ALSA: compress_offload: Add SNDRV_COMPRESS_AVAIL64 ioctl

The previous patch introduced a 64-bit timestamp ioctl
(SNDRV_COMPRESS_TSTAMP64). To provide a consistent API, this patch
adds a corresponding 64-bit version of the SNDRV_COMPRESS_AVAIL ioctl.

A new struct snd_compr_avail64 is added to the UAPI, which includes
the 64-bit timestamp. The existing ioctl implementation is refactored
to handle both the 32-bit and 64-bit variants.

Reviewed-by: Miller Liang <[e-mail]>
Tested-by: Joris Verhaegen <[e-mail]>
Signed-off-by: Joris Verhaegen <[e-mail]>
Acked-by: Vinod Koul <[e-mail]>
Reviewed-by: Charles Keepax <[e-mail]>
Signed-off-by: Takashi Iwai <[e-mail]>
Link: https://patch.msgid.link/[e-mail]

include/uapi/sound/compress_offload.h

···
 	struct snd_compr_tstamp tstamp;
 } __attribute__((packed, aligned(4)));
 
+/**
+ * struct snd_compr_avail64 - avail descriptor with tstamp in 64 bit format
+ * @avail: Number of bytes available in ring buffer for writing/reading
+ * @tstamp: timestamp information
+ */
+struct snd_compr_avail64 {
+	__u64 avail;
+	struct snd_compr_tstamp64 tstamp;
+} __attribute__((packed, aligned(4)));
+
 enum snd_compr_direction {
 	SND_COMPRESS_PLAYBACK = 0,
 	SND_COMPRESS_CAPTURE,
···
 #define SNDRV_COMPRESS_TSTAMP		_IOR('C', 0x20, struct snd_compr_tstamp)
 #define SNDRV_COMPRESS_AVAIL		_IOR('C', 0x21, struct snd_compr_avail)
 #define SNDRV_COMPRESS_TSTAMP64		_IOR('C', 0x22, struct snd_compr_tstamp64)
+#define SNDRV_COMPRESS_AVAIL64		_IOR('C', 0x23, struct snd_compr_avail64)
 #define SNDRV_COMPRESS_PAUSE		_IO('C', 0x30)
 #define SNDRV_COMPRESS_RESUME		_IO('C', 0x31)
 #define SNDRV_COMPRESS_START		_IO('C', 0x32)

sound/core/compress_offload.c

···
 }
 
 static size_t snd_compr_calc_avail(struct snd_compr_stream *stream,
-		struct snd_compr_avail *avail)
+				   struct snd_compr_avail64 *avail)
 {
-	struct snd_compr_tstamp64 tstamp64 = { 0 };
-
 	memset(avail, 0, sizeof(*avail));
-	snd_compr_update_tstamp(stream, &tstamp64);
-	snd_compr_tstamp32_from_64(&avail->tstamp, &tstamp64);
+	snd_compr_update_tstamp(stream, &avail->tstamp);
 	/* Still need to return avail even if tstamp can't be filled in */
 
 	if (stream->runtime->total_bytes_available == 0 &&
···
 	if (stream->direction == SND_COMPRESS_PLAYBACK)
 		avail->avail = stream->runtime->buffer_size - avail->avail;
 
-	pr_debug("ret avail as %llu\n", avail->avail);
+	pr_debug("ret avail as %zu\n", (size_t)avail->avail);
 	return avail->avail;
 }
 
 static inline size_t snd_compr_get_avail(struct snd_compr_stream *stream)
 {
-	struct snd_compr_avail avail;
+	struct snd_compr_avail64 avail;
 
 	return snd_compr_calc_avail(stream, &avail);
 }
 
-static int
-snd_compr_ioctl_avail(struct snd_compr_stream *stream, unsigned long arg)
+static void snd_compr_avail32_from_64(struct snd_compr_avail *avail32,
+				      const struct snd_compr_avail64 *avail64)
 {
-	struct snd_compr_avail ioctl_avail;
+	avail32->avail = avail64->avail;
+	snd_compr_tstamp32_from_64(&avail32->tstamp, &avail64->tstamp);
+}
+
+static int snd_compr_ioctl_avail(struct snd_compr_stream *stream,
+				 unsigned long arg, bool is_32bit)
+{
+	struct snd_compr_avail64 ioctl_avail64;
+	struct snd_compr_avail ioctl_avail32;
 	size_t avail;
+	const void *copy_from = &ioctl_avail64;
+	size_t copy_size = sizeof(ioctl_avail64);
 
 	if (stream->direction == SND_COMPRESS_ACCEL)
 		return -EBADFD;
 
-	avail = snd_compr_calc_avail(stream, &ioctl_avail);
-	ioctl_avail.avail = avail;
+	avail = snd_compr_calc_avail(stream, &ioctl_avail64);
+	ioctl_avail64.avail = avail;
+	if (is_32bit) {
+		snd_compr_avail32_from_64(&ioctl_avail32, &ioctl_avail64);
+		copy_from = &ioctl_avail32;
+		copy_size = sizeof(ioctl_avail32);
+	}
 
 	switch (stream->runtime->state) {
 	case SNDRV_PCM_STATE_OPEN:
···
 		break;
 	}
 
-	if (copy_to_user((__u64 __user *)arg,
-				&ioctl_avail, sizeof(ioctl_avail)))
+	if (copy_to_user((__u64 __user *)arg, copy_from, copy_size))
 		return -EFAULT;
 	return 0;
 }
···
 	case SNDRV_COMPRESS_TSTAMP64:
 		return snd_compr_tstamp(stream, arg, false);
 	case SNDRV_COMPRESS_AVAIL:
-		return snd_compr_ioctl_avail(stream, arg);
+		return snd_compr_ioctl_avail(stream, arg, true);
+	case SNDRV_COMPRESS_AVAIL64:
+		return snd_compr_ioctl_avail(stream, arg, false);
 	case SNDRV_COMPRESS_PAUSE:
 		return snd_compr_pause(stream);
 	case SNDRV_COMPRESS_RESUME: