qemu

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/*
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 * QEMU I2C bus interface.
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 *
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 * Copyright (c) 2007 CodeSourcery.
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 * Written by Paul Brook
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 *
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 * This code is licensed under the LGPL.
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 */
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#include "qemu/osdep.h"
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#include "hw/i2c/i2c.h"
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#include "hw/qdev-properties.h"
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#include "migration/vmstate.h"
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#include "qapi/error.h"
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#include "qemu/module.h"
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#include "qemu/main-loop.h"
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#include "trace.h"
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#define I2C_BROADCAST 0x00
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static Property i2c_props[] = {
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    DEFINE_PROP_UINT8("address", struct I2CSlave, address, 0),
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    DEFINE_PROP_END_OF_LIST(),
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};
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static const TypeInfo i2c_bus_info = {
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    .name = TYPE_I2C_BUS,
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    .parent = TYPE_BUS,
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    .instance_size = sizeof(I2CBus),
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};
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static int i2c_bus_pre_save(void *opaque)
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{
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    I2CBus *bus = opaque;
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    bus->saved_address = -1;
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    if (!QLIST_EMPTY(&bus->current_devs)) {
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        if (!bus->broadcast) {
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            bus->saved_address = QLIST_FIRST(&bus->current_devs)->elt->address;
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        } else {
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            bus->saved_address = I2C_BROADCAST;
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        }
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    }
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    return 0;
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}
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static const VMStateDescription vmstate_i2c_bus = {
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    .name = "i2c_bus",
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    .version_id = 1,
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    .minimum_version_id = 1,
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    .pre_save = i2c_bus_pre_save,
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    .fields = (const VMStateField[]) {
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        VMSTATE_UINT8(saved_address, I2CBus),
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        VMSTATE_END_OF_LIST()
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    }
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};
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/* Create a new I2C bus.  */
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I2CBus *i2c_init_bus(DeviceState *parent, const char *name)
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{
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    I2CBus *bus;
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    bus = I2C_BUS(qbus_new(TYPE_I2C_BUS, parent, name));
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    QLIST_INIT(&bus->current_devs);
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    QSIMPLEQ_INIT(&bus->pending_masters);
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    vmstate_register_any(NULL, &vmstate_i2c_bus, bus);
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    return bus;
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}
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void i2c_slave_set_address(I2CSlave *dev, uint8_t address)
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{
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    dev->address = address;
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}
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/* Return nonzero if bus is busy.  */
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int i2c_bus_busy(I2CBus *bus)
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{
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    return !QLIST_EMPTY(&bus->current_devs) || bus->bh;
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}
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bool i2c_scan_bus(I2CBus *bus, uint8_t address, bool broadcast,
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                  I2CNodeList *current_devs)
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{
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    BusChild *kid;
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    QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
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        DeviceState *qdev = kid->child;
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        I2CSlave *candidate = I2C_SLAVE(qdev);
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        I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(candidate);
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        if (sc->match_and_add(candidate, address, broadcast, current_devs)) {
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            if (!broadcast) {
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                return true;
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            }
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        }
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    }
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    /*
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     * If broadcast was true, and the list was full or empty, return true. If
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     * broadcast was false, return false.
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     */
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    return broadcast;
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}
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/* TODO: Make this handle multiple masters.  */
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/*
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 * Start or continue an i2c transaction.  When this is called for the
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 * first time or after an i2c_end_transfer(), if it returns an error
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 * the bus transaction is terminated (or really never started).  If
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 * this is called after another i2c_start_transfer() without an
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 * intervening i2c_end_transfer(), and it returns an error, the
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 * transaction will not be terminated.  The caller must do it.
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 *
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 * This corresponds with the way real hardware works.  The SMBus
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 * protocol uses a start transfer to switch from write to read mode
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 * without releasing the bus.  If that fails, the bus is still
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 * in a transaction.
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 *
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 * @event must be I2C_START_RECV or I2C_START_SEND.
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 */
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static int i2c_do_start_transfer(I2CBus *bus, uint8_t address,
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                                 enum i2c_event event)
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{
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    I2CSlaveClass *sc;
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    I2CNode *node;
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    bool bus_scanned = false;
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    if (address == I2C_BROADCAST) {
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        /*
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         * This is a broadcast, the current_devs will be all the devices of the
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         * bus.
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         */
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        bus->broadcast = true;
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    }
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    /*
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     * If there are already devices in the list, that means we are in
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     * the middle of a transaction and we shouldn't rescan the bus.
