i2c: add i2c_core and prepare for new multibus support

This Patch introduce the new i2c_core file, which holds
the I2C core functions, for the rework of the multibus/
multiadapter support.
Also adds changes in i2c.h for the new I2C multibus/multiadapter
support. This new support can be activated with the
CONFIG_SYS_I2C define.

Signed-off-by: Heiko Schocher <hs@denx.de>
Signed-off-by: Simon Glass <sjg@chromium.org>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Stephen Warren <swarren@wwwdotorg.org>

drivers/i2c/Makefile

@@ -46,6 +46,7 @@ COBJS-$(CONFIG_TSI108_I2C) += tsi108_i2c.o
 COBJS-$(CONFIG_U8500_I2C) += u8500_i2c.o
 COBJS-$(CONFIG_SH_I2C) += sh_i2c.o
 COBJS-$(CONFIG_SH_SH7734_I2C) += sh_sh7734_i2c.o
+COBJS-$(CONFIG_SYS_I2C) += i2c_core.o
 COBJS-$(CONFIG_ZYNQ_I2C) += zynq_i2c.o
 
 COBJS	:= $(COBJS-y)

drivers/i2c/i2c_core.c

+/*
+ * Copyright (C) 2009 Sergey Kubushyn <ksi@koi8.net>
+ *
+ * (C) Copyright 2012
+ * Heiko Schocher, DENX Software Engineering, hs@denx.de.
+ *
+ * Multibus/multiadapter I2C core functions (wrappers)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include <common.h>
+#include <i2c.h>
+
+struct i2c_adapter *i2c_get_adapter(int index)
+{
+	struct i2c_adapter *i2c_adap_p = ll_entry_start(struct i2c_adapter,
+						i2c);
+	int max = ll_entry_count(struct i2c_adapter, i2c);
+	int i;
+
+	if (index >= max) {
+		printf("Error, wrong i2c adapter %d max %d possible\n",
+		       index, max);
+		return i2c_adap_p;
+	}
+	if (index == 0)
+		return i2c_adap_p;
+
+	for (i = 0; i < index; i++)
+		i2c_adap_p++;
+
+	return i2c_adap_p;
+}
+
+#if !defined(CONFIG_SYS_I2C_DIRECT_BUS)
+struct i2c_bus_hose i2c_bus[CONFIG_SYS_NUM_I2C_BUSES] =
+			CONFIG_SYS_I2C_BUSES;
+#endif
+
+DECLARE_GLOBAL_DATA_PTR;
+
+void i2c_reloc_fixup(void)
+{
+#if defined(CONFIG_NEEDS_MANUAL_RELOC)
+	struct i2c_adapter *i2c_adap_p = ll_entry_start(struct i2c_adapter,
+						i2c);
+	struct i2c_adapter *tmp = i2c_adap_p;
+	int max = ll_entry_count(struct i2c_adapter, i2c);
+	int		i;
+	unsigned long	addr;
+
+	if (gd->reloc_off == 0)
+		return;
+
+	for (i = 0; i < max; i++) {
+		/* adapter itself */
+		addr = (unsigned long)i2c_adap_p;
+		addr += gd->reloc_off;
+		i2c_adap_p = (struct i2c_adapter *)addr;
+		/* i2c_init() */
+		addr = (unsigned long)i2c_adap_p->init;
+		addr += gd->reloc_off;
+		i2c_adap_p->init = (void (*)(int, int))addr;
+		/* i2c_probe() */
+		addr = (unsigned long)i2c_adap_p->probe;
+		addr += gd->reloc_off;
+		i2c_adap_p->probe = (int (*)(uint8_t))addr;
+		/* i2c_read() */
+		addr = (unsigned long)i2c_adap_p->read;
+		addr += gd->reloc_off;
+		i2c_adap_p->read = (int (*)(uint8_t, uint, int, uint8_t *,
+					int))addr;
+		/* i2c_write() */
+		addr = (unsigned long)i2c_adap_p->write;
+		addr += gd->reloc_off;
+		i2c_adap_p->write = (int (*)(uint8_t, uint, int, uint8_t *,
+					int))addr;
+		/* i2c_set_bus_speed() */
+		addr = (unsigned long)i2c_adap_p->set_bus_speed;
+		addr += gd->reloc_off;
+		i2c_adap_p->set_bus_speed = (uint (*)(uint))addr;
+		/* name */
+		addr = (unsigned long)i2c_adap_p->name;
+		addr += gd->reloc_off;
+		i2c_adap_p->name = (char *)addr;
+		tmp++;
+		i2c_adap_p = tmp;
+	}
+#endif
+}
+
+#ifndef CONFIG_SYS_I2C_DIRECT_BUS
+/*
+ * i2c_mux_set()
+ * -------------
+ *
+ * This turns on the given channel on I2C multiplexer chip connected to
+ * a given I2C adapter directly or via other multiplexers. In the latter
+ * case the entire multiplexer chain must be initialized first starting
+ * with the one connected directly to the adapter. When disabling a chain
