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 "qemu/osdep.h" 11 #include "hw/i2c/i2c.h" 12 13 struct I2CBus 14 { 15 BusState qbus; 16 I2CSlave *current_dev; 17 I2CSlave *dev; 18 uint8_t saved_address; 19 }; 20 21 static Property i2c_props[] = { 22 DEFINE_PROP_UINT8("address", struct I2CSlave, address, 0), 23 DEFINE_PROP_END_OF_LIST(), 24 }; 25 26 #define TYPE_I2C_BUS "i2c-bus" 27 #define I2C_BUS(obj) OBJECT_CHECK(I2CBus, (obj), TYPE_I2C_BUS) 28 29 static const TypeInfo i2c_bus_info = { 30 .name = TYPE_I2C_BUS, 31 .parent = TYPE_BUS, 32 .instance_size = sizeof(I2CBus), 33 }; 34 35 static void i2c_bus_pre_save(void *opaque) 36 { 37 I2CBus *bus = opaque; 38 39 bus->saved_address = bus->current_dev ? bus->current_dev->address : -1; 40 } 41 42 static int i2c_bus_post_load(void *opaque, int version_id) 43 { 44 I2CBus *bus = opaque; 45 46 /* The bus is loaded before attached devices, so load and save the 47 current device id. Devices will check themselves as loaded. */ 48 bus->current_dev = NULL; 49 return 0; 50 } 51 52 static const VMStateDescription vmstate_i2c_bus = { 53 .name = "i2c_bus", 54 .version_id = 1, 55 .minimum_version_id = 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 .post_load = i2c_slave_post_load, 198 .fields = (VMStateField[]) { 199 VMSTATE_UINT8(address, I2CSlave), 200 VMSTATE_END_OF_LIST() 201 } 202 }; 203 204 static int i2c_slave_qdev_init(DeviceState *dev) 205 { 206 I2CSlave *s = I2C_SLAVE(dev); 207 I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(s); 208 209 return sc->init(s); 210 } 211 212 DeviceState *i2c_create_slave(I2CBus *bus, const char *name, uint8_t addr) 213 { 214 DeviceState *dev; 215 216 dev = qdev_create(&bus->qbus, name); 217 qdev_prop_set_uint8(dev, "address", addr); 218 qdev_init_nofail(dev); 219 return dev; 220 } 221 222 static void i2c_slave_class_init(ObjectClass *klass, void *data) 223 { 224 DeviceClass *k = DEVICE_CLASS(klass); 225 k->init = i2c_slave_qdev_init; 226 set_bit(DEVICE_CATEGORY_MISC, k->categories); 227 k->bus_type = TYPE_I2C_BUS; 228 k->props = i2c_props; 229 } 230 231 static const TypeInfo i2c_slave_type_info = { 232 .name = TYPE_I2C_SLAVE, 233 .parent = TYPE_DEVICE, 234 .instance_size = sizeof(I2CSlave), 235 .abstract = true, 236 .class_size = sizeof(I2CSlaveClass), 237 .class_init = i2c_slave_class_init, 238 }; 239 240 static void i2c_slave_register_types(void) 241 { 242 type_register_static(&i2c_bus_info); 243 type_register_static(&i2c_slave_type_info); 244 } 245 246 type_init(i2c_slave_register_types) 247