diff --git a/src/cpu/samsung/exynos5420/spi.c b/src/cpu/samsung/exynos5420/spi.c
index 5c546cc14c..46b9ced4b3 100644
--- a/src/cpu/samsung/exynos5420/spi.c
+++ b/src/cpu/samsung/exynos5420/spi.c
@@ -258,15 +258,13 @@ int spi_claim_bus(struct spi_slave *slave)
 	return 0;
 }
 
-int spi_xfer(struct spi_slave *slave, const void *dout, unsigned int bitsout,
-	     void *din, unsigned int bitsin)
+int spi_xfer(struct spi_slave *slave, const void *dout, unsigned int out_bytes,
+	     void *din, unsigned int in_bytes)
 {
-	unsigned int out_bytes = bitsout / 8, in_bytes = bitsin / 8;
 	uint8_t *out_ptr = (uint8_t *)dout, *in_ptr = (uint8_t *)din;
 	int offset, todo, len;
 	int ret = 0;
 
-	ASSERT(bitsout % 8 == 0 && bitsin % 8 == 0);
 	len = MAX(out_bytes, in_bytes);
 
 	/*
diff --git a/src/drivers/spi/spi_flash.c b/src/drivers/spi/spi_flash.c
index 9b676ae61f..f3a5906a00 100644
--- a/src/drivers/spi/spi_flash.c
+++ b/src/drivers/spi/spi_flash.c
@@ -28,7 +28,7 @@ static void spi_flash_addr(u32 addr, u8 *cmd)
 
 int spi_flash_cmd(struct spi_slave *spi, u8 cmd, void *response, size_t len)
 {
-	int ret = spi_xfer(spi, &cmd, 8, response, len * 8);
+	int ret = spi_xfer(spi, &cmd, sizeof(cmd), response, len);
 	if (ret)
 		printk(BIOS_WARNING, "SF: Failed to send command %02x: %d\n", cmd, ret);
 
@@ -38,7 +38,7 @@ int spi_flash_cmd(struct spi_slave *spi, u8 cmd, void *response, size_t len)
 int spi_flash_cmd_read(struct spi_slave *spi, const u8 *cmd,
 		size_t cmd_len, void *data, size_t data_len)
 {
-	int ret = spi_xfer(spi, cmd, cmd_len * 8, data, data_len * 8);
+	int ret = spi_xfer(spi, cmd, cmd_len, data, data_len);
 	if (ret) {
 		printk(BIOS_WARNING, "SF: Failed to send read command (%zu bytes): %d\n",
 				data_len, ret);
@@ -55,7 +55,7 @@ int spi_flash_cmd_write(struct spi_slave *spi, const u8 *cmd, size_t cmd_len,
 	memcpy(buff, cmd, cmd_len);
 	memcpy(buff + cmd_len, data, data_len);
 
-	ret = spi_xfer(spi, buff, (cmd_len + data_len) * 8, NULL, 0);
+	ret = spi_xfer(spi, buff, cmd_len + data_len, NULL, 0);
 	if (ret) {
 		printk(BIOS_WARNING, "SF: Failed to send write command (%zu bytes): %d\n",
 				data_len, ret);
diff --git a/src/ec/google/chromeec/ec_spi.c b/src/ec/google/chromeec/ec_spi.c
index 012a4cace5..d6b7b0c4ea 100644
--- a/src/ec/google/chromeec/ec_spi.c
+++ b/src/ec/google/chromeec/ec_spi.c
@@ -31,8 +31,8 @@ static int crosec_spi_io(uint8_t *write_bytes, size_t write_size,
 	int rv;
 
 	spi_claim_bus(slave);
-	rv = spi_xfer(slave, write_bytes, write_size * 8, read_bytes,
-		      read_size * 8);
+	rv = spi_xfer(slave, write_bytes, write_size, read_bytes,
+		      read_size);
 	spi_release_bus(slave);
 
 	if (rv != 0) {
diff --git a/src/include/spi-generic.h b/src/include/spi-generic.h
index b7a14f9342..6c62de6d1d 100644
--- a/src/include/spi-generic.h
+++ b/src/include/spi-generic.h
@@ -120,27 +120,17 @@ void spi_release_bus(struct spi_slave *slave);
 /*-----------------------------------------------------------------------
  * SPI transfer
  *
- * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
- * "bitlen" bits in the SPI MISO port.  That's just the way SPI works.
- *
- * The source of the outgoing bits is the "dout" parameter and the
- * destination of the input bits is the "din" parameter.  Note that "dout"
- * and "din" can point to the same memory location, in which case the
- * input data overwrites the output data (since both are buffered by
- * temporary variables, this is OK).
- *
  * spi_xfer() interface:
  *   slave:	The SPI slave which will be sending/receiving the data.
- *   dout:	Pointer to a string of bits to send out.  The bits are
- *		held in a byte array and are sent MSB first.
- *   bitsout:	How many bits to write.
- *   din:	Pointer to a string of bits that will be filled in.
- *   bitsin:	How many bits to read.
+ *   dout:	Pointer to a string of bytes to send out.
+ *   bytesout:	How many bytes to write.
+ *   din:	Pointer to a string of bytes that will be filled in.
+ *   bytesin:	How many bytes to read.
  *
  *   Returns: 0 on success, not 0 on failure
  */
-int  spi_xfer(struct spi_slave *slave, const void *dout, unsigned int bitsout,
-		void *din, unsigned int bitsin);
+int  spi_xfer(struct spi_slave *slave, const void *dout, unsigned int bytesout,
+		void *din, unsigned int bytesin);
 
