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/*
* QEMU I2C bus interface.
*
* Copyright (c) 2007 CodeSourcery.
* Written by Paul Brook
*
* This code is licensed under the LGPL.
*/
#include "qemu/osdep.h"
#include "hw/i2c/i2c.h"
typedef struct I2CNode I2CNode;
struct I2CNode {
I2CSlave *elt;
QLIST_ENTRY(I2CNode) next;
};
#define I2C_BROADCAST 0x00
struct I2CBus
{
BusState qbus;
QLIST_HEAD(, I2CNode) current_devs;
uint8_t saved_address;
bool broadcast;
};
static Property i2c_props[] = {
DEFINE_PROP_UINT8("address", struct I2CSlave, address, 0),
DEFINE_PROP_END_OF_LIST(),
};
#define TYPE_I2C_BUS "i2c-bus"
#define I2C_BUS(obj) OBJECT_CHECK(I2CBus, (obj), TYPE_I2C_BUS)
static const TypeInfo i2c_bus_info = {
.name = TYPE_I2C_BUS,
.parent = TYPE_BUS,
.instance_size = sizeof(I2CBus),
};
static void i2c_bus_pre_save(void *opaque)
{
I2CBus *bus = opaque;
bus->saved_address = -1;
if (!QLIST_EMPTY(&bus->current_devs)) {
if (!bus->broadcast) {
bus->saved_address = QLIST_FIRST(&bus->current_devs)->elt->address;
} else {
bus->saved_address = I2C_BROADCAST;
}
}
}
static const VMStateDescription vmstate_i2c_bus = {
.name = "i2c_bus",
.version_id = 1,
.minimum_version_id = 1,
.pre_save = i2c_bus_pre_save,
.fields = (VMStateField[]) {
VMSTATE_UINT8(saved_address, I2CBus),
VMSTATE_END_OF_LIST()
}
};
/* Create a new I2C bus. */
I2CBus *i2c_init_bus(DeviceState *parent, const char *name)
{
I2CBus *bus;
bus = I2C_BUS(qbus_create(TYPE_I2C_BUS, parent, name));
QLIST_INIT(&bus->current_devs);
vmstate_register(NULL, -1, &vmstate_i2c_bus, bus);
return bus;
}
void i2c_set_slave_address(I2CSlave *dev, uint8_t address)
{
dev->address = address;
}
/* Return nonzero if bus is busy. */
int i2c_bus_busy(I2CBus *bus)
{
return !QLIST_EMPTY(&bus->current_devs);
}
/* TODO: Make this handle multiple masters. */
/*
* Start or continue an i2c transaction. When this is called for the
* first time or after an i2c_end_transfer(), if it returns an error
* the bus transaction is terminated (or really never started). If
* this is called after another i2c_start_transfer() without an
* intervening i2c_end_transfer(), and it returns an error, the
* transaction will not be terminated. The caller must do it.
*
* This corresponds with the way real hardware works. The SMBus
* protocol uses a start transfer to switch from write to read mode
* without releasing the bus. If that fails, the bus is still
* in a transaction.
*/
int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv)
{
BusChild *kid;
I2CSlaveClass *sc;
I2CNode *node;
bool bus_scanned = false;
if (address == I2C_BROADCAST) {
/*
* This is a broadcast, the current_devs will be all the devices of the
* bus.
*/
bus->broadcast = true;
}
/*
* If there are already devices in the list, that means we are in
* the middle of a transaction and we shouldn't rescan the bus.
*
* This happens with any SMBus transaction, even on a pure I2C
* device. The interface does a transaction start without
* terminating the previous transaction.
