summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorRussell King <rmk@dyn-67.arm.linux.org.uk>2007-03-04 20:40:50 +0000
committerRussell King <rmk+kernel@arm.linux.org.uk>2007-03-04 20:40:50 +0000
commit8d91cbad8e6fd5b37bf584740f134508709ba035 (patch)
tree1ce49dd94842d413597f4fb4e387584ce481d8a6
parent23d046f43a05155e050a68f3ad1f19b672713374 (diff)
downloadlinux-stable-8d91cbad8e6fd5b37bf584740f134508709ba035.tar.gz
linux-stable-8d91cbad8e6fd5b37bf584740f134508709ba035.tar.bz2
linux-stable-8d91cbad8e6fd5b37bf584740f134508709ba035.zip
[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>
-rw-r--r--drivers/acorn/char/Makefile1
-rw-r--r--drivers/acorn/char/i2c.c368
-rw-r--r--drivers/acorn/char/pcf8583.c284
-rw-r--r--drivers/acorn/char/pcf8583.h41
-rw-r--r--drivers/i2c/busses/Kconfig10
-rw-r--r--drivers/i2c/busses/Makefile1
-rw-r--r--drivers/i2c/busses/i2c-acorn.c97
7 files changed, 108 insertions, 694 deletions
diff --git a/drivers/acorn/char/Makefile b/drivers/acorn/char/Makefile
index 2fa9a8bf48a0..d006c9f168d2 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 d276fd14d63a..000000000000
--- 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 9b49f316ae92..000000000000
--- 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 847f7fdb8763..000000000000
--- 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 4d44a2db29dd..fb19dbb31e42 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 03505aa44bbf..290b54018354 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 000000000000..09bd7f40b90c
--- /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);