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Subject[PATCH 04/12] platform/x86: dell-smbios: Switch to a WMI-ACPI interface
Date
The driver currently uses an SMI interface which grants direct access
to physical memory to the platform via a pointer.

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

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

As a result, this change removes the dependency on this driver on the
dcdbas kernel module.

Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
---
drivers/platform/x86/Kconfig | 8 ++--
drivers/platform/x86/dell-smbios.c | 76 ++++++++++++++++++++++++++------------
drivers/platform/x86/dell-smbios.h | 11 +++---
3 files changed, 63 insertions(+), 32 deletions(-)

diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 9e52f05daa2e..81d61c0f4ef8 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -92,13 +92,13 @@ config ASUS_LAPTOP
If you have an ACPI-compatible ASUS laptop, say Y or M here.

config DELL_SMBIOS
- tristate
- select DCDBAS
+ tristate "Dell WMI SMBIOS calling interface"
+ depends on ACPI_WMI
---help---
This module provides common functions for kernel modules using
- Dell SMBIOS.
+ Dell SMBIOS over ACPI-WMI.

- If you have a Dell laptop, say Y or M here.
+ If you have a Dell computer, say Y or M here.

config DELL_LAPTOP
tristate "Dell Laptop Extras"
diff --git a/drivers/platform/x86/dell-smbios.c b/drivers/platform/x86/dell-smbios.c
index e9b1ca07c872..c06262a89169 100644
--- a/drivers/platform/x86/dell-smbios.c
+++ b/drivers/platform/x86/dell-smbios.c
@@ -4,6 +4,7 @@
* Copyright (c) Red Hat <mjg@redhat.com>
* Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@gmail.com>
* Copyright (c) 2014 Pali Rohár <pali.rohar@gmail.com>
+ * Copyright (c) 2017 Dell Inc.
*
* Based on documentation in the libsmbios package:
* Copyright (C) 2005-2014 Dell Inc.
@@ -18,13 +19,12 @@
#include <linux/module.h>
#include <linux/dmi.h>
#include <linux/err.h>
-#include <linux/gfp.h>
#include <linux/mutex.h>
-#include <linux/slab.h>
-#include <linux/io.h>
-#include "../../firmware/dcdbas.h"
+#include <linux/wmi.h>
#include "dell-smbios.h"

+#define DELL_WMI_SMBIOS_GUID "A80593CE-A997-11DA-B012-B622A1EF5492"
+
struct calling_interface_structure {
struct dmi_header header;
u16 cmdIOAddress;
@@ -76,20 +76,39 @@ void dell_smbios_release_buffer(void)
}
EXPORT_SYMBOL_GPL(dell_smbios_release_buffer);

-void dell_smbios_send_request(int class, int select)
+int run_wmi_smbios_call(struct calling_interface_buffer *buffer)
{
- struct smi_cmd command;
+ struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
+ struct acpi_buffer input;
+ union acpi_object *obj;
+ acpi_status status;
+
+ input.length = sizeof(struct calling_interface_buffer);
+ input.pointer = buffer;
+
+ status = wmi_evaluate_method(DELL_WMI_SMBIOS_GUID,
+ 0, 1, &input, &output);
+ if (ACPI_FAILURE(status)) {
+ pr_err("%x/%x [%x,%x,%x,%x] call failed\n",
+ buffer->class, buffer->select, buffer->input[0],
+ buffer->input[1], buffer->input[2], buffer->input[3]);
+ return -EIO;
+ }
+ obj = (union acpi_object *)output.pointer;
+ if (obj->type != ACPI_TYPE_BUFFER) {
+ pr_err("invalid type : %d\n", obj->type);
+ return -EIO;
+ }
+ memcpy(buffer, obj->buffer.pointer, input.length);

- command.magic = SMI_CMD_MAGIC;
- command.command_address = da_command_address;
- command.command_code = da_command_code;
- command.ebx = virt_to_phys(buffer);
- command.ecx = 0x42534931;
+ return 0;
+}

+void dell_smbios_send_request(int class, int select)
+{
buffer->class = class;
buffer->select = select;
-
- dcdbas_smi_request(&command);
+ run_wmi_smbios_call(buffer);
}
EXPORT_SYMBOL_GPL(dell_smbios_send_request);

@@ -170,7 +189,7 @@ static void __init find_tokens(const struct dmi_header *dm, void *dummy)
}
}

-static int __init dell_smbios_init(void)
+static int dell_smbios_probe(struct wmi_device *wdev)
{
int ret;

@@ -181,11 +200,7 @@ static int __init dell_smbios_init(void)
return -ENODEV;
}

- /*
- * Allocate buffer below 4GB for SMI data--only 32-bit physical addr
- * is passed to SMI handler.
- */
- buffer = (void *)__get_free_page(GFP_KERNEL | GFP_DMA32);
+ buffer = (void *)__get_free_page(GFP_KERNEL);
if (!buffer) {
ret = -ENOMEM;
goto fail_buffer;
@@ -198,17 +213,32 @@ static int __init dell_smbios_init(void)
return ret;
}

-static void __exit dell_smbios_exit(void)
+static int dell_smbios_remove(struct wmi_device *wdev)
{
kfree(da_tokens);
free_page((unsigned long)buffer);
+ return 0;
}

-subsys_initcall(dell_smbios_init);
-module_exit(dell_smbios_exit);
+static const struct wmi_device_id dell_smbios_id_table[] = {
+ { .guid_string = DELL_WMI_SMBIOS_GUID },
+ { },
+};
+
+static struct wmi_driver dell_smbios_driver = {
+ .driver = {
+ .name = "dell-smbios",
+ },
+ .probe = dell_smbios_probe,
+ .remove = dell_smbios_remove,
+ .id_table = dell_smbios_id_table,
+};
+module_wmi_driver(dell_smbios_driver);
+

MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
MODULE_AUTHOR("Gabriele Mazzotta <gabriele.mzt@gmail.com>");
MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
-MODULE_DESCRIPTION("Common functions for kernel modules using Dell SMBIOS");
+MODULE_AUTHOR("Mario Limonciello <mario.limonciello@dell.com>");
+MODULE_DESCRIPTION("Common functions for kernel modules using Dell SMBIOS over WMI");
MODULE_LICENSE("GPL");
diff --git a/drivers/platform/x86/dell-smbios.h b/drivers/platform/x86/dell-smbios.h
index 45cbc2292cd3..e1e29697b362 100644
--- a/drivers/platform/x86/dell-smbios.h
+++ b/drivers/platform/x86/dell-smbios.h
@@ -4,6 +4,7 @@
* Copyright (c) Red Hat <mjg@redhat.com>
* Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@gmail.com>
* Copyright (c) 2014 Pali Rohár <pali.rohar@gmail.com>
+ * Copyright (c) 2017 Dell Inc.
*
* Based on documentation in the libsmbios package:
* Copyright (C) 2005-2014 Dell Inc.
@@ -18,14 +19,14 @@

struct notifier_block;

-/* This structure will be modified by the firmware when we enter
- * system management mode, hence the volatiles */
-
struct calling_interface_buffer {
u16 class;
u16 select;
- volatile u32 input[4];
- volatile u32 output[4];
+ u32 input[4];
+ u32 output[4];
+ u32 argattrib;
+ u32 blength;
+ u8 data[4052];
} __packed;

struct calling_interface_token {
--
2.14.1
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