Merge tag 'spi-acpi-lookup-dummy' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi into topic/cirrus-hp-g12

spi: Add empty versions of ACPI lookup functions

A patch from Richard Fitzgerald adding dummy versions of the ACPI lookup
functions for SPI:

    Provide empty versions of acpi_spi_count_resources(),
    acpi_spi_device_alloc() and acpi_spi_find_controller_by_adev()
    if the real functions are not being built.

    This commit fixes two problems with the original definitions:

    1) There wasn't an empty version of these functions
    2) The #if only depended on CONFIG_ACPI. But the functions are implemented
       in the core spi.c so CONFIG_SPI_MASTER must also be enabled for the real
       functions to exist.

include/linux/spi/spi.h

@@ -902,12 +902,29 @@ extern int devm_spi_register_controller(struct device *dev,
 					struct spi_controller *ctlr);
 extern void spi_unregister_controller(struct spi_controller *ctlr);
 
-#if IS_ENABLED(CONFIG_ACPI)
+#if IS_ENABLED(CONFIG_ACPI) && IS_ENABLED(CONFIG_SPI_MASTER)
 extern struct spi_controller *acpi_spi_find_controller_by_adev(struct acpi_device *adev);
 extern struct spi_device *acpi_spi_device_alloc(struct spi_controller *ctlr,
 						struct acpi_device *adev,
 						int index);
 int acpi_spi_count_resources(struct acpi_device *adev);
+#else
+static inline struct spi_controller *acpi_spi_find_controller_by_adev(struct acpi_device *adev)
+{
+	return NULL;
+}
+
+static inline struct spi_device *acpi_spi_device_alloc(struct spi_controller *ctlr,
+						       struct acpi_device *adev,
+						       int index)
+{
+	return ERR_PTR(-ENODEV);
+}
+
+static inline int acpi_spi_count_resources(struct acpi_device *adev)
+{
+	return 0;
+}
 #endif
 
 /*