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/*
* Dell WMI descriptor driver
*
* Copyright (C) 2017 Dell Inc. All Rights Reserved.
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/acpi.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/wmi.h>
#include "dell-wmi-descriptor.h"
#define DELL_WMI_DESCRIPTOR_GUID "8D9DDCBC-A997-11DA-B012-B622A1EF5492"
struct descriptor_priv {
struct list_head list;
u32 interface_version;
u32 size;
};
static int descriptor_valid = -EPROBE_DEFER;
static LIST_HEAD(wmi_list);
static DEFINE_MUTEX(list_mutex);
int dell_wmi_get_descriptor_valid(void)
{
if (!wmi_has_guid(DELL_WMI_DESCRIPTOR_GUID))
return -ENODEV;
return descriptor_valid;
}
EXPORT_SYMBOL_GPL(dell_wmi_get_descriptor_valid);
bool dell_wmi_get_interface_version(u32 *version)
{
struct descriptor_priv *priv;
bool ret = false;
mutex_lock(&list_mutex);
priv = list_first_entry_or_null(&wmi_list,
struct descriptor_priv,
list);
if (priv) {
*version = priv->interface_version;
ret = true;
}
mutex_unlock(&list_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(dell_wmi_get_interface_version);
bool dell_wmi_get_size(u32 *size)
{
struct descriptor_priv *priv;
bool ret = false;
mutex_lock(&list_mutex);
priv = list_first_entry_or_null(&wmi_list,
struct descriptor_priv,
list);
if (priv) {
*size = priv->size;
ret = true;
}
mutex_unlock(&list_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(dell_wmi_get_size);
/*
* Descriptor buffer is 128 byte long and contains:
*
* Name Offset Length Value
* Vendor Signature 0 4 "DELL"
* Object Signature 4 4 " WMI"
* WMI Interface Version 8 4 <version>
* WMI buffer length 12 4 <length>
*/
static int dell_wmi_descriptor_probe(struct wmi_device *wdev)
{
union acpi_object *obj = NULL;
struct descriptor_priv *priv;
u32 *buffer;
int ret;
obj = wmidev_block_query(wdev, 0);
if (!obj) {
dev_err(&wdev->dev, "failed to read Dell WMI descriptor\n");
ret = -EIO;
goto out;
}
if (obj->type != ACPI_TYPE_BUFFER) {
dev_err(&wdev->dev, "Dell descriptor has wrong type\n");
ret = -EINVAL;
descriptor_valid = ret;
goto out;
}
/* Although it's not technically a failure, this would lead to
* unexpected behavior
*/
if (obj->buffer.length != 128) {
dev_err(&wdev->dev,
"Dell descriptor buffer has unexpected length (%d)\n",
obj->buffer.length);
ret = -EINVAL;
descriptor_valid = ret;
goto out;
}
buffer = (u32 *)obj->buffer.pointer;
if (strncmp(obj->string.pointer, "DELL WMI", 8) != 0) {
dev_err(&wdev->dev, "Dell descriptor buffer has invalid signature (%8ph)\n",
buffer);
ret = -EINVAL;
descriptor_valid = ret;
goto out;
}
descriptor_valid = 0;
if (buffer[2] != 0 && buffer[2] != 1)
dev_warn(&wdev->dev, "Dell descriptor buffer has unknown version (%lu)\n",
(unsigned long) buffer[2]);
priv = devm_kzalloc(&wdev->dev, sizeof(struct descriptor_priv),
GFP_KERNEL);
if (!priv) {
ret = -ENOMEM;
goto out;
}
priv->interface_version = buffer[2];
priv->size = buffer[3];
ret = 0;
dev_set_drvdata(&wdev->dev, priv);
mutex_lock(&list_mutex);
list_add_tail(&priv->list, &wmi_list);
mutex_unlock(&list_mutex);
dev_dbg(&wdev->dev, "Detected Dell WMI interface version %lu and buffer size %lu\n",
(unsigned long) priv->interface_version,
(unsigned long) priv->size);
out:
kfree(obj);
return ret;
}
static int dell_wmi_descriptor_remove(struct wmi_device *wdev)
{
struct descriptor_priv *priv = dev_get_drvdata(&wdev->dev);
mutex_lock(&list_mutex);
list_del(&priv->list);
mutex_unlock(&list_mutex);
return 0;
}
static const struct wmi_device_id dell_wmi_descriptor_id_table[] = {
{ .guid_string = DELL_WMI_DESCRIPTOR_GUID },
{ },
};
static struct wmi_driver dell_wmi_descriptor_driver = {
.driver = {
.name = "dell-wmi-descriptor",
},
.probe = dell_wmi_descriptor_probe,
.remove = dell_wmi_descriptor_remove,
.id_table = dell_wmi_descriptor_id_table,
};
module_wmi_driver(dell_wmi_descriptor_driver);
MODULE_ALIAS("wmi:" DELL_WMI_DESCRIPTOR_GUID);
MODULE_AUTHOR("Mario Limonciello <mario.limonciello@dell.com>");
MODULE_DESCRIPTION("Dell WMI descriptor driver");
MODULE_LICENSE("GPL");
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