File: [local] / prex / sys / arch / arm / gba / clock.c (download)
Revision 1.1.1.1 (vendor branch), Tue Aug 19 12:46:56 2008 UTC (16 years ago) by nbrk
Branch: MAIN, KOHSUKE
CVS Tags: PREX_0_8_BASE, HEAD Changes since 1.1: +0 -0 lines
Initial import of Prex, Portable Real-time Embedded POSIX microkernel system.
I have totally new directions in my development (more focused on real hardware, not virtual one).
Old hacks are available in prex-old module. They will be carefully re-designed and merged soon.
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/*-
* Copyright (c) 2005-2007, Kohsuke Ohtani
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* clock.c - clock driver
*/
#include <kernel.h>
#include <timer.h>
#include <irq.h>
/* Interrupt vector for timer (TMR0 of GBA) */
#define CLOCK_IRQ 3
/* The clock rate per second ... 2^24 */
#define CLOCK_RATE 16777216L
/* The initial counter value */
#define TIMER_COUNT (0xffff - (CLOCK_RATE / 64 / HZ))
/* GBA timer registers */
#define TMR0_COUNT (*(volatile uint16_t *)0x4000100)
#define TMR0_CTRL (*(volatile uint16_t *)0x4000102)
/* Timer frequency */
#define TMR_1_CLOCK 0x0000
#define TMR_64_CLOCK 0x0001
#define TMR_256_CLOCK 0x0002
#define TMR_1024_CLOCK 0x0003
/* Cascade switch */
#define TMR_CASCADE 0x0004
/* Interrupt for overflow */
#define TMR_IRQEN 0x0040
/* Timer switch */
#define TMR_EN 0x0080
/*
* Clock interrupt service routine.
* No H/W reprogram is required.
*/
static int
clock_isr(int irq)
{
irq_lock();
timer_tick();
irq_unlock();
return INT_DONE;
}
/*
* Initialize clock H/W chip.
* Setup clock tick rate and install clock ISR.
*/
void
clock_init(void)
{
irq_t clock_irq;
TMR0_COUNT = TIMER_COUNT;
TMR0_CTRL = (uint16_t)(TMR_IRQEN | TMR_64_CLOCK);
clock_irq = irq_attach(CLOCK_IRQ, IPL_CLOCK, 0, &clock_isr, NULL);
TMR0_CTRL |= TMR_EN;
ASSERT(clock_irq != NULL);
}