/* * i2c-algo-sgi.c: i2c driver algorithms for SGI adapters. *  * This file is subject to the terms and conditions of the GNU General Public * License version 2 as published by the Free Software Foundation. * * Copyright (C) 2003 Ladislav Michl <ladis@linux-mips.org> */#include <linux/kernel.h>#include <linux/module.h>#include <linux/init.h>#include <linux/errno.h>#include <linux/delay.h>#include <linux/i2c.h>#include <linux/i2c-algo-sgi.h>#define SGI_I2C_FORCE_IDLE	(0 << 0)#define SGI_I2C_NOT_IDLE	(1 << 0)#define SGI_I2C_WRITE		(0 << 1)#define SGI_I2C_READ		(1 << 1)#define SGI_I2C_RELEASE_BUS	(0 << 2)#define SGI_I2C_HOLD_BUS	(1 << 2)#define SGI_I2C_XFER_DONE	(0 << 4)#define SGI_I2C_XFER_BUSY	(1 << 4)#define SGI_I2C_ACK		(0 << 5)#define SGI_I2C_NACK		(1 << 5)#define SGI_I2C_BUS_OK		(0 << 7)#define SGI_I2C_BUS_ERR		(1 << 7)#define get_control()		adap->getctrl(adap->data)#define set_control(val)	adap->setctrl(adap->data, val)#define read_data()		adap->rdata(adap->data)#define write_data(val)		adap->wdata(adap->data, val)static int wait_xfer_done(struct i2c_algo_sgi_data *adap){	int i;	for (i = 0; i < adap->xfer_timeout; i++) {		if ((get_control() & SGI_I2C_XFER_BUSY) == 0)			return 0;		udelay(1);	}	return -ETIMEDOUT;}static int wait_ack(struct i2c_algo_sgi_data *adap){	int i;	if (wait_xfer_done(adap))		return -ETIMEDOUT;	for (i = 0; i < adap->ack_timeout; i++) {		if ((get_control() & SGI_I2C_NACK) == 0)			return 0;		udelay(1);	}	return -ETIMEDOUT;}static int force_idle(struct i2c_algo_sgi_data *adap){	int i;	set_control(SGI_I2C_FORCE_IDLE);	for (i = 0; i < adap->xfer_timeout; i++) {		if ((get_control() & SGI_I2C_NOT_IDLE) == 0)			goto out;		udelay(1);	}	return -ETIMEDOUT;out:	if (get_control() & SGI_I2C_BUS_ERR)		return -EIO;	return 0;}static int do_address(struct i2c_algo_sgi_data *adap, unsigned int addr,		      int rd){	if (rd)		set_control(SGI_I2C_NOT_IDLE);	/* Check if bus is idle, eventually force it to do so */	if (get_control() & SGI_I2C_NOT_IDLE)		if (force_idle(adap))	                return -EIO;	/* Write out the i2c chip address and specify operation */	set_control(SGI_I2C_HOLD_BUS | SGI_I2C_WRITE | SGI_I2C_NOT_IDLE);	if (rd)		addr |= 1;	write_data(addr);	if (wait_ack(adap))		return -EIO;	return 0;}static int i2c_read(struct i2c_algo_sgi_data *adap, unsigned char *buf,		    unsigned int len){	int i;	set_control(SGI_I2C_HOLD_BUS | SGI_I2C_READ | SGI_I2C_NOT_IDLE);	for (i = 0; i < len; i++) {		if (wait_xfer_done(adap))			return -EIO;		buf[i] = read_data();	}	set_control(SGI_I2C_RELEASE_BUS | SGI_I2C_FORCE_IDLE);	return 0;}static int i2c_write(struct i2c_algo_sgi_data *adap, unsigned char *buf,		     unsigned int len){	int i;	/* We are already in write state */	for (i = 0; i < len; i++) {		write_data(buf[i]);		if (wait_ack(adap))			return -EIO;	}	return 0;}static int sgi_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs,		    int num){	struct i2c_algo_sgi_data *adap = i2c_adap->algo_data;	struct i2c_msg *p;	int i, err = 0;	for (i = 0; !err && i < num; i++) {		p = &msgs[i];		err = do_address(adap, p->addr, p->flags & I2C_M_RD);		if (err || !p->len)			continue;		if (p->flags & I2C_M_RD)			err = i2c_read(adap, p->buf, p->len);		else			err = i2c_write(adap, p->buf, p->len);	}	return (err < 0) ? err : i;}static u32 sgi_func(struct i2c_adapter *adap){	return I2C_FUNC_SMBUS_EMUL;}static const struct i2c_algorithm sgi_algo = {	.master_xfer	= sgi_xfer,	.functionality	= sgi_func,};/*  * registering functions to load algorithms at runtime  */int i2c_sgi_add_bus(struct i2c_adapter *adap){	adap->algo = &sgi_algo;	return i2c_add_adapter(adap);}int i2c_sgi_del_bus(struct i2c_adapter *adap){	return i2c_del_adapter(adap);}EXPORT_SYMBOL(i2c_sgi_add_bus);EXPORT_SYMBOL(i2c_sgi_del_bus);MODULE_AUTHOR("Ladislav Michl <ladis@linux-mips.org>");MODULE_DESCRIPTION("I2C-Bus SGI algorithm");MODULE_LICENSE("GPL");