   void *data, void **return_value)
 {
 	struct i2c_acpi_lookup *lookup = data;
 	struct acpi_device *adev;

 	if (acpi_bus_get_device(handle, &adev))
 		return AE_OK;

 	if (i2c_acpi_do_lookup(adev, lookup))
 		return AE_OK;

 	if (lookup->search_handle != lookup->adapter_handle)
 		return AE_OK;

 	if (lookup->speed <= lookup->min_speed)
 		lookup->min_speed = lookup->speed;

 	return AE_OK;
 }

 /**
  * i2c_acpi_find_bus_speed - find I2C bus speed from ACPI
  * @dev: The device owning the bus
  *
  * Find the I2C bus speed by walking the ACPI namespace for all I2C slaves
  * devices connected to this bus and use the speed of slowest device.
  *
  * Returns the speed in Hz or zero
  */
 u32 i2c_acpi_find_bus_speed(struct device *dev)
 {
 	struct i2c_acpi_lookup lookup;
 	struct i2c_board_info dummy;
 	acpi_status status;

 	if (!has_acpi_companion(dev))
 		return 0;

 	memset(&lookup, 0, sizeof(lookup));
 	lookup.search_handle = ACPI_HANDLE(dev);
 	lookup.min_speed = UINT_MAX;
 	lookup.info = &dummy;
 	lookup.index = -1;

 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 				     I2C_ACPI_MAX_SCAN_DEPTH,
 				     i2c_acpi_lookup_speed, NULL,
 				     &lookup, NULL);

 	if (ACPI_FAILURE(status)) {
 		dev_warn(dev, "unable to find I2C bus speed from ACPI\n");
 		return 0;
 	}

 	return lookup.min_speed != UINT_MAX ? lookup.min_speed : 0;
 }
 EXPORT_SYMBOL_GPL(i2c_acpi_find_bus_speed);

 static int i2c_acpi_find_match_adapter(struct device *dev, void *data)
 {
 	struct i2c_adapter *adapter = i2c_verify_adapter(dev);

 	if (!adapter)
 		return 0;

 	return ACPI_HANDLE(dev) == (acpi_handle)data;
 }

 static int i2c_acpi_find_match_device(struct device *dev, void *data)
 {
 	return ACPI_COMPANION(dev) == data;
 }

 struct i2c_adapter *i2c_acpi_find_adapter_by_handle(acpi_handle handle)
 {
 	struct device *dev;

 	dev = bus_find_device(&i2c_bus_type, NULL, handle,
 			      i2c_acpi_find_match_adapter);
 	return dev ? i2c_verify_adapter(dev) : NULL;
 }
 EXPORT_SYMBOL_GPL(i2c_acpi_find_adapter_by_handle);

 static struct i2c_client *i2c_acpi_find_client_by_adev(struct acpi_device *adev)
 {
 	struct device *dev;

 	dev = bus_find_device(&i2c_bus_type, NULL, adev,
 			      i2c_acpi_find_match_device);
 	return dev ? i2c_verify_client(dev) : NULL;
 }

 static int i2c_acpi_notify(struct notifier_block *nb, unsigned long value,
 			   void *arg)
 {
 	struct acpi_device *adev = arg;
 	struct i2c_board_info info;
 	acpi_handle adapter_handle;
 	struct i2c_adapter *adapter;
 	struct i2c_client *client;

 	switch (value) {
 	case ACPI_RECONFIG_DEVICE_ADD:
 		if (i2c_acpi_get_info(adev, &info, NULL, &adapter_handle))
 			break;

 		adapter = i2c_acpi_find_adapter_by_handle(adapter_handle);
 		if (!adapter)
 			break;

 		i2c_acpi_register_device(adapter, adev, &info);
 		break;
 	case ACPI_RECONFIG_DEVICE_REMOVE:
 		if (!acpi_device_enumerated(adev))
 			break;

 		client = i2c_acpi_find_client_by_adev(adev);
 		if (!client)
 			break;

 		i2c_unregister_device(client);
 		put_device(&client->dev);
 		break;
 	}

 	return NOTIFY_OK;
 }

 struct notifier_block i2c_acpi_notifier = {
 	.notifier_call = i2c_acpi_notify,
 };

