mirror of https://gitee.com/openkylin/qemu.git
149 lines
2.7 KiB
C
149 lines
2.7 KiB
C
/*
|
|
* QEMU I2C bus interface.
|
|
*
|
|
* Copyright (c) 2007 CodeSourcery.
|
|
* Written by Paul Brook
|
|
*
|
|
* This code is licenced under the LGPL.
|
|
*/
|
|
|
|
#include "vl.h"
|
|
|
|
struct i2c_bus
|
|
{
|
|
i2c_slave *current_dev;
|
|
i2c_slave *dev;
|
|
};
|
|
|
|
/* Create a new I2C bus. */
|
|
i2c_bus *i2c_init_bus(void)
|
|
{
|
|
i2c_bus *bus;
|
|
|
|
bus = (i2c_bus *)qemu_mallocz(sizeof(i2c_bus));
|
|
return bus;
|
|
}
|
|
|
|
/* Create a new slave device. */
|
|
i2c_slave *i2c_slave_init(i2c_bus *bus, int address, int size)
|
|
{
|
|
i2c_slave *dev;
|
|
|
|
if (size < sizeof(i2c_slave))
|
|
cpu_abort(cpu_single_env, "I2C struct too small");
|
|
|
|
dev = (i2c_slave *)qemu_mallocz(size);
|
|
dev->address = address;
|
|
dev->next = bus->dev;
|
|
bus->dev = dev;
|
|
|
|
return dev;
|
|
}
|
|
|
|
void i2c_set_slave_address(i2c_slave *dev, int address)
|
|
{
|
|
dev->address = address;
|
|
}
|
|
|
|
/* Return nonzero if bus is busy. */
|
|
int i2c_bus_busy(i2c_bus *bus)
|
|
{
|
|
return bus->current_dev != NULL;
|
|
}
|
|
|
|
/* Returns nonzero if the bus is already busy, or is the address is not
|
|
valid. */
|
|
/* TODO: Make this handle multiple masters. */
|
|
int i2c_start_transfer(i2c_bus *bus, int address, int recv)
|
|
{
|
|
i2c_slave *dev;
|
|
|
|
for (dev = bus->dev; dev; dev = dev->next) {
|
|
if (dev->address == address)
|
|
break;
|
|
}
|
|
|
|
if (!dev)
|
|
return 1;
|
|
|
|
/* If the bus is already busy, assume this is a repeated
|
|
start condition. */
|
|
bus->current_dev = dev;
|
|
dev->event(dev, recv ? I2C_START_RECV : I2C_START_SEND);
|
|
return 0;
|
|
}
|
|
|
|
void i2c_end_transfer(i2c_bus *bus)
|
|
{
|
|
i2c_slave *dev = bus->current_dev;
|
|
|
|
if (!dev)
|
|
return;
|
|
|
|
dev->event(dev, I2C_FINISH);
|
|
|
|
bus->current_dev = NULL;
|
|
}
|
|
|
|
int i2c_send(i2c_bus *bus, uint8_t data)
|
|
{
|
|
i2c_slave *dev = bus->current_dev;
|
|
|
|
if (!dev)
|
|
return -1;
|
|
|
|
return dev->send(dev, data);
|
|
}
|
|
|
|
int i2c_recv(i2c_bus *bus)
|
|
{
|
|
i2c_slave *dev = bus->current_dev;
|
|
|
|
if (!dev)
|
|
return -1;
|
|
|
|
return dev->recv(dev);
|
|
}
|
|
|
|
void i2c_nack(i2c_bus *bus)
|
|
{
|
|
i2c_slave *dev = bus->current_dev;
|
|
|
|
if (!dev)
|
|
return;
|
|
|
|
dev->event(dev, I2C_NACK);
|
|
}
|
|
|
|
void i2c_bus_save(QEMUFile *f, i2c_bus *bus)
|
|
{
|
|
qemu_put_byte(f, bus->current_dev ? bus->current_dev->address : 0x00);
|
|
}
|
|
|
|
void i2c_bus_load(QEMUFile *f, i2c_bus *bus)
|
|
{
|
|
i2c_slave *dev;
|
|
uint8_t address = qemu_get_byte(f);
|
|
|
|
if (address) {
|
|
for (dev = bus->dev; dev; dev = dev->next)
|
|
if (dev->address == address) {
|
|
bus->current_dev = dev;
|
|
return;
|
|
}
|
|
|
|
fprintf(stderr, "%s: I2C slave with address %02x disappeared\n",
|
|
__FUNCTION__, address);
|
|
}
|
|
}
|
|
|
|
void i2c_slave_save(QEMUFile *f, i2c_slave *dev)
|
|
{
|
|
qemu_put_byte(f, dev->address);
|
|
}
|
|
|
|
void i2c_slave_load(QEMUFile *f, i2c_slave *dev)
|
|
{
|
|
dev->address = qemu_get_byte(f);
|
|
}
|