+ * muxes must be programmed in reverse order, starting with the one
+ * farthest from the adapter.
+ *
+ * mux_id is the multiplexer chip type from defined in i2c.h. So far only
+ * NXP (Philips) PCA954x multiplexers are supported. Switches are NOT
+ * supported (anybody uses them?)
+ */
+
+static int i2c_mux_set(struct i2c_adapter *adap, int mux_id, int chip,
+			int channel)
+{
+	uint8_t	buf;
+	int ret;
+
+	/* channel < 0 - turn off the mux */
+	if (channel < 0) {
+		buf = 0;
+		ret = adap->write(adap, chip, 0, 0, &buf, 1);
+		if (ret)
+			printf("%s: Could not turn off the mux.\n", __func__);
+		return ret;
+	}
+
+	switch (mux_id) {
+	case I2C_MUX_PCA9540_ID:
+	case I2C_MUX_PCA9542_ID:
+		if (channel > 1)
+			return -1;
+		buf = (uint8_t)((channel & 0x01) | (1 << 2));
+		break;
+	case I2C_MUX_PCA9544_ID:
+		if (channel > 3)
+			return -1;
+		buf = (uint8_t)((channel & 0x03) | (1 << 2));
+		break;
+	case I2C_MUX_PCA9547_ID:
+		if (channel > 7)
+			return -1;
+		buf = (uint8_t)((channel & 0x07) | (1 << 3));
+		break;
+	default:
+		printf("%s: wrong mux id: %d\n", __func__, mux_id);
+		return -1;
+	}
+
+	ret = adap->write(adap, chip, 0, 0, &buf, 1);
+	if (ret)
+		printf("%s: could not set mux: id: %d chip: %x channel: %d\n",
+		       __func__, mux_id, chip, channel);
+	return ret;
+}
+
+static int i2c_mux_set_all(void)
+{
+	struct i2c_bus_hose *i2c_bus_tmp = &i2c_bus[I2C_BUS];
+	int i;
+
+	/* Connect requested bus if behind muxes */
+	if (i2c_bus_tmp->next_hop[0].chip != 0) {
+		/* Set all muxes along the path to that bus */
+		for (i = 0; i < CONFIG_SYS_I2C_MAX_HOPS; i++) {
+			int	ret;
+
+			if (i2c_bus_tmp->next_hop[i].chip == 0)
+				break;
+
+			ret = i2c_mux_set(I2C_ADAP,
+					i2c_bus_tmp->next_hop[i].mux.id,
+					i2c_bus_tmp->next_hop[i].chip,
+					i2c_bus_tmp->next_hop[i].channel);
+			if (ret != 0)
+				return ret;
+		}
+	}
+	return 0;
+}
+
+static int i2c_mux_disconnet_all(void)
+{
+	struct	i2c_bus_hose *i2c_bus_tmp = &i2c_bus[I2C_BUS];
+	int	i;
+	uint8_t	buf;
+
+	if (I2C_ADAP->init_done == 0)
+		return 0;
+
+	/* Disconnect current bus (turn off muxes if any) */
+	if ((i2c_bus_tmp->next_hop[0].chip != 0) &&
+	    (I2C_ADAP->init_done != 0)) {
+		i = CONFIG_SYS_I2C_MAX_HOPS;
+		do {
+			uint8_t	chip;
+			int ret;
+
+			chip = i2c_bus_tmp->next_hop[--i].chip;
+			if (chip == 0)
+				continue;
+
+			ret = I2C_ADAP->write(I2C_ADAP, chip, 0, 0, &buf, 1);
+			if (ret != 0) {
+				printf("i2c: mux diconnect error\n");
+				return ret;
+			}
+		} while (i > 0);
+	}
+
+	return 0;
+}
+#endif
+
+/*
+ * i2c_init_bus():
+ * ---------------
+ *
+ * Initializes one bus. Will initialize the parent adapter. No current bus
+ * changes, no mux (if any) setup.
+ */
+static void i2c_init_bus(unsigned int bus_no, int speed, int slaveaddr)
+{
+	if (bus_no >= CONFIG_SYS_NUM_I2C_BUSES)
+		return;
+
+	I2C_ADAP->init(I2C_ADAP, speed, slaveaddr);
+
+	if (gd->flags & GD_FLG_RELOC) {
+		I2C_ADAP->init_done = 1;
+		I2C_ADAP->speed = speed;
+		I2C_ADAP->slaveaddr = slaveaddr;
+	}
+}
+
+/* implement possible board specific board init */
+static void __def_i2c_init_board(void)
+{
+}
+void i2c_init_board(void)
+	__attribute__((weak, alias("__def_i2c_init_board")));
+
+/*
+ * i2c_init_all():
+ *
+ * not longer needed, will deleted. Actual init the SPD_BUS
+ * for compatibility.
+ * i2c_adap[] must be initialized beforehead with function pointers and
+ * data, including speed and slaveaddr.
+ */
+void i2c_init_all(void)
+{
+	i2c_init_board();
+	i2c_set_bus_num(CONFIG_SYS_SPD_BUS_NUM);
+	return;
+}
+
+/*
+ * i2c_get_bus_num():
+ * ------------------
+ *
