gscsio(4) -- National Semiconductor Geode SC1100 Super I/O driver.

For now it only supports I2C-compatible ACCESS.bus interface,
so we use it as an i2c master controller.

ACCESS.bus interface is enabled and used on the PC Engines WRAP.1C
board.

4 files changed, 547 insertions, 2 deletions

diff --git a/sys/arch/i386/conf/GENERIC b/sys/arch/i386/conf/GENERIC
index fefeaa95437..0a644f1d9c8 100644
--- a/sys/arch/i386/conf/GENERIC
+++ b/sys/arch/i386/conf/GENERIC
@@ -1,4 +1,4 @@
-#	$OpenBSD: GENERIC,v 1.361 2004/05/23 03:23:00 deraadt Exp $
+#	$OpenBSD: GENERIC,v 1.362 2004/05/23 17:41:08 grange Exp $
 #
 #	GENERIC -- everything that's currently supported
 #
@@ -70,6 +70,9 @@ lm0	at isa? port 0x290
 #lm1	at isa? port 0x280
 #lm2	at isa? port 0x310
 nsclpcsio*	at isa?			# NS PC87366 hardware monitor
+gscsio*	at isa?				# NS Geode SC1100 Super I/O
+iic0	at gscsio?			# ACCESS.bus 1
+iic1	at gscsio?			# ACCESS.bus 2
 
 it0	at isa? port 0x290		# IT8705F, IT8712F and SiS970 hardware
 					# monitors
diff --git a/sys/dev/isa/files.isa b/sys/dev/isa/files.isa
index 8c8e3ef8a1e..5858dca16c6 100644
--- a/sys/dev/isa/files.isa
+++ b/sys/dev/isa/files.isa
@@ -1,4 +1,4 @@
-#	$OpenBSD: files.isa,v 1.86 2004/01/05 17:27:30 markus Exp $
+#	$OpenBSD: files.isa,v 1.87 2004/05/23 17:41:09 grange Exp $
 #	$NetBSD: files.isa,v 1.21 1996/05/16 03:45:55 mycroft Exp $
 #
 # Config file and device description for machine-independent ISA code.
@@ -383,6 +383,11 @@ device	nsclpcsio
 attach	nsclpcsio at isa with nsclpcsio_isa
 file	dev/isa/nsclpcsio_isa.c		nsclpcsio_isa
 
+# National Semiconductor Geode SC1100 Super I/O
+device	gscsio: i2cbus
+attach	gscsio at isa
+file	dev/isa/gscsio.c		gscsio
+
 # IT8705F, IT8712F and SiS970 hardware monitors
 device	it
 attach	it at isa
diff --git a/sys/dev/isa/gscsio.c b/sys/dev/isa/gscsio.c
new file mode 100644
index 00000000000..1a448892af6
--- /dev/null
+++ b/sys/dev/isa/gscsio.c
@@ -0,0 +1,448 @@
+/*	$OpenBSD: gscsio.c,v 1.1 2004/05/23 17:41:09 grange Exp $	*/
+/*
+ * Copyright (c) 2004 Alexander Yurchenko <grange@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * National Semiconductor Geode SC1100 Super I/O.
+ * Only ACCESS.bus logical device is supported.
