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Subject[PATCH v2 08/14] platform/x86: dell-smbios: Introduce 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.

Now add a WMI-ACPI interface that is detected by WMI probe and preferred
over the SMI interface.

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. It's now an optional compilation option.

Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
---
drivers/platform/x86/Kconfig | 8 +-
drivers/platform/x86/dell-smbios.c | 150 ++++++++++++++++++++++++++++++-------
drivers/platform/x86/dell-smbios.h | 15 +++-
3 files changed, 140 insertions(+), 33 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 579be67de2a3..1fbc40791a48 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.
@@ -19,9 +20,15 @@
#include <linux/dmi.h>
#include <linux/err.h>
#include <linux/mutex.h>
-#include "../../firmware/dcdbas.h"
+#include <linux/wmi.h>
#include "dell-smbios.h"

+#ifdef CONFIG_DCDBAS
+#include "../../firmware/dcdbas.h"
+#endif
+
+#define DELL_WMI_SMBIOS_GUID "A80593CE-A997-11DA-B012-B622A1EF5492"
+
struct calling_interface_structure {
struct dmi_header header;
u16 cmdIOAddress;
@@ -30,12 +37,14 @@ struct calling_interface_structure {
struct calling_interface_token tokens[];
} __packed;

-static struct calling_interface_buffer *buffer;
+static struct calling_interface_buffer *smi_buffer;
+static struct wmi_calling_interface_buffer *wmi_buffer;
static DEFINE_MUTEX(buffer_mutex);

static int da_command_address;
static int da_command_code;
static int da_num_tokens;
+static int has_wmi;
static struct calling_interface_token *da_tokens;

int dell_smbios_error(int value)
@@ -57,13 +66,20 @@ struct calling_interface_buffer *dell_smbios_get_buffer(void)
{
mutex_lock(&buffer_mutex);
dell_smbios_clear_buffer();
- return buffer;
+ if (has_wmi)
+ return &wmi_buffer->smi;
+ return smi_buffer;
}
EXPORT_SYMBOL_GPL(dell_smbios_get_buffer);

void dell_smbios_clear_buffer(void)
{
- memset(buffer, 0, sizeof(struct calling_interface_buffer));
+ if (has_wmi)
+ memset(wmi_buffer, 0,
+ sizeof(struct wmi_calling_interface_buffer));
+ else
+ memset(smi_buffer, 0,
+ sizeof(struct calling_interface_buffer));
}
EXPORT_SYMBOL_GPL(dell_smbios_clear_buffer);

@@ -73,20 +89,60 @@ 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 wmi_calling_interface_buffer *buf)
{
- 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 wmi_calling_interface_buffer);
+ input.pointer = buf;
+
+ 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",
+ buf->smi.class, buf->smi.select,
+ buf->smi.input[0], buf->smi.input[1],
+ buf->smi.input[2], buf->smi.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(buf, 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;
+}

- buffer->class = class;
- buffer->select = select;
+void dell_smbios_send_request(int class, int select)
+{
+ if (has_wmi) {
+ wmi_buffer->smi.class = class;
+ wmi_buffer->smi.select = select;
+ run_wmi_smbios_call(wmi_buffer);
+ }

- dcdbas_smi_request(&command);
+#ifdef CONFIG_DCDBAS
+ else {
+ if (!smi_buffer)
+ return;
+ struct smi_cmd command;
+
+ smi_buffer->class = class;
+ smi_buffer->select = select;
+ command.magic = SMI_CMD_MAGIC;
+ command.command_address = da_command_address;
+ command.command_code = da_command_code;
+ command.ebx = virt_to_phys(smi_buffer);
+ command.ecx = 0x42534931;
+
+ dcdbas_smi_request(&command);
+ }
+#endif
}
EXPORT_SYMBOL_GPL(dell_smbios_send_request);

@@ -167,10 +223,45 @@ static void __init find_tokens(const struct dmi_header *dm, void *dummy)
}
}

-static int __init dell_smbios_init(void)
+static int dell_smbios_wmi_probe(struct wmi_device *wdev)
{
- int ret;
+ /* WMI buffer should be 32k */
+ wmi_buffer = (void *)__get_free_pages(GFP_KERNEL, 3);
+ if (!wmi_buffer)
+ return -ENOMEM;
+
+#ifdef CONFIG_DCDBAS
+ /* no longer need the SMI page */
+ free_page((unsigned long)smi_buffer);
+ smi_buffer = NULL;
+#endif
+
+ has_wmi = 1;
+ return 0;
+}
+
+static int dell_smbios_wmi_remove(struct wmi_device *wdev)
+{
+ free_pages((unsigned long)wmi_buffer, 3);
+ return 0;
+}
+
+static const struct wmi_device_id dell_smbios_wmi_id_table[] = {
+ { .guid_string = DELL_WMI_SMBIOS_GUID },
+ { },
+};

+static struct wmi_driver dell_wmi_smbios_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 dell_smbios_init(void)
+{
dmi_walk(find_tokens, NULL);

if (!da_tokens) {
@@ -178,34 +269,41 @@ static int __init dell_smbios_init(void)
return -ENODEV;
}

+#ifdef CONFIG_DCDBAS
/*
* 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);
- if (!buffer) {
- ret = -ENOMEM;
- goto fail_buffer;
+ smi_buffer = (void *)__get_free_page(GFP_KERNEL | GFP_DMA32);
+#else
+ smi_buffer = NULL;
+#endif
+ wmi_driver_register(&dell_wmi_smbios_driver);
+
+ if (!smi_buffer && !has_wmi) {
+ kfree(da_tokens);
+ return -ENOMEM;
}
-
return 0;
-
-fail_buffer:
- kfree(da_tokens);
- return ret;
}

static void __exit dell_smbios_exit(void)
{
kfree(da_tokens);
- free_page((unsigned long)buffer);
+#ifdef CONFIG_DCDBAS
+ if (!has_wmi)
+ free_page((unsigned long)smi_buffer);
+#endif
+ wmi_driver_unregister(&dell_wmi_smbios_driver);
}

subsys_initcall(dell_smbios_init);
module_exit(dell_smbios_exit);

+
MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
MODULE_AUTHOR("Gabriele Mazzotta <gabriele.mzt@gmail.com>");
MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
+MODULE_AUTHOR("Mario Limonciello <mario.limonciello@dell.com>");
MODULE_DESCRIPTION("Common functions for kernel modules using Dell SMBIOS");
MODULE_LICENSE("GPL");
diff --git a/drivers/platform/x86/dell-smbios.h b/drivers/platform/x86/dell-smbios.h
index 45cbc2292cd3..2f6fce81ee69 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.
@@ -18,9 +19,10 @@

struct notifier_block;

-/* This structure will be modified by the firmware when we enter
- * system management mode, hence the volatiles */
-
+/* If called through fallback SMI rather than WMI 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;
@@ -28,6 +30,13 @@ struct calling_interface_buffer {
volatile u32 output[4];
} __packed;

+struct wmi_calling_interface_buffer {
+ struct calling_interface_buffer smi;
+ u32 argattrib;
+ u32 blength;
+ u8 data[32724];
+} __packed;
+
struct calling_interface_token {
u16 tokenID;
u16 location;
--
2.14.1
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