Merge branch 'acpi-dev'

Merge changes regarding the management of ACPI device objects for
6.1-rc1:

 - Rename ACPI device object reference counting functions (Rafael
   Wysocki).

 - Rearrange ACPI device object initialization code (Rafael Wysocki).

 - Drop parent field from struct acpi_device (Rafael Wysocki).

 - Extend the the int3472-tps68470 driver to support multiple consumers
   of a single TPS68470 along with the requisite framework-level
   support (Daniel Scally).

* acpi-dev:
  platform/x86: int3472: Add board data for Surface Go2 IR camera
  platform/x86: int3472: Support multiple gpio lookups in board data
  platform/x86: int3472: Support multiple clock consumers
  ACPI: bus: Add iterator for dependent devices
  ACPI: scan: Add acpi_dev_get_next_consumer_dev()
  ACPI: property: Use acpi_dev_parent()
  ACPI: Drop redundant acpi_dev_parent() header
  ACPI: PM: Fix NULL argument handling in acpi_device_get/set_power()
  ACPI: Drop parent field from struct acpi_device
  ACPI: scan: Eliminate __acpi_device_add()
  ACPI: scan: Rearrange initialization of ACPI device objects
  ACPI: scan: Rename acpi_bus_get_parent() and rearrange it
  ACPI: Rename acpi_bus_get/put_acpi_device()

12 files changed, 127 insertions, 92 deletions

diff --git a/drivers/acpi/acpi_amba.c b/drivers/acpi/acpi_amba.c
index ab8a4e0191b1..9d69546db2a4 100644
--- a/drivers/acpi/acpi_amba.c
+++ b/drivers/acpi/acpi_amba.c
@@ -48,6 +48,7 @@ static void amba_register_dummy_clk(void)
 static int amba_handler_attach(struct acpi_device *adev,
 				const struct acpi_device_id *id)
 {
+	struct acpi_device *parent = acpi_dev_parent(adev);
 	struct amba_device *dev;
 	struct resource_entry *rentry;
 	struct list_head resource_list;
@@ -97,8 +98,8 @@ static int amba_handler_attach(struct acpi_device *adev,
 	 * attached to it, that physical device should be the parent of
 	 * the amba device we are about to create.
 	 */
-	if (adev->parent)
-		dev->dev.parent = acpi_get_first_physical_node(adev->parent);
+	if (parent)
+		dev->dev.parent = acpi_get_first_physical_node(parent);
 
 	ACPI_COMPANION_SET(&dev->dev, adev);
 
diff --git a/drivers/acpi/acpi_platform.c b/drivers/acpi/acpi_platform.c
index de3cbf152dee..1a1c78b23fba 100644
--- a/drivers/acpi/acpi_platform.c
+++ b/drivers/acpi/acpi_platform.c
@@ -78,7 +78,7 @@ static void acpi_platform_fill_resource(struct acpi_device *adev,
 	 * If the device has parent we need to take its resources into
 	 * account as well because this device might consume part of those.
 	 */
-	parent = acpi_get_first_physical_node(adev->parent);
+	parent = acpi_get_first_physical_node(acpi_dev_parent(adev));
 	if (parent && dev_is_pci(parent))
 		dest->parent = pci_find_resource(to_pci_dev(parent), dest);
 }
@@ -97,6 +97,7 @@ static void acpi_platform_fill_resource(struct acpi_device *adev,
 struct platform_device *acpi_create_platform_device(struct acpi_device *adev,
 						    const struct property_entry *properties)
 {
+	struct acpi_device *parent = acpi_dev_parent(adev);
 	struct platform_device *pdev = NULL;
 	struct platform_device_info pdevinfo;
 	struct resource_entry *rentry;
@@ -137,8 +138,7 @@ struct platform_device *acpi_create_platform_device(struct acpi_device *adev,
 	 * attached to it, that physical device should be the parent of the
 	 * platform device we are about to create.
 	 */
-	pdevinfo.parent = adev->parent ?
-		acpi_get_first_physical_node(adev->parent) : NULL;
+	pdevinfo.parent = parent ? acpi_get_first_physical_node(parent) : NULL;
 	pdevinfo.name = dev_name(&adev->dev);
 	pdevinfo.id = -1;
 	pdevinfo.res = resources;
diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c
index 5cbe2196176d..92a6c6f9a9a7 100644
--- a/drivers/acpi/acpi_video.c
+++ b/drivers/acpi/acpi_video.c
@@ -2030,7 +2030,7 @@ static int acpi_video_bus_add(struct acpi_device *device)
 	acpi_status status;
 
