hw/misc/i2c-echo.c

   1 #include "qemu/osdep.h"
   2 #include "qemu/timer.h"
   3 #include "qemu/main-loop.h"
   4 #include "block/aio.h"
   5 #include "hw/i2c/i2c.h"
   6
   7 #define TYPE_I2C_ECHO "i2c-echo"
   8 OBJECT_DECLARE_SIMPLE_TYPE(I2CEchoState, I2C_ECHO)
   9
  10 enum i2c_echo_state {
  11     I2C_ECHO_STATE_IDLE,
  12     I2C_ECHO_STATE_START_SEND,
  13     I2C_ECHO_STATE_ACK,
  14 };
  15
  16 typedef struct I2CEchoState {
  17     I2CSlave parent_obj;
  18
  19     I2CBus *bus;
  20
  21     enum i2c_echo_state state;
  22     QEMUBH *bh;
  23
  24     unsigned int pos;
  25     uint8_t data[3];
  26 } I2CEchoState;
  27
  28 static void i2c_echo_bh(void *opaque)
  29 {
  30     I2CEchoState *state = opaque;
  31
  32     switch (state->state) {
  33     case I2C_ECHO_STATE_IDLE:
  34         return;
  35
  36     case I2C_ECHO_STATE_START_SEND:
  37         if (i2c_start_send_async(state->bus, state->data[0])) {
  38             goto release_bus;
  39         }
  40
  41         state->pos++;
  42         state->state = I2C_ECHO_STATE_ACK;
  43         return;
  44
  45     case I2C_ECHO_STATE_ACK:
  46         if (state->pos > 2) {
  47             break;
  48         }
  49
  50         if (i2c_send_async(state->bus, state->data[state->pos++])) {
  51             break;
  52         }
  53
  54         return;
  55     }
  56
  57
  58     i2c_end_transfer(state->bus);
  59 release_bus:
  60     i2c_bus_release(state->bus);
  61
  62     state->state = I2C_ECHO_STATE_IDLE;
  63 }
  64
  65 static int i2c_echo_event(I2CSlave *s, enum i2c_event event)
  66 {
  67     I2CEchoState *state = I2C_ECHO(s);
  68
  69     switch (event) {
  70     case I2C_START_RECV:
  71         state->pos = 0;
  72
  73         break;
  74
  75     case I2C_START_SEND:
  76         state->pos = 0;
  77
  78         break;
  79
  80     case I2C_FINISH:
  81         state->pos = 0;
  82         state->state = I2C_ECHO_STATE_START_SEND;
  83         i2c_bus_master(state->bus, state->bh);
  84
  85         break;
  86
  87     case I2C_NACK:
  88         break;
  89
  90     default:
  91         return -1;
  92     }
  93
  94     return 0;
  95 }
  96
  97 static uint8_t i2c_echo_recv(I2CSlave *s)
  98 {
  99     I2CEchoState *state = I2C_ECHO(s);
 100
 101     if (state->pos > 2) {
 102         return 0xff;
 103     }
 104
 105     return state->data[state->pos++];
 106 }
 107
 108 static int i2c_echo_send(I2CSlave *s, uint8_t data)
 109 {
 110     I2CEchoState *state = I2C_ECHO(s);
 111
 112     if (state->pos > 2) {
 113         return -1;
 114     }
 115
 116     state->data[state->pos++] = data;
 117
 118     return 0;
 119 }
 120
 121 static void i2c_echo_realize(DeviceState *dev, Error **errp)
 122 {
 123     I2CEchoState *state = I2C_ECHO(dev);
 124     BusState *bus = qdev_get_parent_bus(dev);
 125
 126     state->bus = I2C_BUS(bus);
 127     state->bh = qemu_bh_new(i2c_echo_bh, state);
 128
 129     return;
 130 }
 131
 132 static void i2c_echo_class_init(ObjectClass *oc, void *data)
 133 {
 134     I2CSlaveClass *sc = I2C_SLAVE_CLASS(oc);
 135     DeviceClass *dc = DEVICE_CLASS(oc);
 136
 137     dc->realize = i2c_echo_realize;
 138
 139     sc->event = i2c_echo_event;
 140     sc->recv = i2c_echo_recv;
 141     sc->send = i2c_echo_send;
 142 }
 143
 144 static const TypeInfo i2c_echo = {
 145     .name = TYPE_I2C_ECHO,
 146     .parent = TYPE_I2C_SLAVE,
 147     .instance_size = sizeof(I2CEchoState),
 148     .class_init = i2c_echo_class_init,
 149 };
 150
 151 static void register_types(void)
 152 {
 153     type_register_static(&i2c_echo);
 154 }
 155
 156 type_init(register_types);