*/
if (QLIST_EMPTY(&bus->current_devs)) {
QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
DeviceState *qdev = kid->child;
I2CSlave *candidate = I2C_SLAVE(qdev);
if ((candidate->address == address) || (bus->broadcast)) {
node = g_malloc(sizeof(struct I2CNode));
node->elt = candidate;
QLIST_INSERT_HEAD(&bus->current_devs, node, next);
if (!bus->broadcast) {
break;
}
}
}
bus_scanned = true;
}
if (QLIST_EMPTY(&bus->current_devs)) {
return 1;
}
QLIST_FOREACH(node, &bus->current_devs, next) {
int rv;
sc = I2C_SLAVE_GET_CLASS(node->elt);
/* If the bus is already busy, assume this is a repeated
start condition. */
if (sc->event) {
rv = sc->event(node->elt, recv ? I2C_START_RECV : I2C_START_SEND);
if (rv && !bus->broadcast) {
if (bus_scanned) {
/* First call, terminate the transfer. */
i2c_end_transfer(bus);
}
return rv;
}
}
}
return 0;
}
void i2c_end_transfer(I2CBus *bus)
{
I2CSlaveClass *sc;
I2CNode *node, *next;
QLIST_FOREACH_SAFE(node, &bus->current_devs, next, next) {
sc = I2C_SLAVE_GET_CLASS(node->elt);
if (sc->event) {
sc->event(node->elt, I2C_FINISH);
}
QLIST_REMOVE(node, next);
g_free(node);
}
bus->broadcast = false;
}
int i2c_send_recv(I2CBus *bus, uint8_t *data, bool send)
{
I2CSlaveClass *sc;
I2CNode *node;
int ret = 0;
if (send) {
QLIST_FOREACH(node, &bus->current_devs, next) {
sc = I2C_SLAVE_GET_CLASS(node->elt);
if (sc->send) {
ret = ret || sc->send(node->elt, *data);
} else {
ret = -1;
}
}
return ret ? -1 : 0;
} else {
if ((QLIST_EMPTY(&bus->current_devs)) || (bus->broadcast)) {
return -1;
}
sc = I2C_SLAVE_GET_CLASS(QLIST_FIRST(&bus->current_devs)->elt);
if (sc->recv) {
ret = sc->recv(QLIST_FIRST(&bus->current_devs)->elt);
if (ret < 0) {
return ret;
} else {
*data = ret;
return 0;
}
}
return -1;
}
}
int i2c_send(I2CBus *bus, uint8_t data)
{
return i2c_send_recv(bus, &data, true);
}
int i2c_recv(I2CBus *bus)
{
uint8_t data;
int ret = i2c_send_recv(bus, &data, false);
return ret < 0 ? ret : data;
}
void i2c_nack(I2CBus *bus)
{
I2CSlaveClass *sc;
I2CNode *node;
if (QLIST_EMPTY(&bus->current_devs)) {
return;
}
QLIST_FOREACH(node, &bus->current_devs, next) {
sc = I2C_SLAVE_GET_CLASS(node->elt);
if (sc->event) {
sc->event(node->elt, I2C_NACK);
}
}
}
static int i2c_slave_post_load(void *opaque, int version_id)
{
I2CSlave *dev = opaque;
I2CBus *bus;
I2CNode *node;
bus = I2C_BUS(qdev_get_parent_bus(DEVICE(dev)));
if ((bus->saved_address == dev->address) ||
(bus->saved_address == I2C_BROADCAST)) {
node = g_malloc(sizeof(struct I2CNode));
node->elt = dev;
QLIST_INSERT_HEAD(&bus->current_devs, node, next);
}
return 0;
}
const VMStateDescription vmstate_i2c_slave = {
.name = "I2CSlave",
.version_id = 1,
.minimum_version_id = 1,
.post_load = i2c_slave_post_load,
.fields = (VMStateField[]) {
VMSTATE_UINT8(address, I2CSlave),
VMSTATE_END_OF_LIST()
}
};
static int i2c_slave_qdev_init(DeviceState *dev)
{
I2CSlave *s = I2C_SLAVE(dev);
I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(s);
if (sc->init) {
return sc->init(s);
}
return 0;
}
DeviceState *i2c_create_slave(I2CBus *bus, const char *name, uint8_t addr)
{
DeviceState *dev;
dev = qdev_create(&bus->qbus, name);
qdev_prop_set_uint8(dev, "address", addr);
qdev_init_nofail(dev);
return dev;
}
static void i2c_slave_class_init(ObjectClass *klass, void *data)
{
DeviceClass *k = DEVICE_CLASS(klass);
k->init = i2c_slave_qdev_init;
set_bit(DEVICE_CATEGORY_MISC, k->categories);
k->bus_type = TYPE_I2C_BUS;
k->props = i2c_props;
}
static const TypeInfo i2c_slave_type_info = {
.name = TYPE_I2C_SLAVE,
.parent = TYPE_DEVICE,
.instance_size = sizeof(I2CSlave),
.abstract = true,
.class_size = sizeof(I2CSlaveClass),
.class_init = i2c_slave_class_init,
};
static void i2c_slave_register_types(void)
{
type_register_static(&i2c_bus_info);
type_register_static(&i2c_slave_type_info);
}
type_init(i2c_slave_register_types)
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