 /**
  * i2c_acpi_new_device - Create i2c-client for the Nth I2cSerialBus resource
  * @dev:     Device owning the ACPI resources to get the client from
  * @index:   Index of ACPI resource to get
  * @info:    describes the I2C device; note this is modified (addr gets set)
  * Context: can sleep
  *
  * By default the i2c subsys creates an i2c-client for the first I2cSerialBus
  * resource of an acpi_device, but some acpi_devices have multiple I2cSerialBus
  * resources, in that case this function can be used to create an i2c-client
  * for other I2cSerialBus resources in the Current Resource Settings table.
  *
  * Also see i2c_new_device, which this function calls to create the i2c-client.
  *
  * Returns a pointer to the new i2c-client, or error pointer in case of failure.
  * Specifically, -EPROBE_DEFER is returned if the adapter is not found.
  */
 struct i2c_client *i2c_acpi_new_device(struct device *dev, int index,
 				       struct i2c_board_info *info)
 {
 	struct i2c_acpi_lookup lookup;
 	struct i2c_adapter *adapter;
 	struct i2c_client *client;
 	struct acpi_device *adev;
 	LIST_HEAD(resource_list);
 	int ret;

 	adev = ACPI_COMPANION(dev);
 	if (!adev)
 		return ERR_PTR(-EINVAL);

 	memset(&lookup, 0, sizeof(lookup));
 	lookup.info = info;
 	lookup.device_handle = acpi_device_handle(adev);
 	lookup.index = index;

 	ret = acpi_dev_get_resources(adev, &resource_list,
 				     i2c_acpi_fill_info, &lookup);
 	if (ret < 0)
 		return ERR_PTR(ret);

 	acpi_dev_free_resource_list(&resource_list);

 	if (!info->addr)
 		return ERR_PTR(-EADDRNOTAVAIL);

 	adapter = i2c_acpi_find_adapter_by_handle(lookup.adapter_handle);
 	if (!adapter)
 		return ERR_PTR(-EPROBE_DEFER);

 	client = i2c_new_device(adapter, info);
 	if (!client)
 		return ERR_PTR(-ENODEV);

 	return client;
 }
 EXPORT_SYMBOL_GPL(i2c_acpi_new_device);

 #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) {
 		/* Getting a NACK is unfortunately normal with some DSTDs */
 		if (ret == -EREMOTEIO)
 			dev_dbg(&client->adapter->dev, "i2c read %d bytes from client@%#x starting at reg %#x failed, error: %d\n",
 				data_len, client->addr, cmd, ret);
 		else
 			dev_err(&client->adapter->dev, "i2c read %d bytes from client@%#x starting at reg %#x failed, error: %d\n",
 				data_len, client->addr, cmd, ret);
 	/* 2 transfers must have completed successfully */
 	} else if (ret == 2) {
 		memcpy(data, buffer, data_len);
 		ret = 0;
 	} else {
 		ret = -EIO;
 	}

 	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));

 	kfree(buffer);

 	if (ret < 0) {
 		dev_err(&client->adapter->dev, "i2c write failed: %d\n", ret);
 		return ret;
 	}

 	/* 1 transfer must have completed successfully */
 	return (ret == 1) ? 0 : -EIO;
 }

 static acpi_status
 i2c_acpi_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 i2c_acpi_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;

 	client = kzalloc(sizeof(*client), GFP_KERNEL);
 	if (!client) {
 		ret = AE_NO_MEMORY;
 		goto err;
 	}

 	if (!value64 || !i2c_acpi_get_i2c_resource(ares, &sb)) {
 		ret = AE_BAD_PARAMETER;
 		goto err;
 	}

 	client->adapter = adapter;
 	client->addr = sb->slave_address;