 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE,
-				device->parent->handle, 1,
+				acpi_dev_parent(device)->handle, 1,
 				acpi_video_bus_match, NULL,
 				device, NULL);
 	if (status == AE_ALREADY_EXISTS) {
diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index c0d20d997891..f43c6a4b0827 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -511,7 +511,7 @@ static void acpi_bus_notify(acpi_handle handle, u32 type, void *data)
 		break;
 	}
 
-	adev = acpi_bus_get_acpi_device(handle);
+	adev = acpi_get_acpi_dev(handle);
 	if (!adev)
 		goto err;
 
@@ -524,14 +524,14 @@ static void acpi_bus_notify(acpi_handle handle, u32 type, void *data)
 	}
 
 	if (!hotplug_event) {
-		acpi_bus_put_acpi_device(adev);
+		acpi_put_acpi_dev(adev);
 		return;
 	}
 
 	if (ACPI_SUCCESS(acpi_hotplug_schedule(adev, type)))
 		return;
 
-	acpi_bus_put_acpi_device(adev);
+	acpi_put_acpi_dev(adev);
 
  err:
 	acpi_evaluate_ost(handle, type, ost_code, NULL);
diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index 9dce1245689c..3aca67cf9ce5 100644
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -75,15 +75,17 @@ static int acpi_dev_pm_explicit_get(struct acpi_device *device, int *state)
 int acpi_device_get_power(struct acpi_device *device, int *state)
 {
 	int result = ACPI_STATE_UNKNOWN;
+	struct acpi_device *parent;
 	int error;
 
 	if (!device || !state)
 		return -EINVAL;
 
+	parent = acpi_dev_parent(device);
+
 	if (!device->flags.power_manageable) {
 		/* TBD: Non-recursive algorithm for walking up hierarchy. */
-		*state = device->parent ?
-			device->parent->power.state : ACPI_STATE_D0;
+		*state = parent ? parent->power.state : ACPI_STATE_D0;
 		goto out;
 	}
 
@@ -122,10 +124,10 @@ int acpi_device_get_power(struct acpi_device *device, int *state)
 	 * point, the fact that the device is in D0 implies that the parent has
 	 * to be in D0 too, except if ignore_parent is set.
 	 */
-	if (!device->power.flags.ignore_parent && device->parent
-	    && device->parent->power.state == ACPI_STATE_UNKNOWN
-	    && result == ACPI_STATE_D0)
-		device->parent->power.state = ACPI_STATE_D0;
+	if (!device->power.flags.ignore_parent && parent &&
+	    parent->power.state == ACPI_STATE_UNKNOWN &&
+	    result == ACPI_STATE_D0)
+		parent->power.state = ACPI_STATE_D0;
 
 	*state = result;
 
@@ -191,13 +193,17 @@ int acpi_device_set_power(struct acpi_device *device, int state)
 		return -ENODEV;
 	}
 
-	if (!device->power.flags.ignore_parent && device->parent &&
-	    state < device->parent->power.state) {
-		acpi_handle_debug(device->handle,
-				  "Cannot transition to %s for parent in %s\n",
-				  acpi_power_state_string(state),
-				  acpi_power_state_string(device->parent->power.state));
-		return -ENODEV;
+	if (!device->power.flags.ignore_parent) {
+		struct acpi_device *parent;
+
+		parent = acpi_dev_parent(device);
+		if (parent && state < parent->power.state) {
+			acpi_handle_debug(device->handle,
+					  "Cannot transition to %s for parent in %s\n",
+					  acpi_power_state_string(state),
+					  acpi_power_state_string(parent->power.state));
+			return -ENODEV;
+		}
 	}
 
 	/*
@@ -497,7 +503,7 @@ static void acpi_pm_notify_handler(acpi_handle handle, u32 val, void *not_used)
 
 	acpi_handle_debug(handle, "Wake notify\n");
 
-	adev = acpi_bus_get_acpi_device(handle);
+	adev = acpi_get_acpi_dev(handle);
 	if (!adev)
 		return;
 
@@ -515,7 +521,7 @@ static void acpi_pm_notify_handler(acpi_handle handle, u32 val, void *not_used)
 
 	mutex_unlock(&acpi_pm_notifier_lock);
 
