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

2 files changed, 32 insertions, 20 deletions

diff --git a/sound/soc/qcom/qdsp6/q6apm-dai.c b/sound/soc/qcom/qdsp6/q6apm-dai.c
index 2cd522108221..09da26f712a6 100644
--- a/sound/soc/qcom/qdsp6/q6apm-dai.c
+++ b/sound/soc/qcom/qdsp6/q6apm-dai.c
@@ -11,6 +11,7 @@
 #include <sound/soc-dapm.h>
 #include <linux/spinlock.h>
 #include <sound/pcm.h>
+#include <asm/div64.h>
 #include <asm/dma.h>
 #include <linux/dma-mapping.h>
 #include <sound/pcm_params.h>
@@ -65,9 +66,9 @@ struct q6apm_dai_rtd {
 	unsigned int pcm_size;
 	unsigned int pcm_count;
 	unsigned int periods;
-	unsigned int bytes_sent;
-	unsigned int bytes_received;
-	unsigned int copied_total;
+	uint64_t bytes_sent;
+	uint64_t bytes_received;
+	uint64_t copied_total;
 	uint16_t bits_per_sample;
 	snd_pcm_uframes_t queue_ptr;
 	bool next_track;
@@ -575,15 +576,17 @@ static int q6apm_dai_compr_get_codec_caps(struct snd_soc_component *component,
 
 static int q6apm_dai_compr_pointer(struct snd_soc_component *component,
 				   struct snd_compr_stream *stream,
-				   struct snd_compr_tstamp *tstamp)
+				   struct snd_compr_tstamp64 *tstamp)
 {
 	struct snd_compr_runtime *runtime = stream->runtime;
 	struct q6apm_dai_rtd *prtd = runtime->private_data;
 	unsigned long flags;
+	uint64_t temp_copied_total;
 
 	spin_lock_irqsave(&prtd->lock, flags);
 	tstamp->copied_total = prtd->copied_total;
-	tstamp->byte_offset = prtd->copied_total % prtd->pcm_size;
+	temp_copied_total = tstamp->copied_total;
+	tstamp->byte_offset = do_div(temp_copied_total, prtd->pcm_size);
 	spin_unlock_irqrestore(&prtd->lock, flags);
 
 	return 0;
@@ -760,21 +763,24 @@ static int q6apm_compr_copy(struct snd_soc_component *component,
 	size_t copy;
 	u32 wflags = 0;
 	u32 app_pointer;
-	u32 bytes_received;
+	uint64_t bytes_received;
+	uint64_t temp_bytes_received;
 	uint32_t bytes_to_write;
-	int avail, bytes_in_flight = 0;
+	uint64_t avail, bytes_in_flight = 0;
 
 	bytes_received = prtd->bytes_received;
+	temp_bytes_received = bytes_received;
 
 	/**
 	 * Make sure that next track data pointer is aligned at 32 bit boundary
 	 * This is a Mandatory requirement from DSP data buffers alignment
 	 */
-	if (prtd->next_track)
+	if (prtd->next_track) {
 		bytes_received = ALIGN(prtd->bytes_received, prtd->pcm_count);
+		temp_bytes_received = bytes_received;
+	}
 
-	app_pointer = bytes_received/prtd->pcm_size;
-	app_pointer = bytes_received -  (app_pointer * prtd->pcm_size);
+	app_pointer = do_div(temp_bytes_received, prtd->pcm_size);
 	dstn = prtd->dma_buffer.area + app_pointer;
 
 	if (count < prtd->pcm_size - app_pointer) {
diff --git a/sound/soc/qcom/qdsp6/q6asm-dai.c b/sound/soc/qcom/qdsp6/q6asm-dai.c
index a400c9a31fea..b616ce316d2f 100644
--- a/sound/soc/qcom/qdsp6/q6asm-dai.c
+++ b/sound/soc/qcom/qdsp6/q6asm-dai.c
@@ -14,6 +14,7 @@
 #include <sound/pcm.h>
 #include <linux/spinlock.h>
 #include <sound/compress_driver.h>
+#include <asm/div64.h>
 #include <asm/dma.h>
 #include <linux/dma-mapping.h>
 #include <sound/pcm_params.h>
@@ -59,9 +60,9 @@ struct q6asm_dai_rtd {
 	unsigned int pcm_count;
 	unsigned int pcm_irq_pos;       /* IRQ position */
 	unsigned int periods;
-	unsigned int bytes_sent;
-	unsigned int bytes_received;
-	unsigned int copied_total;
+	uint64_t bytes_sent;
+	uint64_t bytes_received;
+	uint64_t copied_total;
 	uint16_t bits_per_sample;
 	uint16_t source; /* Encoding source bit mask */
 	struct audio_client *audio_client;
@@ -1026,16 +1027,18 @@ static int q6asm_dai_compr_trigger(struct snd_soc_component *component,
 
 static int q6asm_dai_compr_pointer(struct snd_soc_component *component,
 				   struct snd_compr_stream *stream,
-				   struct snd_compr_tstamp *tstamp)
+				   struct snd_compr_tstamp64 *tstamp)
 {
 	struct snd_compr_runtime *runtime = stream->runtime;
 	struct q6asm_dai_rtd *prtd = runtime->private_data;
 	unsigned long flags;
+	uint64_t temp_copied_total;
 
 	spin_lock_irqsave(&prtd->lock, flags);
 
 	tstamp->copied_total = prtd->copied_total;
-	tstamp->byte_offset = prtd->copied_total % prtd->pcm_size;
+	temp_copied_total = tstamp->copied_total;
+	tstamp->byte_offset = do_div(temp_copied_total, prtd->pcm_size);
 
 	spin_unlock_irqrestore(&prtd->lock, flags);
 
@@ -1050,23 +1053,26 @@ static int q6asm_compr_copy(struct snd_soc_component *component,
 	struct q6asm_dai_rtd *prtd = runtime->private_data;
 	unsigned long flags;
 	u32 wflags = 0;
-	int avail, bytes_in_flight = 0;
+	uint64_t avail, bytes_in_flight = 0;
 	void *dstn;
 	size_t copy;
 	u32 app_pointer;
-	u32 bytes_received;
+	uint64_t bytes_received;
+	uint64_t temp_bytes_received;
 
 	bytes_received = prtd->bytes_received;
+	temp_bytes_received = bytes_received;
 
 	/**
 	 * Make sure that next track data pointer is aligned at 32 bit boundary
 	 * This is a Mandatory requirement from DSP data buffers alignment
 	 */
-	if (prtd->next_track)
+	if (prtd->next_track) {
 		bytes_received = ALIGN(prtd->bytes_received, prtd->pcm_count);
+		temp_bytes_received = bytes_received;
+	}
 
-	app_pointer = bytes_received/prtd->pcm_size;
-	app_pointer = bytes_received -  (app_pointer * prtd->pcm_size);
+	app_pointer = do_div(temp_bytes_received, prtd->pcm_size);
 	dstn = prtd->dma_buffer.area + app_pointer;
 
 	if (count < prtd->pcm_size - app_pointer) {