[ARM] Acorn: move the i2c bus driver into drivers/i2c

Move the Acorn IOC/IOMD I2C bus driver from drivers/i2c, strip
out the reminants of the platform specific parts of the old
PCF8583 RTC code, and remove the old obsolete PCF8583 driver.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

7 files changed, 108 insertions, 694 deletions

diff --git a/drivers/acorn/char/Makefile b/drivers/acorn/char/Makefile
index 2fa9a8bf48a..d006c9f168d 100644
--- a/drivers/acorn/char/Makefile
+++ b/drivers/acorn/char/Makefile
@@ -2,5 +2,4 @@
 # Makefile for the acorn character device drivers.
 #
 
-obj-$(CONFIG_ARCH_ACORN)	+= i2c.o pcf8583.o
 obj-$(CONFIG_L7200_KEYB)	+= defkeymap-l7200.o keyb_l7200.o
diff --git a/drivers/acorn/char/i2c.c b/drivers/acorn/char/i2c.c
deleted file mode 100644
index d276fd14d63..00000000000
--- a/drivers/acorn/char/i2c.c
+++ /dev/null
@@ -1,368 +0,0 @@
-/*
- *  linux/drivers/acorn/char/i2c.c
- *
- *  Copyright (C) 2000 Russell King
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- *  ARM IOC/IOMD i2c driver.
- *
- *  On Acorn machines, the following i2c devices are on the bus:
- *	- PCF8583 real time clock & static RAM
- */
-#include <linux/capability.h>
-#include <linux/init.h>
-#include <linux/time.h>
-#include <linux/miscdevice.h>
-#include <linux/rtc.h>
-#include <linux/i2c.h>
-#include <linux/i2c-algo-bit.h>
-#include <linux/fs.h>
-
-#include <asm/hardware.h>
-#include <asm/io.h>
-#include <asm/hardware/ioc.h>
-#include <asm/system.h>
-#include <asm/uaccess.h>
-
-#include "pcf8583.h"
-
-extern int (*set_rtc)(void);
-
-static struct i2c_client *rtc_client;
-static const unsigned char days_in_mon[] = 
-	{ 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
-
-#define CMOS_CHECKSUM	(63)
-
-/*
- * Acorn machines store the year in the static RAM at
- * location 128.
- */
-#define CMOS_YEAR	(64 + 128)
-
-static inline int rtc_command(int cmd, void *data)
-{
-	int ret = -EIO;
-
-	if (rtc_client)
-		ret = rtc_client->driver->command(rtc_client, cmd, data);
-
-	return ret;
-}
-
-/*
- * Update the century + year bytes in the CMOS RAM, ensuring
- * that the check byte is correctly adjusted for the change.
- */
-static int rtc_update_year(unsigned int new_year)
-{
-	unsigned char yr[2], chk;
-	struct mem cmos_year  = { CMOS_YEAR, sizeof(yr), yr };
-	struct mem cmos_check = { CMOS_CHECKSUM, 1, &chk };
-	int ret;
-
-	ret = rtc_command(MEM_READ, &cmos_check);
-	if (ret)
-		goto out;
-	ret = rtc_command(MEM_READ, &cmos_year);
-	if (ret)
-		goto out;
-
-	chk -= yr[1] + yr[0];
-
-	yr[1] = new_year / 100;
-	yr[0] = new_year % 100;
-
-	chk += yr[1] + yr[0];
-
-	ret = rtc_command(MEM_WRITE, &cmos_year);
-	if (ret == 0)
-		ret = rtc_command(MEM_WRITE, &cmos_check);
- out:
-	return ret;
-}
-
-/*
- * Read the current RTC time and date, and update xtime.
- */
-static void get_rtc_time(struct rtc_tm *rtctm, unsigned int *year)
-{
-	unsigned char ctrl, yr[2];
-	struct mem rtcmem = { CMOS_YEAR, sizeof(yr), yr };
-	int real_year, year_offset;
-
-	/*
-	 * Ensure that the RTC is running.
-	 */
-	rtc_command(RTC_GETCTRL, &ctrl);
-	if (ctrl & 0xc0) {
-		unsigned char new_ctrl = ctrl & ~0xc0;
-
-		printk(KERN_WARNING "RTC: resetting control %02x -> %02x\n",
-		       ctrl, new_ctrl);
-
-		rtc_command(RTC_SETCTRL, &new_ctrl);
-	}
-
-	if (rtc_command(RTC_GETDATETIME, rtctm) ||
-	    rtc_command(MEM_READ, &rtcmem))
-		return;
-
-	real_year = yr[0];
-
-	/*
-	 * The RTC year holds the LSB two bits of the current
-	 * year, which should reflect the LSB two bits of the
-	 * CMOS copy of the year.  Any difference indicates
-	 * that we have to correct the CMOS version.
