ACPI: Introduce Platform Firmware Runtime Update device driver

Introduce the pfr_update driver which can be used for Platform Firmware
Runtime code injection and driver update [1].

The user is expected to provide the EFI capsule, and pass it to the
driver by writing the capsule to a device special file. The capsule
is transferred by the driver to the platform firmware with the help
of an ACPI _DSM method under the special ACPI Platform Firmware
Runtime Update device (INTC1080), and the actual firmware update is
carried out by the low-level Management Mode code in the platform
firmware.

This change allows certain pieces of the platform firmware to be
updated on the fly while the system is running (runtime) without the
need to restart it, which is key in the cases when the system needs to
be available 100% of the time and it cannot afford the downtime related
to restarting it, or when the work carried out by the system is
particularly important, so it cannot be interrupted, and it is not
practical to wait until it is complete.

Link: https://uefi.org/sites/default/files/resources/Intel_MM_OS_Interface_Spec_Rev100.pdf # [1]
Tested-by: Hongyu Ning <hongyu.ning@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Documentation/userspace-api/ioctl/ioctl-number.rst

@@ -367,6 +367,7 @@ Code  Seq#    Include File                                           Comments
                                                                      <mailto:aherrman@de.ibm.com>
 0xE5  00-3F  linux/fuse.h
 0xEC  00-01  drivers/platform/chrome/cros_ec_dev.h                   ChromeOS EC driver
+0xEE  00-09  uapi/linux/pfrut.h                                      Platform Firmware Runtime Update and Telemetry
 0xF3  00-3F  drivers/usb/misc/sisusbvga/sisusb.h                     sisfb (in development)
                                                                      <mailto:thomas@winischhofer.net>
 0xF6  all                                                            LTTng Linux Trace Toolkit Next Generation

drivers/acpi/Kconfig

@@ -517,6 +517,24 @@ config ACPI_CONFIGFS
 	  userspace. The configurable ACPI groups will be visible under
 	  /config/acpi, assuming configfs is mounted under /config.
 
+config ACPI_PFRUT
+	tristate "ACPI Platform Firmware Runtime Update and Telemetry"
+	depends on 64BIT
+	help
+	  This mechanism allows certain pieces of the platform firmware
+	  to be updated on the fly while the system is running (runtime)
+	  without the need to restart it, which is key in the cases when
+	  the system needs to be available 100% of the time and it cannot
+	  afford the downtime related to restarting it, or when the work
+	  carried out by the system is particularly important, so it cannot
+	  be interrupted, and it is not practical to wait until it is complete.
+
+	  The existing firmware code can be modified (driver update) or
+	  extended by adding new code to the firmware (code injection).
+
+	  To compile this driver as module, choose M here:
+	  the module will be called pfr_update.
+
 if ARM64
 source "drivers/acpi/arm64/Kconfig"
 

drivers/acpi/Makefile

@@ -102,6 +102,7 @@ obj-$(CONFIG_ACPI_CPPC_LIB)	+= cppc_acpi.o
 obj-$(CONFIG_ACPI_SPCR_TABLE)	+= spcr.o
 obj-$(CONFIG_ACPI_DEBUGGER_USER) += acpi_dbg.o
 obj-$(CONFIG_ACPI_PPTT) 	+= pptt.o
+obj-$(CONFIG_ACPI_PFRUT)	+= pfr_update.o
 
 # processor has its own "processor." module_param namespace
 processor-y			:= processor_driver.o

drivers/acpi/pfr_update.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ACPI Platform Firmware Runtime Update Device driver
+ *
+ * Copyright (C) 2021 Intel Corporation
+ * Author: Chen Yu <yu.c.chen@intel.com>
+ *
+ * pfr_update driver is used for Platform Firmware Runtime
+ * Update, which includes the code injection and driver update.
