diff options
Diffstat (limited to 'drivers/platform/x86/intel/wmi/sbl-fw-update.c')
-rw-r--r-- | drivers/platform/x86/intel/wmi/sbl-fw-update.c | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/drivers/platform/x86/intel/wmi/sbl-fw-update.c b/drivers/platform/x86/intel/wmi/sbl-fw-update.c new file mode 100644 index 0000000000..3c86e0108a --- /dev/null +++ b/drivers/platform/x86/intel/wmi/sbl-fw-update.c @@ -0,0 +1,144 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Slim Bootloader(SBL) firmware update signaling driver + * + * Slim Bootloader is a small, open-source, non UEFI compliant, boot firmware + * optimized for running on certain Intel platforms. + * + * SBL exposes an ACPI-WMI device via /sys/bus/wmi/devices/<INTEL_WMI_SBL_GUID>. + * This driver further adds "firmware_update_request" device attribute. + * This attribute normally has a value of 0 and userspace can signal SBL + * to update firmware, on next reboot, by writing a value of 1. + * + * More details of SBL firmware update process is available at: + * https://slimbootloader.github.io/security/firmware-update.html + */ + +#include <linux/acpi.h> +#include <linux/device.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/sysfs.h> +#include <linux/wmi.h> + +#define INTEL_WMI_SBL_GUID "44FADEB1-B204-40F2-8581-394BBDC1B651" + +static int get_fwu_request(struct device *dev, u32 *out) +{ + struct acpi_buffer result = {ACPI_ALLOCATE_BUFFER, NULL}; + union acpi_object *obj; + acpi_status status; + + status = wmi_query_block(INTEL_WMI_SBL_GUID, 0, &result); + if (ACPI_FAILURE(status)) { + dev_err(dev, "wmi_query_block failed\n"); + return -ENODEV; + } + + obj = (union acpi_object *)result.pointer; + if (!obj || obj->type != ACPI_TYPE_INTEGER) { + dev_warn(dev, "wmi_query_block returned invalid value\n"); + kfree(obj); + return -EINVAL; + } + + *out = obj->integer.value; + kfree(obj); + + return 0; +} + +static int set_fwu_request(struct device *dev, u32 in) +{ + struct acpi_buffer input; + acpi_status status; + u32 value; + + value = in; + input.length = sizeof(u32); + input.pointer = &value; + + status = wmi_set_block(INTEL_WMI_SBL_GUID, 0, &input); + if (ACPI_FAILURE(status)) { + dev_err(dev, "wmi_set_block failed\n"); + return -ENODEV; + } + + return 0; +} + +static ssize_t firmware_update_request_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + u32 val; + int ret; + + ret = get_fwu_request(dev, &val); + if (ret) + return ret; + + return sprintf(buf, "%d\n", val); +} + +static ssize_t firmware_update_request_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + unsigned int val; + int ret; + + ret = kstrtouint(buf, 0, &val); + if (ret) + return ret; + + /* May later be extended to support values other than 0 and 1 */ + if (val > 1) + return -ERANGE; + + ret = set_fwu_request(dev, val); + if (ret) + return ret; + + return count; +} +static DEVICE_ATTR_RW(firmware_update_request); + +static struct attribute *firmware_update_attrs[] = { + &dev_attr_firmware_update_request.attr, + NULL +}; +ATTRIBUTE_GROUPS(firmware_update); + +static int intel_wmi_sbl_fw_update_probe(struct wmi_device *wdev, + const void *context) +{ + dev_info(&wdev->dev, "Slim Bootloader signaling driver attached\n"); + return 0; +} + +static void intel_wmi_sbl_fw_update_remove(struct wmi_device *wdev) +{ + dev_info(&wdev->dev, "Slim Bootloader signaling driver removed\n"); +} + +static const struct wmi_device_id intel_wmi_sbl_id_table[] = { + { .guid_string = INTEL_WMI_SBL_GUID }, + {} +}; +MODULE_DEVICE_TABLE(wmi, intel_wmi_sbl_id_table); + +static struct wmi_driver intel_wmi_sbl_fw_update_driver = { + .driver = { + .name = "intel-wmi-sbl-fw-update", + .dev_groups = firmware_update_groups, + }, + .probe = intel_wmi_sbl_fw_update_probe, + .remove = intel_wmi_sbl_fw_update_remove, + .id_table = intel_wmi_sbl_id_table, +}; +module_wmi_driver(intel_wmi_sbl_fw_update_driver); + +MODULE_AUTHOR("Jithu Joseph <jithu.joseph@intel.com>"); +MODULE_DESCRIPTION("Slim Bootloader firmware update signaling driver"); +MODULE_LICENSE("GPL v2"); |