321 lines
7.2 KiB
C
321 lines
7.2 KiB
C
/*-
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* Copyright (c) 1998 Nicolas Souchu
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*
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*/
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/*
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* Generic I2C bit-banging code
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*
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* Example:
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*
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* iicbus
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* / \
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* iicbb pcf
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* | \
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* bti2c lpbb
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*
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* From Linux I2C generic interface
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* (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
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*
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* TODO: port Peter's generic bit-banging code <dufault@hda.com>
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*/
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/systm.h>
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#include <sys/module.h>
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#include <sys/bus.h>
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#include <sys/uio.h>
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#include <machine/clock.h>
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#include <dev/iicbus/iiconf.h>
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#include <dev/iicbus/iicbus.h>
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#include <dev/smbus/smbconf.h>
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#include "iicbus_if.h"
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#include "iicbb_if.h"
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struct iicbb_softc {
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int dummy;
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};
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static int iicbb_probe(device_t);
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static int iicbb_attach(device_t);
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static int iicbb_print_child(device_t, device_t);
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static int iicbb_callback(device_t, int, caddr_t);
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static int iicbb_start(device_t, u_char, int);
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static int iicbb_stop(device_t);
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static int iicbb_write(device_t, char *, int, int *, int);
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static int iicbb_read(device_t, char *, int, int *, int, int);
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static int iicbb_reset(device_t, u_char, u_char, u_char *);
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static device_method_t iicbb_methods[] = {
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/* device interface */
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DEVMETHOD(device_probe, iicbb_probe),
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DEVMETHOD(device_attach, iicbb_attach),
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/* bus interface */
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DEVMETHOD(bus_print_child, iicbb_print_child),
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/* iicbus interface */
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DEVMETHOD(iicbus_callback, iicbb_callback),
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DEVMETHOD(iicbus_start, iicbb_start),
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DEVMETHOD(iicbus_repeated_start, iicbb_start),
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DEVMETHOD(iicbus_stop, iicbb_stop),
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DEVMETHOD(iicbus_write, iicbb_write),
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DEVMETHOD(iicbus_read, iicbb_read),
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DEVMETHOD(iicbus_reset, iicbb_reset),
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{ 0, 0 }
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};
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static driver_t iicbb_driver = {
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"iicbb",
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iicbb_methods,
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sizeof(struct iicbb_softc),
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};
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static devclass_t iicbb_devclass;
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static int iicbb_probe(device_t dev)
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{
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device_set_desc(dev, "I2C generic bit-banging driver");
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return (0);
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}
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static int iicbb_attach(device_t dev)
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{
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return (0);
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}
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static int
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iicbb_print_child(device_t bus, device_t dev)
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{
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int error;
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int retval = 0;
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u_char oldaddr;
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retval += bus_print_child_header(bus, dev);
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/* retrieve the interface I2C address */
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error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
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if (error == IIC_ENOADDR) {
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retval += printf(" on %s master-only\n",
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device_get_nameunit(bus));
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} else {
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/* restore the address */
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IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
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retval += printf(" on %s addr 0x%x\n",
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device_get_nameunit(bus), oldaddr & 0xff);
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}
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return (retval);
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}
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#define I2C_SET(dev,ctrl,data) \
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IICBB_SETLINES(device_get_parent(dev), ctrl, data)
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#define I2C_GET(dev) (IICBB_GETDATALINE(device_get_parent(dev)))
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static int i2c_debug = 0;
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#define I2C_DEBUG(x) if (i2c_debug) (x)
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static void iicbb_one(device_t dev)
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{
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I2C_SET(dev,0,1);
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I2C_SET(dev,1,1);
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I2C_SET(dev,0,1);
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return;
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}
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static void iicbb_zero(device_t dev)
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{
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I2C_SET(dev,0,0);
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I2C_SET(dev,1,0);
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I2C_SET(dev,0,0);
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return;
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}
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/*
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* Waiting for ACKNOWLEDGE.
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*
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* When a chip is being addressed or has received data it will issue an
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* ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
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* (set it to high level) and then release the CLOCK line.
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* Now it must wait for the SLAVE to pull the DATA line low.
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* Actually on the bus this looks like a START condition so nothing happens
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* because of the fact that the IC's that have not been addressed are doing
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* nothing.
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*
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* When the SLAVE has pulled this line low the MASTER will take the CLOCK
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* line low and then the SLAVE will release the SDA (data) line.
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*/
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static int iicbb_ack(device_t dev, int timeout)
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{
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int noack;
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int k = timeout/10;
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I2C_SET(dev,0,1);
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I2C_SET(dev,1,1);
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do {
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noack = I2C_GET(dev);
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if (!noack)
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break;
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DELAY(10); /* XXX wait 10us */
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} while (k--);
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I2C_SET(dev,0,1);
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I2C_DEBUG(printf("%c ",noack?'-':'+'));
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return (noack);
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}
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static void iicbb_sendbyte(device_t dev, u_char data)
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{
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int i;
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I2C_SET(dev,0,0);
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for (i=7; i>=0; i--)
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(data&(1<<i)) ? iicbb_one(dev) : iicbb_zero(dev);
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I2C_DEBUG(printf("w%02x",(int)data));
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return;
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}
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static u_char iicbb_readbyte(device_t dev, int last)
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{
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int i;
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unsigned char data=0;
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I2C_SET(dev,0,1);
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for (i=7; i>=0; i--)
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{
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I2C_SET(dev,1,1);
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if (I2C_GET(dev))
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data |= (1<<i);
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I2C_SET(dev,0,1);
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}
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last ? iicbb_one(dev) : iicbb_zero(dev);
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I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
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return data;
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}
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static int iicbb_callback(device_t dev, int index, caddr_t data)
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{
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return (IICBB_CALLBACK(device_get_parent(dev), index, data));
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}
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static int iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
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{
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return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
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}
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static int iicbb_start(device_t dev, u_char slave, int timeout)
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{
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int error;
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I2C_DEBUG(printf("<"));
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I2C_SET(dev,0,1);
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I2C_SET(dev,1,1);
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I2C_SET(dev,1,0);
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I2C_SET(dev,0,0);
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/* send address */
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iicbb_sendbyte(dev, slave);
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/* check for ack */
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if (iicbb_ack(dev, timeout)) {
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error = IIC_ENOACK;
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goto error;
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}
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return(0);
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error:
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iicbb_stop(dev);
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return (error);
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}
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static int iicbb_stop(device_t dev)
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{
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I2C_SET(dev,0,0);
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I2C_SET(dev,1,0);
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I2C_SET(dev,1,1);
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I2C_DEBUG(printf(">"));
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return (0);
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}
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static int iicbb_write(device_t dev, char * buf, int len, int *sent,
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int timeout)
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{
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int bytes, error = 0;
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bytes = 0;
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while (len) {
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/* send byte */
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iicbb_sendbyte(dev,(u_char)*buf++);
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/* check for ack */
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if (iicbb_ack(dev, timeout)) {
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error = IIC_ENOACK;
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goto error;
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}
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bytes ++;
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len --;
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}
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error:
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*sent = bytes;
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return (error);
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}
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static int iicbb_read(device_t dev, char * buf, int len, int *read,
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int last, int delay)
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{
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int bytes;
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bytes = 0;
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while (len) {
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/* XXX should insert delay here */
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*buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0);
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bytes ++;
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len --;
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}
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*read = bytes;
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return (0);
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}
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DRIVER_MODULE(iicbb, bti2c, iicbb_driver, iicbb_devclass, 0, 0);
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DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0);
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