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-rw-r--r--hw/i2c/i2c_mux_pca954x.c290
1 files changed, 290 insertions, 0 deletions
diff --git a/hw/i2c/i2c_mux_pca954x.c b/hw/i2c/i2c_mux_pca954x.c
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+/*
+ * 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)