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