spi: Enhance and export helpers for ACPI resources

Merge series from Stefan Binding <sbinding@opensource.cirrus.com>:

This series enhances the helpers for ACPI resources to cope with
multiple resources and exports them for use in the x86 platform code's
multi-instantiate driver.

include/linux/spi/spi.h

@@ -16,6 +16,7 @@
 #include <linux/gpio/consumer.h>
 
 #include <uapi/linux/spi/spi.h>
+#include <linux/acpi.h>
 
 struct dma_chan;
 struct software_node;
@@ -759,6 +760,13 @@ 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)
+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);
+#endif
+
 /*
  * SPI resource management while processing a SPI message
  */
@@ -1452,7 +1460,19 @@ spi_register_board_info(struct spi_board_info const *info, unsigned n)
  * use spi_new_device() to describe each device.  You can also call
  * spi_unregister_device() to start making that device vanish, but
  * normally that would be handled by spi_unregister_controller().
+ *
+ * You can also use spi_alloc_device() and spi_add_device() to use a two
+ * stage registration sequence for each spi_device. This gives the caller
+ * some more control over the spi_device structure before it is registered,
+ * but requires that caller to initialize fields that would otherwise
+ * be defined using the board info.
  */
+extern struct spi_device *
+spi_alloc_device(struct spi_controller *ctlr);
+
+extern int
+spi_add_device(struct spi_device *spi);
+
 extern struct spi_device *
 spi_new_device(struct spi_controller *, struct spi_board_info *);