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     *
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     * This happens with any SMBus transaction, even on a pure I2C
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     * device.  The interface does a transaction start without
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     * terminating the previous transaction.
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     */
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    if (QLIST_EMPTY(&bus->current_devs)) {
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        /* Disregard whether devices were found. */
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        (void)i2c_scan_bus(bus, address, bus->broadcast, &bus->current_devs);
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        bus_scanned = true;
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    }
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    if (QLIST_EMPTY(&bus->current_devs)) {
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        return 1;
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    }
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    QLIST_FOREACH(node, &bus->current_devs, next) {
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        I2CSlave *s = node->elt;
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        int rv;
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        sc = I2C_SLAVE_GET_CLASS(s);
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        /* If the bus is already busy, assume this is a repeated
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           start condition.  */
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        if (sc->event) {
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            trace_i2c_event(event == I2C_START_SEND ? "start" : "start_async",
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                            s->address);
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            rv = sc->event(s, event);
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            if (rv && !bus->broadcast) {
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                if (bus_scanned) {
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                    /* First call, terminate the transfer. */
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                    i2c_end_transfer(bus);
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                }
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                return rv;
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            }
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        }
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    }
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    return 0;
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}
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int i2c_start_transfer(I2CBus *bus, uint8_t address, bool is_recv)
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{
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    return i2c_do_start_transfer(bus, address, is_recv
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                                               ? I2C_START_RECV
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                                               : I2C_START_SEND);
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}
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void i2c_bus_master(I2CBus *bus, QEMUBH *bh)
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{
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    I2CPendingMaster *node = g_new(struct I2CPendingMaster, 1);
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    node->bh = bh;
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    QSIMPLEQ_INSERT_TAIL(&bus->pending_masters, node, entry);
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}
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void i2c_schedule_pending_master(I2CBus *bus)
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{
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    I2CPendingMaster *node;
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    if (i2c_bus_busy(bus)) {
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        /* someone is already controlling the bus; wait for it to release it */
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        return;
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    }
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    if (QSIMPLEQ_EMPTY(&bus->pending_masters)) {
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        return;
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    }
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    node = QSIMPLEQ_FIRST(&bus->pending_masters);
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    bus->bh = node->bh;
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    QSIMPLEQ_REMOVE_HEAD(&bus->pending_masters, entry);
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    g_free(node);
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    qemu_bh_schedule(bus->bh);
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}
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void i2c_bus_release(I2CBus *bus)
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{
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    bus->bh = NULL;
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    i2c_schedule_pending_master(bus);
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}
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int i2c_start_recv(I2CBus *bus, uint8_t address)
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{
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    return i2c_do_start_transfer(bus, address, I2C_START_RECV);
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}
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int i2c_start_send(I2CBus *bus, uint8_t address)
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{
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    return i2c_do_start_transfer(bus, address, I2C_START_SEND);
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}
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int i2c_start_send_async(I2CBus *bus, uint8_t address)
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{
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    return i2c_do_start_transfer(bus, address, I2C_START_SEND_ASYNC);
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}
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void i2c_end_transfer(I2CBus *bus)
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{
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    I2CSlaveClass *sc;
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    I2CNode *node, *next;
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    QLIST_FOREACH_SAFE(node, &bus->current_devs, next, next) {
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        I2CSlave *s = node->elt;
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        sc = I2C_SLAVE_GET_CLASS(s);
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        if (sc->event) {
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            trace_i2c_event("finish", s->address);
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            sc->event(s, I2C_FINISH);
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        }
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        QLIST_REMOVE(node, next);
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        g_free(node);
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    }
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    bus->broadcast = false;
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}
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int i2c_send(I2CBus *bus, uint8_t data)
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{
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    I2CSlaveClass *sc;
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    I2CSlave *s;
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    I2CNode *node;
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    int ret = 0;
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    QLIST_FOREACH(node, &bus->current_devs, next) {
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        s = node->elt;
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        sc = I2C_SLAVE_GET_CLASS(s);
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        if (sc->send) {
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            trace_i2c_send(s->address, data);
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            ret = ret || sc->send(s, data);
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        } else {
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            ret = -1;
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        }
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    }
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    return ret ? -1 : 0;
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}
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int i2c_send_async(I2CBus *bus, uint8_t data)
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{
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    I2CNode *node = QLIST_FIRST(&bus->current_devs);
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    I2CSlave *slave = node->elt;
