ALSA: hda: cirrus_scodec: Add KUnit test

Add a KUnit test for cirrus_scodec_get_speaker_id(). It is impractical
to have enough hardware with every possible permutation of speaker id.
So use a test harness to test all theoretically supported options.

The test harness consists of:
- a mock GPIO controller.
- a mock struct device to represent the scodec driver
- software nodes to provide the fwnode info that would normally come
  from ACPI.
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20230918095129.440-3-rf@opensource.cirrus.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/Kconfig

@@ -94,6 +94,18 @@ config SND_HDA_PATCH_LOADER
 config SND_HDA_CIRRUS_SCODEC
 	tristate
 
+config SND_HDA_CIRRUS_SCODEC_KUNIT_TEST
+	tristate "KUnit test for Cirrus side-codec library" if !KUNIT_ALL_TESTS
+	select SND_HDA_CIRRUS_SCODEC
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  This builds KUnit tests for the cirrus side-codec library.
+	  For more information on KUnit and unit tests in general,
+	  please refer to the KUnit documentation in
+	  Documentation/dev-tools/kunit/.
+	  If in doubt, say "N".
+
 config SND_HDA_SCODEC_CS35L41
 	tristate
 	select SND_HDA_GENERIC

sound/pci/hda/Makefile

@@ -29,6 +29,7 @@ snd-hda-codec-hdmi-objs :=	patch_hdmi.o hda_eld.o
 
 # side codecs
 snd-hda-cirrus-scodec-objs :=		cirrus_scodec.o
+snd-hda-cirrus-scodec-test-objs :=	cirrus_scodec_test.o
 snd-hda-scodec-cs35l41-objs :=		cs35l41_hda.o cs35l41_hda_property.o
 snd-hda-scodec-cs35l41-i2c-objs :=	cs35l41_hda_i2c.o
 snd-hda-scodec-cs35l41-spi-objs :=	cs35l41_hda_spi.o
@@ -58,6 +59,7 @@ obj-$(CONFIG_SND_HDA_CODEC_HDMI) += snd-hda-codec-hdmi.o
 
 # side codecs
 obj-$(CONFIG_SND_HDA_CIRRUS_SCODEC) += snd-hda-cirrus-scodec.o
+obj-$(CONFIG_SND_HDA_CIRRUS_SCODEC_KUNIT_TEST) += snd-hda-cirrus-scodec-test.o
 obj-$(CONFIG_SND_HDA_SCODEC_CS35L41) += snd-hda-scodec-cs35l41.o
 obj-$(CONFIG_SND_HDA_SCODEC_CS35L41_I2C) += snd-hda-scodec-cs35l41-i2c.o
 obj-$(CONFIG_SND_HDA_SCODEC_CS35L41_SPI) += snd-hda-scodec-cs35l41-spi.o

sound/pci/hda/cs35l56_hda.c

@@ -1035,6 +1035,16 @@ const struct dev_pm_ops cs35l56_hda_pm_ops = {
 };
 EXPORT_SYMBOL_NS_GPL(cs35l56_hda_pm_ops, SND_HDA_SCODEC_CS35L56);
 
+#if IS_ENABLED(CONFIG_SND_HDA_SCODEC_CS35L56_KUNIT_TEST)
+/* Hooks to export static function to KUnit test */
+
+int cs35l56_hda_test_hook_get_speaker_id(struct device *dev, int amp_index, int num_amps)
+{
+	return cs35l56_hda_get_speaker_id(dev, amp_index, num_amps);
+}
+EXPORT_SYMBOL_NS_GPL(cs35l56_hda_test_hook_get_speaker_id, SND_HDA_SCODEC_CS35L56);
+#endif
+
 MODULE_DESCRIPTION("CS35L56 HDA Driver");
 MODULE_IMPORT_NS(SND_HDA_CIRRUS_SCODEC);
 MODULE_IMPORT_NS(SND_HDA_CS_DSP_CONTROLS);