text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   * WMI embedded Binary MOF driver
   *
   * Copyright (c) 2015 Andrew Lutomirski
   * Copyright (C) 2017 VMware, Inc. All Rights Reserved.
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/acpi.h>
  #include <linux/device.h>
  #include <linux/fs.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/string.h>
  #include <linux/sysfs.h>
  #include <linux/types.h>
  #include <linux/wmi.h>
  
  #define WMI_BMOF_GUID "05901221-D566-11D1-B2F0-00A0C9062910"
  
  struct bmof_priv {
  	union acpi_object *bmofdata;
  	struct bin_attribute bmof_bin_attr;
  };
  
  static ssize_t
  read_bmof(struct file *filp, struct kobject *kobj,
  	 struct bin_attribute *attr,
  	 char *buf, loff_t off, size_t count)
  {
  	struct bmof_priv *priv =
  		container_of(attr, struct bmof_priv, bmof_bin_attr);
  
  	if (off < 0)
  		return -EINVAL;
  
  	if (off >= priv->bmofdata->buffer.length)
  		return 0;
  
  	if (count > priv->bmofdata->buffer.length - off)
  		count = priv->bmofdata->buffer.length - off;
  
  	memcpy(buf, priv->bmofdata->buffer.pointer + off, count);
  	return count;
  }
  
  static int wmi_bmof_probe(struct wmi_device *wdev, const void *context)
  {
  	struct bmof_priv *priv;
  	int ret;
  
  	priv = devm_kzalloc(&wdev->dev, sizeof(struct bmof_priv), GFP_KERNEL);
  	if (!priv)
  		return -ENOMEM;
  
  	dev_set_drvdata(&wdev->dev, priv);
  
  	priv->bmofdata = wmidev_block_query(wdev, 0);
  	if (!priv->bmofdata) {
  		dev_err(&wdev->dev, "failed to read Binary MOF\n");
  		return -EIO;
  	}
  
  	if (priv->bmofdata->type != ACPI_TYPE_BUFFER) {
  		dev_err(&wdev->dev, "Binary MOF is not a buffer\n");
  		ret = -EIO;
  		goto err_free;
  	}
  
  	sysfs_bin_attr_init(&priv->bmof_bin_attr);
  	priv->bmof_bin_attr.attr.name = "bmof";
  	priv->bmof_bin_attr.attr.mode = 0400;
  	priv->bmof_bin_attr.read = read_bmof;
  	priv->bmof_bin_attr.size = priv->bmofdata->buffer.length;
  
  	ret = sysfs_create_bin_file(&wdev->dev.kobj, &priv->bmof_bin_attr);
  	if (ret)
  		goto err_free;
  
  	return 0;
  
   err_free:
  	kfree(priv->bmofdata);
  	return ret;
  }
  
  static int wmi_bmof_remove(struct wmi_device *wdev)
  {
  	struct bmof_priv *priv = dev_get_drvdata(&wdev->dev);
  
  	sysfs_remove_bin_file(&wdev->dev.kobj, &priv->bmof_bin_attr);
  	kfree(priv->bmofdata);
  	return 0;
  }
  
  static const struct wmi_device_id wmi_bmof_id_table[] = {
  	{ .guid_string = WMI_BMOF_GUID },
  	{ },
  };
  
  static struct wmi_driver wmi_bmof_driver = {
  	.driver = {
  		.name = "wmi-bmof",
  	},
  	.probe = wmi_bmof_probe,
  	.remove = wmi_bmof_remove,
  	.id_table = wmi_bmof_id_table,
  };
  
  module_wmi_driver(wmi_bmof_driver);
  
  MODULE_DEVICE_TABLE(wmi, wmi_bmof_id_table);
  MODULE_AUTHOR("Andrew Lutomirski <luto@kernel.org>");
  MODULE_DESCRIPTION("WMI embedded Binary MOF driver");
  MODULE_LICENSE("GPL");
  