Commit 1a258e67 authored by Mario Limonciello's avatar Mario Limonciello Committed by Darren Hart (VMware)
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platform/x86: dell-smbios-wmi: Add new WMI dispatcher driver 



The dell-smbios stack only currently uses an SMI interface which grants
direct access to physical memory to the firmware SMM methods via a pointer.

This dispatcher driver adds a WMI-ACPI interface that is detected by WMI
probe and preferred over the SMI interface in dell-smbios.

Changing this to operate over WMI-ACPI will use an ACPI OperationRegion
for a buffer of data storage when SMM calls are performed.

This is a safer approach to use in kernel drivers as the SMM will
only have access to that OperationRegion.

Signed-off-by: default avatarMario Limonciello <mario.limonciello@dell.com>
Reviewed-by: default avatarEdward O'Callaghan <quasisec@google.com>
Signed-off-by: default avatarDarren Hart (VMware) <dvhart@infradead.org>
parent 549b4930

MAINTAINERS

+6 −0
Original line number Diff line number Diff line
@@ -3991,6 +3991,12 @@ L: platform-driver-x86@vger.kernel.org 
S:	Maintained

F:	drivers/platform/x86/dell-smbios-smm.c



DELL SMBIOS WMI DRIVER

M:	Mario Limonciello <mario.limonciello@dell.com>

L:	platform-driver-x86@vger.kernel.org

S:	Maintained

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



DELL LAPTOP DRIVER

M:	Matthew Garrett <mjg59@srcf.ucam.org>

M:	Pali Rohár <pali.rohar@gmail.com>

drivers/platform/x86/Kconfig

+14 −0
Original line number Diff line number Diff line
@@ -94,6 +94,20 @@ config ASUS_LAPTOP 
config DELL_SMBIOS

	tristate



config DELL_SMBIOS_WMI

	tristate "Dell SMBIOS calling interface (WMI implementation)"

	depends on ACPI_WMI

	select DELL_WMI_DESCRIPTOR

	default ACPI_WMI

	select DELL_SMBIOS

	---help---

	This provides an implementation for the Dell SMBIOS calling interface

	communicated over ACPI-WMI.



	If you have a Dell computer from >2007 you should say Y or M here.

	If you aren't sure and this module doesn't work for your computer

	it just won't load.



config DELL_SMBIOS_SMM

	tristate "Dell SMBIOS calling interface (SMM implementation)"

	depends on DCDBAS

drivers/platform/x86/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ obj-$(CONFIG_MSI_LAPTOP) += msi-laptop.o 
obj-$(CONFIG_ACPI_CMPC)		+= classmate-laptop.o

obj-$(CONFIG_COMPAL_LAPTOP)	+= compal-laptop.o

obj-$(CONFIG_DELL_SMBIOS)	+= dell-smbios.o

obj-$(CONFIG_DELL_SMBIOS_WMI)	+= dell-smbios-wmi.o

obj-$(CONFIG_DELL_SMBIOS_SMM)	+= dell-smbios-smm.o

obj-$(CONFIG_DELL_LAPTOP)	+= dell-laptop.o

obj-$(CONFIG_DELL_WMI)		+= dell-wmi.o

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

0 → 100644
+236 −0
Original line number Diff line number Diff line 
/*

 *  WMI methods for use with dell-smbios

 *

 *  Copyright (c) 2017 Dell Inc.

 *

 *  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.

 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt



#include <linux/dmi.h>

#include <linux/list.h>

#include <linux/module.h>

#include <linux/mutex.h>

#include <linux/uaccess.h>

#include <linux/wmi.h>

#include "dell-smbios.h"

#include "dell-wmi-descriptor.h"



static DEFINE_MUTEX(call_mutex);

static DEFINE_MUTEX(list_mutex);

static int wmi_supported;



struct misc_bios_flags_structure {

	struct dmi_header header;

	u16 flags0;

} __packed;

#define FLAG_HAS_ACPI_WMI 0x02



#define DELL_WMI_SMBIOS_GUID "A80593CE-A997-11DA-B012-B622A1EF5492"



struct dell_wmi_extensions {

	__u32 argattrib;

	__u32 blength;

	__u8 data[];

} __packed;



struct dell_wmi_smbios_buffer {

	struct calling_interface_buffer std;

	struct dell_wmi_extensions ext;

} __packed;



struct wmi_smbios_priv {

	struct dell_wmi_smbios_buffer *buf;

	struct list_head list;

	struct wmi_device *wdev;

	struct device *child;

	u32 req_buf_size;

};

static LIST_HEAD(wmi_list);



static inline struct wmi_smbios_priv *get_first_smbios_priv(void)

{

	return list_first_entry_or_null(&wmi_list,

					struct wmi_smbios_priv,

					list);

}



static int run_smbios_call(struct wmi_device *wdev)

{

	struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};

	struct wmi_smbios_priv *priv;

	struct acpi_buffer input;

	union acpi_object *obj;

	acpi_status status;



	priv = dev_get_drvdata(&wdev->dev);

	input.length = priv->req_buf_size - sizeof(u64);

	input.pointer = &priv->buf->std;



	dev_dbg(&wdev->dev, "evaluating: %u/%u [%x,%x,%x,%x]\n",

		priv->buf->std.cmd_class, priv->buf->std.cmd_select,

		priv->buf->std.input[0], priv->buf->std.input[1],

		priv->buf->std.input[2], priv->buf->std.input[3]);



	status = wmidev_evaluate_method(wdev, 0, 1, &input, &output);

	if (ACPI_FAILURE(status))

		return -EIO;

	obj = (union acpi_object *)output.pointer;

	if (obj->type != ACPI_TYPE_BUFFER) {

		dev_dbg(&wdev->dev, "received type: %d\n", obj->type);

		if (obj->type == ACPI_TYPE_INTEGER)

			dev_dbg(&wdev->dev, "SMBIOS call failed: %llu\n",

				obj->integer.value);

		return -EIO;