+ */
+#include <linux/acpi.h>
+#include <linux/device.h>
+#include <linux/efi.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/idr.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/string.h>
+#include <linux/uaccess.h>
+#include <linux/uio.h>
+#include <linux/uuid.h>
+
+#include <uapi/linux/pfrut.h>
+
+#define PFRU_FUNC_STANDARD_QUERY	0
+#define PFRU_FUNC_QUERY_UPDATE_CAP	1
+#define PFRU_FUNC_QUERY_BUF		2
+#define PFRU_FUNC_START		3
+
+#define PFRU_CODE_INJECT_TYPE	1
+#define PFRU_DRIVER_UPDATE_TYPE	2
+
+#define PFRU_REVID_1		1
+#define PFRU_REVID_2		2
+#define PFRU_DEFAULT_REV_ID	PFRU_REVID_1
+
+enum cap_index {
+	CAP_STATUS_IDX = 0,
+	CAP_UPDATE_IDX = 1,
+	CAP_CODE_TYPE_IDX = 2,
+	CAP_FW_VER_IDX = 3,
+	CAP_CODE_RT_VER_IDX = 4,
+	CAP_DRV_TYPE_IDX = 5,
+	CAP_DRV_RT_VER_IDX = 6,
+	CAP_DRV_SVN_IDX = 7,
+	CAP_PLAT_ID_IDX = 8,
+	CAP_OEM_ID_IDX = 9,
+	CAP_OEM_INFO_IDX = 10,
+	CAP_NR_IDX
+};
+
+enum buf_index {
+	BUF_STATUS_IDX = 0,
+	BUF_EXT_STATUS_IDX = 1,
+	BUF_ADDR_LOW_IDX = 2,
+	BUF_ADDR_HI_IDX = 3,
+	BUF_SIZE_IDX = 4,
+	BUF_NR_IDX
+};
+
+enum update_index {
+	UPDATE_STATUS_IDX = 0,
+	UPDATE_EXT_STATUS_IDX = 1,
+	UPDATE_AUTH_TIME_LOW_IDX = 2,
+	UPDATE_AUTH_TIME_HI_IDX = 3,
+	UPDATE_EXEC_TIME_LOW_IDX = 4,
+	UPDATE_EXEC_TIME_HI_IDX = 5,
+	UPDATE_NR_IDX
+};
+
+enum pfru_start_action {
+	START_STAGE = 0,
+	START_ACTIVATE = 1,
+	START_STAGE_ACTIVATE = 2,
+};
+
+struct pfru_device {
+	u32 rev_id, index;
+	struct device *parent_dev;
+	struct miscdevice miscdev;
+};
+
+static DEFINE_IDA(pfru_ida);
+
+/*
+ * Manual reference:
+ * https://uefi.org/sites/default/files/resources/Intel_MM_OS_Interface_Spec_Rev100.pdf
+ *
+ * pfru_guid is the parameter for _DSM method
+ */
+static const guid_t pfru_guid =
+	GUID_INIT(0xECF9533B, 0x4A3C, 0x4E89, 0x93, 0x9E, 0xC7, 0x71,
+		  0x12, 0x60, 0x1C, 0x6D);
+
+/* pfru_code_inj_guid is the UUID to identify code injection EFI capsule file */
+static const guid_t pfru_code_inj_guid =
+	GUID_INIT(0xB2F84B79, 0x7B6E, 0x4E45, 0x88, 0x5F, 0x3F, 0xB9,
+		  0xBB, 0x18, 0x54, 0x02);
+
+/* pfru_drv_update_guid is the UUID to identify driver update EFI capsule file */
+static const guid_t pfru_drv_update_guid =
+	GUID_INIT(0x4569DD8C, 0x75F1, 0x429A, 0xA3, 0xD6, 0x24, 0xDE,
+		  0x80, 0x97, 0xA0, 0xDF);
+
+static inline int pfru_valid_revid(u32 id)
+{
+	return id == PFRU_REVID_1 || id == PFRU_REVID_2;
+}
+
+static inline struct pfru_device *to_pfru_dev(struct file *file)
+{
+	return container_of(file->private_data, struct pfru_device, miscdev);
+}
+
+static int query_capability(struct pfru_update_cap_info *cap_hdr,
+			    struct pfru_device *pfru_dev)
+{
+	acpi_handle handle = ACPI_HANDLE(pfru_dev->parent_dev);
+	union acpi_object *out_obj;
+	int ret = -EINVAL;
+
+	out_obj = acpi_evaluate_dsm_typed(handle, &pfru_guid,
+					  pfru_dev->rev_id,
+					  PFRU_FUNC_QUERY_UPDATE_CAP,