+ *  Returns index of currently active I2C bus.  Zero-based.
+ */
+unsigned int i2c_get_bus_num(void)
+{
+	return gd->cur_i2c_bus;
+}
+
+/*
+ * i2c_set_bus_num():
+ * ------------------
+ *
+ *  Change the active I2C bus. Subsequent read/write calls will
+ *  go to this one. Sets all of the muxes in a proper condition
+ *  if that bus is behind muxes.
+ *  If previously selected bus is behind the muxes turns off all the
+ *  muxes along the path to that bus.
+ *
+ *	bus - bus index, zero based
+ *
+ *	Returns: 0 on success, not 0 on failure
+ */
+int i2c_set_bus_num(unsigned int bus)
+{
+	int max = ll_entry_count(struct i2c_adapter, i2c);
+
+	if (I2C_ADAPTER(bus) >= max) {
+		printf("Error, wrong i2c adapter %d max %d possible\n",
+		       I2C_ADAPTER(bus), max);
+		return -2;
+	}
+#ifndef CONFIG_SYS_I2C_DIRECT_BUS
+	if (bus >= CONFIG_SYS_NUM_I2C_BUSES)
+		return -1;
+#endif
+
+	if ((bus == I2C_BUS) && (I2C_ADAP->init_done > 0))
+		return 0;
+
+#ifndef CONFIG_SYS_I2C_DIRECT_BUS
+	i2c_mux_disconnet_all();
+#endif
+
+	gd->cur_i2c_bus = bus;
+	if (I2C_ADAP->init_done == 0)
+		i2c_init_bus(bus, I2C_ADAP->speed, I2C_ADAP->slaveaddr);
+
+#ifndef CONFIG_SYS_I2C_DIRECT_BUS
+	i2c_mux_set_all();
+#endif
+	return 0;
+}
+
+/*
+ * Probe the given I2C chip address.  Returns 0 if a chip responded,
+ * not 0 on failure.
+ */
+int i2c_probe(uint8_t chip)
+{
+	return I2C_ADAP->probe(I2C_ADAP, chip);
+}
+
+/*
+ * Read/Write interface:
+ *   chip:    I2C chip address, range 0..127
+ *   addr:    Memory (register) address within the chip
+ *   alen:    Number of bytes to use for addr (typically 1, 2 for larger
+ *              memories, 0 for register type devices with only one
+ *              register)
+ *   buffer:  Where to read/write the data
+ *   len:     How many bytes to read/write
+ *
+ *   Returns: 0 on success, not 0 on failure
+ */
+int i2c_read(uint8_t chip, unsigned int addr, int alen,
+				uint8_t *buffer, int len)
+{
+	return I2C_ADAP->read(I2C_ADAP, chip, addr, alen, buffer, len);
+}
+
+int i2c_write(uint8_t chip, unsigned int addr, int alen,
+				uint8_t *buffer, int len)
+{
+	return I2C_ADAP->write(I2C_ADAP, chip, addr, alen, buffer, len);
+}
+
+unsigned int i2c_set_bus_speed(unsigned int speed)
+{
+	unsigned int ret;
+
+	if (I2C_ADAP->set_bus_speed == NULL)
+		return 0;
+	ret = I2C_ADAP->set_bus_speed(I2C_ADAP, speed);
+	if (gd->flags & GD_FLG_RELOC)
+		I2C_ADAP->speed = ret;
+
+	return ret;
+}
+
+unsigned int i2c_get_bus_speed(void)
+{
+	struct i2c_adapter *cur = I2C_ADAP;
+	return cur->speed;
+}
+
+uint8_t i2c_reg_read(uint8_t addr, uint8_t reg)
+{
+	uint8_t buf;
+
+#ifdef CONFIG_8xx
+	/* MPC8xx needs this.  Maybe one day we can get rid of it. */
+	/* maybe it is now the time for it ... */
+	i2c_set_bus_num(i2c_get_bus_num());
+#endif
+	i2c_read(addr, reg, 1, &buf, 1);
+
+#ifdef DEBUG
+	printf("%s: bus=%d addr=0x%02x, reg=0x%02x, val=0x%02x\n",
+	       __func__, i2c_get_bus_num(), addr, reg, buf);
+#endif
+
+	return buf;
+}
+
+void i2c_reg_write(uint8_t addr, uint8_t reg, uint8_t val)
+{
+#ifdef CONFIG_8xx
+	/* MPC8xx needs this.  Maybe one day we can get rid of it. */
+	/* maybe it is now the time for it ... */
+	i2c_set_bus_num(i2c_get_bus_num());
+#endif
+
+#ifdef DEBUG
+	printf("%s: bus=%d addr=0x%02x, reg=0x%02x, val=0x%02x\n",
+	       __func__, i2c_get_bus_num(), addr, reg, val);
+#endif
+
+	i2c_write(addr, reg, 1, &val, 1);
+}
+
+void __i2c_init(int speed, int slaveaddr)
+{
+	i2c_init_bus(i2c_get_bus_num(), speed, slaveaddr);
+}
+void i2c_init(int speed, int slaveaddr)
+	__attribute__((weak, alias("__i2c_init")));

