/*
* I2C multiplexer for PCA954x series of I2C multiplexer/switch chips.
*
* Copyright 2021 Google LLC
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "hw/i2c/i2c.h"
#include "hw/i2c/i2c_mux_pca954x.h"
#include "hw/i2c/smbus_slave.h"
#include "hw/qdev-core.h"
#include "hw/sysbus.h"
#include "qemu/log.h"
#include "qemu/module.h"
#include "qemu/queue.h"
#include "qom/object.h"
#include "trace.h"
#define PCA9548_CHANNEL_COUNT 8
#define PCA9546_CHANNEL_COUNT 4
/*
* struct Pca954xChannel - The i2c mux device will have N of these states
* that own the i2c channel bus.
* @bus: The owned channel bus.
* @enabled: Is this channel active?
*/
typedef struct Pca954xChannel {
SysBusDevice parent;
I2CBus *bus;
bool enabled;
} Pca954xChannel;
#define TYPE_PCA954X_CHANNEL "pca954x-channel"
#define PCA954X_CHANNEL(obj) \
OBJECT_CHECK(Pca954xChannel, (obj), TYPE_PCA954X_CHANNEL)
/*
* struct Pca954xState - The pca954x state object.
* @control: The value written to the mux control.
* @channel: The set of i2c channel buses that act as channels which own the
* i2c children.
*/
typedef struct Pca954xState {
SMBusDevice parent;
uint8_t control;
/* The channel i2c buses. */
Pca954xChannel channel[PCA9548_CHANNEL_COUNT];
} Pca954xState;
/*
* struct Pca954xClass - The pca954x class object.
* @nchans: The number of i2c channels this device has.
*/
typedef struct Pca954xClass {
SMBusDeviceClass parent;
uint8_t nchans;
} Pca954xClass;
#define TYPE_PCA954X "pca954x"
OBJECT_DECLARE_TYPE(Pca954xState, Pca954xClass, PCA954X)
/*
* For each channel, if it's enabled, recursively call match on those children.
*/
static bool pca954x_match(I2CSlave *candidate, uint8_t address,
bool broadcast,
I2CNodeList *current_devs)
{
Pca954xState *mux = PCA954X(candidate);
Pca954xClass *mc = PCA954X_GET_CLASS(mux);
int i;
/* They are talking to the mux itself (or all devices enabled). */
if ((candidate->address == address) || broadcast) {
I2CNode *node = g_malloc(sizeof(struct I2CNode));
node->elt = candidate;
QLIST_INSERT_HEAD(current_devs, node, next);
if (!broadcast) {
return true;
}
}
for (i = 0; i < mc->nchans; i++) {
if (!mux->channel[i].enabled) {
continue;
}
if (i2c_scan_bus(mux->channel[i].bus, address, broadcast,
current_devs)) {
if (!broadcast) {
return true;
}
}
}
/* If we arrived here we didn't find a match, return broadcast. */
return broadcast;
}
static void pca954x_enable_channel(Pca954xState *s, uint8_t enable_mask)
{
Pca954xClass *mc = PCA954X_GET_CLASS(s);
int i;
/*
* For each channel, check if their bit is set in enable_mask and if yes,
* enable it, otherwise disable, hide it.
*/
for (i = 0; i < mc->nchans; i++) {
if (enable_mask & (1 << i)) {
s->channel[i].enabled = true;
} else {
s->channel[i].enabled = false;
}
}
}
static void pca954x_write(Pca954xState *s, uint8_t data)
{
s->control = data;
pca954x_enable_channel(s, data);
trace_pca954x_write_bytes(data);
}
static int pca954x_write_data(SMBusDevice *d, uint8_t *buf, uint8_t len)
{
Pca954xState *s = PCA954X(d);
if (len == 0) {
qemu_log_mask(LOG_GUEST_ERROR, "%s: writing empty data\n", __func__);
return -1;
}
/*
* len should be 1, because they write one byte to enable/disable channels.
