drivers/char/tpm/tpm_ppi.c - kernel/msm-4.19 - Gitiles

 #include <linux/acpi.h>
 #include "tpm.h"

 static const u8 tpm_ppi_uuid[] = {
 	0xA6, 0xFA, 0xDD, 0x3D,
 	0x1B, 0x36,
 	0xB4, 0x4E,
 	0xA4, 0x24,
 	0x8D, 0x10, 0x08, 0x9D, 0x16, 0x53
 };
 static char *tpm_device_name = "TPM";

 #define TPM_PPI_REVISION_ID	1
 #define TPM_PPI_FN_VERSION	1
 #define TPM_PPI_FN_SUBREQ	2
 #define TPM_PPI_FN_GETREQ	3
 #define TPM_PPI_FN_GETACT	4
 #define TPM_PPI_FN_GETRSP	5
 #define TPM_PPI_FN_SUBREQ2	7
 #define TPM_PPI_FN_GETOPR	8
 #define PPI_TPM_REQ_MAX		22
 #define PPI_VS_REQ_START	128
 #define PPI_VS_REQ_END		255
 #define PPI_VERSION_LEN		3

 static acpi_status ppi_callback(acpi_handle handle, u32 level, void *context,
 				void **return_value)
 {
 	acpi_status status;
 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 	status = acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
 	if (strstr(buffer.pointer, context) != NULL) {
 		*return_value = handle;
 		kfree(buffer.pointer);
 		return AE_CTRL_TERMINATE;
 	}
 	return AE_OK;
 }

 static inline void ppi_assign_params(union acpi_object params[4],
 				     u64 function_num)
 {
 	params[0].type = ACPI_TYPE_BUFFER;
 	params[0].buffer.length = sizeof(tpm_ppi_uuid);
 	params[0].buffer.pointer = (char *)tpm_ppi_uuid;
 	params[1].type = ACPI_TYPE_INTEGER;
 	params[1].integer.value = TPM_PPI_REVISION_ID;
 	params[2].type = ACPI_TYPE_INTEGER;
 	params[2].integer.value = function_num;
 	params[3].type = ACPI_TYPE_PACKAGE;
 	params[3].package.count = 0;
 	params[3].package.elements = NULL;
 }

 static ssize_t tpm_show_ppi_version(struct device *dev,
 				    struct device_attribute *attr, char *buf)
 {
 	acpi_handle handle;
 	acpi_status status;
 	struct acpi_object_list input;
 	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
 	union acpi_object params[4];
 	union acpi_object *obj;

 	input.count = 4;
 	ppi_assign_params(params, TPM_PPI_FN_VERSION);
 	input.pointer = params;
 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 				     ACPI_UINT32_MAX, ppi_callback, NULL,
 				     tpm_device_name, &handle);
 	if (ACPI_FAILURE(status))
 		return -ENXIO;

 	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
 					 ACPI_TYPE_STRING);
 	if (ACPI_FAILURE(status))
 		return -ENOMEM;
 	obj = (union acpi_object *)output.pointer;
 	status = scnprintf(buf, PAGE_SIZE, "%s\n", obj->string.pointer);
 	kfree(output.pointer);
 	return status;
 }

 static ssize_t tpm_show_ppi_request(struct device *dev,
 				    struct device_attribute *attr, char *buf)
 {
 	acpi_handle handle;
 	acpi_status status;
 	struct acpi_object_list input;
 	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
 	union acpi_object params[4];
 	union acpi_object *ret_obj;

 	input.count = 4;
 	ppi_assign_params(params, TPM_PPI_FN_GETREQ);
 	input.pointer = params;
 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 				     ACPI_UINT32_MAX, ppi_callback, NULL,
 				     tpm_device_name, &handle);
 	if (ACPI_FAILURE(status))
 		return -ENXIO;