 /*-----------------------------------------------------------------------
  * Determine if a SPI chipselect is valid.
@@ -196,7 +186,7 @@ static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte)
 	dout[0] = byte;
 	dout[1] = 0;
 
-	ret = spi_xfer(slave, dout, 16, din, 16);
+	ret = spi_xfer(slave, dout, 2, din, 2);
 	return ret < 0 ? ret : din[1];
 }
 
diff --git a/src/soc/intel/baytrail/spi.c b/src/soc/intel/baytrail/spi.c
index d75caca7af..b649f53411 100644
--- a/src/soc/intel/baytrail/spi.c
+++ b/src/soc/intel/baytrail/spi.c
@@ -500,7 +500,7 @@ static int ich_status_poll(u16 bitmask, int wait_til_set)
 }
 
 int spi_xfer(struct spi_slave *slave, const void *dout,
-		unsigned int bitsout, void *din, unsigned int bitsin)
+		unsigned int bytesout, void *din, unsigned int bytesin)
 {
 	uint16_t control;
 	int16_t opcode_index;
@@ -508,26 +508,21 @@ int spi_xfer(struct spi_slave *slave, const void *dout,
 	int status;
 
 	spi_transaction trans = {
-		dout, bitsout / 8,
-		din, bitsin / 8,
+		dout, bytesout,
+		din, bytesin,
 		0xff, 0xff, 0
 	};
 
 	/* There has to always at least be an opcode. */
-	if (!bitsout || !dout) {
+	if (!bytesout || !dout) {
 		printk(BIOS_DEBUG, "ICH SPI: No opcode for transfer\n");
 		return -1;
 	}
 	/* Make sure if we read something we have a place to put it. */
-	if (bitsin != 0 && !din) {
+	if (bytesin != 0 && !din) {
 		printk(BIOS_DEBUG, "ICH SPI: Read but no target buffer\n");
 		return -1;
 	}
-	/* Right now we don't support writing partial bytes. */
-	if (bitsout % 8 || bitsin % 8) {
-		printk(BIOS_DEBUG, "ICH SPI: Accessing partial bytes not supported\n");
-		return -1;
-	}
 
 	if (ich_status_poll(SPIS_SCIP, 0) == -1)
 		return -1;
diff --git a/src/soc/intel/fsp_baytrail/spi.c b/src/soc/intel/fsp_baytrail/spi.c
index 5e8da95d3e..50f11231da 100644
--- a/src/soc/intel/fsp_baytrail/spi.c
+++ b/src/soc/intel/fsp_baytrail/spi.c
@@ -498,7 +498,7 @@ static int ich_status_poll(u16 bitmask, int wait_til_set)
 }
 
 int spi_xfer(struct spi_slave *slave, const void *dout,
-		unsigned int bitsout, void *din, unsigned int bitsin)
+		unsigned int bytesout, void *din, unsigned int bytesin)
 {
 	uint16_t control;
 	int16_t opcode_index;
@@ -506,26 +506,21 @@ int spi_xfer(struct spi_slave *slave, const void *dout,
 	int status;
 
 	spi_transaction trans = {
-		dout, bitsout / 8,
-		din, bitsin / 8,
+		dout, bytesout,
+		din, bytesin,
 		0xff, 0xff, 0
 	};
 
 	/* There has to always at least be an opcode. */
-	if (!bitsout || !dout) {
+	if (!bytesout || !dout) {
 		printk(BIOS_DEBUG, "ICH SPI: No opcode for transfer\n");
 		return -1;
 	}
 	/* Make sure if we read something we have a place to put it. */
-	if (bitsin != 0 && !din) {
+	if (bytesin != 0 && !din) {
 		printk(BIOS_DEBUG, "ICH SPI: Read but no target buffer\n");
 		return -1;
 	}
-	/* Right now we don't support writing partial bytes. */
-	if (bitsout % 8 || bitsin % 8) {
-		printk(BIOS_DEBUG, "ICH SPI: Accessing partial bytes not supported\n");
-		return -1;
-	}
 