include/asm-generic/global_data.h

@@ -84,6 +84,9 @@ typedef struct global_data {
 	char env_buf[32];	/* buffer for getenv() before reloc. */
 #ifdef CONFIG_TRACE
 	void		*trace_buff;	/* The trace buffer */
+#endif
+#if defined(CONFIG_SYS_I2C)
+	int		cur_i2c_bus;	/* current used i2c bus */
 #endif
 	struct arch_global_data arch;	/* architecture-specific data */
 } gd_t;

include/i2c.h

 /*
+ * Copyright (C) 2009 Sergey Kubushyn <ksi@koi8.net>
+ * Copyright (C) 2009 - 2013 Heiko Schocher <hs@denx.de>
+ * Changes for multibus/multiadapter I2C support.
+ *
  * (C) Copyright 2001
  * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
  *
@@ -46,16 +50,14 @@
  */
 #define I2C_RXTX_LEN	128	/* maximum tx/rx buffer length */
 
-#ifdef	CONFIG_I2C_MULTI_BUS
-#define	MAX_I2C_BUS			2
-#define	I2C_MULTI_BUS			1
+#if !defined(CONFIG_SYS_I2C_MAX_HOPS)
+/* no muxes used bus = i2c adapters */
+#define CONFIG_SYS_I2C_DIRECT_BUS	1
+#define CONFIG_SYS_I2C_MAX_HOPS		0
+#define CONFIG_SYS_NUM_I2C_BUSES	ll_entry_count(struct i2c_adapter, i2c)
 #else
-#define	MAX_I2C_BUS			1
-#define	I2C_MULTI_BUS			0
-#endif
-
-#if !defined(CONFIG_SYS_MAX_I2C_BUS)
-#define CONFIG_SYS_MAX_I2C_BUS		MAX_I2C_BUS
+/* we use i2c muxes */
+#undef CONFIG_SYS_I2C_DIRECT_BUS
 #endif
 
