mvme147/btimer/btimer.c

0001 /* SPDX-License-Identifier: BSD-2-Clause */
0002
0003 /*
0004  *  COPYRIGHT (c) 1989-1999.
0005  *  On-Line Applications Research Corporation (OAR).
0006  *
0007  * Redistribution and use in source and binary forms, with or without
0008  * modification, are permitted provided that the following conditions
0009  * are met:
0010  * 1. Redistributions of source code must retain the above copyright
0011  *    notice, this list of conditions and the following disclaimer.
0012  * 2. Redistributions in binary form must reproduce the above copyright
0013  *    notice, this list of conditions and the following disclaimer in the
0014  *    documentation and/or other materials provided with the distribution.
0015  *
0016  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
0017  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
0018  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
0019  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
0020  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
0021  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
0022  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
0023  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
0024  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
0025  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
0026  * POSSIBILITY OF SUCH DAMAGE.
0027  *
0028  *  MVME147 port for TNI - Telecom Bretagne
0029  *  by Dominique LE CAMPION (Dominique.LECAMPION@enst-bretagne.fr)
0030  *  May 1996
0031  */
0032
0033 #include <rtems/btimer.h>
0034 #include <bsp.h>
0035
0036 #define TIMER_INT_LEVEL 6
0037
0038 #define COUNTDOWN_VALUE 0
0039 /* Allows 0.4096 second delay betwin ints */
0040 /* Each tick is 6.25 us */
0041
0042 int Ttimer_val;
0043 bool benchmark_timer_find_average_overhead;
0044
0045 rtems_isr timerisr(rtems_vector_number);
0046
0047 void benchmark_timer_initialize(void)
0048 {
0049   (void) set_vector(timerisr, TIMER_1_VECTOR, 0); /* install ISR */
0050
0051   Ttimer_val = 0;                 /* clear timer ISR count */
0052   pcc->timer1_int_control = 0x00; /* Disable T1 Interr. */
0053   pcc->timer1_preload = COUNTDOWN_VALUE;
0054   /* write countdown preload value */
0055   pcc->timer1_control = 0x00; /* load preload value */
0056   pcc->timer1_control = 0x07; /* clear T1 overflow counter, enable counter */
0057   pcc->timer1_int_control = TIMER_INT_LEVEL|0x08;
0058   /* Enable Timer 1 and set its int. level */
0059
0060 }
0061
0062 #define AVG_OVERHEAD      0  /* No need to start/stop the timer to read
0063                 its value on the MVME147 PCC: reads are not
0064                 synchronized whith the counter updates*/
0065 #define LEAST_VALID       10 /* Don't trust a value lower than this */
0066
0067 benchmark_timer_t benchmark_timer_read(void)
0068 {
0069   uint32_t         total;
0070   uint16_t         counter_value;
0071
0072   counter_value = pcc->timer1_count; /* read the counter value */
0073
0074   total = ((Ttimer_val * 0x10000) + counter_value); /* in 6.25 us units */
0075   /* DC note : just look at the assembly generated
0076      to see gcc's impressive optimization ! */
0077   return total;
0078
0079 }
0080
0081 void benchmark_timer_disable_subtracting_average_overhead(
0082   bool find_flag
0083 )
0084 {
0085   benchmark_timer_find_average_overhead = find_flag;
0086 }