-	 */
-	year_offset = rtctm->year_off - (real_year & 3);
-	if (year_offset < 0)
-		/*
-		 * RTC year wrapped.  Adjust it appropriately.
-		 */
-		year_offset += 4;
-
-	*year = real_year + year_offset + yr[1] * 100;
-}
-
-static int set_rtc_time(struct rtc_tm *rtctm, unsigned int year)
-{
-	unsigned char leap;
-	int ret;
-
-	leap = (!(year % 4) && (year % 100)) || !(year % 400);
-
-	if (rtctm->mon > 12 || rtctm->mon == 0 || rtctm->mday == 0)
-		return -EINVAL;
-
-	if (rtctm->mday > (days_in_mon[rtctm->mon] + (rtctm->mon == 2 && leap)))
-		return -EINVAL;
-
-	if (rtctm->hours >= 24 || rtctm->mins >= 60 || rtctm->secs >= 60)
-		return -EINVAL;
-
-	/*
-	 * The RTC's own 2-bit year must reflect the least
-	 * significant two bits of the CMOS year.
-	 */
-	rtctm->year_off = (year % 100) & 3;
-
-	ret = rtc_command(RTC_SETDATETIME, rtctm);
-	if (ret == 0)
-		ret = rtc_update_year(year);
-
-	return ret;
-}
-
-/*
- * Set the RTC time only.  Note that
- * we do not touch the date.
- */
-static int k_set_rtc_time(void)
-{
-	struct rtc_tm new_rtctm, old_rtctm;
-	unsigned long nowtime = xtime.tv_sec;
-
-	if (rtc_command(RTC_GETDATETIME, &old_rtctm))
-		return 0;
-
-	new_rtctm.cs    = xtime.tv_nsec / 10000000;
-	new_rtctm.secs  = nowtime % 60;	nowtime /= 60;
-	new_rtctm.mins  = nowtime % 60;	nowtime /= 60;
-	new_rtctm.hours = nowtime % 24;
-
-	/*
-	 * avoid writing when we're going to change the day
-	 * of the month.  We will retry in the next minute.
-	 * This basically means that if the RTC must not drift
-	 * by more than 1 minute in 11 minutes.
-	 *
-	 * [ rtc: 1/1/2000 23:58:00, real 2/1/2000 00:01:00,
-	 *   rtc gets set to 1/1/2000 00:01:00 ]
-	 */
-	if ((old_rtctm.hours == 23 && old_rtctm.mins == 59) ||
-	    (new_rtctm.hours == 23 && new_rtctm.mins == 59))
-		return 1;
-
-	return rtc_command(RTC_SETTIME, &new_rtctm);
-}
-
-static int rtc_ioctl(struct inode *inode, struct file *file,
-		     unsigned int cmd, unsigned long arg)
-{
-	unsigned int year;
-	struct rtc_time rtctm;
-	struct rtc_tm rtc_raw;
-
-	switch (cmd) {
-	case RTC_ALM_READ:
-	case RTC_ALM_SET:
-		break;
-
-	case RTC_RD_TIME:
-		memset(&rtctm, 0, sizeof(struct rtc_time));
-		get_rtc_time(&rtc_raw, &year);
-		rtctm.tm_sec  = rtc_raw.secs;
-		rtctm.tm_min  = rtc_raw.mins;
-		rtctm.tm_hour = rtc_raw.hours;
-		rtctm.tm_mday = rtc_raw.mday;
-		rtctm.tm_mon  = rtc_raw.mon - 1; /* month starts at 0 */
-		rtctm.tm_year = year - 1900; /* starts at 1900 */
-		return copy_to_user((void *)arg, &rtctm, sizeof(rtctm))
-				 ? -EFAULT : 0;
-
-	case RTC_SET_TIME:
-		if (!capable(CAP_SYS_TIME))
-			return -EACCES;
-
-		if (copy_from_user(&rtctm, (void *)arg, sizeof(rtctm)))
-			return -EFAULT;
-		rtc_raw.secs     = rtctm.tm_sec;
-		rtc_raw.mins     = rtctm.tm_min;
-		rtc_raw.hours    = rtctm.tm_hour;
-		rtc_raw.mday     = rtctm.tm_mday;
-		rtc_raw.mon      = rtctm.tm_mon + 1;
-		year             = rtctm.tm_year + 1900;
-		return set_rtc_time(&rtc_raw, year);
-		break;
-
-	case RTC_EPOCH_READ:
-		return put_user(1900, (unsigned long *)arg);
-
-	}
-	return -EINVAL;
-}
-
-static const struct file_operations rtc_fops = {
-	.ioctl	= rtc_ioctl,
-};
-
-static struct miscdevice rtc_dev = {
-	.minor	= RTC_MINOR,
-	.name	= "rtc",
-	.fops	= &rtc_fops,
-};
-
-/* IOC / IOMD i2c driver */
-
-#define FORCE_ONES	0xdc
-#define SCL		0x02
-#define SDA		0x01
-
-/*
- * We must preserve all non-i2c output bits in IOC_CONTROL.
- * Note also that we need to preserve the value of SCL and
- * SDA outputs as well (which may be different from the
- * values read back from IOC_CONTROL).
- */
-static u_int force_ones;
-
-static void ioc_setscl(void *data, int state)
-{
-	u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
-	u_int ones = force_ones;
-
-	if (state)
-		ones |= SCL;
-	else
-		ones &= ~SCL;
-
-	force_ones = ones;
-
- 	ioc_writeb(ioc_control | ones, IOC_CONTROL);
-}
-
-static void ioc_setsda(void *data, int state)
-{
-	u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
-	u_int ones = force_ones;
-
-	if (state)
-		ones |= SDA;
-	else
-		ones &= ~SDA;
-
-	force_ones = ones;
-
- 	ioc_writeb(ioc_control | ones, IOC_CONTROL);
-}
-
-static int ioc_getscl(void *data)
-{
-	return (ioc_readb(IOC_CONTROL) & SCL) != 0;
-}
-
-static int ioc_getsda(void *data)
-{
-	return (ioc_readb(IOC_CONTROL) & SDA) != 0;
-}
-
-static struct i2c_algo_bit_data ioc_data = {
-	.setsda		= ioc_setsda,
-	.setscl		= ioc_setscl,
-	.getsda		= ioc_getsda,
-	.getscl		= ioc_getscl,
-	.udelay		= 80,
-	.timeout	= 100
-};
-
-static int ioc_client_reg(struct i2c_client *client)
-{
-	if (client->driver->id == I2C_DRIVERID_PCF8583 &&
-	    client->addr == 0x50) {
-		struct rtc_tm rtctm;
-		unsigned int year;
-		struct timespec tv;
-
-		rtc_client = client;
-		get_rtc_time(&rtctm, &year);
-
-		tv.tv_nsec = rtctm.cs * 10000000;
-		tv.tv_sec  = mktime(year, rtctm.mon, rtctm.mday,
-				    rtctm.hours, rtctm.mins, rtctm.secs);
-		do_settimeofday(&tv);
-		set_rtc = k_set_rtc_time;
-	}
-
-	return 0;
-}
-
-static int ioc_client_unreg(struct i2c_client *client)
-{
-	if (client == rtc_client) {
-		set_rtc = NULL;
-		rtc_client = NULL;
-	}
-
-	return 0;
-}
-
-static struct i2c_adapter ioc_ops = {
-	.id			= I2C_HW_B_IOC,
-	.algo_data		= &ioc_data,
-	.client_register	= ioc_client_reg,
-	.client_unregister	= ioc_client_unreg,
-};
-
-static int __init i2c_ioc_init(void)
-{
-	int ret;
-
-	force_ones = FORCE_ONES | SCL | SDA;
-
-	ret = i2c_bit_add_bus(&ioc_ops);
-
-	if (ret >= 0){
-		ret = misc_register(&rtc_dev);
-		if(ret < 0)
-			i2c_del_adapter(&ioc_ops);
-	}
-
-	return ret;
-}
-
-__initcall(i2c_ioc_init);
diff --git a/drivers/acorn/char/pcf8583.c b/drivers/acorn/char/pcf8583.c
deleted file mode 100644
index 9b49f316ae9..00000000000
--- a/drivers/acorn/char/pcf8583.c
+++ /dev/null
@@ -1,284 +0,0 @@
-/*
- *  linux/drivers/acorn/char/pcf8583.c
- *
- *  Copyright (C) 2000 Russell King
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- *  Driver for PCF8583 RTC & RAM chip
- */
-#include <linux/module.h>
-#include <linux/i2c.h>
-#include <linux/slab.h>
-#include <linux/string.h>
-#include <linux/mc146818rtc.h>
-#include <linux/init.h>
-#include <linux/errno.h>
-#include <linux/bcd.h>
-
-#include "pcf8583.h"
-
-static struct i2c_driver pcf8583_driver;
-
-static unsigned short ignore[] = { I2C_CLIENT_END };
-static unsigned short normal_addr[] = { 0x50, I2C_CLIENT_END };
-static unsigned short *forces[] = { NULL };
-
-static struct i2c_client_address_data addr_data = {
-	.normal_i2c		= normal_addr,
-	.probe			= ignore,
-	.ignore			= ignore,
-	.forces			= forces,
-};
-
-#define set_ctrl(x, v) i2c_set_clientdata(x, (void *)(unsigned int)(v))
-#define get_ctrl(x)    ((unsigned int)i2c_get_clientdata(x))
-
-static int
-pcf8583_attach(struct i2c_adapter *adap, int addr, int kind)
-{
-	struct i2c_client *c;
-	unsigned char buf[1], ad[1] = { 0 };
-	struct i2c_msg msgs[2] = {
-		{
-			.addr = addr,
-			.flags = 0,
-			.len = 1,
-			.buf = ad,
-		}, {
-			.addr = addr,
-			.flags = I2C_M_RD,
-			.len = 1,
-			.buf = buf,
-		}
-	};
-
-	c = kmalloc(sizeof(*c), GFP_KERNEL);
-	if (!c)
-		return -ENOMEM;
-
-	memset(c, 0, sizeof(*c));
-	c->addr		= addr;
-	c->adapter	= adap;
-	c->driver	= &pcf8583_driver;
-
-	if (i2c_transfer(c->adapter, msgs, 2) == 2)
-		set_ctrl(c, buf[0]);
-
-	return i2c_attach_client(c);
-}
-
-static int
-pcf8583_probe(struct i2c_adapter *adap)
-{
-	return i2c_probe(adap, &addr_data, pcf8583_attach);
-}
-
-static int
-pcf8583_detach(struct i2c_client *client)
-{
-	i2c_detach_client(client);
-	kfree(client);
-	return 0;
-}
-
-static int
-pcf8583_get_datetime(struct i2c_client *client, struct rtc_tm *dt)
-{
-	unsigned char buf[8], addr[1] = { 1 };
-	struct i2c_msg msgs[2] = {
-		{
-			.addr = client->addr,
-			.flags = 0,
-			.len = 1,
-			.buf = addr,
-		}, {
-			.addr = client->addr,
-			.flags = I2C_M_RD,
-			.len = 6,
-			.buf = buf,
-		}
-	};
-	int ret = -EIO;
-
-	memset(buf, 0, sizeof(buf));
-
-	ret = i2c_transfer(client->adapter, msgs, 2);
-	if (ret == 2) {
-		dt->year_off = buf[4] >> 6;
-		dt->wday     = buf[5] >> 5;
-
-		buf[4] &= 0x3f;
-		buf[5] &= 0x1f;
-
-		dt->cs       = BCD_TO_BIN(buf[0]);
-		dt->secs     = BCD_TO_BIN(buf[1]);
-		dt->mins     = BCD_TO_BIN(buf[2]);
-		dt->hours    = BCD_TO_BIN(buf[3]);
-		dt->mday     = BCD_TO_BIN(buf[4]);
-		dt->mon      = BCD_TO_BIN(buf[5]);
-
-		ret = 0;
-	}
-
-	return ret;
-}
-
-static int
-pcf8583_set_datetime(struct i2c_client *client, struct rtc_tm *dt, int datetoo)
-{
-	unsigned char buf[8];
-	int ret, len = 6;
-
-	buf[0] = 0;
-	buf[1] = get_ctrl(client) | 0x80;
-	buf[2] = BIN_TO_BCD(dt->cs);
-	buf[3] = BIN_TO_BCD(dt->secs);
-	buf[4] = BIN_TO_BCD(dt->mins);
-	buf[5] = BIN_TO_BCD(dt->hours);
-
-	if (datetoo) {
-		len = 8;
-		buf[6] = BIN_TO_BCD(dt->mday) | (dt->year_off << 6);
-		buf[7] = BIN_TO_BCD(dt->mon)  | (dt->wday << 5);
-	}
-
-	ret = i2c_master_send(client, (char *)buf, len);
-	if (ret == len)
-		ret = 0;
-
-	buf[1] = get_ctrl(client);
-	i2c_master_send(client, (char *)buf, 2);
-
-	return ret;
-}
-
-static int
-pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl)
-{
-	*ctrl = get_ctrl(client);
-	return 0;
-}
-
-static int
-pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl)
-{
-	unsigned char buf[2];
-
-	buf[0] = 0;
-	buf[1] = *ctrl;
-	set_ctrl(client, *ctrl);
-
-	return i2c_master_send(client, (char *)buf, 2);
-}
-
-static int
-pcf8583_read_mem(struct i2c_client *client, struct mem *mem)
-{
-	unsigned char addr[1];
-	struct i2c_msg msgs[2] = {
-		{
-			.addr = client->addr,
-			.flags = 0,
-			.len = 1,
-			.buf = addr,
-		}, {
-			.addr = client->addr,
-			.flags = I2C_M_RD,
-			.len = mem->nr,
-			.buf = mem->data,
-		}
-	};
-
-	if (mem->loc < 8)
-		return -EINVAL;
-
-	addr[0] = mem->loc;
-
-	return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO;
-}
-
-static int
-pcf8583_write_mem(struct i2c_client *client, struct mem *mem)
-{
-	unsigned char addr[1];
-	struct i2c_msg msgs[2] = {
-		{
-			.addr = client->addr,
-			.flags = 0,
-			.len = 1,
-			.buf = addr,
-		}, {
-			.addr = client->addr,
-			.flags = I2C_M_NOSTART,
-			.len = mem->nr,
-			.buf = mem->data,
-		}
-	};
-
-	if (mem->loc < 8)
-		return -EINVAL;
-
-	addr[0] = mem->loc;
-
-	return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO;
-}
-
-static int
-pcf8583_command(struct i2c_client *client, unsigned int cmd, void *arg)
-{
-	switch (cmd) {
-	case RTC_GETDATETIME:
-		return pcf8583_get_datetime(client, arg);
-		
-	case RTC_SETTIME:
-		return pcf8583_set_datetime(client, arg, 0);
-
-	case RTC_SETDATETIME:
-		return pcf8583_set_datetime(client, arg, 1);
-
-	case RTC_GETCTRL:
-		return pcf8583_get_ctrl(client, arg);
-
-	case RTC_SETCTRL:
-		return pcf8583_set_ctrl(client, arg);
-
-	case MEM_READ:
-		return pcf8583_read_mem(client, arg);
-
-	case MEM_WRITE:
-		return pcf8583_write_mem(client, arg);
-
-	default:
-		return -EINVAL;
-	}
-}
-
-static struct i2c_driver pcf8583_driver = {
-	.driver = {
-		.name	= "PCF8583",
-	},
-	.id		= I2C_DRIVERID_PCF8583,
-	.attach_adapter	= pcf8583_probe,
-	.detach_client	= pcf8583_detach,
-	.command	= pcf8583_command
-};
-
-static __init int pcf8583_init(void)
-{
-	return i2c_add_driver(&pcf8583_driver);
-}
-
-static __exit void pcf8583_exit(void)
-{
-	i2c_del_driver(&pcf8583_driver);
-}
-
-module_init(pcf8583_init);
-module_exit(pcf8583_exit);
-
-MODULE_AUTHOR("Russell King");
-MODULE_DESCRIPTION("PCF8583 I2C RTC driver");
-MODULE_LICENSE("GPL");
diff --git a/drivers/acorn/char/pcf8583.h b/drivers/acorn/char/pcf8583.h
deleted file mode 100644
index 847f7fdb876..00000000000
--- a/drivers/acorn/char/pcf8583.h
+++ /dev/null
@@ -1,41 +0,0 @@
-/*
- *  linux/drivers/acorn/char/pcf8583.h
- *
- *  Copyright (C) 2000 Russell King
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
-struct rtc_tm {
-	unsigned char	cs;
-	unsigned char	secs;
-	unsigned char	mins;
-	unsigned char	hours;
-	unsigned char	mday;
-	unsigned char	mon;
-	unsigned char	year_off;
-	unsigned char	wday;
-};
-
-struct mem {
-	unsigned int	loc;
-	unsigned int	nr;
-	unsigned char	*data;
-};
-
-#define RTC_GETDATETIME	0
-#define RTC_SETTIME	1
-#define RTC_SETDATETIME	2
-#define RTC_GETCTRL	3
-#define RTC_SETCTRL	4
-#define MEM_READ	5
-#define MEM_WRITE	6
-
-#define CTRL_STOP	0x80
-#define CTRL_HOLD	0x40
-#define CTRL_32KHZ	0x00
-#define CTRL_MASK	0x08
-#define CTRL_ALARMEN	0x04
-#define CTRL_ALARM	0x02
-#define CTRL_TIMER	0x01
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 4d44a2db29d..fb19dbb31e4 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -495,6 +495,16 @@ config I2C_VERSATILE
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-versatile.
 
+config I2C_ACORN
+	bool "Acorn IOC/IOMD I2C bus support"
+	depends on I2C && ARCH_ACORN
+	default y
+	select I2C_ALGOBIT
+	help
+	  Say yes if you want to support the I2C bus on Acorn platforms.
+
+	  If you don't know, say Y.
+
 config I2C_VIA
 	tristate "VIA 82C586B"
 	depends on I2C && PCI && EXPERIMENTAL
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 03505aa44bb..290b5401835 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -42,6 +42,7 @@ obj-$(CONFIG_I2C_SIS630)	+= i2c-sis630.o
 obj-$(CONFIG_I2C_SIS96X)	+= i2c-sis96x.o
 obj-$(CONFIG_I2C_STUB)		+= i2c-stub.o
 obj-$(CONFIG_I2C_VERSATILE)	+= i2c-versatile.o
+obj-$(CONFIG_I2C_ACORN)		+= i2c-acorn.o
 obj-$(CONFIG_I2C_VIA)		+= i2c-via.o
 obj-$(CONFIG_I2C_VIAPRO)	+= i2c-viapro.o
 obj-$(CONFIG_I2C_VOODOO3)	+= i2c-voodoo3.o
diff --git a/drivers/i2c/busses/i2c-acorn.c b/drivers/i2c/busses/i2c-acorn.c
new file mode 100644
index 00000000000..09bd7f40b90
--- /dev/null
+++ b/drivers/i2c/busses/i2c-acorn.c
@@ -0,0 +1,97 @@
+/*
+ *  linux/drivers/acorn/char/i2c.c
+ *
+ *  Copyright (C) 2000 Russell King
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ *  ARM IOC/IOMD i2c driver.
+ *
+ *  On Acorn machines, the following i2c devices are on the bus:
+ *	- PCF8583 real time clock & static RAM
+ */
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/i2c-algo-bit.h>
+
+#include <asm/hardware.h>
+#include <asm/io.h>
+#include <asm/hardware/ioc.h>
+#include <asm/system.h>
+
+#define FORCE_ONES	0xdc
+#define SCL		0x02
+#define SDA		0x01
+
+/*
+ * We must preserve all non-i2c output bits in IOC_CONTROL.
+ * Note also that we need to preserve the value of SCL and
+ * SDA outputs as well (which may be different from the
+ * values read back from IOC_CONTROL).
+ */
+static u_int force_ones;
+
+static void ioc_setscl(void *data, int state)
+{
+	u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
+	u_int ones = force_ones;
+
+	if (state)
+		ones |= SCL;
+	else
+		ones &= ~SCL;
+
+	force_ones = ones;
+
+ 	ioc_writeb(ioc_control | ones, IOC_CONTROL);
+}
+
+static void ioc_setsda(void *data, int state)
+{
+	u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
+	u_int ones = force_ones;
+
+	if (state)
+		ones |= SDA;
+	else
+		ones &= ~SDA;
+
+	force_ones = ones;
+
+ 	ioc_writeb(ioc_control | ones, IOC_CONTROL);
+}
+
+static int ioc_getscl(void *data)
+{
+	return (ioc_readb(IOC_CONTROL) & SCL) != 0;
+}
+
+static int ioc_getsda(void *data)
+{
+	return (ioc_readb(IOC_CONTROL) & SDA) != 0;
+}
+
+static struct i2c_algo_bit_data ioc_data = {
+	.setsda		= ioc_setsda,
+	.setscl		= ioc_setscl,
+	.getsda		= ioc_getsda,
+	.getscl		= ioc_getscl,
+	.udelay		= 80,
+	.timeout	= 100
+};
+
+static struct i2c_adapter ioc_ops = {
+	.id			= I2C_HW_B_IOC,
+	.algo_data		= &ioc_data,
+};
+
+static int __init i2c_ioc_init(void)
+{
+	force_ones = FORCE_ONES | SCL | SDA;
+
+	return i2c_bit_add_bus(&ioc_ops);
+}
+
+__initcall(i2c_ioc_init);