 	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
 					    ACPI_TYPE_PACKAGE);
 	if (ACPI_FAILURE(status))
 		return -ENOMEM;
 	/*
 	 * output.pointer should be of package type, including two integers.
 	 * The first is function return code, 0 means success and 1 means
 	 * error. The second is pending TPM operation requested by the OS, 0
 	 * means none and >0 means operation value.
 	 */
 	ret_obj = ((union acpi_object *)output.pointer)->package.elements;
 	if (ret_obj->type == ACPI_TYPE_INTEGER) {
 		if (ret_obj->integer.value) {
 			status = -EFAULT;
 			goto cleanup;
 		}
 		ret_obj++;
 		if (ret_obj->type == ACPI_TYPE_INTEGER)
 			status = scnprintf(buf, PAGE_SIZE, "%llu\n",
 					   ret_obj->integer.value);
 		else
 			status = -EINVAL;
 	} else {
 		status = -EINVAL;
 	}
 cleanup:
 	kfree(output.pointer);
 	return status;
 }

 static ssize_t tpm_store_ppi_request(struct device *dev,
 				     struct device_attribute *attr,
 				     const char *buf, size_t count)
 {
 	char version[PPI_VERSION_LEN + 1];
 	acpi_handle handle;
 	acpi_status status;
 	struct acpi_object_list input;
 	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
 	union acpi_object params[4];
 	union acpi_object obj;
 	u32 req;
 	u64 ret;

 	input.count = 4;
 	ppi_assign_params(params, TPM_PPI_FN_VERSION);
 	input.pointer = params;
 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 				     ACPI_UINT32_MAX, ppi_callback, NULL,
 				     tpm_device_name, &handle);
 	if (ACPI_FAILURE(status))
 		return -ENXIO;

 	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
 					    ACPI_TYPE_STRING);
 	if (ACPI_FAILURE(status))
 		return -ENOMEM;
 	strlcpy(version,
 		((union acpi_object *)output.pointer)->string.pointer,
 		PPI_VERSION_LEN + 1);
 	kfree(output.pointer);
 	output.length = ACPI_ALLOCATE_BUFFER;
 	output.pointer = NULL;
 	/*
 	 * the function to submit TPM operation request to pre-os environment
 	 * is updated with function index from SUBREQ to SUBREQ2 since PPI
 	 * version 1.1
 	 */
 	if (strcmp(version, "1.1") == -1)
 		params[2].integer.value = TPM_PPI_FN_SUBREQ;
 	else
 		params[2].integer.value = TPM_PPI_FN_SUBREQ2;
 	/*
 	 * PPI spec defines params[3].type as ACPI_TYPE_PACKAGE. Some BIOS
 	 * accept buffer/string/integer type, but some BIOS accept buffer/
 	 * string/package type. For PPI version 1.0 and 1.1, use buffer type
 	 * for compatibility, and use package type since 1.2 according to spec.
 	 */
 	if (strcmp(version, "1.2") == -1) {
 		params[3].type = ACPI_TYPE_BUFFER;
 		params[3].buffer.length = sizeof(req);
 		sscanf(buf, "%d", &req);
 		params[3].buffer.pointer = (char *)&req;
 	} else {
 		params[3].package.count = 1;
 		obj.type = ACPI_TYPE_INTEGER;
 		sscanf(buf, "%llu", &obj.integer.value);
 		params[3].package.elements = &obj;
 	}

 	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
 					    ACPI_TYPE_INTEGER);
 	if (ACPI_FAILURE(status))
 		return -ENOMEM;
 	ret = ((union acpi_object *)output.pointer)->integer.value;
 	if (ret == 0)
 		status = (acpi_status)count;
 	else if (ret == 1)
 		status = -EPERM;
 	else
 		status = -EFAULT;
 	kfree(output.pointer);
 	return status;
 }

 static ssize_t tpm_show_ppi_transition_action(struct device *dev,
 					      struct device_attribute *attr,
 					      char *buf)
 {
 	char version[PPI_VERSION_LEN + 1];
 	acpi_handle handle;
 	acpi_status status;
 	struct acpi_object_list input;
 	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
 	union acpi_object params[4];
 	u32 ret;
 	char *info[] = {
 		"None",
 		"Shutdown",
 		"Reboot",
 		"OS Vendor-specific",
 		"Error",
 	};
 	input.count = 4;
 	ppi_assign_params(params, TPM_PPI_FN_VERSION);
 	input.pointer = params;
 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 				     ACPI_UINT32_MAX, ppi_callback, NULL,
 				     tpm_device_name, &handle);
 	if (ACPI_FAILURE(status))
 		return -ENXIO;

