Shorter paths to HAL, ExtUI (#17156)

Marlin/src/HAL/LINUX/hardware/Clock.cpp

@@ -0,0 +1,32 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program 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 program 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/>.
+ *
+ */
+
+#ifdef __PLAT_LINUX__
+
+#include "../../../inc/MarlinConfig.h"
+#include "Clock.h"
+
+std::chrono::nanoseconds Clock::startup = std::chrono::high_resolution_clock::now().time_since_epoch();
+uint32_t Clock::frequency = F_CPU;
+double Clock::time_multiplier = 1.0;
+
+#endif // __PLAT_LINUX__

Marlin/src/HAL/LINUX/hardware/Clock.h

@@ -0,0 +1,89 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program 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 program 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/>.
+ *
+ */
+#pragma once
+
+#include <chrono>
+#include <thread>
+
+class Clock {
+public:
+  static uint64_t ticks(uint32_t frequency = Clock::frequency) {
+    return (Clock::nanos() - Clock::startup.count()) / (1000000000ULL / frequency);
+  }
+
+  static uint64_t nanosToTicks(uint64_t ns, uint32_t frequency = Clock::frequency) {
+    return ns / (1000000000ULL / frequency);
+  }
+
+  // Time acceleration compensated
+  static uint64_t ticksToNanos(uint64_t tick, uint32_t frequency = Clock::frequency) {
+    return (tick * (1000000000ULL / frequency)) / Clock::time_multiplier;
+  }
+
+  static void setFrequency(uint32_t freq) {
+    Clock::frequency = freq;
+  }
+
+  // Time Acceleration compensated
+  static uint64_t nanos() {
+    auto now = std::chrono::high_resolution_clock::now().time_since_epoch();
+    return (now.count() - Clock::startup.count()) * Clock::time_multiplier;
+  }
+
+  static uint64_t micros() {
+    return Clock::nanos() / 1000;
+  }
+
+  static uint64_t millis() {
+    return Clock::micros() / 1000;
+  }
+
+  static double seconds() {
+    return Clock::nanos() / 1000000000.0;
+  }
+
+  static void delayCycles(uint64_t cycles) {
+    std::this_thread::sleep_for(std::chrono::nanoseconds( (1000000000L / frequency) * cycles) / Clock::time_multiplier );
+  }
+
+  static void delayMicros(uint64_t micros) {
+    std::this_thread::sleep_for(std::chrono::microseconds( micros ) / Clock::time_multiplier);
+  }
+
+  static void delayMillis(uint64_t millis) {
+    std::this_thread::sleep_for(std::chrono::milliseconds( millis ) / Clock::time_multiplier);
+  }
+
+  static void delaySeconds(double secs) {
+    std::this_thread::sleep_for(std::chrono::duration<double, std::milli>(secs * 1000) / Clock::time_multiplier);
+  }
+
+  // Will reduce timer resolution increasing likelihood of overflows
+  static void setTimeMultiplier(double tm) {
+    Clock::time_multiplier = tm;
+  }
+
+private:
+  static std::chrono::nanoseconds startup;
+  static uint32_t frequency;
+  static double time_multiplier;
+};

Marlin/src/HAL/LINUX/hardware/Gpio.cpp

@@ -0,0 +1,30 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program 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 program 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/>.
+ *
+ */
+
+#ifdef __PLAT_LINUX__
+
+#include "Gpio.h"
+
+pin_data Gpio::pin_map[Gpio::pin_count+1] = {};
+IOLogger* Gpio::logger = nullptr;
+
+#endif // __PLAT_LINUX__