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/device.h>
+#include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/proc.h>
+
+#include <machine/bus.h>
+
+#include <dev/i2c/i2cvar.h>
+
+#include <dev/isa/isareg.h>
+#include <dev/isa/isavar.h>
+
+#include <dev/isa/gscsioreg.h>
+
+struct gscsio_softc {
+	struct device sc_dev;
+
+	bus_space_tag_t sc_iot;
+	bus_space_handle_t sc_ioh;
+
+	int sc_ld_en[GSCSIO_LDNUM];
+	bus_space_handle_t sc_ld_ioh0[GSCSIO_LDNUM];
+	bus_space_handle_t sc_ld_ioh1[GSCSIO_LDNUM];
+
+	/* ACCESS.bus */
+	struct gscsio_acb {
+		void *sc;
+		bus_space_handle_t ioh;
+		struct lock buslock;
+	} sc_acb[2];
+	struct i2c_controller sc_acb1_tag;
+	struct i2c_controller sc_acb2_tag;
+};
+
+/* Supported logical devices description */
+static const struct {
+	const char *ld_name;
+	int ld_num;
+	int ld_iosize0;
+	int ld_iosize1;
+} gscsio_ld[] = {
+	{ "ACB1", GSCSIO_LDN_ACB1, 6, 0 },
+	{ "ACB2", GSCSIO_LDN_ACB2, 6, 0 },
+};
+
+int	gscsio_probe(struct device *, void *, void *);
+void	gscsio_attach(struct device *, struct device *, void *);
+
+void	gscsio_acb_init(struct gscsio_acb *, i2c_tag_t);
+int	gscsio_acb_wait(struct gscsio_acb *, int, int);
+void	gscsio_acb_reset(struct gscsio_acb *acb);
+
+int	gscsio_acb_acquire_bus(void *, int);
+void	gscsio_acb_release_bus(void *, int);
+int	gscsio_acb_send_start(void *, int);
+int	gscsio_acb_send_stop(void *, int);
+int	gscsio_acb_initiate_xfer(void *, uint16_t, int);
+int	gscsio_acb_read_byte(void *, uint8_t *, int);
+int	gscsio_acb_write_byte(void *, uint8_t, int);
+
+struct cfattach gscsio_ca = {
+	sizeof(struct gscsio_softc),
+	gscsio_probe,
+	gscsio_attach
+};
+
+struct cfdriver gscsio_cd = {
+	NULL, "gscsio", DV_DULL
+};
+
+#define ACB_READ(reg) \
+	bus_space_read_1(sc->sc_iot, acb->ioh, (reg))
+#define ACB_WRITE(reg, val) \
+	bus_space_write_1(sc->sc_iot, acb->ioh, (reg), (val))
+
+static __inline u_int8_t
+idxread(bus_space_tag_t iot, bus_space_handle_t ioh, int idx)
+{
+	bus_space_write_1(iot, ioh, GSCSIO_IDX, idx);
+
+	return (bus_space_read_1(iot, ioh, GSCSIO_DAT));
+}
+
+static __inline void
+idxwrite(bus_space_tag_t iot, bus_space_handle_t ioh, int idx, u_int8_t data)
+{
+	bus_space_write_1(iot, ioh, GSCSIO_IDX, idx);
+	bus_space_write_1(iot, ioh, GSCSIO_DAT, data);
+}
+
+static int
+ioprobe(bus_space_tag_t iot, int base)
+{
+	bus_space_handle_t ioh;
+	int rv = 0;
+
+	if (bus_space_map(iot, base, GSCSIO_IOSIZE, 0, &ioh))
+		return (0);
+	if (idxread(iot, ioh, GSCSIO_ID) == GSCSIO_ID_SC1100)
+		rv = 1;
+	bus_space_unmap(iot, ioh, GSCSIO_IOSIZE);
+
+	return (rv);
+}
+
+int
+gscsio_probe(struct device *parent, void *match, void *aux)
+{
+	struct isa_attach_args *ia = aux;
