text: /****************************************************************************
   * arch/arm/src/stm32/stm32l4_exti_comp.c
   *
   *   Copyright (c) 2017 Gregory Nutt. All rights reserved
   *   Copyright (c) 2016 Motorola Mobility, LLC. All rights reserved.
   *
   * 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. Neither the name NuttX nor the names of its contributors may be
   *    used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   * COPYRIGHT OWNER OR CONTRIBUTORS 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.
   *
   ****************************************************************************/
  
  /****************************************************************************
   * Included Files
   ****************************************************************************/
  
  #include <nuttx/config.h>
  
  #include <nuttx/irq.h>
  #include <nuttx/arch.h>
  
  #include "up_arch.h"
  #include "stm32l4_comp.h"
  #include "stm32l4_exti.h"
  #include "chip/stm32l4_exti.h"
  
  /****************************************************************************
   * Private Types
   ****************************************************************************/
  
  struct comp_callback_s
  {
    xcpt_t callback;
    void  *arg;
  };
  
  /****************************************************************************
   * Private Data
   ****************************************************************************/
  
  /* Interrupt handlers attached to the COMP EXTI lines */
  
  static struct comp_callback_s g_comp_handlers[STM32L4_COMP_NUM];
  
  /* Comparator EXTI lines */
  
  static const uint32_t g_comp_lines[STM32L4_COMP_NUM] =
  {
  #if defined(CONFIG_STM32L4_STM32L4X2) || defined(CONFIG_STM32L4_STM32L4X3) || \
      defined(CONFIG_STM32L4_STM32L4X5) || defined(CONFIG_STM32L4_STM32L4X6)
    EXTI1_COMP1,
    EXTI1_COMP2
  #else
  #  error "Unrecognized STM32L4 chip"
  #endif
  };
  
   /****************************************************************************
   * Private Functions
   ****************************************************************************/
  
  static int stm32l4_exti_comp_isr(int irq, void *context, FAR void *arg)
  {
    uint32_t pr;
    uint32_t ln;
    int ret = 0;
    int i;
  
    /* Examine the state of each comparator line and dispatch interrupts */
  
    pr = getreg32(STM32L4_EXTI1_PR);
    for (i = 0; i < STM32L4_COMP_NUM; i++)
      {
        ln = g_comp_lines[i];
        if ((pr & ln) != 0)
          {
            /* Clear the pending interrupt */
  
            putreg32(ln, STM32L4_EXTI1_PR);
            if (g_comp_handlers[i].callback != NULL)
              {
                xcpt_t callback = g_comp_handlers[i].callback;
                void *callback_arg = g_comp_handlers[i].arg;
                ret = callback(irq, context, callback_arg);
              }
          }
      }
  
    return ret;
  }
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: stm32l4_exti_comp
   *
   * Description:
   *   Sets/clears comparator based events and interrupt triggers.
   *
   * Input Parameters:
   *  - cmp: comparator
   *  - rising/falling edge: enables interrupt on rising/falling edget
   *  - event:  generate event when set
   *  - func:   when non-NULL, generate interrupt
   *  - arg:    Argument passed to the interrupt callback
   *
   * Returned Value:
   *   Zero (OK) returned on success; a negated errno value is returned on
   *   failure.
   *
   ****************************************************************************/
  
  int stm32l4_exti_comp(int cmp, bool risingedge, bool fallingedge,
                        bool event, xcpt_t func, void *arg)
  {
    irqstate_t flags;
    uint32_t ln = g_comp_lines[cmp];
  
   /* Perform the following within a critical section so that the handler gets
    * installed correctly before the next interrupt is received.
    */
  
    flags = enter_critical_section();
  
    /* Install external interrupt handlers */
  
    if (func != NULL)
      {
        irq_attach(STM32L4_IRQ_COMP, stm32l4_exti_comp_isr, NULL);
        up_enable_irq(STM32L4_IRQ_COMP);
      }
    else
      {
        up_disable_irq(STM32L4_IRQ_COMP);
      }
  
    /* Configure rising/falling edges */
  
    modifyreg32(STM32L4_EXTI1_RTSR, risingedge  ? 0 : ln, risingedge  ? ln : 0);
    modifyreg32(STM32L4_EXTI1_FTSR, fallingedge ? 0 : ln, fallingedge ? ln : 0);
  
    /* Enable Events and Interrupts */
  
    modifyreg32(STM32L4_EXTI1_EMR, event ? 0 : ln, event ? ln : 0);
    modifyreg32(STM32L4_EXTI1_IMR, func  ? 0 : ln, func  ? ln : 0);
  
    /* Get the previous IRQ handler and save the new IRQ handler. */
  
    g_comp_handlers[cmp].callback = func;
    g_comp_handlers[cmp].arg      = arg;
  
    /* Leave the critical section */
  
    leave_critical_section(flags);
    return OK;
  }
  