1. 根目录:
2. drivers
3. acpi
4. acpi_i2c.c

/*
 * ACPI I2C enumeration support
 *
 * Copyright (C) 2012, Intel Corporation
 * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/acpi.h>
#include <linux/device.h>
#include <linux/export.h>
#include <linux/i2c.h>
#include <linux/ioport.h>

ACPI_MODULE_NAME("i2c");

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 (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.acpi_node.handle = handle;
	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;

	strlcpy(info.type, dev_name(&adev->dev), sizeof(info.type));
	if (!i2c_new_device(adapter, &info)) {
		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
 * @adapter: 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 acpi_i2c_register_devices(struct i2c_adapter *adapter)
{
	acpi_handle handle;
	acpi_status status;

	handle = ACPI_HANDLE(adapter->dev.parent);
	if (!handle)
		return;

	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
				     acpi_i2c_add_device, NULL,
				     adapter, NULL);
	if (ACPI_FAILURE(status))
		dev_warn(&adapter->dev, "failed to enumerate I2C slaves\n");
}
EXPORT_SYMBOL_GPL(acpi_i2c_register_devices);