Merge branch 'acpi-dsm'

* acpi-dsm:
  ACPI / extlog: replace open-coded _DSM code with helper functions
  ACPI / nouveau: replace open-coded _DSM code with helper functions
  nouveau / ACPI: fix memory leak in ACPI _DSM related code
  ACPI / i915: replace open-coded _DSM code with helper functions
  ACPI / i2c-hid: replace open-coded _DSM code with helper functions
  ACPI / TPM: detect PPI features by checking availability of _DSM functions
  ACPI / TPM: replace open-coded _DSM code with helper functions
  ACPI / TPM: match node name instead of full path when searching for TPM device
  PCI / pci-label: treat PCI label with index 0 as valid label
  ACPI / PCI: replace open-coded _DSM code with helper functions
  PCI / pci-label: release allocated ACPI object on error recovery path
  ACPI: introduce helper interfaces for _DSM method

9 files changed, 403 insertions, 664 deletions

diff --git a/drivers/acpi/acpi_extlog.c b/drivers/acpi/acpi_extlog.c
index 2635a01..9416668 100644
--- a/drivers/acpi/acpi_extlog.c
+++ b/drivers/acpi/acpi_extlog.c
@@ -19,11 +19,9 @@
 #define EXT_ELOG_ENTRY_MASK	GENMASK_ULL(51, 0) /* elog entry address mask */
 
 #define EXTLOG_DSM_REV		0x0
-#define	EXTLOG_FN_QUERY		0x0
 #define	EXTLOG_FN_ADDR		0x1
 
 #define FLAG_OS_OPTIN		BIT(0)
-#define EXTLOG_QUERY_L1_EXIST	BIT(1)
 #define ELOG_ENTRY_VALID	(1ULL<<63)
 #define ELOG_ENTRY_LEN		0x1000
 
@@ -42,7 +40,7 @@ struct extlog_l1_head {
 	u8  rev1[12];
 };
 
-static u8 extlog_dsm_uuid[] = "663E35AF-CC10-41A4-88EA-5470AF055295";
+static u8 extlog_dsm_uuid[] __initdata = "663E35AF-CC10-41A4-88EA-5470AF055295";
 
 /* L1 table related physical address */
 static u64 elog_base;
@@ -152,62 +150,27 @@ static int extlog_print(struct notifier_block *nb, unsigned long val,
 	return NOTIFY_DONE;
 }
 
-static int extlog_get_dsm(acpi_handle handle, int rev, int func, u64 *ret)
+static bool __init extlog_get_l1addr(void)
 {
-	struct acpi_buffer buf = {ACPI_ALLOCATE_BUFFER, NULL};
-	struct acpi_object_list input;
-	union acpi_object params[4], *obj;
 	u8 uuid[16];
-	int i;
+	acpi_handle handle;
+	union acpi_object *obj;
 
 	acpi_str_to_uuid(extlog_dsm_uuid, uuid);
-	input.count = 4;
-	input.pointer = params;
-	params[0].type = ACPI_TYPE_BUFFER;
-	params[0].buffer.length = 16;
-	params[0].buffer.pointer = uuid;
-	params[1].type = ACPI_TYPE_INTEGER;
-	params[1].integer.value = rev;
-	params[2].type = ACPI_TYPE_INTEGER;
-	params[2].integer.value = func;
-	params[3].type = ACPI_TYPE_PACKAGE;
-	params[3].package.count = 0;
-	params[3].package.elements = NULL;
-
-	if (ACPI_FAILURE(acpi_evaluate_object(handle, "_DSM", &input, &buf)))
-		return -1;
-
-	*ret = 0;
-	obj = (union acpi_object *)buf.pointer;
-	if (obj->type == ACPI_TYPE_INTEGER) {
-		*ret = obj->integer.value;
-	} else if (obj->type == ACPI_TYPE_BUFFER) {
-		if (obj->buffer.length <= 8) {
-			for (i = 0; i < obj->buffer.length; i++)
-				*ret |= (obj->buffer.pointer[i] << (i * 8));
-		}
-	}
-	kfree(buf.pointer);
-
-	return 0;
-}
-
-static bool extlog_get_l1addr(void)
-{
-	acpi_handle handle;
-	u64 ret;
 
 	if (ACPI_FAILURE(acpi_get_handle(NULL, "\\_SB", &handle)))
 		return false;
-
-	if (extlog_get_dsm(handle, EXTLOG_DSM_REV, EXTLOG_FN_QUERY, &ret) ||
-	    !(ret & EXTLOG_QUERY_L1_EXIST))
+	if (!acpi_check_dsm(handle, uuid, EXTLOG_DSM_REV, 1 << EXTLOG_FN_ADDR))
 		return false;
-
-	if (extlog_get_dsm(handle, EXTLOG_DSM_REV, EXTLOG_FN_ADDR, &ret))
+	obj = acpi_evaluate_dsm_typed(handle, uuid, EXTLOG_DSM_REV,
+				      EXTLOG_FN_ADDR, NULL, ACPI_TYPE_INTEGER);
+	if (!obj) {
 		return false;
+	} else {
+		l1_dirbase = obj->integer.value;
+		ACPI_FREE(obj);
+	}
 
