drivers/platform/x86/dell-smbios-wmi.c

   1 /*
   2  *  WMI methods for use with dell-smbios
   3  *
   4  *  Copyright (c) 2017 Dell Inc.
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License version 2 as
   8  *  published by the Free Software Foundation.
   9  */
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12 #include <linux/dmi.h>
  13 #include <linux/list.h>
  14 #include <linux/module.h>
  15 #include <linux/mutex.h>
  16 #include <linux/uaccess.h>
  17 #include <linux/wmi.h>
  18 #include "dell-smbios.h"
  19 #include "dell-wmi-descriptor.h"
  20
  21 static DEFINE_MUTEX(call_mutex);
  22 static DEFINE_MUTEX(list_mutex);
  23 static int wmi_supported;
  24
  25 struct misc_bios_flags_structure {
  26         struct dmi_header header;
  27         u16 flags0;
  28 } __packed;
  29 #define FLAG_HAS_ACPI_WMI 0x02
  30
  31 #define DELL_WMI_SMBIOS_GUID "A80593CE-A997-11DA-B012-B622A1EF5492"
  32
  33 struct wmi_smbios_priv {
  34         struct dell_wmi_smbios_buffer *buf;
  35         struct list_head list;
  36         struct wmi_device *wdev;
  37         struct device *child;
  38         u32 req_buf_size;
  39 };
  40 static LIST_HEAD(wmi_list);
  41
  42 static inline struct wmi_smbios_priv *get_first_smbios_priv(void)
  43 {
  44         return list_first_entry_or_null(&wmi_list,
  45                                         struct wmi_smbios_priv,
  46                                         list);
  47 }
  48
  49 static int run_smbios_call(struct wmi_device *wdev)
  50 {
  51         struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
  52         struct wmi_smbios_priv *priv;
  53         struct acpi_buffer input;
  54         union acpi_object *obj;
  55         acpi_status status;
  56
  57         priv = dev_get_drvdata(&wdev->dev);
  58         input.length = priv->req_buf_size - sizeof(u64);
  59         input.pointer = &priv->buf->std;
  60
  61         dev_dbg(&wdev->dev, "evaluating: %u/%u [%x,%x,%x,%x]\n",
  62                 priv->buf->std.cmd_class, priv->buf->std.cmd_select,
  63                 priv->buf->std.input[0], priv->buf->std.input[1],
  64                 priv->buf->std.input[2], priv->buf->std.input[3]);
  65
  66         status = wmidev_evaluate_method(wdev, 0, 1, &input, &output);
  67         if (ACPI_FAILURE(status))
  68                 return -EIO;
  69         obj = (union acpi_object *)output.pointer;
  70         if (obj->type != ACPI_TYPE_BUFFER) {
  71                 dev_dbg(&wdev->dev, "received type: %d\n", obj->type);
  72                 if (obj->type == ACPI_TYPE_INTEGER)
  73                         dev_dbg(&wdev->dev, "SMBIOS call failed: %llu\n",
  74                                 obj->integer.value);
  75                 return -EIO;
  76         }
  77         memcpy(&priv->buf->std, obj->buffer.pointer, obj->buffer.length);
  78         dev_dbg(&wdev->dev, "result: [%08x,%08x,%08x,%08x]\n",
  79                 priv->buf->std.output[0], priv->buf->std.output[1],
  80                 priv->buf->std.output[2], priv->buf->std.output[3]);
  81
  82         return 0;
  83 }
  84
  85 static int dell_smbios_wmi_call(struct calling_interface_buffer *buffer)
  86 {
  87         struct wmi_smbios_priv *priv;
  88         size_t difference;
  89         size_t size;
  90         int ret;
  91
  92         mutex_lock(&call_mutex);
  93         priv = get_first_smbios_priv();
  94         if (!priv) {
  95                 ret = -ENODEV;
  96                 goto out_wmi_call;
  97         }
  98
  99         size = sizeof(struct calling_interface_buffer);
 100         difference = priv->req_buf_size - sizeof(u64) - size;
 101
 102         memset(&priv->buf->ext, 0, difference);
 103         memcpy(&priv->buf->std, buffer, size);
 104         ret = run_smbios_call(priv->wdev);
 105         memcpy(buffer, &priv->buf->std, size);
 106 out_wmi_call:
 107         mutex_unlock(&call_mutex);
 108
 109         return ret;
 110 }
 111
 112 static long dell_smbios_wmi_filter(struct wmi_device *wdev, unsigned int cmd,
 113                                    struct wmi_ioctl_buffer *arg)
 114 {
 115         struct wmi_smbios_priv *priv;
 116         int ret = 0;
 117
 118         switch (cmd) {
 119         case DELL_WMI_SMBIOS_CMD:
 120                 mutex_lock(&call_mutex);
 121                 priv = dev_get_drvdata(&wdev->dev);
 122                 if (!priv) {
 123                         ret = -ENODEV;
 124                         goto fail_smbios_cmd;
 125                 }
 126                 memcpy(priv->buf, arg, priv->req_buf_size);
 127                 if (dell_smbios_call_filter(&wdev->dev, &priv->buf->std)) {
 128                         dev_err(&wdev->dev, "Invalid call %d/%d:%8x\n",
 129                                 priv->buf->std.cmd_class,
 130                                 priv->buf->std.cmd_select,
 131                                 priv->buf->std.input[0]);
 132                         ret = -EFAULT;
