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 .pre_save = i2c_bus_pre_save, 56 .post_load = i2c_bus_post_load, 57 .fields = (VMStateField[]) { 58 VMSTATE_UINT8(saved_address, I2CBus), 59 VMSTATE_END_OF_LIST() 60 } 61 }; 62 63 /* Create a new I2C bus. */ 64 I2CBus *i2c_init_bus(DeviceState *parent, const char *name) 65 { 66 I2CBus *bus; 67 68 bus = I2C_BUS(qbus_create(TYPE_I2C_BUS, parent, name)); 69 vmstate_register(NULL, -1, &vmstate_i2c_bus, bus); 70 return bus; 71 } 72 73 void i2c_set_slave_address(I2CSlave *dev, uint8_t address) 74 { 75 dev->address = address; 76 } 77 78 /* Return nonzero if bus is busy. */ 79 int i2c_bus_busy(I2CBus *bus) 80 { 81 return bus->current_dev != NULL; 82 } 83 84 /* Returns non-zero if the address is not valid. */ 85 /* TODO: Make this handle multiple masters. */ 86 int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv) 87 { 88 BusChild *kid; 89 I2CSlave *slave = NULL; 90 I2CSlaveClass *sc; 91 92 QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) { 93 DeviceState *qdev = kid->child; 94 I2CSlave *candidate = I2C_SLAVE(qdev); 95 if (candidate->address == address) { 96 slave = candidate; 97 break; 98 } 99 } 100 101 if (!slave) { 102 return 1; 103 } 104 105 sc = I2C_SLAVE_GET_CLASS(slave); 106 /* If the bus is already busy, assume this is a repeated 107 start condition. */ 108 bus->current_dev = slave; 109 if (sc->event) { 110 sc->event(slave, recv ? I2C_START_RECV : I2C_START_SEND); 111 } 112 return 0; 113 } 114 115 void i2c_end_transfer(I2CBus *bus) 116 { 117 I2CSlave *dev = bus->current_dev; 118 I2CSlaveClass *sc; 119 120 if (!dev) { 121 return; 122 } 123 124 sc = I2C_SLAVE_GET_CLASS(dev); 125 if (sc->event) { 126 sc->event(dev, I2C_FINISH); 127 } 128 129 bus->current_dev = NULL; 130 } 131 132 int i2c_send(I2CBus *bus, uint8_t data) 133 { 134 I2CSlave *dev = bus->current_dev; 135 I2CSlaveClass *sc; 136 137 if (!dev) { 138 return -1; 139 } 140 141 sc = I2C_SLAVE_GET_CLASS(dev); 142 if (sc->send) { 143 return sc->send(dev, data); 144 } 145 146 return -1; 147 } 148 149 int i2c_recv(I2CBus *bus) 150 { 151 I2CSlave *dev = bus->current_dev; 152 I2CSlaveClass *sc; 153 154 if (!dev) { 155 return -1; 156 } 157 158 sc = I2C_SLAVE_GET_CLASS(dev); 159 if (sc->recv) { 160 return sc->recv(dev); 161 } 162 163 return -1; 164 } 165 166 void i2c_nack(I2CBus *bus) 167 { 168 I2CSlave *dev = bus->current_dev; 169 I2CSlaveClass *sc; 170 171 if (!dev) { 172 return; 173 } 174 175 sc = I2C_SLAVE_GET_CLASS(dev); 176 if (sc->event) { 177 sc->event(dev, I2C_NACK); 178 } 179 } 180 181 static int i2c_slave_post_load(void *opaque, int version_id) 182 { 183 I2CSlave *dev = opaque; 184 I2CBus *bus; 185 bus = I2C_BUS(qdev_get_parent_bus(DEVICE(dev))); 186 if (bus->saved_address == dev->address) { 187 bus->current_dev = dev; 188 } 189 return 0; 190 } 191 192 const VMStateDescription vmstate_i2c_slave = { 193 .name = "I2CSlave", 194 .version_id = 1, 195 .minimum_version_id = 1, 196 .post_load = i2c_slave_post_load, 197 .fields = (VMStateField[]) { 198 VMSTATE_UINT8(address, I2CSlave), 199 VMSTATE_END_OF_LIST() 200 } 201 }; 202 203 static int i2c_slave_qdev_init(DeviceState *dev) 204 { 205 I2CSlave *s = I2C_SLAVE(dev); 206 I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(s); 207 208 return sc->init(s); 209 } 210 211 DeviceState *i2c_create_slave(I2CBus *bus, const char *name, uint8_t addr) 212 { 213 DeviceState *dev; 214 215 dev = qdev_create(&bus->qbus, name); 216 qdev_prop_set_uint8(dev, "address", addr); 217 qdev_init_nofail(dev); 218 return dev; 219 } 220 221 static void i2c_slave_class_init(ObjectClass *klass, void *data) 222 { 223 DeviceClass *k = DEVICE_CLASS(klass); 224 k->init = i2c_slave_qdev_init; 225 set_bit(DEVICE_CATEGORY_MISC, k->categories); 226 k->bus_type = TYPE_I2C_BUS; 227 k->props = i2c_props; 228 } 229 230 static const TypeInfo i2c_slave_type_info = { 231 .name = TYPE_I2C_SLAVE, 232 .parent = TYPE_DEVICE, 233 .instance_size = sizeof(I2CSlave), 234 .abstract = true, 235 .class_size = sizeof(I2CSlaveClass), 236 .class_init = i2c_slave_class_init, 237 }; 238 239 static void i2c_slave_register_types(void) 240 { 241 type_register_static(&i2c_bus_info); 242 type_register_static(&i2c_slave_type_info); 243 } 244 245 type_init(i2c_slave_register_types) 246