forked from Imagelibrary/rtems
b2a4e861dc
* Makefile.am: Add s3c2400/lcd/lcd.c, s3c2400/clock/support.c * s3c2400/clock/clockdrv.c: Update to use get_PCLK() * s3c2400/timer/timer.c: Update to use get_PCLK()
121 lines
2.8 KiB
C
121 lines
2.8 KiB
C
/*
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* S3C2400 Timer driver
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*
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* This uses timer 1 for timing measurments.
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*
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* The license and distribution terms for this file may be
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* found in the file LICENSE in this distribution or at
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*
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* http://www.OARcorp.com/rtems/license.html.
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*
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* Notes:
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* This file manages the benchmark timer used by the RTEMS Timing Test
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* Suite. Each measured time period is demarcated by calls to
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* Timer_initialize() and Read_timer(). Read_timer() usually returns
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* the number of microseconds since Timer_initialize() exitted.
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*
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* It is important that the timer start/stop overhead be determined
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* when porting or modifying this code.
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*
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* $Id$
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*/
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#include <rtems.h>
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#include <bsp.h>
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#include <s3c2400.h>
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uint32_t g_start;
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uint32_t g_freq;
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rtems_boolean Timer_driver_Find_average_overhead;
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/*
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* Set up Timer 1
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*/
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void Timer_initialize( void )
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{
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uint32_t cr;
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/* stop TIMER1*/
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cr=rTCON & 0xFFFFF0FF;
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rTCON=(cr | (0x0 << 8));
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/* set MUX for Timer1 to 1/2 */
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cr=rTCFG1 & 0xFFFFFF0F;
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rTCFG1=(cr | (0<<4));
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/* input freq=PLCK/2 Mhz*/
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g_freq = get_PCLK() / 2000;
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rTCNTB1 = 0xFFFF;
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/* start TIMER1 with manual reload */
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cr=rTCON & 0xFFFFF0FF;
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rTCON=(cr | (0x1 << 9));
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rTCON=(cr | (0x1 << 8));
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g_start = rTCNTO1;
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}
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/*
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* The following controls the behavior of Read_timer().
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*
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* AVG_OVEREHAD is the overhead for starting and stopping the timer. It
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* is usually deducted from the number returned.
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*
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* LEAST_VALID is the lowest number this routine should trust. Numbers
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* below this are "noise" and zero is returned.
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*/
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#define AVG_OVERHEAD 0 /* It typically takes X.X microseconds */
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/* (Y countdowns) to start/stop the timer. */
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/* This value is in microseconds. */
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#define LEAST_VALID 1 /* Don't trust a clicks value lower than this */
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int Read_timer( void )
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{
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uint32_t t;
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unsigned long long total;
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t = rTCNTO1;
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/*
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* Total is calculated by taking into account the number of timer overflow
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* interrupts since the timer was initialized and clicks since the last
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* interrupts.
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*/
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total = (g_start - t);
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/* convert to microseconds */
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total = (total*1000) / g_freq;
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if ( Timer_driver_Find_average_overhead == 1 ) {
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return (int) total;
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} else if ( total < LEAST_VALID ) {
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return 0;
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}
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/*
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* Somehow convert total into microseconds
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*/
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return (total - AVG_OVERHEAD);
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}
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/*
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* Empty function call used in loops to measure basic cost of looping
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* in Timing Test Suite.
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*/
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rtems_status_code Empty_function( void )
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{
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return RTEMS_SUCCESSFUL;
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}
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void Set_find_average_overhead(
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rtems_boolean find_flag
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)
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{
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Timer_driver_Find_average_overhead = find_flag;
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}
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