tinySA/os/hal/platforms/LPC8xx/gpt_lld.c

/*
    ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
                 2011,2012,2013 Giovanni Di Sirio.

    This file is part of ChibiOS/RT.

    ChibiOS/RT 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.

    ChibiOS/RT 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/>.
*/

/**
 * @file    LPC8xx/gpt_lld.c
 * @brief   LPC8xx GPT subsystem low level driver source.
 *
 * @addtogroup GPT
 * @{
 */

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

#if HAL_USE_GPT || defined(__DOXYGEN__)

/*===========================================================================*/
/* Driver exported variables.                                                */
/*===========================================================================*/

/**
 * @brief   GPT1 driver identifier.
 * @note    The driver GPT1 allocates MRT channel0 when enabled.
 */
#if LPC8xx_GPT_USE_MRT0 || defined(__DOXYGEN__)
GPTDriver GPTD1;
#endif

/**
 * @brief   GPT2 driver identifier.
 * @note    The driver GPT1 allocates MRT channel1 when enabled.
 */
#if LPC8xx_GPT_USE_MRT1 || defined(__DOXYGEN__)
GPTDriver GPTD2;
#endif

/**
 * @brief   GPT3 driver identifier.
 * @note    The driver GPT1 allocates MRT channel2 when enabled.
 */
#if LPC8xx_GPT_USE_MRT2 || defined(__DOXYGEN__)
GPTDriver GPTD3;
#endif

/**
 * @brief   GPT4 driver identifier.
 * @note    The driver GPT1 allocates MRT channel3 when enabled.
 */
#if LPC8xx_GPT_USE_MRT3 || defined(__DOXYGEN__)
GPTDriver GPTD4;
#endif

/*===========================================================================*/
/* Driver local variables.                                                   */
/*===========================================================================*/
static uint32_t clk_enabled;

/*===========================================================================*/
/* Driver local functions.                                                   */
/*===========================================================================*/
/**
 * @brief   Shared IRQ handler.
 *
 * @param[in] gptp      pointer to a @p GPTDriver object
 * @param[in] irq_flag  irq flag bit
 */

static void gpt_lld_serve_interrupt( GPTDriver *gptp ) {

  if (gptp->tmr->STAT & 0x01) {
    gptp->tmr->STAT |= 0x01;

    if (gptp->state == GPT_ONESHOT) {
      gptp->state = GPT_READY;                /* Back in GPT_READY state.     */
    }
    gptp->config->callback(gptp);
  }
  return;
}

/*===========================================================================*/
/* Driver interrupt handlers.                                                */
/*===========================================================================*/

/**

 * @brief   MRT IRQ handler.
 *
 */
CH_IRQ_HANDLER(Vector68) {
  CH_IRQ_PROLOGUE();
  
#if LPC8xx_GPT_USE_MRT0
  gpt_lld_serve_interrupt( &GPTD1 );
#endif
  
#if LPC8xx_GPT_USE_MRT1
  gpt_lld_serve_interrupt( &GPTD2 );
#endif

#if LPC8xx_GPT_USE_MRT2
  gpt_lld_serve_interrupt( &GPTD3 );
#endif

#if LPC8xx_GPT_USE_MRT3
  gpt_lld_serve_interrupt( &GPTD4 );
#endif

  CH_IRQ_EPILOGUE();
}

/*===========================================================================*/
/* Driver exported functions.                                                */
/*===========================================================================*/

/**
 * @brief   Low level GPT driver initialization.
 *
 * @notapi
 */
void gpt_lld_init(void) {

#if LPC8xx_GPT_USE_MRT0
  GPTD1.tmr = &(LPC_MRT->Channel[0]);
  gptObjectInit(&GPTD1);
  GPTD1.mask = (1<<0);
#endif

#if LPC8xx_GPT_USE_MRT1
  GPTD2.tmr = &(LPC_MRT->Channel[1]);
  gptObjectInit(&GPTD2);
  GPTD1.mask = (1<<1);
#endif

