ASoC: SOF: ipc4: Add new message type: SOF_IPC4_GLB_LOAD_LIBRARY_PREPARE

On Intel platforms there is a strict order requirement for the DMA
programming:
DSP side configures the buffer and sets the GEN bit
Host side sets the RUN bit.

In order to follow this flow, a new global message type has been added to
prepare the DSP side of the DMA:

host sends LOAD_LIBRARY_PREPARE with the dma_id
DSP side sets its buffer and sets the GEN bit
Host sets the RUN bit
Host sends LOAD_LIBRARY with dma_id and lib_id
DSP receives the library data.

It is up to the platform code to use the new prepare stage message and how
to handle the reply to it from the firmware, which can indicate that the
message type is not supported/handled.
In this case the kernel should proceed to the LOAD_LIBRARY stage assuming
a single stage library loading:

host sends LOAD_LIBRARY_PREPARE with the dma_id
DSP replies that the message type is not supported/handled
Host acknowledges the return code and sets the RUN bit
Host sends LOAD_LIBRARY with dma_id and lib_id
DSP receives the library data.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Chao Song <chao.song@linux.intel.com>
Link: https://lore.kernel.org/r/20230915114018.1701-4-peter.ujfalusi@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

include/sound/sof/ipc4/header.h

@@ -106,12 +106,19 @@ enum sof_ipc4_global_msg {
 	SOF_IPC4_GLB_SAVE_PIPELINE,
 	SOF_IPC4_GLB_RESTORE_PIPELINE,
 
-	/* Loads library (using Code Load or HD/A Host Output DMA) */
+	/*
+	 * library loading
+	 *
+	 * Loads library (using Code Load or HD/A Host Output DMA)
+	 */
 	SOF_IPC4_GLB_LOAD_LIBRARY,
+	/*
+	 * Prepare the host DMA channel for library loading, must be followed by
+	 * a SOF_IPC4_GLB_LOAD_LIBRARY message as the library loading step
+	 */
+	SOF_IPC4_GLB_LOAD_LIBRARY_PREPARE,
 
-	/* 25: RESERVED - do not use */
-
-	SOF_IPC4_GLB_INTERNAL_MESSAGE = 26,
+	SOF_IPC4_GLB_INTERNAL_MESSAGE,
 
 	/* Notification (FW to SW driver) */
 	SOF_IPC4_GLB_NOTIFICATION,

sound/soc/sof/ipc4.c

@@ -157,6 +157,7 @@ static const char * const ipc4_dbg_glb_msg_type[] = {
 	DBG_IPC4_MSG_TYPE_ENTRY(GLB_SAVE_PIPELINE),
 	DBG_IPC4_MSG_TYPE_ENTRY(GLB_RESTORE_PIPELINE),
 	DBG_IPC4_MSG_TYPE_ENTRY(GLB_LOAD_LIBRARY),
+	DBG_IPC4_MSG_TYPE_ENTRY(GLB_LOAD_LIBRARY_PREPARE),
 	DBG_IPC4_MSG_TYPE_ENTRY(GLB_INTERNAL_MESSAGE),
 	DBG_IPC4_MSG_TYPE_ENTRY(GLB_NOTIFICATION),
 };