ALSA: compress_offload: Add 64-bit safe timestamp infrastructure

The copied_total field in struct snd_compr_tstamp is a 32-bit
value that can overflow on long-running high-bitrate streams,
leading to incorrect calculations for buffer availablility.

This patch adds a 64-bit safe timestamping mechanism.
A new UAPI struct, snd_compr_tstamp64, is added which uses 64-bit
types for byte counters. The relevant ops structures across the
ASoC and core compress code are updated to use this new struct.
ASoC drivers are updated to use u64 counters.

Internal timestamps being u64 now, a compatibility function is added
to convert the 64-bit timestamp back to the 32-bit format for legacy
ioctl callers.

Reviewed-by: Miller Liang <millerliang@google.com>
Tested-by: Joris Verhaegen <verhaegen@google.com>
Signed-off-by: Joris Verhaegen <verhaegen@google.com>
Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@oss.qualcomm.com>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20250905091301.2711705-2-verhaegen@google.com

4 files changed, 14 insertions, 11 deletions

diff --git a/sound/soc/intel/atom/sst-mfld-platform-compress.c b/sound/soc/intel/atom/sst-mfld-platform-compress.c
index 89c9c5ad6b21..9dfb0a814b94 100644
--- a/sound/soc/intel/atom/sst-mfld-platform-compress.c
+++ b/sound/soc/intel/atom/sst-mfld-platform-compress.c
@@ -18,6 +18,7 @@
 #include <sound/pcm_params.h>
 #include <sound/soc.h>
 #include <sound/compress_driver.h>
+#include <asm/div64.h>
 #include "sst-mfld-platform.h"
 
 /* compress stream operations */
@@ -202,15 +203,16 @@ static int sst_platform_compr_trigger(struct snd_soc_component *component,
 
 static int sst_platform_compr_pointer(struct snd_soc_component *component,
 				      struct snd_compr_stream *cstream,
-				      struct snd_compr_tstamp *tstamp)
+				      struct snd_compr_tstamp64 *tstamp)
 {
 	struct sst_runtime_stream *stream;
+	u64 temp_copied_total = tstamp->copied_total;
 
-	stream  = cstream->runtime->private_data;
+	stream = cstream->runtime->private_data;
 	stream->compr_ops->tstamp(sst->dev, stream->id, tstamp);
-	tstamp->byte_offset = tstamp->copied_total %
-				 (u32)cstream->runtime->buffer_size;
-	pr_debug("calc bytes offset/copied bytes as %d\n", tstamp->byte_offset);
+	tstamp->byte_offset =
+		do_div(temp_copied_total, cstream->runtime->buffer_size);
+	pr_debug("calc bytes offset/copied bytes as %u\n", tstamp->byte_offset);
 	return 0;
 }
 
diff --git a/sound/soc/intel/atom/sst-mfld-platform.h b/sound/soc/intel/atom/sst-mfld-platform.h
index 8b5777d3229a..a0e33f7f01c5 100644
--- a/sound/soc/intel/atom/sst-mfld-platform.h
+++ b/sound/soc/intel/atom/sst-mfld-platform.h
@@ -105,7 +105,7 @@ struct compress_sst_ops {
 	int (*stream_pause_release)(struct device *dev,	unsigned int str_id);
 
 	int (*tstamp)(struct device *dev, unsigned int str_id,
-			struct snd_compr_tstamp *tstamp);
+		      struct snd_compr_tstamp64 *tstamp);
 	int (*ack)(struct device *dev, unsigned int str_id,
 			unsigned long bytes);
 	int (*close)(struct device *dev, unsigned int str_id);
diff --git a/sound/soc/intel/atom/sst/sst_drv_interface.c b/sound/soc/intel/atom/sst/sst_drv_interface.c
index 8bb27f86eb65..2646c4632ca1 100644
--- a/sound/soc/intel/atom/sst/sst_drv_interface.c
+++ b/sound/soc/intel/atom/sst/sst_drv_interface.c
@@ -326,7 +326,7 @@ static int sst_cdev_stream_partial_drain(struct device *dev,
 }
 
 static int sst_cdev_tstamp(struct device *dev, unsigned int str_id,
-		struct snd_compr_tstamp *tstamp)
+			   struct snd_compr_tstamp64 *tstamp)
 {
 	struct snd_sst_tstamp fw_tstamp = {0,};
 	struct stream_info *stream;
@@ -349,10 +349,11 @@ static int sst_cdev_tstamp(struct device *dev, unsigned int str_id,
 			(u64)stream->num_ch * SST_GET_BYTES_PER_SAMPLE(24));
 	tstamp->sampling_rate = fw_tstamp.sampling_frequency;
 
-	dev_dbg(dev, "PCM  = %u\n", tstamp->pcm_io_frames);
-	dev_dbg(dev, "Ptr Query on strid = %d  copied_total %d, decodec %d\n",
+	dev_dbg(dev, "PCM  = %llu\n", tstamp->pcm_io_frames);
+	dev_dbg(dev,
+		"Ptr Query on strid = %d  copied_total %llu, decodec %llu\n",
 		str_id, tstamp->copied_total, tstamp->pcm_frames);
-	dev_dbg(dev, "rendered %d\n", tstamp->pcm_io_frames);
+	dev_dbg(dev, "rendered %llu\n", tstamp->pcm_io_frames);
 
 	return 0;
 }
diff --git a/sound/soc/intel/avs/probes.c b/sound/soc/intel/avs/probes.c
index a42736b9aa55..b5b4b0754b71 100644
--- a/sound/soc/intel/avs/probes.c
+++ b/sound/soc/intel/avs/probes.c
@@ -213,7 +213,7 @@ static int avs_probe_compr_trigger(struct snd_compr_stream *cstream, int cmd,
 }
 
 static int avs_probe_compr_pointer(struct snd_compr_stream *cstream,
-				   struct snd_compr_tstamp *tstamp, struct snd_soc_dai *dai)
+				   struct snd_compr_tstamp64 *tstamp, struct snd_soc_dai *dai)
 {
 	struct hdac_ext_stream *host_stream = avs_compr_get_host_stream(cstream);
 	struct snd_soc_pcm_stream *pstream;