 	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);
 		} else {
 			status = acpi_gsb_i2c_write_bytes(client, command,
 					gsb->data, info->access_length);
 		}
 		break;

 	default:
 		dev_warn(&adapter->dev, "protocol 0x%02x not supported for client 0x%02x\n",
 			 accessor_type, client->addr);
 		ret = AE_BAD_PARAMETER;
 		goto err;
 	}

 	gsb->status = status;

  err:
 	kfree(client);
 	ACPI_FREE(ares);
 	return ret;
 }


 int i2c_acpi_install_space_handler(struct i2c_adapter *adapter)
 {
 	acpi_handle handle;
 	struct i2c_acpi_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 i2c_acpi_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,
 				&i2c_acpi_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;
 }

 void i2c_acpi_remove_space_handler(struct i2c_adapter *adapter)
 {
 	acpi_handle handle;
 	struct i2c_acpi_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,
 				&i2c_acpi_space_handler);

 	status = acpi_bus_get_private_data(handle, (void **)&data);
 	if (ACPI_SUCCESS(status))
 		kfree(data);

 	acpi_bus_detach_private_data(handle);
 }
 #endif /* CONFIG_ACPI_I2C_OPREGION */
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Linux I2C core ACPI support code
	*
	* Copyright (C) 2014 Intel Corp, Author: Lan Tianyu <[email protected]>
	*/

	#include <linux/acpi.h>
	#include <linux/device.h>
	#include <linux/err.h>
	#include <linux/i2c.h>
	#include <linux/list.h>
	#include <linux/module.h>
	#include <linux/slab.h>

	#include "i2c-core.h"

	struct i2c_acpi_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;

	struct i2c_acpi_lookup {
	struct i2c_board_info *info;
	acpi_handle adapter_handle;
	acpi_handle device_handle;
	acpi_handle search_handle;
	int n;
	int index;
	u32 speed;
	u32 min_speed;
	};

	/**
	* i2c_acpi_get_i2c_resource - Gets I2cSerialBus resource if type matches
	* @ares: ACPI resource
	* @i2c: Pointer to I2cSerialBus resource will be returned here
	*
	* Checks if the given ACPI resource is of type I2cSerialBus.
	* In this case, returns a pointer to it to the caller.
	*
	* Returns true if resource type is of I2cSerialBus, otherwise false.
	*/
	bool i2c_acpi_get_i2c_resource(struct acpi_resource *ares,
	struct acpi_resource_i2c_serialbus **i2c)
	{
	struct acpi_resource_i2c_serialbus *sb;

	if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
	return false;

	sb = &ares->data.i2c_serial_bus;
	if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_I2C)
	return false;

	*i2c = sb;
	return true;
	}
	EXPORT_SYMBOL_GPL(i2c_acpi_get_i2c_resource);

	static int i2c_acpi_fill_info(struct acpi_resource ares, void data)
	{
	struct i2c_acpi_lookup *lookup = data;
	struct i2c_board_info *info = lookup->info;
	struct acpi_resource_i2c_serialbus *sb;
	acpi_status status;

	if (info->addr \|\| !i2c_acpi_get_i2c_resource(ares, &sb))
	return 1;

	if (lookup->index != -1 && lookup->n++ != lookup->index)
	return 1;

	status = acpi_get_handle(lookup->device_handle,
	sb->resource_source.string_ptr,
	&lookup->adapter_handle);
	if (ACPI_FAILURE(status))
	return 1;

	info->addr = sb->slave_address;
	lookup->speed = sb->connection_speed;
	if (sb->access_mode == ACPI_I2C_10BIT_MODE)
	info->flags \|= I2C_CLIENT_TEN;

	return 1;
	}

	static const struct acpi_device_id i2c_acpi_ignored_device_ids[] = {
	/*
	* ACPI video acpi_devices, which are handled by the acpi-video driver
	* sometimes contain a SERIAL_TYPE_I2C ACPI resource, ignore these.
	*/
	{ ACPI_VIDEO_HID, 0 },
	{}
	};

	static int i2c_acpi_do_lookup(struct acpi_device *adev,
	struct i2c_acpi_lookup *lookup)
	{
	struct i2c_board_info *info = lookup->info;
	struct list_head resource_list;
	int ret;

	if (acpi_bus_get_status(adev) \|\| !adev->status.present)
	return -EINVAL;

	if (acpi_match_device_ids(adev, i2c_acpi_ignored_device_ids) == 0)
	return -ENODEV;

	memset(info, 0, sizeof(*info));
	lookup->device_handle = acpi_device_handle(adev);