	}

	memcpy(&priv->buf->std, obj->buffer.pointer, obj->buffer.length);

	dev_dbg(&wdev->dev, "result: [%08x,%08x,%08x,%08x]\n",

		priv->buf->std.output[0], priv->buf->std.output[1],

		priv->buf->std.output[2], priv->buf->std.output[3]);



	return 0;

}



int dell_smbios_wmi_call(struct calling_interface_buffer *buffer)

{

	struct wmi_smbios_priv *priv;

	size_t difference;

	size_t size;

	int ret;



	mutex_lock(&call_mutex);

	priv = get_first_smbios_priv();

	if (!priv)

		return -ENODEV;



	size = sizeof(struct calling_interface_buffer);

	difference = priv->req_buf_size - sizeof(u64) - size;



	memset(&priv->buf->ext, 0, difference);

	memcpy(&priv->buf->std, buffer, size);

	ret = run_smbios_call(priv->wdev);

	memcpy(buffer, &priv->buf->std, size);

	mutex_unlock(&call_mutex);



	return ret;

}



static int dell_smbios_wmi_probe(struct wmi_device *wdev)

{

	struct wmi_smbios_priv *priv;

	int count;

	int ret;



	if (!wmi_has_guid(DELL_WMI_DESCRIPTOR_GUID))

		return -ENODEV;



	priv = devm_kzalloc(&wdev->dev, sizeof(struct wmi_smbios_priv),

			    GFP_KERNEL);

	if (!priv)

		return -ENOMEM;



	/* WMI buffer size will be either 4k or 32k depending on machine */

	if (!dell_wmi_get_size(&priv->req_buf_size))

		return -EPROBE_DEFER;



	count = get_order(priv->req_buf_size);

	priv->buf = (void *)__get_free_pages(GFP_KERNEL, count);

	if (!priv->buf)

		return -ENOMEM;



	/* ID is used by dell-smbios to set priority of drivers */

	wdev->dev.id = 1;

	ret = dell_smbios_register_device(&wdev->dev, &dell_smbios_wmi_call);

	if (ret)

		goto fail_register;



	priv->wdev = wdev;

	dev_set_drvdata(&wdev->dev, priv);

	mutex_lock(&list_mutex);

	list_add_tail(&priv->list, &wmi_list);

	mutex_unlock(&list_mutex);



	return 0;



fail_register:

	free_pages((unsigned long)priv->buf, count);

	return ret;

}



static int dell_smbios_wmi_remove(struct wmi_device *wdev)

{

	struct wmi_smbios_priv *priv = dev_get_drvdata(&wdev->dev);

	int count;



	mutex_lock(&call_mutex);

	mutex_lock(&list_mutex);

	list_del(&priv->list);

	mutex_unlock(&list_mutex);

	dell_smbios_unregister_device(&wdev->dev);

	count = get_order(priv->req_buf_size);

	free_pages((unsigned long)priv->buf, count);

	mutex_unlock(&call_mutex);

	return 0;

}



static const struct wmi_device_id dell_smbios_wmi_id_table[] = {

	{ .guid_string = DELL_WMI_SMBIOS_GUID },

	{ },

};



static void __init parse_b1_table(const struct dmi_header *dm)

{

	struct misc_bios_flags_structure *flags =

	container_of(dm, struct misc_bios_flags_structure, header);



	/* 4 bytes header, 8 bytes flags */

	if (dm->length < 12)

		return;

	if (dm->handle != 0xb100)

		return;

	if ((flags->flags0 & FLAG_HAS_ACPI_WMI))

		wmi_supported = 1;

}



static void __init find_b1(const struct dmi_header *dm, void *dummy)

{

	switch (dm->type) {

	case 0xb1: /* misc bios flags */

		parse_b1_table(dm);

		break;

	}

}



static struct wmi_driver dell_smbios_wmi_driver = {

	.driver = {

		.name = "dell-smbios",

	},

	.probe = dell_smbios_wmi_probe,

	.remove = dell_smbios_wmi_remove,

	.id_table = dell_smbios_wmi_id_table,

};



static int __init init_dell_smbios_wmi(void)

{

	dmi_walk(find_b1, NULL);



	if (!wmi_supported)

		return -ENODEV;



	return wmi_driver_register(&dell_smbios_wmi_driver);

}



static void __exit exit_dell_smbios_wmi(void)

{

	wmi_driver_unregister(&dell_smbios_wmi_driver);

}



module_init(init_dell_smbios_wmi);

module_exit(exit_dell_smbios_wmi);



MODULE_ALIAS("wmi:" DELL_WMI_SMBIOS_GUID);

MODULE_AUTHOR("Mario Limonciello <mario.limonciello@dell.com>");

MODULE_DESCRIPTION("Dell SMBIOS communications over WMI");

MODULE_LICENSE("GPL");

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