hw/i2c.c

   1 /*
   2  * QEMU I2C bus interface.
   3  *
   4  * Copyright (c) 2007 CodeSourcery.
   5  * Written by Paul Brook
   6  *
   7  * This code is licenced under the LGPL.
   8  */
   9
  10 #include "vl.h"
  11
  12 struct i2c_bus
  13 {
  14     i2c_slave *current_dev;
  15     i2c_slave *dev;
  16 };
  17
  18 /* Create a new I2C bus.  */
  19 i2c_bus *i2c_init_bus(void)
  20 {
  21     i2c_bus *bus;
  22
  23     bus = (i2c_bus *)qemu_mallocz(sizeof(i2c_bus));
  24     return bus;
  25 }
  26
  27 /* Create a new slave device.  */
  28 i2c_slave *i2c_slave_init(i2c_bus *bus, int address, int size)
  29 {
  30     i2c_slave *dev;
  31
  32     if (size < sizeof(i2c_slave))
  33         cpu_abort(cpu_single_env, "I2C struct too small");
  34
  35     dev = (i2c_slave *)qemu_mallocz(size);
  36     dev->address = address;
  37     dev->next = bus->dev;
  38     bus->dev = dev;
  39
  40     return dev;
  41 }
  42
  43 void i2c_set_slave_address(i2c_slave *dev, int address)
  44 {
  45     dev->address = address;
  46 }
  47
  48 /* Return nonzero if bus is busy.  */
  49 int i2c_bus_busy(i2c_bus *bus)
  50 {
  51     return bus->current_dev != NULL;
  52 }
  53
  54 /* Returns non-zero if the address is not valid.  */
  55 /* TODO: Make this handle multiple masters.  */
  56 int i2c_start_transfer(i2c_bus *bus, int address, int recv)
  57 {
  58     i2c_slave *dev;
  59
  60     for (dev = bus->dev; dev; dev = dev->next) {
  61         if (dev->address == address)
  62             break;
  63     }
  64
  65     if (!dev)
  66         return 1;
  67
  68     /* If the bus is already busy, assume this is a repeated
  69        start condition.  */
  70     bus->current_dev = dev;
  71     dev->event(dev, recv ? I2C_START_RECV : I2C_START_SEND);
  72     return 0;
  73 }
  74
  75 void i2c_end_transfer(i2c_bus *bus)
  76 {
  77     i2c_slave *dev = bus->current_dev;
  78
  79     if (!dev)
  80         return;
  81
  82     dev->event(dev, I2C_FINISH);
  83
  84     bus->current_dev = NULL;
  85 }
  86
  87 int i2c_send(i2c_bus *bus, uint8_t data)
  88 {
  89     i2c_slave *dev = bus->current_dev;
  90
  91     if (!dev)
  92         return -1;
  93
  94     return dev->send(dev, data);
  95 }
  96
  97 int i2c_recv(i2c_bus *bus)
  98 {
  99     i2c_slave *dev = bus->current_dev;
 100
 101     if (!dev)
 102         return -1;
 103
 104     return dev->recv(dev);
 105 }
 106
 107 void i2c_nack(i2c_bus *bus)
 108 {
 109     i2c_slave *dev = bus->current_dev;
 110
 111     if (!dev)
 112         return;
 113
 114     dev->event(dev, I2C_NACK);
 115 }
 116
 117 void i2c_bus_save(QEMUFile *f, i2c_bus *bus)
 118 {
 119     qemu_put_byte(f, bus->current_dev ? bus->current_dev->address : 0x00);
 120 }
 121
 122 void i2c_bus_load(QEMUFile *f, i2c_bus *bus)
 123 {
 124     i2c_slave *dev;
 125     uint8_t address = qemu_get_byte(f);
 126
 127     if (address) {
 128         for (dev = bus->dev; dev; dev = dev->next)
 129             if (dev->address == address) {
 130                 bus->current_dev = dev;
 131                 return;
 132             }
 133
 134         fprintf(stderr, "%s: I2C slave with address %02x disappeared\n",
 135                 __FUNCTION__, address);
 136     }
 137 }
 138
 139 void i2c_slave_save(QEMUFile *f, i2c_slave *dev)
 140 {
 141     qemu_put_byte(f, dev->address);
 142 }
 143
 144 void i2c_slave_load(QEMUFile *f, i2c_slave *dev)
 145 {
 146     dev->address = qemu_get_byte(f);
 147 }