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SubjectRe: [PATCH v9 17/17] tools/wmi: add a sample for dell smbios communication over WMI
Reviewed-by: Edward O'Callaghan <quasisec@google.com>

On Wed, Oct 18, 2017 at 5:22 AM, Mario Limonciello
<mario.limonciello@dell.com> wrote:
> This application uses the character device /dev/wmi/dell-smbios
> to perform SMBIOS communications from userspace.
>
> It offers demonstrations of a few simple tasks:
> - Running a class/select command
> - Querying a token value
> - Activating a token
>
> Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
> ---
> MAINTAINERS | 1 +
> tools/Makefile | 14 +--
> tools/wmi/Makefile | 18 ++++
> tools/wmi/dell-smbios-example.c | 214 ++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 241 insertions(+), 6 deletions(-)
> create mode 100644 tools/wmi/Makefile
> create mode 100644 tools/wmi/dell-smbios-example.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 84afbf8ef7d5..64529a3f6910 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -3997,6 +3997,7 @@ M: Mario Limonciello <mario.limonciello@dell.com>
> L: platform-driver-x86@vger.kernel.org
> S: Maintained
> F: drivers/platform/x86/dell-smbios-wmi.c
> +F: tools/wmi/dell-smbios-example.c
>
> DELL LAPTOP DRIVER
> M: Matthew Garrett <mjg59@srcf.ucam.org>
> diff --git a/tools/Makefile b/tools/Makefile
> index 9dfede37c8ff..9d2fd2606810 100644
> --- a/tools/Makefile
> +++ b/tools/Makefile
> @@ -29,6 +29,7 @@ help:
> @echo ' usb - USB testing tools'
> @echo ' virtio - vhost test module'
> @echo ' vm - misc vm tools'
> + @echo ' wmi - WMI interface examples'
> @echo ' x86_energy_perf_policy - Intel energy policy tool'
> @echo ''
> @echo 'You can do:'
> @@ -57,7 +58,7 @@ acpi: FORCE
> cpupower: FORCE
> $(call descend,power/$@)
>
> -cgroup firewire hv guest spi usb virtio vm net iio gpio objtool leds: FORCE
> +cgroup firewire hv guest spi usb virtio vm net iio gpio objtool leds wmi: FORCE
> $(call descend,$@)
>
> liblockdep: FORCE
> @@ -92,7 +93,7 @@ kvm_stat: FORCE
> all: acpi cgroup cpupower gpio hv firewire liblockdep \
> perf selftests spi turbostat usb \
> virtio vm net x86_energy_perf_policy \
> - tmon freefall iio objtool kvm_stat
> + tmon freefall iio objtool kvm_stat wmi
>
> acpi_install:
> $(call descend,power/$(@:_install=),install)
> @@ -100,7 +101,7 @@ acpi_install:
> cpupower_install:
> $(call descend,power/$(@:_install=),install)
>
> -cgroup_install firewire_install gpio_install hv_install iio_install perf_install spi_install usb_install virtio_install vm_install net_install objtool_install:
> +cgroup_install firewire_install gpio_install hv_install iio_install perf_install spi_install usb_install virtio_install vm_install net_install objtool_install wmi_install:
> $(call descend,$(@:_install=),install)
>
> liblockdep_install:
> @@ -125,7 +126,8 @@ install: acpi_install cgroup_install cpupower_install gpio_install \
> hv_install firewire_install iio_install liblockdep_install \
> perf_install selftests_install turbostat_install usb_install \
> virtio_install vm_install net_install x86_energy_perf_policy_install \
> - tmon_install freefall_install objtool_install kvm_stat_install
> + tmon_install freefall_install objtool_install kvm_stat_install \
> + wmi_install
>
> acpi_clean:
> $(call descend,power/acpi,clean)
> @@ -133,7 +135,7 @@ acpi_clean:
> cpupower_clean:
> $(call descend,power/cpupower,clean)
>
> -cgroup_clean hv_clean firewire_clean spi_clean usb_clean virtio_clean vm_clean net_clean iio_clean gpio_clean objtool_clean leds_clean:
> +cgroup_clean hv_clean firewire_clean spi_clean usb_clean virtio_clean vm_clean wmi_clean net_clean iio_clean gpio_clean objtool_clean leds_clean:
> $(call descend,$(@:_clean=),clean)
>
> liblockdep_clean:
> @@ -171,6 +173,6 @@ clean: acpi_clean cgroup_clean cpupower_clean hv_clean firewire_clean \
> perf_clean selftests_clean turbostat_clean spi_clean usb_clean virtio_clean \
> vm_clean net_clean iio_clean x86_energy_perf_policy_clean tmon_clean \
> freefall_clean build_clean libbpf_clean libsubcmd_clean liblockdep_clean \
> - gpio_clean objtool_clean leds_clean
> + gpio_clean objtool_clean leds_clean wmi_clean
>
> .PHONY: FORCE
> diff --git a/tools/wmi/Makefile b/tools/wmi/Makefile
> new file mode 100644
> index 000000000000..e664f1167388
> --- /dev/null
> +++ b/tools/wmi/Makefile
> @@ -0,0 +1,18 @@
> +PREFIX ?= /usr
> +SBINDIR ?= sbin
> +INSTALL ?= install
> +CFLAGS += -D__EXPORTED_HEADERS__ -I../../include/uapi -I../../include
> +CC = $(CROSS_COMPILE)gcc
> +
> +TARGET = dell-smbios-example
> +
> +all: $(TARGET)
> +
> +%: %.c
> + $(CC) $(CFLAGS) $(LDFLAGS) -o $@ $<
> +
> +clean:
> + $(RM) $(TARGET)
> +
> +install: dell-smbios-example
> + $(INSTALL) -D -m 755 $(TARGET) $(DESTDIR)$(PREFIX)/$(SBINDIR)/$(TARGET)
> diff --git a/tools/wmi/dell-smbios-example.c b/tools/wmi/dell-smbios-example.c
> new file mode 100644
> index 000000000000..69c4dd9c6056
> --- /dev/null
> +++ b/tools/wmi/dell-smbios-example.c
> @@ -0,0 +1,214 @@
> +/*
> + * Sample application for SMBIOS communication over WMI interface
> + * Performs the following:
> + * - Simple class/select lookup for TPM information
> + * - Simple query of known tokens and their values
> + * - Simple activation of a token
> + *
> + * 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.
> + */
> +
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <sys/ioctl.h>
> +#include <unistd.h>
> +
> +/* if uapi header isn't installed, this might not yet exist */
> +#ifndef __packed
> +#define __packed __attribute__((packed))
> +#endif
> +#include <linux/wmi.h>
> +
> +/* It would be better to discover these using udev, but for a simple
> + * application they're hardcoded
> + */
> +static const char *ioctl_devfs = "/dev/wmi/dell-smbios";
> +static const char *token_sysfs =
> + "/sys/bus/platform/devices/dell-smbios.0/tokens";
> +static const char *buffer_sysfs =
> + "/sys/bus/wmi/devices/A80593CE-A997-11DA-B012-B622A1EF5492/required_buffer_size";
> +
> +static void show_buffer(struct dell_wmi_smbios_buffer *buffer)
> +{
> + printf("Call: %x/%x [%x,%x,%x,%x]\nResults: [%8x,%8x,%8x,%8x]\n",
> + buffer->std.class, buffer->std.select,
> + buffer->std.input[0], buffer->std.input[1],
> + buffer->std.input[2], buffer->std.input[3],
> + buffer->std.output[0], buffer->std.output[1],
> + buffer->std.output[2], buffer->std.output[3]);
> +}
> +
> +static int run_wmi_smbios_cmd(struct dell_wmi_smbios_buffer *buffer)
> +{
> + int fd;
> + int ret;
> +
> + fd = open(ioctl_devfs, O_NONBLOCK);
> + ret = ioctl(fd, DELL_WMI_SMBIOS_CMD, buffer);
> + close(fd);
> + return ret;
> +}
> +
> +static int find_token(__u16 token, __u16 *location, __u16 *value)
> +{
> + char location_sysfs[60];
> + char value_sysfs[57];
> + char buf[4096];
> + FILE *f;
> + int ret;
> +
> + ret = sprintf(value_sysfs, "%s/%04x_value", token_sysfs, token);
> + if (ret < 0) {
> + printf("sprintf value failed\n");
> + return 2;
> + }
> + f = fopen(value_sysfs, "rb");
> + if (!f) {
> + printf("failed to open %s\n", value_sysfs);
> + return 2;
