path: root/c/src/lib/libbsp/m68k/uC5282/clock/clock.c

/*
 * Use the last periodic interval timer (PIT3) as the system clock.
 *
 *  Author: W. Eric Norum <norume@aps.anl.gov>
 *
 *  COPYRIGHT (c) 2005.
 *  On-Line Applications Research Corporation (OAR).
 *
 *  The license and distribution terms for this file may be
 *  found in the file LICENSE in this distribution or at
 *  http://www.rtems.com/license/LICENSE.
 *
 *  $Id$
 */

#include <rtems.h>
#include <bsp.h>
#include <mcf5282/mcf5282.h>

/*
 * Use INTC0 base
 */
#define CLOCK_VECTOR (64+58)

/*
 * CPU load counters
 * Place in static RAM so updates don't hit the SDRAM
 */
extern int __SRAMBASE[];
#define IDLE_COUNTER      __SRAMBASE[0]
#define FILTERED_IDLE     __SRAMBASE[1]
#define MAX_IDLE_COUNT    __SRAMBASE[2]
#define PCNTR_AT_TICK     (*(uint16 *)&__SRAMBASE[3])
#define FILTER_SHIFT    6

uint32_t bsp_clock_nanoseconds_since_last_tick(void)
{
    int i = MCF5282_PIT3_PCNTR;
    if (MCF5282_PIT3_PCSR & MCF5282_PIT_PCSR_PIF)
        i = MCF5282_PIT3_PCNTR + MCF5282_PIT3_PMR;
    return (i - PCNTR_AT_TICK) * 1000;
}

#define Clock_driver_nanoseconds_since_last_tick bsp_clock_nanoseconds_since_last_tick

/*
 * Periodic interval timer interrupt handler
 */
#define Clock_driver_support_at_tick()                                       \
    do {                                                                     \
        int idle = IDLE_COUNTER;                                             \
        IDLE_COUNTER = 0;                                                    \
        if (idle > MAX_IDLE_COUNT)                                           \
            MAX_IDLE_COUNT = idle;                                           \
        FILTERED_IDLE = idle + FILTERED_IDLE - (FILTERED_IDLE>>FILTER_SHIFT);\
        PCNTR_AT_TICK = MCF5282_PIT3_PCNTR;                                  \
        MCF5282_PIT3_PCSR |= MCF5282_PIT_PCSR_PIF;                           \
    } while (0)

/*
 * Attach clock interrupt handler
 */
#define Clock_driver_support_install_isr( _new, _old )              \
    do {                                                            \
        _old = (rtems_isr_entry)set_vector(_new, CLOCK_VECTOR, 1);  \
    } while(0)

/*
 * Turn off the clock
 */
#define Clock_driver_support_shutdown_hardware()   \
    do {                                           \
        MCF5282_PIT3_PCSR &= ~MCF5282_PIT_PCSR_EN; \
    } while(0)

/*
 * Set up the clock hardware
 *
 * Prescale so that it counts in microseconds
 * System clock frequency better be 2**n (1<=n<=16) MHz!
 */
#define Clock_driver_support_initialize_hardware()                       \
    do {                                                                 \
        int level;                                                       \
        int preScaleCode = -2;                                           \
        int preScaleDivisor = bsp_get_CPU_clock_speed() / 1000000;       \
        while (preScaleDivisor) {                                        \
            preScaleDivisor >>= 1;                                       \
            preScaleCode++;                                              \
        }                                                                \
        IDLE_COUNTER = 0;                                                \
        FILTERED_IDLE = 0;                                               \
        MAX_IDLE_COUNT = 0;                                              \
        bsp_allocate_interrupt(PIT3_IRQ_LEVEL, PIT3_IRQ_PRIORITY);       \
        MCF5282_INTC0_ICR58 = MCF5282_INTC_ICR_IL(PIT3_IRQ_LEVEL) |      \
                              MCF5282_INTC_ICR_IP(PIT3_IRQ_PRIORITY);    \
        rtems_interrupt_disable( level );                                \
        MCF5282_INTC0_IMRH &= ~MCF5282_INTC_IMRH_INT58;                  \
        MCF5282_PIT3_PCSR &= ~MCF5282_PIT_PCSR_EN;                       \
        rtems_interrupt_enable( level );                                 \
        MCF5282_PIT3_PCSR = MCF5282_PIT_PCSR_PRE(preScaleCode) |         \
                            MCF5282_PIT_PCSR_OVW |                       \
                            MCF5282_PIT_PCSR_PIE |                       \
                            MCF5282_PIT_PCSR_RLD;                        \
        MCF5282_PIT3_PMR = BSP_Configuration.microseconds_per_tick - 1;  \
        MCF5282_PIT3_PCSR = MCF5282_PIT_PCSR_PRE(preScaleCode) |         \
                            MCF5282_PIT_PCSR_PIE |                       \
                            MCF5282_PIT_PCSR_RLD |                       \
                            MCF5282_PIT_PCSR_EN;                         \
        PCNTR_AT_TICK = MCF5282_PIT3_PCNTR;                              \
    } while (0)

/*
 * Provide our own version of the idle task
 */
void _BSP_Thread_Idle_body(void)
{
    for(;;)
        asm volatile ("addq.l #1,__SRAMBASE"); /* Atomic increment */
}

int rtems_bsp_cpu_load_percentage(void)
{
    return MAX_IDLE_COUNT ?
           (100 - ((100 * (FILTERED_IDLE >> FILTER_SHIFT)) / MAX_IDLE_COUNT)) :
           0;
}

#include "../../../shared/clockdrv_shell.c"