 	if (ich_status_poll(SPIS_SCIP, 0) == -1)
 		return -1;
diff --git a/src/southbridge/amd/agesa/hudson/spi.c b/src/southbridge/amd/agesa/hudson/spi.c
index c19d1a0ff8..720b26f83e 100644
--- a/src/southbridge/amd/agesa/hudson/spi.c
+++ b/src/southbridge/amd/agesa/hudson/spi.c
@@ -87,21 +87,14 @@ void spi_init(void)
 }
 
 int spi_xfer(struct spi_slave *slave, const void *dout,
-		unsigned int bitsout, void *din, unsigned int bitsin)
+		unsigned int bytesout, void *din, unsigned int bytesin)
 {
 	/* First byte is cmd which can not being sent through FIFO. */
-	uint8_t cmd = *(uint8_t *)dout++;
-	uint8_t readoffby1;
-#if !CONFIG_SOUTHBRIDGE_AMD_AGESA_YANGTZE
-	uint8_t readwrite;
-#endif
-	uint8_t bytesout, bytesin;
-	uint8_t count;
-
-	bitsout -= 8;
-	bytesout = bitsout / 8;
-	bytesin  = bitsin / 8;
+	u8 cmd = *(u8 *)dout++;
+	u8 readoffby1;
+	u8 count;
 
+	bytesout--;
 	readoffby1 = bytesout ? 0 : 1;
 
 #if CONFIG_SOUTHBRIDGE_AMD_AGESA_YANGTZE
@@ -110,7 +103,7 @@ int spi_xfer(struct spi_slave *slave, const void *dout,
 	spi_write(0x1E, 6);
 	spi_write(0x1F, bytesin);  /* SpiExtRegIndx [6] - RxByteCount */
 #else
-	readwrite = (bytesin + readoffby1) << 4 | bytesout;
+	u8 readwrite = (bytesin + readoffby1) << 4 | bytesout;
 	spi_write(SPI_REG_CNTRL01, readwrite);
 #endif
 	spi_write(SPI_REG_OPCODE, cmd);
diff --git a/src/southbridge/amd/cimx/sb800/spi.c b/src/southbridge/amd/cimx/sb800/spi.c
index d059f5eb00..a46349e933 100644
--- a/src/southbridge/amd/cimx/sb800/spi.c
+++ b/src/southbridge/amd/cimx/sb800/spi.c
@@ -57,18 +57,15 @@ void spi_init()
 }
 
 int spi_xfer(struct spi_slave *slave, const void *dout,
-		unsigned int bitsout, void *din, unsigned int bitsin)
+		unsigned int bytesout, void *din, unsigned int bytesin)
 {
 	/* First byte is cmd which can not being sent through FIFO. */
 	u8 cmd = *(u8 *)dout++;
 	u8 readoffby1;
 	u8 readwrite;
-	u8 bytesout, bytesin;
 	u8 count;
 
-	bitsout -= 8;
-	bytesout = bitsout / 8;
-	bytesin  = bitsin / 8;
+	bytesout--;
 
 	readoffby1 = bytesout ? 0 : 1;
 
diff --git a/src/southbridge/intel/common/spi.c b/src/southbridge/intel/common/spi.c
index 14d2f54d28..76fd22691f 100644
--- a/src/southbridge/intel/common/spi.c
+++ b/src/southbridge/intel/common/spi.c
@@ -551,7 +551,7 @@ static int spi_is_multichip (void)
 }
 
 int spi_xfer(struct spi_slave *slave, const void *dout,
-		unsigned int bitsout, void *din, unsigned int bitsin)
+		unsigned int bytesout, void *din, unsigned int bytesin)
 {
 	uint16_t control;
 	int16_t opcode_index;
@@ -559,26 +559,21 @@ int spi_xfer(struct spi_slave *slave, const void *dout,
 	int status;
 
 	spi_transaction trans = {
-		dout, bitsout / 8,
-		din, bitsin / 8,
+		dout, bytesout,
+		din, bytesin,
 		0xff, 0xff, 0
 	};
 
 	/* There has to always at least be an opcode. */
-	if (!bitsout || !dout) {
+	if (!bytesout || !dout) {
 		printk(BIOS_DEBUG, "ICH SPI: No opcode for transfer\n");
 		return -1;
 	}
 	/* Make sure if we read something we have a place to put it. */
-	if (bitsin != 0 && !din) {
+	if (bytesin != 0 && !din) {
 		printk(BIOS_DEBUG, "ICH SPI: Read but no target buffer\n");
 		return -1;
 	}
-	/* Right now we don't support writing partial bytes. */
-	if (bitsout % 8 || bitsin % 8) {
-		printk(BIOS_DEBUG, "ICH SPI: Accessing partial bytes not supported\n");
-		return -1;
-	}
 
 	if (ich_status_poll(SPIS_SCIP, 0) == -1)
 		return -1;