Marlin/src/HAL/LINUX/hardware/Gpio.h

@@ -0,0 +1,141 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program 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 program 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/>.
+ *
+ */
+#pragma once
+
+#include "Clock.h"
+#include "../../../inc/MarlinConfigPre.h"
+#include <stdint.h>
+
+typedef int16_t pin_type;
+
+struct GpioEvent {
+  enum Type {
+    NOP,
+    FALL,
+    RISE,
+    SET_VALUE,
+    SETM,
+    SETD
+  };
+  uint64_t timestamp;
+  pin_type pin_id;
+  GpioEvent::Type event;
+
+  GpioEvent(uint64_t timestamp, pin_type pin_id, GpioEvent::Type event){
+    this->timestamp = timestamp;
+    this->pin_id = pin_id;
+    this->event = event;
+  }
+};
+
+class IOLogger {
+public:
+  virtual ~IOLogger(){};
+  virtual void log(GpioEvent ev) = 0;
+};
+
+class Peripheral {
+public:
+  virtual ~Peripheral(){};
+  virtual void interrupt(GpioEvent ev) = 0;
+  virtual void update() = 0;
+};
+
+struct pin_data {
+  uint8_t dir;
+  uint8_t mode;
+  uint16_t value;
+  Peripheral* cb;
+};
+
+class Gpio {
+public:
+
+  static const pin_type pin_count = 255;
+  static pin_data pin_map[pin_count+1];
+
+  static bool valid_pin(pin_type pin) {
+    return pin >= 0 && pin <= pin_count;
+  }
+
+  static void set(pin_type pin) {
+    set(pin, 1);
+  }
+
+  static void set(pin_type pin, uint16_t value) {
+    if (!valid_pin(pin)) return;
+    GpioEvent::Type evt_type = value > 1 ? GpioEvent::SET_VALUE : value > pin_map[pin].value ? GpioEvent::RISE : value < pin_map[pin].value ? GpioEvent::FALL : GpioEvent::NOP;
+    pin_map[pin].value = value;
+    GpioEvent evt(Clock::nanos(), pin, evt_type);
+    if (pin_map[pin].cb != nullptr) {
+      pin_map[pin].cb->interrupt(evt);
+    }
+    if (Gpio::logger != nullptr) Gpio::logger->log(evt);
+  }
+
+  static uint16_t get(pin_type pin) {
+    if (!valid_pin(pin)) return 0;
+    return pin_map[pin].value;
+  }
+
+  static void clear(pin_type pin) {
+    set(pin, 0);
+  }
+
+  static void setMode(pin_type pin, uint8_t value) {
+    if (!valid_pin(pin)) return;
+    pin_map[pin].mode = value;
+    GpioEvent evt(Clock::nanos(), pin, GpioEvent::Type::SETM);
+    if (pin_map[pin].cb != nullptr) pin_map[pin].cb->interrupt(evt);
+    if (Gpio::logger != nullptr) Gpio::logger->log(evt);
+  }
+
+  static uint8_t getMode(pin_type pin) {
+    if (!valid_pin(pin)) return 0;
+    return pin_map[pin].mode;
+  }
+
+  static void setDir(pin_type pin, uint8_t value) {
+    if (!valid_pin(pin)) return;
+    pin_map[pin].dir = value;
+    GpioEvent evt(Clock::nanos(), pin, GpioEvent::Type::SETD);
+    if (pin_map[pin].cb != nullptr) pin_map[pin].cb->interrupt(evt);
+    if (Gpio::logger != nullptr) Gpio::logger->log(evt);
+  }
+
+  static uint8_t getDir(pin_type pin) {
+    if (!valid_pin(pin)) return 0;
+    return pin_map[pin].dir;
+  }
+
+  static void attachPeripheral(pin_type pin, Peripheral* per) {
+    if (!valid_pin(pin)) return;
+    pin_map[pin].cb = per;
+  }
+
+  static void attachLogger(IOLogger* logger) {
+    Gpio::logger = logger;
+  }
+
+private:
+  static IOLogger* logger;
+};

