gen68340/clock/ckinit.c

0001 /* SPDX-License-Identifier: BSD-2-Clause */
0002
0003 /*
0004  * This routine initializes the MC68340/349 Periodic Interval Timer
0005  */
0006
0007 /*
0008  * Based on the `gen68360' board support package, and covered by the
0009  * original distribution terms.
0010  *
0011  * Geoffroy Montel
0012  * France Telecom - CNET/DSM/TAM/CAT
0013  * 4, rue du Clos Courtel
0014  * 35512 CESSON-SEVIGNE
0015  * FRANCE
0016  *
0017  * e-mail: g_montel@yahoo.com
0018  */
0019
0020 /*
0021  * COPYRIGHT (c) 1989-2014.
0022  * On-Line Applications Research Corporation (OAR).
0023  *
0024  * Redistribution and use in source and binary forms, with or without
0025  * modification, are permitted provided that the following conditions
0026  * are met:
0027  * 1. Redistributions of source code must retain the above copyright
0028  *    notice, this list of conditions and the following disclaimer.
0029  * 2. Redistributions in binary form must reproduce the above copyright
0030  *    notice, this list of conditions and the following disclaimer in the
0031  *    documentation and/or other materials provided with the distribution.
0032  *
0033  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
0034  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
0035  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
0036  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
0037  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
0038  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
0039  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
0040  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
0041  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
0042  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
0043  * POSSIBILITY OF SUCH DAMAGE.
0044  */
0045
0046 #include <stdlib.h>       /* for atexit() */
0047 #include <bsp.h>
0048 #include <m68340.h>
0049 #include <rtems/clockdrv.h>
0050
0051 #define CLOCK_VECTOR     120 /* clock isr routine vector in the vbr */
0052 #define CLOCK_IRQ_LEVEL  6   /* clock isr level */
0053
0054 /*
0055  * Clock_driver_ticks is a monotonically increasing counter of the
0056  * number of clock ticks since the driver was initialized.
0057  */
0058 volatile uint32_t         Clock_driver_ticks;
0059
0060 /*
0061  * Periodic interval timer interrupt handler
0062  */
0063 static rtems_isr
0064 Clock_isr (rtems_vector_number vector)
0065 {
0066   /*
0067    * Announce the clock tick
0068    */
0069   Clock_driver_ticks++;
0070   rtems_clock_tick();
0071 }
0072
0073 static void
0074 Clock_exit (void)
0075 {
0076   /*
0077    * Turn off periodic interval timer
0078    */
0079   SIMPITR = 0;
0080 }
0081
0082 static void
0083 Install_clock (rtems_isr_entry clock_isr)
0084 {
0085   uint32_t   pitr_tmp;
0086   uint32_t   usecs_per_tick;
0087
0088   Clock_driver_ticks = 0;
0089
0090   set_vector (clock_isr, CLOCK_VECTOR, 1);
0091
0092   /* sets the Periodic Interrupt Control Register PICR */
0093   SIMPICR = ( CLOCK_IRQ_LEVEL << 8 ) | ( CLOCK_VECTOR );
0094
0095   /* sets the PITR count value */
0096   /* this assumes a 32.765 kHz crystal */
0097
0098   usecs_per_tick = rtems_configuration_get_microseconds_per_tick();
0099   /* find out whether prescaler should be enabled or not */
0100   if ( usecs_per_tick <= 31128 ) {
0101      pitr_tmp = ( usecs_per_tick * 8192 ) / 1000000 ;
0102   } else {
0103      pitr_tmp = ( usecs_per_tick / 1000000 ) * 16;
0104      /* enable it */
0105      pitr_tmp |= 0x100;
0106   }
0107
0108   SIMPITR = (unsigned char) pitr_tmp;
0109
0110   atexit (Clock_exit);
0111 }
0112
0113 void _Clock_Initialize( void )
0114 {
0115   Install_clock (Clock_isr);
0116 }