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Diffstat (limited to 'c/src/lib/libbsp/arm/csb336/timer/timer.c')
-rw-r--r-- | c/src/lib/libbsp/arm/csb336/timer/timer.c | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/c/src/lib/libbsp/arm/csb336/timer/timer.c b/c/src/lib/libbsp/arm/csb336/timer/timer.c new file mode 100644 index 0000000000..66ff4a0bf4 --- /dev/null +++ b/c/src/lib/libbsp/arm/csb336/timer/timer.c @@ -0,0 +1,93 @@ +/** + * @file + * @brief Cogent CSB336 Timer driver + * + * This uses timer 2 for timing measurments. + */ + +/* + * Copyright (c) 2004 Cogent Computer Systems + * Written by Jay Monkman <jtm@lopingdog.com> + * + * 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 <rtems/btimer.h> +#include <mc9328mxl.h> + +uint32_t g_start; +uint32_t g_freq; + +bool benchmark_timer_find_average_overhead; + + +/* + * Set up Timer 1 + */ +void benchmark_timer_initialize( void ) +{ + MC9328MXL_TMR2_TCTL = (MC9328MXL_TMR_TCTL_CLKSRC_PCLK1 | + MC9328MXL_TMR_TCTL_FRR | + MC9328MXL_TMR_TCTL_TEN); + /* set prescaler to 1 (register value + 1) */ \ + MC9328MXL_TMR2_TPRER = 0; + + /* get freq of counter in KHz */ + g_freq = get_perclk1_freq() / 1000; + + g_start = MC9328MXL_TMR2_TCN; +} + +/* + * The following controls the behavior of benchmark_timer_read(). + * + * 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. + */ + +#define AVG_OVERHEAD 0 /* It typically takes X.X microseconds */ + /* (Y countdowns) to start/stop the timer. */ + /* This value is in microseconds. */ +#define LEAST_VALID 1 /* Don't trust a clicks value lower than this */ + +benchmark_timer_t benchmark_timer_read( void ) +{ + uint32_t t; + unsigned long long total; + + t = MC9328MXL_TMR2_TCN; + /* + * Total is calculated by taking into account the number of timer overflow + * interrupts since the timer was initialized and clicks since the last + * interrupts. + */ + + total = (t - g_start); + + /* convert to nanoseconds */ + total = (total * 1000)/ g_freq; + + if ( benchmark_timer_find_average_overhead == 1 ) { + return (int) total; + } else if ( total < LEAST_VALID ) { + return 0; + } + /* + * Somehow convert total into microseconds + */ + + return (total - AVG_OVERHEAD); +} + +void benchmark_timer_disable_subtracting_average_overhead(bool find_flag) +{ + benchmark_timer_find_average_overhead = find_flag; +} + |