linux/drivers/i2c/busses/i2c-nforce2-s4985.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * i2c-nforce2-s4985.c - i2c-nforce2 extras for the Tyan S4985 motherboard
 *
 * Copyright (C) 2008 Jean Delvare <[email protected]>
 */

/*
 * We select the channels by sending commands to the Philips
 * PCA9556 chip at I2C address 0x18. The main adapter is used for
 * the non-multiplexed part of the bus, and 4 virtual adapters
 * are defined for the multiplexed addresses: 0x50-0x53 (memory
 * module EEPROM) located on channels 1-4. We define one virtual
 * adapter per CPU, which corresponds to one multiplexed channel:
 *   CPU0: virtual adapter 1, channel 1
 *   CPU1: virtual adapter 2, channel 2
 *   CPU2: virtual adapter 3, channel 3
 *   CPU3: virtual adapter 4, channel 4
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/mutex.h>

extern struct i2c_adapter *nforce2_smbus;

static struct i2c_adapter *s4985_adapter;
static struct i2c_algorithm *s4985_algo;

/* Wrapper access functions for multiplexed SMBus */
static DEFINE_MUTEX(nforce2_lock);

static s32 nforce2_access_virt0(struct i2c_adapter *adap, u16 addr,
				unsigned short flags, char read_write,
				u8 command, int size,
				union i2c_smbus_data *data)
{ … }

/* We remember the last used channels combination so as to only switch
   channels when it is really needed. This greatly reduces the SMBus
   overhead, but also assumes that nobody will be writing to the PCA9556
   in our back. */
static u8 last_channels;

static inline s32 nforce2_access_channel(struct i2c_adapter *adap, u16 addr,
					 unsigned short flags, char read_write,
					 u8 command, int size,
					 union i2c_smbus_data *data,
					 u8 channels)
{ … }

static s32 nforce2_access_virt1(struct i2c_adapter *adap, u16 addr,
				unsigned short flags, char read_write,
				u8 command, int size,
				union i2c_smbus_data *data)
{ … }

static s32 nforce2_access_virt2(struct i2c_adapter *adap, u16 addr,
				unsigned short flags, char read_write,
				u8 command, int size,
				union i2c_smbus_data *data)
{ … }

static s32 nforce2_access_virt3(struct i2c_adapter *adap, u16 addr,
				unsigned short flags, char read_write,
				u8 command, int size,
				union i2c_smbus_data *data)
{ … }

static s32 nforce2_access_virt4(struct i2c_adapter *adap, u16 addr,
				unsigned short flags, char read_write,
				u8 command, int size,
				union i2c_smbus_data *data)
{ … }

static int __init nforce2_s4985_init(void)
{ … }

static void __exit nforce2_s4985_exit(void)
{ … }

MODULE_AUTHOR(…) …;
MODULE_DESCRIPTION(…) …;
MODULE_LICENSE(…) …;

module_init(…) …;
module_exit(nforce2_s4985_exit);