+					  NULL, ACPI_TYPE_PACKAGE);
+	if (!out_obj)
+		return ret;
+
+	if (out_obj->package.count < CAP_NR_IDX ||
+	    out_obj->package.elements[CAP_STATUS_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[CAP_UPDATE_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[CAP_CODE_TYPE_IDX].type != ACPI_TYPE_BUFFER ||
+	    out_obj->package.elements[CAP_FW_VER_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[CAP_CODE_RT_VER_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[CAP_DRV_TYPE_IDX].type != ACPI_TYPE_BUFFER ||
+	    out_obj->package.elements[CAP_DRV_RT_VER_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[CAP_DRV_SVN_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[CAP_PLAT_ID_IDX].type != ACPI_TYPE_BUFFER ||
+	    out_obj->package.elements[CAP_OEM_ID_IDX].type != ACPI_TYPE_BUFFER ||
+	    out_obj->package.elements[CAP_OEM_INFO_IDX].type != ACPI_TYPE_BUFFER)
+		goto free_acpi_buffer;
+
+	cap_hdr->status = out_obj->package.elements[CAP_STATUS_IDX].integer.value;
+	if (cap_hdr->status != DSM_SUCCEED) {
+		ret = -EBUSY;
+		dev_dbg(pfru_dev->parent_dev, "Error Status:%d\n", cap_hdr->status);
+		goto free_acpi_buffer;
+	}
+
+	cap_hdr->update_cap = out_obj->package.elements[CAP_UPDATE_IDX].integer.value;
+	memcpy(&cap_hdr->code_type,
+	       out_obj->package.elements[CAP_CODE_TYPE_IDX].buffer.pointer,
+	       out_obj->package.elements[CAP_CODE_TYPE_IDX].buffer.length);
+	cap_hdr->fw_version =
+		out_obj->package.elements[CAP_FW_VER_IDX].integer.value;
+	cap_hdr->code_rt_version =
+		out_obj->package.elements[CAP_CODE_RT_VER_IDX].integer.value;
+	memcpy(&cap_hdr->drv_type,
+	       out_obj->package.elements[CAP_DRV_TYPE_IDX].buffer.pointer,
+	       out_obj->package.elements[CAP_DRV_TYPE_IDX].buffer.length);
+	cap_hdr->drv_rt_version =
+		out_obj->package.elements[CAP_DRV_RT_VER_IDX].integer.value;
+	cap_hdr->drv_svn =
+		out_obj->package.elements[CAP_DRV_SVN_IDX].integer.value;
+	memcpy(&cap_hdr->platform_id,
+	       out_obj->package.elements[CAP_PLAT_ID_IDX].buffer.pointer,
+	       out_obj->package.elements[CAP_PLAT_ID_IDX].buffer.length);
+	memcpy(&cap_hdr->oem_id,
+	       out_obj->package.elements[CAP_OEM_ID_IDX].buffer.pointer,
+	       out_obj->package.elements[CAP_OEM_ID_IDX].buffer.length);
+	cap_hdr->oem_info_len =
+		out_obj->package.elements[CAP_OEM_INFO_IDX].buffer.length;
+
+	ret = 0;
+
+free_acpi_buffer:
+	kfree(out_obj);
+
+	return ret;
+}
+
+static int query_buffer(struct pfru_com_buf_info *info,
+			struct pfru_device *pfru_dev)
+{
+	acpi_handle handle = ACPI_HANDLE(pfru_dev->parent_dev);
+	union acpi_object *out_obj;
+	int ret = -EINVAL;
+
+	out_obj = acpi_evaluate_dsm_typed(handle, &pfru_guid,
+					  pfru_dev->rev_id, PFRU_FUNC_QUERY_BUF,
+					  NULL, ACPI_TYPE_PACKAGE);
+	if (!out_obj)
+		return ret;
+
+	if (out_obj->package.count < BUF_NR_IDX ||
