On Thursday 21 September 2017 08:57:09 Mario Limonciello wrote: > 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.
In my opinion direct access is safer then using ACPI wrapper for same functionality. Anyway, this change would break support for laptops without ACPI-WMI functionality. IIRC I read in some Dell ACPI-WMI documentation that Dell SMM via ACPI-WMI is not supported on all machines (probably older machines) and it is needed to check some vendor bit in DMI data if Dell SMM ACPI-WMI is really supported. In linux kernel we do not want to remove support for older machines, just because machines with new firmware can use also different new communication method/protocol. > As a result, this change removes the dependency on this driver on the > dcdbas kernel module. > > Signed-off-by: Mario Limonciello <[email protected]> > --- > 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 <[email protected]> > * Copyright (c) 2014 Gabriele Mazzotta <[email protected]> > * Copyright (c) 2014 Pali Rohár <[email protected]> > + * 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 <[email protected]>"); > MODULE_AUTHOR("Gabriele Mazzotta <[email protected]>"); > MODULE_AUTHOR("Pali Rohár <[email protected]>"); > -MODULE_DESCRIPTION("Common functions for kernel modules using Dell SMBIOS"); > +MODULE_AUTHOR("Mario Limonciello <[email protected]>"); > +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 <[email protected]> > * Copyright (c) 2014 Gabriele Mazzotta <[email protected]> > * Copyright (c) 2014 Pali Rohár <[email protected]> > + * 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 { -- Pali Rohár [email protected]