	/* Look up for I2cSerialBus resource */
	INIT_LIST_HEAD(&resource_list);
	ret = acpi_dev_get_resources(adev, &resource_list,
	i2c_acpi_fill_info, lookup);
	acpi_dev_free_resource_list(&resource_list);

	if (ret < 0 \|\| !info->addr)
	return -EINVAL;

	return 0;
	}

	static int i2c_acpi_get_info(struct acpi_device *adev,
	struct i2c_board_info *info,
	struct i2c_adapter *adapter,
	acpi_handle *adapter_handle)
	{
	struct list_head resource_list;
	struct resource_entry *entry;
	struct i2c_acpi_lookup lookup;
	int ret;

	memset(&lookup, 0, sizeof(lookup));
	lookup.info = info;
	lookup.index = -1;

	if (acpi_device_enumerated(adev))
	return -EINVAL;

	ret = i2c_acpi_do_lookup(adev, &lookup);
	if (ret)
	return ret;

	if (adapter) {
	/* The adapter must match the one in I2cSerialBus() connector */
	if (ACPI_HANDLE(&adapter->dev) != lookup.adapter_handle)
	return -ENODEV;
	} else {
	struct acpi_device *adapter_adev;

	/* The adapter must be present */
	if (acpi_bus_get_device(lookup.adapter_handle, &adapter_adev))
	return -ENODEV;
	if (acpi_bus_get_status(adapter_adev) \|\|
	!adapter_adev->status.present)
	return -ENODEV;
	}

	info->fwnode = acpi_fwnode_handle(adev);
	if (adapter_handle)
	*adapter_handle = lookup.adapter_handle;

	/* Then fill IRQ number if any */
	INIT_LIST_HEAD(&resource_list);
	ret = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
	if (ret < 0)
	return -EINVAL;

	resource_list_for_each_entry(entry, &resource_list) {
	if (resource_type(entry->res) == IORESOURCE_IRQ) {
	info->irq = entry->res->start;
	break;
	}
	}

	acpi_dev_free_resource_list(&resource_list);

	acpi_set_modalias(adev, dev_name(&adev->dev), info->type,
	sizeof(info->type));

	return 0;
	}

	static void i2c_acpi_register_device(struct i2c_adapter *adapter,
	struct acpi_device *adev,
	struct i2c_board_info *info)
	{
	adev->power.flags.ignore_parent = true;
	acpi_device_set_enumerated(adev);

	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));
	}
	}

	static acpi_status i2c_acpi_add_device(acpi_handle handle, u32 level,
	void data, void *return_value)
	{
	struct i2c_adapter *adapter = data;
	struct acpi_device *adev;
	struct i2c_board_info info;

	if (acpi_bus_get_device(handle, &adev))
	return AE_OK;

	if (i2c_acpi_get_info(adev, &info, adapter, NULL))
	return AE_OK;

	i2c_acpi_register_device(adapter, adev, &info);

	return AE_OK;
	}

	#define I2C_ACPI_MAX_SCAN_DEPTH 32

	/**
	* i2c_acpi_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.
	*/
	void i2c_acpi_register_devices(struct i2c_adapter *adap)
	{
	acpi_status status;

	if (!has_acpi_companion(&adap->dev))
	return;

	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
	I2C_ACPI_MAX_SCAN_DEPTH,
	i2c_acpi_add_device, NULL,
	adap, NULL);
	if (ACPI_FAILURE(status))
	dev_warn(&adap->dev, "failed to enumerate I2C slaves\n");
	}

	const struct acpi_device_id *
	i2c_acpi_match_device(const struct acpi_device_id *matches,
	struct i2c_client *client)
	{
	if (!(client && matches))
	return NULL;

	return acpi_match_device(matches, &client->dev);
	}

	static acpi_status i2c_acpi_lookup_speed(acpi_handle handle, u32 level,
	void data, void *return_value)
	{
	struct i2c_acpi_lookup *lookup = data;
	struct acpi_device *adev;

	if (acpi_bus_get_device(handle, &adev))
	return AE_OK;

	if (i2c_acpi_do_lookup(adev, lookup))
	return AE_OK;

	if (lookup->search_handle != lookup->adapter_handle)
	return AE_OK;

