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* QEMU I2C bus interface.
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* Copyright (c) 2007 CodeSourcery.
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* Written by Paul Brook
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* This code is licensed under the LGPL.
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#include "hw/i2c/i2c.h"
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I2CSlave *current_dev;
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uint8_t saved_address;
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static Property i2c_props[] = {
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DEFINE_PROP_UINT8("address", struct I2CSlave, address, 0),
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DEFINE_PROP_END_OF_LIST(),
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#define TYPE_I2C_BUS "i2c-bus"
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#define I2C_BUS(obj) OBJECT_CHECK(i2c_bus, (obj), TYPE_I2C_BUS)
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static const TypeInfo i2c_bus_info = {
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.instance_size = sizeof(i2c_bus),
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static void i2c_bus_pre_save(void *opaque)
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i2c_bus *bus = opaque;
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bus->saved_address = bus->current_dev ? bus->current_dev->address : -1;
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static int i2c_bus_post_load(void *opaque, int version_id)
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i2c_bus *bus = opaque;
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/* The bus is loaded before attached devices, so load and save the
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current device id. Devices will check themselves as loaded. */
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bus->current_dev = NULL;
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static const VMStateDescription vmstate_i2c_bus = {
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.minimum_version_id = 1,
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.minimum_version_id_old = 1,
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.pre_save = i2c_bus_pre_save,
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.post_load = i2c_bus_post_load,
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.fields = (VMStateField []) {
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VMSTATE_UINT8(saved_address, i2c_bus),
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/* Create a new I2C bus. */
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i2c_bus *i2c_init_bus(DeviceState *parent, const char *name)
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bus = FROM_QBUS(i2c_bus, qbus_create(TYPE_I2C_BUS, parent, name));
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vmstate_register(NULL, -1, &vmstate_i2c_bus, bus);
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void i2c_set_slave_address(I2CSlave *dev, uint8_t address)
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dev->address = address;
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/* Return nonzero if bus is busy. */
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int i2c_bus_busy(i2c_bus *bus)
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return bus->current_dev != NULL;
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/* Returns non-zero if the address is not valid. */
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/* TODO: Make this handle multiple masters. */
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int i2c_start_transfer(i2c_bus *bus, uint8_t address, int recv)
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I2CSlave *slave = NULL;
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QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
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DeviceState *qdev = kid->child;
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I2CSlave *candidate = I2C_SLAVE(qdev);
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if (candidate->address == address) {
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sc = I2C_SLAVE_GET_CLASS(slave);
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/* If the bus is already busy, assume this is a repeated
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bus->current_dev = slave;
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sc->event(slave, recv ? I2C_START_RECV : I2C_START_SEND);
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void i2c_end_transfer(i2c_bus *bus)
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I2CSlave *dev = bus->current_dev;
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sc = I2C_SLAVE_GET_CLASS(dev);
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sc->event(dev, I2C_FINISH);
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bus->current_dev = NULL;
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int i2c_send(i2c_bus *bus, uint8_t data)
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I2CSlave *dev = bus->current_dev;
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sc = I2C_SLAVE_GET_CLASS(dev);
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return sc->send(dev, data);
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int i2c_recv(i2c_bus *bus)
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I2CSlave *dev = bus->current_dev;
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sc = I2C_SLAVE_GET_CLASS(dev);
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return sc->recv(dev);
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void i2c_nack(i2c_bus *bus)
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I2CSlave *dev = bus->current_dev;
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sc = I2C_SLAVE_GET_CLASS(dev);
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sc->event(dev, I2C_NACK);
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static int i2c_slave_post_load(void *opaque, int version_id)
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I2CSlave *dev = opaque;
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bus = FROM_QBUS(i2c_bus, qdev_get_parent_bus(&dev->qdev));
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if (bus->saved_address == dev->address) {
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bus->current_dev = dev;
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const VMStateDescription vmstate_i2c_slave = {
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.minimum_version_id = 1,
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.minimum_version_id_old = 1,
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.post_load = i2c_slave_post_load,
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.fields = (VMStateField []) {
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VMSTATE_UINT8(address, I2CSlave),
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VMSTATE_END_OF_LIST()
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static int i2c_slave_qdev_init(DeviceState *dev)
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I2CSlave *s = I2C_SLAVE(dev);
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I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(s);
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DeviceState *i2c_create_slave(i2c_bus *bus, const char *name, uint8_t addr)
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dev = qdev_create(&bus->qbus, name);
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qdev_prop_set_uint8(dev, "address", addr);
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qdev_init_nofail(dev);
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static void i2c_slave_class_init(ObjectClass *klass, void *data)
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DeviceClass *k = DEVICE_CLASS(klass);
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k->init = i2c_slave_qdev_init;
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k->bus_type = TYPE_I2C_BUS;
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k->props = i2c_props;
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static const TypeInfo i2c_slave_type_info = {
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.name = TYPE_I2C_SLAVE,
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.parent = TYPE_DEVICE,
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.instance_size = sizeof(I2CSlave),
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.class_size = sizeof(I2CSlaveClass),
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.class_init = i2c_slave_class_init,
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static void i2c_slave_register_types(void)
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type_register_static(&i2c_bus_info);
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type_register_static(&i2c_slave_type_info);
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type_init(i2c_slave_register_types)