-	l1_dirbase = ret;
 	/* Spec says L1 directory must be 4K aligned, bail out if it isn't */
 	if (l1_dirbase & ((1 << 12) - 1)) {
 		pr_warn(FW_BUG "L1 Directory is invalid at physical %llx\n",
diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
index 1336b91..0347a37 100644
--- a/drivers/acpi/utils.c
+++ b/drivers/acpi/utils.c
@@ -572,3 +572,100 @@ acpi_status acpi_evaluate_lck(acpi_handle handle, int lock)
 
 	return status;
 }
+
+/**
+ * acpi_evaluate_dsm - evaluate device's _DSM method
+ * @handle: ACPI device handle
+ * @uuid: UUID of requested functions, should be 16 bytes
+ * @rev: revision number of requested function
+ * @func: requested function number
+ * @argv4: the function specific parameter
+ *
+ * Evaluate device's _DSM method with specified UUID, revision id and
+ * function number. Caller needs to free the returned object.
+ *
+ * Though ACPI defines the fourth parameter for _DSM should be a package,
+ * some old BIOSes do expect a buffer or an integer etc.
+ */
+union acpi_object *
+acpi_evaluate_dsm(acpi_handle handle, const u8 *uuid, int rev, int func,
+		  union acpi_object *argv4)
+{
+	acpi_status ret;
+	struct acpi_buffer buf = {ACPI_ALLOCATE_BUFFER, NULL};
+	union acpi_object params[4];
+	struct acpi_object_list input = {
+		.count = 4,
+		.pointer = params,
+	};
+
+	params[0].type = ACPI_TYPE_BUFFER;
+	params[0].buffer.length = 16;
+	params[0].buffer.pointer = (char *)uuid;
+	params[1].type = ACPI_TYPE_INTEGER;
+	params[1].integer.value = rev;
+	params[2].type = ACPI_TYPE_INTEGER;
+	params[2].integer.value = func;
+	if (argv4) {
+		params[3] = *argv4;
+	} else {
+		params[3].type = ACPI_TYPE_PACKAGE;
+		params[3].package.count = 0;
+		params[3].package.elements = NULL;
+	}
+
+	ret = acpi_evaluate_object(handle, "_DSM", &input, &buf);
+	if (ACPI_SUCCESS(ret))
+		return (union acpi_object *)buf.pointer;
+
+	if (ret != AE_NOT_FOUND)
+		acpi_handle_warn(handle,
+				"failed to evaluate _DSM (0x%x)\n", ret);
+
+	return NULL;
+}
+EXPORT_SYMBOL(acpi_evaluate_dsm);
+
+/**
+ * acpi_check_dsm - check if _DSM method supports requested functions.
+ * @handle: ACPI device handle
+ * @uuid: UUID of requested functions, should be 16 bytes at least
+ * @rev: revision number of requested functions
+ * @funcs: bitmap of requested functions
+ * @exclude: excluding special value, used to support i915 and nouveau
+ *
+ * Evaluate device's _DSM method to check whether it supports requested
+ * functions. Currently only support 64 functions at maximum, should be
+ * enough for now.
+ */
+bool acpi_check_dsm(acpi_handle handle, const u8 *uuid, int rev, u64 funcs)
+{
+	int i;
+	u64 mask = 0;
+	union acpi_object *obj;
+
+	if (funcs == 0)
+		return false;
+
+	obj = acpi_evaluate_dsm(handle, uuid, rev, 0, NULL);
+	if (!obj)
+		return false;
+
+	/* For compatibility, old BIOSes may return an integer */
+	if (obj->type == ACPI_TYPE_INTEGER)
+		mask = obj->integer.value;
+	else if (obj->type == ACPI_TYPE_BUFFER)
+		for (i = 0; i < obj->buffer.length && i < 8; i++)
+			mask |= (((u8)obj->buffer.pointer[i]) << (i * 8));
+	ACPI_FREE(obj);
+
+	/*
+	 * Bit 0 indicates whether there's support for any functions other than
+	 * function 0 for the specified UUID and revision.
+	 */
+	if ((mask & 0x1) && (mask & funcs) == funcs)
+		return true;
+
+	return false;
+}
+EXPORT_SYMBOL(acpi_check_dsm);
diff --git a/drivers/char/tpm/tpm_ppi.c b/drivers/char/tpm/tpm_ppi.c
index 70dbee4..b3ea223 100644
--- a/drivers/char/tpm/tpm_ppi.c
+++ b/drivers/char/tpm/tpm_ppi.c
@@ -1,15 +1,6 @@
 #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
@@ -23,250 +14,178 @@ static char *tpm_device_name = "TPM";
 #define PPI_VS_REQ_END		255
 #define PPI_VERSION_LEN		3
 
+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_ppi_version[PPI_VERSION_LEN + 1];
+static acpi_handle tpm_ppi_handle;
+
 static acpi_status ppi_callback(acpi_handle handle, u32 level, void *context,
 				void **return_value)
 {
-	acpi_status status = AE_OK;
-	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object *obj;
 
-	if (ACPI_SUCCESS(acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer))) {
-		if (strstr(buffer.pointer, context) != NULL) {
-			*return_value = handle;
-			status = AE_CTRL_TERMINATE;
-		}
-		kfree(buffer.pointer);
+	if (!acpi_check_dsm(handle, tpm_ppi_uuid, TPM_PPI_REVISION_ID,
+			    1 << TPM_PPI_FN_VERSION))
+		return AE_OK;
+
+	/* Cache version string */
+	obj = acpi_evaluate_dsm_typed(handle, tpm_ppi_uuid,
+				      TPM_PPI_REVISION_ID, TPM_PPI_FN_VERSION,
+				      NULL, ACPI_TYPE_STRING);
+	if (obj) {
+		strlcpy(tpm_ppi_version, obj->string.pointer,
+			PPI_VERSION_LEN + 1);
+		ACPI_FREE(obj);
 	}
 
-	return status;
+	*return_value = handle;
+
+	return AE_CTRL_TERMINATE;
 }
 
-static inline void ppi_assign_params(union acpi_object params[4],
-				     u64 function_num)
+static inline union acpi_object *
+tpm_eval_dsm(int func, acpi_object_type type, union acpi_object *argv4)
 {
-	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;
+	BUG_ON(!tpm_ppi_handle);
+	return acpi_evaluate_dsm_typed(tpm_ppi_handle, tpm_ppi_uuid,
+				       TPM_PPI_REVISION_ID, func, argv4, type);
 }
 
 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;
+	return scnprintf(buf, PAGE_SIZE, "%s\n", tpm_ppi_version);
 }
 
