source: rtems/c/src/lib/libcpu/arm/lpc22xx/clock/clockdrv.c @ 175c85b

/*
 *  LPC22XX/LPC21xx clock specific using the System Timer
 *
 *  Set the Time0 to generate click for RTEMS
 */

/*
 *  Copyright (c) 2006 by Ray <rayx.cn@gmail.com>
 *
 *  The license and distribution terms for this file may be
 *  found in the file LICENSE in this distribution or at
 *  http://www.rtems.org/license/LICENSE.
 */

#include <rtems.h>
#include <bsp.h>
#include <bsp/irq.h>
#include <lpc22xx.h>
#include <rtems/bspIo.h>  /* for printk */

void Clock_isr(rtems_irq_hdl_param arg);
static void clock_isr_on(const rtems_irq_connect_data *unused);
static void clock_isr_off(const rtems_irq_connect_data *unused);
static int clock_isr_is_on(const rtems_irq_connect_data *irq);

/* Replace the first value with the clock's interrupt name. */
rtems_irq_connect_data clock_isr_data = {
  .name   = LPC22xx_INTERRUPT_TIMER0,
  .hdl    = Clock_isr,
  .handle = NULL,
  .on     = clock_isr_on,
  .off    = clock_isr_off,
  .isOn   = clock_isr_is_on,
};

/* use the /shared/clockdrv_shell.h code template */

/**
 * When we get the clock interrupt
 *    - clear the interrupt bit?
 *    - restart the timer?
 */
#define Clock_driver_support_at_tick() \
 do {                                  \
   if (!(T0IR & 0x01))                 \
     return;                           \
   T0IR = 0x01;                        \
   VICVectAddr = 0x00;                 \
 } while(0)

/**
 * Installs the clock ISR. You shouldn't need to change this.
 */
#define Clock_driver_support_install_isr( _new, _old ) \
  do {                                                 \
    (_old) = NULL;                                   \
    BSP_install_rtems_irq_handler(&clock_isr_data);  \
  } while(0)

/**
 * Initialize the hardware for the clock
 *   - Set the frequency
 *   - enable it
 *   - clear any pending interrupts
 *
 * Since you may want the clock always running, you can
 * enable interrupts here. If you do so, the clock_isr_on(),
 * clock_isr_off(), and clock_isr_is_on() functions can be
 * NOPs.
 * 
 * set timer to generate interrupt every
 * rtems_configuration_get_microseconds_per_tick()
 *     MR0/(LPC22xx_Fpclk/(PR0+1)) = 10/1000 = 0.01s
 */
#define Clock_driver_support_initialize_hardware() \
  do { \
    /* disable and clear timer 0, set to  */ \
    T0TCR &= 0;                              \
    /* TC is incrementet on every pclk.*/    \
    T0PC   = 0;                              \
    /* initialize the timer period and prescaler */  \
    T0MR0  = ((LPC22xx_Fpclk/1000 *          \
             rtems_configuration_get_microseconds_per_tick()) / 1000); \
    /* generate interrupt when T0MR0 match T0TC and Reset Timer Count*/ \
    T0MCR |= 0x03;          \
    /* No external match */ \
    T0EMR = 0;              \
    /* enable timer0 */     \
    T0TCR = 1;              \
    /* enable interrupt, skyeye will check this*/ \
    T0IR |= 0x01; \
  } while (0)

/**
 * Do whatever you need to shut the clock down and remove the
 * interrupt handler. Since this normally only gets called on
 * RTEMS shutdown, you may not need to do anything other than
 * remove the ISR.
 */
#define Clock_driver_support_shutdown_hardware()                        \
  do {                                                                  \
    /* Disable timer */ \
    T0TCR&=~0x02; \
    BSP_remove_rtems_irq_handler(&clock_isr_data);                  \
  } while (0)

static uint32_t bsp_clock_nanoseconds_since_last_tick(void)
{
  uint32_t clicks;
  uint32_t microseconds;

  clicks = T0TC;  /* T0TC is the 32bit time counter 0 */

  microseconds = (rtems_configuration_get_microseconds_per_tick() - clicks);
  return microseconds * 1000;
}

#define Clock_driver_nanoseconds_since_last_tick \
        bsp_clock_nanoseconds_since_last_tick

/**
 * Enables clock interrupt.
 *
 * If the interrupt is always on, this can be a NOP.
 */
static void clock_isr_on(const rtems_irq_connect_data *unused)
{
  T0IR&=0x01;
}

/**
 * Disables clock interrupts
 *
 * If the interrupt is always on, this can be a NOP.
 */
static void clock_isr_off(const rtems_irq_connect_data *unused)
{
  T0IR=0x00;
}

/**
 * Tests to see if clock interrupt is enabled, and returns 1 if so.
 * If interrupt is not enabled, returns 0.
 *
 * If the interrupt is always on, this always returns 1.
 */
static int clock_isr_is_on(const rtems_irq_connect_data *irq)
{
  return T0IR & 0x01;  /* MR0 mask */
}

/* Make sure to include this, and only at the end of the file */
#include "../../../../libbsp/shared/clockdrv_shell.h"