+	    out_obj->package.elements[BUF_STATUS_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[BUF_EXT_STATUS_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[BUF_ADDR_LOW_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[BUF_ADDR_HI_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[BUF_SIZE_IDX].type != ACPI_TYPE_INTEGER)
+		goto free_acpi_buffer;
+
+	info->status = out_obj->package.elements[BUF_STATUS_IDX].integer.value;
+	info->ext_status =
+		out_obj->package.elements[BUF_EXT_STATUS_IDX].integer.value;
+	if (info->status != DSM_SUCCEED) {
+		ret = -EBUSY;
+		dev_dbg(pfru_dev->parent_dev, "Error Status:%d\n", info->status);
+		dev_dbg(pfru_dev->parent_dev, "Error Extended Status:%d\n", info->ext_status);
+
+		goto free_acpi_buffer;
+	}
+
+	info->addr_lo =
+		out_obj->package.elements[BUF_ADDR_LOW_IDX].integer.value;
+	info->addr_hi =
+		out_obj->package.elements[BUF_ADDR_HI_IDX].integer.value;
+	info->buf_size = out_obj->package.elements[BUF_SIZE_IDX].integer.value;
+
+	ret = 0;
+
+free_acpi_buffer:
+	kfree(out_obj);
+
+	return ret;
+}
+
+static int get_image_type(const struct efi_manage_capsule_image_header *img_hdr,
+			  struct pfru_device *pfru_dev)
+{
+	const efi_guid_t *image_type_id = &img_hdr->image_type_id;
+
+	/* check whether this is a code injection or driver update */
+	if (guid_equal(image_type_id, &pfru_code_inj_guid))
+		return PFRU_CODE_INJECT_TYPE;
+
+	if (guid_equal(image_type_id, &pfru_drv_update_guid))
+		return PFRU_DRIVER_UPDATE_TYPE;
+
+	return -EINVAL;
+}
+
+static int adjust_efi_size(const struct efi_manage_capsule_image_header *img_hdr,
+			   int size)
+{
+	/*
+	 * The (u64 hw_ins) was introduced in UEFI spec version 2,
+	 * and (u64 capsule_support) was introduced in version 3.
+	 * The size needs to be adjusted accordingly. That is to
+	 * say, version 1 should subtract the size of hw_ins+capsule_support,
+	 * and version 2 should sbstract the size of capsule_support.
+	 */
+	size += sizeof(struct efi_manage_capsule_image_header);
+	switch (img_hdr->ver) {
+	case 1:
+		return size - 2 * sizeof(u64);
+
+	case 2:
+		return size - sizeof(u64);
+
+	default:
+		/* only support version 1 and 2 */
+		return -EINVAL;
+	}
+}
+
+static bool applicable_image(const void *data, struct pfru_update_cap_info *cap,
+			     struct pfru_device *pfru_dev)
+{
+	struct pfru_payload_hdr *payload_hdr;
+	const efi_capsule_header_t *cap_hdr = data;
+	const struct efi_manage_capsule_header *m_hdr;
+	const struct efi_manage_capsule_image_header *m_img_hdr;
+	const struct efi_image_auth *auth;
+	int type, size;
+
+	/*
+	 * If the code in the capsule is older than the current
+	 * firmware code, the update will be rejected by the firmware,
+	 * so check the version of it upfront without engaging the
+	 * Management Mode update mechanism which may be costly.