 	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
 					    ACPI_TYPE_STRING);
 	if (ACPI_FAILURE(status))
 		return -ENOMEM;
 	strlcpy(version,
 		((union acpi_object *)output.pointer)->string.pointer,
 		PPI_VERSION_LEN + 1);
 	/*
 	 * PPI spec defines params[3].type as empty package, but some platforms
 	 * (e.g. Capella with PPI 1.0) need integer/string/buffer type, so for
 	 * compatibility, define params[3].type as buffer, if PPI version < 1.2
 	 */
 	if (strcmp(version, "1.2") == -1) {
 		params[3].type = ACPI_TYPE_BUFFER;
 		params[3].buffer.length =  0;
 		params[3].buffer.pointer = NULL;
 	}
 	params[2].integer.value = TPM_PPI_FN_GETACT;
 	kfree(output.pointer);
 	output.length = ACPI_ALLOCATE_BUFFER;
 	output.pointer = NULL;
 	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
 					    ACPI_TYPE_INTEGER);
 	if (ACPI_FAILURE(status))
 		return -ENOMEM;
 	ret = ((union acpi_object *)output.pointer)->integer.value;
 	if (ret < ARRAY_SIZE(info) - 1)
 		status = scnprintf(buf, PAGE_SIZE, "%d: %s\n", ret, info[ret]);
 	else
 		status = scnprintf(buf, PAGE_SIZE, "%d: %s\n", ret,
 				   info[ARRAY_SIZE(info)-1]);
 	kfree(output.pointer);
 	return status;
 }

 static ssize_t tpm_show_ppi_response(struct device *dev,
 				     struct device_attribute *attr,
 				     char *buf)
 {
 	acpi_handle handle;
 	acpi_status status;
 	struct acpi_object_list input;
 	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
 	union acpi_object params[4];
 	union acpi_object *ret_obj;
 	u64 req;

 	input.count = 4;
 	ppi_assign_params(params, TPM_PPI_FN_GETRSP);
 	input.pointer = params;
 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 				     ACPI_UINT32_MAX, ppi_callback, NULL,
 				     tpm_device_name, &handle);
 	if (ACPI_FAILURE(status))
 		return -ENXIO;

 	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
 					    ACPI_TYPE_PACKAGE);
 	if (ACPI_FAILURE(status))
 		return -ENOMEM;
 	/*
 	 * parameter output.pointer should be of package type, including
 	 * 3 integers. The first means function return code, the second means
 	 * most recent TPM operation request, and the last means response to
 	 * the most recent TPM operation request. Only if the first is 0, and
 	 * the second integer is not 0, the response makes sense.
 	 */
 	ret_obj = ((union acpi_object *)output.pointer)->package.elements;
 	if (ret_obj->type != ACPI_TYPE_INTEGER) {
 		status = -EINVAL;
 		goto cleanup;
 	}
 	if (ret_obj->integer.value) {
 		status = -EFAULT;
 		goto cleanup;
 	}
 	ret_obj++;
 	if (ret_obj->type != ACPI_TYPE_INTEGER) {
 		status = -EINVAL;
 		goto cleanup;
 	}
 	if (ret_obj->integer.value) {
 		req = ret_obj->integer.value;
 		ret_obj++;
 		if (ret_obj->type != ACPI_TYPE_INTEGER) {
 			status = -EINVAL;
 			goto cleanup;
 		}
 		if (ret_obj->integer.value == 0)
 			status = scnprintf(buf, PAGE_SIZE, "%llu %s\n", req,
 					   "0: Success");
 		else if (ret_obj->integer.value == 0xFFFFFFF0)
 			status = scnprintf(buf, PAGE_SIZE, "%llu %s\n", req,
 					   "0xFFFFFFF0: User Abort");
 		else if (ret_obj->integer.value == 0xFFFFFFF1)
 			status = scnprintf(buf, PAGE_SIZE, "%llu %s\n", req,
 					   "0xFFFFFFF1: BIOS Failure");
 		else if (ret_obj->integer.value >= 1 &&
 			 ret_obj->integer.value <= 0x00000FFF)
 			status = scnprintf(buf, PAGE_SIZE, "%llu %llu: %s\n",
 					   req, ret_obj->integer.value,
 					   "Corresponding TPM error");
 		else
 			status = scnprintf(buf, PAGE_SIZE, "%llu %llu: %s\n",
 					   req, ret_obj->integer.value,
 					   "Error");
 	} else {
 		status = scnprintf(buf, PAGE_SIZE, "%llu: %s\n",
 				   ret_obj->integer.value, "No Recent Request");
 	}
 cleanup:
 	kfree(output.pointer);
 	return status;
 }

