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 nonzero if the bus is already busy, or is the address is not
  55    valid.  */
  56 /* TODO: Make this handle multiple masters.  */
  57 int i2c_start_transfer(i2c_bus *bus, int address, int recv)
  58 {
  59     i2c_slave *dev;
  60
  61     for (dev = bus->dev; dev; dev = dev->next) {
  62         if (dev->address == address)
  63             break;
  64     }
  65
  66     if (!dev)
  67         return 1;
  68
  69     /* If the bus is already busy, assume this is a repeated
  70        start condition.  */
  71     bus->current_dev = dev;
  72     dev->event(dev, recv ? I2C_START_RECV : I2C_START_SEND);
  73     return 0;
  74 }
  75
  76 void i2c_end_transfer(i2c_bus *bus)
  77 {
  78     i2c_slave *dev = bus->current_dev;
  79
  80     if (!dev)
  81         return;
  82
  83     dev->event(dev, I2C_FINISH);
  84
  85     bus->current_dev = NULL;
  86 }
  87
  88 int i2c_send(i2c_bus *bus, uint8_t data)
  89 {
  90     i2c_slave *dev = bus->current_dev;
  91
  92     if (!dev)
  93         return -1;
  94
  95     return dev->send(dev, data);
  96 }
  97
  98 int i2c_recv(i2c_bus *bus)
  99 {
 100     i2c_slave *dev = bus->current_dev;
 101
 102     if (!dev)
 103         return -1;
 104
 105     return dev->recv(dev);
 106 }
 107
 108 void i2c_nack(i2c_bus *bus)
 109 {
 110     i2c_slave *dev = bus->current_dev;
 111
 112     if (!dev)
 113         return;
 114
 115     dev->event(dev, I2C_NACK);
 116 }
 117
 118 void i2c_bus_save(QEMUFile *f, i2c_bus *bus)
 119 {
 120     qemu_put_byte(f, bus->current_dev ? bus->current_dev->address : 0x00);
 121 }
 122
 123 void i2c_bus_load(QEMUFile *f, i2c_bus *bus)
 124 {
 125     i2c_slave *dev;
 126     uint8_t address = qemu_get_byte(f);
 127
 128     if (address) {
 129         for (dev = bus->dev; dev; dev = dev->next)
 130             if (dev->address == address) {
 131                 bus->current_dev = dev;
 132                 return;
 133             }
 134
 135         fprintf(stderr, "%s: I2C slave with address %02x disappeared\n",
 136                 __FUNCTION__, address);
 137     }
 138 }
 139
 140 void i2c_slave_save(QEMUFile *f, i2c_slave *dev)
 141 {
 142     qemu_put_byte(f, dev->address);
 143 }
 144
 145 void i2c_slave_load(QEMUFile *f, i2c_slave *dev)
 146 {
 147     dev->address = qemu_get_byte(f);
 148 }