/* * 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" #include "hw/qdev-properties.h" #include "migration/vmstate.h" #include "qapi/error.h" #include "qemu/module.h" #include "trace.h" #define I2C_BROADCAST 0x00 static Property i2c_props[] = { DEFINE_PROP_UINT8("address", struct I2CSlave, address, 0), DEFINE_PROP_END_OF_LIST(), }; static const TypeInfo i2c_bus_info = { .name = TYPE_I2C_BUS, .parent = TYPE_BUS, .instance_size = sizeof(I2CBus), }; static int 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; } } return 0; } 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_new(TYPE_I2C_BUS, parent, name)); QLIST_INIT(&bus->current_devs); vmstate_register(NULL, VMSTATE_INSTANCE_ID_ANY, &vmstate_i2c_bus, bus); return bus; } void i2c_slave_set_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); } bool i2c_scan_bus(I2CBus *bus, uint8_t address, bool broadcast, I2CNodeList *current_devs) { BusChild *kid; QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) { DeviceState *qdev = kid->child; I2CSlave *candidate = I2C_SLAVE(qdev); I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(candidate); if (sc->match_and_add(candidate, address, broadcast, current_devs)) { if (!broadcast) { return true; } } } /* * If broadcast was true, and the list was full or empty, return true. If * broadcast was false, return false. */ return broadcast; } /* 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. * * @event must be I2C_START_RECV or I2C_START_SEND. */ static int i2c_do_start_transfer(I2CBus *bus, uint8_t address, enum i2c_event event) { 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; } /* * 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)) { /* Disregard whether devices were found. */ (void)i2c_scan_bus(bus, address, bus->broadcast, &bus->current_devs); bus_scanned = true; } if (QLIST_EMPTY(&bus->current_devs)) { return 1; } QLIST_FOREACH(node, &bus->current_devs, next) { I2CSlave *s = node->elt; int rv; sc = I2C_SLAVE_GET_CLASS(s); /* If the bus is already busy, assume this is a repeated start condition. */ if (sc->event) { trace_i2c_event("start", s->address); rv = sc->event(s, event); if (rv && !bus->broadcast) { if (bus_scanned) { /* First call, terminate the transfer. */ i2c_end_transfer(bus); } return rv; } } } return 0; } int i2c_start_transfer(I2CBus *bus, uint8_t address, bool is_recv) { return i2c_do_start_transfer(bus, address, is_recv ? I2C_START_RECV : I2C_START_SEND); } int i2c_start_recv(I2CBus *bus, uint8_t address) { return i2c_do_start_transfer(bus, address, I2C_START_RECV); } int i2c_start_send(I2CBus *bus, uint8_t address) { return i2c_do_start_transfer(bus, address, I2C_START_SEND); } void i2c_end_transfer(I2CBus *bus) { I2CSlaveClass *sc; I2CNode *node, *next; QLIST_FOREACH_SAFE(node, &bus->current_devs, next, next) { I2CSlave *s = node->elt; sc = I2C_SLAVE_GET_CLASS(s); if (sc->event) { trace_i2c_event("finish", s->address); sc->event(s, I2C_FINISH); } QLIST_REMOVE(node, next); g_free(node); } bus->broadcast = false; } int i2c_send(I2CBus *bus, uint8_t data) { I2CSlaveClass *sc; I2CSlave *s; I2CNode *node; int ret = 0; QLIST_FOREACH(node, &bus->current_devs, next) { s = node->elt; sc = I2C_SLAVE_GET_CLASS(s); if (sc->send) { trace_i2c_send(s->address, data); ret = ret || sc->send(s, data); } else { ret = -1; } } return ret ? -1 : 0; } uint8_t i2c_recv(I2CBus *bus) { uint8_t data = 0xff; I2CSlaveClass *sc; I2CSlave *s; if (!QLIST_EMPTY(&bus->current_devs) && !bus->broadcast) { sc = I2C_SLAVE_GET_CLASS(QLIST_FIRST(&bus->current_devs)->elt); if (sc->recv) { s = QLIST_FIRST(&bus->current_devs)->elt; data = sc->recv(s); trace_i2c_recv(s->address, data); } } return 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) { trace_i2c_event("nack", node->elt->address); 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() } }; I2CSlave *i2c_slave_new(const char *name, uint8_t addr) { DeviceState *dev; dev = qdev_new(name); qdev_prop_set_uint8(dev, "address", addr); return I2C_SLAVE(dev); } bool i2c_slave_realize_and_unref(I2CSlave *dev, I2CBus *bus, Error **errp) { return qdev_realize_and_unref(&dev->qdev, &bus->qbus, errp); } I2CSlave *i2c_slave_create_simple(I2CBus *bus, const char *name, uint8_t addr) { I2CSlave *dev = i2c_slave_new(name, addr); i2c_slave_realize_and_unref(dev, bus, &error_abort); return dev; } static bool i2c_slave_match(I2CSlave *candidate, uint8_t address, bool broadcast, I2CNodeList *current_devs) { if ((candidate->address == address) || (broadcast)) { I2CNode *node = g_malloc(sizeof(struct I2CNode)); node->elt = candidate; QLIST_INSERT_HEAD(current_devs, node, next); return true; } /* Not found and not broadcast. */ return false; } static void i2c_slave_class_init(ObjectClass *klass, void *data) { DeviceClass *k = DEVICE_CLASS(klass); I2CSlaveClass *sc = I2C_SLAVE_CLASS(klass); set_bit(DEVICE_CATEGORY_MISC, k->categories); k->bus_type = TYPE_I2C_BUS; device_class_set_props(k, i2c_props); sc->match_and_add = i2c_slave_match; } 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)