diff options
Diffstat (limited to 'c/src/lib/libbsp/arm/smdk2410/timer/timer.c')
-rw-r--r-- | c/src/lib/libbsp/arm/smdk2410/timer/timer.c | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/c/src/lib/libbsp/arm/smdk2410/timer/timer.c b/c/src/lib/libbsp/arm/smdk2410/timer/timer.c new file mode 100644 index 0000000000..2bc599df75 --- /dev/null +++ b/c/src/lib/libbsp/arm/smdk2410/timer/timer.c @@ -0,0 +1,100 @@ +/** + * @file + * @brief S3C2400 Timer driver + * + * This uses timer 1 for timing measurments. + */ + +/* + * 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 <bsp.h> +#include <rtems.h> +#include <rtems/btimer.h> +#include <s3c24xx.h> + +uint32_t g_start; +uint32_t g_freq; + +bool benchmark_timer_find_average_overhead; + + +/* + * Set up Timer 1 + */ +void benchmark_timer_initialize( void ) +{ + uint32_t cr; + + /* stop TIMER1*/ + cr=rTCON & 0xFFFFF0FF; + rTCON=(cr | (0x0 << 8)); + + /* set MUX for Timer1 to 1/2 */ + cr=rTCFG1 & 0xFFFFFF0F; + rTCFG1=(cr | (0<<4)); + + /* input freq=PLCK/2 Mhz*/ + g_freq = get_PCLK() / 2000; + rTCNTB1 = 0xFFFF; + + /* start TIMER1 with manual reload */ + cr=rTCON & 0xFFFFF0FF; + rTCON=(cr | (0x1 << 9)); + rTCON=(cr | (0x1 << 8)); + + g_start = rTCNTO1; +} + +/* + * 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 = rTCNTO1; + /* + * 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 = (g_start - t); + + /* convert to microseconds */ + 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; +} + |