 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))
+	ssize_t size = -EINVAL;
+	union acpi_object *obj;
+
+	obj = tpm_eval_dsm(TPM_PPI_FN_GETREQ, ACPI_TYPE_PACKAGE, NULL);
+	if (!obj)
 		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);
+	if (obj->package.count == 2 &&
+	    obj->package.elements[0].type == ACPI_TYPE_INTEGER &&
+	    obj->package.elements[1].type == ACPI_TYPE_INTEGER) {
+		if (obj->package.elements[0].integer.value)
+			size = -EFAULT;
 		else
-			status = -EINVAL;
-	} else {
-		status = -EINVAL;
+			size = scnprintf(buf, PAGE_SIZE, "%llu\n",
+				 obj->package.elements[1].integer.value);
 	}
-cleanup:
-	kfree(output.pointer);
-	return status;
+
+	ACPI_FREE(obj);
+
+	return size;
 }
 
 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;
+	int func = TPM_PPI_FN_SUBREQ;
+	union acpi_object *obj, tmp;
+	union acpi_object argv4 = ACPI_INIT_DSM_ARGV4(1, &tmp);
 
-	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;
+	if (acpi_check_dsm(tpm_ppi_handle, tpm_ppi_uuid, TPM_PPI_REVISION_ID,
+			   1 << TPM_PPI_FN_SUBREQ2))
+		func = 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;
+	if (strcmp(tpm_ppi_version, "1.2") < 0) {
+		if (sscanf(buf, "%d", &req) != 1)
+			return -EINVAL;
+		argv4.type = ACPI_TYPE_BUFFER;
+		argv4.buffer.length = sizeof(req);
+		argv4.buffer.pointer = (u8 *)&req;
+	} else {
+		tmp.type = ACPI_TYPE_INTEGER;
+		if (sscanf(buf, "%llu", &tmp.integer.value) != 1)
+			return -EINVAL;
+	}
+
+	obj = tpm_eval_dsm(func, ACPI_TYPE_INTEGER, &argv4);
+	if (!obj) {
+		return -ENXIO;
 	} else {
-		params[3].package.count = 1;
-		obj.type = ACPI_TYPE_INTEGER;
-		sscanf(buf, "%llu", &obj.integer.value);
-		params[3].package.elements = &obj;
+		ret = obj->integer.value;
+		ACPI_FREE(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;
+		return (acpi_status)count;
+
+	return (ret == 1) ? -EPERM : -EFAULT;
 }
 
 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[] = {
+	acpi_status status;
+	union acpi_object *obj = NULL;
+	union acpi_object tmp = {
+		.buffer.type = ACPI_TYPE_BUFFER,
+		.buffer.length = 0,
+		.buffer.pointer = NULL
+	};
+
+	static 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;
+	if (strcmp(tpm_ppi_version, "1.2") < 0)
+		obj = &tmp;
+	obj = tpm_eval_dsm(TPM_PPI_FN_GETACT, ACPI_TYPE_INTEGER, obj);
+	if (!obj) {
+		return -ENXIO;
+	} else {
+		ret = obj->integer.value;
+		ACPI_FREE(obj);
 	}
-	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;
 }
 
@@ -274,27 +193,14 @@ 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))
+	acpi_status status = -EINVAL;
+	union acpi_object *obj, *ret_obj;
+	u64 req, res;
+
+	obj = tpm_eval_dsm(TPM_PPI_FN_GETRSP, ACPI_TYPE_PACKAGE, NULL);
+	if (!obj)
 		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
@@ -302,115 +208,82 @@ static ssize_t tpm_show_ppi_response(struct device *dev,
 	 * 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;
+	ret_obj = obj->package.elements;
+	if (obj->package.count < 3 ||
+	    ret_obj[0].type != ACPI_TYPE_INTEGER ||
+	    ret_obj[1].type != ACPI_TYPE_INTEGER ||
+	    ret_obj[2].type != ACPI_TYPE_INTEGER)
 		goto cleanup;
-	}
-	if (ret_obj->integer.value) {
+
+	if (ret_obj[0].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)
+
+	req = ret_obj[1].integer.value;
+	res = ret_obj[2].integer.value;
+	if (req) {
+		if (res == 0)
 			status = scnprintf(buf, PAGE_SIZE, "%llu %s\n", req,
 					   "0: Success");
-		else if (ret_obj->integer.value == 0xFFFFFFF0)
+		else if (res == 0xFFFFFFF0)
 			status = scnprintf(buf, PAGE_SIZE, "%llu %s\n", req,
 					   "0xFFFFFFF0: User Abort");
-		else if (ret_obj->integer.value == 0xFFFFFFF1)
+		else if (res == 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)
+		else if (res >= 1 && res <= 0x00000FFF)
 			status = scnprintf(buf, PAGE_SIZE, "%llu %llu: %s\n",
-					   req, ret_obj->integer.value,
-					   "Corresponding TPM error");
+					   req, res, "Corresponding TPM error");
 		else
 			status = scnprintf(buf, PAGE_SIZE, "%llu %llu: %s\n",
-					   req, ret_obj->integer.value,
-					   "Error");
+					   req, res, "Error");
 	} else {
 		status = scnprintf(buf, PAGE_SIZE, "%llu: %s\n",
-				   ret_obj->integer.value, "No Recent Request");
+				   req, "No Recent Request");
 	}
+
 cleanup:
-	kfree(output.pointer);
+	ACPI_FREE(obj);
 	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[] = {
+	char *str = buf;
+	union acpi_object *obj, tmp;
+	union acpi_object argv = ACPI_INIT_DSM_ARGV4(1, &tmp);
+
+	static 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)
+	if (!acpi_check_dsm(tpm_ppi_handle, tpm_ppi_uuid, TPM_PPI_REVISION_ID,
+			    1 << TPM_PPI_FN_GETOPR))
 		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;
+	tmp.integer.type = ACPI_TYPE_INTEGER;
 	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))
+		tmp.integer.value = i;
+		obj = tpm_eval_dsm(TPM_PPI_FN_GETOPR, ACPI_TYPE_INTEGER, &argv);
+		if (!obj) {
 			return -ENOMEM;
+		} else {
+			ret = obj->integer.value;
+			ACPI_FREE(obj);
+		}
 