+	int iobase;
+
+	iobase = GSCSIO_IOBASE1;
+	if (ioprobe(ia->ia_iot, iobase))
+		goto found;
+	iobase = GSCSIO_IOBASE2;
+	if (ioprobe(ia->ia_iot, iobase))
+		goto found;
+
+	return (0);
+
+found:
+	ia->ipa_nio = 1;
+	ia->ipa_io[0].base = iobase;
+	ia->ipa_io[0].length = GSCSIO_IOSIZE;
+	ia->ipa_nmem = 0;
+	ia->ipa_nirq = 0;
+	ia->ipa_ndrq = 0;
+
+	return (1);
+}
+
+void
+gscsio_attach(struct device *parent, struct device *self, void *aux)
+{
+	struct gscsio_softc *sc = (void *)self;
+	struct isa_attach_args *ia = aux;
+	int i;
+	int iobase;
+
+	sc->sc_iot = ia->ia_iot;
+	if (bus_space_map(sc->sc_iot, ia->ipa_io[0].base, GSCSIO_IOSIZE,
+	    0, &sc->sc_ioh)) {
+		printf(": can't map I/O space\n");
+		return;
+	}
+	printf(": SC1100 SIO rev %d:",
+	    idxread(sc->sc_iot, sc->sc_ioh, GSCSIO_REV));
+
+	/* Configure all supported logical devices */
+	for (i = 0; i < sizeof (gscsio_ld) / sizeof(gscsio_ld[0]); i++) {
+		sc->sc_ld_en[gscsio_ld[i].ld_num] = 0;
+
+		/* Select the device and check if it's activated */
+		idxwrite(sc->sc_iot, sc->sc_ioh, GSCSIO_LDN,
+		    gscsio_ld[i].ld_num);
+		if ((idxread(sc->sc_iot, sc->sc_ioh, GSCSIO_ACT) &
+		    GSCSIO_ACT_EN) == 0)
+			continue;
+
+		/* Map I/O space 0 if necessary */
+		if (gscsio_ld[i].ld_iosize0 != 0) {
+			iobase = idxread(sc->sc_iot, sc->sc_ioh,
+			    GSCSIO_IO0_MSB);
+			iobase <<= 8;
+			iobase |= idxread(sc->sc_iot, sc->sc_ioh,
+			    GSCSIO_IO0_LSB);
+			if (bus_space_map(sc->sc_iot, iobase,
+			    gscsio_ld[i].ld_iosize0, 0,
+			    &sc->sc_ld_ioh0[gscsio_ld[i].ld_num]))
+				continue;
+		}
+
+		/* Map I/O space 1 if necessary */
+		if (gscsio_ld[i].ld_iosize1 != 0) {
+			iobase = idxread(sc->sc_iot, sc->sc_ioh,
+			    GSCSIO_IO1_MSB);
+			iobase <<= 8;
+			iobase |= idxread(sc->sc_iot, sc->sc_ioh,
+			    GSCSIO_IO1_LSB);
+			if (bus_space_map(sc->sc_iot, iobase,
+			    gscsio_ld[i].ld_iosize1, 0,
+			    &sc->sc_ld_ioh0[gscsio_ld[i].ld_num])) {
+				bus_space_unmap(sc->sc_iot,
+				    sc->sc_ld_ioh0[gscsio_ld[i].ld_num],
+				    gscsio_ld[i].ld_iosize0);
+				continue;
+			}
+		}
+
+		sc->sc_ld_en[gscsio_ld[i].ld_num] = 1;
+		printf(" %s", gscsio_ld[i].ld_name);
+	}
+	printf("\n");
+
+	/* Initialize ACCESS.bus 1 */
+	if (sc->sc_ld_en[GSCSIO_LDN_ACB1]) {
+		sc->sc_acb[0].sc = sc;
+		sc->sc_acb[0].ioh = sc->sc_ld_ioh0[GSCSIO_LDN_ACB1];
+		gscsio_acb_init(&sc->sc_acb[0], &sc->sc_acb1_tag);
+	}
+
+	/* Initialize ACCESS.bus 2 */
+	if (sc->sc_ld_en[GSCSIO_LDN_ACB2]) {
+		sc->sc_acb[1].sc = sc;
+		sc->sc_acb[1].ioh = sc->sc_ld_ioh0[GSCSIO_LDN_ACB2];
+		gscsio_acb_init(&sc->sc_acb[1], &sc->sc_acb2_tag);
+	}
+}
+
+void
+gscsio_acb_init(struct gscsio_acb *acb, i2c_tag_t tag)