 /* define the I2C bus number for RTC and DTT if not already done */
@@ -69,6 +71,88 @@
 #define CONFIG_SYS_SPD_BUS_NUM		0
 #endif
 
+struct i2c_adapter {
+	void		(*init)(struct i2c_adapter *adap, int speed,
+				int slaveaddr);
+	int		(*probe)(struct i2c_adapter *adap, uint8_t chip);
+	int		(*read)(struct i2c_adapter *adap, uint8_t chip,
+				uint addr, int alen, uint8_t *buffer,
+				int len);
+	int		(*write)(struct i2c_adapter *adap, uint8_t chip,
+				uint addr, int alen, uint8_t *buffer,
+				int len);
+	uint		(*set_bus_speed)(struct i2c_adapter *adap,
+				uint speed);
+	int		speed;
+	int		slaveaddr;
+	int		init_done;
+	int		hwadapnr;
+	char		*name;
+};
+
+#define U_BOOT_I2C_MKENT_COMPLETE(_init, _probe, _read, _write, \
+		_set_speed, _speed, _slaveaddr, _hwadapnr, _name) \
+	{ \
+		.init		=	_init, \
+		.probe		=	_probe, \
+		.read		=	_read, \
+		.write		=	_write, \
+		.set_bus_speed	=	_set_speed, \
+		.speed		=	_speed, \
+		.slaveaddr	=	_slaveaddr, \
+		.init_done	=	0, \
+		.hwadapnr	=	_hwadapnr, \
+		.name		=	#_name \
+};
+
+#define U_BOOT_I2C_ADAP_COMPLETE(_name, _init, _probe, _read, _write, \
+			_set_speed, _speed, _slaveaddr, _hwadapnr) \
+	ll_entry_declare(struct i2c_adapter, _name, i2c) = \
+	U_BOOT_I2C_MKENT_COMPLETE(_init, _probe, _read, _write, \
+		 _set_speed, _speed, _slaveaddr, _hwadapnr, _name);
+
+struct i2c_adapter *i2c_get_adapter(int index);
+
+#ifndef CONFIG_SYS_I2C_DIRECT_BUS
+struct i2c_mux {
+	int	id;
+	char	name[16];
+};
+
+struct i2c_next_hop {
+	struct i2c_mux		mux;
+	uint8_t		chip;
+	uint8_t		channel;
+};
+
+struct i2c_bus_hose {
+	int	adapter;
+	struct i2c_next_hop	next_hop[CONFIG_SYS_I2C_MAX_HOPS];
+};
+#define I2C_NULL_HOP	{{-1, ""}, 0, 0}
+extern struct i2c_bus_hose	i2c_bus[];
+
+#define I2C_ADAPTER(bus)	i2c_bus[bus].adapter
+#else
+#define I2C_ADAPTER(bus)	bus
+#endif
+#define	I2C_BUS			gd->cur_i2c_bus
+
+#define	I2C_ADAP_NR(bus)	i2c_get_adapter(I2C_ADAPTER(bus))
+#define	I2C_ADAP		I2C_ADAP_NR(gd->cur_i2c_bus)
+#define I2C_ADAP_HWNR		(I2C_ADAP->hwadapnr)
+
+#ifndef CONFIG_SYS_I2C_DIRECT_BUS
+#define I2C_MUX_PCA9540_ID	1
+#define I2C_MUX_PCA9540		{I2C_MUX_PCA9540_ID, "PCA9540B"}
+#define I2C_MUX_PCA9542_ID	2
+#define I2C_MUX_PCA9542		{I2C_MUX_PCA9542_ID, "PCA9542A"}
+#define I2C_MUX_PCA9544_ID	3
+#define I2C_MUX_PCA9544		{I2C_MUX_PCA9544_ID, "PCA9544A"}
+#define I2C_MUX_PCA9547_ID	4
+#define I2C_MUX_PCA9547		{I2C_MUX_PCA9547_ID, "PCA9547A"}
+#endif
+
 #ifndef I2C_SOFT_DECLARATIONS
 # if defined(CONFIG_MPC8260)
 #  define I2C_SOFT_DECLARATIONS volatile ioport_t *iop = ioport_addr((immap_t *)CONFIG_SYS_IMMR, I2C_PORT);
@@ -134,6 +218,104 @@ int i2x_mux_select_mux(int bus);
 int i2c_mux_ident_muxstring_f (uchar *buf);
 #endif
 
