#define TWSIC0_EN 0x00000001 /* TWSI enable */
#define TWSIC0_MODE 0x00000002 /* 1 = 16-bit, 0 = 8-bit */
#define TWSIC0_SID 0x000003fc /* Slave ID */
-#define TWSIC0_SID_SHIFT 2
+/*
+ * Subtle trickery: the slave ID field starts with bit 2. But the
+ * Linux i2c stack wants to treat the bottommost bit as a separate
+ * read/write bit, which is why slave ID's are usually presented
+ * >>1. For consistency with that behavior, we shift over three
+ * bits instead of two.
+ */
+#define TWSIC0_SID_SHIFT 3
#define TWSIC0_CLKDIV 0x0007fc00 /* Clock divider */
#define TWSIC0_MASKACK 0x00400000 /* Mask ack from sensor */
#define TWSIC0_OVMAGIC 0x00800000 /* Make it work on OV sensors */