> -----Original Message----- > From: Pali Rohár [mailto:pali.rohar@xxxxxxxxx] > Sent: Monday, September 25, 2017 12:19 PM > To: Limonciello, Mario <Mario_Limonciello@xxxxxxxx> > Cc: dvhart@xxxxxxxxxxxxx; LKML <linux-kernel@xxxxxxxxxxxxxxx>; platform-driver- > x86@xxxxxxxxxxxxxxx; quasisec@xxxxxxxxxx > Subject: Re: [PATCH 04/12] platform/x86: dell-smbios: Switch to a WMI-ACPI > interface > > 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. I'd like to hear how this is safer. > > 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 mentioned on other email, I'll rework to support both methods and prefer WMI method. > > As a result, this change removes the dependency on this driver on the > > dcdbas kernel module. > > > > Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxxx> > > --- > > 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@xxxxxxxxxx> > > * Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@xxxxxxxxx> > > * Copyright (c) 2014 Pali Rohár <pali.rohar@xxxxxxxxx> > > + * 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@xxxxxxxxxx>"); > > MODULE_AUTHOR("Gabriele Mazzotta <gabriele.mzt@xxxxxxxxx>"); > > MODULE_AUTHOR("Pali Rohár <pali.rohar@xxxxxxxxx>"); > > -MODULE_DESCRIPTION("Common functions for kernel modules using Dell > SMBIOS"); > > +MODULE_AUTHOR("Mario Limonciello <mario.limonciello@xxxxxxxx>"); > > +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@xxxxxxxxxx> > > * Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@xxxxxxxxx> > > * Copyright (c) 2014 Pali Rohár <pali.rohar@xxxxxxxxx> > > + * 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 > pali.rohar@xxxxxxxxx