 133                         goto fail_smbios_cmd;
 134                 }
 135                 ret = run_smbios_call(priv->wdev);
 136                 if (ret)
 137                         goto fail_smbios_cmd;
 138                 memcpy(arg, priv->buf, priv->req_buf_size);
 139 fail_smbios_cmd:
 140                 mutex_unlock(&call_mutex);
 141                 break;
 142         default:
 143                 ret = -ENOIOCTLCMD;
 144         }
 145         return ret;
 146 }
 147
 148 static int dell_smbios_wmi_probe(struct wmi_device *wdev)
 149 {
 150         struct wmi_driver *wdriver =
 151                 container_of(wdev->dev.driver, struct wmi_driver, driver);
 152         struct wmi_smbios_priv *priv;
 153         u32 hotfix;
 154         int count;
 155         int ret;
 156
 157         ret = dell_wmi_get_descriptor_valid();
 158         if (ret)
 159                 return ret;
 160
 161         priv = devm_kzalloc(&wdev->dev, sizeof(struct wmi_smbios_priv),
 162                             GFP_KERNEL);
 163         if (!priv)
 164                 return -ENOMEM;
 165
 166         /* WMI buffer size will be either 4k or 32k depending on machine */
 167         if (!dell_wmi_get_size(&priv->req_buf_size))
 168                 return -EPROBE_DEFER;
 169
 170         /* some SMBIOS calls fail unless BIOS contains hotfix */
 171         if (!dell_wmi_get_hotfix(&hotfix))
 172                 return -EPROBE_DEFER;
 173         if (!hotfix) {
 174                 dev_warn(&wdev->dev,
 175                         "WMI SMBIOS userspace interface not supported(%u), try upgrading to a newer BIOS\n",
 176                         hotfix);
 177                 wdriver->filter_callback = NULL;
 178         }
 179
 180         /* add in the length object we will use internally with ioctl */
 181         priv->req_buf_size += sizeof(u64);
 182         ret = set_required_buffer_size(wdev, priv->req_buf_size);
 183         if (ret)
 184                 return ret;
 185
 186         count = get_order(priv->req_buf_size);
 187         priv->buf = (void *)__get_free_pages(GFP_KERNEL, count);
 188         if (!priv->buf)
 189                 return -ENOMEM;
 190
 191         /* ID is used by dell-smbios to set priority of drivers */
 192         wdev->dev.id = 1;
 193         ret = dell_smbios_register_device(&wdev->dev, &dell_smbios_wmi_call);
 194         if (ret)
 195                 goto fail_register;
 196
 197         priv->wdev = wdev;
 198         dev_set_drvdata(&wdev->dev, priv);
 199         mutex_lock(&list_mutex);
 200         list_add_tail(&priv->list, &wmi_list);
 201         mutex_unlock(&list_mutex);
 202
 203         return 0;
 204
 205 fail_register:
 206         free_pages((unsigned long)priv->buf, count);
 207         return ret;
 208 }
 209
 210 static int dell_smbios_wmi_remove(struct wmi_device *wdev)
 211 {
 212         struct wmi_smbios_priv *priv = dev_get_drvdata(&wdev->dev);
 213         int count;
 214
 215         mutex_lock(&call_mutex);
 216         mutex_lock(&list_mutex);
 217         list_del(&priv->list);
 218         mutex_unlock(&list_mutex);
 219         dell_smbios_unregister_device(&wdev->dev);
 220         count = get_order(priv->req_buf_size);
 221         free_pages((unsigned long)priv->buf, count);
 222         mutex_unlock(&call_mutex);
 223         return 0;
 224 }
 225
 226 static const struct wmi_device_id dell_smbios_wmi_id_table[] = {
 227         { .guid_string = DELL_WMI_SMBIOS_GUID },
 228         { },
 229 };
 230
 231 static void parse_b1_table(const struct dmi_header *dm)
 232 {
 233         struct misc_bios_flags_structure *flags =
 234         container_of(dm, struct misc_bios_flags_structure, header);
 235
 236         /* 4 bytes header, 8 bytes flags */
 237         if (dm->length < 12)
 238                 return;
 239         if (dm->handle != 0xb100)
 240                 return;
 241         if ((flags->flags0 & FLAG_HAS_ACPI_WMI))
 242                 wmi_supported = 1;
 243 }
 244
 245 static void find_b1(const struct dmi_header *dm, void *dummy)
 246 {
 247         switch (dm->type) {
 248         case 0xb1: /* misc bios flags */
 249                 parse_b1_table(dm);
 250                 break;
 251         }
 252 }
 253
 254 static struct wmi_driver dell_smbios_wmi_driver = {
 255         .driver = {
 256                 .name = "dell-smbios",
 257         },
 258         .probe = dell_smbios_wmi_probe,
 259         .remove = dell_smbios_wmi_remove,
 260         .id_table = dell_smbios_wmi_id_table,
 261         .filter_callback = dell_smbios_wmi_filter,
 262 };
 263
 264 int init_dell_smbios_wmi(void)
 265 {
 266         dmi_walk(find_b1, NULL);
 267
 268         if (!wmi_supported)
 269                 return -ENODEV;
 270
 271         return wmi_driver_register(&dell_smbios_wmi_driver);
 272 }
 273
 274 void exit_dell_smbios_wmi(void)
 275 {
 276         wmi_driver_unregister(&dell_smbios_wmi_driver);
 277 }
 278
 279 MODULE_ALIAS("wmi:" DELL_WMI_SMBIOS_GUID);