qemu/hw/i2c/core.c

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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;
}
i2c: Fix SMBus read transactions to avoid double events Change 2293c27faddf (i2c: implement broadcast write) added broadcast capability to the I2C bus, but it broke SMBus read transactions. An SMBus read transaction does two i2c_start_transaction() calls without an intervening i2c_end_transfer() call. This will result in i2c_start_transfer() adding the same device to the current_devs list twice, and then the ->event() for the same device gets called twice in the second call to i2c_start_transfer(), resulting in the smbus code getting confused. Note that this happens even with pure I2C devices when simulating SMBus over I2C. This fix only scans the bus if the current set of devices is empty. This means that the current set of devices stays fixed until i2c_end_transfer() is called, which is really what you want. This also deletes the empty check from the top of i2c_end_transfer(). It's unnecessary, and it prevents the broadcast variable from being set to false at the end of the transaction if no devices were on the bus. Cc: KONRAD Frederic <fred.konrad@greensocs.com> Cc: Alistair Francis <alistair.francis@xilinx.com> Cc: Peter Crosthwaite <crosthwaite.peter@gmail.com> Cc: Kwon <hyun.kwon@xilinx.com> Cc: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Corey Minyard <cminyard@mvista.com> Reviewed-by: KONRAD Frederic <fred.konrad@greensocs.com> Tested-by: KONRAD Frederic <fred.konrad@greensocs.com> Message-id: 1470153614-6657-1-git-send-email-minyard@acm.org Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2016-10-24 18:26:55 +03:00
/*
* 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)