Marlin/src/HAL/LINUX/hardware/Heater.cpp

@@ -0,0 +1,61 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program 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 program 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/>.
+ *
+ */
+
+#ifdef __PLAT_LINUX__
+
+#include "Clock.h"
+#include <stdio.h>
+#include "../../../inc/MarlinConfig.h"
+
+#include "Heater.h"
+
+Heater::Heater(pin_t heater, pin_t adc) {
+  heater_state = 0;
+  room_temp_raw = 150;
+  last = Clock::micros();
+  heater_pin = heater;
+  adc_pin = adc;
+  heat = 0.0;
+}
+
+Heater::~Heater() {
+}
+
+void Heater::update() {
+  // crude pwm read and cruder heat simulation
+  auto now = Clock::micros();
+  double delta = (now - last);
+  if (delta > 1000 ) {
+    heater_state = pwmcap.update(0xFFFF * Gpio::pin_map[heater_pin].value);
+    last = now;
+    heat += (heater_state - heat) * (delta / 1000000000.0);
+
+    NOLESS(heat, room_temp_raw);
+    Gpio::pin_map[analogInputToDigitalPin(adc_pin)].value = 0xFFFF - (uint16_t)heat;
+  }
+}
+
+void Heater::interrupt(GpioEvent ev) {
+  // ununsed
+}
+
+#endif // __PLAT_LINUX__

Marlin/src/HAL/LINUX/hardware/Heater.h

@@ -0,0 +1,47 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program 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 program 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/>.
+ *
+ */
+#pragma once
+
+#include "Gpio.h"
+
+struct LowpassFilter {
+  uint64_t data_delay = 0;
+  uint16_t update(uint16_t value) {
+    data_delay = data_delay - (data_delay >> 6) + value;
+    return (uint16_t)(data_delay >> 6);
+  }
+};
+
+class Heater: public Peripheral {
+public:
+  Heater(pin_t heater, pin_t adc);
+  virtual ~Heater();
+  void interrupt(GpioEvent ev);
+  void update();
+
+  pin_t heater_pin, adc_pin;
+  uint16_t room_temp_raw;
+  uint16_t heater_state;
+  LowpassFilter pwmcap;
+  double heat;
+  uint64_t last;
+};

Marlin/src/HAL/LINUX/hardware/IOLoggerCSV.cpp

@@ -0,0 +1,50 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program 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 program 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/>.
+ *
+ */
+
+#ifdef __PLAT_LINUX__
+
+#include "IOLoggerCSV.h"
+
+IOLoggerCSV::IOLoggerCSV(std::string filename) {
+  file.open(filename);
+}
+
+IOLoggerCSV::~IOLoggerCSV() {
+  file.close();
+}
+
+void IOLoggerCSV::log(GpioEvent ev) {
+  std::lock_guard<std::mutex> lock(vector_lock);
+  events.push_back(ev); //minimal impact to signal handler
+}
+
+void IOLoggerCSV::flush() {
+  { std::lock_guard<std::mutex> lock(vector_lock);
+    while (!events.empty()) {
+      file << events.front().timestamp << ", "<< events.front().pin_id << ", " << events.front().event << std::endl;
+      events.pop_front();
+    }
+  }
+  file.flush();
+}
+
+#endif // __PLAT_LINUX__

Marlin/src/HAL/LINUX/hardware/IOLoggerCSV.h

@@ -0,0 +1,40 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program 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 program 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/>.
+ *
+ */
+#pragma once
+
+#include <mutex>
+#include <list>
+#include <fstream>
+#include "Gpio.h"
+
+class IOLoggerCSV: public IOLogger {
+public:
+  IOLoggerCSV(std::string filename);
+  virtual ~IOLoggerCSV();
+  void flush();
+  void log(GpioEvent ev);
+
+private:
+  std::ofstream file;
+  std::list<GpioEvent> events;
+  std::mutex vector_lock;
+};

