Generic bitbang I2C driver
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@8782 a1c6a512-1295-4272-9138-f99709370657
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Linus Nielsen Feltzing
parent
37b15d3833
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2 changed files with 257 additions and 0 deletions
204
firmware/drivers/generic_i2c.c
Executable file
204
firmware/drivers/generic_i2c.c
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/***************************************************************************
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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) 2006 by Linus Nielsen Feltzing
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*
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* All files in this archive are subject to the GNU General Public License.
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* See the file COPYING in the source tree root for full license agreement.
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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 "cpu.h"
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#include <stdbool.h>
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#include <stdlib.h>
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#include "debug.h"
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#include "logf.h"
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#include "generic_i2c.h"
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int i2c_num_ifs = 0;
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struct i2c_interface *i2c_if[5];
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static void i2c_start(struct i2c_interface *iface)
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{
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iface->sda_hi();
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iface->scl_hi();
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iface->sda_lo();
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iface->delay_hd_sta();
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iface->scl_lo();
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}
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static void i2c_stop(struct i2c_interface *iface)
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{
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iface->sda_lo();
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iface->scl_hi();
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iface->delay_su_sto();
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iface->sda_hi();
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}
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static void i2c_ack(struct i2c_interface *iface, bool ack)
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{
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iface->scl_lo();
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if ( ack )
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iface->sda_lo();
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else
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iface->sda_hi();
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iface->delay_su_dat();
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iface->scl_hi();
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iface->delay_thigh();
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iface->scl_lo();
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}
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static int i2c_getack(struct i2c_interface *iface)
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{
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int ret = 1;
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iface->sda_input();
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iface->delay_su_dat();
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iface->scl_hi();
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if (iface->sda())
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ret = 0; /* ack failed */
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iface->delay_thigh();
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iface->scl_lo();
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iface->sda_hi();
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iface->sda_output();
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iface->delay_hd_dat();
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return ret;
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}
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static unsigned char i2c_inb(struct i2c_interface *iface, bool ack)
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{
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int i;
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unsigned char byte = 0;
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/* clock in each bit, MSB first */
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for ( i=0x80; i; i>>=1 ) {
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iface->sda_input();
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iface->scl_hi();
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iface->delay_thigh();
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if (iface->sda())
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byte |= i;
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iface->scl_lo();
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iface->delay_hd_dat();
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iface->sda_output();
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}
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i2c_ack(iface, ack);
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return byte;
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}
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static void i2c_outb(struct i2c_interface *iface, unsigned char byte)
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{
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int i;
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/* clock out each bit, MSB first */
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for (i=0x80; i; i>>=1) {
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if (i & byte)
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iface->sda_hi();
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else
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iface->sda_lo();
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iface->delay_su_dat();
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iface->scl_hi();
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iface->delay_thigh();
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iface->scl_lo();
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iface->delay_hd_dat();
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}
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iface->sda_hi();
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}
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static struct i2c_interface *find_if(int address)
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{
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int i;
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for(i = 0;i < i2c_num_ifs;i++) {
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if(i2c_if[i]->address == address)
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return i2c_if[i];
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}
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return NULL;
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}
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int i2c_write_data(int bus_address, int address,
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const unsigned char* buf, int count)
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{
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int i;
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int ret = 0;
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struct i2c_interface *iface = find_if(bus_address);
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if(!iface)
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return -1;
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i2c_start(iface);
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i2c_outb(iface, iface->address & 0xfe);
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if (i2c_getack(iface)) {
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i2c_outb(iface, address);
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if (i2c_getack(iface)) {
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for(i = 0;i < count;i++) {
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i2c_outb(iface, buf[i]);
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if (!i2c_getack(iface)) {
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ret = -3;
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break;
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}
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}
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} else {
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ret = -2;
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}
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} else {
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logf("i2c_write_data() - no ack\n");
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ret = -1;
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}
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i2c_stop(iface);
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return ret;
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}
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int i2c_read_data(int bus_address, int address,
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unsigned char* buf, int count)
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{
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int i;
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int ret = 0;
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struct i2c_interface *iface = find_if(bus_address);
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if(!iface)
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return -1;
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i2c_start(iface);
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i2c_outb(iface, iface->address & 0xfe);
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if (i2c_getack(iface)) {
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i2c_outb(iface, address);
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if (i2c_getack(iface)) {
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i2c_start(iface);
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i2c_outb(iface, iface->address | 1);
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if (i2c_getack(iface)) {
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for(i = 0;i < count-1;i++)
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buf[i] = i2c_inb(iface, true);
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buf[i] = i2c_inb(iface, false);
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} else {
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ret = -3;
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}
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} else {
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ret = -2;
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}
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} else {
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ret = -1;
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}
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i2c_stop(iface);
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return ret;
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}
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void i2c_add_node(struct i2c_interface *iface)
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{
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i2c_if[i2c_num_ifs++] = iface;
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}
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53
firmware/export/generic_i2c.h
Executable file
53
firmware/export/generic_i2c.h
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@ -0,0 +1,53 @@
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/***************************************************************************
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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) 2006 by Linus Nielsen Feltzing
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*
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* All files in this archive are subject to the GNU General Public License.
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* See the file COPYING in the source tree root for full license agreement.
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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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#ifndef _GEN_I2C_
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#define _GEN_I2C_
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struct i2c_interface
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{
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unsigned char address; /* Address of the chip that this interface
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describes */
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void (*scl_hi)(void); /* Drive SCL high, might sleep on clk stretch */
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void (*scl_lo)(void); /* Drive SCL low */
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void (*sda_hi)(void); /* Drive SDA high */
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void (*sda_lo)(void); /* Drive SDA low */
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void (*sda_input)(void); /* Set SDA as input */
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void (*sda_output)(void); /* Set SDA as output */
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void (*scl_input)(void); /* Set SCL as input */
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void (*scl_output)(void); /* Set SCL as output */
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int (*scl)(void); /* Read SCL, returns 0 or non-zero */
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int (*sda)(void); /* Read SDA, returns 0 or non-zero */
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/* These are the delays specified in the I2C specification, the
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time pairs to the right are the minimum 100kHz and 400kHz specs */
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void (*delay_hd_sta)(void); /* START SDA hold (tHD:SDA) 4.0us/0.6us */
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void (*delay_hd_dat)(void); /* SDA hold (tHD:DAT) 5.0us/0us */
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void (*delay_su_dat)(void); /* SDA setup (tSU:DAT) 250ns/100ns */
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void (*delay_su_sto)(void); /* STOP setup (tSU:STO) 4.0us/0.6us */
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void (*delay_su_sta)(void); /* Rep. START setup (tSU:STA) 4.7us/0.6us */
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void (*delay_thigh)(void); /* SCL high period (tHIGH) 4.0us/0.6us */
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};
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extern void i2c_add_node(struct i2c_interface *iface);
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extern int i2c_write_data(int bus_address, int address,
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const unsigned char* buf, int count);
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extern int i2c_read_data(int bus_address, int address,
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unsigned char* buf, int count);
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#endif
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