+{
+	struct gscsio_softc *sc = acb->sc;
+	struct i2cbus_attach_args iba;
+
+	/* Enable ACB and configure clock frequency */
+	ACB_WRITE(GSCSIO_ACB_CTL2, GSCSIO_ACB_CTL2_EN |
+	    (GSCSIO_ACB_FREQ << GSCSIO_ACB_CTL2_FREQ_SHIFT));
+
+	/* Select polling mode */
+	ACB_WRITE(GSCSIO_ACB_CTL1, ACB_READ(GSCSIO_ACB_CTL1) &
+	    ~GSCSIO_ACB_CTL1_INTEN);
+
+	/* Disable slave address */
+	ACB_WRITE(GSCSIO_ACB_ADDR, ACB_READ(GSCSIO_ACB_ADDR) &
+	    ~GSCSIO_ACB_ADDR_SAEN);
+
+	/* Attach I2C framework */
+	tag->ic_cookie = acb;
+	tag->ic_acquire_bus = gscsio_acb_acquire_bus;
+	tag->ic_release_bus = gscsio_acb_release_bus;
+	tag->ic_send_start = gscsio_acb_send_start;
+	tag->ic_send_stop = gscsio_acb_send_stop;
+	tag->ic_initiate_xfer = gscsio_acb_initiate_xfer;
+	tag->ic_read_byte = gscsio_acb_read_byte;
+	tag->ic_write_byte = gscsio_acb_write_byte;
+
+	iba.iba_name = "iic";
+	iba.iba_tag = tag;
+	config_found(&sc->sc_dev, &iba, iicbus_print);
+}
+
+int
+gscsio_acb_wait(struct gscsio_acb *acb, int bits, int flags)
+{
+	struct gscsio_softc *sc = acb->sc;
+	u_int8_t st;
+	int i;
+
+	for (i = 0; i < 100; i++) {
+		st = ACB_READ(GSCSIO_ACB_ST);
+		if (st & GSCSIO_ACB_ST_BER) {
+			printf("%s: bus error, flags=0x%x\n",
+			    sc->sc_dev.dv_xname, flags);
+			gscsio_acb_reset(acb);
+			return (EIO);
+		}
+		if (st & GSCSIO_ACB_ST_NEGACK) {
+			printf("%s: negative ack, flags=0x%x\n",
+			    sc->sc_dev.dv_xname, flags);
+			gscsio_acb_reset(acb);
+			return (EIO);
+		}
+		if ((st & bits) == bits)
+			break;
+		delay(10);
+	}
+	if ((st & bits) != bits) {
+		printf("%s: timeout, flags=0x%x\n",
+		    sc->sc_dev.dv_xname, flags);
+		gscsio_acb_reset(acb);
+		return (ETIMEDOUT);
+	}
+
+	return (0);
+}
+
+void
+gscsio_acb_reset(struct gscsio_acb *acb)
+{
+	struct gscsio_softc *sc = acb->sc;
+	u_int8_t st, ctl;
+
+	/* Clear MASTER, NEGACK and BER */
+	st = ACB_READ(GSCSIO_ACB_ST);
+	st |= GSCSIO_ACB_ST_MASTER | GSCSIO_ACB_ST_NEGACK | GSCSIO_ACB_ST_BER;
+	ACB_WRITE(GSCSIO_ACB_ST, st);
+
+	/* Disable and re-enable ACB */
+	ACB_WRITE(GSCSIO_ACB_CTL2, 0);
+	ACB_WRITE(GSCSIO_ACB_CTL2, GSCSIO_ACB_CTL2_EN |
+	    (GSCSIO_ACB_FREQ << GSCSIO_ACB_CTL2_FREQ_SHIFT));
+
+	/* Send stop */
+	ctl = ACB_READ(GSCSIO_ACB_CTL1);
+	ctl |= GSCSIO_ACB_CTL1_STOP;
+	ACB_WRITE(GSCSIO_ACB_CTL1, ctl);
+}
+
+int
+gscsio_acb_acquire_bus(void *cookie, int flags)
+{
+	struct gscsio_acb *acb = cookie;
+
+	if (flags & I2C_F_POLL)
+		return (0);
+
+	return (lockmgr(&acb->buslock, LK_EXCLUSIVE, NULL, curproc));
+}
+
+void
+gscsio_acb_release_bus(void *cookie, int flags)
+{
+	struct gscsio_acb *acb = cookie;
+
+	if (flags & I2C_F_POLL)
+		return;
+
+	lockmgr(&acb->buslock, LK_RELEASE, NULL, curproc);
