1 /* 2 * QEMU I2C bus interface. 3 * 4 * Copyright (c) 2007 CodeSourcery. 5 * Written by Paul Brook 6 * 7 * This code is licensed under the LGPL. 8 */ 9 10 #include "hw/i2c/i2c.h" 11 12 struct I2CBus 13 { 14 BusState qbus; 15 I2CSlave *current_dev; 16 I2CSlave *dev; 17 uint8_t saved_address; 18 }; 19 20 static Property i2c_props[] = { 21 DEFINE_PROP_UINT8("address", struct I2CSlave, address, 0), 22 DEFINE_PROP_END_OF_LIST(), 23 }; 24 25 #define TYPE_I2C_BUS "i2c-bus" 26 #define I2C_BUS(obj) OBJECT_CHECK(I2CBus, (obj), TYPE_I2C_BUS) 27 28 static const TypeInfo i2c_bus_info = { 29 .name = TYPE_I2C_BUS, 30 .parent = TYPE_BUS, 31 .instance_size = sizeof(I2CBus), 32 }; 33 34 static void i2c_bus_pre_save(void *opaque) 35 { 36 I2CBus *bus = opaque; 37 38 bus->saved_address = bus->current_dev ? bus->current_dev->address : -1; 39 } 40 41 static int i2c_bus_post_load(void *opaque, int version_id) 42 { 43 I2CBus *bus = opaque; 44 45 /* The bus is loaded before attached devices, so load and save the 46 current device id. Devices will check themselves as loaded. */ 47 bus->current_dev = NULL; 48 return 0; 49 } 50 51 static const VMStateDescription vmstate_i2c_bus = { 52 .name = "i2c_bus", 53 .version_id = 1, 54 .minimum_version_id = 1, 55 .minimum_version_id_old = 1, 56 .pre_save = i2c_bus_pre_save, 57 .post_load = i2c_bus_post_load, 58 .fields = (VMStateField []) { 59 VMSTATE_UINT8(saved_address, I2CBus), 60 VMSTATE_END_OF_LIST() 61 } 62 }; 63 64 /* Create a new I2C bus. */ 65 I2CBus *i2c_init_bus(DeviceState *parent, const char *name) 66 { 67 I2CBus *bus; 68 69 bus = I2C_BUS(qbus_create(TYPE_I2C_BUS, parent, name)); 70 vmstate_register(NULL, -1, &vmstate_i2c_bus, bus); 71 return bus; 72 } 73 74 void i2c_set_slave_address(I2CSlave *dev, uint8_t address) 75 { 76 dev->address = address; 77 } 78 79 /* Return nonzero if bus is busy. */ 80 int i2c_bus_busy(I2CBus *bus) 81 { 82 return bus->current_dev != NULL; 83 } 84 85 /* Returns non-zero if the address is not valid. */ 86 /* TODO: Make this handle multiple masters. */ 87 int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv) 88 { 89 BusChild *kid; 90 I2CSlave *slave = NULL; 91 I2CSlaveClass *sc; 92 93 QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) { 94 DeviceState *qdev = kid->child; 95 I2CSlave *candidate = I2C_SLAVE(qdev); 96 if (candidate->address == address) { 97 slave = candidate; 98 break; 99 } 100 } 101 102 if (!slave) { 103 return 1; 104 } 105 106 sc = I2C_SLAVE_GET_CLASS(slave); 107 /* If the bus is already busy, assume this is a repeated 108 start condition. */ 109 bus->current_dev = slave; 110 if (sc->event) { 111 sc->event(slave, recv ? I2C_START_RECV : I2C_START_SEND); 112 } 113 return 0; 114 } 115 116 void i2c_end_transfer(I2CBus *bus) 117 { 118 I2CSlave *dev = bus->current_dev; 119 I2CSlaveClass *sc; 120 121 if (!dev) { 122 return; 123 } 124 125 sc = I2C_SLAVE_GET_CLASS(dev); 126 if (sc->event) { 127 sc->event(dev, I2C_FINISH); 128 } 129 130 bus->current_dev = NULL; 131 } 132 133 int i2c_send(I2CBus *bus, uint8_t data) 134 { 135 I2CSlave *dev = bus->current_dev; 136 I2CSlaveClass *sc; 137 138 if (!dev) { 139 return -1; 140 } 141 142 sc = I2C_SLAVE_GET_CLASS(dev); 143 if (sc->send) { 144 return sc->send(dev, data); 145 } 146 147 return -1; 148 } 149 150 int i2c_recv(I2CBus *bus) 151 { 152 I2CSlave *dev = bus->current_dev; 153 I2CSlaveClass *sc; 154 155 if (!dev) { 156 return -1; 157 } 158 159 sc = I2C_SLAVE_GET_CLASS(dev); 160 if (sc->recv) { 161 return sc->recv(dev); 162 } 163 164 return -1; 165 } 166 167 void i2c_nack(I2CBus *bus) 168 { 169 I2CSlave *dev = bus->current_dev; 170 I2CSlaveClass *sc; 171 172 if (!dev) { 173 return; 174 } 175 176 sc = I2C_SLAVE_GET_CLASS(dev); 177 if (sc->event) { 178 sc->event(dev, I2C_NACK); 179 } 180 } 181 182 static int i2c_slave_post_load(void *opaque, int version_id) 183 { 184 I2CSlave *dev = opaque; 185 I2CBus *bus; 186 bus = I2C_BUS(qdev_get_parent_bus(DEVICE(dev))); 187 if (bus->saved_address == dev->address) { 188 bus->current_dev = dev; 189 } 190 return 0; 191 } 192 193 const VMStateDescription vmstate_i2c_slave = { 194 .name = "I2CSlave", 195 .version_id = 1, 196 .minimum_version_id = 1, 197 .minimum_version_id_old = 1, 198 .post_load = i2c_slave_post_load, 199 .fields = (VMStateField []) { 200 VMSTATE_UINT8(address, I2CSlave), 201 VMSTATE_END_OF_LIST() 202 } 203 }; 204 205 static int i2c_slave_qdev_init(DeviceState *dev) 206 { 207 I2CSlave *s = I2C_SLAVE(dev); 208 I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(s); 209 210 return sc->init(s); 211 } 212 213 DeviceState *i2c_create_slave(I2CBus *bus, const char *name, uint8_t addr) 214 { 215 DeviceState *dev; 216 217 dev = qdev_create(&bus->qbus, name); 218 qdev_prop_set_uint8(dev, "address", addr); 219 qdev_init_nofail(dev); 220 return dev; 221 } 222 223 static void i2c_slave_class_init(ObjectClass *klass, void *data) 224 { 225 DeviceClass *k = DEVICE_CLASS(klass); 226 k->init = i2c_slave_qdev_init; 227 set_bit(DEVICE_CATEGORY_MISC, k->categories); 228 k->bus_type = TYPE_I2C_BUS; 229 k->props = i2c_props; 230 } 231 232 static const TypeInfo i2c_slave_type_info = { 233 .name = TYPE_I2C_SLAVE, 234 .parent = TYPE_DEVICE, 235 .instance_size = sizeof(I2CSlave), 236 .abstract = true, 237 .class_size = sizeof(I2CSlaveClass), 238 .class_init = i2c_slave_class_init, 239 }; 240 241 static void i2c_slave_register_types(void) 242 { 243 type_register_static(&i2c_bus_info); 244 type_register_static(&i2c_slave_type_info); 245 } 246 247 type_init(i2c_slave_register_types) 248