> + }
> + fread(buf, 1, 4096, f);
> + fclose(f);
> + *value = (__u16) strtol(buf, NULL, 16);
> +
> + ret = sprintf(location_sysfs, "%s/%04x_location", token_sysfs, token);
> + if (ret < 0) {
> + printf("sprintf location failed\n");
> + return 1;
> + }
> + f = fopen(location_sysfs, "rb");
> + if (!f) {
> + printf("failed to open %s\n", location_sysfs);
> + return 2;
> + }
> + fread(buf, 1, 4096, f);
> + fclose(f);
> + *location = (__u16) strtol(buf, NULL, 16);
> +
> + if (*location)
> + return 0;
> + return 2;
> +}
> +
> +static int token_is_active(__u16 *location, __u16 *cmpvalue,
> + struct dell_wmi_smbios_buffer *buffer)
> +{
> + int ret;
> +
> + buffer->std.class = CLASS_TOKEN_READ;
> + buffer->std.select = SELECT_TOKEN_STD;
> + buffer->std.input[0] = *location;
> + ret = run_wmi_smbios_cmd(buffer);
> + if (ret != 0 || buffer->std.output[0] != 0)
> + return ret;
> + ret = (buffer->std.output[1] == *cmpvalue);
> + return ret;
> +}
> +
> +static int query_token(__u16 token, struct dell_wmi_smbios_buffer *buffer)
> +{
> + __u16 location;
> + __u16 value;
> + int ret;
> +
> + ret = find_token(token, &location, &value);
> + if (ret != 0) {
> + printf("unable to find token %04x\n", token);
> + return 1;
> + }
> + return token_is_active(&location, &value, buffer);
> +}
> +
> +static int activate_token(struct dell_wmi_smbios_buffer *buffer,
> + __u16 token)
> +{
> + __u16 location;
> + __u16 value;
> + int ret;
> +
> + ret = find_token(token, &location, &value);
> + if (ret != 0) {
> + printf("unable to find token %04x\n", token);
> + return 1;
> + }
> + buffer->std.class = CLASS_TOKEN_WRITE;
> + buffer->std.select = SELECT_TOKEN_STD;
> + buffer->std.input[0] = location;
> + buffer->std.input[1] = 1;
> + ret = run_wmi_smbios_cmd(buffer);
> + return ret;
> +}
> +
> +static int query_buffer_size(__u64 *buffer_size)
> +{
> + char buf[4096];
> + FILE *f;
> +
> + f = fopen(buffer_sysfs, "rb");
> + if (!f)
> + return -EINVAL;
> + fread(buf, 1, 4096, f);
> + fclose(f);
> + *buffer_size = strtol(buf, NULL, 10);
> + return EXIT_SUCCESS;
> +}
> +
> +int main(void)
> +{
> + struct dell_wmi_smbios_buffer *buffer;
> + int ret;
> + __u64 value = 0;
> +
> + ret = query_buffer_size(&value);
> + if (ret == EXIT_FAILURE || !value) {
> + printf("Unable to read buffer size\n");
> + goto out;
> + }
> + printf("Detected required buffer size %lld\n", value);
> +
> + buffer = malloc(value);
> + if (buffer == NULL) {
> + printf("failed to alloc memory for ioctl\n");
> + ret = -ENOMEM;
> + goto out;
> + }
> + buffer->length = value;
> +
> + /* simple SMBIOS call for looking up TPM info */
> + buffer->std.class = CLASS_FLASH_INTERFACE;
> + buffer->std.select = SELECT_FLASH_INTERFACE;
> + buffer->std.input[0] = 2;
> + ret = run_wmi_smbios_cmd(buffer);
> + if (ret) {
> + printf("smbios ioctl failed: %d\n", ret);
> + ret = EXIT_FAILURE;
> + goto out;
> + }
> + show_buffer(buffer);
> +
> + /* query some tokens */
> + ret = query_token(CAPSULE_EN_TOKEN, buffer);
> + printf("UEFI Capsule enabled token is: %d\n", ret);
> + ret = query_token(CAPSULE_DIS_TOKEN, buffer);
> + printf("UEFI Capsule disabled token is: %d\n", ret);
> +
> + /* activate UEFI capsule token if disabled */
> + if (ret) {
> + printf("Enabling UEFI capsule token");
> + if (activate_token(buffer, CAPSULE_EN_TOKEN)) {
> + printf("activate failed\n");
> + ret = -1;
> + goto out;
> + }
> + }
> + ret = EXIT_SUCCESS;
> +out:
> + free(buffer);
> + return ret;
> +}
> --
> 2.14.1
>

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