-		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;
 }
 
@@ -452,6 +325,12 @@ static struct attribute_group ppi_attr_grp = {
 
 int tpm_add_ppi(struct kobject *parent)
 {
+	/* Cache TPM ACPI handle and version string */
+	acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT, ACPI_UINT32_MAX,
+			    ppi_callback, NULL, NULL, &tpm_ppi_handle);
+	if (tpm_ppi_handle == NULL)
+		return -ENODEV;
+
 	return sysfs_create_group(parent, &ppi_attr_grp);
 }
 
diff --git a/drivers/gpu/drm/i915/intel_acpi.c b/drivers/gpu/drm/i915/intel_acpi.c
index 5325b25..d96eee1 100644
--- a/drivers/gpu/drm/i915/intel_acpi.c
+++ b/drivers/gpu/drm/i915/intel_acpi.c
@@ -10,8 +10,6 @@
 #include "i915_drv.h"
 
 #define INTEL_DSM_REVISION_ID 1 /* For Calpella anyway... */
-
-#define INTEL_DSM_FN_SUPPORTED_FUNCTIONS 0 /* No args */
 #define INTEL_DSM_FN_PLATFORM_MUX_INFO 1 /* No args */
 
 static struct intel_dsm_priv {
@@ -26,61 +24,6 @@ static const u8 intel_dsm_guid[] = {
 	0x0f, 0x13, 0x17, 0xb0, 0x1c, 0x2c
 };
 
-static int intel_dsm(acpi_handle handle, int func)
-{
-	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
-	struct acpi_object_list input;
-	union acpi_object params[4];
-	union acpi_object *obj;
-	u32 result;
-	int ret = 0;
-
-	input.count = 4;
-	input.pointer = params;
-	params[0].type = ACPI_TYPE_BUFFER;
-	params[0].buffer.length = sizeof(intel_dsm_guid);
-	params[0].buffer.pointer = (char *)intel_dsm_guid;
-	params[1].type = ACPI_TYPE_INTEGER;
-	params[1].integer.value = INTEL_DSM_REVISION_ID;
-	params[2].type = ACPI_TYPE_INTEGER;
-	params[2].integer.value = func;
-	params[3].type = ACPI_TYPE_PACKAGE;
-	params[3].package.count = 0;
-	params[3].package.elements = NULL;
-
-	ret = acpi_evaluate_object(handle, "_DSM", &input, &output);
-	if (ret) {
-		DRM_DEBUG_DRIVER("failed to evaluate _DSM: %d\n", ret);
-		return ret;
-	}
-
-	obj = (union acpi_object *)output.pointer;
-
-	result = 0;
-	switch (obj->type) {
-	case ACPI_TYPE_INTEGER:
-		result = obj->integer.value;
-		break;
-
-	case ACPI_TYPE_BUFFER:
-		if (obj->buffer.length == 4) {
-			result = (obj->buffer.pointer[0] |
-				(obj->buffer.pointer[1] <<  8) |
-				(obj->buffer.pointer[2] << 16) |
-				(obj->buffer.pointer[3] << 24));
-			break;
-		}
-	default:
-		ret = -EINVAL;
-		break;
-	}
-	if (result == 0x80000002)
-		ret = -ENODEV;
-
-	kfree(output.pointer);
-	return ret;
-}
-
 static char *intel_dsm_port_name(u8 id)
 {
 	switch (id) {
@@ -135,83 +78,56 @@ static char *intel_dsm_mux_type(u8 type)
 
 static void intel_dsm_platform_mux_info(void)
 {
-	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
-	struct acpi_object_list input;
-	union acpi_object params[4];
-	union acpi_object *pkg;
-	int i, ret;
-
-	input.count = 4;
-	input.pointer = params;
-	params[0].type = ACPI_TYPE_BUFFER;
-	params[0].buffer.length = sizeof(intel_dsm_guid);
-	params[0].buffer.pointer = (char *)intel_dsm_guid;
-	params[1].type = ACPI_TYPE_INTEGER;
-	params[1].integer.value = INTEL_DSM_REVISION_ID;
-	params[2].type = ACPI_TYPE_INTEGER;
-	params[2].integer.value = INTEL_DSM_FN_PLATFORM_MUX_INFO;
-	params[3].type = ACPI_TYPE_PACKAGE;
-	params[3].package.count = 0;
-	params[3].package.elements = NULL;
-
-	ret = acpi_evaluate_object(intel_dsm_priv.dhandle, "_DSM", &input,
-				   &output);
-	if (ret) {
-		DRM_DEBUG_DRIVER("failed to evaluate _DSM: %d\n", ret);
-		goto out;
+	int i;
+	union acpi_object *pkg, *connector_count;
+
+	pkg = acpi_evaluate_dsm_typed(intel_dsm_priv.dhandle, intel_dsm_guid,
+			INTEL_DSM_REVISION_ID, INTEL_DSM_FN_PLATFORM_MUX_INFO,
+			NULL, ACPI_TYPE_PACKAGE);
+	if (!pkg) {
+		DRM_DEBUG_DRIVER("failed to evaluate _DSM\n");
+		return;
 	}
 