-	acpi_bus_put_acpi_device(adev);
+	acpi_put_acpi_dev(adev);
 }
 
 /**
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 628bf8f18130..219c02df9a08 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -102,10 +102,10 @@ struct acpi_device_bus_id {
 	struct list_head node;
 };
 
-int acpi_device_add(struct acpi_device *device,
-		    void (*release)(struct device *));
 void acpi_init_device_object(struct acpi_device *device, acpi_handle handle,
-			     int type);
+			     int type, void (*release)(struct device *));
+int acpi_tie_acpi_dev(struct acpi_device *adev);
+int acpi_device_add(struct acpi_device *device);
 int acpi_device_setup_files(struct acpi_device *dev);
 void acpi_device_remove_files(struct acpi_device *dev);
 void acpi_device_add_finalize(struct acpi_device *device);
diff --git a/drivers/acpi/irq.c b/drivers/acpi/irq.c
index dabe45eba055..4db5bb587599 100644
--- a/drivers/acpi/irq.c
+++ b/drivers/acpi/irq.c
@@ -118,12 +118,12 @@ acpi_get_irq_source_fwhandle(const struct acpi_resource_source *source,
 	if (WARN_ON(ACPI_FAILURE(status)))
 		return NULL;
 
-	device = acpi_bus_get_acpi_device(handle);
+	device = acpi_get_acpi_dev(handle);
 	if (WARN_ON(!device))
 		return NULL;
 
 	result = &device->fwnode;
-	acpi_bus_put_acpi_device(device);
+	acpi_put_acpi_dev(device);
 	return result;
 }
 
diff --git a/drivers/acpi/power.c b/drivers/acpi/power.c
index 8c4a73a1351e..f2588aba8421 100644
--- a/drivers/acpi/power.c
+++ b/drivers/acpi/power.c
@@ -944,13 +944,15 @@ struct acpi_device *acpi_add_power_resource(acpi_handle handle)
 		return NULL;
 
 	device = &resource->device;
-	acpi_init_device_object(device, handle, ACPI_BUS_TYPE_POWER);
+	acpi_init_device_object(device, handle, ACPI_BUS_TYPE_POWER,
+				acpi_release_power_resource);
 	mutex_init(&resource->resource_lock);
 	INIT_LIST_HEAD(&resource->list_node);
 	INIT_LIST_HEAD(&resource->dependents);
 	strcpy(acpi_device_name(device), ACPI_POWER_DEVICE_NAME);
 	strcpy(acpi_device_class(device), ACPI_POWER_CLASS);
 	device->power.state = ACPI_STATE_UNKNOWN;
+	device->flags.match_driver = true;
 
 	/* Evaluate the object to get the system level and resource order. */
 	status = acpi_evaluate_object(handle, NULL, NULL, &buffer);
@@ -967,8 +969,11 @@ struct acpi_device *acpi_add_power_resource(acpi_handle handle)
 
 	pr_info("%s [%s]\n", acpi_device_name(device), acpi_device_bid(device));
 
-	device->flags.match_driver = true;
-	result = acpi_device_add(device, acpi_release_power_resource);
+	result = acpi_tie_acpi_dev(device);
+	if (result)
+		goto err;
+
+	result = acpi_device_add(device);
 	if (result)
 		goto err;
 
diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
index d4c168ce428c..b8d9eb9a433e 100644
--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -304,8 +304,10 @@ static void acpi_init_of_compatible(struct acpi_device *adev)
 		ret = acpi_dev_get_property(adev, "compatible",
 					    ACPI_TYPE_STRING, &of_compatible);
 		if (ret) {
-			if (adev->parent
-			    && adev->parent->flags.of_compatible_ok)
+			struct acpi_device *parent;
+
+			parent = acpi_dev_parent(adev);
+			if (parent && parent->flags.of_compatible_ok)
 				goto out;
 
 			return;
@@ -1267,10 +1269,11 @@ acpi_node_get_parent(const struct fwnode_handle *fwnode)
 		return to_acpi_data_node(fwnode)->parent;
 	}
 	if (is_acpi_device_node(fwnode)) {
-		struct device *dev = to_acpi_device_node(fwnode)->dev.parent;
+		struct acpi_device *parent;
 
