root/i2c/trunk/kernel/i2c-algo-biths.h @ 3749

/* ------------------------------------------------------------------------- */
/* i2c-algo-biths.h i2c driver algorithms for faster bit-shift adapters      */
/* ------------------------------------------------------------------------- */
/*   Copyright (C) 1995-99 Simon G. Vogl

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.                */
/* ------------------------------------------------------------------------- */

/* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and even
   Frodo Looijaard <frodol@dds.nl> */

/* $Id$ */

#ifndef I2C_ALGO_BITHS_H
#define I2C_ALGO_BITHS_H 1

#include "i2c.h"
#include <linux/sched.h>

#if 1
#define _HS_ATTR_
#else
#define _HS_ATTR_ __attribute__ ((regparm (2)))
#endif

#ifdef _HW_NO_INLINE_
#define _HW_ATTR_ __attribute__ ((regparm (2)))
#else
#define _HW_ATTR_ inline 
#endif

/* --- Defines for bit-adapters --------------------------------------- */
/*
 * This struct contains the hw-dependent functions of bit-style adapters to 
 * manipulate the line states, and to init any hw-specific features. This is
 * only used if you have more than one hw-type of adapter running. 
 */
struct i2c_algo_biths_data {
        void *hw_data;          /* private data for lowlevel routines */
        int hw_state;
        void (*setscl)(struct i2c_algo_biths_data *adap) _HS_ATTR_ ;
        void (*setsda)(struct i2c_algo_biths_data *adap) _HS_ATTR_ ;
        int (*getscl) (struct i2c_algo_biths_data *adap) _HS_ATTR_ ;
        int (*getsda) (struct i2c_algo_biths_data *adap) _HS_ATTR_ ;

        void (*setstate)(struct i2c_algo_biths_data *adap) _HS_ATTR_ ;
        void (*set_timer)(struct i2c_algo_biths_data *adap) _HS_ATTR_ ;
        void (*run_timer)(struct i2c_algo_biths_data *adap) _HS_ATTR_ ;

        short ctrl;
        short errors;
        char shiftreg;

        /* local settings */
        unsigned long bclock;
        unsigned long xloops;   /* 1/4 clock-cycle time in x86 TSC ticks */
                                /* i.e. bus clock is 250*0x10c6 / xloops kHz */

        int timeout;            /* in jiffies */
        char *name;             /* replicate i2c_adapter->name */
        char *dstr;             /* protocol debug string */
};

#define I2C_BIT_ADAP_MAX        16

#define _HS_SCL         0x0001
#define _HS_SDA         0x0002
#define _HS_SDA_FREE    0x0004  /* client has SDA control */
#define _HS_STD_MODE    0x0008  /* drop speed to 100kHz */
#define _HS_DBL_DT      0x0010  /* T_sclhi is twice longer */

#define _HS_NAK         0x0001
#define _HS_TIMEOUT     0x0002
#define _HS_SDA_ARB     0x0004
#define _HS_HW_FAIL     0x0008

int i2c_biths_add_bus(struct i2c_adapter *);
int i2c_biths_del_bus(struct i2c_adapter *);

#endif /* I2C_ALGO_BITHS_H */

#ifdef INCLUDE_BITHS_INLINES

/* --- setting states on the bus with the right timing: --------------- */

#define _hw_timer_set(adap) adap->set_timer(adap)
#define _hw_timer_run(adap) adap->run_timer(adap)

static inline int sda_not_set(struct i2c_algo_biths_data *adap, int rdcount)
{
    int sda;
    /* allow some rise/fall time */
    while ( rdcount-- ) {
        sda = _hw_getsda(adap->hw_data);
        if (adap->ctrl & _HS_SDA) {
            if (sda)
                return 0;
            if (!rdcount) {
                adap->errors |= _HS_SDA_ARB;
                return -1;
            }
        } else { /* !(adap->ctrl & _HS_SDA) */
            if (!sda)
                return 0;
            if (!rdcount) {
                adap->errors |= _HS_HW_FAIL;
                return -1;
            }
        }
    }
    return 0;
}

static inline void i2c_bit_setsda(struct i2c_algo_biths_data *adap)
{
    _hw_setsda(adap->hw_data, adap->hw_state);
    if ( !(adap->ctrl & _HS_SDA_FREE) && sda_not_set(adap, 10)) {
        return;
    }
    _hw_timer_set(adap);
    _hw_timer_run(adap);
}

/*
 * Raise scl line, and do check for delays. This is necessary for slower
 * devices.
 */

static inline void i2c_bit_setscl(struct i2c_algo_biths_data *adap)
{
#ifndef HW_CANNOT_READ_SCL /* Not all adapters have scl sense line... */
    int rdcount = 10;
    _hw_setscl(adap->hw_data, adap->hw_state);
    if (adap->ctrl & _HS_SCL) {
        unsigned long start;
        /* allow some rise time */
        while (rdcount && !_hw_getscl(adap->hw_data)) rdcount--;
        /* else clock synchronisation, give more time */
        start = jiffies;
        while (!rdcount && !_hw_getscl(adap->hw_data)) {
            if ( time_after(jiffies, start+adap->timeout) ) {
                adap->errors |= _HS_TIMEOUT; /* scl undef */
                return;
            }
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,5,0)
            if (current->need_resched)
                schedule();
#else
            cond_resched();
#endif
        }
        _hw_timer_set(adap);
        /* test for SDA arbitration when SCL is high */
        if ( !(adap->ctrl & _HS_SDA_FREE) && sda_not_set(adap, 1)) {
            return;
        }
    } else {
        /* allow some fall time */
        while (rdcount && _hw_getscl(adap->hw_data)) rdcount--;
        if ( !rdcount ) {
            adap->errors |= _HS_HW_FAIL;
            return;
        }
        _hw_timer_set(adap);
    }
#else
    _hw_setscl(adap->hw_data, adap->hw_state);
    _hw_timer_set(adap);
#endif /* HW_CANNOT_READ_SCL */
    _hw_timer_run(adap);
}

static inline int i2c_bit_getscl(struct i2c_algo_biths_data *adap)
{
    return _hw_getscl(adap->hw_data);
}

static inline int i2c_bit_getsda(struct i2c_algo_biths_data *adap)
{
    return _hw_getsda(adap->hw_data);
}

#endif