ASoC: SOF: ipc4-pcm: add delay function support

The delay function is used to calculate the difference
between hw_ptr and dai dma position. I2S, DMIC and SDW will
use dai dma position in shared SRAM window to calculate the
delay. HDaudio will retrieve dai dma position from host mmio memory
space since it doesn't support LLP counter reported by firmware.

In two cases dai dma position is inaccurate for delay calculation
(1) dai pipeline is started before host pipeline
(2) multiple streams mixed into one. Each stream has the same dai
    dma position
Firmware calculates correct stream_start_offset for all cases including
above two. Driver subtracts stream_start_offset from dai dma position to
get accurate one.
Signed-off-by: Rander Wang <rander.wang@intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/20230202132954.26773-10-peter.ujfalusi@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/ipc4-pcm.c

@@ -10,6 +10,7 @@
 #include <sound/sof/ipc4/header.h>
 #include "sof-audio.h"
 #include "sof-priv.h"
+#include "ops.h"
 #include "ipc4-priv.h"
 #include "ipc4-topology.h"
 #include "ipc4-fw-reg.h"
@@ -556,6 +557,113 @@ static int sof_ipc4_pcm_hw_params(struct snd_soc_component *component,
 	return 0;
 }
 
+static int sof_ipc4_get_stream_start_offset(struct snd_sof_dev *sdev,
+					    struct snd_pcm_substream *substream,
+					    struct snd_sof_pcm_stream *stream,
+					    struct sof_ipc4_timestamp_info *time_info)
+{
+	struct sof_ipc4_copier *host_copier = time_info->host_copier;
+	struct sof_ipc4_copier *dai_copier = time_info->dai_copier;
+	struct sof_ipc4_pipeline_registers ppl_reg;
+	u64 stream_start_position;
+	u32 dai_sample_size;
+	u32 ch, node_index;
+	u32 offset;
+
+	if (!host_copier || !dai_copier)
+		return -EINVAL;
+
+	if (host_copier->data.gtw_cfg.node_id == SOF_IPC4_INVALID_NODE_ID)
+		return -EINVAL;
+
+	node_index = SOF_IPC4_NODE_INDEX(host_copier->data.gtw_cfg.node_id);
+	offset = offsetof(struct sof_ipc4_fw_registers, pipeline_regs) + node_index * sizeof(ppl_reg);
+	sof_mailbox_read(sdev, sdev->fw_info_box.offset + offset, &ppl_reg, sizeof(ppl_reg));
+	if (ppl_reg.stream_start_offset == SOF_IPC4_INVALID_STREAM_POSITION)
+		return -EINVAL;
+
+	stream_start_position = ppl_reg.stream_start_offset;
+	ch = dai_copier->data.out_format.fmt_cfg;
+	ch = SOF_IPC4_AUDIO_FORMAT_CFG_CHANNELS_COUNT(ch);
+	dai_sample_size = (dai_copier->data.out_format.bit_depth >> 3) * ch;
+	/* convert offset to sample count */
+	do_div(stream_start_position, dai_sample_size);
+	time_info->stream_start_offset = stream_start_position;
+
+	return 0;
+}
+
+static snd_pcm_sframes_t sof_ipc4_pcm_delay(struct snd_soc_component *component,
+					    struct snd_pcm_substream *substream)
+{
+	struct snd_sof_dev *sdev = snd_soc_component_get_drvdata(component);
+	struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);
+	struct sof_ipc4_timestamp_info *time_info;
+	struct sof_ipc4_llp_reading_slot llp;
+	snd_pcm_uframes_t head_ptr, tail_ptr;
+	struct snd_sof_pcm_stream *stream;
+	struct snd_sof_pcm *spcm;
+	u64 tmp_ptr;
+	int ret;
+
+	spcm = snd_sof_find_spcm_dai(component, rtd);
+	if (!spcm)
+		return 0;
+
+	stream = &spcm->stream[substream->stream];
+	time_info = stream->private;
+	if (!time_info)
+		return 0;
+
+	/*
+	 * stream_start_offset is updated to memory window by FW based on
+	 * pipeline statistics and it may be invalid if host query happens before
+	 * the statistics is complete. And it will not change after the first initiailization.
+	 */
+	if (time_info->stream_start_offset == SOF_IPC4_INVALID_STREAM_POSITION) {
+		ret = sof_ipc4_get_stream_start_offset(sdev, substream, stream, time_info);
+		if (ret < 0)
+			return 0;
+	}
+
+	/*
+	 * HDaudio links don't support the LLP counter reported by firmware
+	 * the link position is read directly from hardware registers.
+	 */
+	if (!time_info->llp_offset) {
+		tmp_ptr = snd_sof_pcm_get_stream_position(sdev, component, substream);
+		if (!tmp_ptr)
+			return 0;
+	} else {
+		sof_mailbox_read(sdev, time_info->llp_offset, &llp, sizeof(llp));
+		tmp_ptr = ((u64)llp.reading.llp_u << 32) | llp.reading.llp_l;
+	}
+
+	/* In two cases dai dma position is not accurate
+	 * (1) dai pipeline is started before host pipeline
+	 * (2) multiple streams mixed into one. Each stream has the same dai dma position
+	 *
+	 * Firmware calculates correct stream_start_offset for all cases including above two.
+	 * Driver subtracts stream_start_offset from dai dma position to get accurate one
+	 */
+	tmp_ptr -= time_info->stream_start_offset;
+
+	/* Calculate the delay taking into account that both pointer can wrap */
+	div64_u64_rem(tmp_ptr, substream->runtime->boundary, &tmp_ptr);
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+		head_ptr = substream->runtime->status->hw_ptr;
+		tail_ptr = tmp_ptr;
+	} else {
+		head_ptr = tmp_ptr;
+		tail_ptr = substream->runtime->status->hw_ptr;
+	}
+
+	if (head_ptr < tail_ptr)
+		return substream->runtime->boundary - tail_ptr + head_ptr;
+
+	return head_ptr - tail_ptr;
+}
+
 const struct sof_ipc_pcm_ops ipc4_pcm_ops = {
 	.hw_params = sof_ipc4_pcm_hw_params,
 	.trigger = sof_ipc4_pcm_trigger,
@@ -563,4 +671,5 @@ const struct sof_ipc_pcm_ops ipc4_pcm_ops = {
 	.dai_link_fixup = sof_ipc4_pcm_dai_link_fixup,
 	.pcm_setup = sof_ipc4_pcm_setup,
 	.pcm_free = sof_ipc4_pcm_free,
+	.delay = sof_ipc4_pcm_delay
 };