+}
+
+int
+gscsio_acb_send_start(void *cookie, int flags)
+{
+	struct gscsio_acb *acb = cookie;
+	struct gscsio_softc *sc = acb->sc;
+	u_int8_t ctl;
+
+	ctl = ACB_READ(GSCSIO_ACB_CTL1);
+	ctl |= GSCSIO_ACB_CTL1_START;
+	ACB_WRITE(GSCSIO_ACB_CTL1, ctl);
+
+	return (0);
+}
+
+int
+gscsio_acb_send_stop(void *cookie, int flags)
+{
+	struct gscsio_acb *acb = cookie;
+	struct gscsio_softc *sc = acb->sc;
+	u_int8_t ctl;
+
+	ctl = ACB_READ(GSCSIO_ACB_CTL1);
+	ctl |= GSCSIO_ACB_CTL1_STOP;
+	ACB_WRITE(GSCSIO_ACB_CTL1, ctl);
+
+	return (0);
+}
+
+int
+gscsio_acb_initiate_xfer(void *cookie, uint16_t addr, int flags)
+{
+	struct gscsio_acb *acb = cookie;
+	struct gscsio_softc *sc = acb->sc;
+	u_int8_t ctl;
+	int dir;
+	int error;
+
+	/* Issue start condition */
+	ctl = ACB_READ(GSCSIO_ACB_CTL1);
+	ctl |= GSCSIO_ACB_CTL1_START;
+	ACB_WRITE(GSCSIO_ACB_CTL1, ctl);
+
+	/* Wait for bus mastership */
+	if ((error = gscsio_acb_wait(acb,
+	    GSCSIO_ACB_ST_MASTER | GSCSIO_ACB_ST_SDAST, flags)))
+		return (error);
+
+	/* Send address byte */
+	dir = (flags & I2C_F_READ ? 1 : 0);
+	ACB_WRITE(GSCSIO_ACB_SDA, (addr << 1) | dir);
+
+	return (0);
+}
+
+int
+gscsio_acb_read_byte(void *cookie, uint8_t *bytep, int flags)
+{
+	struct gscsio_acb *acb = cookie;
+	struct gscsio_softc *sc = acb->sc;
+	u_int8_t ctl;
+	int error;
+
+	/* Wait for the bus to be ready */
+	if ((error = gscsio_acb_wait(acb, GSCSIO_ACB_ST_SDAST, flags)))
+		return (error);
+
+	/* Acknowledge the last byte */
+	if (flags & I2C_F_LAST) {
+		ctl = ACB_READ(GSCSIO_ACB_CTL1);
+		ctl |= GSCSIO_ACB_CTL1_ACK;
+		ACB_WRITE(GSCSIO_ACB_CTL1, ctl);
+	}
+
+	/* Read data byte */
+	*bytep = ACB_READ(GSCSIO_ACB_SDA);
+
+	return (0);
+}
+
+int
+gscsio_acb_write_byte(void *cookie, uint8_t byte, int flags)
+{
+	struct gscsio_acb *acb = cookie;
+	struct gscsio_softc *sc = acb->sc;
+	u_int8_t ctl;
+	int error;
+
+	/* Wait for the bus to be ready */
+	if ((error = gscsio_acb_wait(acb, GSCSIO_ACB_ST_SDAST, flags)))
+		return (error);
+
+	/* Send stop after the last byte */
+	if (flags & I2C_F_STOP) {
+		ctl = ACB_READ(GSCSIO_ACB_CTL1);
+		ctl |= GSCSIO_ACB_CTL1_STOP;
+		ACB_WRITE(GSCSIO_ACB_CTL1, ctl);
+	}
+
+	/* Write data byte */
+	ACB_WRITE(GSCSIO_ACB_SDA, byte);
+
+	return (0);
+}
diff --git a/sys/dev/isa/gscsioreg.h b/sys/dev/isa/gscsioreg.h
new file mode 100644
index 00000000000..dc8793b0bc4
--- /dev/null
+++ b/sys/dev/isa/gscsioreg.h
@@ -0,0 +1,89 @@
+/*	$OpenBSD: gscsioreg.h,v 1.1 2004/05/23 17:41:09 grange Exp $	*/
+/*
+ * Copyright (c) 2004 Alexander Yurchenko <grange@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * National Semiconductor Geode SC1100 Super I/O register definitions.