 static ssize_t show_ppi_operations(char *buf, u32 start, u32 end)
 {
 	char *str = buf;
 	char version[PPI_VERSION_LEN + 1];
 	acpi_handle handle;
 	acpi_status status;
 	struct acpi_object_list input;
 	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
 	union acpi_object params[4];
 	union acpi_object obj;
 	int i;
 	u32 ret;
 	char *info[] = {
 		"Not implemented",
 		"BIOS only",
 		"Blocked for OS by BIOS",
 		"User required",
 		"User not required",
 	};
 	input.count = 4;
 	ppi_assign_params(params, TPM_PPI_FN_VERSION);
 	input.pointer = params;
 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 				     ACPI_UINT32_MAX, ppi_callback, NULL,
 				     tpm_device_name, &handle);
 	if (ACPI_FAILURE(status))
 		return -ENXIO;

 	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
 					 ACPI_TYPE_STRING);
 	if (ACPI_FAILURE(status))
 		return -ENOMEM;

 	strlcpy(version,
 		((union acpi_object *)output.pointer)->string.pointer,
 		PPI_VERSION_LEN + 1);
 	kfree(output.pointer);
 	output.length = ACPI_ALLOCATE_BUFFER;
 	output.pointer = NULL;
 	if (strcmp(version, "1.2") == -1)
 		return -EPERM;

 	params[2].integer.value = TPM_PPI_FN_GETOPR;
 	params[3].package.count = 1;
 	obj.type = ACPI_TYPE_INTEGER;
 	params[3].package.elements = &obj;
 	for (i = start; i <= end; i++) {
 		obj.integer.value = i;
 		status = acpi_evaluate_object_typed(handle, "_DSM",
 			 &input, &output, ACPI_TYPE_INTEGER);
 		if (ACPI_FAILURE(status))
 			return -ENOMEM;

 		ret = ((union acpi_object *)output.pointer)->integer.value;
 		if (ret > 0 && ret < ARRAY_SIZE(info))
 			str += scnprintf(str, PAGE_SIZE, "%d %d: %s\n",
 					 i, ret, info[ret]);
 		kfree(output.pointer);
 		output.length = ACPI_ALLOCATE_BUFFER;
 		output.pointer = NULL;
 	}
 	return str - buf;
 }

 static ssize_t tpm_show_ppi_tcg_operations(struct device *dev,
 					   struct device_attribute *attr,
 					   char *buf)
 {
 	return show_ppi_operations(buf, 0, PPI_TPM_REQ_MAX);
 }

 static ssize_t tpm_show_ppi_vs_operations(struct device *dev,
 					  struct device_attribute *attr,
 					  char *buf)
 {
 	return show_ppi_operations(buf, PPI_VS_REQ_START, PPI_VS_REQ_END);
 }

 static DEVICE_ATTR(version, S_IRUGO, tpm_show_ppi_version, NULL);
 static DEVICE_ATTR(request, S_IRUGO | S_IWUSR | S_IWGRP,
 		   tpm_show_ppi_request, tpm_store_ppi_request);
 static DEVICE_ATTR(transition_action, S_IRUGO,
 		   tpm_show_ppi_transition_action, NULL);
 static DEVICE_ATTR(response, S_IRUGO, tpm_show_ppi_response, NULL);
 static DEVICE_ATTR(tcg_operations, S_IRUGO, tpm_show_ppi_tcg_operations, NULL);
 static DEVICE_ATTR(vs_operations, S_IRUGO, tpm_show_ppi_vs_operations, NULL);