-		if (dev)
-			return acpi_fwnode_handle(to_acpi_device(dev));
+		parent = acpi_dev_parent(to_acpi_device_node(fwnode));
+		if (parent)
+			return acpi_fwnode_handle(parent);
 	}
 
 	return NULL;
diff --git a/drivers/acpi/sbs.c b/drivers/acpi/sbs.c
index 4938010fcac7..e6a01a8df1b8 100644
--- a/drivers/acpi/sbs.c
+++ b/drivers/acpi/sbs.c
@@ -632,7 +632,7 @@ static int acpi_sbs_add(struct acpi_device *device)
 
 	mutex_init(&sbs->lock);
 
-	sbs->hc = acpi_driver_data(device->parent);
+	sbs->hc = acpi_driver_data(acpi_dev_parent(device));
 	sbs->device = device;
 	strcpy(acpi_device_name(device), ACPI_SBS_DEVICE_NAME);
 	strcpy(acpi_device_class(device), ACPI_SBS_CLASS);
diff --git a/drivers/acpi/sbshc.c b/drivers/acpi/sbshc.c
index 7c62e149a7a1..340e0b61587e 100644
--- a/drivers/acpi/sbshc.c
+++ b/drivers/acpi/sbshc.c
@@ -266,7 +266,7 @@ static int acpi_smbus_hc_add(struct acpi_device *device)
 	mutex_init(&hc->lock);
 	init_waitqueue_head(&hc->wait);
 
-	hc->ec = acpi_driver_data(device->parent);
+	hc->ec = acpi_driver_data(acpi_dev_parent(device));
 	hc->offset = (val >> 8) & 0xff;
 	hc->query_bit = val & 0xff;
 	device->driver_data = hc;
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 42cec8120f18..d0277427e7ee 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -29,8 +29,6 @@ extern struct acpi_device *acpi_root;
 #define ACPI_BUS_HID			"LNXSYBUS"
 #define ACPI_BUS_DEVICE_NAME		"System Bus"
 
-#define ACPI_IS_ROOT_DEVICE(device)    (!(device)->parent)
-
 #define INVALID_ACPI_HANDLE	((acpi_handle)empty_zero_page)
 
 static const char *dummy_hid = "device";
@@ -429,7 +427,7 @@ void acpi_device_hotplug(struct acpi_device *adev, u32 src)
 	acpi_evaluate_ost(adev->handle, src, ost_code, NULL);
 
  out:
-	acpi_bus_put_acpi_device(adev);
+	acpi_put_acpi_dev(adev);
 	mutex_unlock(&acpi_scan_lock);
 	unlock_device_hotplug();
 }
@@ -599,11 +597,22 @@ static void get_acpi_device(void *dev)
 	acpi_dev_get(dev);
 }
 
-struct acpi_device *acpi_bus_get_acpi_device(acpi_handle handle)
+/**
+ * acpi_get_acpi_dev - Retrieve ACPI device object and reference count it.
+ * @handle: ACPI handle associated with the requested ACPI device object.
+ *
+ * Return a pointer to the ACPI device object associated with @handle and bump
+ * up that object's reference counter (under the ACPI Namespace lock), if
+ * present, or return NULL otherwise.
+ *
+ * The ACPI device object reference acquired by this function needs to be
+ * dropped via acpi_dev_put().
+ */
+struct acpi_device *acpi_get_acpi_dev(acpi_handle handle)
 {
 	return handle_to_device(handle, get_acpi_device);
 }
-EXPORT_SYMBOL_GPL(acpi_bus_get_acpi_device);
+EXPORT_SYMBOL_GPL(acpi_get_acpi_dev);
 
 static struct acpi_device_bus_id *acpi_device_bus_id_match(const char *dev_id)
 {
@@ -632,7 +641,7 @@ static int acpi_device_set_name(struct acpi_device *device,
 	return 0;
 }
 
-static int acpi_tie_acpi_dev(struct acpi_device *adev)
+int acpi_tie_acpi_dev(struct acpi_device *adev)
 {
 	acpi_handle handle = adev->handle;
 	acpi_status status;
@@ -662,8 +671,7 @@ static void acpi_store_pld_crc(struct acpi_device *adev)
 	ACPI_FREE(pld);
 }
 
-static int __acpi_device_add(struct acpi_device *device,
-			     void (*release)(struct device *))
+int acpi_device_add(struct acpi_device *device)
 {
 	struct acpi_device_bus_id *acpi_device_bus_id;
 	int result;
@@ -719,11 +727,6 @@ static int __acpi_device_add(struct acpi_device *device,
 
 	mutex_unlock(&acpi_device_lock);
 
