04451b4369
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@21445 a1c6a512-1295-4272-9138-f99709370657
194 lines
3.3 KiB
C
194 lines
3.3 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2008 by Rob Purchase
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#include "config.h"
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#include "system.h"
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#include "i2c.h"
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#include "i2c-target.h"
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/* Delay loop based on CPU frequency (FREQ>>22 is 7..45 for 32MHz..192MHz) */
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static inline void delay_loop(void)
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{
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unsigned long x;
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for (x = (unsigned)(FREQ>>22); x; x--);
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}
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#define DELAY delay_loop()
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static struct mutex i2c_mtx;
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void i2c_init(void)
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{
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mutex_init(&i2c_mtx);
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}
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void i2c_start(void)
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{
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SDA_OUTPUT;
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SCL_HI;
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SDA_HI;
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DELAY;
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SDA_LO;
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DELAY;
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SCL_LO;
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DELAY;
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}
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void i2c_stop(void)
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{
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SDA_OUTPUT;
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SDA_LO;
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DELAY;
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SCL_HI;
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DELAY;
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SDA_HI;
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DELAY;
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}
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void i2c_outb(unsigned char byte)
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{
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int bit;
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SDA_OUTPUT;
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for (bit = 0; bit < 8; bit++)
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{
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if ((byte<<bit) & 0x80)
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SDA_HI;
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else
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SDA_LO;
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DELAY;
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SCL_HI;
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DELAY;
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SCL_LO;
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DELAY;
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}
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}
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unsigned char i2c_inb(int ack)
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{
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int i;
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unsigned char byte = 0;
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SDA_INPUT;
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/* clock in each bit, MSB first */
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for ( i=0x80; i; i>>=1 )
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{
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SCL_HI;
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DELAY;
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if ( SDA ) byte |= i;
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SCL_LO;
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DELAY;
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}
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i2c_ack(ack);
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return byte;
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}
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void i2c_ack(int bit)
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{
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SDA_OUTPUT;
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if (bit)
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SDA_HI;
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else
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SDA_LO;
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SCL_HI;
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DELAY;
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SCL_LO;
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DELAY;
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}
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int i2c_getack(void)
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{
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bool ack_bit;
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SDA_INPUT;
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SCL_HI;
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DELAY;
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ack_bit = SDA;
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DELAY;
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SCL_LO;
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DELAY;
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return ack_bit;
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}
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/* device = 8 bit slave address */
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int i2c_write(int device, const unsigned char* buf, int count )
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{
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int i = 0;
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mutex_lock(&i2c_mtx);
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i2c_start();
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i2c_outb(device & 0xfe);
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while (!i2c_getack() && i < count)
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{
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i2c_outb(buf[i++]);
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}
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i2c_stop();
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mutex_unlock(&i2c_mtx);
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return 0;
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}
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/* device = 8 bit slave address */
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int i2c_readmem(int device, int address, unsigned char* buf, int count )
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{
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int i = 0;
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mutex_lock(&i2c_mtx);
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i2c_start();
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i2c_outb(device & 0xfe);
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if (i2c_getack()) goto exit;
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i2c_outb(address);
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if (i2c_getack()) goto exit;
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i2c_start();
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i2c_outb(device | 1);
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if (i2c_getack()) goto exit;
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while (i < count)
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{
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buf[i] = i2c_inb(i == (count-1));
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i++;
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}
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exit:
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i2c_stop();
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mutex_unlock(&i2c_mtx);
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return 0;
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}
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