linux/drivers/acpi/acpi_i2c.c
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   1/*
   2 * ACPI I2C enumeration support
   3 *
   4 * Copyright (C) 2012, Intel Corporation
   5 * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License version 2 as
   9 * published by the Free Software Foundation.
  10 */
  11
  12#include <linux/acpi.h>
  13#include <linux/device.h>
  14#include <linux/export.h>
  15#include <linux/i2c.h>
  16#include <linux/ioport.h>
  17
  18ACPI_MODULE_NAME("i2c");
  19
  20static int acpi_i2c_add_resource(struct acpi_resource *ares, void *data)
  21{
  22        struct i2c_board_info *info = data;
  23
  24        if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
  25                struct acpi_resource_i2c_serialbus *sb;
  26
  27                sb = &ares->data.i2c_serial_bus;
  28                if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_I2C) {
  29                        info->addr = sb->slave_address;
  30                        if (sb->access_mode == ACPI_I2C_10BIT_MODE)
  31                                info->flags |= I2C_CLIENT_TEN;
  32                }
  33        } else if (info->irq < 0) {
  34                struct resource r;
  35
  36                if (acpi_dev_resource_interrupt(ares, 0, &r))
  37                        info->irq = r.start;
  38        }
  39
  40        /* Tell the ACPI core to skip this resource */
  41        return 1;
  42}
  43
  44static acpi_status acpi_i2c_add_device(acpi_handle handle, u32 level,
  45                                       void *data, void **return_value)
  46{
  47        struct i2c_adapter *adapter = data;
  48        struct list_head resource_list;
  49        struct i2c_board_info info;
  50        struct acpi_device *adev;
  51        int ret;
  52
  53        if (acpi_bus_get_device(handle, &adev))
  54                return AE_OK;
  55        if (acpi_bus_get_status(adev) || !adev->status.present)
  56                return AE_OK;
  57
  58        memset(&info, 0, sizeof(info));
  59        info.acpi_node.handle = handle;
  60        info.irq = -1;
  61
  62        INIT_LIST_HEAD(&resource_list);
  63        ret = acpi_dev_get_resources(adev, &resource_list,
  64                                     acpi_i2c_add_resource, &info);
  65        acpi_dev_free_resource_list(&resource_list);
  66
  67        if (ret < 0 || !info.addr)
  68                return AE_OK;
  69
  70        strlcpy(info.type, dev_name(&adev->dev), sizeof(info.type));
  71        if (!i2c_new_device(adapter, &info)) {
  72                dev_err(&adapter->dev,
  73                        "failed to add I2C device %s from ACPI\n",
  74                        dev_name(&adev->dev));
  75        }
  76
  77        return AE_OK;
  78}
  79
  80/**
  81 * acpi_i2c_register_devices - enumerate I2C slave devices behind adapter
  82 * @adapter: pointer to adapter
  83 *
  84 * Enumerate all I2C slave devices behind this adapter by walking the ACPI
  85 * namespace. When a device is found it will be added to the Linux device
  86 * model and bound to the corresponding ACPI handle.
  87 */
  88void acpi_i2c_register_devices(struct i2c_adapter *adapter)
  89{
  90        acpi_handle handle;
  91        acpi_status status;
  92
  93        handle = ACPI_HANDLE(&adapter->dev);
  94        if (!handle)
  95                return;
  96
  97        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
  98                                     acpi_i2c_add_device, NULL,
  99                                     adapter, NULL);
 100        if (ACPI_FAILURE(status))
 101                dev_warn(&adapter->dev, "failed to enumerate I2C slaves\n");
 102}
 103EXPORT_SYMBOL_GPL(acpi_i2c_register_devices);
 104
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