 static struct attribute *ppi_attrs[] = {
 	&dev_attr_version.attr,
 	&dev_attr_request.attr,
 	&dev_attr_transition_action.attr,
 	&dev_attr_response.attr,
 	&dev_attr_tcg_operations.attr,
 	&dev_attr_vs_operations.attr, NULL,
 };
 static struct attribute_group ppi_attr_grp = {
 	.name = "ppi",
 	.attrs = ppi_attrs
 };

 int tpm_add_ppi(struct kobject *parent)
 {
 	return sysfs_create_group(parent, &ppi_attr_grp);
 }

 void tpm_remove_ppi(struct kobject *parent)
 {
 	sysfs_remove_group(parent, &ppi_attr_grp);
 }
	#include <linux/acpi.h>
	#include "tpm.h"

	static const u8 tpm_ppi_uuid[] = {
	0xA6, 0xFA, 0xDD, 0x3D,
	0x1B, 0x36,
	0xB4, 0x4E,
	0xA4, 0x24,
	0x8D, 0x10, 0x08, 0x9D, 0x16, 0x53
	};
	static char *tpm_device_name = "TPM";

	#define TPM_PPI_REVISION_ID 1
	#define TPM_PPI_FN_VERSION 1
	#define TPM_PPI_FN_SUBREQ 2
	#define TPM_PPI_FN_GETREQ 3
	#define TPM_PPI_FN_GETACT 4
	#define TPM_PPI_FN_GETRSP 5
	#define TPM_PPI_FN_SUBREQ2 7
	#define TPM_PPI_FN_GETOPR 8
	#define PPI_TPM_REQ_MAX 22
	#define PPI_VS_REQ_START 128
	#define PPI_VS_REQ_END 255
	#define PPI_VERSION_LEN 3

	static acpi_status ppi_callback(acpi_handle handle, u32 level, void *context,
	void **return_value)
	{
	acpi_status status;
	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
	status = acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
	if (strstr(buffer.pointer, context) != NULL) {
	*return_value = handle;
	kfree(buffer.pointer);
	return AE_CTRL_TERMINATE;
	}
	return AE_OK;
	}

	static inline void ppi_assign_params(union acpi_object params[4],
	u64 function_num)
	{
	params[0].type = ACPI_TYPE_BUFFER;
	params[0].buffer.length = sizeof(tpm_ppi_uuid);
	params[0].buffer.pointer = (char *)tpm_ppi_uuid;
	params[1].type = ACPI_TYPE_INTEGER;
	params[1].integer.value = TPM_PPI_REVISION_ID;
	params[2].type = ACPI_TYPE_INTEGER;
	params[2].integer.value = function_num;
	params[3].type = ACPI_TYPE_PACKAGE;
	params[3].package.count = 0;
	params[3].package.elements = NULL;
	}

	static ssize_t tpm_show_ppi_version(struct device *dev,
	struct device_attribute attr, char buf)
	{
	acpi_handle handle;
	acpi_status status;
	struct acpi_object_list input;
	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object params[4];
	union acpi_object *obj;

	input.count = 4;
	ppi_assign_params(params, TPM_PPI_FN_VERSION);
	input.pointer = params;
	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
	ACPI_UINT32_MAX, ppi_callback, NULL,
	tpm_device_name, &handle);
	if (ACPI_FAILURE(status))
	return -ENXIO;

	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
	ACPI_TYPE_STRING);
	if (ACPI_FAILURE(status))
	return -ENOMEM;
	obj = (union acpi_object *)output.pointer;
	status = scnprintf(buf, PAGE_SIZE, "%s\n", obj->string.pointer);
	kfree(output.pointer);
	return status;
	}

	static ssize_t tpm_show_ppi_request(struct device *dev,
	struct device_attribute attr, char buf)
	{
	acpi_handle handle;
	acpi_status status;
	struct acpi_object_list input;
	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object params[4];
	union acpi_object *ret_obj;

	input.count = 4;
	ppi_assign_params(params, TPM_PPI_FN_GETREQ);
	input.pointer = params;
	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
	ACPI_UINT32_MAX, ppi_callback, NULL,
	tpm_device_name, &handle);
	if (ACPI_FAILURE(status))
	return -ENXIO;

