drivers/platform/x86/intel/wmi/sbl-fw-update.c

Source file repositories/reference/linux-study-clean/drivers/platform/x86/intel/wmi/sbl-fw-update.c

File Facts

System
Linux kernel
Corpus path
drivers/platform/x86/intel/wmi/sbl-fw-update.c
Extension
.c
Size
3222 bytes
Lines
129
Domain
Driver Families
Bucket
drivers/platform
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// 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/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 wmi_buffer buffer;
	__le32 *result;
	int ret;

	ret = wmidev_query_block(to_wmi_device(dev), 0, &buffer, sizeof(*result));
	if (ret < 0)
		return ret;

	result = buffer.data;
	*out = le32_to_cpu(*result);
	kfree(result);

	return 0;
}

static int set_fwu_request(struct device *dev, u32 in)
{
	__le32 value = cpu_to_le32(in);
	struct wmi_buffer buffer = {
		.length = sizeof(value),
		.data = &value,
	};

	return wmidev_set_block(to_wmi_device(dev), 0, &buffer);
}

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[] = {

Annotation

Implementation Notes