-	pkg = (union acpi_object *)output.pointer;
-
-	if (pkg->type == ACPI_TYPE_PACKAGE) {
-		union acpi_object *connector_count = &pkg->package.elements[0];
-		DRM_DEBUG_DRIVER("MUX info connectors: %lld\n",
-			  (unsigned long long)connector_count->integer.value);
-		for (i = 1; i < pkg->package.count; i++) {
-			union acpi_object *obj = &pkg->package.elements[i];
-			union acpi_object *connector_id =
-				&obj->package.elements[0];
-			union acpi_object *info = &obj->package.elements[1];
-			DRM_DEBUG_DRIVER("Connector id: 0x%016llx\n",
-				  (unsigned long long)connector_id->integer.value);
-			DRM_DEBUG_DRIVER("  port id: %s\n",
-			       intel_dsm_port_name(info->buffer.pointer[0]));
-			DRM_DEBUG_DRIVER("  display mux info: %s\n",
-			       intel_dsm_mux_type(info->buffer.pointer[1]));
-			DRM_DEBUG_DRIVER("  aux/dc mux info: %s\n",
-			       intel_dsm_mux_type(info->buffer.pointer[2]));
-			DRM_DEBUG_DRIVER("  hpd mux info: %s\n",
-			       intel_dsm_mux_type(info->buffer.pointer[3]));
-		}
+	connector_count = &pkg->package.elements[0];
+	DRM_DEBUG_DRIVER("MUX info connectors: %lld\n",
+		  (unsigned long long)connector_count->integer.value);
+	for (i = 1; i < pkg->package.count; i++) {
+		union acpi_object *obj = &pkg->package.elements[i];
+		union acpi_object *connector_id = &obj->package.elements[0];
+		union acpi_object *info = &obj->package.elements[1];
+		DRM_DEBUG_DRIVER("Connector id: 0x%016llx\n",
+			  (unsigned long long)connector_id->integer.value);
+		DRM_DEBUG_DRIVER("  port id: %s\n",
+		       intel_dsm_port_name(info->buffer.pointer[0]));
+		DRM_DEBUG_DRIVER("  display mux info: %s\n",
+		       intel_dsm_mux_type(info->buffer.pointer[1]));
+		DRM_DEBUG_DRIVER("  aux/dc mux info: %s\n",
+		       intel_dsm_mux_type(info->buffer.pointer[2]));
+		DRM_DEBUG_DRIVER("  hpd mux info: %s\n",
+		       intel_dsm_mux_type(info->buffer.pointer[3]));
 	}
 
-out:
-	kfree(output.pointer);
+	ACPI_FREE(pkg);
 }
 
 static bool intel_dsm_pci_probe(struct pci_dev *pdev)
 {
 	acpi_handle dhandle;
-	int ret;
 
 	dhandle = ACPI_HANDLE(&pdev->dev);
 	if (!dhandle)
 		return false;
 
-	if (!acpi_has_method(dhandle, "_DSM")) {
+	if (!acpi_check_dsm(dhandle, intel_dsm_guid, INTEL_DSM_REVISION_ID,
+			    1 << INTEL_DSM_FN_PLATFORM_MUX_INFO)) {
 		DRM_DEBUG_KMS("no _DSM method for intel device\n");
 		return false;
 	}
 
-	ret = intel_dsm(dhandle, INTEL_DSM_FN_SUPPORTED_FUNCTIONS);
-	if (ret < 0) {
-		DRM_DEBUG_KMS("failed to get supported _DSM functions\n");
-		return false;
-	}
-
 	intel_dsm_priv.dhandle = dhandle;
-
 	intel_dsm_platform_mux_info();
+
 	return true;
 }
 
diff --git a/drivers/gpu/drm/nouveau/core/subdev/mxm/base.c b/drivers/gpu/drm/nouveau/core/subdev/mxm/base.c
index 1291204..13c5af8 100644
--- a/drivers/gpu/drm/nouveau/core/subdev/mxm/base.c
+++ b/drivers/gpu/drm/nouveau/core/subdev/mxm/base.c
@@ -87,55 +87,39 @@ mxm_shadow_dsm(struct nouveau_mxm *mxm, u8 version)
 		0xB8, 0x9C, 0x79, 0xB6, 0x2F, 0xD5, 0x56, 0x65
 	};
 	u32 mxms_args[] = { 0x00000000 };
-	union acpi_object args[4] = {
-		/* _DSM MUID */
-		{ .buffer.type = 3,
-		  .buffer.length = sizeof(muid),
-		  .buffer.pointer = muid,
-		},
-		/* spec says this can be zero to mean "highest revision", but
-		 * of course there's at least one bios out there which fails
-		 * unless you pass in exactly the version it supports..
-		 */
-		{ .integer.type = ACPI_TYPE_INTEGER,
-		  .integer.value = (version & 0xf0) << 4 | (version & 0x0f),
-		},
-		/* MXMS function */
-		{ .integer.type = ACPI_TYPE_INTEGER,
-		  .integer.value = 0x00000010,
-		},
-		/* Pointer to MXMS arguments */
-		{ .buffer.type = ACPI_TYPE_BUFFER,
-		  .buffer.length = sizeof(mxms_args),
-		  .buffer.pointer = (char *)mxms_args,
-		},
+	union acpi_object argv4 = {
+		.buffer.type = ACPI_TYPE_BUFFER,
+		.buffer.length = sizeof(mxms_args),
+		.buffer.pointer = (char *)mxms_args,
 	};
-	struct acpi_object_list list = { ARRAY_SIZE(args), args };
-	struct acpi_buffer retn = { ACPI_ALLOCATE_BUFFER, NULL };
 	union acpi_object *obj;
 	acpi_handle handle;
-	int ret;
+	int rev;
 
 	handle = ACPI_HANDLE(&device->pdev->dev);
 	if (!handle)
 		return false;
 
-	ret = acpi_evaluate_object(handle, "_DSM", &list, &retn);
-	if (ret) {
-		nv_debug(mxm, "DSM MXMS failed: %d\n", ret);
+	/*
+	 * spec says this can be zero to mean "highest revision", but
+	 * of course there's at least one bios out there which fails
+	 * unless you pass in exactly the version it supports..
+	 */
+	rev = (version & 0xf0) << 4 | (version & 0x0f);
+	obj = acpi_evaluate_dsm(handle, muid, rev, 0x00000010, &argv4);
+	if (!obj) {
+		nv_debug(mxm, "DSM MXMS failed\n");
 		return false;
 	}
 
-	obj = retn.pointer;
 	if (obj->type == ACPI_TYPE_BUFFER) {
 		mxm->mxms = kmemdup(obj->buffer.pointer,
 					 obj->buffer.length, GFP_KERNEL);
-	} else
-	if (obj->type == ACPI_TYPE_INTEGER) {
+	} else if (obj->type == ACPI_TYPE_INTEGER) {
 		nv_debug(mxm, "DSM MXMS returned 0x%llx\n", obj->integer.value);
 	}
 