	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
	ACPI_TYPE_PACKAGE);
	if (ACPI_FAILURE(status))
	return -ENOMEM;
	/*
	* output.pointer should be of package type, including two integers.
	* The first is function return code, 0 means success and 1 means
	* error. The second is pending TPM operation requested by the OS, 0
	* means none and >0 means operation value.
	*/
	ret_obj = ((union acpi_object *)output.pointer)->package.elements;
	if (ret_obj->type == ACPI_TYPE_INTEGER) {
	if (ret_obj->integer.value) {
	status = -EFAULT;
	goto cleanup;
	}
	ret_obj++;
	if (ret_obj->type == ACPI_TYPE_INTEGER)
	status = scnprintf(buf, PAGE_SIZE, "%llu\n",
	ret_obj->integer.value);
	else
	status = -EINVAL;
	} else {
	status = -EINVAL;
	}
	cleanup:
	kfree(output.pointer);
	return status;
	}

	static ssize_t tpm_store_ppi_request(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t count)
	{
	char version[PPI_VERSION_LEN + 1];
	acpi_handle handle;
	acpi_status status;
	struct acpi_object_list input;
	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object params[4];
	union acpi_object obj;
	u32 req;
	u64 ret;

	input.count = 4;
	ppi_assign_params(params, TPM_PPI_FN_VERSION);
	input.pointer = params;
	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
	ACPI_UINT32_MAX, ppi_callback, NULL,
	tpm_device_name, &handle);
	if (ACPI_FAILURE(status))
	return -ENXIO;

	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
	ACPI_TYPE_STRING);
	if (ACPI_FAILURE(status))
	return -ENOMEM;
	strlcpy(version,
	((union acpi_object *)output.pointer)->string.pointer,
	PPI_VERSION_LEN + 1);
	kfree(output.pointer);
	output.length = ACPI_ALLOCATE_BUFFER;
	output.pointer = NULL;
	/*
	* the function to submit TPM operation request to pre-os environment
	* is updated with function index from SUBREQ to SUBREQ2 since PPI
	* version 1.1
	*/
	if (strcmp(version, "1.1") == -1)
	params[2].integer.value = TPM_PPI_FN_SUBREQ;
	else
	params[2].integer.value = TPM_PPI_FN_SUBREQ2;
	/*
	* PPI spec defines params[3].type as ACPI_TYPE_PACKAGE. Some BIOS
	* accept buffer/string/integer type, but some BIOS accept buffer/
	* string/package type. For PPI version 1.0 and 1.1, use buffer type
	* for compatibility, and use package type since 1.2 according to spec.
	*/
	if (strcmp(version, "1.2") == -1) {
	params[3].type = ACPI_TYPE_BUFFER;
	params[3].buffer.length = sizeof(req);
	sscanf(buf, "%d", &req);
	params[3].buffer.pointer = (char *)&req;
	} else {
	params[3].package.count = 1;
	obj.type = ACPI_TYPE_INTEGER;
	sscanf(buf, "%llu", &obj.integer.value);
	params[3].package.elements = &obj;
	}

	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
	ACPI_TYPE_INTEGER);
	if (ACPI_FAILURE(status))
	return -ENOMEM;
	ret = ((union acpi_object *)output.pointer)->integer.value;
	if (ret == 0)
	status = (acpi_status)count;
	else if (ret == 1)
	status = -EPERM;
	else
	status = -EFAULT;
	kfree(output.pointer);
	return status;
	}

	static ssize_t tpm_show_ppi_transition_action(struct device *dev,
	struct device_attribute *attr,
	char *buf)
	{
	char version[PPI_VERSION_LEN + 1];
	acpi_handle handle;
	acpi_status status;
	struct acpi_object_list input;
	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object params[4];
	u32 ret;
	char *info[] = {
	"None",
	"Shutdown",
	"Reboot",
	"OS Vendor-specific",
	"Error",
	};
	input.count = 4;
	ppi_assign_params(params, TPM_PPI_FN_VERSION);
	input.pointer = params;
	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
	ACPI_UINT32_MAX, ppi_callback, NULL,
	tpm_device_name, &handle);
	if (ACPI_FAILURE(status))
	return -ENXIO;

