ASoC: soc-acpi: add get_function_tplg_files ops

We always use a single topology that contains all PCM devices belonging
to a machine configuration.
However, with SDCA, we want to be able to load function topologies based
on the supported device functions. This change is in preparation for
loading those function topologies.

Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>

Author: bardliao

include/sound/soc-acpi.h

@@ -10,6 +10,7 @@
 #include <linux/acpi.h>
 #include <linux/mod_devicetable.h>
 #include <linux/soundwire/sdw.h>
+#include <sound/soc.h>
 
 struct snd_soc_acpi_package_context {
 	char *name;           /* package name */
@@ -193,6 +194,15 @@ struct snd_soc_acpi_link_adr {
  *  is not constant since this field may be updated at run-time
  * @sof_tplg_filename: Sound Open Firmware topology file name, if enabled
  * @tplg_quirk_mask: quirks to select different topology files dynamically
+ * @get_function_tplg_files: This is an optional callback, if specified then instead of
+ *	the single sof_tplg_filename the callback will return the list of function topology
+ *	files to be loaded.
+ *	Return value: The number of the files or negative ERRNO. 0 means that the single topology
+ *		      file should be used, no function topology split can be used on the machine.
+ *	@card: the pointer of the card
+ *	@mach: the pointer of the machine driver
+ *	@prefix: the prefix of the topology file name. Typically, it is the path.
+ *	@tplg_files: the pointer of the array of the topology file names.
  */
 /* Descriptor for SST ASoC machine driver */
 struct snd_soc_acpi_mach {
@@ -212,6 +222,9 @@ struct snd_soc_acpi_mach {
 	struct snd_soc_acpi_mach_params mach_params;
 	const char *sof_tplg_filename;
 	const u32 tplg_quirk_mask;
+	int (*get_function_tplg_files)(struct snd_soc_card *card,
+				       const struct snd_soc_acpi_mach *mach,
+				       const char *prefix, const char ***tplg_files);
 };
 
 #define SND_SOC_ACPI_MAX_CODECS 3