ALSA: es1938: Convert to generic PCM copy ops

This patch converts the es1938 driver code to use the new unified PCM
copy callback. It's a straightforward conversion from *_user() to
*_iter() variants in most parts.

Note that copy_from/to_iter() returns the copied bytes, hence the
error condition is adjusted accordingly.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Takashi Iwai <[e-mail]>

sound/pci/es1938.c

···
 
 static int snd_es1938_capture_copy(struct snd_pcm_substream *substream,
 				   int channel, unsigned long pos,
-				   void __user *dst, unsigned long count)
+				   struct iov_iter *dst, unsigned long count)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct es1938 *chip = snd_pcm_substream_chip(substream);
···
 	if (snd_BUG_ON(pos + count > chip->dma1_size))
 		return -EINVAL;
 	if (pos + count < chip->dma1_size) {
-		if (copy_to_user(dst, runtime->dma_area + pos + 1, count))
+		if (copy_to_iter(runtime->dma_area + pos + 1, count, dst) != count)
 			return -EFAULT;
 	} else {
-		if (copy_to_user(dst, runtime->dma_area + pos + 1, count - 1))
+		if (copy_to_iter(runtime->dma_area + pos + 1, count - 1, dst) != count - 1)
 			return -EFAULT;
-		if (put_user(runtime->dma_area[0],
-			     ((unsigned char __user *)dst) + count - 1))
+		if (copy_to_iter(runtime->dma_area, 1, dst) != 1)
 			return -EFAULT;
-	}
-	return 0;
-}
-
-static int snd_es1938_capture_copy_kernel(struct snd_pcm_substream *substream,
-					  int channel, unsigned long pos,
-					  void *dst, unsigned long count)
-{
-	struct snd_pcm_runtime *runtime = substream->runtime;
-	struct es1938 *chip = snd_pcm_substream_chip(substream);
-
-	if (snd_BUG_ON(pos + count > chip->dma1_size))
-		return -EINVAL;
-	if (pos + count < chip->dma1_size) {
-		memcpy(dst, runtime->dma_area + pos + 1, count);
-	} else {
-		memcpy(dst, runtime->dma_area + pos + 1, count - 1);
-		runtime->dma_area[0] = *((unsigned char *)dst + count - 1);
 	}
 	return 0;
 }
···
 	.prepare =	snd_es1938_capture_prepare,
 	.trigger =	snd_es1938_capture_trigger,
 	.pointer =	snd_es1938_capture_pointer,
-	.copy_user =	snd_es1938_capture_copy,
-	.copy_kernel =	snd_es1938_capture_copy_kernel,
+	.copy =		snd_es1938_capture_copy,
 };
 
 static int snd_es1938_new_pcm(struct es1938 *chip, int device)