	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
	ACPI_TYPE_STRING);
	if (ACPI_FAILURE(status))
	return -ENOMEM;
	strlcpy(version,
	((union acpi_object *)output.pointer)->string.pointer,
	PPI_VERSION_LEN + 1);
	/*
	* PPI spec defines params[3].type as empty package, but some platforms
	* (e.g. Capella with PPI 1.0) need integer/string/buffer type, so for
	* compatibility, define params[3].type as buffer, if PPI version < 1.2
	*/
	if (strcmp(version, "1.2") == -1) {
	params[3].type = ACPI_TYPE_BUFFER;
	params[3].buffer.length = 0;
	params[3].buffer.pointer = NULL;
	}
	params[2].integer.value = TPM_PPI_FN_GETACT;
	kfree(output.pointer);
	output.length = ACPI_ALLOCATE_BUFFER;
	output.pointer = NULL;
	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
	ACPI_TYPE_INTEGER);
	if (ACPI_FAILURE(status))
	return -ENOMEM;
	ret = ((union acpi_object *)output.pointer)->integer.value;
	if (ret < ARRAY_SIZE(info) - 1)
	status = scnprintf(buf, PAGE_SIZE, "%d: %s\n", ret, info[ret]);
	else
	status = scnprintf(buf, PAGE_SIZE, "%d: %s\n", ret,
	info[ARRAY_SIZE(info)-1]);
	kfree(output.pointer);
	return status;
	}

	static ssize_t tpm_show_ppi_response(struct device *dev,
	struct device_attribute *attr,
	char *buf)
	{
	acpi_handle handle;
	acpi_status status;
	struct acpi_object_list input;
	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object params[4];
	union acpi_object *ret_obj;
	u64 req;

	input.count = 4;
	ppi_assign_params(params, TPM_PPI_FN_GETRSP);
	input.pointer = params;
	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
	ACPI_UINT32_MAX, ppi_callback, NULL,
	tpm_device_name, &handle);
	if (ACPI_FAILURE(status))
	return -ENXIO;

	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
	ACPI_TYPE_PACKAGE);
	if (ACPI_FAILURE(status))
	return -ENOMEM;
	/*
	* parameter output.pointer should be of package type, including
	* 3 integers. The first means function return code, the second means
	* most recent TPM operation request, and the last means response to
	* the most recent TPM operation request. Only if the first is 0, and
	* the second integer is not 0, the response makes sense.
	*/
	ret_obj = ((union acpi_object *)output.pointer)->package.elements;
	if (ret_obj->type != ACPI_TYPE_INTEGER) {
	status = -EINVAL;
	goto cleanup;
	}
	if (ret_obj->integer.value) {
	status = -EFAULT;
	goto cleanup;
	}
	ret_obj++;
	if (ret_obj->type != ACPI_TYPE_INTEGER) {
	status = -EINVAL;
	goto cleanup;
	}
	if (ret_obj->integer.value) {
	req = ret_obj->integer.value;
	ret_obj++;
	if (ret_obj->type != ACPI_TYPE_INTEGER) {
	status = -EINVAL;
	goto cleanup;
	}
	if (ret_obj->integer.value == 0)
	status = scnprintf(buf, PAGE_SIZE, "%llu %s\n", req,
	"0: Success");
	else if (ret_obj->integer.value == 0xFFFFFFF0)
	status = scnprintf(buf, PAGE_SIZE, "%llu %s\n", req,
	"0xFFFFFFF0: User Abort");
	else if (ret_obj->integer.value == 0xFFFFFFF1)
	status = scnprintf(buf, PAGE_SIZE, "%llu %s\n", req,
	"0xFFFFFFF1: BIOS Failure");
	else if (ret_obj->integer.value >= 1 &&
	ret_obj->integer.value <= 0x00000FFF)
	status = scnprintf(buf, PAGE_SIZE, "%llu %llu: %s\n",
	req, ret_obj->integer.value,
	"Corresponding TPM error");
	else
	status = scnprintf(buf, PAGE_SIZE, "%llu %llu: %s\n",
	req, ret_obj->integer.value,
	"Error");
	} else {
	status = scnprintf(buf, PAGE_SIZE, "%llu: %s\n",
	ret_obj->integer.value, "No Recent Request");
	}
	cleanup:
	kfree(output.pointer);
	return status;
	}

