diff --git a/drivers/spi/spi-rspi.c b/drivers/spi/spi-rspi.c
index e6aa424..73f1a29 100644
--- a/drivers/spi/spi-rspi.c
+++ b/drivers/spi/spi-rspi.c
@@ -330,9 +330,7 @@
 			 struct spi_transfer *t)
 {
 	int remain = t->len;
-	u8 *data;
-
-	data = (u8 *)t->tx_buf;
+	const u8 *data = t->tx_buf;
 	while (remain > 0) {
 		rspi_write8(rspi, rspi_read8(rspi, RSPI_SPCR) | SPCR_TXMD,
 			    RSPI_SPCR);
@@ -358,12 +356,11 @@
 			 struct spi_transfer *t)
 {
 	int remain = t->len;
-	u8 *data;
+	const u8 *data = t->tx_buf;
 
 	rspi_write8(rspi, SPBFCR_TXRST, QSPI_SPBFCR);
 	rspi_write8(rspi, 0x00, QSPI_SPBFCR);
 
-	data = (u8 *)t->tx_buf;
 	while (remain > 0) {
 
 		if (rspi_wait_for_interrupt(rspi, SPSR_SPTEF, SPCR_SPTIE) < 0) {
@@ -399,8 +396,8 @@
 	wake_up_interruptible(&rspi->wait);
 }
 
-static int rspi_dma_map_sg(struct scatterlist *sg, void *buf, unsigned len,
-			   struct dma_chan *chan,
+static int rspi_dma_map_sg(struct scatterlist *sg, const void *buf,
+			   unsigned len, struct dma_chan *chan,
 			   enum dma_transfer_direction dir)
 {
 	sg_init_table(sg, 1);
@@ -440,12 +437,13 @@
 static int rspi_send_dma(struct rspi_data *rspi, struct spi_transfer *t)
 {
 	struct scatterlist sg;
-	void *buf = NULL;
+	const void *buf = NULL;
 	struct dma_async_tx_descriptor *desc;
 	unsigned len;
 	int ret = 0;
 
 	if (rspi->dma_width_16bit) {
+		void *tmp;
 		/*
 		 * If DMAC bus width is 16-bit, the driver allocates a dummy
 		 * buffer. And, the driver converts original data into the
@@ -454,13 +452,14 @@
 		 *  DMAC data:     1st byte, dummy, 2nd byte, dummy ...
 		 */
 		len = t->len * 2;
-		buf = kmalloc(len, GFP_KERNEL);
-		if (!buf)
+		tmp = kmalloc(len, GFP_KERNEL);
+		if (!tmp)
 			return -ENOMEM;
-		rspi_memory_to_8bit(buf, t->tx_buf, t->len);
+		rspi_memory_to_8bit(tmp, t->tx_buf, t->len);
+		buf = tmp;
 	} else {
 		len = t->len;
-		buf = (void *)t->tx_buf;
+		buf = t->tx_buf;
 	}
 
 	if (!rspi_dma_map_sg(&sg, buf, len, rspi->chan_tx, DMA_TO_DEVICE)) {
@@ -528,7 +527,7 @@
 
 	rspi_receive_init(rspi);
 
-	data = (u8 *)t->rx_buf;
+	data = t->rx_buf;
 	while (remain > 0) {
 		rspi_write8(rspi, rspi_read8(rspi, RSPI_SPCR) & ~SPCR_TXMD,
 			    RSPI_SPCR);
@@ -575,7 +574,7 @@
 
 	qspi_receive_init(rspi);
 
-	data = (u8 *)t->rx_buf;
+	data = t->rx_buf;
 	while (remain > 0) {
 
 		if (rspi_wait_for_interrupt(rspi, SPSR_SPTEF, SPCR_SPTIE) < 0) {
@@ -802,7 +801,7 @@
 
 static irqreturn_t rspi_irq(int irq, void *_sr)
 {
-	struct rspi_data *rspi = (struct rspi_data *)_sr;
+	struct rspi_data *rspi = _sr;
 	unsigned long spsr;
 	irqreturn_t ret = IRQ_NONE;
 	unsigned char disable_irq = 0;