spi: spi-mtk-nor: support standard spi properties

Use default supports_op() to support spi-[rt]x-bus-width properties.
And check dummy op's byte length instead of its bus width for output.

Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
Link: https://lore.kernel.org/r/20200826091852.519138-1-ikjn@chromium.org
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-mtk-nor.c

@@ -211,25 +211,28 @@ static bool mtk_nor_supports_op(struct spi_mem *mem,
 	if (op->cmd.buswidth != 1)
 		return false;
 
-	/* DTR ops not supported. */
-	if (op->cmd.dtr || op->addr.dtr || op->dummy.dtr || op->data.dtr)
-		return false;
-	if (op->cmd.nbytes != 1)
-		return false;
-
 	if ((op->addr.nbytes == 3) || (op->addr.nbytes == 4)) {
-		if ((op->data.dir == SPI_MEM_DATA_IN) && mtk_nor_match_read(op))
-			return true;
-		else if (op->data.dir == SPI_MEM_DATA_OUT)
-			return (op->addr.buswidth == 1) &&
-			       (op->dummy.buswidth == 0) &&
-			       (op->data.buswidth == 1);
+		switch(op->data.dir) {
+		case SPI_MEM_DATA_IN:
+			if (!mtk_nor_match_read(op))
+				return false;
+			break;
+		case SPI_MEM_DATA_OUT:
+			if ((op->addr.buswidth != 1) ||
+			    (op->dummy.nbytes != 0) ||
+			    (op->data.buswidth != 1))
+				return false;
+			break;
+		default:
+			break;
+		}
 	}
 	len = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes;
 	if ((len > MTK_NOR_PRG_MAX_SIZE) ||
 	    ((op->data.nbytes) && (len == MTK_NOR_PRG_MAX_SIZE)))
 		return false;
-	return true;
+
+	return spi_mem_default_supports_op(mem, op);
 }
 
 static void mtk_nor_setup_bus(struct mtk_nor *sp, const struct spi_mem_op *op)