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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2008 by Rob Purchase
*
* 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 software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include "config.h"
#include "system.h"
#include "i2c.h"
#include "i2c-target.h"
/* Delay loop based on CPU frequency (FREQ>>22 is 7..45 for 32MHz..192MHz) */
static inline void delay_loop(void)
{
asm volatile (" mov %[freq], %[freq], asr#22 \n\t"
"1: subs %[freq], %[freq], #1 \n\t"
" bne 1b"
: : [freq] "r" (cpu_frequency) : "memory");
}
#define DELAY delay_loop()
static struct mutex i2c_mtx;
void i2c_init(void)
{
mutex_init(&i2c_mtx);
}
void i2c_start(void)
{
SDA_OUTPUT;
SCL_HI;
SDA_HI;
DELAY;
SDA_LO;
DELAY;
SCL_LO;
DELAY;
}
void i2c_stop(void)
{
SDA_OUTPUT;
SDA_LO;
DELAY;
SCL_HI;
DELAY;
SDA_HI;
DELAY;
}
void i2c_outb(unsigned char byte)
{
int bit;
SDA_OUTPUT;
for (bit = 0; bit < 8; bit++)
{
if ((byte<<bit) & 0x80)
SDA_HI;
else
SDA_LO;
DELAY;
SCL_HI;
DELAY;
SCL_LO;
DELAY;
}
}
unsigned char i2c_inb(int ack)
{
int i;
unsigned char byte = 0;
SDA_INPUT;
/* clock in each bit, MSB first */
for ( i=0x80; i; i>>=1 )
{
SCL_HI;
DELAY;
if ( SDA ) byte |= i;
SCL_LO;
DELAY;
}
i2c_ack(ack);
return byte;
}
void i2c_ack(int bit)
{
SDA_OUTPUT;
if (bit)
SDA_HI;
else
SDA_LO;
SCL_HI;
DELAY;
SCL_LO;
DELAY;
}
int i2c_getack(void)
{
bool ack_bit;
SDA_INPUT;
SCL_HI;
DELAY;
ack_bit = SDA;
DELAY;
SCL_LO;
DELAY;
return ack_bit;
}
/* device = 8 bit slave address */
int i2c_write(int device, const unsigned char* buf, int count )
{
int i = 0;
mutex_lock(&i2c_mtx);
i2c_start();
i2c_outb(device & 0xfe);
while (!i2c_getack() && i < count)
{
i2c_outb(buf[i++]);
}
i2c_stop();
mutex_unlock(&i2c_mtx);
return 0;
}
/* device = 8 bit slave address */
int i2c_readmem(int device, int address, unsigned char* buf, int count )
{
int i = 0;
mutex_lock(&i2c_mtx);
i2c_start();
i2c_outb(device & 0xfe);
if (i2c_getack()) goto exit;
i2c_outb(address);
if (i2c_getack()) goto exit;
i2c_start();
i2c_outb(device | 1);
if (i2c_getack()) goto exit;
while (i < count)
{
buf[i] = i2c_inb(i == (count-1));
i++;
}
exit:
i2c_stop();
mutex_unlock(&i2c_mtx);
return 0;
}
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