diff options
Diffstat (limited to 'drivers/platform/x86/dell-wmi-descriptor.c')
| -rw-r--r-- | drivers/platform/x86/dell-wmi-descriptor.c | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/drivers/platform/x86/dell-wmi-descriptor.c b/drivers/platform/x86/dell-wmi-descriptor.c new file mode 100644 index 000000000000..4dfef1f53481 --- /dev/null +++ b/drivers/platform/x86/dell-wmi-descriptor.c @@ -0,0 +1,191 @@ +/* + * 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"); |