-	if (device->parent)
-		device->dev.parent = &device->parent->dev;
-
-	device->dev.bus = &acpi_bus_type;
-	device->dev.release = release;
 	result = device_add(&device->dev);
 	if (result) {
 		dev_err(&device->dev, "Error registering device\n");
@@ -750,17 +753,6 @@ err_unlock:
 	return result;
 }
 
-int acpi_device_add(struct acpi_device *adev, void (*release)(struct device *))
-{
-	int ret;
-
-	ret = acpi_tie_acpi_dev(adev);
-	if (ret)
-		return ret;
-
-	return __acpi_device_add(adev, release);
-}
-
 /* --------------------------------------------------------------------------
                                  Device Enumeration
    -------------------------------------------------------------------------- */
@@ -805,10 +797,9 @@ static const char * const acpi_honor_dep_ids[] = {
 	NULL
 };
 
-static struct acpi_device *acpi_bus_get_parent(acpi_handle handle)
+static struct acpi_device *acpi_find_parent_acpi_dev(acpi_handle handle)
 {
-	struct acpi_device *device;
-	acpi_status status;
+	struct acpi_device *adev;
 
 	/*
 	 * Fixed hardware devices do not appear in the namespace and do not
@@ -819,13 +810,18 @@ static struct acpi_device *acpi_bus_get_parent(acpi_handle handle)
 		return acpi_root;
 
 	do {
+		acpi_status status;
+
 		status = acpi_get_parent(handle, &handle);
-		if (ACPI_FAILURE(status))
-			return status == AE_NULL_ENTRY ? NULL : acpi_root;
+		if (ACPI_FAILURE(status)) {
+			if (status != AE_NULL_ENTRY)
+				return acpi_root;
 
-		device = acpi_fetch_acpi_dev(handle);
-	} while (!device);
-	return device;
+			return NULL;
+		}
+		adev = acpi_fetch_acpi_dev(handle);
+	} while (!adev);
+	return adev;
 }
 
 acpi_status
@@ -1112,7 +1108,7 @@ static void acpi_device_get_busid(struct acpi_device *device)
 	 * The device's Bus ID is simply the object name.
 	 * TBD: Shouldn't this value be unique (within the ACPI namespace)?
 	 */
-	if (ACPI_IS_ROOT_DEVICE(device)) {
+	if (!acpi_dev_parent(device)) {
 		strcpy(device->pnp.bus_id, "ACPI");
 		return;
 	}
@@ -1648,7 +1644,7 @@ static void acpi_init_coherency(struct acpi_device *adev)
 {
 	unsigned long long cca = 0;
 	acpi_status status;
-	struct acpi_device *parent = adev->parent;
+	struct acpi_device *parent = acpi_dev_parent(adev);
 
 	if (parent && parent->flags.cca_seen) {
 		/*
@@ -1692,7 +1688,7 @@ static int acpi_check_serial_bus_slave(struct acpi_resource *ares, void *data)
 
 static bool acpi_is_indirect_io_slave(struct acpi_device *device)
 {
-	struct acpi_device *parent = device->parent;
+	struct acpi_device *parent = acpi_dev_parent(device);
 	static const struct acpi_device_id indirect_io_hosts[] = {
 		{"HISI0191", 0},
 		{}
@@ -1762,12 +1758,16 @@ static bool acpi_device_enumeration_by_parent(struct acpi_device *device)
 }
 
 void acpi_init_device_object(struct acpi_device *device, acpi_handle handle,
-			     int type)
+			     int type, void (*release)(struct device *))
 {
+	struct acpi_device *parent = acpi_find_parent_acpi_dev(handle);
+
 	INIT_LIST_HEAD(&device->pnp.ids);
 	device->device_type = type;
 	device->handle = handle;
-	device->parent = acpi_bus_get_parent(handle);
+	device->dev.parent = parent ? &parent->dev : NULL;
+	device->dev.release = release;
+	device->dev.bus = &acpi_bus_type;
 	fwnode_init(&device->fwnode, &acpi_device_fwnode_ops);
 	acpi_set_device_status(device, ACPI_STA_DEFAULT);
 	acpi_device_get_busid(device);
@@ -1821,7 +1821,7 @@ static int acpi_add_single_object(struct acpi_device **child,
 	if (!device)
 		return -ENOMEM;
 