-	kfree(obj);
+	ACPI_FREE(obj);
 	return mxm->mxms != NULL;
 }
 #endif
diff --git a/drivers/gpu/drm/nouveau/nouveau_acpi.c b/drivers/gpu/drm/nouveau/nouveau_acpi.c
index 1bc996c..3c14961 100644
--- a/drivers/gpu/drm/nouveau/nouveau_acpi.c
+++ b/drivers/gpu/drm/nouveau/nouveau_acpi.c
@@ -73,124 +73,66 @@ static const char nouveau_op_dsm_muid[] = {
 
 static int nouveau_optimus_dsm(acpi_handle handle, int func, int arg, uint32_t *result)
 {
-	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
-	struct acpi_object_list input;
-	union acpi_object params[4];
+	int i;
 	union acpi_object *obj;
-	int i, err;
 	char args_buff[4];
+	union acpi_object argv4 = {
+		.buffer.type = ACPI_TYPE_BUFFER,
+		.buffer.length = 4,
+		.buffer.pointer = args_buff
+	};
 
-	input.count = 4;
-	input.pointer = params;
-	params[0].type = ACPI_TYPE_BUFFER;
-	params[0].buffer.length = sizeof(nouveau_op_dsm_muid);
-	params[0].buffer.pointer = (char *)nouveau_op_dsm_muid;
-	params[1].type = ACPI_TYPE_INTEGER;
-	params[1].integer.value = 0x00000100;
-	params[2].type = ACPI_TYPE_INTEGER;
-	params[2].integer.value = func;
-	params[3].type = ACPI_TYPE_BUFFER;
-	params[3].buffer.length = 4;
 	/* ACPI is little endian, AABBCCDD becomes {DD,CC,BB,AA} */
 	for (i = 0; i < 4; i++)
 		args_buff[i] = (arg >> i * 8) & 0xFF;
-	params[3].buffer.pointer = args_buff;
 
-	err = acpi_evaluate_object(handle, "_DSM", &input, &output);
-	if (err) {
-		printk(KERN_INFO "failed to evaluate _DSM: %d\n", err);
-		return err;
-	}
-
-	obj = (union acpi_object *)output.pointer;
-
-	if (obj->type == ACPI_TYPE_INTEGER)
-		if (obj->integer.value == 0x80000002) {
-			return -ENODEV;
-		}
-
-	if (obj->type == ACPI_TYPE_BUFFER) {
-		if (obj->buffer.length == 4 && result) {
-			*result = 0;
+	*result = 0;
+	obj = acpi_evaluate_dsm_typed(handle, nouveau_op_dsm_muid, 0x00000100,
+				      func, &argv4, ACPI_TYPE_BUFFER);
+	if (!obj) {
+		acpi_handle_info(handle, "failed to evaluate _DSM\n");
+		return AE_ERROR;
+	} else {
+		if (obj->buffer.length == 4) {
 			*result |= obj->buffer.pointer[0];
 			*result |= (obj->buffer.pointer[1] << 8);
 			*result |= (obj->buffer.pointer[2] << 16);
 			*result |= (obj->buffer.pointer[3] << 24);
 		}
+		ACPI_FREE(obj);
 	}
 
-	kfree(output.pointer);
 	return 0;
 }
 
-static int nouveau_dsm(acpi_handle handle, int func, int arg, uint32_t *result)
+static int nouveau_dsm(acpi_handle handle, int func, int arg)
 {
-	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
-	struct acpi_object_list input;
-	union acpi_object params[4];
+	int ret = 0;
 	union acpi_object *obj;
-	int err;
-
-	input.count = 4;
-	input.pointer = params;
-	params[0].type = ACPI_TYPE_BUFFER;
-	params[0].buffer.length = sizeof(nouveau_dsm_muid);
-	params[0].buffer.pointer = (char *)nouveau_dsm_muid;
-	params[1].type = ACPI_TYPE_INTEGER;
-	params[1].integer.value = 0x00000102;
-	params[2].type = ACPI_TYPE_INTEGER;
-	params[2].integer.value = func;
-	params[3].type = ACPI_TYPE_INTEGER;
-	params[3].integer.value = arg;
-
-	err = acpi_evaluate_object(handle, "_DSM", &input, &output);
-	if (err) {
-		printk(KERN_INFO "failed to evaluate _DSM: %d\n", err);
-		return err;
-	}
-
-	obj = (union acpi_object *)output.pointer;
-
-	if (obj->type == ACPI_TYPE_INTEGER)
+	union acpi_object argv4 = {
+		.integer.type = ACPI_TYPE_INTEGER,
+		.integer.value = arg,
+	};
+
+	obj = acpi_evaluate_dsm_typed(handle, nouveau_dsm_muid, 0x00000102,
+				      func, &argv4, ACPI_TYPE_INTEGER);
+	if (!obj) {
+		acpi_handle_info(handle, "failed to evaluate _DSM\n");
+		return AE_ERROR;
+	} else {
 		if (obj->integer.value == 0x80000002)
-			return -ENODEV;
-
-	if (obj->type == ACPI_TYPE_BUFFER) {
-		if (obj->buffer.length == 4 && result) {
-			*result = 0;
-			*result |= obj->buffer.pointer[0];
-			*result |= (obj->buffer.pointer[1] << 8);
-			*result |= (obj->buffer.pointer[2] << 16);
-			*result |= (obj->buffer.pointer[3] << 24);
-		}
+			ret = -ENODEV;
+		ACPI_FREE(obj);
 	}
 
