mfd: mc13xxx-spi: make SPI buffers DMA-safe

index cbc1e5ed599c..f6bfbee9d9ef 100644
@@ -63,14 +63,13 @@ static const struct regmap_config mc13xxx_regmap_spi_config = {
 static int mc13xxx_spi_read(void *context, const void *reg, size_t reg_size,
 				void *val, size_t val_size)
 {
-	unsigned char w[4] = { *((unsigned char *) reg), 0, 0, 0};
-	unsigned char r[4];
 	unsigned char *p = val;
 	struct device *dev = context;
 	struct spi_device *spi = to_spi_device(dev);
+	struct mc13xxx *mc13xxx = dev_get_drvdata(dev);
 	struct spi_transfer t = {
-		.tx_buf = w,
-		.rx_buf = r,
+		.tx_buf = mc13xxx->wbuf,
+		.rx_buf = mc13xxx->rbuf,
 		.len = 4,
 	};
 

@@ -80,11 +79,12 @@ static int mc13xxx_spi_read(void *context, const void *reg, size_t reg_size,
 	if (val_size != 3 || reg_size != 1)
 		return -ENOTSUPP;
 
+	mc13xxx->wbuf[0] = *(unsigned char *)reg;
 	spi_message_init(&m);
 	spi_message_add_tail(&t, &m);
 	ret = spi_sync(spi, &m);
 
-	memcpy(p, &r[1], 3);
+	memcpy(p, &mc13xxx->rbuf[1], 3);
 
 	return ret;
 }

@@ -100,9 +100,9 @@ static int mc13xxx_spi_write(void *context, const void *data, size_t count)
 
 	/* include errata fix for spi audio problems */
 	if (*reg == MC13783_AUDIO_CODEC || *reg == MC13783_AUDIO_DAC)
-		spi_write(spi, data, count);
+		spi_write_then_read(spi, data, count, NULL, 0);
 
-	return spi_write(spi, data, count);
+	return spi_write_then_read(spi, data, count, NULL, 0);
 }
 
 /*

index 33677d1dcf66..1b35632e1d7e 100644
@@ -44,6 +44,10 @@ struct mc13xxx {
 	int flags;
 
 	int adcflags;
+#ifdef CONFIG_MFD_MC13XXX_SPI
+	unsigned char wbuf[4] ____cacheline_aligned;
+	unsigned char rbuf[4];
+#endif
 };
 
 int mc13xxx_common_init(struct device *dev);