crypto: rockchip - use read_poll_timeout

Use read_poll_timeout instead of open coding it.
In the same time, fix indentation of related comment.
Reviewed-by: John Keeping <john@metanate.com>
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/rockchip/rk3288_crypto_ahash.c

@@ -10,6 +10,7 @@
  */
 #include <linux/device.h>
 #include <asm/unaligned.h>
+#include <linux/iopoll.h>
 #include "rk3288_crypto.h"
 
 /*
@@ -295,18 +296,17 @@ static int rk_hash_run(struct crypto_engine *engine, void *breq)
 		sg = sg_next(sg);
 	}
 
-		/*
-		 * it will take some time to process date after last dma
-		 * transmission.
-		 *
-		 * waiting time is relative with the last date len,
-		 * so cannot set a fixed time here.
-		 * 10us makes system not call here frequently wasting
-		 * efficiency, and make it response quickly when dma
-		 * complete.
-		 */
-	while (!CRYPTO_READ(tctx->dev, RK_CRYPTO_HASH_STS))
-		udelay(10);
+	/*
+	 * it will take some time to process date after last dma
+	 * transmission.
+	 *
+	 * waiting time is relative with the last date len,
+	 * so cannot set a fixed time here.
+	 * 10us makes system not call here frequently wasting
+	 * efficiency, and make it response quickly when dma
+	 * complete.
+	 */
+	readl_poll_timeout(tctx->dev->reg + RK_CRYPTO_HASH_STS, v, v == 0, 10, 1000);
 
 	for (i = 0; i < crypto_ahash_digestsize(tfm) / 4; i++) {
 		v = readl(tctx->dev->reg + RK_CRYPTO_HASH_DOUT_0 + i * 4);