241 lines
6.5 KiB
C
241 lines
6.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* i2c-nforce2-s4985.c - i2c-nforce2 extras for the Tyan S4985 motherboard
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*
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* Copyright (C) 2008 Jean Delvare <jdelvare@suse.de>
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*/
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/*
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* We select the channels by sending commands to the Philips
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* PCA9556 chip at I2C address 0x18. The main adapter is used for
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* the non-multiplexed part of the bus, and 4 virtual adapters
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* are defined for the multiplexed addresses: 0x50-0x53 (memory
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* module EEPROM) located on channels 1-4. We define one virtual
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* adapter per CPU, which corresponds to one multiplexed channel:
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* CPU0: virtual adapter 1, channel 1
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* CPU1: virtual adapter 2, channel 2
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* CPU2: virtual adapter 3, channel 3
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* CPU3: virtual adapter 4, channel 4
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/i2c.h>
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#include <linux/mutex.h>
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extern struct i2c_adapter *nforce2_smbus;
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static struct i2c_adapter *s4985_adapter;
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static struct i2c_algorithm *s4985_algo;
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/* Wrapper access functions for multiplexed SMBus */
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static DEFINE_MUTEX(nforce2_lock);
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static s32 nforce2_access_virt0(struct i2c_adapter *adap, u16 addr,
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unsigned short flags, char read_write,
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u8 command, int size,
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union i2c_smbus_data *data)
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{
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int error;
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/* We exclude the multiplexed addresses */
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if ((addr & 0xfc) == 0x50 || (addr & 0xfc) == 0x30
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|| addr == 0x18)
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return -ENXIO;
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mutex_lock(&nforce2_lock);
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error = nforce2_smbus->algo->smbus_xfer(adap, addr, flags, read_write,
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command, size, data);
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mutex_unlock(&nforce2_lock);
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return error;
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}
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/* We remember the last used channels combination so as to only switch
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channels when it is really needed. This greatly reduces the SMBus
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overhead, but also assumes that nobody will be writing to the PCA9556
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in our back. */
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static u8 last_channels;
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static inline s32 nforce2_access_channel(struct i2c_adapter *adap, u16 addr,
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unsigned short flags, char read_write,
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u8 command, int size,
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union i2c_smbus_data *data,
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u8 channels)
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{
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int error;
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/* We exclude the non-multiplexed addresses */
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if ((addr & 0xfc) != 0x50 && (addr & 0xfc) != 0x30)
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return -ENXIO;
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mutex_lock(&nforce2_lock);
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if (last_channels != channels) {
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union i2c_smbus_data mplxdata;
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mplxdata.byte = channels;
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error = nforce2_smbus->algo->smbus_xfer(adap, 0x18, 0,
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I2C_SMBUS_WRITE, 0x01,
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I2C_SMBUS_BYTE_DATA,
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&mplxdata);
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if (error)
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goto UNLOCK;
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last_channels = channels;
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}
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error = nforce2_smbus->algo->smbus_xfer(adap, addr, flags, read_write,
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command, size, data);
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UNLOCK:
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mutex_unlock(&nforce2_lock);
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return error;
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}
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static s32 nforce2_access_virt1(struct i2c_adapter *adap, u16 addr,
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unsigned short flags, char read_write,
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u8 command, int size,
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union i2c_smbus_data *data)
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{
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/* CPU0: channel 1 enabled */
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return nforce2_access_channel(adap, addr, flags, read_write, command,
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size, data, 0x02);
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}
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static s32 nforce2_access_virt2(struct i2c_adapter *adap, u16 addr,
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unsigned short flags, char read_write,
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u8 command, int size,
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union i2c_smbus_data *data)
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{
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/* CPU1: channel 2 enabled */
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return nforce2_access_channel(adap, addr, flags, read_write, command,
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size, data, 0x04);
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}
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static s32 nforce2_access_virt3(struct i2c_adapter *adap, u16 addr,
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unsigned short flags, char read_write,
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u8 command, int size,
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union i2c_smbus_data *data)
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{
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/* CPU2: channel 3 enabled */
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return nforce2_access_channel(adap, addr, flags, read_write, command,
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size, data, 0x08);
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}
