[PATCH 1/7] soundwire: intel: Define stubs when library is disabled

[Cezary Rojewski <cezary.rojewski@intel.com>]

The library defines no stubs when it is disabled so the actual users
have to do it locally to allow the code to compilte or, guard the code
that does interact with soundwire with #if(s). Define simple wrappers to
make the life of soundwire-code users easier.

The change allows for a driver to build against SOUNDWIRE_INTEL=n whilst
still calling the stubs in its common code without compilation failing.
The driver needs not to flank its soundwire-code with #if(s) either.

Not all sdw_intel_xxx()s are part of drivers/soundwire. Some definitions
are located within sound/hda/core instead. With the wrappers done,
update Kconfig for sound/hda/core as currently the ACPI-related function
are compiled regardless if SOUNDWIRE_INTEL is selected or not. By being
dependent on SOUNDWIRE_INTEL those functions are compiled only if the
SoundWire was actually requested.

Cc: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
---
 include/linux/soundwire/sdw_intel.h | 34 +++++++++++++++++++++++++++++
 sound/hda/core/Kconfig              |  2 +-
 sound/hda/core/Makefile             |  3 +++
 3 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/include/linux/soundwire/sdw_intel.h b/include/linux/soundwire/sdw_intel.h
index 9710f2dc04e2..83021cc0f5b8 100644
--- a/include/linux/soundwire/sdw_intel.h
+++ b/include/linux/soundwire/sdw_intel.h
@@ -358,6 +358,8 @@ struct sdw_intel_res {
 	struct mutex *eml_lock;
 };
 
+#if IS_ENABLED(CONFIG_SOUNDWIRE_INTEL)
+
 /*
  * On Intel platforms, the SoundWire IP has dependencies on power
  * rails shared with the DSP, and the initialization steps are split
@@ -384,6 +386,38 @@ void sdw_intel_exit(struct sdw_intel_ctx *ctx);
 
 irqreturn_t sdw_intel_thread(int irq, void *dev_id);
 
+#else
+
+static inline int sdw_intel_acpi_scan(acpi_handle parent_handle, struct sdw_intel_acpi_info *info)
+{
+	return 0;
+}
+
+static inline void sdw_intel_process_wakeen_event(struct sdw_intel_ctx *ctx)
+{
+}
+
+static inline struct sdw_intel_ctx *sdw_intel_probe(struct sdw_intel_res *res)
+{
+	return NULL;
+}
+
+static inline int sdw_intel_startup(struct sdw_intel_ctx *ctx)
+{
+	return 0;
+}
+
+static inline void sdw_intel_exit(struct sdw_intel_ctx *ctx)
+{
+}
+
+static inline irqreturn_t sdw_intel_thread(int irq, void *dev_id)
+{
+	return 0;
+}
+
+#endif
+
 #define SDW_INTEL_QUIRK_MASK_BUS_DISABLE      BIT(1)
 
 struct sdw_intel;
diff --git a/sound/hda/core/Kconfig b/sound/hda/core/Kconfig
index bfdcf6384c52..f91053dd9f58 100644
--- a/sound/hda/core/Kconfig
+++ b/sound/hda/core/Kconfig
@@ -29,7 +29,7 @@ config SND_INTEL_DSP_CONFIG
 	tristate
 	select ACPI_NHLT if ACPI
 	select SND_INTEL_NHLT if ACPI
-	select SND_INTEL_SOUNDWIRE_ACPI if ACPI
+	select SND_INTEL_SOUNDWIRE_ACPI if SOUNDWIRE_INTEL
 	# this config should be selected only for Intel DSP platforms.
 	# A fallback is provided so that the code compiles in all cases.
 
diff --git a/sound/hda/core/Makefile b/sound/hda/core/Makefile
index 89cb46143050..28032ac7bc61 100644
--- a/sound/hda/core/Makefile
+++ b/sound/hda/core/Makefile
@@ -18,5 +18,8 @@ snd-intel-dspcfg-y := intel-dsp-config.o
 snd-intel-dspcfg-$(CONFIG_SND_INTEL_NHLT) += intel-nhlt.o
 obj-$(CONFIG_SND_INTEL_DSP_CONFIG) += snd-intel-dspcfg.o
 
+ifneq ($(CONFIG_SND_INTEL_SOUNDWIRE_ACPI),)
 snd-intel-sdw-acpi-y := intel-sdw-acpi.o
+endif
+
 obj-$(CONFIG_SND_INTEL_SOUNDWIRE_ACPI) += snd-intel-sdw-acpi.o
-- 
2.34.1