	static ssize_t show_ppi_operations(char *buf, u32 start, u32 end)
	{
	char *str = buf;
	char version[PPI_VERSION_LEN + 1];
	acpi_handle handle;
	acpi_status status;
	struct acpi_object_list input;
	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object params[4];
	union acpi_object obj;
	int i;
	u32 ret;
	char *info[] = {
	"Not implemented",
	"BIOS only",
	"Blocked for OS by BIOS",
	"User required",
	"User not required",
	};
	input.count = 4;
	ppi_assign_params(params, TPM_PPI_FN_VERSION);
	input.pointer = params;
	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
	ACPI_UINT32_MAX, ppi_callback, NULL,
	tpm_device_name, &handle);
	if (ACPI_FAILURE(status))
	return -ENXIO;

	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
	ACPI_TYPE_STRING);
	if (ACPI_FAILURE(status))
	return -ENOMEM;

	strlcpy(version,
	((union acpi_object *)output.pointer)->string.pointer,
	PPI_VERSION_LEN + 1);
	kfree(output.pointer);
	output.length = ACPI_ALLOCATE_BUFFER;
	output.pointer = NULL;
	if (strcmp(version, "1.2") == -1)
	return -EPERM;

	params[2].integer.value = TPM_PPI_FN_GETOPR;
	params[3].package.count = 1;
	obj.type = ACPI_TYPE_INTEGER;
	params[3].package.elements = &obj;
	for (i = start; i <= end; i++) {
	obj.integer.value = i;
	status = acpi_evaluate_object_typed(handle, "_DSM",
	&input, &output, ACPI_TYPE_INTEGER);
	if (ACPI_FAILURE(status))
	return -ENOMEM;

	ret = ((union acpi_object *)output.pointer)->integer.value;
	if (ret > 0 && ret < ARRAY_SIZE(info))
	str += scnprintf(str, PAGE_SIZE, "%d %d: %s\n",
	i, ret, info[ret]);
	kfree(output.pointer);
	output.length = ACPI_ALLOCATE_BUFFER;
	output.pointer = NULL;
	}
	return str - buf;
	}

	static ssize_t tpm_show_ppi_tcg_operations(struct device *dev,
	struct device_attribute *attr,
	char *buf)
	{
	return show_ppi_operations(buf, 0, PPI_TPM_REQ_MAX);
	}

	static ssize_t tpm_show_ppi_vs_operations(struct device *dev,
	struct device_attribute *attr,
	char *buf)
	{
	return show_ppi_operations(buf, PPI_VS_REQ_START, PPI_VS_REQ_END);
	}

	static DEVICE_ATTR(version, S_IRUGO, tpm_show_ppi_version, NULL);
	static DEVICE_ATTR(request, S_IRUGO \| S_IWUSR \| S_IWGRP,
	tpm_show_ppi_request, tpm_store_ppi_request);
	static DEVICE_ATTR(transition_action, S_IRUGO,
	tpm_show_ppi_transition_action, NULL);
	static DEVICE_ATTR(response, S_IRUGO, tpm_show_ppi_response, NULL);
	static DEVICE_ATTR(tcg_operations, S_IRUGO, tpm_show_ppi_tcg_operations, NULL);
	static DEVICE_ATTR(vs_operations, S_IRUGO, tpm_show_ppi_vs_operations, NULL);

	static struct attribute *ppi_attrs[] = {
	&dev_attr_version.attr,
	&dev_attr_request.attr,
	&dev_attr_transition_action.attr,
	&dev_attr_response.attr,
	&dev_attr_tcg_operations.attr,
	&dev_attr_vs_operations.attr, NULL,
	};
	static struct attribute_group ppi_attr_grp = {
	.name = "ppi",
	.attrs = ppi_attrs
	};

	int tpm_add_ppi(struct kobject *parent)
	{
	return sysfs_create_group(parent, &ppi_attr_grp);
	}

	void tpm_remove_ppi(struct kobject *parent)
	{
	sysfs_remove_group(parent, &ppi_attr_grp);
	}