ACPI: Introduce has_acpi_companion()

Now that the ACPI companions of devices are represented by pointers
to struct fwnode_handle, it is not quite efficient to check whether
or not an ACPI companion of a device is present by evaluating the
ACPI_COMPANION() macro.

For this reason, introduce a special static inline routine for that,
has_acpi_companion(), and update the code to use it where applicable.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
index f774c65..39c485b 100644
--- a/drivers/acpi/glue.c
+++ b/drivers/acpi/glue.c
@@ -168,7 +168,7 @@
 	unsigned int node_id;
 	int retval = -EINVAL;
 
-	if (ACPI_COMPANION(dev)) {
+	if (has_acpi_companion(dev)) {
 		if (acpi_dev) {
 			dev_warn(dev, "ACPI companion already set\n");
 			return -EINVAL;
@@ -220,7 +220,7 @@
 	list_add(&physical_node->node, physnode_list);
 	acpi_dev->physical_node_count++;
 
-	if (!ACPI_COMPANION(dev))
+	if (!has_acpi_companion(dev))
 		ACPI_COMPANION_SET(dev, acpi_dev);
 
 	acpi_physnode_link_name(physical_node_name, node_id);
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index c270f5f..538d691 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -166,7 +166,7 @@
 	/* fast mode by default because of legacy reasons */
 	clk_freq = 400000;
 
-	if (ACPI_COMPANION(&pdev->dev)) {
+	if (has_acpi_companion(&pdev->dev)) {
 		dw_i2c_acpi_configure(pdev);
 	} else if (pdev->dev.of_node) {
 		of_property_read_u32(pdev->dev.of_node,
@@ -286,7 +286,7 @@
 	pm_runtime_put(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 
-	if (ACPI_COMPANION(&pdev->dev))
+	if (has_acpi_companion(&pdev->dev))
 		dw_i2c_acpi_unconfigure(pdev);
 
 	return 0;
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index ae4c1a8..591b843 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -684,7 +684,7 @@
 	if (dev_is_pci(dev)) {
 		pdev = to_pci_dev(dev);
 		segment = pci_domain_nr(pdev->bus);
-	} else if (ACPI_COMPANION(dev))
+	} else if (has_acpi_companion(dev))
 		dev = &ACPI_COMPANION(dev)->dev;
 
 	rcu_read_lock();
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 402ddbd..ec488d0 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -58,6 +58,11 @@
 	acpi_fwnode_handle(adev) : NULL
 #define ACPI_HANDLE(dev)		acpi_device_handle(ACPI_COMPANION(dev))
 
+static inline bool has_acpi_companion(struct device *dev)
+{
+	return is_acpi_node(dev->fwnode);
+}
+
 static inline void acpi_preset_companion(struct device *dev,
 					 struct acpi_device *parent, u64 addr)
 {
@@ -472,6 +477,11 @@
 	return NULL;
 }
 
+static inline bool has_acpi_companion(struct device *dev)
+{
+	return false;
+}
+
 static inline const char *acpi_dev_name(struct acpi_device *adev)
 {
 	return NULL;