#if LPC8xx_GPT_USE_MRT2
  GPTD3.tmr = &(LPC_MRT->Channel[2]);
  gptObjectInit(&GPTD3);
  GPTD1.mask = (1<<2);
#endif

#if LPC8xx_GPT_USE_MRT3
  GPTD4.tmr = &(LPC_MRT->Channel[3]);
  gptObjectInit(&GPTD4);
  GPTD1.mask = (1<<3);
#endif

  clk_enabled = FALSE;
  return;
}

/**
 * @brief   Configures and activates a GPT channel.
 *
 * @param[in] gptp      pointer to the @p GPTDriver object
 *
 * @notapi
 */
void gpt_lld_start(GPTDriver *gptp) {

  if( !clk_enabled ) {
  
    /* Enable clock & reset MRT */
    LPC_SYSCON->SYSAHBCLKCTRL |=  (1<<10);
    LPC_SYSCON->PRESETCTRL    &= ~(1<<7);
    LPC_SYSCON->PRESETCTRL    |=  (1<<7);

    nvicEnableVector(MRT_IRQn,
                     CORTEX_PRIORITY_MASK(LPC8xx_GPT_MRT_IRQ_PRIORITY));
                     
    clk_enabled |= gptp->mask;
  }

  /* Prescaler value calculation.*/
  gptp->pr = (LPC8xx_SYSCLK / gptp->config->frequency);
  chDbgAssert((gptp->pr * gptp->config->frequency) == LPC8xx_SYSCLK,
              "gpt_lld_start(), #1", "invalid frequency");

  /* MRT Channel configuration.*/
  gptp->tmr->CTRL  = 0;
  gptp->tmr->STAT |= 1;

}

/**
 * @brief   Deactivates a GPT channel.
 *
 * @param[in] gptp      pointer to the @p GPTDriver object
 *
 * @notapi
 */
void gpt_lld_stop(GPTDriver *gptp) {

  /* Shared peripheral - 
     mark this channel as disabled */
  clk_enabled &= ~gptp->mask;
  
  /* All channels disabled? */
  if( !clk_enabled )
  {
    /* Disable periheral */
    nvicDisableVector(MRT_IRQn);
    LPC_SYSCON->SYSAHBCLKCTRL &=  ~(1<<10);
  }
    
  return;
}

/**
 * @brief   Starts the timer in continuous/One shot mode.
 *
 * @param[in] gptp      pointer to the @p GPTDriver object
 * @param[in] interval  period in ticks
 *
 * @notapi
 */
void gpt_lld_start_timer(GPTDriver *gptp, gptcnt_t interval) {

  gptp->tmr->INTVAL = (1<<31)|((interval*gptp->pr) - 1);

  if (gptp->state == GPT_ONESHOT)
    gptp->tmr->CTRL = (1<<1)|1;
  else
    gptp->tmr->CTRL = 1;
}

/**
 * @brief   Stops the timer.
 *
 * @param[in] gptp      pointer to the @p GPTDriver object
 *
 * @notapi
 */
void gpt_lld_stop_timer(GPTDriver *gptp) {

  gptp->tmr->INTVAL = (1<<31);
  gptp->tmr->CTRL   = 0;
  gptp->tmr->STAT  |= 1;
}

/**
 * @brief   Starts the timer in one shot mode and waits for completion.
 * @details This function specifically polls the timer waiting for completion
 *          in order to not have extra delays caused by interrupt servicing,
 *          this function is only recommended for short delays.
 *
 * @param[in] gptp      pointer to the @p GPTDriver object
 * @param[in] interval  time interval in ticks
 *
 * @notapi
 */
void gpt_lld_polled_delay(GPTDriver *gptp, gptcnt_t interval) {

  gptp->tmr->INTVAL = (1<<31)|((interval*gptp->pr) - 1);
  gptp->tmr->CTRL = (1<<1);

  while (gptp->tmr->STAT & (1<<1))
    ;
    
  gptp->tmr->CTRL   = 0;
  gptp->tmr->STAT  |= 1;
}

#endif /* HAL_USE_GPT */

/** @} */