ASoC: SOF: Intel: hda: Implement get_stream_position (Linear Link Position)

When the Linear Link Position is not available in firmware SRAM window we
use the host accessible position registers to read it.
The address of the PPLCLLPL/U registers depend on the number of streams
(playback+capture).
At probe time the pplc_addr is calculated for each stream and we can use
it to read the LLP without the need of address re-calculation.

Set the get_stream_position callback in sof_hda_common_ops for all
platforms:
The callback is used for IPC4 delay calculations only but the register is
a generic HDA register, not tied to any specific IPC version.

Cc: stable@vger.kernel.org # 6.8
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://msgid.link/r/20240321130814.4412-5-peter.ujfalusi@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/intel/hda-common-ops.c

@@ -57,6 +57,8 @@ struct snd_sof_dsp_ops sof_hda_common_ops = {
 	.pcm_pointer	= hda_dsp_pcm_pointer,
 	.pcm_ack	= hda_dsp_pcm_ack,
 
+	.get_stream_position = hda_dsp_get_stream_llp,
+
 	/* firmware loading */
 	.load_firmware = snd_sof_load_firmware_raw,
 

sound/soc/sof/intel/hda-stream.c

@@ -1063,3 +1063,35 @@ snd_pcm_uframes_t hda_dsp_stream_get_position(struct hdac_stream *hstream,
 
 	return pos;
 }
+
+/**
+ * hda_dsp_get_stream_llp - Retrieve the LLP (Linear Link Position) of the stream
+ * @sdev: SOF device
+ * @component: ASoC component
+ * @substream: PCM substream
+ *
+ * Returns the raw Linear Link Position value
+ */
+u64 hda_dsp_get_stream_llp(struct snd_sof_dev *sdev,
+			   struct snd_soc_component *component,
+			   struct snd_pcm_substream *substream)
+{
+	struct hdac_stream *hstream = substream->runtime->private_data;
+	struct hdac_ext_stream *hext_stream = stream_to_hdac_ext_stream(hstream);
+	u32 llp_l, llp_u;
+
+	/*
+	 * The pplc_addr have been calculated during probe in
+	 * hda_dsp_stream_init():
+	 * pplc_addr = sdev->bar[HDA_DSP_PP_BAR] +
+	 *	       SOF_HDA_PPLC_BASE +
+	 *	       SOF_HDA_PPLC_MULTI * total_stream +
+	 *	       SOF_HDA_PPLC_INTERVAL * stream_index
+	 *
+	 * Use this pre-calculated address to avoid repeated re-calculation.
+	 */
+	llp_l = readl(hext_stream->pplc_addr + AZX_REG_PPLCLLPL);
+	llp_u = readl(hext_stream->pplc_addr + AZX_REG_PPLCLLPU);
+
+	return ((u64)llp_u << 32) | llp_l;
+}

sound/soc/sof/intel/hda.h

@@ -662,6 +662,9 @@ bool hda_dsp_check_stream_irq(struct snd_sof_dev *sdev);
 
 snd_pcm_uframes_t hda_dsp_stream_get_position(struct hdac_stream *hstream,
 					      int direction, bool can_sleep);
+u64 hda_dsp_get_stream_llp(struct snd_sof_dev *sdev,
+			   struct snd_soc_component *component,
+			   struct snd_pcm_substream *substream);
 
 struct hdac_ext_stream *
 	hda_dsp_stream_get(struct snd_sof_dev *sdev, int direction, u32 flags);