*/
if (len > 1) {
qemu_log_mask(LOG_GUEST_ERROR,
"%s: extra data after channel selection mask\n",
__func__);
return -1;
}
pca954x_write(s, buf[0]);
return 0;
}
static uint8_t pca954x_read_byte(SMBusDevice *d)
{
Pca954xState *s = PCA954X(d);
uint8_t data = s->control;
trace_pca954x_read_data(data);
return data;
}
static void pca954x_enter_reset(Object *obj, ResetType type)
{
Pca954xState *s = PCA954X(obj);
/* Reset will disable all channels. */
pca954x_write(s, 0);
}
I2CBus *pca954x_i2c_get_bus(I2CSlave *mux, uint8_t channel)
{
Pca954xClass *pc = PCA954X_GET_CLASS(mux);
Pca954xState *pca954x = PCA954X(mux);
g_assert(channel < pc->nchans);
return I2C_BUS(qdev_get_child_bus(DEVICE(&pca954x->channel[channel]),
"i2c-bus"));
}
static void pca954x_channel_init(Object *obj)
{
Pca954xChannel *s = PCA954X_CHANNEL(obj);
s->bus = i2c_init_bus(DEVICE(s), "i2c-bus");
/* Start all channels as disabled. */
s->enabled = false;
}
static void pca954x_channel_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
dc->desc = "Pca954x Channel";
}
static void pca9546_class_init(ObjectClass *klass, void *data)
{
Pca954xClass *s = PCA954X_CLASS(klass);
s->nchans = PCA9546_CHANNEL_COUNT;
}
static void pca9548_class_init(ObjectClass *klass, void *data)
{
Pca954xClass *s = PCA954X_CLASS(klass);
s->nchans = PCA9548_CHANNEL_COUNT;
}
static void pca954x_realize(DeviceState *dev, Error **errp)
{
Pca954xState *s = PCA954X(dev);
Pca954xClass *c = PCA954X_GET_CLASS(s);
int i;
/* SMBus modules. Cannot fail. */
for (i = 0; i < c->nchans; i++) {
sysbus_realize(SYS_BUS_DEVICE(&s->channel[i]), &error_abort);
}
}
static void pca954x_init(Object *obj)
{
Pca954xState *s = PCA954X(obj);
Pca954xClass *c = PCA954X_GET_CLASS(obj);
int i;
/* Only initialize the children we expect. */
for (i = 0; i < c->nchans; i++) {
object_initialize_child(obj, "channel[*]", &s->channel[i],
TYPE_PCA954X_CHANNEL);
}
}
static void pca954x_class_init(ObjectClass *klass, void *data)
{
I2CSlaveClass *sc = I2C_SLAVE_CLASS(klass);
ResettableClass *rc = RESETTABLE_CLASS(klass);
DeviceClass *dc = DEVICE_CLASS(klass);
SMBusDeviceClass *k = SMBUS_DEVICE_CLASS(klass);
sc->match_and_add = pca954x_match;
rc->phases.enter = pca954x_enter_reset;
dc->desc = "Pca954x i2c-mux";
dc->realize = pca954x_realize;
k->write_data = pca954x_write_data;
k->receive_byte = pca954x_read_byte;
}
static const TypeInfo pca954x_info[] = {
{
.name = TYPE_PCA954X,
.parent = TYPE_SMBUS_DEVICE,
.instance_size = sizeof(Pca954xState),
.instance_init = pca954x_init,
.class_size = sizeof(Pca954xClass),
.class_init = pca954x_class_init,
.abstract = true,
},
{
.name = TYPE_PCA9546,
.parent = TYPE_PCA954X,
.class_init = pca9546_class_init,
},
{
.name = TYPE_PCA9548,
.parent = TYPE_PCA954X,
.class_init = pca9548_class_init,
},
{
.name = TYPE_PCA954X_CHANNEL,
.parent = TYPE_SYS_BUS_DEVICE,
.class_init = pca954x_channel_class_init,
.instance_size = sizeof(Pca954xChannel),
.instance_init = pca954x_channel_init,
}
};
DEFINE_TYPES(pca954x_info)
