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iicbb.c
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/*-
* Copyright (c) 1998, 2001 Nicolas Souchu
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*
*/
/*
* Generic I2C bit-banging code
*
* Example:
*
* iicbus
* / \
* iicbb pcf
* | \
* bti2c lpbb
*
* From Linux I2C generic interface
* (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
*
*/
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/module.h>
#include <sys/bus.h>
#include <sys/uio.h>
#include <dev/iicbus/iiconf.h>
#include <dev/iicbus/iicbus.h>
#include <dev/smbus/smbconf.h>
#include "iicbus_if.h"
#include "iicbb_if.h"
struct iicbb_softc {
device_t iicbus;
};
static int iicbb_probe(device_t);
static int iicbb_attach(device_t);
static int iicbb_detach(device_t);
static int iicbb_print_child(device_t, device_t);
static int iicbb_callback(device_t, int, caddr_t);
static int iicbb_start(device_t, u_char, int);
static int iicbb_stop(device_t);
static int iicbb_write(device_t, char *, int, int *, int);
static int iicbb_read(device_t, char *, int, int *, int, int);
static int iicbb_reset(device_t, u_char, u_char, u_char *);
static device_method_t iicbb_methods[] = {
/* device interface */
DEVMETHOD(device_probe, iicbb_probe),
DEVMETHOD(device_attach, iicbb_attach),
DEVMETHOD(device_detach, iicbb_detach),
/* bus interface */
DEVMETHOD(bus_print_child, iicbb_print_child),
/* iicbus interface */
DEVMETHOD(iicbus_callback, iicbb_callback),
DEVMETHOD(iicbus_start, iicbb_start),
DEVMETHOD(iicbus_repeated_start, iicbb_start),
DEVMETHOD(iicbus_stop, iicbb_stop),
DEVMETHOD(iicbus_write, iicbb_write),
DEVMETHOD(iicbus_read, iicbb_read),
DEVMETHOD(iicbus_reset, iicbb_reset),
{ 0, 0 }
};
static driver_t iicbb_driver = {
"iicbb",
iicbb_methods,
sizeof(struct iicbb_softc),
};
static devclass_t iicbb_devclass;
static int iicbb_probe(device_t dev)
{
device_set_desc(dev, "I2C bit-banging driver");
return (0);
}
static int iicbb_attach(device_t dev)
{
struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
bzero(sc, sizeof(struct iicbb_softc));
sc->iicbus = device_add_child(dev, "iicbus", -1);
if (!sc->iicbus)
return (ENXIO);
bus_generic_attach(dev);
return (0);
}
static int iicbb_detach(device_t dev)
{
struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
if (sc->iicbus) {
bus_generic_detach(dev);
device_delete_child(dev, sc->iicbus);
}
return (0);
}
static int
iicbb_print_child(device_t bus, device_t dev)
{
int error;
int retval = 0;
u_char oldaddr;
retval += bus_print_child_header(bus, dev);
/* retrieve the interface I2C address */
error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
if (error == IIC_ENOADDR) {
retval += printf(" on %s master-only\n",
device_get_nameunit(bus));
} else {
/* restore the address */
IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
retval += printf(" on %s addr 0x%x\n",
device_get_nameunit(bus), oldaddr & 0xff);
}
return (retval);
}
#define IIC_DELAY 10
#define I2C_SETSDA(dev,val) do { \
IICBB_SETSDA(device_get_parent(dev), val); \
DELAY(IIC_DELAY); \
} while (0)
#define I2C_SETSCL(dev,val) do { \
iicbb_setscl(dev, val, 100); \
} while (0)
#define I2C_SET(dev,ctrl,data) do { \
I2C_SETSCL(dev, ctrl); \
I2C_SETSDA(dev, data); \
} while (0)
#define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev)))
#define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev)))
static int i2c_debug = 0;
#define I2C_DEBUG(x) do { \
if (i2c_debug) (x); \
} while (0)
#define I2C_LOG(format,args...) do { \
printf(format, args); \
} while (0)
static void iicbb_setscl(device_t dev, int val, int timeout)
{
int k = 0;
IICBB_SETSCL(device_get_parent(dev), val);
DELAY(IIC_DELAY);
while (val && !I2C_GETSCL(dev) && k++ < timeout) {
IICBB_SETSCL(device_get_parent(dev), val);
DELAY(IIC_DELAY);
}
return;
}
static void iicbb_one(device_t dev, int timeout)
{
I2C_SET(dev,0,1);
I2C_SET(dev,1,1);
I2C_SET(dev,0,1);
return;
}
static void iicbb_zero(device_t dev, int timeout)
{
I2C_SET(dev,0,0);
I2C_SET(dev,1,0);
I2C_SET(dev,0,0);
return;
}
/*
* Waiting for ACKNOWLEDGE.