+#ifdef CONFIG_SYS_I2C
+/*
+ * Initialization, must be called once on start up, may be called
+ * repeatedly to change the speed and slave addresses.
+ */
+void i2c_init(unsigned int speed, int slaveaddr);
+#ifdef CONFIG_SYS_I2C_INIT_BOARD
+void i2c_init_board(void);
+#endif
+
+/*
+ * i2c_get_bus_num:
+ *
+ *  Returns index of currently active I2C bus.  Zero-based.
+ */
+unsigned int i2c_get_bus_num(void);
+
+/*
+ * i2c_set_bus_num:
+ *
+ *  Change the active I2C bus.  Subsequent read/write calls will
+ *  go to this one.
+ *
+ *	bus - bus index, zero based
+ *
+ *	Returns: 0 on success, not 0 on failure
+ *
+ */
+int i2c_set_bus_num(unsigned int bus);
+
+/*
+ * i2c_init_all():
+ *
+ * Initializes all I2C adapters in the system. All i2c_adap structures must
+ * be initialized beforehead with function pointers and data, including
+ * speed and slaveaddr. Returns 0 on success, non-0 on failure.
+ */
+void i2c_init_all(void);
+
+/*
+ * Probe the given I2C chip address.  Returns 0 if a chip responded,
+ * not 0 on failure.
+ */
+int i2c_probe(uint8_t chip);
+
+/*
+ * Read/Write interface:
+ *   chip:    I2C chip address, range 0..127
+ *   addr:    Memory (register) address within the chip
+ *   alen:    Number of bytes to use for addr (typically 1, 2 for larger
+ *              memories, 0 for register type devices with only one
+ *              register)
+ *   buffer:  Where to read/write the data
+ *   len:     How many bytes to read/write
+ *
+ *   Returns: 0 on success, not 0 on failure
+ */
+int i2c_read(uint8_t chip, unsigned int addr, int alen,
+				uint8_t *buffer, int len);
+
+int i2c_write(uint8_t chip, unsigned int addr, int alen,
+				uint8_t *buffer, int len);
+
+/*
+ * Utility routines to read/write registers.
+ */
+uint8_t i2c_reg_read(uint8_t addr, uint8_t reg);
+
+void i2c_reg_write(uint8_t addr, uint8_t reg, uint8_t val);
+
+/*
+ * i2c_set_bus_speed:
+ *
+ *  Change the speed of the active I2C bus
+ *
+ *	speed - bus speed in Hz
+ *
+ *	Returns: new bus speed
+ *
+ */
+unsigned int i2c_set_bus_speed(unsigned int speed);
+
+/*
+ * i2c_get_bus_speed:
+ *
+ *  Returns speed of currently active I2C bus in Hz
+ */
+
+unsigned int i2c_get_bus_speed(void);
+
+/*
+ * i2c_reloc_fixup:
+ *
+ * Adjusts I2C pointers after U-Boot is relocated to DRAM
+ */
+void i2c_reloc_fixup(void);
+#else
+
 /*
  * Probe the given I2C chip address.  Returns 0 if a chip responded,
  * not 0 on failure.
@@ -235,6 +417,21 @@ int i2c_set_bus_speed(unsigned int);
  */
 
 unsigned int i2c_get_bus_speed(void);
+#endif /* CONFIG_SYS_I2C */
+
+/*
+ * only for backwardcompatibility, should go away if we switched
+ * completely to new multibus support.
+ */
+#if defined(CONFIG_SYS_I2C) || defined(CONFIG_I2C_MULTI_BUS)
+# if !defined(CONFIG_SYS_MAX_I2C_BUS)
+#  define CONFIG_SYS_MAX_I2C_BUS		2
+# endif
+# define I2C_MULTI_BUS				0
+#else
+# define CONFIG_SYS_MAX_I2C_BUS		1
+# define I2C_MULTI_BUS				0
+#endif
 
 /* NOTE: These two functions MUST be always_inline to avoid code growth! */
 static inline unsigned int I2C_GET_BUS(void) __attribute__((always_inline));