	if (lookup->speed <= lookup->min_speed)
	lookup->min_speed = lookup->speed;

	return AE_OK;
	}

	/**
	* i2c_acpi_find_bus_speed - find I2C bus speed from ACPI
	* @dev: The device owning the bus
	*
	* Find the I2C bus speed by walking the ACPI namespace for all I2C slaves
	* devices connected to this bus and use the speed of slowest device.
	*
	* Returns the speed in Hz or zero
	*/
	u32 i2c_acpi_find_bus_speed(struct device *dev)
	{
	struct i2c_acpi_lookup lookup;
	struct i2c_board_info dummy;
	acpi_status status;

	if (!has_acpi_companion(dev))
	return 0;

	memset(&lookup, 0, sizeof(lookup));
	lookup.search_handle = ACPI_HANDLE(dev);
	lookup.min_speed = UINT_MAX;
	lookup.info = &dummy;
	lookup.index = -1;

	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
	I2C_ACPI_MAX_SCAN_DEPTH,
	i2c_acpi_lookup_speed, NULL,
	&lookup, NULL);

	if (ACPI_FAILURE(status)) {
	dev_warn(dev, "unable to find I2C bus speed from ACPI\n");
	return 0;
	}

	return lookup.min_speed != UINT_MAX ? lookup.min_speed : 0;
	}
	EXPORT_SYMBOL_GPL(i2c_acpi_find_bus_speed);

	static int i2c_acpi_find_match_adapter(struct device dev, void data)
	{
	struct i2c_adapter *adapter = i2c_verify_adapter(dev);

	if (!adapter)
	return 0;

	return ACPI_HANDLE(dev) == (acpi_handle)data;
	}

	static int i2c_acpi_find_match_device(struct device dev, void data)
	{
	return ACPI_COMPANION(dev) == data;
	}

	struct i2c_adapter *i2c_acpi_find_adapter_by_handle(acpi_handle handle)
	{
	struct device *dev;

	dev = bus_find_device(&i2c_bus_type, NULL, handle,
	i2c_acpi_find_match_adapter);
	return dev ? i2c_verify_adapter(dev) : NULL;
	}
	EXPORT_SYMBOL_GPL(i2c_acpi_find_adapter_by_handle);

	static struct i2c_client i2c_acpi_find_client_by_adev(struct acpi_device adev)
	{
	struct device *dev;

	dev = bus_find_device(&i2c_bus_type, NULL, adev,
	i2c_acpi_find_match_device);
	return dev ? i2c_verify_client(dev) : NULL;
	}

	static int i2c_acpi_notify(struct notifier_block *nb, unsigned long value,
	void *arg)
	{
	struct acpi_device *adev = arg;
	struct i2c_board_info info;
	acpi_handle adapter_handle;
	struct i2c_adapter *adapter;
	struct i2c_client *client;

	switch (value) {
	case ACPI_RECONFIG_DEVICE_ADD:
	if (i2c_acpi_get_info(adev, &info, NULL, &adapter_handle))
	break;

	adapter = i2c_acpi_find_adapter_by_handle(adapter_handle);
	if (!adapter)
	break;

	i2c_acpi_register_device(adapter, adev, &info);
	break;
	case ACPI_RECONFIG_DEVICE_REMOVE:
	if (!acpi_device_enumerated(adev))
	break;

	client = i2c_acpi_find_client_by_adev(adev);
	if (!client)
	break;

	i2c_unregister_device(client);
	put_device(&client->dev);
	break;
	}

	return NOTIFY_OK;
	}

	struct notifier_block i2c_acpi_notifier = {
	.notifier_call = i2c_acpi_notify,
	};

