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// Copyright 2009 Segher Boessenkool <segher@kernel.crashing.org>
// Licensed under the terms of the GNU GPL, version 2
// http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt
#include "types.h"
#include <stdlib.h>
#include "i2c.h"
static void i2c_bus_find_device(struct i2c_bus *bus, u8 address)
{
struct i2c_device *dev;
for (dev = bus->devices; dev; dev = dev->next)
if (dev->address(dev, address) == 0)
break;
bus->device = dev;
}
static int i2c_bus_write(struct i2c_bus *bus, u8 data)
{
struct i2c_device *dev = bus->device;
return dev->write(dev, data);
}
static u8 i2c_bus_read(struct i2c_bus *bus)
{
struct i2c_device *dev = bus->device;
return dev->read(dev);
}
static void i2c_bus_read_ack(struct i2c_bus *bus, int ack)
{
struct i2c_device *dev = bus->device;
if (dev->read_ack)
dev->read_ack(dev, ack);
}
struct i2c_bitbang_bus {
struct i2c_bus bus;
void (*clock)(struct i2c_bitbang_bus *);
int sda, scl, sda_dev;
int dir;
u8 bits;
int nbits;
};
struct i2c_bus *i2c_bitbang_bus_create(void)
{
return calloc(sizeof(struct i2c_bitbang_bus), 1);
}
static void clock_write(struct i2c_bitbang_bus *bb);
static void clock_write_ack(struct i2c_bitbang_bus *bb)
{
if (bb->sda_dev == 0) {
bb->clock = clock_write;
bb->bits = 0;
bb->nbits = 0;
bb->sda_dev = 1;
} else {
bb->clock = 0;
}
}
static void clock_write(struct i2c_bitbang_bus *bb)
{
bb->bits = 2*bb->bits + bb->sda;
bb->nbits++;
if (bb->nbits == 8) {
bb->sda_dev = i2c_bus_write(&bb->bus, bb->bits);
bb->clock = clock_write_ack;
}
}
static void clock_read(struct i2c_bitbang_bus *bb);
static void clock_read_ack(struct i2c_bitbang_bus *bb)
{
i2c_bus_read_ack(&bb->bus, bb->sda);
bb->clock = clock_read;
if (bb->sda == 0) {
bb->bits = i2c_bus_read(&bb->bus);
bb->nbits = 0;
bb->sda_dev = bb->bits >> 7;
bb->clock = clock_read;
} else
bb->clock = 0;
}
static void clock_read(struct i2c_bitbang_bus *bb)
{
bb->bits = 2*bb->bits;
bb->sda_dev = bb->bits >> 7;
bb->nbits++;
if (bb->nbits == 8) {
bb->sda_dev = 1;
bb->clock = clock_read_ack;
}
}
static void clock_address_ack(struct i2c_bitbang_bus *bb)
{
if (bb->dir == 0) {
bb->clock = clock_write;
bb->bits = 0;
bb->nbits = 0;
bb->sda_dev = 1;
} else {
bb->clock = clock_read;
bb->bits = i2c_bus_read(&bb->bus);
bb->nbits = 0;
bb->sda_dev = bb->bits >> 7;
}
}
static void clock_address(struct i2c_bitbang_bus *bb)
{
bb->bits = 2*bb->bits + bb->sda;
bb->nbits++;
if (bb->nbits == 8) {
i2c_bus_find_device(&bb->bus, bb->bits);
if (bb->bus.device == 0) {
bb->clock = 0;
return;
}
bb->sda_dev = 0;
bb->dir = bb->bits & 1;
bb->clock = clock_address_ack;
}
}
int i2c_bitbang(struct i2c_bus *bus, int sda, int scl)
{
struct i2c_bitbang_bus *bb = subtype(struct i2c_bitbang_bus, bus, bus);
int old_sda = bb->sda;
int old_scl = bb->scl;
bb->sda = sda;
bb->scl = scl;
if (old_scl == 1 && scl == 1) {
if (old_sda == 1 && sda == 0) { // START
bb->clock = clock_address;
bb->bits = 0;
bb->nbits = -1;
bb->sda_dev = 1;
bus->device = 0;
}
if (old_sda == 0 && sda == 1) { // STOP
bb->clock = 0;
bb->sda_dev = 1;
}
}
if (old_scl == 1 && scl == 0 && bb->clock)
bb->clock(bb);
return sda & bb->sda_dev;
}
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