drivers/platform/x86/wmi-bmof.c

   1 /*
   2  * WMI embedded Binary MOF driver
   3  *
   4  * Copyright (c) 2015 Andrew Lutomirski
   5  * Copyright (C) 2017 VMware, Inc. All Rights Reserved.
   6  *
   7  *  This program is free software; you can redistribute it and/or modify it
   8  *  under the terms of the GNU General Public License version 2 as published
   9  *  by the Free Software Foundation.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  */
  16
  17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  18
  19 #include <linux/acpi.h>
  20 #include <linux/device.h>
  21 #include <linux/fs.h>
  22 #include <linux/kernel.h>
  23 #include <linux/module.h>
  24 #include <linux/string.h>
  25 #include <linux/sysfs.h>
  26 #include <linux/types.h>
  27 #include <linux/wmi.h>
  28
  29 #define WMI_BMOF_GUID "05901221-D566-11D1-B2F0-00A0C9062910"
  30
  31 struct bmof_priv {
  32         union acpi_object *bmofdata;
  33         struct bin_attribute bmof_bin_attr;
  34 };
  35
  36 static ssize_t
  37 read_bmof(struct file *filp, struct kobject *kobj,
  38          struct bin_attribute *attr,
  39          char *buf, loff_t off, size_t count)
  40 {
  41         struct bmof_priv *priv =
  42                 container_of(attr, struct bmof_priv, bmof_bin_attr);
  43
  44         if (off < 0)
  45                 return -EINVAL;
  46
  47         if (off >= priv->bmofdata->buffer.length)
  48                 return 0;
  49
  50         if (count > priv->bmofdata->buffer.length - off)
  51                 count = priv->bmofdata->buffer.length - off;
  52
  53         memcpy(buf, priv->bmofdata->buffer.pointer + off, count);
  54         return count;
  55 }
  56
  57 static int wmi_bmof_probe(struct wmi_device *wdev)
  58 {
  59         struct bmof_priv *priv;
  60         int ret;
  61
  62         priv = devm_kzalloc(&wdev->dev, sizeof(struct bmof_priv), GFP_KERNEL);
  63         if (!priv)
  64                 return -ENOMEM;
  65
  66         dev_set_drvdata(&wdev->dev, priv);
  67
  68         priv->bmofdata = wmidev_block_query(wdev, 0);
  69         if (!priv->bmofdata) {
  70                 dev_err(&wdev->dev, "failed to read Binary MOF\n");
  71                 return -EIO;
  72         }
  73
  74         if (priv->bmofdata->type != ACPI_TYPE_BUFFER) {
  75                 dev_err(&wdev->dev, "Binary MOF is not a buffer\n");
  76                 ret = -EIO;
  77                 goto err_free;
  78         }
  79
  80         sysfs_bin_attr_init(&priv->bmof_bin_attr);
  81         priv->bmof_bin_attr.attr.name = "bmof";
  82         priv->bmof_bin_attr.attr.mode = 0400;
  83         priv->bmof_bin_attr.read = read_bmof;
  84         priv->bmof_bin_attr.size = priv->bmofdata->buffer.length;
  85
  86         ret = sysfs_create_bin_file(&wdev->dev.kobj, &priv->bmof_bin_attr);
  87         if (ret)
  88                 goto err_free;
  89
  90         return 0;
  91
  92  err_free:
  93         kfree(priv->bmofdata);
  94         return ret;
  95 }
  96
  97 static int wmi_bmof_remove(struct wmi_device *wdev)
  98 {
  99         struct bmof_priv *priv = dev_get_drvdata(&wdev->dev);
 100
 101         sysfs_remove_bin_file(&wdev->dev.kobj, &priv->bmof_bin_attr);
 102         kfree(priv->bmofdata);
 103         return 0;
 104 }
 105
 106 static const struct wmi_device_id wmi_bmof_id_table[] = {
 107         { .guid_string = WMI_BMOF_GUID },
 108         { },
 109 };
 110
 111 static struct wmi_driver wmi_bmof_driver = {
 112         .driver = {
 113                 .name = "wmi-bmof",
 114         },
 115         .probe = wmi_bmof_probe,
 116         .remove = wmi_bmof_remove,
 117         .id_table = wmi_bmof_id_table,
 118 };
 119
 120 module_wmi_driver(wmi_bmof_driver);
 121
 122 MODULE_ALIAS("wmi:" WMI_BMOF_GUID);
 123 MODULE_AUTHOR("Andrew Lutomirski <luto@kernel.org>");
 124 MODULE_DESCRIPTION("WMI embedded Binary MOF driver");
 125 MODULE_LICENSE("GPL");