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    I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(slave);
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    if (!sc->send_async) {
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        return -1;
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    }
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    trace_i2c_send_async(slave->address, data);
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    sc->send_async(slave, data);
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    return 0;
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}
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uint8_t i2c_recv(I2CBus *bus)
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{
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    uint8_t data = 0xff;
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    I2CSlaveClass *sc;
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    I2CSlave *s;
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    if (!QLIST_EMPTY(&bus->current_devs) && !bus->broadcast) {
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        sc = I2C_SLAVE_GET_CLASS(QLIST_FIRST(&bus->current_devs)->elt);
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        if (sc->recv) {
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            s = QLIST_FIRST(&bus->current_devs)->elt;
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            data = sc->recv(s);
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            trace_i2c_recv(s->address, data);
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        }
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    }
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    return data;
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}
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void i2c_nack(I2CBus *bus)
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{
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    I2CSlaveClass *sc;
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    I2CNode *node;
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    if (QLIST_EMPTY(&bus->current_devs)) {
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        return;
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    }
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    QLIST_FOREACH(node, &bus->current_devs, next) {
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        sc = I2C_SLAVE_GET_CLASS(node->elt);
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        if (sc->event) {
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            trace_i2c_event("nack", node->elt->address);
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            sc->event(node->elt, I2C_NACK);
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        }
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    }
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}
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void i2c_ack(I2CBus *bus)
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{
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    if (!bus->bh) {
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        return;
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    }
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    trace_i2c_ack();
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    qemu_bh_schedule(bus->bh);
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}
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static int i2c_slave_post_load(void *opaque, int version_id)
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{
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    I2CSlave *dev = opaque;
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    I2CBus *bus;
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    I2CNode *node;
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    bus = I2C_BUS(qdev_get_parent_bus(DEVICE(dev)));
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    if ((bus->saved_address == dev->address) ||
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        (bus->saved_address == I2C_BROADCAST)) {
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        node = g_new(struct I2CNode, 1);
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        node->elt = dev;
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        QLIST_INSERT_HEAD(&bus->current_devs, node, next);
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    }
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    return 0;
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}
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const VMStateDescription vmstate_i2c_slave = {
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    .name = "I2CSlave",
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    .version_id = 1,
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    .minimum_version_id = 1,
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    .post_load = i2c_slave_post_load,
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    .fields = (const VMStateField[]) {
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        VMSTATE_UINT8(address, I2CSlave),
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        VMSTATE_END_OF_LIST()
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    }
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};
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I2CSlave *i2c_slave_new(const char *name, uint8_t addr)
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{
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    DeviceState *dev;
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    dev = qdev_new(name);
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    qdev_prop_set_uint8(dev, "address", addr);
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    return I2C_SLAVE(dev);
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}
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bool i2c_slave_realize_and_unref(I2CSlave *dev, I2CBus *bus, Error **errp)
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{
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    return qdev_realize_and_unref(&dev->qdev, &bus->qbus, errp);
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}
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I2CSlave *i2c_slave_create_simple(I2CBus *bus, const char *name, uint8_t addr)
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{
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    I2CSlave *dev = i2c_slave_new(name, addr);
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    i2c_slave_realize_and_unref(dev, bus, &error_abort);
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    return dev;
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}
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static bool i2c_slave_match(I2CSlave *candidate, uint8_t address,
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                            bool broadcast, I2CNodeList *current_devs)
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{
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    if ((candidate->address == address) || (broadcast)) {
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        I2CNode *node = g_new(struct I2CNode, 1);
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        node->elt = candidate;
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        QLIST_INSERT_HEAD(current_devs, node, next);
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        return true;
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    }
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    /* Not found and not broadcast. */
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    return false;
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}
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static void i2c_slave_class_init(ObjectClass *klass, void *data)
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{
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    DeviceClass *k = DEVICE_CLASS(klass);
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    I2CSlaveClass *sc = I2C_SLAVE_CLASS(klass);
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    set_bit(DEVICE_CATEGORY_MISC, k->categories);
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    k->bus_type = TYPE_I2C_BUS;
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    device_class_set_props(k, i2c_props);
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    sc->match_and_add = i2c_slave_match;
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}
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static const TypeInfo i2c_slave_type_info = {
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    .name = TYPE_I2C_SLAVE,
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    .parent = TYPE_DEVICE,
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    .instance_size = sizeof(I2CSlave),
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    .abstract = true,
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    .class_size = sizeof(I2CSlaveClass),
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    .class_init = i2c_slave_class_init,
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};
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static void i2c_slave_register_types(void)
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{
426
    type_register_static(&i2c_bus_info);
427
    type_register_static(&i2c_slave_type_info);
428
}
429

430
type_init(i2c_slave_register_types)
431