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Annotation of prex-old/sys/arch/arm/gba/clock.c, Revision 1.1.1.1

1.1       nbrk        1: /*-
                      2:  * Copyright (c) 2005-2007, Kohsuke Ohtani
                      3:  * All rights reserved.
                      4:  *
                      5:  * Redistribution and use in source and binary forms, with or without
                      6:  * modification, are permitted provided that the following conditions
                      7:  * are met:
                      8:  * 1. Redistributions of source code must retain the above copyright
                      9:  *    notice, this list of conditions and the following disclaimer.
                     10:  * 2. Redistributions in binary form must reproduce the above copyright
                     11:  *    notice, this list of conditions and the following disclaimer in the
                     12:  *    documentation and/or other materials provided with the distribution.
                     13:  * 3. Neither the name of the author nor the names of any co-contributors
                     14:  *    may be used to endorse or promote products derived from this software
                     15:  *    without specific prior written permission.
                     16:  *
                     17:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
                     18:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     19:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     20:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
                     21:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     22:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     23:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     24:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     25:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     26:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     27:  * SUCH DAMAGE.
                     28:  */
                     29:
                     30: /*
                     31:  * clock.c - clock driver
                     32:  */
                     33:
                     34: #include <kernel.h>
                     35: #include <timer.h>
                     36: #include <irq.h>
                     37:
                     38: /* Interrupt vector for timer (TMR0 of GBA) */
                     39: #define CLOCK_IRQ      3
                     40:
                     41: /* The clock rate per second ... 2^24 */
                     42: #define CLOCK_RATE     16777216L
                     43:
                     44: /* The initial counter value */
                     45: #define TIMER_COUNT    (0xffff - (CLOCK_RATE / 64 / HZ))
                     46:
                     47: /* GBA timer registers */
                     48: #define TMR0_COUNT     (*(volatile uint16_t *)0x4000100)
                     49: #define TMR0_CTRL      (*(volatile uint16_t *)0x4000102)
                     50:
                     51: /* Timer frequency */
                     52: #define TMR_1_CLOCK    0x0000
                     53: #define TMR_64_CLOCK   0x0001
                     54: #define TMR_256_CLOCK  0x0002
                     55: #define TMR_1024_CLOCK 0x0003
                     56:
                     57: /* Cascade switch */
                     58: #define TMR_CASCADE    0x0004
                     59:
                     60: /* Interrupt for overflow */
                     61: #define        TMR_IRQEN       0x0040
                     62:
                     63: /* Timer switch */
                     64: #define TMR_EN         0x0080
                     65:
                     66: /*
                     67:  * Clock interrupt service routine.
                     68:  * No H/W reprogram is required.
                     69:  */
                     70: static int
                     71: clock_isr(int irq)
                     72: {
                     73:
                     74:        irq_lock();
                     75:        timer_tick();
                     76:        irq_unlock();
                     77:
                     78:        return INT_DONE;
                     79: }
                     80:
                     81: /*
                     82:  * Initialize clock H/W chip.
                     83:  * Setup clock tick rate and install clock ISR.
                     84:  */
                     85: void
                     86: clock_init(void)
                     87: {
                     88:        int clock_irq;
                     89:
                     90:        TMR0_COUNT = TIMER_COUNT;
                     91:        TMR0_CTRL = (uint16_t)(TMR_IRQEN | TMR_64_CLOCK);
                     92:        clock_irq = irq_attach(CLOCK_IRQ, IPL_CLOCK, 0, clock_isr, NULL);
                     93:        TMR0_CTRL |= TMR_EN;
                     94:
                     95:        ASSERT(clock_irq != -1);
                     96: }