text: /* Copyright 2018 Espressif Systems (Shanghai) PTE LTD
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  /*
   * FreeModbus Libary: ESP32 Port Demo Application
   * Copyright (C) 2010 Christian Walter <cwalter@embedded-solutions.at>
   *
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *   notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *   notice, this list of conditions and the following disclaimer in the
   *   documentation and/or other materials provided with the distribution.
   * 3. The name of the author may not be used to endorse or promote products
   *   derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * IF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   * File: $Id: portother.c,v 1.1 2010/06/06 13:07:20 wolti Exp $
   */
  /* ----------------------- Platform includes --------------------------------*/
  #include "port.h"
  
  /* ----------------------- Modbus includes ----------------------------------*/
  #include "sdkconfig.h"
  #include "mb.h"
  #include "mbport.h"
  #include "driver/timer.h"
  #include "port_serial_slave.h"
  #include "sdkconfig.h"
  
  #if CONFIG_FMB_TIMER_PORT_ENABLED
  
  #define MB_US50_FREQ            (20000) // 20kHz 1/20000 = 50mks
  #define MB_DISCR_TIME_US        (50)    // 50uS = one discreet for timer
  
  #define MB_TIMER_PRESCALLER     ((TIMER_BASE_CLK / MB_US50_FREQ) - 1);
  #define MB_TIMER_SCALE          (TIMER_BASE_CLK / TIMER_DIVIDER)  // convert counter value to seconds
  #define MB_TIMER_DIVIDER        ((TIMER_BASE_CLK / 1000000UL) * MB_DISCR_TIME_US - 1) // divider for 50uS
  #define MB_TIMER_WITH_RELOAD    (1)
  
  static const USHORT usTimerIndex = CONFIG_FMB_TIMER_INDEX;      // Modbus Timer index used by stack
  static const USHORT usTimerGroupIndex = CONFIG_FMB_TIMER_GROUP; // Modbus Timer group index used by stack
  static timer_isr_handle_t xTimerIntHandle;                      // Timer interrupt handle
  
  /* ----------------------- Start implementation -----------------------------*/
  static void IRAM_ATTR vTimerGroupIsr(void *param)
  {
      assert((int)param == usTimerIndex);
      // Retrieve the counter value from the timer that reported the interrupt
      timer_group_clr_intr_status_in_isr(usTimerGroupIndex, usTimerIndex);
      (void)pxMBPortCBTimerExpired(); // Timer callback function
      // Enable alarm
      timer_group_enable_alarm_in_isr(usTimerGroupIndex, usTimerIndex);
  }
  #endif
  
  BOOL xMBPortTimersInit(USHORT usTim1Timerout50us)
  {
  #if CONFIG_FMB_TIMER_PORT_ENABLED
      MB_PORT_CHECK((usTim1Timerout50us > 0), FALSE,
              "Modbus timeout discreet is incorrect.");
      esp_err_t xErr;
      timer_config_t config;
      config.alarm_en = TIMER_ALARM_EN;
      config.auto_reload = MB_TIMER_WITH_RELOAD;
      config.counter_dir = TIMER_COUNT_UP;
      config.divider = MB_TIMER_PRESCALLER;
      config.intr_type = TIMER_INTR_LEVEL;
      config.counter_en = TIMER_PAUSE;
      // Configure timer
      xErr = timer_init(usTimerGroupIndex, usTimerIndex, &config);
      MB_PORT_CHECK((xErr == ESP_OK), FALSE,
              "timer init failure, timer_init() returned (0x%x).", xErr);
      // Stop timer counter
      xErr = timer_pause(usTimerGroupIndex, usTimerIndex);
      MB_PORT_CHECK((xErr == ESP_OK), FALSE,
                      "stop timer failure, timer_pause() returned (0x%x).", xErr);
      // Reset counter value
      xErr = timer_set_counter_value(usTimerGroupIndex, usTimerIndex, 0x00000000ULL);
      MB_PORT_CHECK((xErr == ESP_OK), FALSE,
                      "timer set value failure, timer_set_counter_value() returned (0x%x).", xErr);
      // wait3T5_us = 35 * 11 * 100000 / baud; // the 3.5T symbol time for baudrate
      // Set alarm value for usTim1Timerout50us * 50uS
      xErr = timer_set_alarm_value(usTimerGroupIndex, usTimerIndex, (uint32_t)(usTim1Timerout50us));
      MB_PORT_CHECK((xErr == ESP_OK), FALSE,
                      "failure to set alarm failure, timer_set_alarm_value() returned (0x%x).",
                      (uint32_t)xErr);
      // Register ISR for timer
      xErr = timer_isr_register(usTimerGroupIndex, usTimerIndex, vTimerGroupIsr,
                                  (void*)(uint32_t)usTimerIndex, MB_PORT_TIMER_ISR_FLAG, &xTimerIntHandle);
      MB_PORT_CHECK((xErr == ESP_OK), FALSE,
                      "timer set value failure, timer_isr_register() returned (0x%x).",
                      (uint32_t)xErr);
  #endif
      return TRUE;
  }
  
  void vMBPortTimersEnable(void)
  {
  #if CONFIG_FMB_TIMER_PORT_ENABLED
      ESP_ERROR_CHECK(timer_pause(usTimerGroupIndex, usTimerIndex));
      ESP_ERROR_CHECK(timer_set_counter_value(usTimerGroupIndex, usTimerIndex, 0ULL));
      ESP_ERROR_CHECK(timer_enable_intr(usTimerGroupIndex, usTimerIndex));
      ESP_ERROR_CHECK(timer_start(usTimerGroupIndex, usTimerIndex));
  #endif
  }
  
  void MB_PORT_ISR_ATTR
  vMBPortTimersDisable(void)
  {
  #if CONFIG_FMB_TIMER_PORT_ENABLED
      if( (BOOL)xPortInIsrContext() ) {
          timer_group_set_counter_enable_in_isr(usTimerGroupIndex, usTimerIndex, TIMER_PAUSE);
      } else {
          ESP_ERROR_CHECK(timer_pause(usTimerGroupIndex, usTimerIndex));
          ESP_ERROR_CHECK(timer_set_counter_value(usTimerGroupIndex, usTimerIndex, 0ULL));
          // Disable timer interrupt
          ESP_ERROR_CHECK(timer_disable_intr(usTimerGroupIndex, usTimerIndex));
      }
  #endif
  }
  
  void vMBPortTimerClose(void)
  {
  #ifdef CONFIG_FMB_TIMER_PORT_ENABLED
      ESP_ERROR_CHECK(timer_pause(usTimerGroupIndex, usTimerIndex));
      ESP_ERROR_CHECK(timer_disable_intr(usTimerGroupIndex, usTimerIndex));
      ESP_ERROR_CHECK(esp_intr_free(xTimerIntHandle));
  #endif
  }
  