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 "hw.h"

    11 #include "i2c.h"

    12 

    13 struct i2c_bus

    14 {

    15     i2c_slave *current_dev;

    16     i2c_slave *dev;

    17     int saved_address;

    18 };

    19 

    20 static void i2c_bus_save(QEMUFile *f, void *opaque)

    21 {

    22     i2c_bus *bus = (i2c_bus *)opaque;

    23 

    24     qemu_put_byte(f, bus->current_dev ? bus->current_dev->address : -1);

    25 }

    26 

    27 static int i2c_bus_load(QEMUFile *f, void *opaque, int version_id)

    28 {

    29     i2c_bus *bus = (i2c_bus *)opaque;

    30 

    31     if (version_id != 1)

    32         return -EINVAL;

    33 

    34     /* The bus is loaded before attached devices, so load and save the

    35        current device id.  Devices will check themselves as loaded.  */

    36     bus->saved_address = (int8_t) qemu_get_byte(f);

    37     bus->current_dev = NULL;

    38 

    39     return 0;

    40 }

    41 

    42 /* Create a new I2C bus.  */

    43 i2c_bus *i2c_init_bus(void)

    44 {

    45     i2c_bus *bus;

    46 

    47     bus = (i2c_bus *)qemu_mallocz(sizeof(i2c_bus));

    48     register_savevm("i2c_bus", -1, 1, i2c_bus_save, i2c_bus_load, bus);

    49     return bus;

    50 }

    51 

    52 /* Create a new slave device.  */

    53 i2c_slave *i2c_slave_init(i2c_bus *bus, int address, int size)

    54 {

    55     i2c_slave *dev;

    56 

    57     if (size < sizeof(i2c_slave))

    58         hw_error("I2C struct too small");

    59 

    60     dev = (i2c_slave *)qemu_mallocz(size);

    61     dev->address = address;

    62     dev->next = bus->dev;

    63     bus->dev = dev;

    64     dev->bus = bus;

    65 

    66     return dev;

    67 }

    68 

    69 void i2c_set_slave_address(i2c_slave *dev, int address)

    70 {

    71     dev->address = address;

    72 }

    73 

    74 /* Return nonzero if bus is busy.  */

    75 int i2c_bus_busy(i2c_bus *bus)

    76 {

    77     return bus->current_dev != NULL;

    78 }

    79 

    80 /* Returns non-zero if the address is not valid.  */

    81 /* TODO: Make this handle multiple masters.  */

    82 int i2c_start_transfer(i2c_bus *bus, int address, int recv)

    83 {

    84     i2c_slave *dev;

    85 

    86     for (dev = bus->dev; dev; dev = dev->next) {

    87         if (dev->address == address)

    88             break;

    89     }

    90 

    91     if (!dev)

    92         return 1;

    93 

    94     /* If the bus is already busy, assume this is a repeated

    95        start condition.  */

    96     bus->current_dev = dev;

    97     dev->event(dev, recv ? I2C_START_RECV : I2C_START_SEND);

    98     return 0;

    99 }

   100 

   101 void i2c_end_transfer(i2c_bus *bus)

   102 {

   103     i2c_slave *dev = bus->current_dev;

   104 

   105     if (!dev)

   106         return;

   107 

   108     dev->event(dev, I2C_FINISH);

   109 

   110     bus->current_dev = NULL;

   111 }

   112 

   113 int i2c_send(i2c_bus *bus, uint8_t data)

   114 {

   115     i2c_slave *dev = bus->current_dev;

   116 

   117     if (!dev)

   118         return -1;

   119 

   120     return dev->send(dev, data);

   121 }

   122 

   123 int i2c_recv(i2c_bus *bus)

   124 {

   125     i2c_slave *dev = bus->current_dev;

   126 

   127     if (!dev)

   128         return -1;

   129 

   130     return dev->recv(dev);

   131 }

   132 

   133 void i2c_nack(i2c_bus *bus)

   134 {

   135     i2c_slave *dev = bus->current_dev;

   136 

   137     if (!dev)

   138         return;

   139 

   140     dev->event(dev, I2C_NACK);

   141 }

   142 

   143 void i2c_slave_save(QEMUFile *f, i2c_slave *dev)

   144 {

   145     qemu_put_byte(f, dev->address);

   146 }

   147 

   148 void i2c_slave_load(QEMUFile *f, i2c_slave *dev)

   149 {

   150     dev->address = qemu_get_byte(f);

   151     if (dev->bus->saved_address == dev->address)

   152         dev->bus->current_dev = dev;

   153 }