-	kfree(output.pointer);
-	return 0;
-}
-
-/* Returns 1 if a DSM function is usable and 0 otherwise */
-static int nouveau_test_dsm(acpi_handle test_handle,
-	int (*dsm_func)(acpi_handle, int, int, uint32_t *),
-	int sfnc)
-{
-	u32 result = 0;
-
-	/* Function 0 returns a Buffer containing available functions. The args
-	 * parameter is ignored for function 0, so just put 0 in it */
-	if (dsm_func(test_handle, 0, 0, &result))
-		return 0;
-
-	/* ACPI Spec v4 9.14.1: if bit 0 is zero, no function is supported. If
-	 * the n-th bit is enabled, function n is supported */
-	return result & 1 && result & (1 << sfnc);
+	return ret;
 }
 
 static int nouveau_dsm_switch_mux(acpi_handle handle, int mux_id)
 {
 	mxm_wmi_call_mxmx(mux_id == NOUVEAU_DSM_LED_STAMINA ? MXM_MXDS_ADAPTER_IGD : MXM_MXDS_ADAPTER_0);
 	mxm_wmi_call_mxds(mux_id == NOUVEAU_DSM_LED_STAMINA ? MXM_MXDS_ADAPTER_IGD : MXM_MXDS_ADAPTER_0);
-	return nouveau_dsm(handle, NOUVEAU_DSM_LED, mux_id, NULL);
+	return nouveau_dsm(handle, NOUVEAU_DSM_LED, mux_id);
 }
 
 static int nouveau_dsm_set_discrete_state(acpi_handle handle, enum vga_switcheroo_state state)
@@ -200,7 +142,7 @@ static int nouveau_dsm_set_discrete_state(acpi_handle handle, enum vga_switchero
 		arg = NOUVEAU_DSM_POWER_SPEED;
 	else
 		arg = NOUVEAU_DSM_POWER_STAMINA;
-	nouveau_dsm(handle, NOUVEAU_DSM_POWER, arg, NULL);
+	nouveau_dsm(handle, NOUVEAU_DSM_POWER, arg);
 	return 0;
 }
 
@@ -260,11 +202,12 @@ static int nouveau_dsm_pci_probe(struct pci_dev *pdev)
 		nouveau_dsm_priv.other_handle = dhandle;
 		return false;
 	}
-	if (nouveau_test_dsm(dhandle, nouveau_dsm, NOUVEAU_DSM_POWER))
+	if (acpi_check_dsm(dhandle, nouveau_dsm_muid, 0x00000102,
+			   1 << NOUVEAU_DSM_POWER))
 		retval |= NOUVEAU_DSM_HAS_MUX;
 
-	if (nouveau_test_dsm(dhandle, nouveau_optimus_dsm,
-		NOUVEAU_DSM_OPTIMUS_CAPS))
+	if (acpi_check_dsm(dhandle, nouveau_op_dsm_muid, 0x00000100,
+			   1 << NOUVEAU_DSM_OPTIMUS_CAPS))
 		retval |= NOUVEAU_DSM_HAS_OPT;
 
 	if (retval & NOUVEAU_DSM_HAS_OPT) {
diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
index 5f7e55f..d22668f 100644
--- a/drivers/hid/i2c-hid/i2c-hid.c
+++ b/drivers/hid/i2c-hid/i2c-hid.c
@@ -850,37 +850,23 @@ static int i2c_hid_acpi_pdata(struct i2c_client *client,
 		0xF7, 0xF6, 0xDF, 0x3C, 0x67, 0x42, 0x55, 0x45,
 		0xAD, 0x05, 0xB3, 0x0A, 0x3D, 0x89, 0x38, 0xDE,
 	};
-	union acpi_object params[4];
-	struct acpi_object_list input;
+	union acpi_object *obj;
 	struct acpi_device *adev;
-	unsigned long long value;
 	acpi_handle handle;
 
 	handle = ACPI_HANDLE(&client->dev);
 	if (!handle || acpi_bus_get_device(handle, &adev))
 		return -ENODEV;
 
-	input.count = ARRAY_SIZE(params);
-	input.pointer = params;
-
-	params[0].type = ACPI_TYPE_BUFFER;
-	params[0].buffer.length = sizeof(i2c_hid_guid);
-	params[0].buffer.pointer = i2c_hid_guid;
-	params[1].type = ACPI_TYPE_INTEGER;
-	params[1].integer.value = 1;
-	params[2].type = ACPI_TYPE_INTEGER;
-	params[2].integer.value = 1; /* HID function */
-	params[3].type = ACPI_TYPE_PACKAGE;
-	params[3].package.count = 0;
-	params[3].package.elements = NULL;
-
-	if (ACPI_FAILURE(acpi_evaluate_integer(handle, "_DSM", &input,
-								&value))) {
+	obj = acpi_evaluate_dsm_typed(handle, i2c_hid_guid, 1, 1, NULL,
+				      ACPI_TYPE_INTEGER);
+	if (!obj) {
 		dev_err(&client->dev, "device _DSM execution failed\n");
 		return -ENODEV;
 	}
 
-	pdata->hid_descriptor_address = value;
+	pdata->hid_descriptor_address = obj->integer.value;
+	ACPI_FREE(obj);
 
 	return 0;
 }
diff --git a/drivers/pci/pci-label.c b/drivers/pci/pci-label.c
index dbafcc8..d2d1cec 100644
--- a/drivers/pci/pci-label.c
+++ b/drivers/pci/pci-label.c
@@ -186,7 +186,6 @@ static const char device_label_dsm_uuid[] = {
 };
 
 enum acpi_attr_enum {
-	ACPI_ATTR_NONE = 0,
 	ACPI_ATTR_LABEL_SHOW,
 	ACPI_ATTR_INDEX_SHOW,
 };
@@ -194,84 +193,61 @@ enum acpi_attr_enum {
 static void dsm_label_utf16s_to_utf8s(union acpi_object *obj, char *buf)
 {
 	int len;
-	len = utf16s_to_utf8s((const wchar_t *)obj->
-			      package.elements[1].string.pointer,
-			      obj->package.elements[1].string.length,
+	len = utf16s_to_utf8s((const wchar_t *)obj->string.pointer,
+			      obj->string.length,
 			      UTF16_LITTLE_ENDIAN,
 			      buf, PAGE_SIZE);
 	buf[len] = '\n';
 }
 
