diff --git a/bitbang_spi.c b/bitbang_spi.c
index 6316a55..b543fd4 100644
--- a/bitbang_spi.c
+++ b/bitbang_spi.c
@@ -26,46 +26,55 @@
 #include "chipdrivers.h"
 #include "spi.h"
 
-/* Length of half a clock period in usecs */
-int bitbang_spi_half_period = 0;
+/* Length of half a clock period in usecs. */
+static int bitbang_spi_half_period;
 
-enum bitbang_spi_master bitbang_spi_master = BITBANG_SPI_INVALID;
+static enum bitbang_spi_master bitbang_spi_master = BITBANG_SPI_INVALID;
 
-const struct bitbang_spi_master_entry bitbang_spi_master_table[] = {
+static const struct bitbang_spi_master_entry bitbang_spi_master_table[] = {
 	{}, /* This entry corresponds to BITBANG_SPI_INVALID. */
 };
 
 const int bitbang_spi_master_count = ARRAY_SIZE(bitbang_spi_master_table);
 
-void bitbang_spi_set_cs(int val)
+/* Note that CS# is active low, so val=0 means the chip is active. */
+static void bitbang_spi_set_cs(int val)
 {
 	bitbang_spi_master_table[bitbang_spi_master].set_cs(val);
 }
 
-void bitbang_spi_set_sck(int val)
+static void bitbang_spi_set_sck(int val)
 {
 	bitbang_spi_master_table[bitbang_spi_master].set_sck(val);
 }
 
-void bitbang_spi_set_mosi(int val)
+static void bitbang_spi_set_mosi(int val)
 {
 	bitbang_spi_master_table[bitbang_spi_master].set_mosi(val);
 }
 
-int bitbang_spi_get_miso(void)
+static int bitbang_spi_get_miso(void)
 {
 	return bitbang_spi_master_table[bitbang_spi_master].get_miso();
 }
 
-int bitbang_spi_init(void)
+int bitbang_spi_init(enum bitbang_spi_master master, int halfperiod)
 {
+	bitbang_spi_master = master;
+	bitbang_spi_half_period = halfperiod;
+
+	if (bitbang_spi_master == BITBANG_SPI_INVALID) {
+		msg_perr("Invalid bitbang SPI master. \n"
+			 "Please report a bug at flashrom@flashrom.org\n");
+		return 1;
+	}
 	bitbang_spi_set_cs(1);
 	bitbang_spi_set_sck(0);
-	buses_supported = CHIP_BUSTYPE_SPI;
+	bitbang_spi_set_mosi(0);
 	return 0;
 }
 
-uint8_t bitbang_spi_readwrite_byte(uint8_t val)
+static uint8_t bitbang_spi_readwrite_byte(uint8_t val)
 {
 	uint8_t ret = 0;
 	int i;
diff --git a/flash.h b/flash.h
index 2065109..c858eba 100644
--- a/flash.h
+++ b/flash.h
@@ -133,8 +133,6 @@
 
 extern const int bitbang_spi_master_count;
 
-extern enum bitbang_spi_master bitbang_spi_master;
-
 struct bitbang_spi_master_entry {
 	void (*set_cs) (int val);
 	void (*set_sck) (int val);
@@ -533,9 +531,7 @@
 int ft2232_spi_write_256(struct flashchip *flash, uint8_t *buf, int start, int len);
 
 /* bitbang_spi.c */
-extern int bitbang_spi_half_period;
-extern const struct bitbang_spi_master_entry bitbang_spi_master_table[];
-int bitbang_spi_init(void);
+int bitbang_spi_init(enum bitbang_spi_master master, int halfperiod);
 int bitbang_spi_send_command(unsigned int writecnt, unsigned int readcnt, const unsigned char *writearr, unsigned char *readarr);
 int bitbang_spi_read(struct flashchip *flash, uint8_t *buf, int start, int len);
 int bitbang_spi_write_256(struct flashchip *flash, uint8_t *buf, int start, int len);
diff --git a/hwaccess.h b/hwaccess.h
index c38ee6f..a230fa1 100644
--- a/hwaccess.h
+++ b/hwaccess.h
@@ -176,6 +176,10 @@
 #define __DARWIN__
 #endif
 
+/* Clarification about OUTB/OUTW/OUTL argument order:
+ * OUT[BWL](val, port)
+ */
+
 #if defined(__FreeBSD__) || defined(__DragonFly__)
   #include <machine/cpufunc.h>
   #define off64_t off_t