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static s32 nforce2_access_virt4(struct i2c_adapter *adap, u16 addr,
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unsigned short flags, char read_write,
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u8 command, int size,
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union i2c_smbus_data *data)
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{
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/* CPU3: channel 4 enabled */
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return nforce2_access_channel(adap, addr, flags, read_write, command,
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size, data, 0x10);
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}
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static int __init nforce2_s4985_init(void)
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{
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int i, error;
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union i2c_smbus_data ioconfig;
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if (!nforce2_smbus)
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return -ENODEV;
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/* Configure the PCA9556 multiplexer */
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ioconfig.byte = 0x00; /* All I/O to output mode */
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error = i2c_smbus_xfer(nforce2_smbus, 0x18, 0, I2C_SMBUS_WRITE, 0x03,
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I2C_SMBUS_BYTE_DATA, &ioconfig);
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if (error) {
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dev_err(&nforce2_smbus->dev, "PCA9556 configuration failed\n");
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error = -EIO;
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goto ERROR0;
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}
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/* Unregister physical bus */
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i2c_del_adapter(nforce2_smbus);
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printk(KERN_INFO "Enabling SMBus multiplexing for Tyan S4985\n");
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/* Define the 5 virtual adapters and algorithms structures */
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s4985_adapter = kcalloc(5, sizeof(struct i2c_adapter), GFP_KERNEL);
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if (!s4985_adapter) {
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error = -ENOMEM;
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goto ERROR1;
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}
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s4985_algo = kcalloc(5, sizeof(struct i2c_algorithm), GFP_KERNEL);
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if (!s4985_algo) {
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error = -ENOMEM;
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goto ERROR2;
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}
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/* Fill in the new structures */
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s4985_algo[0] = *(nforce2_smbus->algo);
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s4985_algo[0].smbus_xfer = nforce2_access_virt0;
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s4985_adapter[0] = *nforce2_smbus;
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s4985_adapter[0].algo = s4985_algo;
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s4985_adapter[0].dev.parent = nforce2_smbus->dev.parent;
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for (i = 1; i < 5; i++) {
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s4985_algo[i] = *(nforce2_smbus->algo);
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s4985_adapter[i] = *nforce2_smbus;
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snprintf(s4985_adapter[i].name, sizeof(s4985_adapter[i].name),
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"SMBus nForce2 adapter (CPU%d)", i - 1);
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s4985_adapter[i].algo = s4985_algo + i;
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s4985_adapter[i].dev.parent = nforce2_smbus->dev.parent;
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}
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s4985_algo[1].smbus_xfer = nforce2_access_virt1;
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s4985_algo[2].smbus_xfer = nforce2_access_virt2;
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s4985_algo[3].smbus_xfer = nforce2_access_virt3;
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s4985_algo[4].smbus_xfer = nforce2_access_virt4;
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/* Register virtual adapters */
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for (i = 0; i < 5; i++) {
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error = i2c_add_adapter(s4985_adapter + i);
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if (error) {
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printk(KERN_ERR "i2c-nforce2-s4985: "
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"Virtual adapter %d registration "
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"failed, module not inserted\n", i);
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for (i--; i >= 0; i--)
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i2c_del_adapter(s4985_adapter + i);
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goto ERROR3;
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}
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}
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return 0;
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ERROR3:
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kfree(s4985_algo);
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s4985_algo = NULL;
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ERROR2:
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kfree(s4985_adapter);
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s4985_adapter = NULL;
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ERROR1:
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/* Restore physical bus */
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i2c_add_adapter(nforce2_smbus);
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ERROR0:
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return error;
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}
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static void __exit nforce2_s4985_exit(void)
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{
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if (s4985_adapter) {
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int i;
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for (i = 0; i < 5; i++)
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i2c_del_adapter(s4985_adapter+i);
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kfree(s4985_adapter);
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s4985_adapter = NULL;
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}
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kfree(s4985_algo);
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s4985_algo = NULL;
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/* Restore physical bus */
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if (i2c_add_adapter(nforce2_smbus))
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printk(KERN_ERR "i2c-nforce2-s4985: "
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"Physical bus restoration failed\n");
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}
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MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
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MODULE_DESCRIPTION("S4985 SMBus multiplexing");
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MODULE_LICENSE("GPL");
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module_init(nforce2_s4985_init);
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module_exit(nforce2_s4985_exit);
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