[linux-block.git] / drivers / platform / x86 / intel / wmi / sbl-fw-update.c

// 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)
{
	union acpi_object *obj;

	obj = wmidev_block_query(to_wmi_device(dev), 0);
	if (!obj)
		return -ENODEV;

	if (obj->type != ACPI_TYPE_INTEGER) {
		dev_warn(dev, "wmidev_block_query 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 = wmidev_block_set(to_wmi_device(dev), 0, &input);
	if (ACPI_FAILURE(status)) {
		dev_err(dev, "wmidev_block_set 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");
Commit	Line	Data
2d30fcdd JJ	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* Slim Bootloader(SBL) firmware update signaling driver
	4	*
	5	* Slim Bootloader is a small, open-source, non UEFI compliant, boot firmware
	6	* optimized for running on certain Intel platforms.
	7	*
	8	* SBL exposes an ACPI-WMI device via /sys/bus/wmi/devices/<INTEL_WMI_SBL_GUID>.
	9	* This driver further adds "firmware_update_request" device attribute.
	10	* This attribute normally has a value of 0 and userspace can signal SBL
	11	* to update firmware, on next reboot, by writing a value of 1.
	12	*
	13	* More details of SBL firmware update process is available at:
	14	* https://slimbootloader.github.io/security/firmware-update.html
	15	*/
	16
	17	#include <linux/acpi.h>
	18	#include <linux/device.h>
	19	#include <linux/module.h>
	20	#include <linux/slab.h>
	21	#include <linux/sysfs.h>
	22	#include <linux/wmi.h>
	23
	24	#define INTEL_WMI_SBL_GUID "44FADEB1-B204-40F2-8581-394BBDC1B651"
	25
	26	static int get_fwu_request(struct device dev, u32 out)
	27	{
2d30fcdd	28	union acpi_object *obj;
2d30fcdd	29
75c487fc AW	30	obj = wmidev_block_query(to_wmi_device(dev), 0);
75c487fc AW	31	if (!obj)
2d30fcdd	32	return -ENODEV;
2d30fcdd	33
75c487fc	34	if (obj->type != ACPI_TYPE_INTEGER) {
348d9cc7	35	dev_warn(dev, "wmidev_block_query returned invalid value\n");
2d30fcdd JJ	36	kfree(obj);
	37	return -EINVAL;
	38	}
	39
	40	*out = obj->integer.value;
	41	kfree(obj);
	42
	43	return 0;
	44	}
	45
	46	static int set_fwu_request(struct device *dev, u32 in)
	47	{
	48	struct acpi_buffer input;
	49	acpi_status status;
	50	u32 value;
	51
	52	value = in;
	53	input.length = sizeof(u32);
	54	input.pointer = &value;
	55
75c487fc	56	status = wmidev_block_set(to_wmi_device(dev), 0, &input);
2d30fcdd	57	if (ACPI_FAILURE(status)) {
348d9cc7	58	dev_err(dev, "wmidev_block_set failed\n");
2d30fcdd JJ	59	return -ENODEV;
	60	}
	61
	62	return 0;
	63	}
	64
	65	static ssize_t firmware_update_request_show(struct device *dev,
	66	struct device_attribute *attr,
	67	char *buf)
	68	{
	69	u32 val;
	70	int ret;
	71
	72	ret = get_fwu_request(dev, &val);
	73	if (ret)
	74	return ret;
	75
	76	return sprintf(buf, "%d\n", val);
	77	}
	78
	79	static ssize_t firmware_update_request_store(struct device *dev,
	80	struct device_attribute *attr,
	81	const char *buf, size_t count)
	82	{
	83	unsigned int val;
	84	int ret;
	85
	86	ret = kstrtouint(buf, 0, &val);
	87	if (ret)
	88	return ret;
	89
	90	/* May later be extended to support values other than 0 and 1 */
	91	if (val > 1)
	92	return -ERANGE;
	93
	94	ret = set_fwu_request(dev, val);
	95	if (ret)
	96	return ret;
	97
	98	return count;
	99	}
	100	static DEVICE_ATTR_RW(firmware_update_request);
	101
	102	static struct attribute *firmware_update_attrs[] = {
	103	&dev_attr_firmware_update_request.attr,
	104	NULL
	105	};
	106	ATTRIBUTE_GROUPS(firmware_update);
	107
	108	static int intel_wmi_sbl_fw_update_probe(struct wmi_device *wdev,
	109	const void *context)
	110	{
	111	dev_info(&wdev->dev, "Slim Bootloader signaling driver attached\n");
	112	return 0;
	113	}
	114
2b329f56	115	static void intel_wmi_sbl_fw_update_remove(struct wmi_device *wdev)
2d30fcdd JJ	116	{
2d30fcdd JJ	117	dev_info(&wdev->dev, "Slim Bootloader signaling driver removed\n");
2d30fcdd JJ	118	}
	119
	120	static const struct wmi_device_id intel_wmi_sbl_id_table[] = {
	121	{ .guid_string = INTEL_WMI_SBL_GUID },
	122	{}
	123	};
	124	MODULE_DEVICE_TABLE(wmi, intel_wmi_sbl_id_table);
	125
	126	static struct wmi_driver intel_wmi_sbl_fw_update_driver = {
	127	.driver = {
	128	.name = "intel-wmi-sbl-fw-update",
	129	.dev_groups = firmware_update_groups,
	130	},
	131	.probe = intel_wmi_sbl_fw_update_probe,
	132	.remove = intel_wmi_sbl_fw_update_remove,
	133	.id_table = intel_wmi_sbl_id_table,
	134	};
	135	module_wmi_driver(intel_wmi_sbl_fw_update_driver);
	136
	137	MODULE_AUTHOR("Jithu Joseph <jithu.joseph@intel.com>");
	138	MODULE_DESCRIPTION("Slim Bootloader firmware update signaling driver");
	139	MODULE_LICENSE("GPL v2");