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Diffstat (limited to 'c/src/lib/libbsp/m68k/mvme167/timer/timer.c')
-rw-r--r-- | c/src/lib/libbsp/m68k/mvme167/timer/timer.c | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/c/src/lib/libbsp/m68k/mvme167/timer/timer.c b/c/src/lib/libbsp/m68k/mvme167/timer/timer.c new file mode 100644 index 0000000000..37cb269ae1 --- /dev/null +++ b/c/src/lib/libbsp/m68k/mvme167/timer/timer.c @@ -0,0 +1,153 @@ +/* timer.c + * + * This file manages the benchmark timer used by the RTEMS Timing Test Suite. + * Each measured time period is demarcated by calls to Timer_initialize() and + * Read_timer(). Read_timer() usually returns the number of microseconds + * since Timer_initialize() exitted. + * + * These functions are prototyped in rtems/c/src/lib/include/timerdrv.h and + * must be implemented as part of the BSP. + * + * This port does not allow the application to select which timer on the + * MVME167 to use for the timer, nor does it allow the application to + * configure the timer. The timer uses the VMEchip2 Tick Timer #1. This timer + * is distinct from the clock, which uses Tick Timer #2 in the VMEchip2. + * + * All page references are to the MVME166/MVME167/MVME187 Single Board + * Computer Programmer's Reference Guide (MVME187PG/D2) with the April 1993 + * supplements/addenda (MVME187PG/D2A1). + * + * COPYRIGHT (c) 1989-1998. + * On-Line Applications Research Corporation (OAR). + * Copyright assigned to U.S. Government, 1994. + * + * The license and distribution terms for this file may be + * found in the file LICENSE in this distribution or at + * http://www.OARcorp.com/rtems/license.html. + * + * Modifications of respective RTEMS file: + * Copyright (c) 1998, National Research Council of Canada + * + * $Id$ + */ + +#include <rtems.h> +#include <bsp.h> + +/* Periodic tick interval */ +#define TICK_INTERVAL 10000UL /* T1's countdown constant (10 ms) */ +#define TIMER_INT_LEVEL 6 /* T1's interrupt level */ +#define TIMER_VECTOR (VBR0 * 0x10 + 0x8) /* T1 is vector $X8 (p. 2-71)*/ + +/* Number of interrupts since timer was re-initialized */ +rtems_unsigned32 Ttimer_val; + +/* + * Set to TRUE to return raw value. Normally zero. Depends on being allocated + * in the .bss section and on that section being explicitly zeroed at boot + * time. + */ +rtems_boolean Timer_driver_Find_average_overhead; + +rtems_isr timerisr(); + +/* + * This routine initializes the Tick Timer 1 on the MVME167 board. + * + * Input parameters: NONE + * + * Output parameters: NONE + * + * NOTE: This routine may not work if the optimizer is enabled for some + * compilers. The multiple writes may be optimized away. + * + * It is important that the timer start/stop overhead be + * determined when porting or modifying this code. + * + * THE VMECHIP2 PRESCALER REGISTER IS ASSUMED TO BE SET! + * The prescaler is used by all VMEchip2 timers, including the VMEbus grant + * timeout counter, the DMAC time off timer, the DMAC timer on timer, and the + * VMEbus global timeout timer. The prescaler value is normally set by the + * boot ROM to provide a 1 MHz clock to the timers. For a 25 MHz MVME167, the + * prescaler value should be 0xE7 (page 2-63). + */ +void Timer_initialize() +{ + (void) set_vector( timerisr, TIMER_VECTOR, 0 ); + + Ttimer_val = 0; /* clear timer ISR count */ + lcsr->intr_ena &= 0xFEFFFFFF; /* disable tick timer 1 interrupt */ + lcsr->intr_clear |= 0x01000000; /* clear tick timer 1 interrupt */ + lcsr->intr_level[0] = /* set int level */ + (lcsr->intr_level[0] & 0xFFFFFFF0) | TIMER_INT_LEVEL; + lcsr->timer_cmp_1 = TICK_INTERVAL; /* period in compare register */ + lcsr->timer_cnt_1 = 0; /* clear tick timer 1 counter */ + lcsr->board_ctl |= 7; /* start tick timer 1, reset-on-compare, */ + /* and clear overflow counter */ + + lcsr->intr_ena |= 0x01000000; /* enable tick timer 1 interrupt */ + lcsr->vector_base |= MASK_INT; /* unmask VMEchip2 interrupts */ +} + +#define AVG_OVERHEAD 3UL /* It typically takes 3.0 microseconds */ + /* (3 countdowns) to start/stop the timer. */ +#define LEAST_VALID 3UL /* Don't trust a value lower than this */ + + +/* + * This routine reads the Tick Timer 1 on the MVME167 board. + * + * Input parameters: NONE + * + * Output parameters: time in microseconds + * + * AVG_OVEREHAD is the overhead for starting and stopping the timer. It + * is usually deducted from the number returned. + * + * LEAST_VALID is the lowest number this routine should trust. Numbers + * below this are "noise" and zero is returned. + */ +int Read_timer() +{ + rtems_unsigned32 total; + + total = (Ttimer_val * TICK_INTERVAL) + lcsr->timer_cnt_1; + + if ( Timer_driver_Find_average_overhead ) + return total; /* in one microsecond units */ + + if ( total < LEAST_VALID ) + return 0; /* below timer resolution */ + + return total - AVG_OVERHEAD; +} + + +/* + * Empty function call used in loops to measure basic cost of looping + * in Timing Test Suite. + * + * Input parameters: NONE + * + * Output parameters: time in microseconds + */ +rtems_status_code Empty_function( void ) +{ + return RTEMS_SUCCESSFUL; +} + + +/* + * This routine sets the Timer_driver_Find_average_overhead flag in this + * module. + * + * Input parameters: NONE + * + * Output parameters: time in microseconds + */ +void Set_find_average_overhead( + rtems_boolean find_flag +) +{ + Timer_driver_Find_average_overhead = find_flag; +} |