Marlin/src/HAL/LINUX/hardware/LinearAxis.cpp

@@ -0,0 +1,66 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program 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 program 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/>.
+ *
+ */
+
+#ifdef __PLAT_LINUX__
+
+#include <random>
+#include <stdio.h>
+#include "Clock.h"
+#include "LinearAxis.h"
+
+LinearAxis::LinearAxis(pin_type enable, pin_type dir, pin_type step, pin_type end_min, pin_type end_max) {
+  enable_pin = enable;
+  dir_pin = dir;
+  step_pin = step;
+  min_pin = end_min;
+  max_pin = end_max;
+
+  min_position = 50;
+  max_position = (200*80) + min_position;
+  position = rand() % ((max_position - 40) - min_position) + (min_position + 20);
+  last_update = Clock::nanos();
+
+  Gpio::attachPeripheral(step_pin, this);
+
+}
+
+LinearAxis::~LinearAxis() {
+
+}
+
+void LinearAxis::update() {
+
+}
+
+void LinearAxis::interrupt(GpioEvent ev) {
+  if (ev.pin_id == step_pin && !Gpio::pin_map[enable_pin].value){
+    if (ev.event == GpioEvent::RISE) {
+      last_update = ev.timestamp;
+      position += -1 + 2 * Gpio::pin_map[dir_pin].value;
+      Gpio::pin_map[min_pin].value = (position < min_position);
+      //Gpio::pin_map[max_pin].value = (position > max_position);
+      //if (position < min_position) printf("axis(%d) endstop : pos: %d, mm: %f, min: %d\n", step_pin, position, position / 80.0, Gpio::pin_map[min_pin].value);
+    }
+  }
+}
+
+#endif // __PLAT_LINUX__

Marlin/src/HAL/LINUX/hardware/LinearAxis.h

@@ -0,0 +1,45 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program 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 program 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/>.
+ *
+ */
+#pragma once
+
+#include <chrono>
+#include "Gpio.h"
+
+class LinearAxis: public Peripheral {
+public:
+  LinearAxis(pin_type enable, pin_type dir, pin_type step, pin_type end_min, pin_type end_max);
+  virtual ~LinearAxis();
+  void update();
+  void interrupt(GpioEvent ev);
+
+  pin_type enable_pin;
+  pin_type dir_pin;
+  pin_type step_pin;
+  pin_type min_pin;
+  pin_type max_pin;
+
+  int32_t position;
+  int32_t min_position;
+  int32_t max_position;
+  uint64_t last_update;
+
+};

