source: rtems/c/src/lib/libbsp/arm/shared/arm-a9mpcore-clock-config.c @ 8fbe2e6

/*
 * Copyright (c) 2013-2014 embedded brains GmbH.  All rights reserved.
 *
 *  embedded brains GmbH
 *  Dornierstr. 4
 *  82178 Puchheim
 *  Germany
 *  <info@embedded-brains.de>
 *
 * 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 <bsp.h>
#include <bsp/fatal.h>
#include <bsp/irq.h>
#include <bsp/arm-a9mpcore-regs.h>
#include <bsp/arm-a9mpcore-clock.h>

#define A9MPCORE_GT ((volatile a9mpcore_gt *) BSP_ARM_A9MPCORE_GT_BASE)

static uint64_t a9mpcore_clock_last_tick_k;

static uint32_t a9mpcore_clock_last_tick_cmpvallower;

static uint32_t a9mpcore_clock_autoinc;

/* This is defined in clockdrv_shell.h */
void Clock_isr(rtems_irq_hdl_param arg);

__attribute__ ((weak)) uint32_t a9mpcore_clock_periphclk(void)
{
  /* default to the BSP option. */
  return BSP_ARM_A9MPCORE_PERIPHCLK;
}

static void a9mpcore_clock_at_tick(void)
{
  volatile a9mpcore_gt *gt = A9MPCORE_GT;

  /*
   * FIXME: Now the _TOD_Get_with_nanoseconds() yields wrong values until
   * _TOD_Tickle_ticks() managed to update the uptime.  See also PR2180.
   */
  a9mpcore_clock_last_tick_cmpvallower =
    gt->cmpvallower - a9mpcore_clock_autoinc;

  gt->irqst = A9MPCORE_GT_IRQST_EFLG;
}

static void a9mpcore_clock_handler_install(void)
{
  rtems_status_code sc;

  sc = rtems_interrupt_handler_install(
    A9MPCORE_IRQ_GT,
    "Clock",
    RTEMS_INTERRUPT_UNIQUE,
    (rtems_interrupt_handler) Clock_isr,
    NULL
  );
  if (sc != RTEMS_SUCCESSFUL) {
    bsp_fatal(BSP_ARM_A9MPCORE_FATAL_CLOCK_IRQ_INSTALL);
  }
}

static uint64_t a9mpcore_clock_get_counter(volatile a9mpcore_gt *gt)
{
  uint32_t cl;
  uint32_t cu1;
  uint32_t cu2;

  do {
    cu1 = gt->cntrupper;
    cl = gt->cntrlower;
    cu2 = gt->cntrupper;
  } while (cu1 != cu2);

  return ((uint64_t) cu2 << 32) | cl;
}

static void a9mpcore_clock_initialize(void)
{
  volatile a9mpcore_gt *gt = A9MPCORE_GT;
  uint64_t periphclk = a9mpcore_clock_periphclk();
  uint64_t us_per_tick = rtems_configuration_get_microseconds_per_tick();
  uint32_t interval = (uint32_t) ((periphclk * us_per_tick) / 1000000);
  uint64_t cmpval;

  gt->ctrl &= A9MPCORE_GT_CTRL_TMR_EN;
  gt->irqst = A9MPCORE_GT_IRQST_EFLG;

  cmpval = a9mpcore_clock_get_counter(gt);
  cmpval += interval;

  gt->cmpvallower = (uint32_t) cmpval;
  gt->cmpvalupper = (uint32_t) (cmpval >> 32);
  gt->autoinc = interval;

  a9mpcore_clock_last_tick_k = (UINT64_C(1000000000) << 32) / periphclk;
  a9mpcore_clock_last_tick_cmpvallower = (uint32_t) cmpval - interval;
  a9mpcore_clock_autoinc = interval;

  gt->ctrl = A9MPCORE_GT_CTRL_AUTOINC_EN
    | A9MPCORE_GT_CTRL_IRQ_EN
    | A9MPCORE_GT_CTRL_COMP_EN
    | A9MPCORE_GT_CTRL_TMR_EN;
}

CPU_Counter_ticks _CPU_Counter_read(void)
{
  volatile a9mpcore_gt *gt = A9MPCORE_GT;

  return gt->cntrlower;
}

static void a9mpcore_clock_cleanup_isr(void *arg)
{
  volatile a9mpcore_gt *gt = A9MPCORE_GT;

  (void) arg;

  gt->ctrl &= A9MPCORE_GT_CTRL_TMR_EN;
  gt->irqst = A9MPCORE_GT_IRQST_EFLG;
}

static void a9mpcore_clock_cleanup(void)
{
  rtems_status_code sc;

  /*
   * The relevant registers / bits of the global timer are banked and chances
   * are on an SPM system, that we are executing on the wrong CPU to reset
   * them. Thus we will have the actual cleanup done with the next clock tick.
   * The ISR will execute on the right CPU for the cleanup.
   */
  sc = rtems_interrupt_handler_install(
    A9MPCORE_IRQ_GT,
    "Clock",
    RTEMS_INTERRUPT_REPLACE,
    a9mpcore_clock_cleanup_isr,
    NULL
  );
  if (sc != RTEMS_SUCCESSFUL) {
    bsp_fatal(BSP_ARM_A9MPCORE_FATAL_CLOCK_IRQ_REMOVE);
  }
}

static uint32_t a9mpcore_clock_nanoseconds_since_last_tick(void)
{
  volatile a9mpcore_gt *gt = A9MPCORE_GT;
  uint64_t k = a9mpcore_clock_last_tick_k;
  uint32_t n = a9mpcore_clock_last_tick_cmpvallower;
  uint32_t c = gt->cntrlower;

  return (uint32_t) (((c - n) * k) >> 32);
}

#define Clock_driver_support_at_tick() \
  a9mpcore_clock_at_tick()

#define Clock_driver_support_initialize_hardware() \
  a9mpcore_clock_initialize()

#define Clock_driver_support_install_isr(isr, old_isr) \
  do { \
    a9mpcore_clock_handler_install();   \
    old_isr = NULL; \
  } while (0)

#define Clock_driver_support_shutdown_hardware() \
  a9mpcore_clock_cleanup()

#define Clock_driver_nanoseconds_since_last_tick \
  a9mpcore_clock_nanoseconds_since_last_tick

/* Include shared source clock driver code */
#include "../../shared/clockdrv_shell.h"