*
* When a chip is being addressed or has received data it will issue an
* ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
* (set it to high level) and then release the CLOCK line.
* Now it must wait for the SLAVE to pull the DATA line low.
* Actually on the bus this looks like a START condition so nothing happens
* because of the fact that the IC's that have not been addressed are doing
* nothing.
*
* When the SLAVE has pulled this line low the MASTER will take the CLOCK
* line low and then the SLAVE will release the SDA (data) line.
*/
static int iicbb_ack(device_t dev, int timeout)
{
int noack;
int k = 0;
I2C_SET(dev,0,1);
I2C_SET(dev,1,1);
do {
noack = I2C_GETSDA(dev);
if (!noack)
break;
DELAY(10);
k += 10;
} while (k < timeout);
I2C_SET(dev,0,1);
I2C_DEBUG(printf("%c ",noack?'-':'+'));
return (noack);
}
static void iicbb_sendbyte(device_t dev, u_char data, int timeout)
{
int i;
for (i=7; i>=0; i--) {
if (data&(1<<i)) {
iicbb_one(dev, timeout);
} else {
iicbb_zero(dev, timeout);
}
}
I2C_DEBUG(printf("w%02x",(int)data));
return;
}
static u_char iicbb_readbyte(device_t dev, int last, int timeout)
{
int i;
unsigned char data=0;
I2C_SET(dev,0,1);
for (i=7; i>=0; i--)
{
I2C_SET(dev,1,1);
if (I2C_GETSDA(dev))
data |= (1<<i);
I2C_SET(dev,0,1);
}
if (last) {
iicbb_one(dev, timeout);
} else {
iicbb_zero(dev, timeout);
}
I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
return data;
}
static int iicbb_callback(device_t dev, int index, caddr_t data)
{
return (IICBB_CALLBACK(device_get_parent(dev), index, data));
}
static int iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
{
return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
}
static int iicbb_start(device_t dev, u_char slave, int timeout)
{
int error;
I2C_DEBUG(printf("<"));
I2C_SET(dev,1,1);
I2C_SET(dev,1,0);
I2C_SET(dev,0,0);
/* send address */
iicbb_sendbyte(dev, slave, timeout);
/* check for ack */
if (iicbb_ack(dev, timeout)) {
error = IIC_ENOACK;
goto error;
}
return(0);
error:
iicbb_stop(dev);
return (error);
}
static int iicbb_stop(device_t dev)
{
I2C_SET(dev,0,0);
I2C_SET(dev,1,0);
I2C_SET(dev,1,1);
I2C_DEBUG(printf(">"));
return (0);
}
static int iicbb_write(device_t dev, char * buf, int len, int *sent,
int timeout)
{
int bytes, error = 0;
bytes = 0;
while (len) {
/* send byte */
iicbb_sendbyte(dev,(u_char)*buf++, timeout);
/* check for ack */
if (iicbb_ack(dev, timeout)) {
error = IIC_ENOACK;
goto error;
}
bytes ++;
len --;
}
error:
*sent = bytes;
return (error);
}
static int iicbb_read(device_t dev, char * buf, int len, int *read,
int last, int delay)
{
int bytes;
bytes = 0;
while (len) {
/* XXX should insert delay here */
*buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
bytes ++;
len --;
}
*read = bytes;
return (0);
}
DRIVER_MODULE(iicbb, bktr, iicbb_driver, iicbb_devclass, 0, 0);
DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0);
DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, 0, 0);
MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
MODULE_VERSION(iicbb, IICBB_MODVER);

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