Marlin/src/HAL/LINUX/hardware/Timer.cpp

@@ -0,0 +1,118 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program 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 program 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/>.
+ *
+ */
+
+#ifdef __PLAT_LINUX__
+
+#include "Timer.h"
+#include <stdio.h>
+
+Timer::Timer() {
+  active = false;
+  compare = 0;
+  frequency = 0;
+  overruns = 0;
+  timerid = 0;
+  cbfn = nullptr;
+  period = 0;
+  start_time = 0;
+  avg_error = 0;
+}
+
+Timer::~Timer() {
+  timer_delete(timerid);
+}
+
+void Timer::init(uint32_t sig_id, uint32_t sim_freq, callback_fn* fn) {
+  struct sigaction sa;
+  struct sigevent sev;
+
+  frequency = sim_freq;
+  cbfn = fn;
+
+  sa.sa_flags = SA_SIGINFO;
+  sa.sa_sigaction = Timer::handler;
+  sigemptyset(&sa.sa_mask);
+  if (sigaction(SIGRTMIN, &sa, nullptr) == -1) {
+    return; // todo: handle error
+  }
+
+  sigemptyset(&mask);
+  sigaddset(&mask, SIGRTMIN);
+
+  disable();
+
+  sev.sigev_notify = SIGEV_SIGNAL;
+  sev.sigev_signo = SIGRTMIN;
+  sev.sigev_value.sival_ptr = (void*)this;
+  if (timer_create(CLOCK_REALTIME, &sev, &timerid) == -1) {
+    return; // todo: handle error
+  }
+}
+
+void Timer::start(uint32_t frequency) {
+  setCompare(this->frequency / frequency);
+  //printf("timer(%ld) started\n", getID());
+}
+
+void Timer::enable() {
+  if (sigprocmask(SIG_UNBLOCK, &mask, nullptr) == -1) {
+    return; // todo: handle error
+  }
+  active = true;
+  //printf("timer(%ld) enabled\n", getID());
+}
+
+void Timer::disable() {
+  if (sigprocmask(SIG_SETMASK, &mask, nullptr) == -1) {
+    return; // todo: handle error
+  }
+  active = false;
+}
+
+void Timer::setCompare(uint32_t compare) {
+  uint32_t nsec_offset = 0;
+  if (active) {
+    nsec_offset = Clock::nanos() - this->start_time; // calculate how long the timer would have been running for
+    nsec_offset = nsec_offset < 1000 ? nsec_offset : 0; // constrain, this shouldn't be needed but apparently Marlin enables interrupts on the stepper timer before initialising it, todo: investigate ?bug?
+  }
+  this->compare = compare;
+  uint64_t ns = Clock::ticksToNanos(compare, frequency) - nsec_offset;
+  struct itimerspec its;
+  its.it_value.tv_sec = ns / 1000000000;
+  its.it_value.tv_nsec = ns % 1000000000;
+  its.it_interval.tv_sec = its.it_value.tv_sec;
+  its.it_interval.tv_nsec = its.it_value.tv_nsec;
+
+  if (timer_settime(timerid, 0, &its, nullptr) == -1) {
+    printf("timer(%ld) failed, compare: %d(%ld)\n", getID(), compare, its.it_value.tv_nsec);
+    return; // todo: handle error
+  }
+  //printf("timer(%ld) started, compare: %d(%d)\n", getID(), compare, its.it_value.tv_nsec);
+  this->period = its.it_value.tv_nsec;
+  this->start_time = Clock::nanos();
+}
+
+uint32_t Timer::getCount() {
+  return Clock::nanosToTicks(Clock::nanos() - this->start_time, frequency);
+}
+
+#endif // __PLAT_LINUX__

Marlin/src/HAL/LINUX/hardware/Timer.h

@@ -0,0 +1,76 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program 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 program 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/>.
+ *
+ */
+#pragma once
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <signal.h>
+#include <time.h>
+#include <stdio.h>
+
+#include "Clock.h"
+
+class Timer {
+public:
+  Timer();
+  virtual ~Timer();
+
+  typedef void (callback_fn)();
+
+  void init(uint32_t sig_id, uint32_t sim_freq, callback_fn* fn);
+  void start(uint32_t frequency);
+  void enable();
+  bool enabled() {return active;}
+  void disable();
+  void setCompare(uint32_t compare);
+  uint32_t getCount();
+  uint32_t getCompare() {return compare;}
+  uint32_t getOverruns() {return overruns;}
+  uint32_t getAvgError() {return avg_error;}
+
+  intptr_t getID() {
+    return (*(intptr_t*)timerid);
+  }
+
+  static void handler(int sig, siginfo_t *si, void *uc){
+    Timer* _this = (Timer*)si->si_value.sival_ptr;
+    _this->avg_error += (Clock::nanos() - _this->start_time) - _this->period; //high_resolution_clock is also limited in precision, but best we have
+    _this->avg_error /= 2; //very crude precision analysis (actually within +-500ns usually)
+    _this->start_time = Clock::nanos(); // wrap
+    _this->cbfn();
+    _this->overruns += timer_getoverrun(_this->timerid); // even at 50Khz this doesn't stay zero, again demonstrating the limitations
+                                                         // using a realtime linux kernel would help somewhat
+  }
+
+private:
+  bool active;
+  uint32_t compare;
+  uint32_t frequency;
+  uint32_t overruns;
+  timer_t timerid;
+  sigset_t mask;
+  callback_fn* cbfn;
+  uint64_t period;
+  uint64_t avg_error;
+  uint64_t start_time;
+};