+	 */
+	size = cap_hdr->headersize;
+	m_hdr = data + size;
+	/*
+	 * Current data structure size plus variable array indicated
+	 * by number of (emb_drv_cnt + payload_cnt)
+	 */
+	size += offsetof(struct efi_manage_capsule_header, offset_list) +
+		(m_hdr->emb_drv_cnt + m_hdr->payload_cnt) * sizeof(u64);
+	m_img_hdr = data + size;
+
+	type = get_image_type(m_img_hdr, pfru_dev);
+	if (type < 0)
+		return false;
+
+	size = adjust_efi_size(m_img_hdr, size);
+	if (size < 0)
+		return false;
+
+	auth = data + size;
+	size += sizeof(u64) + auth->auth_info.hdr.len;
+	payload_hdr = (struct pfru_payload_hdr *)(data + size);
+
+	/* finally compare the version */
+	if (type == PFRU_CODE_INJECT_TYPE)
+		return payload_hdr->rt_ver >= cap->code_rt_version;
+
+	return payload_hdr->rt_ver >= cap->drv_rt_version;
+}
+
+static void print_update_debug_info(struct pfru_updated_result *result,
+				    struct pfru_device *pfru_dev)
+{
+	dev_dbg(pfru_dev->parent_dev, "Update result:\n");
+	dev_dbg(pfru_dev->parent_dev, "Authentication Time Low:%lld\n",
+		result->low_auth_time);
+	dev_dbg(pfru_dev->parent_dev, "Authentication Time High:%lld\n",
+		result->high_auth_time);
+	dev_dbg(pfru_dev->parent_dev, "Execution Time Low:%lld\n",
+		result->low_exec_time);
+	dev_dbg(pfru_dev->parent_dev, "Execution Time High:%lld\n",
+		result->high_exec_time);
+}
+
+static int start_update(int action, struct pfru_device *pfru_dev)
+{
+	union acpi_object *out_obj, in_obj, in_buf;
+	struct pfru_updated_result update_result;
+	acpi_handle handle;
+	int ret = -EINVAL;
+
+	memset(&in_obj, 0, sizeof(in_obj));
+	memset(&in_buf, 0, sizeof(in_buf));
+	in_obj.type = ACPI_TYPE_PACKAGE;
+	in_obj.package.count = 1;
+	in_obj.package.elements = &in_buf;
+	in_buf.type = ACPI_TYPE_INTEGER;
+	in_buf.integer.value = action;
+
+	handle = ACPI_HANDLE(pfru_dev->parent_dev);
+	out_obj = acpi_evaluate_dsm_typed(handle, &pfru_guid,
+					  pfru_dev->rev_id, PFRU_FUNC_START,
+					  &in_obj, ACPI_TYPE_PACKAGE);
+	if (!out_obj)
+		return ret;
+
+	if (out_obj->package.count < UPDATE_NR_IDX ||
+	    out_obj->package.elements[UPDATE_STATUS_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[UPDATE_EXT_STATUS_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[UPDATE_AUTH_TIME_LOW_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[UPDATE_AUTH_TIME_HI_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[UPDATE_EXEC_TIME_LOW_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[UPDATE_EXEC_TIME_HI_IDX].type != ACPI_TYPE_INTEGER)
+		goto free_acpi_buffer;
+
+	update_result.status =
+		out_obj->package.elements[UPDATE_STATUS_IDX].integer.value;
+	update_result.ext_status =
+		out_obj->package.elements[UPDATE_EXT_STATUS_IDX].integer.value;
+
+	if (update_result.status != DSM_SUCCEED) {
+		ret = -EBUSY;
+		dev_dbg(pfru_dev->parent_dev, "Error Status:%d\n", update_result.status);
+		dev_dbg(pfru_dev->parent_dev, "Error Extended Status:%d\n",
+			update_result.ext_status);
+
+		goto free_acpi_buffer;
+	}
+
+	update_result.low_auth_time =
+		out_obj->package.elements[UPDATE_AUTH_TIME_LOW_IDX].integer.value;
+	update_result.high_auth_time =
+		out_obj->package.elements[UPDATE_AUTH_TIME_HI_IDX].integer.value;
+	update_result.low_exec_time =
+		out_obj->package.elements[UPDATE_EXEC_TIME_LOW_IDX].integer.value;
+	update_result.high_exec_time =
+		out_obj->package.elements[UPDATE_EXEC_TIME_HI_IDX].integer.value;
+
+	print_update_debug_info(&update_result, pfru_dev);
+	ret = 0;
+
+free_acpi_buffer:
+	kfree(out_obj);
+
+	return ret;
+}
+
+static long pfru_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct pfru_update_cap_info cap_hdr;
+	struct pfru_device *pfru_dev = to_pfru_dev(file);
+	void __user *p = (void __user *)arg;
+	u32 rev;
+	int ret;
+
+	switch (cmd) {
+	case PFRU_IOC_QUERY_CAP:
+		ret = query_capability(&cap_hdr, pfru_dev);
+		if (ret)
+			return ret;
+
+		if (copy_to_user(p, &cap_hdr, sizeof(cap_hdr)))
+			return -EFAULT;
+
+		return 0;
+
+	case PFRU_IOC_SET_REV:
+		if (copy_from_user(&rev, p, sizeof(rev)))
+			return -EFAULT;
+
+		if (!pfru_valid_revid(rev))
+			return -EINVAL;
+
+		pfru_dev->rev_id = rev;
+
+		return 0;
+
+	case PFRU_IOC_STAGE:
+		return start_update(START_STAGE, pfru_dev);
+
+	case PFRU_IOC_ACTIVATE:
+		return start_update(START_ACTIVATE, pfru_dev);
+
+	case PFRU_IOC_STAGE_ACTIVATE:
+		return start_update(START_STAGE_ACTIVATE, pfru_dev);
+
+	default:
+		return -ENOTTY;
+	}
+}
+
+static ssize_t pfru_write(struct file *file, const char __user *buf,
+			  size_t len, loff_t *ppos)
+{
+	struct pfru_device *pfru_dev = to_pfru_dev(file);
+	struct pfru_update_cap_info cap;
+	struct pfru_com_buf_info buf_info;
+	phys_addr_t phy_addr;
+	struct iov_iter iter;
+	struct iovec iov;
+	char *buf_ptr;
+	int ret;
+
+	ret = query_buffer(&buf_info, pfru_dev);
+	if (ret)
+		return ret;
+
+	if (len > buf_info.buf_size)
+		return -EINVAL;
+
+	iov.iov_base = (void __user *)buf;
+	iov.iov_len = len;
+	iov_iter_init(&iter, WRITE, &iov, 1, len);
+
+	/* map the communication buffer */
+	phy_addr = (phys_addr_t)((buf_info.addr_hi << 32) | buf_info.addr_lo);
+	buf_ptr = memremap(phy_addr, buf_info.buf_size, MEMREMAP_WB);
+	if (IS_ERR(buf_ptr))
+		return PTR_ERR(buf_ptr);
+
+	if (!copy_from_iter_full(buf_ptr, len, &iter)) {
+		ret = -EINVAL;
+		goto unmap;
+	}
+
+	/* check if the capsule header has a valid version number */
+	ret = query_capability(&cap, pfru_dev);
+	if (ret)
+		goto unmap;
+
+	if (!applicable_image(buf_ptr, &cap, pfru_dev))
+		ret = -EINVAL;
+
+unmap:
+	memunmap(buf_ptr);
+
+	return ret ?: len;
+}
+
+static const struct file_operations acpi_pfru_fops = {
+	.owner		= THIS_MODULE,
+	.write		= pfru_write,
+	.unlocked_ioctl = pfru_ioctl,
+	.llseek		= noop_llseek,
+};
+
+static int acpi_pfru_remove(struct platform_device *pdev)
+{
+	struct pfru_device *pfru_dev = platform_get_drvdata(pdev);
+
+	misc_deregister(&pfru_dev->miscdev);
+
+	return 0;
+}
+
+static void pfru_put_idx(void *data)
+{
+	struct pfru_device *pfru_dev = data;
+
+	ida_free(&pfru_ida, pfru_dev->index);
+}
+
+static int acpi_pfru_probe(struct platform_device *pdev)
+{
+	acpi_handle handle = ACPI_HANDLE(&pdev->dev);
+	struct pfru_device *pfru_dev;
+	int ret;
+
+	if (!acpi_has_method(handle, "_DSM")) {
+		dev_dbg(&pdev->dev, "Missing _DSM\n");
+		return -ENODEV;
+	}
+
+	pfru_dev = devm_kzalloc(&pdev->dev, sizeof(*pfru_dev), GFP_KERNEL);
+	if (!pfru_dev)
+		return -ENOMEM;
+
+	ret = ida_alloc(&pfru_ida, GFP_KERNEL);
