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i2c: implement broadcast write
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This does a write to every slaves when the I2C bus get a write to address 0.

Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com>
Reviewed-by: Alistair Francis <alistair.francis@xilinx.com>
Reviewed-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
Tested-By: Hyun Kwon <hyun.kwon@xilinx.com>
Message-id: 1465833014-21982-3-git-send-email-fred.konrad@greensocs.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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@konrad-fred @pm215
konrad-fred authored and pm215 committed Jun 14, 2016
1 parent a9d2f1d commit 2293c27
Showing 1 changed file with 79 additions and 55 deletions.
134 changes: 79 additions & 55 deletions hw/i2c/core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -10,11 +10,19 @@
#include "qemu/osdep.h"
#include "hw/i2c/i2c.h"

typedef struct I2CNode I2CNode;

struct I2CNode {
I2CSlave *elt;
QLIST_ENTRY(I2CNode) next;
};

struct I2CBus
{
BusState qbus;
I2CSlave *current_dev;
QLIST_HEAD(, I2CNode) current_devs;
uint8_t saved_address;
bool broadcast;
};

static Property i2c_props[] = {
Expand All @@ -35,27 +43,22 @@ static void i2c_bus_pre_save(void *opaque)
{
I2CBus *bus = opaque;

bus->saved_address = bus->current_dev ? bus->current_dev->address : -1;
}

static int i2c_bus_post_load(void *opaque, int version_id)
{
I2CBus *bus = opaque;

/* The bus is loaded before attached devices, so load and save the
current device id. Devices will check themselves as loaded. */
bus->current_dev = NULL;
return 0;
bus->saved_address = -1;
if (!QLIST_EMPTY(&bus->current_devs)) {
if (!bus->broadcast) {
bus->saved_address = QLIST_FIRST(&bus->current_devs)->elt->address;
}
}
}

static const VMStateDescription vmstate_i2c_bus = {
.name = "i2c_bus",
.version_id = 1,
.minimum_version_id = 1,
.pre_save = i2c_bus_pre_save,
.post_load = i2c_bus_post_load,
.fields = (VMStateField[]) {
VMSTATE_UINT8(saved_address, I2CBus),
VMSTATE_BOOL(broadcast, I2CBus),
VMSTATE_END_OF_LIST()
}
};
Expand All @@ -66,6 +69,7 @@ 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;
}
Expand All @@ -78,113 +82,133 @@ void i2c_set_slave_address(I2CSlave *dev, uint8_t address)
/* Return nonzero if bus is busy. */
int i2c_bus_busy(I2CBus *bus)
{
return bus->current_dev != NULL;
return !QLIST_EMPTY(&bus->current_devs);
}

/* Returns non-zero if the address is not valid. */
/* TODO: Make this handle multiple masters. */
int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv)
{
BusChild *kid;
I2CSlave *slave = NULL;
I2CSlaveClass *sc;
I2CNode *node;

if (address == 0x00) {
/*
* This is a broadcast, the current_devs will be all the devices of the
* bus.
*/
bus->broadcast = true;
}

QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
DeviceState *qdev = kid->child;
I2CSlave *candidate = I2C_SLAVE(qdev);
if (candidate->address == address) {
slave = candidate;
break;
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;
}
}
}

if (!slave) {
if (QLIST_EMPTY(&bus->current_devs)) {
return 1;
}

sc = I2C_SLAVE_GET_CLASS(slave);
/* If the bus is already busy, assume this is a repeated
start condition. */
bus->current_dev = slave;
if (sc->event) {
sc->event(slave, recv ? I2C_START_RECV : I2C_START_SEND);
QLIST_FOREACH(node, &bus->current_devs, next) {
sc = I2C_SLAVE_GET_CLASS(node->elt);
/* If the bus is already busy, assume this is a repeated
start condition. */
if (sc->event) {
sc->event(node->elt, recv ? I2C_START_RECV : I2C_START_SEND);
}
}
return 0;
}

void i2c_end_transfer(I2CBus *bus)
{
I2CSlave *dev = bus->current_dev;
I2CSlaveClass *sc;
I2CNode *node, *next;

if (!dev) {
if (QLIST_EMPTY(&bus->current_devs)) {
return;
}

sc = I2C_SLAVE_GET_CLASS(dev);
if (sc->event) {
sc->event(dev, I2C_FINISH);
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->current_dev = NULL;
bus->broadcast = false;
}

int i2c_send(I2CBus *bus, uint8_t data)
{
I2CSlave *dev = bus->current_dev;
I2CSlaveClass *sc;

if (!dev) {
return -1;
}

sc = I2C_SLAVE_GET_CLASS(dev);
if (sc->send) {
return sc->send(dev, data);
I2CNode *node;
int ret = 0;

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 -1;
return ret ? -1 : 0;
}

int i2c_recv(I2CBus *bus)
{
I2CSlave *dev = bus->current_dev;
I2CSlaveClass *sc;

if (!dev) {
if ((QLIST_EMPTY(&bus->current_devs)) || (bus->broadcast)) {
return -1;
}

sc = I2C_SLAVE_GET_CLASS(dev);
sc = I2C_SLAVE_GET_CLASS(QLIST_FIRST(&bus->current_devs)->elt);
if (sc->recv) {
return sc->recv(dev);
return sc->recv(QLIST_FIRST(&bus->current_devs)->elt);
}

return -1;
}

void i2c_nack(I2CBus *bus)
{
I2CSlave *dev = bus->current_dev;
I2CSlaveClass *sc;
I2CNode *node;

if (!dev) {
if (QLIST_EMPTY(&bus->current_devs)) {
return;
}

sc = I2C_SLAVE_GET_CLASS(dev);
if (sc->event) {
sc->event(dev, I2C_NACK);
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->current_dev = dev;
if ((bus->saved_address == dev->address) || (bus->broadcast)) {
node = g_malloc(sizeof(struct I2CNode));
node->elt = dev;
QLIST_INSERT_HEAD(&bus->current_devs, node, next);
}
return 0;
}
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