+ */
+
+/* Possible index-data register pair base addresses */
+#define GSCSIO_IOBASE1	0x2e
+#define GSCSIO_IOBASE2	0x15c
+#define GSCSIO_IOSIZE	2	/* I/O space size */
+
+/* Index-data register pair */
+#define GSCSIO_IDX	0x0	/* index register */
+#define GSCSIO_DAT	0x1	/* data register */
+
+/* SIO control and configuration registers */
+#define GSCSIO_LDN	0x07	/* logical device number */
+#define GSCSIO_LDN_ACB1		0x05	/* ACCESS.bus 1 */
+#define GSCSIO_LDN_ACB2		0x06	/* ACCESS.bus 2 */
+#define GSCSIO_ID	0x20	/* SIO ID */
+#define GSCSIO_ID_SC1100	0xf5	/* Geode SC1100 ID */
+#define GSCSIO_CFG1	0x21	/* configuration 1 */
+#define GSCSIO_CFG2	0x22	/* configuration 2 */
+#define GSCSIO_REV	0x27	/* revision ID */
+
+/* Logical device control and configuration registers */
+#define GSCSIO_ACT	0x30	/* logical device activation control */
+#define GSCSIO_ACT_EN		0x01	/* enabled */
+#define GSCSIO_IO0_MSB	0x60	/* I/O space 0 base bits [15:8] */
+#define GSCSIO_IO0_LSB	0x61	/* I/O space 0 base bits [7:0] */
+#define GSCSIO_IO1_MSB	0x62	/* I/O space 1 base bits [15:8] */
+#define GSCSIO_IO1_LSB	0x63	/* I/O space 1 base bits [7:0] */
+#define GSCSIO_INUM	0x70	/* interrupt number */
+#define GSCSIO_ITYPE	0x71	/* interrupt type */
+#define GSCSIO_DMA0	0x74	/* DMA channel 0 */
+#define GSCSIO_DMA1	0x75	/* DMA channel 1 */
+
+#define GSCSIO_LDNUM	6	/* total number of logical devices */
+
+/* ACB (ACCESS.bus) logical device registers */
+#define GSCSIO_ACB_SDA	0x00	/* serial data */
+#define GSCSIO_ACB_ST	0x01	/* status */
+#define GSCSIO_ACB_ST_XMIT	(1 << 0)	/* transmit mode active */
+#define GSCSIO_ACB_ST_MASTER	(1 << 1)	/* master mode active */
+#define GSCSIO_ACB_ST_NMATCH	(1 << 2)	/* new match */
+#define GSCSIO_ACB_ST_STASTR	(1 << 3)	/* stall after start */
+#define GSCSIO_ACB_ST_NEGACK	(1 << 4)	/* negative ack */
+#define GSCSIO_ACB_ST_BER	(1 << 5)	/* bus error */
+#define GSCSIO_ACB_ST_SDAST	(1 << 6)	/* wait or hold data */
+#define GSCSIO_ACB_ST_SLVSTP	(1 << 7)	/* slave stop */
+#define GSCSIO_ACB_CST	0x02	/* control status */
+#define GSCSIO_ACB_CST_BUSY	(1 << 0)	/* busy */
+#define GSCSIO_ACB_CST_BB	(1 << 1)	/* bus busy */
+#define GSCSIO_ACB_CST_MATCH	(1 << 2)	/* match address */
+#define GSCSIO_ACB_CST_GCMTCH	(1 << 3)	/* global call match */
+#define GSCSIO_ACB_CST_TSDA	(1 << 4)	/* test ABD line */
+#define GSCSIO_ACB_CST_TGABC	(1 << 5)	/* toggle ABC line */
+#define GSCSIO_ACB_CTL1	0x03	/* control 1 */
+#define GSCSIO_ACB_CTL1_START	(1 << 0)	/* start condition */
+#define GSCSIO_ACB_CTL1_STOP	(1 << 1)	/* stop condition */
+#define GSCSIO_ACB_CTL1_INTEN	(1 << 2)	/* interrupt enabled */
+#define GSCSIO_ACB_CTL1_ACK	(1 << 4)	/* acknowledge */
+#define GSCSIO_ACB_CTL1_GCMEN	(1 << 5)	/* global call match enable */
+#define GSCSIO_ACB_CTL1_NMINTE	(1 << 6)	/* new match intr enable */
+#define GSCSIO_ACB_CTL1_STASTRE	(1 << 7)	/* stall after start enable */
+#define GSCSIO_ACB_ADDR	0x04	/* own address */
+#define GSCSIO_ACB_ADDR_MASK	0x7f		/* address mask */
+#define GSCSIO_ACB_ADDR_SAEN	(1 << 7)	/* slave address enable */
+#define GSCSIO_ACB_CTL2	0x05	/* control 2 */
+#define GSCSIO_ACB_CTL2_EN	(1 << 0)	/* ACB enabled */
+#define GSCSIO_ACB_CTL2_FREQ_SHIFT	1	/* ACB frequency shift */
+#define GSCSIO_ACB_CTL2_FREQ_MASK	0x7f	/* ACB frequency mask */
+
+#define GSCSIO_ACB_FREQ		0x3c	/* standard I2C frequency 100kHz */