-	acpi_init_device_object(device, handle, type);
+	acpi_init_device_object(device, handle, type, acpi_device_release);
 	/*
 	 * Getting the status is delayed till here so that we can call
 	 * acpi_bus_get_status() and use its quirk handling.  Note that
@@ -1851,7 +1851,7 @@ static int acpi_add_single_object(struct acpi_device **child,
 		mutex_unlock(&acpi_dep_list_lock);
 
 	if (!result)
-		result = __acpi_device_add(device, acpi_device_release);
+		result = acpi_device_add(device);
 
 	if (result) {
 		acpi_device_release(&device->dev);
@@ -1862,8 +1862,8 @@ static int acpi_add_single_object(struct acpi_device **child,
 	acpi_device_add_finalize(device);
 
 	acpi_handle_debug(handle, "Added as %s, parent %s\n",
-			  dev_name(&device->dev), device->parent ?
-				dev_name(&device->parent->dev) : "(null)");
+			  dev_name(&device->dev), device->dev.parent ?
+				dev_name(device->dev.parent) : "(null)");
 
 	*child = device;
 	return 0;
@@ -2235,11 +2235,24 @@ ok:
 	return 0;
 }
 
-static int acpi_dev_get_first_consumer_dev_cb(struct acpi_dep_data *dep, void *data)
+static int acpi_dev_get_next_consumer_dev_cb(struct acpi_dep_data *dep, void *data)
 {
-	struct acpi_device *adev;
+	struct acpi_device **adev_p = data;
+	struct acpi_device *adev = *adev_p;
+
+	/*
+	 * If we're passed a 'previous' consumer device then we need to skip
+	 * any consumers until we meet the previous one, and then NULL @data
+	 * so the next one can be returned.
+	 */
+	if (adev) {
+		if (dep->consumer == adev->handle)
+			*adev_p = NULL;
+
+		return 0;
+	}
 
-	adev = acpi_bus_get_acpi_device(dep->consumer);
+	adev = acpi_get_acpi_dev(dep->consumer);
 	if (adev) {
 		*(struct acpi_device **)data = adev;
 		return 1;
@@ -2292,7 +2305,7 @@ static bool acpi_scan_clear_dep_queue(struct acpi_device *adev)
 
 static int acpi_scan_clear_dep(struct acpi_dep_data *dep, void *data)
 {
-	struct acpi_device *adev = acpi_bus_get_acpi_device(dep->consumer);
+	struct acpi_device *adev = acpi_get_acpi_dev(dep->consumer);
 
 	if (adev) {
 		adev->dep_unmet--;
@@ -2368,25 +2381,32 @@ bool acpi_dev_ready_for_enumeration(const struct acpi_device *device)
 EXPORT_SYMBOL_GPL(acpi_dev_ready_for_enumeration);
 
 /**
- * acpi_dev_get_first_consumer_dev - Return ACPI device dependent on @supplier
+ * acpi_dev_get_next_consumer_dev - Return the next adev dependent on @supplier
  * @supplier: Pointer to the dependee device
+ * @start: Pointer to the current dependent device
  *
- * Returns the first &struct acpi_device which declares itself dependent on
+ * Returns the next &struct acpi_device which declares itself dependent on
  * @supplier via the _DEP buffer, parsed from the acpi_dep_list.
  *
- * The caller is responsible for putting the reference to adev when it is no
- * longer needed.
+ * If the returned adev is not passed as @start to this function, the caller is
+ * responsible for putting the reference to adev when it is no longer needed.
  */
-struct acpi_device *acpi_dev_get_first_consumer_dev(struct acpi_device *supplier)
+struct acpi_device *acpi_dev_get_next_consumer_dev(struct acpi_device *supplier,
+						   struct acpi_device *start)
 {
-	struct acpi_device *adev = NULL;
+	struct acpi_device *adev = start;
 
 	acpi_walk_dep_device_list(supplier->handle,
-				  acpi_dev_get_first_consumer_dev_cb, &adev);
+				  acpi_dev_get_next_consumer_dev_cb, &adev);
+
+	acpi_dev_put(start);
+
+	if (adev == start)
+		return NULL;
 
 	return adev;
 }
-EXPORT_SYMBOL_GPL(acpi_dev_get_first_consumer_dev);
+EXPORT_SYMBOL_GPL(acpi_dev_get_next_consumer_dev);
 
 /**
  * acpi_bus_scan - Add ACPI device node objects in a given namespace scope.