	/**
	* i2c_acpi_new_device - Create i2c-client for the Nth I2cSerialBus resource
	* @dev: Device owning the ACPI resources to get the client from
	* @index: Index of ACPI resource to get
	* @info: describes the I2C device; note this is modified (addr gets set)
	* Context: can sleep
	*
	* By default the i2c subsys creates an i2c-client for the first I2cSerialBus
	* resource of an acpi_device, but some acpi_devices have multiple I2cSerialBus
	* resources, in that case this function can be used to create an i2c-client
	* for other I2cSerialBus resources in the Current Resource Settings table.
	*
	* Also see i2c_new_device, which this function calls to create the i2c-client.
	*
	* Returns a pointer to the new i2c-client, or error pointer in case of failure.
	* Specifically, -EPROBE_DEFER is returned if the adapter is not found.
	*/
	struct i2c_client i2c_acpi_new_device(struct device dev, int index,
	struct i2c_board_info *info)
	{
	struct i2c_acpi_lookup lookup;
	struct i2c_adapter *adapter;
	struct i2c_client *client;
	struct acpi_device *adev;
	LIST_HEAD(resource_list);
	int ret;

	adev = ACPI_COMPANION(dev);
	if (!adev)
	return ERR_PTR(-EINVAL);

	memset(&lookup, 0, sizeof(lookup));
	lookup.info = info;
	lookup.device_handle = acpi_device_handle(adev);
	lookup.index = index;

	ret = acpi_dev_get_resources(adev, &resource_list,
	i2c_acpi_fill_info, &lookup);
	if (ret < 0)
	return ERR_PTR(ret);

	acpi_dev_free_resource_list(&resource_list);

	if (!info->addr)
	return ERR_PTR(-EADDRNOTAVAIL);

	adapter = i2c_acpi_find_adapter_by_handle(lookup.adapter_handle);
	if (!adapter)
	return ERR_PTR(-EPROBE_DEFER);

	client = i2c_new_device(adapter, info);
	if (!client)
	return ERR_PTR(-ENODEV);

	return client;
	}
	EXPORT_SYMBOL_GPL(i2c_acpi_new_device);

	#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) {
	/* Getting a NACK is unfortunately normal with some DSTDs */
	if (ret == -EREMOTEIO)
	dev_dbg(&client->adapter->dev, "i2c read %d bytes from client@%#x starting at reg %#x failed, error: %d\n",
	data_len, client->addr, cmd, ret);
	else
	dev_err(&client->adapter->dev, "i2c read %d bytes from client@%#x starting at reg %#x failed, error: %d\n",
	data_len, client->addr, cmd, ret);
	/* 2 transfers must have completed successfully */
	} else if (ret == 2) {
	memcpy(data, buffer, data_len);
	ret = 0;
	} else {
	ret = -EIO;
	}

	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));

	kfree(buffer);

	if (ret < 0) {
	dev_err(&client->adapter->dev, "i2c write failed: %d\n", ret);
	return ret;
	}

	/* 1 transfer must have completed successfully */
	return (ret == 1) ? 0 : -EIO;
	}

	static acpi_status
	i2c_acpi_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 i2c_acpi_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;

	client = kzalloc(sizeof(*client), GFP_KERNEL);
	if (!client) {
	ret = AE_NO_MEMORY;
	goto err;
	}

	if (!value64 \|\| !i2c_acpi_get_i2c_resource(ares, &sb)) {
	ret = AE_BAD_PARAMETER;
	goto err;
	}

	client->adapter = adapter;
	client->addr = sb->slave_address;

	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);
	} else {
	status = acpi_gsb_i2c_write_bytes(client, command,
	gsb->data, info->access_length);
	}
	break;

	default:
	dev_warn(&adapter->dev, "protocol 0x%02x not supported for client 0x%02x\n",
	accessor_type, client->addr);
	ret = AE_BAD_PARAMETER;
	goto err;
	}

	gsb->status = status;

	err:
	kfree(client);
	ACPI_FREE(ares);
	return ret;
	}


	int i2c_acpi_install_space_handler(struct i2c_adapter *adapter)
	{
	acpi_handle handle;
	struct i2c_acpi_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 i2c_acpi_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,
	&i2c_acpi_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;
	}

	void i2c_acpi_remove_space_handler(struct i2c_adapter *adapter)
	{
	acpi_handle handle;
	struct i2c_acpi_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,
	&i2c_acpi_space_handler);

	status = acpi_bus_get_private_data(handle, (void **)&data);
	if (ACPI_SUCCESS(status))
	kfree(data);

	acpi_bus_detach_private_data(handle);
	}
	#endif /* CONFIG_ACPI_I2C_OPREGION */