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/**
* @file
*
* @ingroup RTEMSDriverClockImpl
*
* @brief This source file contains the implementation of the BCM2835 Clock
* Driver.
*/
/*
* Copyright (c) 2013 Alan Cudmore
* Copyright (c) 2016 Pavel Pisa
*
* 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 <bsp/irq-generic.h>
#include <bsp/raspberrypi.h>
#include <rtems/timecounter.h>
static struct timecounter raspberrypi_tc;
static uint32_t raspberrypi_clock_get_timecount(struct timecounter *tc)
{
return BCM2835_REG(BCM2835_GPU_TIMER_CLO);
}
static void raspberrypi_clock_at_tick(void)
{
uint32_t act_val;
uint32_t next_cmp = BCM2835_REG(BCM2835_GPU_TIMER_C3);
next_cmp += rtems_configuration_get_microseconds_per_tick();
BCM2835_REG(BCM2835_GPU_TIMER_C3) = next_cmp;
act_val = BCM2835_REG(BCM2835_GPU_TIMER_CLO);
/*
* Clear interrupt only if there is time left to the next tick.
* If time of the next tick has already passed then interrupt
* request stays active and fires immediately after current tick
* processing is finished.
*/
if ((int32_t)(next_cmp - act_val) > 0)
BCM2835_REG(BCM2835_GPU_TIMER_CS) = BCM2835_GPU_TIMER_CS_M3;
}
static void raspberrypi_clock_handler_install_isr(
rtems_interrupt_handler clock_isr
)
{
rtems_status_code sc = RTEMS_SUCCESSFUL;
sc = rtems_interrupt_handler_install(
BCM2835_IRQ_ID_GPU_TIMER_M3,
"Clock",
RTEMS_INTERRUPT_UNIQUE,
clock_isr,
NULL
);
if ( sc != RTEMS_SUCCESSFUL ) {
rtems_fatal_error_occurred(0xdeadbeef);
}
}
static void raspberrypi_clock_initialize_hardware(void)
{
uint32_t next_cmp = BCM2835_REG(BCM2835_GPU_TIMER_CLO);
next_cmp += rtems_configuration_get_microseconds_per_tick();
BCM2835_REG(BCM2835_GPU_TIMER_C3) = next_cmp;
BCM2835_REG(BCM2835_GPU_TIMER_CS) = BCM2835_GPU_TIMER_CS_M3;
raspberrypi_tc.tc_get_timecount = raspberrypi_clock_get_timecount;
raspberrypi_tc.tc_counter_mask = 0xffffffff;
raspberrypi_tc.tc_frequency = 1000000; /* 1 MHz */
raspberrypi_tc.tc_quality = RTEMS_TIMECOUNTER_QUALITY_CLOCK_DRIVER;
rtems_timecounter_install(&raspberrypi_tc);
}
#define Clock_driver_support_at_tick(arg) raspberrypi_clock_at_tick()
#define Clock_driver_support_initialize_hardware() raspberrypi_clock_initialize_hardware()
#define Clock_driver_support_install_isr(clock_isr) \
raspberrypi_clock_handler_install_isr(clock_isr)
#define CLOCK_DRIVER_USE_ONLY_BOOT_PROCESSOR 1
#include "../../../shared/dev/clock/clockimpl.h"
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