ALSA: emu8000: Convert to generic PCM copy ops

This patch converts the SB Emu8000 driver code to use the new unified
PCM copy callback.  The conversion is a bit complicated because of
many open code in emu8000_pcm.c.  GET_VAL() and LOOP_WRITE() macros
were rewritten / simplified with copy_from_iter().  As
copy_from_iter() updates the internal offset value, we can drop the
corresponding part, too.

Link: https://lore.kernel.org/r/20230815190136.8987-7-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/isa/sb/emu8000_pcm.c

@@ -409,39 +409,25 @@ do { \
 		return -EAGAIN;\
 } while (0)
 
-enum {
-	COPY_USER, COPY_KERNEL, FILL_SILENCE,
-};
-
-#define GET_VAL(sval, buf, mode)					\
+#define GET_VAL(sval, iter)						\
 	do {								\
-		switch (mode) {						\
-		case FILL_SILENCE:					\
+		if (!iter)						\
 			sval = 0;					\
-			break;						\
-		case COPY_KERNEL:					\
-			sval = *buf++;					\
-			break;						\
-		default:						\
-			if (get_user(sval, (unsigned short __user *)buf)) \
-				return -EFAULT;				\
-			buf++;						\
-			break;						\
-		}							\
+		else if (copy_from_iter(&sval, 2, iter) != 2)		\
+			return -EFAULT;					\
 	} while (0)
 
 #ifdef USE_NONINTERLEAVE
 
-#define LOOP_WRITE(rec, offset, _buf, count, mode)		\
+#define LOOP_WRITE(rec, offset, iter, count)			\
 	do {							\
 		struct snd_emu8000 *emu = (rec)->emu;		\
-		unsigned short *buf = (__force unsigned short *)(_buf); \
 		snd_emu8000_write_wait(emu, 1);			\
 		EMU8000_SMALW_WRITE(emu, offset);		\
 		while (count > 0) {				\
 			unsigned short sval;			\
 			CHECK_SCHEDULER();			\
-			GET_VAL(sval, buf, mode);		\
+			GET_VAL(sval, iter);			\
 			EMU8000_SMLD_WRITE(emu, sval);		\
 			count--;				\
 		}						\
@@ -450,27 +436,14 @@ enum {
 /* copy one channel block */
 static int emu8k_pcm_copy(struct snd_pcm_substream *subs,
 			  int voice, unsigned long pos,
-			  void __user *src, unsigned long count)
+			  struct iov_iter *src, unsigned long count)
 {
 	struct snd_emu8k_pcm *rec = subs->runtime->private_data;
 
 	/* convert to word unit */
 	pos = (pos << 1) + rec->loop_start[voice];
 	count <<= 1;
-	LOOP_WRITE(rec, pos, src, count, COPY_USER);
-	return 0;
-}
-
-static int emu8k_pcm_copy_kernel(struct snd_pcm_substream *subs,
-				 int voice, unsigned long pos,
-				 void *src, unsigned long count)
-{
-	struct snd_emu8k_pcm *rec = subs->runtime->private_data;
-
-	/* convert to word unit */
-	pos = (pos << 1) + rec->loop_start[voice];
-	count <<= 1;
-	LOOP_WRITE(rec, pos, src, count, COPY_KERNEL);
+	LOOP_WRITE(rec, pos, src, count);
 	return 0;
 }
 
@@ -483,16 +456,15 @@ static int emu8k_pcm_silence(struct snd_pcm_substream *subs,
 	/* convert to word unit */
 	pos = (pos << 1) + rec->loop_start[voice];
 	count <<= 1;
-	LOOP_WRITE(rec, pos, NULL, count, FILL_SILENCE);
+	LOOP_WRITE(rec, pos, USER_SOCKPTR(NULL), count);
 	return 0;
 }
 
 #else /* interleave */
 
-#define LOOP_WRITE(rec, pos, _buf, count, mode)				\
+#define LOOP_WRITE(rec, pos, iter, count)				\
 	do {								\
 		struct snd_emu8000 *emu = rec->emu;			\
-		unsigned short *buf = (__force unsigned short *)(_buf);	\
 		snd_emu8000_write_wait(emu, 1);				\
 		EMU8000_SMALW_WRITE(emu, pos + rec->loop_start[0]);	\
 		if (rec->voices > 1)					\
@@ -500,11 +472,11 @@ static int emu8k_pcm_silence(struct snd_pcm_substream *subs,
 		while (count > 0) {					\
 			unsigned short sval;				\
 			CHECK_SCHEDULER();				\
-			GET_VAL(sval, buf, mode);			\
+			GET_VAL(sval, iter);				\
 			EMU8000_SMLD_WRITE(emu, sval);			\
 			if (rec->voices > 1) {				\
 				CHECK_SCHEDULER();			\
-				GET_VAL(sval, buf, mode);		\
+				GET_VAL(sval, iter);			\
 				EMU8000_SMRD_WRITE(emu, sval);		\
 			}						\
 			count--;					\
@@ -518,27 +490,14 @@ static int emu8k_pcm_silence(struct snd_pcm_substream *subs,
  */
 static int emu8k_pcm_copy(struct snd_pcm_substream *subs,
 			  int voice, unsigned long pos,
-			  void __user *src, unsigned long count)
-{
-	struct snd_emu8k_pcm *rec = subs->runtime->private_data;
-
-	/* convert to frames */
-	pos = bytes_to_frames(subs->runtime, pos);
-	count = bytes_to_frames(subs->runtime, count);
-	LOOP_WRITE(rec, pos, src, count, COPY_USER);
-	return 0;
-}
-
-static int emu8k_pcm_copy_kernel(struct snd_pcm_substream *subs,
-				 int voice, unsigned long pos,
-				 void *src, unsigned long count)
+			  struct iov_iter *src, unsigned long count)
 {
 	struct snd_emu8k_pcm *rec = subs->runtime->private_data;
 
 	/* convert to frames */
 	pos = bytes_to_frames(subs->runtime, pos);
 	count = bytes_to_frames(subs->runtime, count);
-	LOOP_WRITE(rec, pos, src, count, COPY_KERNEL);
+	LOOP_WRITE(rec, pos, src, count);
 	return 0;
 }
 
@@ -550,7 +509,7 @@ static int emu8k_pcm_silence(struct snd_pcm_substream *subs,
 	/* convert to frames */
 	pos = bytes_to_frames(subs->runtime, pos);
 	count = bytes_to_frames(subs->runtime, count);
-	LOOP_WRITE(rec, pos, NULL, count, FILL_SILENCE);
+	LOOP_WRITE(rec, pos, NULL, count);
 	return 0;
 }
 #endif
@@ -666,8 +625,7 @@ static const struct snd_pcm_ops emu8k_pcm_ops = {
 	.prepare =	emu8k_pcm_prepare,
 	.trigger =	emu8k_pcm_trigger,
 	.pointer =	emu8k_pcm_pointer,
-	.copy_user =	emu8k_pcm_copy,
-	.copy_kernel =	emu8k_pcm_copy_kernel,
+	.copy =		emu8k_pcm_copy,
 	.fill_silence =	emu8k_pcm_silence,
 };