3 files changed, 108 insertions, 0 deletions

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);