ardupilot/libraries/AP_HAL_ChibiOS/I2CDevice.cpp

/*
 * This file is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This file is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include "I2CDevice.h"

#include <AP_HAL/AP_HAL.h>
#include <AP_Math/AP_Math.h>
#include "Util.h"
#include "Scheduler.h"

#include "ch.h"
#include "hal.h"

static I2CDriver* I2CD[] = {
    &I2CD2,
    &I2CD1
};

static uint8_t tx_dma_stream[] = {
    STM32_I2C_I2C2_TX_DMA_STREAM,
    STM32_I2C_I2C1_TX_DMA_STREAM
};

static uint8_t rx_dma_stream[] = {
    STM32_I2C_I2C2_RX_DMA_STREAM,
    STM32_I2C_I2C1_RX_DMA_STREAM
};

using namespace ChibiOS;

I2CBus I2CDeviceManager::businfo[ARRAY_SIZE(I2CD)];

// get a handle for DMA sharing DMA channels with other subsystems
void I2CBus::dma_init(void)
{
    dma_handle = new Shared_DMA(tx_dma_stream[busnum], rx_dma_stream[busnum],
                                FUNCTOR_BIND_MEMBER(&I2CBus::dma_allocate, void),
                                FUNCTOR_BIND_MEMBER(&I2CBus::dma_deallocate, void));    
}

// setup I2C buses
I2CDeviceManager::I2CDeviceManager(void)
{
    for (uint8_t i=0; i<ARRAY_SIZE(I2CD); i++) {
        businfo[i].busnum = i;
        businfo[i].dma_init();
        /*
          setup default I2C config. As each device is opened we will
          drop the speed to be the minimum speed requested
         */
        businfo[i].i2ccfg.op_mode = OPMODE_I2C;
        businfo[i].i2ccfg.clock_speed = 400000;
        businfo[i].i2ccfg.duty_cycle = FAST_DUTY_CYCLE_2;
    }
}

I2CDevice::I2CDevice(uint8_t busnum, uint8_t address, uint32_t bus_clock, bool use_smbus, uint32_t timeout_ms) :
    _retries(2),
    _address(address),
    _use_smbus(use_smbus),
    _timeout_ms(timeout_ms),
    bus(I2CDeviceManager::businfo[busnum])
{
    set_device_bus(busnum);
    set_device_address(address);
    asprintf(&pname, "I2C:%u:%02x",
             (unsigned)busnum, (unsigned)address);
    if (bus_clock < bus.i2ccfg.clock_speed) {
        bus.i2ccfg.clock_speed = bus_clock;
        if (bus_clock <= 100000) {
            bus.i2ccfg.duty_cycle = STD_DUTY_CYCLE;
        }
    }
}

I2CDevice::~I2CDevice()
{
    printf("I2C device bus %u address 0x%02x closed\n", 
           (unsigned)bus.busnum, (unsigned)_address);
    free(pname);
}

/*
  allocate DMA channel
 */
void I2CBus::dma_allocate(void)
{
    i2cStart(I2CD[busnum], &i2ccfg);
}

/*
  deallocate DMA channel
 */
void I2CBus::dma_deallocate(void)
{
    i2cStop(I2CD[busnum]);
}

bool I2CDevice::transfer(const uint8_t *send, uint32_t send_len,
                         uint8_t *recv, uint32_t recv_len)
{
    bus.dma_handle->lock();

    if (_use_smbus) {
        bus.i2ccfg.op_mode = OPMODE_SMBUS_HOST;
    } else {
        bus.i2ccfg.op_mode = OPMODE_I2C;
    }
    
    if (_split_transfers) {
        /*
          splitting the transfer() into two pieces avoids a stop condition
          with SCL low which is not supported on some devices (such as
          LidarLite blue label)
        */
        if (send && send_len) {
            if (!_transfer(send, send_len, nullptr, 0)) {
                bus.dma_handle->unlock();
                return false;
            }
        }
        if (recv && recv_len) {
            if (!_transfer(nullptr, 0, recv, recv_len)) {
                bus.dma_handle->unlock();
                return false;
            }
        }
    } else {
        // combined transfer
        if (!_transfer(send, send_len, recv, recv_len)) {
            bus.dma_handle->unlock();
            return false;
        }
    }

    bus.dma_handle->unlock();
    return true;
}

bool I2CDevice::_transfer(const uint8_t *send, uint32_t send_len,
                         uint8_t *recv, uint32_t recv_len)
{
    int ret;
    for(uint8_t i=0 ; i <= _retries; i++) {
        i2cAcquireBus(I2CD[bus.busnum]);
        // calculate a timeout as twice the expected transfer time, and set as min of 4ms
        uint32_t timeout_ms = 1+2*(((8*1000000UL/bus.i2ccfg.clock_speed)*MAX(send_len, recv_len))/1000);
        timeout_ms = MAX(timeout_ms, _timeout_ms);
        if(send_len == 0) {
            ret = i2cMasterReceiveTimeout(I2CD[bus.busnum], _address,recv, recv_len, MS2ST(timeout_ms));
        } else {
            ret = i2cMasterTransmitTimeout(I2CD[bus.busnum], _address, send, send_len,
                                           recv, recv_len, MS2ST(timeout_ms));
        }
        i2cReleaseBus(I2CD[bus.busnum]);
        if (ret != MSG_OK){
            //restart the bus
            i2cStop(I2CD[bus.busnum]);
            i2cStart(I2CD[bus.busnum], &bus.i2ccfg);
        } else {
            return true;
        }
    }
    return false;
}

bool I2CDevice::read_registers_multiple(uint8_t first_reg, uint8_t *recv,
                                        uint32_t recv_len, uint8_t times)
{
    return false;
}

    
/*
  register a periodic callback
*/
AP_HAL::Device::PeriodicHandle I2CDevice::register_periodic_callback(uint32_t period_usec, AP_HAL::Device::PeriodicCb cb)
{
    return bus.register_periodic_callback(period_usec, cb, this);
}
    

/*
  adjust a periodic callback
*/
bool I2CDevice::adjust_periodic_callback(AP_HAL::Device::PeriodicHandle h, uint32_t period_usec)
{
    return bus.adjust_timer(h, period_usec);
}

AP_HAL::OwnPtr<AP_HAL::I2CDevice>
I2CDeviceManager::get_device(uint8_t bus, uint8_t address,
                             uint32_t bus_clock,
                             bool use_smbus,
                             uint32_t timeout_ms)
{
    if (bus >= ARRAY_SIZE(I2CD)) {
        return AP_HAL::OwnPtr<AP_HAL::I2CDevice>(nullptr);
    }
    auto dev = AP_HAL::OwnPtr<AP_HAL::I2CDevice>(new I2CDevice(bus, address, bus_clock, use_smbus, timeout_ms));
    return dev;
}