+	if (ret < 0)
+		return ret;
+
+	pfru_dev->index = ret;
+	ret = devm_add_action_or_reset(&pdev->dev, pfru_put_idx, pfru_dev);
+	if (ret)
+		return ret;
+
+	pfru_dev->rev_id = PFRU_DEFAULT_REV_ID;
+	pfru_dev->parent_dev = &pdev->dev;
+
+	pfru_dev->miscdev.minor = MISC_DYNAMIC_MINOR;
+	pfru_dev->miscdev.name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
+						"pfru%d", pfru_dev->index);
+	if (!pfru_dev->miscdev.name)
+		return -ENOMEM;
+
+	pfru_dev->miscdev.nodename = devm_kasprintf(&pdev->dev, GFP_KERNEL,
+						    "acpi_pfr_update%d", pfru_dev->index);
+	if (!pfru_dev->miscdev.nodename)
+		return -ENOMEM;
+
+	pfru_dev->miscdev.fops = &acpi_pfru_fops;
+	pfru_dev->miscdev.parent = &pdev->dev;
+
+	ret = misc_register(&pfru_dev->miscdev);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, pfru_dev);
+
+	return 0;
+}
+
+static const struct acpi_device_id acpi_pfru_ids[] = {
+	{"INTC1080"},
+	{}
+};
+MODULE_DEVICE_TABLE(acpi, acpi_pfru_ids);
+
+static struct platform_driver acpi_pfru_driver = {
+	.driver = {
+		.name = "pfr_update",
+		.acpi_match_table = acpi_pfru_ids,
+	},
+	.probe = acpi_pfru_probe,
+	.remove = acpi_pfru_remove,
+};
+module_platform_driver(acpi_pfru_driver);
+
+MODULE_DESCRIPTION("Platform Firmware Runtime Update device driver");
+MODULE_LICENSE("GPL v2");

include/uapi/linux/pfrut.h

+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Platform Firmware Runtime Update header
+ *
+ * Copyright(c) 2021 Intel Corporation. All rights reserved.
+ */
+#ifndef __PFRUT_H__
+#define __PFRUT_H__
+
+#include <linux/ioctl.h>
+#include <linux/types.h>
+
+#define PFRUT_IOCTL_MAGIC 0xEE
+
+/**
+ * PFRU_IOC_SET_REV - _IOW(PFRUT_IOCTL_MAGIC, 0x01, unsigned int)
+ *
+ * Return:
+ * * 0			- success
+ * * -EFAULT		- fail to read the revision id
+ * * -EINVAL		- user provides an invalid revision id
+ *
+ * Set the Revision ID for Platform Firmware Runtime Update.
+ */
+#define PFRU_IOC_SET_REV _IOW(PFRUT_IOCTL_MAGIC, 0x01, unsigned int)
+
+/**
+ * PFRU_IOC_STAGE - _IOW(PFRUT_IOCTL_MAGIC, 0x02, unsigned int)
+ *
+ * Return:
+ * * 0			- success
+ * * -EINVAL		- stage phase returns invalid result
+ *
+ * Stage a capsule image from communication buffer and perform authentication.
+ */
+#define PFRU_IOC_STAGE _IOW(PFRUT_IOCTL_MAGIC, 0x02, unsigned int)
+
+/**
+ * PFRU_IOC_ACTIVATE - _IOW(PFRUT_IOCTL_MAGIC, 0x03, unsigned int)
+ *
+ * Return:
+ * * 0			- success
+ * * -EINVAL		- activate phase returns invalid result
+ *
+ * Activate a previously staged capsule image.
+ */
+#define PFRU_IOC_ACTIVATE _IOW(PFRUT_IOCTL_MAGIC, 0x03, unsigned int)
+
+/**
+ * PFRU_IOC_STAGE_ACTIVATE - _IOW(PFRUT_IOCTL_MAGIC, 0x04, unsigned int)
+ *
+ * Return:
+ * * 0			- success
+ * * -EINVAL		- stage/activate phase returns invalid result.
+ *
+ * Perform both stage and activation action.
+ */
+#define PFRU_IOC_STAGE_ACTIVATE _IOW(PFRUT_IOCTL_MAGIC, 0x04, unsigned int)
+
+/**
+ * PFRU_IOC_QUERY_CAP - _IOR(PFRUT_IOCTL_MAGIC, 0x05,
+ *			     struct pfru_update_cap_info)
+ *
+ * Return:
+ * * 0			- success
+ * * -EINVAL		- query phase returns invalid result
+ * * -EFAULT		- the result fails to be copied to userspace
+ *
+ * Retrieve information on the Platform Firmware Runtime Update capability.