 static int
-dsm_get_label(acpi_handle handle, int func,
-	      struct acpi_buffer *output,
-	      char *buf, enum acpi_attr_enum attribute)
+dsm_get_label(struct device *dev, char *buf, enum acpi_attr_enum attr)
 {
-	struct acpi_object_list input;
-	union acpi_object params[4];
-	union acpi_object *obj;
-	int len = 0;
-
-	int err;
-
-	input.count = 4;
-	input.pointer = params;
-	params[0].type = ACPI_TYPE_BUFFER;
-	params[0].buffer.length = sizeof(device_label_dsm_uuid);
-	params[0].buffer.pointer = (char *)device_label_dsm_uuid;
-	params[1].type = ACPI_TYPE_INTEGER;
-	params[1].integer.value = 0x02;
-	params[2].type = ACPI_TYPE_INTEGER;
-	params[2].integer.value = func;
-	params[3].type = ACPI_TYPE_PACKAGE;
-	params[3].package.count = 0;
-	params[3].package.elements = NULL;
-
-	err = acpi_evaluate_object(handle, "_DSM", &input, output);
-	if (err)
+	acpi_handle handle;
+	union acpi_object *obj, *tmp;
+	int len = -1;
+
+	handle = ACPI_HANDLE(dev);
+	if (!handle)
 		return -1;
 
-	obj = (union acpi_object *)output->pointer;
-
-	switch (obj->type) {
-	case ACPI_TYPE_PACKAGE:
-		if (obj->package.count != 2)
-			break;
-		len = obj->package.elements[0].integer.value;
-		if (buf) {
-			if (attribute == ACPI_ATTR_INDEX_SHOW)
-				scnprintf(buf, PAGE_SIZE, "%llu\n",
-				obj->package.elements[0].integer.value);
-			else if (attribute == ACPI_ATTR_LABEL_SHOW)
-				dsm_label_utf16s_to_utf8s(obj, buf);
-			kfree(output->pointer);
-			return strlen(buf);
-		}
-		kfree(output->pointer);
-		return len;
-	break;
-	default:
-		kfree(output->pointer);
+	obj = acpi_evaluate_dsm(handle, device_label_dsm_uuid, 0x2,
+				DEVICE_LABEL_DSM, NULL);
+	if (!obj)
+		return -1;
+
+	tmp = obj->package.elements;
+	if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 2 &&
+	    tmp[0].type == ACPI_TYPE_INTEGER &&
+	    tmp[1].type == ACPI_TYPE_STRING) {
+		/*
+		 * The second string element is optional even when
+		 * this _DSM is implemented; when not implemented,
+		 * this entry must return a null string.
+		 */
+		if (attr == ACPI_ATTR_INDEX_SHOW)
+			scnprintf(buf, PAGE_SIZE, "%llu\n", tmp->integer.value);
+		else if (attr == ACPI_ATTR_LABEL_SHOW)
+			dsm_label_utf16s_to_utf8s(tmp + 1, buf);
+		len = strlen(buf) > 0 ? strlen(buf) : -1;
 	}
-	return -1;
+
+	ACPI_FREE(obj);
+
+	return len;
 }
 
 static bool
 device_has_dsm(struct device *dev)
 {
 	acpi_handle handle;
-	struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
 
 	handle = ACPI_HANDLE(dev);
-
 	if (!handle)
-		return FALSE;
+		return false;
 
-	if (dsm_get_label(handle, DEVICE_LABEL_DSM, &output, NULL,
-			  ACPI_ATTR_NONE) > 0)
-		return TRUE;
-
-	return FALSE;
+	return !!acpi_check_dsm(handle, device_label_dsm_uuid, 0x2,
+				1 << DEVICE_LABEL_DSM);
 }
 
 static umode_t
@@ -290,44 +266,13 @@ acpi_index_string_exist(struct kobject *kobj, struct attribute *attr, int n)
 static ssize_t
 acpilabel_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
-	struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
-	acpi_handle handle;
-	int length;
-
-	handle = ACPI_HANDLE(dev);
-
-	if (!handle)
-		return -1;
-
-	length = dsm_get_label(handle, DEVICE_LABEL_DSM,
-			       &output, buf, ACPI_ATTR_LABEL_SHOW);
-
-	if (length < 1)
-		return -1;
-
-	return length;
+	return dsm_get_label(dev, buf, ACPI_ATTR_LABEL_SHOW);
 }
 
 static ssize_t
 acpiindex_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
-	struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
-	acpi_handle handle;
-	int length;
-
-	handle = ACPI_HANDLE(dev);
-
-	if (!handle)
-		return -1;
-
-	length = dsm_get_label(handle, DEVICE_LABEL_DSM,
-			       &output, buf, ACPI_ATTR_INDEX_SHOW);
-
-	if (length < 0)
-		return -1;
-
-	return length;
-
+	return dsm_get_label(dev, buf, ACPI_ATTR_INDEX_SHOW);
 }
 
 static struct device_attribute acpi_attr_label = {
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index e4ab7be..8256eb4 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -64,6 +64,32 @@ bool acpi_ata_match(acpi_handle handle);
 bool acpi_bay_match(acpi_handle handle);
 bool acpi_dock_match(acpi_handle handle);
 
+bool acpi_check_dsm(acpi_handle handle, const u8 *uuid, int rev, u64 funcs);
+union acpi_object *acpi_evaluate_dsm(acpi_handle handle, const u8 *uuid,
+			int rev, int func, union acpi_object *argv4);
+
+static inline union acpi_object *
+acpi_evaluate_dsm_typed(acpi_handle handle, const u8 *uuid, int rev, int func,
+			union acpi_object *argv4, acpi_object_type type)
+{
+	union acpi_object *obj;
+
+	obj = acpi_evaluate_dsm(handle, uuid, rev, func, argv4);
+	if (obj && obj->type != type) {
+		ACPI_FREE(obj);
+		obj = NULL;
+	}
+
+	return obj;
+}
+
+#define	ACPI_INIT_DSM_ARGV4(cnt, eles)			\
+	{						\
+	  .package.type = ACPI_TYPE_PACKAGE,		\
+	  .package.count = (cnt),			\
+	  .package.elements = (eles)			\
+	}
+
 #ifdef CONFIG_ACPI
 
 #include <linux/proc_fs.h>