ocpoc_mmap.cpp

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#include "ocpoc_mmap.h"

#include <px4_platform_common/log.h>

#include <fcntl.h>
#include <sys/mman.h>
#include <unistd.h>

using namespace linux_pwm_out;

#define RCOUT_ZYNQ_PWM_BASE     0x43c00000
static const int TICK_PER_US   =  50;
static const int FREQUENCY_PWM = 400;
static const int TICK_PER_S  = 50000000;

OcpocMmapPWMOut::OcpocMmapPWMOut(int max_num_outputs)
{
    _num_outputs = max_num_outputs;

    if (_num_outputs > MAX_ZYNQ_PWMS) {
        PX4_WARN("number of outputs too large. Setting to %i", MAX_ZYNQ_PWMS);
        _num_outputs = MAX_ZYNQ_PWMS;
    }
}

OcpocMmapPWMOut::~OcpocMmapPWMOut()
{
    if (_shared_mem_cmd) {
        munmap((void *)_shared_mem_cmd, 0x1000);
    }
}

unsigned long OcpocMmapPWMOut::freq2tick(uint16_t freq_hz)
{
    unsigned long duty = TICK_PER_S / (unsigned long)freq_hz;
    return duty;
}

int OcpocMmapPWMOut::init()
{
    uint32_t mem_fd = open(_device, O_RDWR | O_SYNC);
    _shared_mem_cmd = (struct pwm_cmd *) mmap(0, 0x1000, PROT_READ | PROT_WRITE,
              MAP_SHARED, mem_fd, RCOUT_ZYNQ_PWM_BASE);
    close(mem_fd);

    if (_shared_mem_cmd == nullptr) {
        PX4_ERR("initialize pwm pointer failed.");
        return -1;
    }

    for (int i = 0; i < _num_outputs; ++i) {
        _shared_mem_cmd->periodhi[i].period   =  freq2tick(FREQUENCY_PWM);
        _shared_mem_cmd->periodhi[i].hi = freq2tick(FREQUENCY_PWM) / 2;
        PX4_DEBUG("Output values: %d, %d", _shared_mem_cmd->periodhi[i].period, _shared_mem_cmd->periodhi[i].hi);
    }

    return 0;
}

int OcpocMmapPWMOut::send_output_pwm(const uint16_t *pwm, int num_outputs)
{
    if (num_outputs > _num_outputs) {
        num_outputs = _num_outputs;
    }

    //convert this to duty_cycle in ns
    for (int i = 0; i < num_outputs; ++i) {
        //n = ::asprintf(&data, "%u", pwm[i] * 1000);
        //::write(_pwm_fd[i], data, n);
        _shared_mem_cmd->periodhi[i].hi = TICK_PER_US * pwm[i];
        //printf("ch:%d, val:%d*%d ", ch, period_us, TICK_PER_US);
    }

    return 0;
}