+ * The information is a struct pfru_update_cap_info.
+ */
+#define PFRU_IOC_QUERY_CAP _IOR(PFRUT_IOCTL_MAGIC, 0x05, struct pfru_update_cap_info)
+
+/**
+ * struct pfru_payload_hdr - Capsule file payload header.
+ *
+ * @sig: Signature of this capsule file.
+ * @hdr_version: Revision of this header structure.
+ * @hdr_size: Size of this header, including the OemHeader bytes.
+ * @hw_ver: The supported firmware version.
+ * @rt_ver: Version of the code injection image.
+ * @platform_id: A platform specific GUID to specify the platform what
+ *               this capsule image support.
+ */
+struct pfru_payload_hdr {
+	__u32 sig;
+	__u32 hdr_version;
+	__u32 hdr_size;
+	__u32 hw_ver;
+	__u32 rt_ver;
+	__u8 platform_id[16];
+};
+
+enum pfru_dsm_status {
+	DSM_SUCCEED = 0,
+	DSM_FUNC_NOT_SUPPORT = 1,
+	DSM_INVAL_INPUT = 2,
+	DSM_HARDWARE_ERR = 3,
+	DSM_RETRY_SUGGESTED = 4,
+	DSM_UNKNOWN = 5,
+	DSM_FUNC_SPEC_ERR = 6,
+};
+
+/**
+ * struct pfru_update_cap_info - Runtime update capability information.
+ *
+ * @status: Indicator of whether this query succeed.
+ * @update_cap: Bitmap to indicate whether the feature is supported.
+ * @code_type: A buffer containing an image type GUID.
+ * @fw_version: Platform firmware version.
+ * @code_rt_version: Code injection runtime version for anti-rollback.
+ * @drv_type: A buffer containing an image type GUID.
+ * @drv_rt_version: The version of the driver update runtime code.
+ * @drv_svn: The secure version number(SVN) of the driver update runtime code.
+ * @platform_id: A buffer containing a platform ID GUID.
+ * @oem_id: A buffer containing an OEM ID GUID.
+ * @oem_info_len: Length of the buffer containing the vendor specific information.
+ */
+struct pfru_update_cap_info {
+	__u32 status;
+	__u32 update_cap;
+
+	__u8 code_type[16];
+	__u32 fw_version;
+	__u32 code_rt_version;
+
+	__u8 drv_type[16];
+	__u32 drv_rt_version;
+	__u32 drv_svn;
+
+	__u8 platform_id[16];
+	__u8 oem_id[16];
+
+	__u32 oem_info_len;
+};
+
+/**
+ * struct pfru_com_buf_info - Communication buffer information.
+ *
+ * @status: Indicator of whether this query succeed.
+ * @ext_status: Implementation specific query result.
+ * @addr_lo: Low 32bit physical address of the communication buffer to hold
+ *           a runtime update package.
+ * @addr_hi: High 32bit physical address of the communication buffer to hold
+ *           a runtime update package.
+ * @buf_size: Maximum size in bytes of the communication buffer.
+ */
+struct pfru_com_buf_info {
+	__u32 status;
+	__u32 ext_status;
+	__u64 addr_lo;
+	__u64 addr_hi;
+	__u32 buf_size;
+};
+
+/**
+ * struct pfru_updated_result - Platform firmware runtime update result information.
+ * @status: Indicator of whether this update succeed.
+ * @ext_status: Implementation specific update result.
+ * @low_auth_time: Low 32bit value of image authentication time in nanosecond.
+ * @high_auth_time: High 32bit value of image authentication time in nanosecond.
+ * @low_exec_time: Low 32bit value of image execution time in nanosecond.
+ * @high_exec_time: High 32bit value of image execution time in nanosecond.
+ */
+struct pfru_updated_result {
+	__u32 status;
+	__u32 ext_status;
+	__u64 low_auth_time;
+	__u64 high_auth_time;
+	__u64 low_exec_time;
+	__u64 high_exec_time;
+};
+
+#endif /* __PFRUT_H__ */